From 00140a8308367208d56e93cf08fa1636202a0dc7 Mon Sep 17 00:00:00 2001 From: Boqun Feng Date: Tue, 7 Feb 2023 10:52:15 -0800 Subject: rust: sync: impl {Debug,Display} for {Unique,}Arc MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit This allows printing the inner data of `Arc` and its friends if the inner data implements `Display` or `Debug`. It's useful for logging and debugging purpose. Signed-off-by: Boqun Feng Reviewed-by: Vincenzo Palazzo Reviewed-by: Gary Guo Reviewed-by: Andreas Hindborg Reviewed-by: Björn Roy Baron Link: https://lore.kernel.org/r/20230207185216.1314638-2-boqun.feng@gmail.com Signed-off-by: Miguel Ojeda --- rust/kernel/sync/arc.rs | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) (limited to 'rust') diff --git a/rust/kernel/sync/arc.rs b/rust/kernel/sync/arc.rs index f2f1c83d72ba..a94e303217c6 100644 --- a/rust/kernel/sync/arc.rs +++ b/rust/kernel/sync/arc.rs @@ -22,6 +22,7 @@ use crate::{ }; use alloc::boxed::Box; use core::{ + fmt, marker::{PhantomData, Unsize}, mem::{ManuallyDrop, MaybeUninit}, ops::{Deref, DerefMut}, @@ -522,3 +523,27 @@ impl DerefMut for UniqueArc { unsafe { &mut self.inner.ptr.as_mut().data } } } + +impl fmt::Display for UniqueArc { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + fmt::Display::fmt(self.deref(), f) + } +} + +impl fmt::Display for Arc { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + fmt::Display::fmt(self.deref(), f) + } +} + +impl fmt::Debug for UniqueArc { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + fmt::Debug::fmt(self.deref(), f) + } +} + +impl fmt::Debug for Arc { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + fmt::Debug::fmt(self.deref(), f) + } +} -- cgit v1.2.3 From 3c01a424a37fe625052c68c8620f6aa701f77769 Mon Sep 17 00:00:00 2001 From: Asahi Lina Date: Fri, 24 Feb 2023 17:09:47 +0900 Subject: rust: Enable the new_uninit feature for kernel and driver crates The unstable new_uninit feature enables various library APIs to create uninitialized containers, such as `Box::assume_init()`. This is necessary to build abstractions that directly initialize memory at the target location, instead of doing copies through the stack. Will be used by the DRM scheduler abstraction in the kernel crate, and by field-wise initialization (e.g. using `place!()` or a future replacement macro which may itself live in `kernel`) in driver crates. Link: https://github.com/Rust-for-Linux/linux/issues/879 Link: https://github.com/Rust-for-Linux/linux/issues/2 Link: https://github.com/rust-lang/rust/issues/63291 Signed-off-by: Asahi Lina Reviewed-by: Martin Rodriguez Reboredo Reviewed-by: Gary Guo Reviewed-by: Andreas Hindborg Reviewed-by: Vincenzo Palazzo Link: https://lore.kernel.org/r/20230224-rust-new_uninit-v1-1-c951443d9e26@asahilina.net [ Reworded to use `Link` tags. ] Signed-off-by: Miguel Ojeda --- rust/kernel/lib.rs | 1 + 1 file changed, 1 insertion(+) (limited to 'rust') diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs index 223564f9f0cc..1118cd3e0b5f 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -17,6 +17,7 @@ #![feature(core_ffi_c)] #![feature(dispatch_from_dyn)] #![feature(generic_associated_types)] +#![feature(new_uninit)] #![feature(receiver_trait)] #![feature(unsize)] -- cgit v1.2.3 From 65b571afdfdcefa09508274488086b218e34906d Mon Sep 17 00:00:00 2001 From: Asahi Lina Date: Fri, 24 Feb 2023 18:11:47 +0900 Subject: rust: Import upstream `alloc::vec::set_len_on_drop` module This is a subset of the Rust standard library `alloc` crate, version 1.62.0, licensed under "Apache-2.0 OR MIT", from: https://github.com/rust-lang/rust/tree/1.62.0/library/alloc/src The file is copied as-is, with no modifications whatsoever (not even adding the SPDX identifiers). For copyright details, please see: https://github.com/rust-lang/rust/blob/1.62.0/COPYRIGHT Signed-off-by: Asahi Lina Link: https://lore.kernel.org/r/20230224-rust-vec-v1-1-733b5b5a57c5@asahilina.net [ Import version 1.62.0 instead, to match the one in mainline. ] Signed-off-by: Miguel Ojeda --- rust/alloc/vec/set_len_on_drop.rs | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+) create mode 100644 rust/alloc/vec/set_len_on_drop.rs (limited to 'rust') diff --git a/rust/alloc/vec/set_len_on_drop.rs b/rust/alloc/vec/set_len_on_drop.rs new file mode 100644 index 000000000000..8b66bc812129 --- /dev/null +++ b/rust/alloc/vec/set_len_on_drop.rs @@ -0,0 +1,28 @@ +// Set the length of the vec when the `SetLenOnDrop` value goes out of scope. +// +// The idea is: The length field in SetLenOnDrop is a local variable +// that the optimizer will see does not alias with any stores through the Vec's data +// pointer. This is a workaround for alias analysis issue #32155 +pub(super) struct SetLenOnDrop<'a> { + len: &'a mut usize, + local_len: usize, +} + +impl<'a> SetLenOnDrop<'a> { + #[inline] + pub(super) fn new(len: &'a mut usize) -> Self { + SetLenOnDrop { local_len: *len, len } + } + + #[inline] + pub(super) fn increment_len(&mut self, increment: usize) { + self.local_len += increment; + } +} + +impl Drop for SetLenOnDrop<'_> { + #[inline] + fn drop(&mut self) { + *self.len = self.local_len; + } +} -- cgit v1.2.3 From ae12ae137270e2e8890dd375aeca6d90556d2629 Mon Sep 17 00:00:00 2001 From: Asahi Lina Date: Fri, 24 Feb 2023 18:11:48 +0900 Subject: rust: Import upstream `alloc::vec::spec_extend` module This is a subset of the Rust standard library `alloc` crate, version 1.62.0, licensed under "Apache-2.0 OR MIT", from: https://github.com/rust-lang/rust/tree/1.62.0/library/alloc/src The file is copied as-is, with no modifications whatsoever (not even adding the SPDX identifiers). For copyright details, please see: https://github.com/rust-lang/rust/blob/1.62.0/COPYRIGHT Signed-off-by: Asahi Lina Link: https://lore.kernel.org/r/20230224-rust-vec-v1-2-733b5b5a57c5@asahilina.net [ Import version 1.62.0 instead, to match the one in mainline. ] Signed-off-by: Miguel Ojeda --- rust/alloc/vec/spec_extend.rs | 87 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 87 insertions(+) create mode 100644 rust/alloc/vec/spec_extend.rs (limited to 'rust') diff --git a/rust/alloc/vec/spec_extend.rs b/rust/alloc/vec/spec_extend.rs new file mode 100644 index 000000000000..506ee0ecfa27 --- /dev/null +++ b/rust/alloc/vec/spec_extend.rs @@ -0,0 +1,87 @@ +use crate::alloc::Allocator; +use core::iter::TrustedLen; +use core::ptr::{self}; +use core::slice::{self}; + +use super::{IntoIter, SetLenOnDrop, Vec}; + +// Specialization trait used for Vec::extend +pub(super) trait SpecExtend { + fn spec_extend(&mut self, iter: I); +} + +impl SpecExtend for Vec +where + I: Iterator, +{ + default fn spec_extend(&mut self, iter: I) { + self.extend_desugared(iter) + } +} + +impl SpecExtend for Vec +where + I: TrustedLen, +{ + default fn spec_extend(&mut self, iterator: I) { + // This is the case for a TrustedLen iterator. + let (low, high) = iterator.size_hint(); + if let Some(additional) = high { + debug_assert_eq!( + low, + additional, + "TrustedLen iterator's size hint is not exact: {:?}", + (low, high) + ); + self.reserve(additional); + unsafe { + let mut ptr = self.as_mut_ptr().add(self.len()); + let mut local_len = SetLenOnDrop::new(&mut self.len); + iterator.for_each(move |element| { + ptr::write(ptr, element); + ptr = ptr.offset(1); + // Since the loop executes user code which can panic we have to bump the pointer + // after each step. + // NB can't overflow since we would have had to alloc the address space + local_len.increment_len(1); + }); + } + } else { + // Per TrustedLen contract a `None` upper bound means that the iterator length + // truly exceeds usize::MAX, which would eventually lead to a capacity overflow anyway. + // Since the other branch already panics eagerly (via `reserve()`) we do the same here. + // This avoids additional codegen for a fallback code path which would eventually + // panic anyway. + panic!("capacity overflow"); + } + } +} + +impl SpecExtend> for Vec { + fn spec_extend(&mut self, mut iterator: IntoIter) { + unsafe { + self.append_elements(iterator.as_slice() as _); + } + iterator.forget_remaining_elements(); + } +} + +impl<'a, T: 'a, I, A: Allocator + 'a> SpecExtend<&'a T, I> for Vec +where + I: Iterator, + T: Clone, +{ + default fn spec_extend(&mut self, iterator: I) { + self.spec_extend(iterator.cloned()) + } +} + +impl<'a, T: 'a, A: Allocator + 'a> SpecExtend<&'a T, slice::Iter<'a, T>> for Vec +where + T: Copy, +{ + fn spec_extend(&mut self, iterator: slice::Iter<'a, T>) { + let slice = iterator.as_slice(); + unsafe { self.append_elements(slice) }; + } +} -- cgit v1.2.3 From 3dcb652a3afc4b32cf8d3c1605c8cf22ad174a07 Mon Sep 17 00:00:00 2001 From: Asahi Lina Date: Fri, 24 Feb 2023 18:11:49 +0900 Subject: rust: Add SPDX headers to alloc::vec::{spec_extend, set_len_on_drop} Add the missing SPDX headers to these modules, which were just imported from the Rust stdlib. Doing this in a separate commit makes it easier to audit that the files have not been modified in the original import. See the preceding two commits for attribution and licensing details. Signed-off-by: Asahi Lina Link: https://lore.kernel.org/r/20230224-rust-vec-v1-3-733b5b5a57c5@asahilina.net [ Reworded for typo. ] Signed-off-by: Miguel Ojeda --- rust/alloc/vec/set_len_on_drop.rs | 2 ++ rust/alloc/vec/spec_extend.rs | 2 ++ 2 files changed, 4 insertions(+) (limited to 'rust') diff --git a/rust/alloc/vec/set_len_on_drop.rs b/rust/alloc/vec/set_len_on_drop.rs index 8b66bc812129..448bf5076a0b 100644 --- a/rust/alloc/vec/set_len_on_drop.rs +++ b/rust/alloc/vec/set_len_on_drop.rs @@ -1,3 +1,5 @@ +// SPDX-License-Identifier: Apache-2.0 OR MIT + // Set the length of the vec when the `SetLenOnDrop` value goes out of scope. // // The idea is: The length field in SetLenOnDrop is a local variable diff --git a/rust/alloc/vec/spec_extend.rs b/rust/alloc/vec/spec_extend.rs index 506ee0ecfa27..7bb3abb7ee71 100644 --- a/rust/alloc/vec/spec_extend.rs +++ b/rust/alloc/vec/spec_extend.rs @@ -1,3 +1,5 @@ +// SPDX-License-Identifier: Apache-2.0 OR MIT + use crate::alloc::Allocator; use core::iter::TrustedLen; use core::ptr::{self}; -- cgit v1.2.3 From 318c3cc8e107c2b36108132057ca90d0d56d1bd9 Mon Sep 17 00:00:00 2001 From: Miguel Ojeda Date: Fri, 24 Feb 2023 18:11:50 +0900 Subject: rust: alloc: vec: Add some try_* methods we need Add some missing fallible methods that we need. They are all marked as: #[stable(feature = "kernel", since = "1.0.0")] for easy identification. Lina: Extracted from commit 487d7578bd03 ("rust: alloc: add some `try_*` methods we need") in rust-for-linux/rust. Signed-off-by: Miguel Ojeda Signed-off-by: Asahi Lina Link: https://github.com/Rust-for-Linux/linux/commit/487d7578bd03 Link: https://lore.kernel.org/r/20230224-rust-vec-v1-4-733b5b5a57c5@asahilina.net [ Match the non-fallible methods from version 1.62.0, since those in commit 487d7578bd03 were written for 1.54.0-beta.1. ] Signed-off-by: Miguel Ojeda --- rust/alloc/vec/mod.rs | 137 +++++++++++++++++++++++++++++++++++++++++- rust/alloc/vec/spec_extend.rs | 85 ++++++++++++++++++++++++++ 2 files changed, 219 insertions(+), 3 deletions(-) (limited to 'rust') diff --git a/rust/alloc/vec/mod.rs b/rust/alloc/vec/mod.rs index f77c7368d534..fe4fff5064bc 100644 --- a/rust/alloc/vec/mod.rs +++ b/rust/alloc/vec/mod.rs @@ -122,10 +122,8 @@ use self::spec_from_elem::SpecFromElem; #[cfg(not(no_global_oom_handling))] mod spec_from_elem; -#[cfg(not(no_global_oom_handling))] use self::set_len_on_drop::SetLenOnDrop; -#[cfg(not(no_global_oom_handling))] mod set_len_on_drop; #[cfg(not(no_global_oom_handling))] @@ -149,7 +147,8 @@ mod spec_from_iter; #[cfg(not(no_global_oom_handling))] use self::spec_extend::SpecExtend; -#[cfg(not(no_global_oom_handling))] +use self::spec_extend::TrySpecExtend; + mod spec_extend; /// A contiguous growable array type, written as `Vec`, short for 'vector'. @@ -1919,6 +1918,17 @@ impl Vec { self.len += count; } + /// Tries to append elements to `self` from other buffer. + #[inline] + unsafe fn try_append_elements(&mut self, other: *const [T]) -> Result<(), TryReserveError> { + let count = unsafe { (*other).len() }; + self.try_reserve(count)?; + let len = self.len(); + unsafe { ptr::copy_nonoverlapping(other as *const T, self.as_mut_ptr().add(len), count) }; + self.len += count; + Ok(()) + } + /// Removes the specified range from the vector in bulk, returning all /// removed elements as an iterator. If the iterator is dropped before /// being fully consumed, it drops the remaining removed elements. @@ -2340,6 +2350,45 @@ impl Vec { } } + /// Tries to resize the `Vec` in-place so that `len` is equal to `new_len`. + /// + /// If `new_len` is greater than `len`, the `Vec` is extended by the + /// difference, with each additional slot filled with `value`. + /// If `new_len` is less than `len`, the `Vec` is simply truncated. + /// + /// This method requires `T` to implement [`Clone`], + /// in order to be able to clone the passed value. + /// If you need more flexibility (or want to rely on [`Default`] instead of + /// [`Clone`]), use [`Vec::resize_with`]. + /// If you only need to resize to a smaller size, use [`Vec::truncate`]. + /// + /// # Examples + /// + /// ``` + /// let mut vec = vec!["hello"]; + /// vec.try_resize(3, "world").unwrap(); + /// assert_eq!(vec, ["hello", "world", "world"]); + /// + /// let mut vec = vec![1, 2, 3, 4]; + /// vec.try_resize(2, 0).unwrap(); + /// assert_eq!(vec, [1, 2]); + /// + /// let mut vec = vec![42]; + /// let result = vec.try_resize(usize::MAX, 0); + /// assert!(result.is_err()); + /// ``` + #[stable(feature = "kernel", since = "1.0.0")] + pub fn try_resize(&mut self, new_len: usize, value: T) -> Result<(), TryReserveError> { + let len = self.len(); + + if new_len > len { + self.try_extend_with(new_len - len, ExtendElement(value)) + } else { + self.truncate(new_len); + Ok(()) + } + } + /// Clones and appends all elements in a slice to the `Vec`. /// /// Iterates over the slice `other`, clones each element, and then appends @@ -2365,6 +2414,30 @@ impl Vec { self.spec_extend(other.iter()) } + /// Tries to clone and append all elements in a slice to the `Vec`. + /// + /// Iterates over the slice `other`, clones each element, and then appends + /// it to this `Vec`. The `other` slice is traversed in-order. + /// + /// Note that this function is same as [`extend`] except that it is + /// specialized to work with slices instead. If and when Rust gets + /// specialization this function will likely be deprecated (but still + /// available). + /// + /// # Examples + /// + /// ``` + /// let mut vec = vec![1]; + /// vec.try_extend_from_slice(&[2, 3, 4]).unwrap(); + /// assert_eq!(vec, [1, 2, 3, 4]); + /// ``` + /// + /// [`extend`]: Vec::extend + #[stable(feature = "kernel", since = "1.0.0")] + pub fn try_extend_from_slice(&mut self, other: &[T]) -> Result<(), TryReserveError> { + self.try_spec_extend(other.iter()) + } + /// Copies elements from `src` range to the end of the vector. /// /// # Panics @@ -2504,6 +2577,36 @@ impl Vec { // len set by scope guard } } + + /// Try to extend the vector by `n` values, using the given generator. + fn try_extend_with>(&mut self, n: usize, mut value: E) -> Result<(), TryReserveError> { + self.try_reserve(n)?; + + unsafe { + let mut ptr = self.as_mut_ptr().add(self.len()); + // Use SetLenOnDrop to work around bug where compiler + // might not realize the store through `ptr` through self.set_len() + // don't alias. + let mut local_len = SetLenOnDrop::new(&mut self.len); + + // Write all elements except the last one + for _ in 1..n { + ptr::write(ptr, value.next()); + ptr = ptr.offset(1); + // Increment the length in every step in case next() panics + local_len.increment_len(1); + } + + if n > 0 { + // We can write the last element directly without cloning needlessly + ptr::write(ptr, value.last()); + local_len.increment_len(1); + } + + // len set by scope guard + Ok(()) + } + } } impl Vec { @@ -2838,6 +2941,34 @@ impl Vec { } } + // leaf method to which various SpecFrom/SpecExtend implementations delegate when + // they have no further optimizations to apply + fn try_extend_desugared>(&mut self, mut iterator: I) -> Result<(), TryReserveError> { + // This is the case for a general iterator. + // + // This function should be the moral equivalent of: + // + // for item in iterator { + // self.push(item); + // } + while let Some(element) = iterator.next() { + let len = self.len(); + if len == self.capacity() { + let (lower, _) = iterator.size_hint(); + self.try_reserve(lower.saturating_add(1))?; + } + unsafe { + ptr::write(self.as_mut_ptr().add(len), element); + // Since next() executes user code which can panic we have to bump the length + // after each step. + // NB can't overflow since we would have had to alloc the address space + self.set_len(len + 1); + } + } + + Ok(()) + } + /// Creates a splicing iterator that replaces the specified range in the vector /// with the given `replace_with` iterator and yields the removed items. /// `replace_with` does not need to be the same length as `range`. diff --git a/rust/alloc/vec/spec_extend.rs b/rust/alloc/vec/spec_extend.rs index 7bb3abb7ee71..5ce2d00991bc 100644 --- a/rust/alloc/vec/spec_extend.rs +++ b/rust/alloc/vec/spec_extend.rs @@ -1,6 +1,7 @@ // SPDX-License-Identifier: Apache-2.0 OR MIT use crate::alloc::Allocator; +use crate::collections::{TryReserveError, TryReserveErrorKind}; use core::iter::TrustedLen; use core::ptr::{self}; use core::slice::{self}; @@ -8,10 +9,17 @@ use core::slice::{self}; use super::{IntoIter, SetLenOnDrop, Vec}; // Specialization trait used for Vec::extend +#[cfg(not(no_global_oom_handling))] pub(super) trait SpecExtend { fn spec_extend(&mut self, iter: I); } +// Specialization trait used for Vec::try_extend +pub(super) trait TrySpecExtend { + fn try_spec_extend(&mut self, iter: I) -> Result<(), TryReserveError>; +} + +#[cfg(not(no_global_oom_handling))] impl SpecExtend for Vec where I: Iterator, @@ -21,6 +29,16 @@ where } } +impl TrySpecExtend for Vec +where + I: Iterator, +{ + default fn try_spec_extend(&mut self, iter: I) -> Result<(), TryReserveError> { + self.try_extend_desugared(iter) + } +} + +#[cfg(not(no_global_oom_handling))] impl SpecExtend for Vec where I: TrustedLen, @@ -59,6 +77,41 @@ where } } +impl TrySpecExtend for Vec +where + I: TrustedLen, +{ + default fn try_spec_extend(&mut self, iterator: I) -> Result<(), TryReserveError> { + // This is the case for a TrustedLen iterator. + let (low, high) = iterator.size_hint(); + if let Some(additional) = high { + debug_assert_eq!( + low, + additional, + "TrustedLen iterator's size hint is not exact: {:?}", + (low, high) + ); + self.try_reserve(additional)?; + unsafe { + let mut ptr = self.as_mut_ptr().add(self.len()); + let mut local_len = SetLenOnDrop::new(&mut self.len); + iterator.for_each(move |element| { + ptr::write(ptr, element); + ptr = ptr.offset(1); + // Since the loop executes user code which can panic we have to bump the pointer + // after each step. + // NB can't overflow since we would have had to alloc the address space + local_len.increment_len(1); + }); + } + Ok(()) + } else { + Err(TryReserveErrorKind::CapacityOverflow.into()) + } + } +} + +#[cfg(not(no_global_oom_handling))] impl SpecExtend> for Vec { fn spec_extend(&mut self, mut iterator: IntoIter) { unsafe { @@ -68,6 +121,17 @@ impl SpecExtend> for Vec { } } +impl TrySpecExtend> for Vec { + fn try_spec_extend(&mut self, mut iterator: IntoIter) -> Result<(), TryReserveError> { + unsafe { + self.try_append_elements(iterator.as_slice() as _)?; + } + iterator.forget_remaining_elements(); + Ok(()) + } +} + +#[cfg(not(no_global_oom_handling))] impl<'a, T: 'a, I, A: Allocator + 'a> SpecExtend<&'a T, I> for Vec where I: Iterator, @@ -78,6 +142,17 @@ where } } +impl<'a, T: 'a, I, A: Allocator + 'a> TrySpecExtend<&'a T, I> for Vec +where + I: Iterator, + T: Clone, +{ + default fn try_spec_extend(&mut self, iterator: I) -> Result<(), TryReserveError> { + self.try_spec_extend(iterator.cloned()) + } +} + +#[cfg(not(no_global_oom_handling))] impl<'a, T: 'a, A: Allocator + 'a> SpecExtend<&'a T, slice::Iter<'a, T>> for Vec where T: Copy, @@ -87,3 +162,13 @@ where unsafe { self.append_elements(slice) }; } } + +impl<'a, T: 'a, A: Allocator + 'a> TrySpecExtend<&'a T, slice::Iter<'a, T>> for Vec +where + T: Copy, +{ + fn try_spec_extend(&mut self, iterator: slice::Iter<'a, T>) -> Result<(), TryReserveError> { + let slice = iterator.as_slice(); + unsafe { self.try_append_elements(slice) } + } +} -- cgit v1.2.3 From 39867fec2855cf37e5542dc6a972bce8ee191a9c Mon Sep 17 00:00:00 2001 From: Asahi Lina Date: Thu, 23 Mar 2023 21:35:10 +0900 Subject: rust: macros: Allow specifying multiple module aliases Modules can (and usually do) have multiple alias tags, in order to specify multiple possible device matches for autoloading. Allow this by changing the alias ModuleInfo field to an Option>. Note: For normal device IDs this is autogenerated by modpost (which is not properly integrated with Rust support yet), so it is useful to be able to manually add device match aliases for now, and should still be useful in the future for corner cases that modpost does not handle. This pulls in the expect_group() helper from the rfl/rust branch (with credit to authors). Co-developed-by: Miguel Ojeda Signed-off-by: Miguel Ojeda Co-developed-by: Finn Behrens Signed-off-by: Finn Behrens Co-developed-by: Sumera Priyadarsini Signed-off-by: Sumera Priyadarsini Reviewed-by: Vincenzo Palazzo Signed-off-by: Asahi Lina Link: https://lore.kernel.org/r/20230224-rust-macros-v2-1-7396e8b7018d@asahilina.net Signed-off-by: Miguel Ojeda --- rust/macros/helpers.rs | 10 +++++++++- rust/macros/module.rs | 30 +++++++++++++++++++++++++----- 2 files changed, 34 insertions(+), 6 deletions(-) (limited to 'rust') diff --git a/rust/macros/helpers.rs b/rust/macros/helpers.rs index cf7ad950dc1e..b2bdd4d8c958 100644 --- a/rust/macros/helpers.rs +++ b/rust/macros/helpers.rs @@ -1,6 +1,6 @@ // SPDX-License-Identifier: GPL-2.0 -use proc_macro::{token_stream, TokenTree}; +use proc_macro::{token_stream, Group, TokenTree}; pub(crate) fn try_ident(it: &mut token_stream::IntoIter) -> Option { if let Some(TokenTree::Ident(ident)) = it.next() { @@ -56,6 +56,14 @@ pub(crate) fn expect_string_ascii(it: &mut token_stream::IntoIter) -> String { string } +pub(crate) fn expect_group(it: &mut token_stream::IntoIter) -> Group { + if let TokenTree::Group(group) = it.next().expect("Reached end of token stream for Group") { + group + } else { + panic!("Expected Group"); + } +} + pub(crate) fn expect_end(it: &mut token_stream::IntoIter) { if it.next().is_some() { panic!("Expected end"); diff --git a/rust/macros/module.rs b/rust/macros/module.rs index a7e363c2b044..5e7ab83908a0 100644 --- a/rust/macros/module.rs +++ b/rust/macros/module.rs @@ -1,9 +1,27 @@ // SPDX-License-Identifier: GPL-2.0 use crate::helpers::*; -use proc_macro::{token_stream, Literal, TokenStream, TokenTree}; +use proc_macro::{token_stream, Delimiter, Literal, TokenStream, TokenTree}; use std::fmt::Write; +fn expect_string_array(it: &mut token_stream::IntoIter) -> Vec { + let group = expect_group(it); + assert_eq!(group.delimiter(), Delimiter::Bracket); + let mut values = Vec::new(); + let mut it = group.stream().into_iter(); + + while let Some(val) = try_string(&mut it) { + assert!(val.is_ascii(), "Expected ASCII string"); + values.push(val); + match it.next() { + Some(TokenTree::Punct(punct)) => assert_eq!(punct.as_char(), ','), + None => break, + _ => panic!("Expected ',' or end of array"), + } + } + values +} + struct ModInfoBuilder<'a> { module: &'a str, counter: usize, @@ -78,7 +96,7 @@ struct ModuleInfo { name: String, author: Option, description: Option, - alias: Option, + alias: Option>, } impl ModuleInfo { @@ -112,7 +130,7 @@ impl ModuleInfo { "author" => info.author = Some(expect_string(it)), "description" => info.description = Some(expect_string(it)), "license" => info.license = expect_string_ascii(it), - "alias" => info.alias = Some(expect_string_ascii(it)), + "alias" => info.alias = Some(expect_string_array(it)), _ => panic!( "Unknown key \"{}\". Valid keys are: {:?}.", key, EXPECTED_KEYS @@ -163,8 +181,10 @@ pub(crate) fn module(ts: TokenStream) -> TokenStream { modinfo.emit("description", &description); } modinfo.emit("license", &info.license); - if let Some(alias) = info.alias { - modinfo.emit("alias", &alias); + if let Some(aliases) = info.alias { + for alias in aliases { + modinfo.emit("alias", &alias); + } } // Built-in modules also export the `file` modinfo string. -- cgit v1.2.3 From 1edd03378e50ff1071004c80cb878e4bad73a68f Mon Sep 17 00:00:00 2001 From: Asahi Lina Date: Mon, 3 Apr 2023 19:01:11 +0900 Subject: rust: sync: arc: Implement Arc::downcast() This mirrors the standard library's alloc::sync::Arc::downcast(). Based on the Rust standard library implementation, ver 1.62.0, licensed under "Apache-2.0 OR MIT", from: https://github.com/rust-lang/rust/tree/1.62.0/library/alloc/src For copyright details, please see: https://github.com/rust-lang/rust/blob/1.62.0/COPYRIGHT Reviewed-by: Martin Rodriguez Reboredo Reviewed-by: Andreas Hindborg Reviewed-by: Vincenzo Palazzo Reviewed-by: Gary Guo Signed-off-by: Asahi Lina Link: https://lore.kernel.org/r/20230224-rust-arc-v2-1-5c97a865b276@asahilina.net [ Moved `mod std_vendor;` up. ] Signed-off-by: Miguel Ojeda --- rust/kernel/sync/arc.rs | 2 ++ rust/kernel/sync/arc/std_vendor.rs | 28 ++++++++++++++++++++++++++++ 2 files changed, 30 insertions(+) create mode 100644 rust/kernel/sync/arc/std_vendor.rs (limited to 'rust') diff --git a/rust/kernel/sync/arc.rs b/rust/kernel/sync/arc.rs index a94e303217c6..4ab9b280cb3d 100644 --- a/rust/kernel/sync/arc.rs +++ b/rust/kernel/sync/arc.rs @@ -30,6 +30,8 @@ use core::{ ptr::NonNull, }; +mod std_vendor; + /// A reference-counted pointer to an instance of `T`. /// /// The reference count is incremented when new instances of [`Arc`] are created, and decremented diff --git a/rust/kernel/sync/arc/std_vendor.rs b/rust/kernel/sync/arc/std_vendor.rs new file mode 100644 index 000000000000..a66a0c2831b3 --- /dev/null +++ b/rust/kernel/sync/arc/std_vendor.rs @@ -0,0 +1,28 @@ +// SPDX-License-Identifier: Apache-2.0 OR MIT + +//! The contents of this file come from the Rust standard library, hosted in +//! the repository, licensed under +//! "Apache-2.0 OR MIT" and adapted for kernel use. For copyright details, +//! see . + +use crate::sync::{arc::ArcInner, Arc}; +use core::any::Any; + +impl Arc { + /// Attempt to downcast the `Arc` to a concrete type. + pub fn downcast(self) -> core::result::Result, Self> + where + T: Any + Send + Sync, + { + if (*self).is::() { + // SAFETY: We have just checked that the type is correct, so we can cast the pointer. + unsafe { + let ptr = self.ptr.cast::>(); + core::mem::forget(self); + Ok(Arc::from_inner(ptr)) + } + } else { + Err(self) + } + } +} -- cgit v1.2.3 From 31d95c2f99bf16e59b996cf6a227e198a64e835c Mon Sep 17 00:00:00 2001 From: Asahi Lina Date: Mon, 3 Apr 2023 19:01:12 +0900 Subject: rust: sync: arc: Add UniqueArc::assume_init() We can already create `UniqueArc>` instances with `UniqueArc::try_new_uninit()` and write to them with `write()`. Add the missing unsafe `assume_init()` function to promote it to `UniqueArc`, so users can do piece-wise initialization of the contents instead of doing it all at once as long as they keep the invariants (the same requirements as `MaybeUninit::assume_init()`). This mirrors the std `Arc::assume_init()` function. In the kernel, since we have `UniqueArc`, arguably this only belongs there since most use cases will initialize it immediately after creating it, before demoting it to `Arc` to share it. [ Miguel: The "Rust pin-init API for pinned initialization of structs" patch series [1] from Benno Lossin contains a very similar patch: rust: sync: add `assume_init` to `UniqueArc` Adds the `assume_init` function to `UniqueArc>` that unsafely assumes the value to be initialized and yields a value of type `UniqueArc`. This function is used when manually initializing the pointee of an `UniqueArc`. To make that patch a noop and thus drop it, I adjusted the `SAFETY` comment here to be the same as in the current latest version of that series (v7). I have also brought the `Reviewed-by`s there into here, and reworded the `Co-authored-by` into `Co-developed-by`. ] Link: https://lore.kernel.org/r/20230408122429.1103522-5-y86-dev@protonmail.com [1] Co-developed-by: Benno Lossin Signed-off-by: Benno Lossin Signed-off-by: Asahi Lina Reviewed-by: Gary Guo Reviewed-by: Wedson Almeida Filho Reviewed-by: Andreas Hindborg Reviewed-by: Alice Ryhl Link: https://lore.kernel.org/r/20230224-rust-arc-v2-2-5c97a865b276@asahilina.net Signed-off-by: Miguel Ojeda --- rust/kernel/sync/arc.rs | 11 +++++++++++ 1 file changed, 11 insertions(+) (limited to 'rust') diff --git a/rust/kernel/sync/arc.rs b/rust/kernel/sync/arc.rs index 4ab9b280cb3d..8ce6d6bf478e 100644 --- a/rust/kernel/sync/arc.rs +++ b/rust/kernel/sync/arc.rs @@ -492,6 +492,17 @@ impl UniqueArc> { /// Converts a `UniqueArc>` into a `UniqueArc` by writing a value into it. pub fn write(mut self, value: T) -> UniqueArc { self.deref_mut().write(value); + // SAFETY: We just wrote the value to be initialized. + unsafe { self.assume_init() } + } + + /// Unsafely assume that `self` is initialized. + /// + /// # Safety + /// + /// The caller guarantees that the value behind this pointer has been initialized. It is + /// *immediate* UB to call this when the value is not initialized. + pub unsafe fn assume_init(self) -> UniqueArc { let inner = ManuallyDrop::new(self).inner.ptr; UniqueArc { // SAFETY: The new `Arc` is taking over `ptr` from `self.inner` (which won't be -- cgit v1.2.3 From 46384d0990bf99ed8b597e8794ea581e2a647710 Mon Sep 17 00:00:00 2001 From: Asahi Lina Date: Mon, 3 Apr 2023 18:48:10 +0900 Subject: rust: error: Rename to_kernel_errno() -> to_errno() This is kernel code, so specifying "kernel" is redundant. Let's simplify things and just call it to_errno(). Reviewed-by: Gary Guo Reviewed-by: Martin Rodriguez Reboredo Signed-off-by: Asahi Lina Link: https://lore.kernel.org/r/20230224-rust-error-v3-1-03779bddc02b@asahilina.net Signed-off-by: Miguel Ojeda --- rust/kernel/error.rs | 2 +- rust/macros/module.rs | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) (limited to 'rust') diff --git a/rust/kernel/error.rs b/rust/kernel/error.rs index 5b9751d7ff1d..35894fa35efe 100644 --- a/rust/kernel/error.rs +++ b/rust/kernel/error.rs @@ -73,7 +73,7 @@ pub struct Error(core::ffi::c_int); impl Error { /// Returns the kernel error code. - pub fn to_kernel_errno(self) -> core::ffi::c_int { + pub fn to_errno(self) -> core::ffi::c_int { self.0 } } diff --git a/rust/macros/module.rs b/rust/macros/module.rs index 5e7ab83908a0..fb1244f8c2e6 100644 --- a/rust/macros/module.rs +++ b/rust/macros/module.rs @@ -278,7 +278,7 @@ pub(crate) fn module(ts: TokenStream) -> TokenStream { return 0; }} Err(e) => {{ - return e.to_kernel_errno(); + return e.to_errno(); }} }} }} -- cgit v1.2.3 From c7e20faa5fcad7a177cf6c306138010343dd6d3e Mon Sep 17 00:00:00 2001 From: Asahi Lina Date: Mon, 3 Apr 2023 18:48:11 +0900 Subject: rust: error: Add Error::to_ptr() This is the Rust equivalent to ERR_PTR(), for use in C callbacks. Marked as #[allow(dead_code)] for now, since it does not have any consumers yet. Reviewed-by: Martin Rodriguez Reboredo Signed-off-by: Asahi Lina Reviewed-by: Gary Guo Link: https://lore.kernel.org/r/20230224-rust-error-v3-2-03779bddc02b@asahilina.net Signed-off-by: Miguel Ojeda --- rust/helpers.c | 7 +++++++ rust/kernel/error.rs | 7 +++++++ 2 files changed, 14 insertions(+) (limited to 'rust') diff --git a/rust/helpers.c b/rust/helpers.c index 09a4d93f9d62..89f4cd1e0df3 100644 --- a/rust/helpers.c +++ b/rust/helpers.c @@ -20,6 +20,7 @@ #include #include +#include #include __noreturn void rust_helper_BUG(void) @@ -46,6 +47,12 @@ bool rust_helper_refcount_dec_and_test(refcount_t *r) } EXPORT_SYMBOL_GPL(rust_helper_refcount_dec_and_test); +__force void *rust_helper_ERR_PTR(long err) +{ + return ERR_PTR(err); +} +EXPORT_SYMBOL_GPL(rust_helper_ERR_PTR); + /* * We use `bindgen`'s `--size_t-is-usize` option to bind the C `size_t` type * as the Rust `usize` type, so we can use it in contexts where Rust diff --git a/rust/kernel/error.rs b/rust/kernel/error.rs index 35894fa35efe..154d0ca6e2dc 100644 --- a/rust/kernel/error.rs +++ b/rust/kernel/error.rs @@ -76,6 +76,13 @@ impl Error { pub fn to_errno(self) -> core::ffi::c_int { self.0 } + + /// Returns the error encoded as a pointer. + #[allow(dead_code)] + pub(crate) fn to_ptr(self) -> *mut T { + // SAFETY: self.0 is a valid error due to its invariant. + unsafe { bindings::ERR_PTR(self.0.into()) as *mut _ } + } } impl From for Error { -- cgit v1.2.3 From 6551a7fe0acbbc816802350414b37d9b42daccc8 Mon Sep 17 00:00:00 2001 From: Miguel Ojeda Date: Mon, 3 Apr 2023 18:48:12 +0900 Subject: rust: error: Add Error::from_errno{_unchecked}() Add a function to create `Error` values out of a kernel error return, which safely upholds the invariant that the error code is well-formed (negative and greater than -MAX_ERRNO). If a malformed code is passed in, it will be converted to EINVAL. Lina: Imported from rust-for-linux/rust as authored by Miguel and Fox with refactoring from Wedson, renamed from_kernel_errno() to from_errno(). Co-developed-by: Fox Chen Signed-off-by: Fox Chen Co-developed-by: Wedson Almeida Filho Signed-off-by: Wedson Almeida Filho Signed-off-by: Miguel Ojeda Reviewed-by: Andreas Hindborg Reviewed-by: Gary Guo Reviewed-by: Martin Rodriguez Reboredo Signed-off-by: Asahi Lina Link: https://lore.kernel.org/r/20230224-rust-error-v3-3-03779bddc02b@asahilina.net [ Mark the new associated functions as `#[allow(dead_code)]`. ] Signed-off-by: Miguel Ojeda --- rust/kernel/error.rs | 32 ++++++++++++++++++++++++++++++++ 1 file changed, 32 insertions(+) (limited to 'rust') diff --git a/rust/kernel/error.rs b/rust/kernel/error.rs index 154d0ca6e2dc..0223d48ab43d 100644 --- a/rust/kernel/error.rs +++ b/rust/kernel/error.rs @@ -72,6 +72,38 @@ pub mod code { pub struct Error(core::ffi::c_int); impl Error { + /// Creates an [`Error`] from a kernel error code. + /// + /// It is a bug to pass an out-of-range `errno`. `EINVAL` would + /// be returned in such a case. + #[allow(dead_code)] + pub(crate) fn from_errno(errno: core::ffi::c_int) -> Error { + if errno < -(bindings::MAX_ERRNO as i32) || errno >= 0 { + // TODO: Make it a `WARN_ONCE` once available. + crate::pr_warn!( + "attempted to create `Error` with out of range `errno`: {}", + errno + ); + return code::EINVAL; + } + + // INVARIANT: The check above ensures the type invariant + // will hold. + Error(errno) + } + + /// Creates an [`Error`] from a kernel error code. + /// + /// # Safety + /// + /// `errno` must be within error code range (i.e. `>= -MAX_ERRNO && < 0`). + #[allow(dead_code)] + unsafe fn from_errno_unchecked(errno: core::ffi::c_int) -> Error { + // INVARIANT: The contract ensures the type invariant + // will hold. + Error(errno) + } + /// Returns the kernel error code. pub fn to_errno(self) -> core::ffi::c_int { self.0 -- cgit v1.2.3 From 086fbfa3b328901fa8b369093ba468864e20544e Mon Sep 17 00:00:00 2001 From: Wedson Almeida Filho Date: Mon, 3 Apr 2023 18:48:13 +0900 Subject: rust: error: Add to_result() helper Add a to_result() helper to convert kernel C return values to a Rust Result, mapping >=0 values to Ok(()) and negative values to Err(...), with Error::from_errno() ensuring that the errno is within range. Lina: Imported from rust-for-linux/rust, originally developed by Wedson as part of the AMBA device driver support. Signed-off-by: Wedson Almeida Filho Reviewed-by: Andreas Hindborg Reviewed-by: Gary Guo Reviewed-by: Martin Rodriguez Reboredo Signed-off-by: Asahi Lina Link: https://lore.kernel.org/r/20230224-rust-error-v3-4-03779bddc02b@asahilina.net [ Add a removal of `#[allow(dead_code)]`. ] Signed-off-by: Miguel Ojeda --- rust/kernel/error.rs | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) (limited to 'rust') diff --git a/rust/kernel/error.rs b/rust/kernel/error.rs index 0223d48ab43d..7e25871063df 100644 --- a/rust/kernel/error.rs +++ b/rust/kernel/error.rs @@ -76,7 +76,6 @@ impl Error { /// /// It is a bug to pass an out-of-range `errno`. `EINVAL` would /// be returned in such a case. - #[allow(dead_code)] pub(crate) fn from_errno(errno: core::ffi::c_int) -> Error { if errno < -(bindings::MAX_ERRNO as i32) || errno >= 0 { // TODO: Make it a `WARN_ONCE` once available. @@ -180,3 +179,13 @@ impl From for Error { /// it should still be modeled as returning a `Result` rather than /// just an [`Error`]. pub type Result = core::result::Result; + +/// Converts an integer as returned by a C kernel function to an error if it's negative, and +/// `Ok(())` otherwise. +pub fn to_result(err: core::ffi::c_int) -> Result { + if err < 0 { + Err(Error::from_errno(err)) + } else { + Ok(()) + } +} -- cgit v1.2.3 From 752417b3f0e7721f1d630f40da22d57e0dae043e Mon Sep 17 00:00:00 2001 From: Sven Van Asbroeck Date: Mon, 3 Apr 2023 18:48:14 +0900 Subject: rust: error: Add a helper to convert a C ERR_PTR to a `Result` Some kernel C API functions return a pointer which embeds an optional `errno`. Callers are supposed to check the returned pointer with `IS_ERR()` and if this returns `true`, retrieve the `errno` using `PTR_ERR()`. Create a Rust helper function to implement the Rust equivalent: transform a `*mut T` to `Result<*mut T>`. Lina: Imported from rust-for-linux/linux, with subsequent refactoring and contributions squashed in and attributed below. Renamed the function to from_err_ptr(). Co-developed-by: Boqun Feng Signed-off-by: Boqun Feng Co-developed-by: Miguel Ojeda Signed-off-by: Miguel Ojeda Co-developed-by: Fox Chen Signed-off-by: Fox Chen Co-developed-by: Gary Guo Signed-off-by: Gary Guo Signed-off-by: Sven Van Asbroeck Reviewed-by: Martin Rodriguez Reboredo Signed-off-by: Asahi Lina Link: https://lore.kernel.org/r/20230224-rust-error-v3-5-03779bddc02b@asahilina.net [ Add a removal of `#[allow(dead_code)]`. ] Signed-off-by: Miguel Ojeda --- rust/helpers.c | 12 ++++++++++++ rust/kernel/error.rs | 50 +++++++++++++++++++++++++++++++++++++++++++++++++- 2 files changed, 61 insertions(+), 1 deletion(-) (limited to 'rust') diff --git a/rust/helpers.c b/rust/helpers.c index 89f4cd1e0df3..04b9be46e887 100644 --- a/rust/helpers.c +++ b/rust/helpers.c @@ -53,6 +53,18 @@ __force void *rust_helper_ERR_PTR(long err) } EXPORT_SYMBOL_GPL(rust_helper_ERR_PTR); +bool rust_helper_IS_ERR(__force const void *ptr) +{ + return IS_ERR(ptr); +} +EXPORT_SYMBOL_GPL(rust_helper_IS_ERR); + +long rust_helper_PTR_ERR(__force const void *ptr) +{ + return PTR_ERR(ptr); +} +EXPORT_SYMBOL_GPL(rust_helper_PTR_ERR); + /* * We use `bindgen`'s `--size_t-is-usize` option to bind the C `size_t` type * as the Rust `usize` type, so we can use it in contexts where Rust diff --git a/rust/kernel/error.rs b/rust/kernel/error.rs index 7e25871063df..67637b874267 100644 --- a/rust/kernel/error.rs +++ b/rust/kernel/error.rs @@ -96,7 +96,6 @@ impl Error { /// # Safety /// /// `errno` must be within error code range (i.e. `>= -MAX_ERRNO && < 0`). - #[allow(dead_code)] unsafe fn from_errno_unchecked(errno: core::ffi::c_int) -> Error { // INVARIANT: The contract ensures the type invariant // will hold. @@ -189,3 +188,52 @@ pub fn to_result(err: core::ffi::c_int) -> Result { Ok(()) } } + +/// Transform a kernel "error pointer" to a normal pointer. +/// +/// Some kernel C API functions return an "error pointer" which optionally +/// embeds an `errno`. Callers are supposed to check the returned pointer +/// for errors. This function performs the check and converts the "error pointer" +/// to a normal pointer in an idiomatic fashion. +/// +/// # Examples +/// +/// ```ignore +/// # use kernel::from_err_ptr; +/// # use kernel::bindings; +/// fn devm_platform_ioremap_resource( +/// pdev: &mut PlatformDevice, +/// index: u32, +/// ) -> Result<*mut core::ffi::c_void> { +/// // SAFETY: FFI call. +/// unsafe { +/// from_err_ptr(bindings::devm_platform_ioremap_resource( +/// pdev.to_ptr(), +/// index, +/// )) +/// } +/// } +/// ``` +// TODO: Remove `dead_code` marker once an in-kernel client is available. +#[allow(dead_code)] +pub(crate) fn from_err_ptr(ptr: *mut T) -> Result<*mut T> { + // CAST: Casting a pointer to `*const core::ffi::c_void` is always valid. + let const_ptr: *const core::ffi::c_void = ptr.cast(); + // SAFETY: The FFI function does not deref the pointer. + if unsafe { bindings::IS_ERR(const_ptr) } { + // SAFETY: The FFI function does not deref the pointer. + let err = unsafe { bindings::PTR_ERR(const_ptr) }; + // CAST: If `IS_ERR()` returns `true`, + // then `PTR_ERR()` is guaranteed to return a + // negative value greater-or-equal to `-bindings::MAX_ERRNO`, + // which always fits in an `i16`, as per the invariant above. + // And an `i16` always fits in an `i32`. So casting `err` to + // an `i32` can never overflow, and is always valid. + // + // SAFETY: `IS_ERR()` ensures `err` is a + // negative value greater-or-equal to `-bindings::MAX_ERRNO`. + #[allow(clippy::unnecessary_cast)] + return Err(unsafe { Error::from_errno_unchecked(err as core::ffi::c_int) }); + } + Ok(ptr) +} -- cgit v1.2.3 From ef4dc4cc7001e9cce8a3b556362171648be9ad92 Mon Sep 17 00:00:00 2001 From: Wedson Almeida Filho Date: Mon, 3 Apr 2023 18:48:15 +0900 Subject: rust: error: Add from_result() helper Add a helper function to easily return C result codes from a Rust function that calls functions which return a Result. Lina: Imported from rust-for-linux/rust, originally developed by Wedson as part of file_operations.rs. Added the allow() flags since there is no user in the kernel crate yet and fixed a typo in a comment. Replaced the macro with a function taking a closure, per discussion on the ML. Co-developed-by: Fox Chen Signed-off-by: Fox Chen Co-developed-by: Miguel Ojeda Signed-off-by: Miguel Ojeda Signed-off-by: Wedson Almeida Filho Reviewed-by: Martin Rodriguez Reboredo Signed-off-by: Asahi Lina Link: https://lore.kernel.org/r/20230224-rust-error-v3-6-03779bddc02b@asahilina.net Signed-off-by: Miguel Ojeda --- rust/kernel/error.rs | 39 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 39 insertions(+) (limited to 'rust') diff --git a/rust/kernel/error.rs b/rust/kernel/error.rs index 67637b874267..5f4114b30b94 100644 --- a/rust/kernel/error.rs +++ b/rust/kernel/error.rs @@ -237,3 +237,42 @@ pub(crate) fn from_err_ptr(ptr: *mut T) -> Result<*mut T> { } Ok(ptr) } + +/// Calls a closure returning a [`crate::error::Result`] and converts the result to +/// a C integer result. +/// +/// This is useful when calling Rust functions that return [`crate::error::Result`] +/// from inside `extern "C"` functions that need to return an integer error result. +/// +/// `T` should be convertible from an `i16` via `From`. +/// +/// # Examples +/// +/// ```ignore +/// # use kernel::from_result; +/// # use kernel::bindings; +/// unsafe extern "C" fn probe_callback( +/// pdev: *mut bindings::platform_device, +/// ) -> core::ffi::c_int { +/// from_result(|| { +/// let ptr = devm_alloc(pdev)?; +/// bindings::platform_set_drvdata(pdev, ptr); +/// Ok(0) +/// }) +/// } +/// ``` +// TODO: Remove `dead_code` marker once an in-kernel client is available. +#[allow(dead_code)] +pub(crate) fn from_result(f: F) -> T +where + T: From, + F: FnOnce() -> Result, +{ + match f() { + Ok(v) => v, + // NO-OVERFLOW: negative `errno`s are no smaller than `-bindings::MAX_ERRNO`, + // `-bindings::MAX_ERRNO` fits in an `i16` as per invariant above, + // therefore a negative `errno` always fits in an `i16` and will not overflow. + Err(e) => T::from(e.to_errno() as i16), + } +} -- cgit v1.2.3 From 2d19d369c0c6dade11b8e3448c158655dbaa7b77 Mon Sep 17 00:00:00 2001 From: Benno Lossin Date: Sat, 8 Apr 2023 12:25:18 +0000 Subject: rust: enable the `pin_macro` feature This feature enables the use of the `pin!` macro for the `stack_pin_init!` macro. This feature is already stabilized in Rust version 1.68. Signed-off-by: Benno Lossin Reviewed-by: Alice Ryhl Reviewed-by: Gary Guo Reviewed-by: Andreas Hindborg Acked-by: Boqun Feng Link: https://lore.kernel.org/r/20230408122429.1103522-2-y86-dev@protonmail.com Signed-off-by: Miguel Ojeda --- rust/kernel/lib.rs | 1 + 1 file changed, 1 insertion(+) (limited to 'rust') diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs index 1118cd3e0b5f..518559a0767e 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -18,6 +18,7 @@ #![feature(dispatch_from_dyn)] #![feature(generic_associated_types)] #![feature(new_uninit)] +#![feature(pin_macro)] #![feature(receiver_trait)] #![feature(unsize)] -- cgit v1.2.3 From 70a21e54a42232f1056db7f05a194f56e03e7d3e Mon Sep 17 00:00:00 2001 From: Gary Guo Date: Sat, 8 Apr 2023 12:25:23 +0000 Subject: rust: macros: add `quote!` macro Add the `quote!` macro for creating `TokenStream`s directly via the given Rust tokens. It also supports repetitions using iterators. It will be used by the pin-init API proc-macros to generate code. Signed-off-by: Gary Guo Signed-off-by: Benno Lossin Reviewed-by: Andreas Hindborg Reviewed-by: Alice Ryhl Link: https://lore.kernel.org/r/20230408122429.1103522-3-y86-dev@protonmail.com Signed-off-by: Miguel Ojeda --- rust/macros/lib.rs | 2 + rust/macros/quote.rs | 145 +++++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 147 insertions(+) create mode 100644 rust/macros/quote.rs (limited to 'rust') diff --git a/rust/macros/lib.rs b/rust/macros/lib.rs index c1d385e345b9..82b520f024dd 100644 --- a/rust/macros/lib.rs +++ b/rust/macros/lib.rs @@ -2,6 +2,8 @@ //! Crate for all kernel procedural macros. +#[macro_use] +mod quote; mod concat_idents; mod helpers; mod module; diff --git a/rust/macros/quote.rs b/rust/macros/quote.rs new file mode 100644 index 000000000000..94a6277182ee --- /dev/null +++ b/rust/macros/quote.rs @@ -0,0 +1,145 @@ +// SPDX-License-Identifier: Apache-2.0 OR MIT + +use proc_macro::{TokenStream, TokenTree}; + +pub(crate) trait ToTokens { + fn to_tokens(&self, tokens: &mut TokenStream); +} + +impl ToTokens for Option { + fn to_tokens(&self, tokens: &mut TokenStream) { + if let Some(v) = self { + v.to_tokens(tokens); + } + } +} + +impl ToTokens for proc_macro::Group { + fn to_tokens(&self, tokens: &mut TokenStream) { + tokens.extend([TokenTree::from(self.clone())]); + } +} + +impl ToTokens for TokenTree { + fn to_tokens(&self, tokens: &mut TokenStream) { + tokens.extend([self.clone()]); + } +} + +impl ToTokens for TokenStream { + fn to_tokens(&self, tokens: &mut TokenStream) { + tokens.extend(self.clone()); + } +} + +/// Converts tokens into [`proc_macro::TokenStream`] and performs variable interpolations with +/// the given span. +/// +/// This is a similar to the +/// [`quote_spanned!`](https://docs.rs/quote/latest/quote/macro.quote_spanned.html) macro from the +/// `quote` crate but provides only just enough functionality needed by the current `macros` crate. +#[allow(unused_macros)] +macro_rules! quote_spanned { + ($span:expr => $($tt:tt)*) => { + #[allow(clippy::vec_init_then_push)] + { + let mut tokens = ::std::vec::Vec::new(); + let span = $span; + quote_spanned!(@proc tokens span $($tt)*); + ::proc_macro::TokenStream::from_iter(tokens) + }}; + (@proc $v:ident $span:ident) => {}; + (@proc $v:ident $span:ident #$id:ident $($tt:tt)*) => { + let mut ts = ::proc_macro::TokenStream::new(); + $crate::quote::ToTokens::to_tokens(&$id, &mut ts); + $v.extend(ts); + quote_spanned!(@proc $v $span $($tt)*); + }; + (@proc $v:ident $span:ident #(#$id:ident)* $($tt:tt)*) => { + for token in $id { + let mut ts = ::proc_macro::TokenStream::new(); + $crate::quote::ToTokens::to_tokens(&token, &mut ts); + $v.extend(ts); + } + quote_spanned!(@proc $v $span $($tt)*); + }; + (@proc $v:ident $span:ident ( $($inner:tt)* ) $($tt:tt)*) => { + let mut tokens = ::std::vec::Vec::new(); + quote_spanned!(@proc tokens $span $($inner)*); + $v.push(::proc_macro::TokenTree::Group(::proc_macro::Group::new( + ::proc_macro::Delimiter::Parenthesis, + ::proc_macro::TokenStream::from_iter(tokens) + ))); + quote_spanned!(@proc $v $span $($tt)*); + }; + (@proc $v:ident $span:ident [ $($inner:tt)* ] $($tt:tt)*) => { + let mut tokens = ::std::vec::Vec::new(); + quote_spanned!(@proc tokens $span $($inner)*); + $v.push(::proc_macro::TokenTree::Group(::proc_macro::Group::new( + ::proc_macro::Delimiter::Bracket, + ::proc_macro::TokenStream::from_iter(tokens) + ))); + quote_spanned!(@proc $v $span $($tt)*); + }; + (@proc $v:ident $span:ident { $($inner:tt)* } $($tt:tt)*) => { + let mut tokens = ::std::vec::Vec::new(); + quote_spanned!(@proc tokens $span $($inner)*); + $v.push(::proc_macro::TokenTree::Group(::proc_macro::Group::new( + ::proc_macro::Delimiter::Brace, + ::proc_macro::TokenStream::from_iter(tokens) + ))); + quote_spanned!(@proc $v $span $($tt)*); + }; + (@proc $v:ident $span:ident :: $($tt:tt)*) => { + $v.push(::proc_macro::TokenTree::Punct( + ::proc_macro::Punct::new(':', ::proc_macro::Spacing::Joint) + )); + $v.push(::proc_macro::TokenTree::Punct( + ::proc_macro::Punct::new(':', ::proc_macro::Spacing::Alone) + )); + quote_spanned!(@proc $v $span $($tt)*); + }; + (@proc $v:ident $span:ident : $($tt:tt)*) => { + $v.push(::proc_macro::TokenTree::Punct( + ::proc_macro::Punct::new(':', ::proc_macro::Spacing::Alone) + )); + quote_spanned!(@proc $v $span $($tt)*); + }; + (@proc $v:ident $span:ident , $($tt:tt)*) => { + $v.push(::proc_macro::TokenTree::Punct( + ::proc_macro::Punct::new(',', ::proc_macro::Spacing::Alone) + )); + quote_spanned!(@proc $v $span $($tt)*); + }; + (@proc $v:ident $span:ident @ $($tt:tt)*) => { + $v.push(::proc_macro::TokenTree::Punct( + ::proc_macro::Punct::new('@', ::proc_macro::Spacing::Alone) + )); + quote_spanned!(@proc $v $span $($tt)*); + }; + (@proc $v:ident $span:ident ! $($tt:tt)*) => { + $v.push(::proc_macro::TokenTree::Punct( + ::proc_macro::Punct::new('!', ::proc_macro::Spacing::Alone) + )); + quote_spanned!(@proc $v $span $($tt)*); + }; + (@proc $v:ident $span:ident $id:ident $($tt:tt)*) => { + $v.push(::proc_macro::TokenTree::Ident(::proc_macro::Ident::new(stringify!($id), $span))); + quote_spanned!(@proc $v $span $($tt)*); + }; +} + +/// Converts tokens into [`proc_macro::TokenStream`] and performs variable interpolations with +/// mixed site span ([`Span::mixed_site()`]). +/// +/// This is a similar to the [`quote!`](https://docs.rs/quote/latest/quote/macro.quote.html) macro +/// from the `quote` crate but provides only just enough functionality needed by the current +/// `macros` crate. +/// +/// [`Span::mixed_site()`]: https://doc.rust-lang.org/proc_macro/struct.Span.html#method.mixed_site +#[allow(unused_macros)] +macro_rules! quote { + ($($tt:tt)*) => { + quote_spanned!(::proc_macro::Span::mixed_site() => $($tt)*) + } +} -- cgit v1.2.3 From d6dbca3592209d29c10e171224c34803805e88ca Mon Sep 17 00:00:00 2001 From: Benno Lossin Date: Sat, 8 Apr 2023 12:25:29 +0000 Subject: rust: sync: change error type of constructor functions Change the error type of the constructors of `Arc` and `UniqueArc` to be `AllocError` instead of `Error`. This makes the API more clear as to what can go wrong when calling `try_new` or its variants. Signed-off-by: Benno Lossin Reviewed-by: Andreas Hindborg Reviewed-by: Alice Ryhl Reviewed-by: Gary Guo Link: https://lore.kernel.org/r/20230408122429.1103522-4-y86-dev@protonmail.com Signed-off-by: Miguel Ojeda --- rust/kernel/sync/arc.rs | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'rust') diff --git a/rust/kernel/sync/arc.rs b/rust/kernel/sync/arc.rs index 8ce6d6bf478e..34d0e7cbe62e 100644 --- a/rust/kernel/sync/arc.rs +++ b/rust/kernel/sync/arc.rs @@ -17,11 +17,11 @@ use crate::{ bindings, - error::Result, types::{ForeignOwnable, Opaque}, }; use alloc::boxed::Box; use core::{ + alloc::AllocError, fmt, marker::{PhantomData, Unsize}, mem::{ManuallyDrop, MaybeUninit}, @@ -152,7 +152,7 @@ unsafe impl Sync for Arc {} impl Arc { /// Constructs a new reference counted instance of `T`. - pub fn try_new(contents: T) -> Result { + pub fn try_new(contents: T) -> Result { // INVARIANT: The refcount is initialised to a non-zero value. let value = ArcInner { // SAFETY: There are no safety requirements for this FFI call. @@ -472,7 +472,7 @@ pub struct UniqueArc { impl UniqueArc { /// Tries to allocate a new [`UniqueArc`] instance. - pub fn try_new(value: T) -> Result { + pub fn try_new(value: T) -> Result { Ok(Self { // INVARIANT: The newly-created object has a ref-count of 1. inner: Arc::try_new(value)?, @@ -480,7 +480,7 @@ impl UniqueArc { } /// Tries to allocate a new [`UniqueArc`] instance whose contents are not initialised yet. - pub fn try_new_uninit() -> Result>> { + pub fn try_new_uninit() -> Result>, AllocError> { Ok(UniqueArc::> { // INVARIANT: The newly-created object has a ref-count of 1. inner: Arc::try_new(MaybeUninit::uninit())?, -- cgit v1.2.3 From 3ff6e785ad99893f1d502156d23560efd30fec4d Mon Sep 17 00:00:00 2001 From: Benno Lossin Date: Sat, 8 Apr 2023 12:25:39 +0000 Subject: rust: types: add `Opaque::raw_get` This function mirrors `UnsafeCell::raw_get`. It avoids creating a reference and allows solely using raw pointers. The `pin-init` API will be using this, since uninitialized memory requires raw pointers. Signed-off-by: Benno Lossin Reviewed-by: Gary Guo Reviewed-by: Andreas Hindborg Reviewed-by: Alice Ryhl Link: https://lore.kernel.org/r/20230408122429.1103522-6-y86-dev@protonmail.com Signed-off-by: Miguel Ojeda --- rust/kernel/types.rs | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'rust') diff --git a/rust/kernel/types.rs b/rust/kernel/types.rs index 9d0fdbc55843..ff2b2fac951d 100644 --- a/rust/kernel/types.rs +++ b/rust/kernel/types.rs @@ -238,6 +238,14 @@ impl Opaque { pub fn get(&self) -> *mut T { UnsafeCell::raw_get(self.0.as_ptr()) } + + /// Gets the value behind `this`. + /// + /// This function is useful to get access to the value without creating intermediate + /// references. + pub const fn raw_get(this: *const Self) -> *mut T { + UnsafeCell::raw_get(this.cast::>()) + } } /// A sum type that always holds either a value of type `L` or `R`. -- cgit v1.2.3 From 90e53c5e70a69159ec255fec361f7dcf9cf36eae Mon Sep 17 00:00:00 2001 From: Benno Lossin Date: Sat, 8 Apr 2023 12:25:45 +0000 Subject: rust: add pin-init API core This API is used to facilitate safe pinned initialization of structs. It replaces cumbersome `unsafe` manual initialization with elegant safe macro invocations. Due to the size of this change it has been split into six commits: 1. This commit introducing the basic public interface: traits and functions to represent and create initializers. 2. Adds the `#[pin_data]`, `pin_init!`, `try_pin_init!`, `init!` and `try_init!` macros along with their internal types. 3. Adds the `InPlaceInit` trait that allows using an initializer to create an object inside of a `Box` and other smart pointers. 4. Adds the `PinnedDrop` trait and adds macro support for it in the `#[pin_data]` macro. 5. Adds the `stack_pin_init!` macro allowing to pin-initialize a struct on the stack. 6. Adds the `Zeroable` trait and `init::zeroed` function to initialize types that have `0x00` in all bytes as a valid bit pattern. -- In this section the problem that the new pin-init API solves is outlined. This message describes the entirety of the API, not just the parts introduced in this commit. For a more granular explanation and additional information on pinning and this issue, view [1]. Pinning is Rust's way of enforcing the address stability of a value. When a value gets pinned it will be impossible for safe code to move it to another location. This is done by wrapping pointers to said object with `Pin

`. This wrapper prevents safe code from creating mutable references to the object, preventing mutable access, which is needed to move the value. `Pin

` provides `unsafe` functions to circumvent this and allow modifications regardless. It is then the programmer's responsibility to uphold the pinning guarantee. Many kernel data structures require a stable address, because there are foreign pointers to them which would get invalidated by moving the structure. Since these data structures are usually embedded in structs to use them, this pinning property propagates to the container struct. Resulting in most structs in both Rust and C code needing to be pinned. So if we want to have a `mutex` field in a Rust struct, this struct also needs to be pinned, because a `mutex` contains a `list_head`. Additionally initializing a `list_head` requires already having the final memory location available, because it is initialized by pointing it to itself. But this presents another challenge in Rust: values have to be initialized at all times. There is the `MaybeUninit` wrapper type, which allows handling uninitialized memory, but this requires using the `unsafe` raw pointers and a casting the type to the initialized variant. This problem gets exacerbated when considering encapsulation and the normal safety requirements of Rust code. The fields of the Rust `Mutex` should not be accessible to normal driver code. After all if anyone can modify the fields, there is no way to ensure the invariants of the `Mutex` are upheld. But if the fields are inaccessible, then initialization of a `Mutex` needs to be somehow achieved via a function or a macro. Because the `Mutex` must be pinned in memory, the function cannot return it by value. It also cannot allocate a `Box` to put the `Mutex` into, because that is an unnecessary allocation and indirection which would hurt performance. The solution in the rust tree (e.g. this commit: [2]) that is replaced by this API is to split this function into two parts: 1. A `new` function that returns a partially initialized `Mutex`, 2. An `init` function that requires the `Mutex` to be pinned and that fully initializes the `Mutex`. Both of these functions have to be marked `unsafe`, since a call to `new` needs to be accompanied with a call to `init`, otherwise using the `Mutex` could result in UB. And because calling `init` twice also is not safe. While `Mutex` initialization cannot fail, other structs might also have to allocate memory, which would result in conditional successful initialization requiring even more manual accommodation work. Combine this with the problem of pin-projections -- the way of accessing fields of a pinned struct -- which also have an `unsafe` API, pinned initialization is riddled with `unsafe` resulting in very poor ergonomics. Not only that, but also having to call two functions possibly multiple lines apart makes it very easy to forget it outright or during refactoring. Here is an example of the current way of initializing a struct with two synchronization primitives (see [3] for the full example): struct SharedState { state_changed: CondVar, inner: Mutex, } impl SharedState { fn try_new() -> Result> { let mut state = Pin::from(UniqueArc::try_new(Self { // SAFETY: `condvar_init!` is called below. state_changed: unsafe { CondVar::new() }, // SAFETY: `mutex_init!` is called below. inner: unsafe { Mutex::new(SharedStateInner { token_count: 0 }) }, })?); // SAFETY: `state_changed` is pinned when `state` is. let pinned = unsafe { state.as_mut().map_unchecked_mut(|s| &mut s.state_changed) }; kernel::condvar_init!(pinned, "SharedState::state_changed"); // SAFETY: `inner` is pinned when `state` is. let pinned = unsafe { state.as_mut().map_unchecked_mut(|s| &mut s.inner) }; kernel::mutex_init!(pinned, "SharedState::inner"); Ok(state.into()) } } The pin-init API of this patch solves this issue by providing a comprehensive solution comprised of macros and traits. Here is the example from above using the pin-init API: #[pin_data] struct SharedState { #[pin] state_changed: CondVar, #[pin] inner: Mutex, } impl SharedState { fn new() -> impl PinInit { pin_init!(Self { state_changed <- new_condvar!("SharedState::state_changed"), inner <- new_mutex!( SharedStateInner { token_count: 0 }, "SharedState::inner", ), }) } } Notably the way the macro is used here requires no `unsafe` and thus comes with the usual Rust promise of safe code not introducing any memory violations. Additionally it is now up to the caller of `new()` to decide the memory location of the `SharedState`. They can choose at the moment `Arc`, `Box` or the stack. -- The API has the following architecture: 1. Initializer traits `PinInit` and `Init` that act like closures. 2. Macros to create these initializer traits safely. 3. Functions to allow manually writing initializers. The initializers (an `impl PinInit`) receive a raw pointer pointing to uninitialized memory and their job is to fully initialize a `T` at that location. If initialization fails, they return an error (`E`) by value. This way of initializing cannot be safely exposed to the user, since it relies upon these properties outside of the control of the trait: - the memory location (slot) needs to be valid memory, - if initialization fails, the slot should not be read from, - the value in the slot should be pinned, so it cannot move and the memory cannot be deallocated until the value is dropped. This is why using an initializer is facilitated by another trait that ensures these requirements. These initializers can be created manually by just supplying a closure that fulfills the same safety requirements as `PinInit`. But this is an `unsafe` operation. To allow safe initializer creation, the `pin_init!` is provided along with three other variants: `try_pin_init!`, `try_init!` and `init!`. These take a modified struct initializer as a parameter and generate a closure that initializes the fields in sequence. The macros take great care in upholding the safety requirements: - A shadowed struct type is used as the return type of the closure instead of `()`. This is to prevent early returns, as these would prevent full initialization. - To ensure every field is only initialized once, a normal struct initializer is placed in unreachable code. The type checker will emit errors if a field is missing or specified multiple times. - When initializing a field fails, the whole initializer will fail and automatically drop fields that have been initialized earlier. - Only the correct initializer type is allowed for unpinned fields. You cannot use a `impl PinInit` to initialize a structurally not pinned field. To ensure the last point, an additional macro `#[pin_data]` is needed. This macro annotates the struct itself and the user specifies structurally pinned and not pinned fields. Because dropping a pinned struct is also not allowed to break the pinning invariants, another macro attribute `#[pinned_drop]` is needed. This macro is introduced in a following commit. These two macros also have mechanisms to ensure the overall safety of the API. Additionally, they utilize a combined proc-macro, declarative macro design: first a proc-macro enables the outer attribute syntax `#[...]` and does some important pre-parsing. Notably this prepares the generics such that the declarative macro can handle them using token trees. Then the actual parsing of the structure and the emission of code is handled by a declarative macro. For pin-projections the crates `pin-project` [4] and `pin-project-lite` [5] had been considered, but were ultimately rejected: - `pin-project` depends on `syn` [6] which is a very big dependency, around 50k lines of code. - `pin-project-lite` is a more reasonable 5k lines of code, but contains a very complex declarative macro to parse generics. On top of that it would require modification that would need to be maintained independently. Link: https://rust-for-linux.com/the-safe-pinned-initialization-problem [1] Link: https://github.com/Rust-for-Linux/linux/tree/0a04dc4ddd671efb87eef54dde0fb38e9074f4be [2] Link: https://github.com/Rust-for-Linux/linux/blob/f509ede33fc10a07eba3da14aa00302bd4b5dddd/samples/rust/rust_miscdev.rs [3] Link: https://crates.io/crates/pin-project [4] Link: https://crates.io/crates/pin-project-lite [5] Link: https://crates.io/crates/syn [6] Co-developed-by: Gary Guo Signed-off-by: Gary Guo Signed-off-by: Benno Lossin Reviewed-by: Alice Ryhl Reviewed-by: Wedson Almeida Filho Reviewed-by: Andreas Hindborg Link: https://lore.kernel.org/r/20230408122429.1103522-7-y86-dev@protonmail.com Signed-off-by: Miguel Ojeda --- rust/kernel/init.rs | 187 +++++++++++++++++++++++++++++++++++++++++ rust/kernel/init/__internal.rs | 33 ++++++++ rust/kernel/lib.rs | 6 ++ 3 files changed, 226 insertions(+) create mode 100644 rust/kernel/init.rs create mode 100644 rust/kernel/init/__internal.rs (limited to 'rust') diff --git a/rust/kernel/init.rs b/rust/kernel/init.rs new file mode 100644 index 000000000000..d041f0daf71e --- /dev/null +++ b/rust/kernel/init.rs @@ -0,0 +1,187 @@ +// SPDX-License-Identifier: Apache-2.0 OR MIT + +//! API to safely and fallibly initialize pinned `struct`s using in-place constructors. +//! +//! It also allows in-place initialization of big `struct`s that would otherwise produce a stack +//! overflow. +//! +//! Most `struct`s from the [`sync`] module need to be pinned, because they contain self-referential +//! `struct`s from C. [Pinning][pinning] is Rust's way of ensuring data does not move. +//! +//! # Overview +//! +//! To initialize a `struct` with an in-place constructor you will need two things: +//! - an in-place constructor, +//! - a memory location that can hold your `struct`. +//! +//! To get an in-place constructor there are generally two options: +//! - a custom function/macro returning an in-place constructor provided by someone else, +//! - using the unsafe function [`pin_init_from_closure()`] to manually create an initializer. +//! +//! Aside from pinned initialization, this API also supports in-place construction without pinning, +//! the macros/types/functions are generally named like the pinned variants without the `pin` +//! prefix. +//! +//! [`sync`]: kernel::sync +//! [pinning]: https://doc.rust-lang.org/std/pin/index.html +//! [structurally pinned fields]: +//! https://doc.rust-lang.org/std/pin/index.html#pinning-is-structural-for-field +//! [`Arc`]: crate::sync::Arc +//! [`impl PinInit`]: PinInit +//! [`impl PinInit`]: PinInit +//! [`impl Init`]: Init +//! [`Opaque`]: kernel::types::Opaque +//! [`pin_data`]: ::macros::pin_data +//! [`UniqueArc`]: kernel::sync::UniqueArc +//! [`Box`]: alloc::boxed::Box + +use core::{convert::Infallible, marker::PhantomData, mem::MaybeUninit}; + +#[doc(hidden)] +pub mod __internal; + +/// A pin-initializer for the type `T`. +/// +/// To use this initializer, you will need a suitable memory location that can hold a `T`. This can +/// be [`Box`], [`Arc`], [`UniqueArc`]. +/// +/// Also see the [module description](self). +/// +/// # Safety +/// +/// When implementing this type you will need to take great care. Also there are probably very few +/// cases where a manual implementation is necessary. Use [`pin_init_from_closure`] where possible. +/// +/// The [`PinInit::__pinned_init`] function +/// - returns `Ok(())` if it initialized every field of `slot`, +/// - returns `Err(err)` if it encountered an error and then cleaned `slot`, this means: +/// - `slot` can be deallocated without UB occurring, +/// - `slot` does not need to be dropped, +/// - `slot` is not partially initialized. +/// - while constructing the `T` at `slot` it upholds the pinning invariants of `T`. +/// +/// [`Arc`]: crate::sync::Arc +/// [`Arc::pin_init`]: crate::sync::Arc::pin_init +/// [`UniqueArc`]: kernel::sync::UniqueArc +/// [`Box`]: alloc::boxed::Box +#[must_use = "An initializer must be used in order to create its value."] +pub unsafe trait PinInit: Sized { + /// Initializes `slot`. + /// + /// # Safety + /// + /// - `slot` is a valid pointer to uninitialized memory. + /// - the caller does not touch `slot` when `Err` is returned, they are only permitted to + /// deallocate. + /// - `slot` will not move until it is dropped, i.e. it will be pinned. + unsafe fn __pinned_init(self, slot: *mut T) -> Result<(), E>; +} + +/// An initializer for `T`. +/// +/// To use this initializer, you will need a suitable memory location that can hold a `T`. This can +/// be [`Box`], [`Arc`], [`UniqueArc`]. Because [`PinInit`] is a super trait, you can +/// use every function that takes it as well. +/// +/// Also see the [module description](self). +/// +/// # Safety +/// +/// When implementing this type you will need to take great care. Also there are probably very few +/// cases where a manual implementation is necessary. Use [`init_from_closure`] where possible. +/// +/// The [`Init::__init`] function +/// - returns `Ok(())` if it initialized every field of `slot`, +/// - returns `Err(err)` if it encountered an error and then cleaned `slot`, this means: +/// - `slot` can be deallocated without UB occurring, +/// - `slot` does not need to be dropped, +/// - `slot` is not partially initialized. +/// - while constructing the `T` at `slot` it upholds the pinning invariants of `T`. +/// +/// The `__pinned_init` function from the supertrait [`PinInit`] needs to execute the exact same +/// code as `__init`. +/// +/// Contrary to its supertype [`PinInit`] the caller is allowed to +/// move the pointee after initialization. +/// +/// [`Arc`]: crate::sync::Arc +/// [`UniqueArc`]: kernel::sync::UniqueArc +/// [`Box`]: alloc::boxed::Box +#[must_use = "An initializer must be used in order to create its value."] +pub unsafe trait Init: Sized { + /// Initializes `slot`. + /// + /// # Safety + /// + /// - `slot` is a valid pointer to uninitialized memory. + /// - the caller does not touch `slot` when `Err` is returned, they are only permitted to + /// deallocate. + unsafe fn __init(self, slot: *mut T) -> Result<(), E>; +} + +// SAFETY: Every in-place initializer can also be used as a pin-initializer. +unsafe impl PinInit for I +where + I: Init, +{ + unsafe fn __pinned_init(self, slot: *mut T) -> Result<(), E> { + // SAFETY: `__init` meets the same requirements as `__pinned_init`, except that it does not + // require `slot` to not move after init. + unsafe { self.__init(slot) } + } +} + +/// Creates a new [`PinInit`] from the given closure. +/// +/// # Safety +/// +/// The closure: +/// - returns `Ok(())` if it initialized every field of `slot`, +/// - returns `Err(err)` if it encountered an error and then cleaned `slot`, this means: +/// - `slot` can be deallocated without UB occurring, +/// - `slot` does not need to be dropped, +/// - `slot` is not partially initialized. +/// - may assume that the `slot` does not move if `T: !Unpin`, +/// - while constructing the `T` at `slot` it upholds the pinning invariants of `T`. +#[inline] +pub const unsafe fn pin_init_from_closure( + f: impl FnOnce(*mut T) -> Result<(), E>, +) -> impl PinInit { + __internal::InitClosure(f, PhantomData) +} + +/// Creates a new [`Init`] from the given closure. +/// +/// # Safety +/// +/// The closure: +/// - returns `Ok(())` if it initialized every field of `slot`, +/// - returns `Err(err)` if it encountered an error and then cleaned `slot`, this means: +/// - `slot` can be deallocated without UB occurring, +/// - `slot` does not need to be dropped, +/// - `slot` is not partially initialized. +/// - the `slot` may move after initialization. +/// - while constructing the `T` at `slot` it upholds the pinning invariants of `T`. +#[inline] +pub const unsafe fn init_from_closure( + f: impl FnOnce(*mut T) -> Result<(), E>, +) -> impl Init { + __internal::InitClosure(f, PhantomData) +} + +/// An initializer that leaves the memory uninitialized. +/// +/// The initializer is a no-op. The `slot` memory is not changed. +#[inline] +pub fn uninit() -> impl Init, E> { + // SAFETY: The memory is allowed to be uninitialized. + unsafe { init_from_closure(|_| Ok(())) } +} + +// SAFETY: Every type can be initialized by-value. +unsafe impl Init for T { + unsafe fn __init(self, slot: *mut T) -> Result<(), Infallible> { + unsafe { slot.write(self) }; + Ok(()) + } +} diff --git a/rust/kernel/init/__internal.rs b/rust/kernel/init/__internal.rs new file mode 100644 index 000000000000..08cbb5333438 --- /dev/null +++ b/rust/kernel/init/__internal.rs @@ -0,0 +1,33 @@ +// SPDX-License-Identifier: Apache-2.0 OR MIT + +//! This module contains API-internal items for pin-init. +//! +//! These items must not be used outside of +//! - `kernel/init.rs` +//! - `macros/pin_data.rs` +//! - `macros/pinned_drop.rs` + +use super::*; + +/// See the [nomicon] for what subtyping is. See also [this table]. +/// +/// [nomicon]: https://doc.rust-lang.org/nomicon/subtyping.html +/// [this table]: https://doc.rust-lang.org/nomicon/phantom-data.html#table-of-phantomdata-patterns +type Invariant = PhantomData *mut T>; + +/// This is the module-internal type implementing `PinInit` and `Init`. It is unsafe to create this +/// type, since the closure needs to fulfill the same safety requirement as the +/// `__pinned_init`/`__init` functions. +pub(crate) struct InitClosure(pub(crate) F, pub(crate) Invariant<(E, T)>); + +// SAFETY: While constructing the `InitClosure`, the user promised that it upholds the +// `__init` invariants. +unsafe impl Init for InitClosure +where + F: FnOnce(*mut T) -> Result<(), E>, +{ + #[inline] + unsafe fn __init(self, slot: *mut T) -> Result<(), E> { + (self.0)(slot) + } +} diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs index 518559a0767e..821bd067151c 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -16,6 +16,7 @@ #![feature(coerce_unsized)] #![feature(core_ffi_c)] #![feature(dispatch_from_dyn)] +#![feature(explicit_generic_args_with_impl_trait)] #![feature(generic_associated_types)] #![feature(new_uninit)] #![feature(pin_macro)] @@ -27,11 +28,16 @@ #[cfg(not(CONFIG_RUST))] compile_error!("Missing kernel configuration for conditional compilation"); +#[allow(unused_extern_crates)] +// Allow proc-macros to refer to `::kernel` inside the `kernel` crate (this crate). +extern crate self as kernel; + #[cfg(not(test))] #[cfg(not(testlib))] mod allocator; mod build_assert; pub mod error; +pub mod init; pub mod prelude; pub mod print; mod static_assert; -- cgit v1.2.3 From fc6c6baa1f40ded13e539d0c1a17bcefc00abad9 Mon Sep 17 00:00:00 2001 From: Benno Lossin Date: Sat, 8 Apr 2023 12:25:51 +0000 Subject: rust: init: add initialization macros Add the following initializer macros: - `#[pin_data]` to annotate structurally pinned fields of structs, needed for `pin_init!` and `try_pin_init!` to select the correct initializer of fields. - `pin_init!` create a pin-initializer for a struct with the `Infallible` error type. - `try_pin_init!` create a pin-initializer for a struct with a custom error type (`kernel::error::Error` is the default). - `init!` create an in-place-initializer for a struct with the `Infallible` error type. - `try_init!` create an in-place-initializer for a struct with a custom error type (`kernel::error::Error` is the default). Also add their needed internal helper traits and structs. Co-developed-by: Gary Guo Signed-off-by: Gary Guo Signed-off-by: Benno Lossin Reviewed-by: Alice Ryhl Reviewed-by: Andreas Hindborg Link: https://lore.kernel.org/r/20230408122429.1103522-8-y86-dev@protonmail.com [ Fixed three typos. ] Signed-off-by: Miguel Ojeda --- rust/kernel/init.rs | 807 ++++++++++++++++++++++++++++++++++++++++- rust/kernel/init/__internal.rs | 130 +++++++ rust/kernel/init/macros.rs | 707 ++++++++++++++++++++++++++++++++++++ rust/macros/lib.rs | 29 ++ rust/macros/pin_data.rs | 79 ++++ rust/macros/quote.rs | 2 - 6 files changed, 1747 insertions(+), 7 deletions(-) create mode 100644 rust/kernel/init/macros.rs create mode 100644 rust/macros/pin_data.rs (limited to 'rust') diff --git a/rust/kernel/init.rs b/rust/kernel/init.rs index d041f0daf71e..ecef0376d726 100644 --- a/rust/kernel/init.rs +++ b/rust/kernel/init.rs @@ -14,7 +14,8 @@ //! - an in-place constructor, //! - a memory location that can hold your `struct`. //! -//! To get an in-place constructor there are generally two options: +//! To get an in-place constructor there are generally three options: +//! - directly creating an in-place constructor using the [`pin_init!`] macro, //! - a custom function/macro returning an in-place constructor provided by someone else, //! - using the unsafe function [`pin_init_from_closure()`] to manually create an initializer. //! @@ -22,6 +23,87 @@ //! the macros/types/functions are generally named like the pinned variants without the `pin` //! prefix. //! +//! # Examples +//! +//! ## Using the [`pin_init!`] macro +//! +//! If you want to use [`PinInit`], then you will have to annotate your `struct` with +//! `#[`[`pin_data`]`]`. It is a macro that uses `#[pin]` as a marker for +//! [structurally pinned fields]. After doing this, you can then create an in-place constructor via +//! [`pin_init!`]. The syntax is almost the same as normal `struct` initializers. The difference is +//! that you need to write `<-` instead of `:` for fields that you want to initialize in-place. +//! +//! ```rust +//! # #![allow(clippy::disallowed_names, clippy::new_ret_no_self)] +//! use kernel::{prelude::*, sync::Mutex, new_mutex}; +//! # use core::pin::Pin; +//! #[pin_data] +//! struct Foo { +//! #[pin] +//! a: Mutex, +//! b: u32, +//! } +//! +//! let foo = pin_init!(Foo { +//! a <- new_mutex!(42, "Foo::a"), +//! b: 24, +//! }); +//! ``` +//! +//! `foo` now is of the type [`impl PinInit`]. We can now use any smart pointer that we like +//! (or just the stack) to actually initialize a `Foo`: +//! +//! ```rust +//! # #![allow(clippy::disallowed_names, clippy::new_ret_no_self)] +//! # use kernel::{prelude::*, sync::Mutex, new_mutex}; +//! # use core::pin::Pin; +//! # #[pin_data] +//! # struct Foo { +//! # #[pin] +//! # a: Mutex, +//! # b: u32, +//! # } +//! # let foo = pin_init!(Foo { +//! # a <- new_mutex!(42, "Foo::a"), +//! # b: 24, +//! # }); +//! let foo: Result>> = Box::pin_init(foo); +//! ``` +//! +//! For more information see the [`pin_init!`] macro. +//! +//! ## Using a custom function/macro that returns an initializer +//! +//! Many types from the kernel supply a function/macro that returns an initializer, because the +//! above method only works for types where you can access the fields. +//! +//! ```rust +//! # use kernel::{new_mutex, sync::{Arc, Mutex}}; +//! let mtx: Result>> = Arc::pin_init(new_mutex!(42, "example::mtx")); +//! ``` +//! +//! To declare an init macro/function you just return an [`impl PinInit`]: +//! +//! ```rust +//! # #![allow(clippy::disallowed_names, clippy::new_ret_no_self)] +//! # use kernel::{sync::Mutex, prelude::*, new_mutex, init::PinInit, try_pin_init}; +//! #[pin_data] +//! struct DriverData { +//! #[pin] +//! status: Mutex, +//! buffer: Box<[u8; 1_000_000]>, +//! } +//! +//! impl DriverData { +//! fn new() -> impl PinInit { +//! try_pin_init!(Self { +//! status <- new_mutex!(0, "DriverData::status"), +//! buffer: Box::init(kernel::init::zeroed())?, +//! }) +//! } +//! } +//! ``` +//! //! [`sync`]: kernel::sync //! [pinning]: https://doc.rust-lang.org/std/pin/index.html //! [structurally pinned fields]: @@ -33,12 +115,729 @@ //! [`Opaque`]: kernel::types::Opaque //! [`pin_data`]: ::macros::pin_data //! [`UniqueArc`]: kernel::sync::UniqueArc -//! [`Box`]: alloc::boxed::Box -use core::{convert::Infallible, marker::PhantomData, mem::MaybeUninit}; +use alloc::boxed::Box; +use core::{cell::Cell, convert::Infallible, marker::PhantomData, mem::MaybeUninit, ptr}; #[doc(hidden)] pub mod __internal; +#[doc(hidden)] +pub mod macros; + +/// Construct an in-place, pinned initializer for `struct`s. +/// +/// This macro defaults the error to [`Infallible`]. If you need [`Error`], then use +/// [`try_pin_init!`]. +/// +/// The syntax is almost identical to that of a normal `struct` initializer: +/// +/// ```rust +/// # #![allow(clippy::disallowed_names, clippy::new_ret_no_self)] +/// # use kernel::{init, pin_init, macros::pin_data, init::*}; +/// # use core::pin::Pin; +/// #[pin_data] +/// struct Foo { +/// a: usize, +/// b: Bar, +/// } +/// +/// #[pin_data] +/// struct Bar { +/// x: u32, +/// } +/// +/// # fn demo() -> impl PinInit { +/// let a = 42; +/// +/// let initializer = pin_init!(Foo { +/// a, +/// b: Bar { +/// x: 64, +/// }, +/// }); +/// # initializer } +/// # Box::pin_init(demo()).unwrap(); +/// ``` +/// +/// Arbitrary Rust expressions can be used to set the value of a variable. +/// +/// The fields are initialized in the order that they appear in the initializer. So it is possible +/// to read already initialized fields using raw pointers. +/// +/// IMPORTANT: You are not allowed to create references to fields of the struct inside of the +/// initializer. +/// +/// # Init-functions +/// +/// When working with this API it is often desired to let others construct your types without +/// giving access to all fields. This is where you would normally write a plain function `new` +/// that would return a new instance of your type. With this API that is also possible. +/// However, there are a few extra things to keep in mind. +/// +/// To create an initializer function, simply declare it like this: +/// +/// ```rust +/// # #![allow(clippy::disallowed_names, clippy::new_ret_no_self)] +/// # use kernel::{init, pin_init, prelude::*, init::*}; +/// # use core::pin::Pin; +/// # #[pin_data] +/// # struct Foo { +/// # a: usize, +/// # b: Bar, +/// # } +/// # #[pin_data] +/// # struct Bar { +/// # x: u32, +/// # } +/// impl Foo { +/// fn new() -> impl PinInit { +/// pin_init!(Self { +/// a: 42, +/// b: Bar { +/// x: 64, +/// }, +/// }) +/// } +/// } +/// ``` +/// +/// Users of `Foo` can now create it like this: +/// +/// ```rust +/// # #![allow(clippy::disallowed_names, clippy::new_ret_no_self)] +/// # use kernel::{init, pin_init, macros::pin_data, init::*}; +/// # use core::pin::Pin; +/// # #[pin_data] +/// # struct Foo { +/// # a: usize, +/// # b: Bar, +/// # } +/// # #[pin_data] +/// # struct Bar { +/// # x: u32, +/// # } +/// # impl Foo { +/// # fn new() -> impl PinInit { +/// # pin_init!(Self { +/// # a: 42, +/// # b: Bar { +/// # x: 64, +/// # }, +/// # }) +/// # } +/// # } +/// let foo = Box::pin_init(Foo::new()); +/// ``` +/// +/// They can also easily embed it into their own `struct`s: +/// +/// ```rust +/// # #![allow(clippy::disallowed_names, clippy::new_ret_no_self)] +/// # use kernel::{init, pin_init, macros::pin_data, init::*}; +/// # use core::pin::Pin; +/// # #[pin_data] +/// # struct Foo { +/// # a: usize, +/// # b: Bar, +/// # } +/// # #[pin_data] +/// # struct Bar { +/// # x: u32, +/// # } +/// # impl Foo { +/// # fn new() -> impl PinInit { +/// # pin_init!(Self { +/// # a: 42, +/// # b: Bar { +/// # x: 64, +/// # }, +/// # }) +/// # } +/// # } +/// #[pin_data] +/// struct FooContainer { +/// #[pin] +/// foo1: Foo, +/// #[pin] +/// foo2: Foo, +/// other: u32, +/// } +/// +/// impl FooContainer { +/// fn new(other: u32) -> impl PinInit { +/// pin_init!(Self { +/// foo1 <- Foo::new(), +/// foo2 <- Foo::new(), +/// other, +/// }) +/// } +/// } +/// ``` +/// +/// Here we see that when using `pin_init!` with `PinInit`, one needs to write `<-` instead of `:`. +/// This signifies that the given field is initialized in-place. As with `struct` initializers, just +/// writing the field (in this case `other`) without `:` or `<-` means `other: other,`. +/// +/// # Syntax +/// +/// As already mentioned in the examples above, inside of `pin_init!` a `struct` initializer with +/// the following modifications is expected: +/// - Fields that you want to initialize in-place have to use `<-` instead of `:`. +/// - In front of the initializer you can write `&this in` to have access to a [`NonNull`] +/// pointer named `this` inside of the initializer. +/// +/// For instance: +/// +/// ```rust +/// # use kernel::pin_init; +/// # use macros::pin_data; +/// # use core::{ptr::addr_of_mut, marker::PhantomPinned}; +/// #[pin_data] +/// struct Buf { +/// // `ptr` points into `buf`. +/// ptr: *mut u8, +/// buf: [u8; 64], +/// #[pin] +/// pin: PhantomPinned, +/// } +/// pin_init!(&this in Buf { +/// buf: [0; 64], +/// ptr: unsafe { addr_of_mut!((*this.as_ptr()).buf).cast() }, +/// pin: PhantomPinned, +/// }); +/// ``` +/// +/// [`try_pin_init!`]: kernel::try_pin_init +/// [`NonNull`]: core::ptr::NonNull +/// [`Error`]: kernel::error::Error +// For a detailed example of how this macro works, see the module documentation of the hidden +// module `__internal` inside of `init/__internal.rs`. +#[macro_export] +macro_rules! pin_init { + ($(&$this:ident in)? $t:ident $(::<$($generics:ty),* $(,)?>)? { + $($fields:tt)* + }) => { + $crate::try_pin_init!( + @this($($this)?), + @typ($t $(::<$($generics),*>)?), + @fields($($fields)*), + @error(::core::convert::Infallible), + ) + }; +} + +/// Construct an in-place, fallible pinned initializer for `struct`s. +/// +/// If the initialization can complete without error (or [`Infallible`]), then use [`pin_init!`]. +/// +/// You can use the `?` operator or use `return Err(err)` inside the initializer to stop +/// initialization and return the error. +/// +/// IMPORTANT: if you have `unsafe` code inside of the initializer you have to ensure that when +/// initialization fails, the memory can be safely deallocated without any further modifications. +/// +/// This macro defaults the error to [`Error`]. +/// +/// The syntax is identical to [`pin_init!`] with the following exception: you can append `? $type` +/// after the `struct` initializer to specify the error type you want to use. +/// +/// # Examples +/// +/// ```rust +/// # #![feature(new_uninit)] +/// use kernel::{init::{self, PinInit}, error::Error}; +/// #[pin_data] +/// struct BigBuf { +/// big: Box<[u8; 1024 * 1024 * 1024]>, +/// small: [u8; 1024 * 1024], +/// ptr: *mut u8, +/// } +/// +/// impl BigBuf { +/// fn new() -> impl PinInit { +/// try_pin_init!(Self { +/// big: Box::init(init::zeroed())?, +/// small: [0; 1024 * 1024], +/// ptr: core::ptr::null_mut(), +/// }? Error) +/// } +/// } +/// ``` +/// +/// [`Error`]: kernel::error::Error +// For a detailed example of how this macro works, see the module documentation of the hidden +// module `__internal` inside of `init/__internal.rs`. +#[macro_export] +macro_rules! try_pin_init { + ($(&$this:ident in)? $t:ident $(::<$($generics:ty),* $(,)?>)? { + $($fields:tt)* + }) => { + $crate::try_pin_init!( + @this($($this)?), + @typ($t $(::<$($generics),*>)? ), + @fields($($fields)*), + @error($crate::error::Error), + ) + }; + ($(&$this:ident in)? $t:ident $(::<$($generics:ty),* $(,)?>)? { + $($fields:tt)* + }? $err:ty) => { + $crate::try_pin_init!( + @this($($this)?), + @typ($t $(::<$($generics),*>)? ), + @fields($($fields)*), + @error($err), + ) + }; + ( + @this($($this:ident)?), + @typ($t:ident $(::<$($generics:ty),*>)?), + @fields($($fields:tt)*), + @error($err:ty), + ) => {{ + // We do not want to allow arbitrary returns, so we declare this type as the `Ok` return + // type and shadow it later when we insert the arbitrary user code. That way there will be + // no possibility of returning without `unsafe`. + struct __InitOk; + // Get the pin data from the supplied type. + let data = unsafe { + use $crate::init::__internal::HasPinData; + $t$(::<$($generics),*>)?::__pin_data() + }; + // Ensure that `data` really is of type `PinData` and help with type inference: + let init = $crate::init::__internal::PinData::make_closure::<_, __InitOk, $err>( + data, + move |slot| { + { + // Shadow the structure so it cannot be used to return early. + struct __InitOk; + // Create the `this` so it can be referenced by the user inside of the + // expressions creating the individual fields. + $(let $this = unsafe { ::core::ptr::NonNull::new_unchecked(slot) };)? + // Initialize every field. + $crate::try_pin_init!(init_slot: + @data(data), + @slot(slot), + @munch_fields($($fields)*,), + ); + // We use unreachable code to ensure that all fields have been mentioned exactly + // once, this struct initializer will still be type-checked and complain with a + // very natural error message if a field is forgotten/mentioned more than once. + #[allow(unreachable_code, clippy::diverging_sub_expression)] + if false { + $crate::try_pin_init!(make_initializer: + @slot(slot), + @type_name($t), + @munch_fields($($fields)*,), + @acc(), + ); + } + // Forget all guards, since initialization was a success. + $crate::try_pin_init!(forget_guards: + @munch_fields($($fields)*,), + ); + } + Ok(__InitOk) + } + ); + let init = move |slot| -> ::core::result::Result<(), $err> { + init(slot).map(|__InitOk| ()) + }; + let init = unsafe { $crate::init::pin_init_from_closure::<_, $err>(init) }; + init + }}; + (init_slot: + @data($data:ident), + @slot($slot:ident), + @munch_fields($(,)?), + ) => { + // Endpoint of munching, no fields are left. + }; + (init_slot: + @data($data:ident), + @slot($slot:ident), + // In-place initialization syntax. + @munch_fields($field:ident <- $val:expr, $($rest:tt)*), + ) => { + let $field = $val; + // Call the initializer. + // + // SAFETY: `slot` is valid, because we are inside of an initializer closure, we + // return when an error/panic occurs. + // We also use the `data` to require the correct trait (`Init` or `PinInit`) for `$field`. + unsafe { $data.$field(::core::ptr::addr_of_mut!((*$slot).$field), $field)? }; + // Create the drop guard. + // + // We only give access to `&DropGuard`, so it cannot be forgotten via safe code. + // + // SAFETY: We forget the guard later when initialization has succeeded. + let $field = &unsafe { + $crate::init::__internal::DropGuard::new(::core::ptr::addr_of_mut!((*$slot).$field)) + }; + + $crate::try_pin_init!(init_slot: + @data($data), + @slot($slot), + @munch_fields($($rest)*), + ); + }; + (init_slot: + @data($data:ident), + @slot($slot:ident), + // Direct value init, this is safe for every field. + @munch_fields($field:ident $(: $val:expr)?, $($rest:tt)*), + ) => { + $(let $field = $val;)? + // Initialize the field. + // + // SAFETY: The memory at `slot` is uninitialized. + unsafe { ::core::ptr::write(::core::ptr::addr_of_mut!((*$slot).$field), $field) }; + // Create the drop guard: + // + // We only give access to `&DropGuard`, so it cannot be accidentally forgotten. + // + // SAFETY: We forget the guard later when initialization has succeeded. + let $field = &unsafe { + $crate::init::__internal::DropGuard::new(::core::ptr::addr_of_mut!((*$slot).$field)) + }; + + $crate::try_pin_init!(init_slot: + @data($data), + @slot($slot), + @munch_fields($($rest)*), + ); + }; + (make_initializer: + @slot($slot:ident), + @type_name($t:ident), + @munch_fields($(,)?), + @acc($($acc:tt)*), + ) => { + // Endpoint, nothing more to munch, create the initializer. + // Since we are in the `if false` branch, this will never get executed. We abuse `slot` to + // get the correct type inference here: + unsafe { + ::core::ptr::write($slot, $t { + $($acc)* + }); + } + }; + (make_initializer: + @slot($slot:ident), + @type_name($t:ident), + @munch_fields($field:ident <- $val:expr, $($rest:tt)*), + @acc($($acc:tt)*), + ) => { + $crate::try_pin_init!(make_initializer: + @slot($slot), + @type_name($t), + @munch_fields($($rest)*), + @acc($($acc)* $field: ::core::panic!(),), + ); + }; + (make_initializer: + @slot($slot:ident), + @type_name($t:ident), + @munch_fields($field:ident $(: $val:expr)?, $($rest:tt)*), + @acc($($acc:tt)*), + ) => { + $crate::try_pin_init!(make_initializer: + @slot($slot), + @type_name($t), + @munch_fields($($rest)*), + @acc($($acc)* $field: ::core::panic!(),), + ); + }; + (forget_guards: + @munch_fields($(,)?), + ) => { + // Munching finished. + }; + (forget_guards: + @munch_fields($field:ident <- $val:expr, $($rest:tt)*), + ) => { + unsafe { $crate::init::__internal::DropGuard::forget($field) }; + + $crate::try_pin_init!(forget_guards: + @munch_fields($($rest)*), + ); + }; + (forget_guards: + @munch_fields($field:ident $(: $val:expr)?, $($rest:tt)*), + ) => { + unsafe { $crate::init::__internal::DropGuard::forget($field) }; + + $crate::try_pin_init!(forget_guards: + @munch_fields($($rest)*), + ); + }; +} + +/// Construct an in-place initializer for `struct`s. +/// +/// This macro defaults the error to [`Infallible`]. If you need [`Error`], then use +/// [`try_init!`]. +/// +/// The syntax is identical to [`pin_init!`] and its safety caveats also apply: +/// - `unsafe` code must guarantee either full initialization or return an error and allow +/// deallocation of the memory. +/// - the fields are initialized in the order given in the initializer. +/// - no references to fields are allowed to be created inside of the initializer. +/// +/// This initializer is for initializing data in-place that might later be moved. If you want to +/// pin-initialize, use [`pin_init!`]. +/// +/// [`Error`]: kernel::error::Error +// For a detailed example of how this macro works, see the module documentation of the hidden +// module `__internal` inside of `init/__internal.rs`. +#[macro_export] +macro_rules! init { + ($(&$this:ident in)? $t:ident $(::<$($generics:ty),* $(,)?>)? { + $($fields:tt)* + }) => { + $crate::try_init!( + @this($($this)?), + @typ($t $(::<$($generics),*>)?), + @fields($($fields)*), + @error(::core::convert::Infallible), + ) + } +} + +/// Construct an in-place fallible initializer for `struct`s. +/// +/// This macro defaults the error to [`Error`]. If you need [`Infallible`], then use +/// [`init!`]. +/// +/// The syntax is identical to [`try_pin_init!`]. If you want to specify a custom error, +/// append `? $type` after the `struct` initializer. +/// The safety caveats from [`try_pin_init!`] also apply: +/// - `unsafe` code must guarantee either full initialization or return an error and allow +/// deallocation of the memory. +/// - the fields are initialized in the order given in the initializer. +/// - no references to fields are allowed to be created inside of the initializer. +/// +/// # Examples +/// +/// ```rust +/// use kernel::{init::PinInit, error::Error, InPlaceInit}; +/// struct BigBuf { +/// big: Box<[u8; 1024 * 1024 * 1024]>, +/// small: [u8; 1024 * 1024], +/// } +/// +/// impl BigBuf { +/// fn new() -> impl Init { +/// try_init!(Self { +/// big: Box::init(zeroed())?, +/// small: [0; 1024 * 1024], +/// }? Error) +/// } +/// } +/// ``` +/// +/// [`Error`]: kernel::error::Error +// For a detailed example of how this macro works, see the module documentation of the hidden +// module `__internal` inside of `init/__internal.rs`. +#[macro_export] +macro_rules! try_init { + ($(&$this:ident in)? $t:ident $(::<$($generics:ty),* $(,)?>)? { + $($fields:tt)* + }) => { + $crate::try_init!( + @this($($this)?), + @typ($t $(::<$($generics),*>)?), + @fields($($fields)*), + @error($crate::error::Error), + ) + }; + ($(&$this:ident in)? $t:ident $(::<$($generics:ty),* $(,)?>)? { + $($fields:tt)* + }? $err:ty) => { + $crate::try_init!( + @this($($this)?), + @typ($t $(::<$($generics),*>)?), + @fields($($fields)*), + @error($err), + ) + }; + ( + @this($($this:ident)?), + @typ($t:ident $(::<$($generics:ty),*>)?), + @fields($($fields:tt)*), + @error($err:ty), + ) => {{ + // We do not want to allow arbitrary returns, so we declare this type as the `Ok` return + // type and shadow it later when we insert the arbitrary user code. That way there will be + // no possibility of returning without `unsafe`. + struct __InitOk; + // Get the init data from the supplied type. + let data = unsafe { + use $crate::init::__internal::HasInitData; + $t$(::<$($generics),*>)?::__init_data() + }; + // Ensure that `data` really is of type `InitData` and help with type inference: + let init = $crate::init::__internal::InitData::make_closure::<_, __InitOk, $err>( + data, + move |slot| { + { + // Shadow the structure so it cannot be used to return early. + struct __InitOk; + // Create the `this` so it can be referenced by the user inside of the + // expressions creating the individual fields. + $(let $this = unsafe { ::core::ptr::NonNull::new_unchecked(slot) };)? + // Initialize every field. + $crate::try_init!(init_slot: + @slot(slot), + @munch_fields($($fields)*,), + ); + // We use unreachable code to ensure that all fields have been mentioned exactly + // once, this struct initializer will still be type-checked and complain with a + // very natural error message if a field is forgotten/mentioned more than once. + #[allow(unreachable_code, clippy::diverging_sub_expression)] + if false { + $crate::try_init!(make_initializer: + @slot(slot), + @type_name($t), + @munch_fields($($fields)*,), + @acc(), + ); + } + // Forget all guards, since initialization was a success. + $crate::try_init!(forget_guards: + @munch_fields($($fields)*,), + ); + } + Ok(__InitOk) + } + ); + let init = move |slot| -> ::core::result::Result<(), $err> { + init(slot).map(|__InitOk| ()) + }; + let init = unsafe { $crate::init::init_from_closure::<_, $err>(init) }; + init + }}; + (init_slot: + @slot($slot:ident), + @munch_fields( $(,)?), + ) => { + // Endpoint of munching, no fields are left. + }; + (init_slot: + @slot($slot:ident), + @munch_fields($field:ident <- $val:expr, $($rest:tt)*), + ) => { + let $field = $val; + // Call the initializer. + // + // SAFETY: `slot` is valid, because we are inside of an initializer closure, we + // return when an error/panic occurs. + unsafe { + $crate::init::Init::__init($field, ::core::ptr::addr_of_mut!((*$slot).$field))?; + } + // Create the drop guard. + // + // We only give access to `&DropGuard`, so it cannot be accidentally forgotten. + // + // SAFETY: We forget the guard later when initialization has succeeded. + let $field = &unsafe { + $crate::init::__internal::DropGuard::new(::core::ptr::addr_of_mut!((*$slot).$field)) + }; + + $crate::try_init!(init_slot: + @slot($slot), + @munch_fields($($rest)*), + ); + }; + (init_slot: + @slot($slot:ident), + // Direct value init. + @munch_fields($field:ident $(: $val:expr)?, $($rest:tt)*), + ) => { + $(let $field = $val;)? + // Call the initializer. + // + // SAFETY: The memory at `slot` is uninitialized. + unsafe { ::core::ptr::write(::core::ptr::addr_of_mut!((*$slot).$field), $field) }; + // Create the drop guard. + // + // We only give access to `&DropGuard`, so it cannot be accidentally forgotten. + // + // SAFETY: We forget the guard later when initialization has succeeded. + let $field = &unsafe { + $crate::init::__internal::DropGuard::new(::core::ptr::addr_of_mut!((*$slot).$field)) + }; + + $crate::try_init!(init_slot: + @slot($slot), + @munch_fields($($rest)*), + ); + }; + (make_initializer: + @slot($slot:ident), + @type_name($t:ident), + @munch_fields( $(,)?), + @acc($($acc:tt)*), + ) => { + // Endpoint, nothing more to munch, create the initializer. + // Since we are in the `if false` branch, this will never get executed. We abuse `slot` to + // get the correct type inference here: + unsafe { + ::core::ptr::write($slot, $t { + $($acc)* + }); + } + }; + (make_initializer: + @slot($slot:ident), + @type_name($t:ident), + @munch_fields($field:ident <- $val:expr, $($rest:tt)*), + @acc($($acc:tt)*), + ) => { + $crate::try_init!(make_initializer: + @slot($slot), + @type_name($t), + @munch_fields($($rest)*), + @acc($($acc)*$field: ::core::panic!(),), + ); + }; + (make_initializer: + @slot($slot:ident), + @type_name($t:ident), + @munch_fields($field:ident $(: $val:expr)?, $($rest:tt)*), + @acc($($acc:tt)*), + ) => { + $crate::try_init!(make_initializer: + @slot($slot), + @type_name($t), + @munch_fields($($rest)*), + @acc($($acc)*$field: ::core::panic!(),), + ); + }; + (forget_guards: + @munch_fields($(,)?), + ) => { + // Munching finished. + }; + (forget_guards: + @munch_fields($field:ident <- $val:expr, $($rest:tt)*), + ) => { + unsafe { $crate::init::__internal::DropGuard::forget($field) }; + + $crate::try_init!(forget_guards: + @munch_fields($($rest)*), + ); + }; + (forget_guards: + @munch_fields($field:ident $(: $val:expr)?, $($rest:tt)*), + ) => { + unsafe { $crate::init::__internal::DropGuard::forget($field) }; + + $crate::try_init!(forget_guards: + @munch_fields($($rest)*), + ); + }; +} /// A pin-initializer for the type `T`. /// @@ -63,7 +862,6 @@ pub mod __internal; /// [`Arc`]: crate::sync::Arc /// [`Arc::pin_init`]: crate::sync::Arc::pin_init /// [`UniqueArc`]: kernel::sync::UniqueArc -/// [`Box`]: alloc::boxed::Box #[must_use = "An initializer must be used in order to create its value."] pub unsafe trait PinInit: Sized { /// Initializes `slot`. @@ -106,7 +904,6 @@ pub unsafe trait PinInit: Sized { /// /// [`Arc`]: crate::sync::Arc /// [`UniqueArc`]: kernel::sync::UniqueArc -/// [`Box`]: alloc::boxed::Box #[must_use = "An initializer must be used in order to create its value."] pub unsafe trait Init: Sized { /// Initializes `slot`. diff --git a/rust/kernel/init/__internal.rs b/rust/kernel/init/__internal.rs index 08cbb5333438..a3389a684296 100644 --- a/rust/kernel/init/__internal.rs +++ b/rust/kernel/init/__internal.rs @@ -31,3 +31,133 @@ where (self.0)(slot) } } + +/// This trait is only implemented via the `#[pin_data]` proc-macro. It is used to facilitate +/// the pin projections within the initializers. +/// +/// # Safety +/// +/// Only the `init` module is allowed to use this trait. +pub unsafe trait HasPinData { + type PinData: PinData; + + unsafe fn __pin_data() -> Self::PinData; +} + +/// Marker trait for pinning data of structs. +/// +/// # Safety +/// +/// Only the `init` module is allowed to use this trait. +pub unsafe trait PinData: Copy { + type Datee: ?Sized + HasPinData; + + /// Type inference helper function. + fn make_closure(self, f: F) -> F + where + F: FnOnce(*mut Self::Datee) -> Result, + { + f + } +} + +/// This trait is automatically implemented for every type. It aims to provide the same type +/// inference help as `HasPinData`. +/// +/// # Safety +/// +/// Only the `init` module is allowed to use this trait. +pub unsafe trait HasInitData { + type InitData: InitData; + + unsafe fn __init_data() -> Self::InitData; +} + +/// Same function as `PinData`, but for arbitrary data. +/// +/// # Safety +/// +/// Only the `init` module is allowed to use this trait. +pub unsafe trait InitData: Copy { + type Datee: ?Sized + HasInitData; + + /// Type inference helper function. + fn make_closure(self, f: F) -> F + where + F: FnOnce(*mut Self::Datee) -> Result, + { + f + } +} + +pub struct AllData(PhantomData) -> Box>); + +impl Clone for AllData { + fn clone(&self) -> Self { + *self + } +} + +impl Copy for AllData {} + +unsafe impl InitData for AllData { + type Datee = T; +} + +unsafe impl HasInitData for T { + type InitData = AllData; + + unsafe fn __init_data() -> Self::InitData { + AllData(PhantomData) + } +} + +/// When a value of this type is dropped, it drops a `T`. +/// +/// Can be forgotten to prevent the drop. +pub struct DropGuard { + ptr: *mut T, + do_drop: Cell, +} + +impl DropGuard { + /// Creates a new [`DropGuard`]. It will [`ptr::drop_in_place`] `ptr` when it gets dropped. + /// + /// # Safety + /// + /// `ptr` must be a valid pointer. + /// + /// It is the callers responsibility that `self` will only get dropped if the pointee of `ptr`: + /// - has not been dropped, + /// - is not accessible by any other means, + /// - will not be dropped by any other means. + #[inline] + pub unsafe fn new(ptr: *mut T) -> Self { + Self { + ptr, + do_drop: Cell::new(true), + } + } + + /// Prevents this guard from dropping the supplied pointer. + /// + /// # Safety + /// + /// This function is unsafe in order to prevent safe code from forgetting this guard. It should + /// only be called by the macros in this module. + #[inline] + pub unsafe fn forget(&self) { + self.do_drop.set(false); + } +} + +impl Drop for DropGuard { + #[inline] + fn drop(&mut self) { + if self.do_drop.get() { + // SAFETY: A `DropGuard` can only be constructed using the unsafe `new` function + // ensuring that this operation is safe. + unsafe { ptr::drop_in_place(self.ptr) } + } + } +} diff --git a/rust/kernel/init/macros.rs b/rust/kernel/init/macros.rs new file mode 100644 index 000000000000..9ef02f5411a6 --- /dev/null +++ b/rust/kernel/init/macros.rs @@ -0,0 +1,707 @@ +// SPDX-License-Identifier: Apache-2.0 OR MIT + +//! This module provides the macros that actually implement the proc-macros `pin_data` and +//! `pinned_drop`. +//! +//! These macros should never be called directly, since they expect their input to be +//! in a certain format which is internal. Use the proc-macros instead. +//! +//! This architecture has been chosen because the kernel does not yet have access to `syn` which +//! would make matters a lot easier for implementing these as proc-macros. +//! +//! # Macro expansion example +//! +//! This section is intended for readers trying to understand the macros in this module and the +//! `pin_init!` macros from `init.rs`. +//! +//! We will look at the following example: +//! +//! ```rust +//! # use kernel::init::*; +//! #[pin_data] +//! #[repr(C)] +//! struct Bar { +//! #[pin] +//! t: T, +//! pub x: usize, +//! } +//! +//! impl Bar { +//! fn new(t: T) -> impl PinInit { +//! pin_init!(Self { t, x: 0 }) +//! } +//! } +//! ``` +//! +//! This example includes the most common and important features of the pin-init API. +//! +//! Below you can find individual section about the different macro invocations. Here are some +//! general things we need to take into account when designing macros: +//! - use global paths, similarly to file paths, these start with the separator: `::core::panic!()` +//! this ensures that the correct item is used, since users could define their own `mod core {}` +//! and then their own `panic!` inside to execute arbitrary code inside of our macro. +//! - macro `unsafe` hygiene: we need to ensure that we do not expand arbitrary, user-supplied +//! expressions inside of an `unsafe` block in the macro, because this would allow users to do +//! `unsafe` operations without an associated `unsafe` block. +//! +//! ## `#[pin_data]` on `Bar` +//! +//! This macro is used to specify which fields are structurally pinned and which fields are not. It +//! is placed on the struct definition and allows `#[pin]` to be placed on the fields. +//! +//! Here is the definition of `Bar` from our example: +//! +//! ```rust +//! # use kernel::init::*; +//! #[pin_data] +//! #[repr(C)] +//! struct Bar { +//! t: T, +//! pub x: usize, +//! } +//! ``` +//! +//! This expands to the following code: +//! +//! ```rust +//! // Firstly the normal definition of the struct, attributes are preserved: +//! #[repr(C)] +//! struct Bar { +//! t: T, +//! pub x: usize, +//! } +//! // Then an anonymous constant is defined, this is because we do not want any code to access the +//! // types that we define inside: +//! const _: () = { +//! // We define the pin-data carrying struct, it is a ZST and needs to have the same generics, +//! // since we need to implement access functions for each field and thus need to know its +//! // type. +//! struct __ThePinData { +//! __phantom: ::core::marker::PhantomData) -> Bar>, +//! } +//! // We implement `Copy` for the pin-data struct, since all functions it defines will take +//! // `self` by value. +//! impl ::core::clone::Clone for __ThePinData { +//! fn clone(&self) -> Self { +//! *self +//! } +//! } +//! impl ::core::marker::Copy for __ThePinData {} +//! // For every field of `Bar`, the pin-data struct will define a function with the same name +//! // and accessor (`pub` or `pub(crate)` etc.). This function will take a pointer to the +//! // field (`slot`) and a `PinInit` or `Init` depending on the projection kind of the field +//! // (if pinning is structural for the field, then `PinInit` otherwise `Init`). +//! #[allow(dead_code)] +//! impl __ThePinData { +//! unsafe fn t( +//! self, +//! slot: *mut T, +//! init: impl ::kernel::init::Init, +//! ) -> ::core::result::Result<(), E> { +//! unsafe { ::kernel::init::Init::__init(init, slot) } +//! } +//! pub unsafe fn x( +//! self, +//! slot: *mut usize, +//! init: impl ::kernel::init::Init, +//! ) -> ::core::result::Result<(), E> { +//! unsafe { ::kernel::init::Init::__init(init, slot) } +//! } +//! } +//! // Implement the internal `HasPinData` trait that associates `Bar` with the pin-data struct +//! // that we constructed beforehand. +//! unsafe impl ::kernel::init::__internal::HasPinData for Bar { +//! type PinData = __ThePinData; +//! unsafe fn __pin_data() -> Self::PinData { +//! __ThePinData { +//! __phantom: ::core::marker::PhantomData, +//! } +//! } +//! } +//! // Implement the internal `PinData` trait that marks the pin-data struct as a pin-data +//! // struct. This is important to ensure that no user can implement a rouge `__pin_data` +//! // function without using `unsafe`. +//! unsafe impl ::kernel::init::__internal::PinData for __ThePinData { +//! type Datee = Bar; +//! } +//! // Now we only want to implement `Unpin` for `Bar` when every structurally pinned field is +//! // `Unpin`. In other words, whether `Bar` is `Unpin` only depends on structurally pinned +//! // fields (those marked with `#[pin]`). These fields will be listed in this struct, in our +//! // case no such fields exist, hence this is almost empty. The two phantomdata fields exist +//! // for two reasons: +//! // - `__phantom`: every generic must be used, since we cannot really know which generics +//! // are used, we declere all and then use everything here once. +//! // - `__phantom_pin`: uses the `'__pin` lifetime and ensures that this struct is invariant +//! // over it. The lifetime is needed to work around the limitation that trait bounds must +//! // not be trivial, e.g. the user has a `#[pin] PhantomPinned` field -- this is +//! // unconditionally `!Unpin` and results in an error. The lifetime tricks the compiler +//! // into accepting these bounds regardless. +//! #[allow(dead_code)] +//! struct __Unpin<'__pin, T> { +//! __phantom_pin: ::core::marker::PhantomData &'__pin ()>, +//! __phantom: ::core::marker::PhantomData) -> Bar>, +//! } +//! #[doc(hidden)] +//! impl<'__pin, T> +//! ::core::marker::Unpin for Bar where __Unpin<'__pin, T>: ::core::marker::Unpin {} +//! // Now we need to ensure that `Bar` does not implement `Drop`, since that would give users +//! // access to `&mut self` inside of `drop` even if the struct was pinned. This could lead to +//! // UB with only safe code, so we disallow this by giving a trait implementation error using +//! // a direct impl and a blanket implementation. +//! trait MustNotImplDrop {} +//! // Normally `Drop` bounds do not have the correct semantics, but for this purpose they do +//! // (normally people want to know if a type has any kind of drop glue at all, here we want +//! // to know if it has any kind of custom drop glue, which is exactly what this bound does). +//! #[allow(drop_bounds)] +//! impl MustNotImplDrop for T {} +//! impl MustNotImplDrop for Bar {} +//! }; +//! ``` +//! +//! ## `pin_init!` in `impl Bar` +//! +//! This macro creates an pin-initializer for the given struct. It requires that the struct is +//! annotated by `#[pin_data]`. +//! +//! Here is the impl on `Bar` defining the new function: +//! +//! ```rust +//! impl Bar { +//! fn new(t: T) -> impl PinInit { +//! pin_init!(Self { t, x: 0 }) +//! } +//! } +//! ``` +//! +//! This expands to the following code: +//! +//! ```rust +//! impl Bar { +//! fn new(t: T) -> impl PinInit { +//! { +//! // We do not want to allow arbitrary returns, so we declare this type as the `Ok` +//! // return type and shadow it later when we insert the arbitrary user code. That way +//! // there will be no possibility of returning without `unsafe`. +//! struct __InitOk; +//! // Get the pin-data type from the initialized type. +//! // - the function is unsafe, hence the unsafe block +//! // - we `use` the `HasPinData` trait in the block, it is only available in that +//! // scope. +//! let data = unsafe { +//! use ::kernel::init::__internal::HasPinData; +//! Self::__pin_data() +//! }; +//! // Use `data` to help with type inference, the closure supplied will have the type +//! // `FnOnce(*mut Self) -> Result<__InitOk, Infallible>`. +//! let init = ::kernel::init::__internal::PinData::make_closure::< +//! _, +//! __InitOk, +//! ::core::convert::Infallible, +//! >(data, move |slot| { +//! { +//! // Shadow the structure so it cannot be used to return early. If a user +//! // tries to write `return Ok(__InitOk)`, then they get a type error, since +//! // that will refer to this struct instead of the one defined above. +//! struct __InitOk; +//! // This is the expansion of `t,`, which is syntactic sugar for `t: t,`. +//! unsafe { ::core::ptr::write(&raw mut (*slot).t, t) }; +//! // Since initialization could fail later (not in this case, since the error +//! // type is `Infallible`) we will need to drop this field if it fails. This +//! // `DropGuard` will drop the field when it gets dropped and has not yet +//! // been forgotten. We make a reference to it, so users cannot `mem::forget` +//! // it from the initializer, since the name is the same as the field. +//! let t = &unsafe { +//! ::kernel::init::__internal::DropGuard::new(&raw mut (*slot).t) +//! }; +//! // Expansion of `x: 0,`: +//! // Since this can be an arbitrary expression we cannot place it inside of +//! // the `unsafe` block, so we bind it here. +//! let x = 0; +//! unsafe { ::core::ptr::write(&raw mut (*slot).x, x) }; +//! let x = &unsafe { +//! ::kernel::init::__internal::DropGuard::new(&raw mut (*slot).x) +//! }; +//! +//! // Here we use the type checker to ensuer that every field has been +//! // initialized exactly once, since this is `if false` it will never get +//! // executed, but still type-checked. +//! // Additionally we abuse `slot` to automatically infer the correct type for +//! // the struct. This is also another check that every field is accessible +//! // from this scope. +//! #[allow(unreachable_code, clippy::diverging_sub_expression)] +//! if false { +//! unsafe { +//! ::core::ptr::write( +//! slot, +//! Self { +//! // We only care about typecheck finding every field here, +//! // the expression does not matter, just conjure one using +//! // `panic!()`: +//! t: ::core::panic!(), +//! x: ::core::panic!(), +//! }, +//! ); +//! }; +//! } +//! // Since initialization has successfully completed, we can now forget the +//! // guards. +//! unsafe { ::kernel::init::__internal::DropGuard::forget(t) }; +//! unsafe { ::kernel::init::__internal::DropGuard::forget(x) }; +//! } +//! // We leave the scope above and gain access to the previously shadowed +//! // `__InitOk` that we need to return. +//! Ok(__InitOk) +//! }); +//! // Change the return type of the closure. +//! let init = move |slot| -> ::core::result::Result<(), ::core::convert::Infallible> { +//! init(slot).map(|__InitOk| ()) +//! }; +//! // Construct the initializer. +//! let init = unsafe { +//! ::kernel::init::pin_init_from_closure::<_, ::core::convert::Infallible>(init) +//! }; +//! init +//! } +//! } +//! } +//! ``` + +/// This macro first parses the struct definition such that it separates pinned and not pinned +/// fields. Afterwards it declares the struct and implement the `PinData` trait safely. +#[doc(hidden)] +#[macro_export] +macro_rules! __pin_data { + // Proc-macro entry point, this is supplied by the proc-macro pre-parsing. + (parse_input: + @args($($pinned_drop:ident)?), + @sig( + $(#[$($struct_attr:tt)*])* + $vis:vis struct $name:ident + $(where $($whr:tt)*)? + ), + @impl_generics($($impl_generics:tt)*), + @ty_generics($($ty_generics:tt)*), + @body({ $($fields:tt)* }), + ) => { + // We now use token munching to iterate through all of the fields. While doing this we + // identify fields marked with `#[pin]`, these fields are the 'pinned fields'. The user + // wants these to be structurally pinned. The rest of the fields are the + // 'not pinned fields'. Additionally we collect all fields, since we need them in the right + // order to declare the struct. + // + // In this call we also put some explaining comments for the parameters. + $crate::__pin_data!(find_pinned_fields: + // Attributes on the struct itself, these will just be propagated to be put onto the + // struct definition. + @struct_attrs($(#[$($struct_attr)*])*), + // The visibility of the struct. + @vis($vis), + // The name of the struct. + @name($name), + // The 'impl generics', the generics that will need to be specified on the struct inside + // of an `impl<$ty_generics>` block. + @impl_generics($($impl_generics)*), + // The 'ty generics', the generics that will need to be specified on the impl blocks. + @ty_generics($($ty_generics)*), + // The where clause of any impl block and the declaration. + @where($($($whr)*)?), + // The remaining fields tokens that need to be processed. + // We add a `,` at the end to ensure correct parsing. + @fields_munch($($fields)* ,), + // The pinned fields. + @pinned(), + // The not pinned fields. + @not_pinned(), + // All fields. + @fields(), + // The accumulator containing all attributes already parsed. + @accum(), + // Contains `yes` or `` to indicate if `#[pin]` was found on the current field. + @is_pinned(), + // The proc-macro argument, this should be `PinnedDrop` or ``. + @pinned_drop($($pinned_drop)?), + ); + }; + (find_pinned_fields: + @struct_attrs($($struct_attrs:tt)*), + @vis($vis:vis), + @name($name:ident), + @impl_generics($($impl_generics:tt)*), + @ty_generics($($ty_generics:tt)*), + @where($($whr:tt)*), + // We found a PhantomPinned field, this should generally be pinned! + @fields_munch($field:ident : $($($(::)?core::)?marker::)?PhantomPinned, $($rest:tt)*), + @pinned($($pinned:tt)*), + @not_pinned($($not_pinned:tt)*), + @fields($($fields:tt)*), + @accum($($accum:tt)*), + // This field is not pinned. + @is_pinned(), + @pinned_drop($($pinned_drop:ident)?), + ) => { + ::core::compile_error!(concat!( + "The field `", + stringify!($field), + "` of type `PhantomPinned` only has an effect, if it has the `#[pin]` attribute.", + )); + $crate::__pin_data!(find_pinned_fields: + @struct_attrs($($struct_attrs)*), + @vis($vis), + @name($name), + @impl_generics($($impl_generics)*), + @ty_generics($($ty_generics)*), + @where($($whr)*), + @fields_munch($($rest)*), + @pinned($($pinned)* $($accum)* $field: ::core::marker::PhantomPinned,), + @not_pinned($($not_pinned)*), + @fields($($fields)* $($accum)* $field: ::core::marker::PhantomPinned,), + @accum(), + @is_pinned(), + @pinned_drop($($pinned_drop)?), + ); + }; + (find_pinned_fields: + @struct_attrs($($struct_attrs:tt)*), + @vis($vis:vis), + @name($name:ident), + @impl_generics($($impl_generics:tt)*), + @ty_generics($($ty_generics:tt)*), + @where($($whr:tt)*), + // We reached the field declaration. + @fields_munch($field:ident : $type:ty, $($rest:tt)*), + @pinned($($pinned:tt)*), + @not_pinned($($not_pinned:tt)*), + @fields($($fields:tt)*), + @accum($($accum:tt)*), + // This field is pinned. + @is_pinned(yes), + @pinned_drop($($pinned_drop:ident)?), + ) => { + $crate::__pin_data!(find_pinned_fields: + @struct_attrs($($struct_attrs)*), + @vis($vis), + @name($name), + @impl_generics($($impl_generics)*), + @ty_generics($($ty_generics)*), + @where($($whr)*), + @fields_munch($($rest)*), + @pinned($($pinned)* $($accum)* $field: $type,), + @not_pinned($($not_pinned)*), + @fields($($fields)* $($accum)* $field: $type,), + @accum(), + @is_pinned(), + @pinned_drop($($pinned_drop)?), + ); + }; + (find_pinned_fields: + @struct_attrs($($struct_attrs:tt)*), + @vis($vis:vis), + @name($name:ident), + @impl_generics($($impl_generics:tt)*), + @ty_generics($($ty_generics:tt)*), + @where($($whr:tt)*), + // We reached the field declaration. + @fields_munch($field:ident : $type:ty, $($rest:tt)*), + @pinned($($pinned:tt)*), + @not_pinned($($not_pinned:tt)*), + @fields($($fields:tt)*), + @accum($($accum:tt)*), + // This field is not pinned. + @is_pinned(), + @pinned_drop($($pinned_drop:ident)?), + ) => { + $crate::__pin_data!(find_pinned_fields: + @struct_attrs($($struct_attrs)*), + @vis($vis), + @name($name), + @impl_generics($($impl_generics)*), + @ty_generics($($ty_generics)*), + @where($($whr)*), + @fields_munch($($rest)*), + @pinned($($pinned)*), + @not_pinned($($not_pinned)* $($accum)* $field: $type,), + @fields($($fields)* $($accum)* $field: $type,), + @accum(), + @is_pinned(), + @pinned_drop($($pinned_drop)?), + ); + }; + (find_pinned_fields: + @struct_attrs($($struct_attrs:tt)*), + @vis($vis:vis), + @name($name:ident), + @impl_generics($($impl_generics:tt)*), + @ty_generics($($ty_generics:tt)*), + @where($($whr:tt)*), + // We found the `#[pin]` attr. + @fields_munch(#[pin] $($rest:tt)*), + @pinned($($pinned:tt)*), + @not_pinned($($not_pinned:tt)*), + @fields($($fields:tt)*), + @accum($($accum:tt)*), + @is_pinned($($is_pinned:ident)?), + @pinned_drop($($pinned_drop:ident)?), + ) => { + $crate::__pin_data!(find_pinned_fields: + @struct_attrs($($struct_attrs)*), + @vis($vis), + @name($name), + @impl_generics($($impl_generics)*), + @ty_generics($($ty_generics)*), + @where($($whr)*), + @fields_munch($($rest)*), + // We do not include `#[pin]` in the list of attributes, since it is not actually an + // attribute that is defined somewhere. + @pinned($($pinned)*), + @not_pinned($($not_pinned)*), + @fields($($fields)*), + @accum($($accum)*), + // Set this to `yes`. + @is_pinned(yes), + @pinned_drop($($pinned_drop)?), + ); + }; + (find_pinned_fields: + @struct_attrs($($struct_attrs:tt)*), + @vis($vis:vis), + @name($name:ident), + @impl_generics($($impl_generics:tt)*), + @ty_generics($($ty_generics:tt)*), + @where($($whr:tt)*), + // We reached the field declaration with visibility, for simplicity we only munch the + // visibility and put it into `$accum`. + @fields_munch($fvis:vis $field:ident $($rest:tt)*), + @pinned($($pinned:tt)*), + @not_pinned($($not_pinned:tt)*), + @fields($($fields:tt)*), + @accum($($accum:tt)*), + @is_pinned($($is_pinned:ident)?), + @pinned_drop($($pinned_drop:ident)?), + ) => { + $crate::__pin_data!(find_pinned_fields: + @struct_attrs($($struct_attrs)*), + @vis($vis), + @name($name), + @impl_generics($($impl_generics)*), + @ty_generics($($ty_generics)*), + @where($($whr)*), + @fields_munch($field $($rest)*), + @pinned($($pinned)*), + @not_pinned($($not_pinned)*), + @fields($($fields)*), + @accum($($accum)* $fvis), + @is_pinned($($is_pinned)?), + @pinned_drop($($pinned_drop)?), + ); + }; + (find_pinned_fields: + @struct_attrs($($struct_attrs:tt)*), + @vis($vis:vis), + @name($name:ident), + @impl_generics($($impl_generics:tt)*), + @ty_generics($($ty_generics:tt)*), + @where($($whr:tt)*), + // Some other attribute, just put it into `$accum`. + @fields_munch(#[$($attr:tt)*] $($rest:tt)*), + @pinned($($pinned:tt)*), + @not_pinned($($not_pinned:tt)*), + @fields($($fields:tt)*), + @accum($($accum:tt)*), + @is_pinned($($is_pinned:ident)?), + @pinned_drop($($pinned_drop:ident)?), + ) => { + $crate::__pin_data!(find_pinned_fields: + @struct_attrs($($struct_attrs)*), + @vis($vis), + @name($name), + @impl_generics($($impl_generics)*), + @ty_generics($($ty_generics)*), + @where($($whr)*), + @fields_munch($($rest)*), + @pinned($($pinned)*), + @not_pinned($($not_pinned)*), + @fields($($fields)*), + @accum($($accum)* #[$($attr)*]), + @is_pinned($($is_pinned)?), + @pinned_drop($($pinned_drop)?), + ); + }; + (find_pinned_fields: + @struct_attrs($($struct_attrs:tt)*), + @vis($vis:vis), + @name($name:ident), + @impl_generics($($impl_generics:tt)*), + @ty_generics($($ty_generics:tt)*), + @where($($whr:tt)*), + // We reached the end of the fields, plus an optional additional comma, since we added one + // before and the user is also allowed to put a trailing comma. + @fields_munch($(,)?), + @pinned($($pinned:tt)*), + @not_pinned($($not_pinned:tt)*), + @fields($($fields:tt)*), + @accum(), + @is_pinned(), + @pinned_drop($($pinned_drop:ident)?), + ) => { + // Declare the struct with all fields in the correct order. + $($struct_attrs)* + $vis struct $name <$($impl_generics)*> + where $($whr)* + { + $($fields)* + } + + // We put the rest into this const item, because it then will not be accessible to anything + // outside. + const _: () = { + // We declare this struct which will host all of the projection function for our type. + // it will be invariant over all generic parameters which are inherited from the + // struct. + $vis struct __ThePinData<$($impl_generics)*> + where $($whr)* + { + __phantom: ::core::marker::PhantomData< + fn($name<$($ty_generics)*>) -> $name<$($ty_generics)*> + >, + } + + impl<$($impl_generics)*> ::core::clone::Clone for __ThePinData<$($ty_generics)*> + where $($whr)* + { + fn clone(&self) -> Self { *self } + } + + impl<$($impl_generics)*> ::core::marker::Copy for __ThePinData<$($ty_generics)*> + where $($whr)* + {} + + // Make all projection functions. + $crate::__pin_data!(make_pin_data: + @pin_data(__ThePinData), + @impl_generics($($impl_generics)*), + @ty_generics($($ty_generics)*), + @where($($whr)*), + @pinned($($pinned)*), + @not_pinned($($not_pinned)*), + ); + + // SAFETY: We have added the correct projection functions above to `__ThePinData` and + // we also use the least restrictive generics possible. + unsafe impl<$($impl_generics)*> + $crate::init::__internal::HasPinData for $name<$($ty_generics)*> + where $($whr)* + { + type PinData = __ThePinData<$($ty_generics)*>; + + unsafe fn __pin_data() -> Self::PinData { + __ThePinData { __phantom: ::core::marker::PhantomData } + } + } + + unsafe impl<$($impl_generics)*> + $crate::init::__internal::PinData for __ThePinData<$($ty_generics)*> + where $($whr)* + { + type Datee = $name<$($ty_generics)*>; + } + + // This struct will be used for the unpin analysis. Since only structurally pinned + // fields are relevant whether the struct should implement `Unpin`. + #[allow(dead_code)] + struct __Unpin <'__pin, $($impl_generics)*> + where $($whr)* + { + __phantom_pin: ::core::marker::PhantomData &'__pin ()>, + __phantom: ::core::marker::PhantomData< + fn($name<$($ty_generics)*>) -> $name<$($ty_generics)*> + >, + // Only the pinned fields. + $($pinned)* + } + + #[doc(hidden)] + impl<'__pin, $($impl_generics)*> ::core::marker::Unpin for $name<$($ty_generics)*> + where + __Unpin<'__pin, $($ty_generics)*>: ::core::marker::Unpin, + $($whr)* + {} + + // We need to disallow normal `Drop` implementation, the exact behavior depends on + // whether `PinnedDrop` was specified as the parameter. + $crate::__pin_data!(drop_prevention: + @name($name), + @impl_generics($($impl_generics)*), + @ty_generics($($ty_generics)*), + @where($($whr)*), + @pinned_drop($($pinned_drop)?), + ); + }; + }; + // When no `PinnedDrop` was specified, then we have to prevent implementing drop. + (drop_prevention: + @name($name:ident), + @impl_generics($($impl_generics:tt)*), + @ty_generics($($ty_generics:tt)*), + @where($($whr:tt)*), + @pinned_drop(), + ) => { + // We prevent this by creating a trait that will be implemented for all types implementing + // `Drop`. Additionally we will implement this trait for the struct leading to a conflict, + // if it also implements `Drop` + trait MustNotImplDrop {} + #[allow(drop_bounds)] + impl MustNotImplDrop for T {} + impl<$($impl_generics)*> MustNotImplDrop for $name<$($ty_generics)*> + where $($whr)* {} + }; + // If some other parameter was specified, we emit a readable error. + (drop_prevention: + @name($name:ident), + @impl_generics($($impl_generics:tt)*), + @ty_generics($($ty_generics:tt)*), + @where($($whr:tt)*), + @pinned_drop($($rest:tt)*), + ) => { + compile_error!( + "Wrong parameters to `#[pin_data]`, expected nothing or `PinnedDrop`, got '{}'.", + stringify!($($rest)*), + ); + }; + (make_pin_data: + @pin_data($pin_data:ident), + @impl_generics($($impl_generics:tt)*), + @ty_generics($($ty_generics:tt)*), + @where($($whr:tt)*), + @pinned($($(#[$($p_attr:tt)*])* $pvis:vis $p_field:ident : $p_type:ty),* $(,)?), + @not_pinned($($(#[$($attr:tt)*])* $fvis:vis $field:ident : $type:ty),* $(,)?), + ) => { + // For every field, we create a projection function according to its projection type. If a + // field is structurally pinned, then it must be initialized via `PinInit`, if it is not + // structurally pinned, then it can be initialized via `Init`. + // + // The functions are `unsafe` to prevent accidentally calling them. + #[allow(dead_code)] + impl<$($impl_generics)*> $pin_data<$($ty_generics)*> + where $($whr)* + { + $( + $pvis unsafe fn $p_field( + self, + slot: *mut $p_type, + init: impl $crate::init::PinInit<$p_type, E>, + ) -> ::core::result::Result<(), E> { + unsafe { $crate::init::PinInit::__pinned_init(init, slot) } + } + )* + $( + $fvis unsafe fn $field( + self, + slot: *mut $type, + init: impl $crate::init::Init<$type, E>, + ) -> ::core::result::Result<(), E> { + unsafe { $crate::init::Init::__init(init, slot) } + } + )* + } + }; +} diff --git a/rust/macros/lib.rs b/rust/macros/lib.rs index 82b520f024dd..6d84f2fd0d77 100644 --- a/rust/macros/lib.rs +++ b/rust/macros/lib.rs @@ -7,6 +7,7 @@ mod quote; mod concat_idents; mod helpers; mod module; +mod pin_data; mod vtable; use proc_macro::TokenStream; @@ -168,3 +169,31 @@ pub fn vtable(attr: TokenStream, ts: TokenStream) -> TokenStream { pub fn concat_idents(ts: TokenStream) -> TokenStream { concat_idents::concat_idents(ts) } + +/// Used to specify the pinning information of the fields of a struct. +/// +/// This is somewhat similar in purpose as +/// [pin-project-lite](https://crates.io/crates/pin-project-lite). +/// Place this macro on a struct definition and then `#[pin]` in front of the attributes of each +/// field you want to structurally pin. +/// +/// This macro enables the use of the [`pin_init!`] macro. When pin-initializing a `struct`, +/// then `#[pin]` directs the type of initializer that is required. +/// +/// # Examples +/// +/// ```rust,ignore +/// #[pin_data] +/// struct DriverData { +/// #[pin] +/// queue: Mutex>, +/// buf: Box<[u8; 1024 * 1024]>, +/// } +/// ``` +/// +/// [`pin_init!`]: ../kernel/macro.pin_init.html +// ^ cannot use direct link, since `kernel` is not a dependency of `macros`. +#[proc_macro_attribute] +pub fn pin_data(inner: TokenStream, item: TokenStream) -> TokenStream { + pin_data::pin_data(inner, item) +} diff --git a/rust/macros/pin_data.rs b/rust/macros/pin_data.rs new file mode 100644 index 000000000000..954149d77181 --- /dev/null +++ b/rust/macros/pin_data.rs @@ -0,0 +1,79 @@ +// SPDX-License-Identifier: Apache-2.0 OR MIT + +use proc_macro::{Punct, Spacing, TokenStream, TokenTree}; + +pub(crate) fn pin_data(args: TokenStream, input: TokenStream) -> TokenStream { + // This proc-macro only does some pre-parsing and then delegates the actual parsing to + // `kernel::__pin_data!`. + // + // In here we only collect the generics, since parsing them in declarative macros is very + // elaborate. We also do not need to analyse their structure, we only need to collect them. + + // `impl_generics`, the declared generics with their bounds. + let mut impl_generics = vec![]; + // Only the names of the generics, without any bounds. + let mut ty_generics = vec![]; + // Tokens not related to the generics e.g. the `impl` token. + let mut rest = vec![]; + // The current level of `<`. + let mut nesting = 0; + let mut toks = input.into_iter(); + // If we are at the beginning of a generic parameter. + let mut at_start = true; + for tt in &mut toks { + match tt.clone() { + TokenTree::Punct(p) if p.as_char() == '<' => { + if nesting >= 1 { + impl_generics.push(tt); + } + nesting += 1; + } + TokenTree::Punct(p) if p.as_char() == '>' => { + if nesting == 0 { + break; + } else { + nesting -= 1; + if nesting >= 1 { + impl_generics.push(tt); + } + if nesting == 0 { + break; + } + } + } + tt => { + if nesting == 1 { + match &tt { + TokenTree::Ident(i) if i.to_string() == "const" => {} + TokenTree::Ident(_) if at_start => { + ty_generics.push(tt.clone()); + ty_generics.push(TokenTree::Punct(Punct::new(',', Spacing::Alone))); + at_start = false; + } + TokenTree::Punct(p) if p.as_char() == ',' => at_start = true, + TokenTree::Punct(p) if p.as_char() == '\'' && at_start => { + ty_generics.push(tt.clone()); + } + _ => {} + } + } + if nesting >= 1 { + impl_generics.push(tt); + } else if nesting == 0 { + rest.push(tt); + } + } + } + } + rest.extend(toks); + // This should be the body of the struct `{...}`. + let last = rest.pop(); + quote!(::kernel::__pin_data! { + parse_input: + @args(#args), + @sig(#(#rest)*), + @impl_generics(#(#impl_generics)*), + @ty_generics(#(#ty_generics)*), + @body(#last), + }) +} diff --git a/rust/macros/quote.rs b/rust/macros/quote.rs index 94a6277182ee..c8e08b3c1e4c 100644 --- a/rust/macros/quote.rs +++ b/rust/macros/quote.rs @@ -38,7 +38,6 @@ impl ToTokens for TokenStream { /// This is a similar to the /// [`quote_spanned!`](https://docs.rs/quote/latest/quote/macro.quote_spanned.html) macro from the /// `quote` crate but provides only just enough functionality needed by the current `macros` crate. -#[allow(unused_macros)] macro_rules! quote_spanned { ($span:expr => $($tt:tt)*) => { #[allow(clippy::vec_init_then_push)] @@ -137,7 +136,6 @@ macro_rules! quote_spanned { /// `macros` crate. /// /// [`Span::mixed_site()`]: https://doc.rust-lang.org/proc_macro/struct.Span.html#method.mixed_site -#[allow(unused_macros)] macro_rules! quote { ($($tt:tt)*) => { quote_spanned!(::proc_macro::Span::mixed_site() => $($tt)*) -- cgit v1.2.3 From 92c4a1e7e81cc775b2ad6bedb348098230f7ed87 Mon Sep 17 00:00:00 2001 From: Benno Lossin Date: Sat, 8 Apr 2023 12:25:56 +0000 Subject: rust: init/sync: add `InPlaceInit` trait to pin-initialize smart pointers The `InPlaceInit` trait that provides two functions, for initializing using `PinInit` and `Init`. It is implemented by `Arc`, `UniqueArc` and `Box`. Signed-off-by: Benno Lossin Reviewed-by: Alice Ryhl Reviewed-by: Gary Guo Reviewed-by: Andreas Hindborg Link: https://lore.kernel.org/r/20230408122429.1103522-9-y86-dev@protonmail.com Signed-off-by: Miguel Ojeda --- rust/kernel/init.rs | 128 +++++++++++++++++++++++++++++++++++++++++++----- rust/kernel/sync/arc.rs | 24 +++++++++ 2 files changed, 139 insertions(+), 13 deletions(-) (limited to 'rust') diff --git a/rust/kernel/init.rs b/rust/kernel/init.rs index ecef0376d726..6499cf5c9c20 100644 --- a/rust/kernel/init.rs +++ b/rust/kernel/init.rs @@ -114,10 +114,16 @@ //! [`impl Init`]: Init //! [`Opaque`]: kernel::types::Opaque //! [`pin_data`]: ::macros::pin_data -//! [`UniqueArc`]: kernel::sync::UniqueArc +use crate::{ + error::{self, Error}, + sync::UniqueArc, +}; use alloc::boxed::Box; -use core::{cell::Cell, convert::Infallible, marker::PhantomData, mem::MaybeUninit, ptr}; +use core::{ + alloc::AllocError, cell::Cell, convert::Infallible, marker::PhantomData, mem::MaybeUninit, + pin::Pin, ptr, +}; #[doc(hidden)] pub mod __internal; @@ -309,7 +315,6 @@ pub mod macros; /// /// [`try_pin_init!`]: kernel::try_pin_init /// [`NonNull`]: core::ptr::NonNull -/// [`Error`]: kernel::error::Error // For a detailed example of how this macro works, see the module documentation of the hidden // module `__internal` inside of `init/__internal.rs`. #[macro_export] @@ -363,8 +368,6 @@ macro_rules! pin_init { /// } /// } /// ``` -/// -/// [`Error`]: kernel::error::Error // For a detailed example of how this macro works, see the module documentation of the hidden // module `__internal` inside of `init/__internal.rs`. #[macro_export] @@ -586,8 +589,6 @@ macro_rules! try_pin_init { /// /// This initializer is for initializing data in-place that might later be moved. If you want to /// pin-initialize, use [`pin_init!`]. -/// -/// [`Error`]: kernel::error::Error // For a detailed example of how this macro works, see the module documentation of the hidden // module `__internal` inside of `init/__internal.rs`. #[macro_export] @@ -635,8 +636,6 @@ macro_rules! init { /// } /// } /// ``` -/// -/// [`Error`]: kernel::error::Error // For a detailed example of how this macro works, see the module documentation of the hidden // module `__internal` inside of `init/__internal.rs`. #[macro_export] @@ -842,7 +841,8 @@ macro_rules! try_init { /// A pin-initializer for the type `T`. /// /// To use this initializer, you will need a suitable memory location that can hold a `T`. This can -/// be [`Box`], [`Arc`], [`UniqueArc`]. +/// be [`Box`], [`Arc`], [`UniqueArc`]. Use the [`InPlaceInit::pin_init`] function of a +/// smart pointer like [`Arc`] on this. /// /// Also see the [module description](self). /// @@ -861,7 +861,6 @@ macro_rules! try_init { /// /// [`Arc`]: crate::sync::Arc /// [`Arc::pin_init`]: crate::sync::Arc::pin_init -/// [`UniqueArc`]: kernel::sync::UniqueArc #[must_use = "An initializer must be used in order to create its value."] pub unsafe trait PinInit: Sized { /// Initializes `slot`. @@ -878,7 +877,8 @@ pub unsafe trait PinInit: Sized { /// An initializer for `T`. /// /// To use this initializer, you will need a suitable memory location that can hold a `T`. This can -/// be [`Box`], [`Arc`], [`UniqueArc`]. Because [`PinInit`] is a super trait, you can +/// be [`Box`], [`Arc`], [`UniqueArc`]. Use the [`InPlaceInit::init`] function of a smart +/// pointer like [`Arc`] on this. Because [`PinInit`] is a super trait, you can /// use every function that takes it as well. /// /// Also see the [module description](self). @@ -903,7 +903,6 @@ pub unsafe trait PinInit: Sized { /// move the pointee after initialization. /// /// [`Arc`]: crate::sync::Arc -/// [`UniqueArc`]: kernel::sync::UniqueArc #[must_use = "An initializer must be used in order to create its value."] pub unsafe trait Init: Sized { /// Initializes `slot`. @@ -982,3 +981,106 @@ unsafe impl Init for T { Ok(()) } } + +/// Smart pointer that can initialize memory in-place. +pub trait InPlaceInit: Sized { + /// Use the given pin-initializer to pin-initialize a `T` inside of a new smart pointer of this + /// type. + /// + /// If `T: !Unpin` it will not be able to move afterwards. + fn try_pin_init(init: impl PinInit) -> Result, E> + where + E: From; + + /// Use the given pin-initializer to pin-initialize a `T` inside of a new smart pointer of this + /// type. + /// + /// If `T: !Unpin` it will not be able to move afterwards. + fn pin_init(init: impl PinInit) -> error::Result> + where + Error: From, + { + // SAFETY: We delegate to `init` and only change the error type. + let init = unsafe { + pin_init_from_closure(|slot| init.__pinned_init(slot).map_err(|e| Error::from(e))) + }; + Self::try_pin_init(init) + } + + /// Use the given initializer to in-place initialize a `T`. + fn try_init(init: impl Init) -> Result + where + E: From; + + /// Use the given initializer to in-place initialize a `T`. + fn init(init: impl Init) -> error::Result + where + Error: From, + { + // SAFETY: We delegate to `init` and only change the error type. + let init = unsafe { + init_from_closure(|slot| init.__pinned_init(slot).map_err(|e| Error::from(e))) + }; + Self::try_init(init) + } +} + +impl InPlaceInit for Box { + #[inline] + fn try_pin_init(init: impl PinInit) -> Result, E> + where + E: From, + { + let mut this = Box::try_new_uninit()?; + let slot = this.as_mut_ptr(); + // SAFETY: When init errors/panics, slot will get deallocated but not dropped, + // slot is valid and will not be moved, because we pin it later. + unsafe { init.__pinned_init(slot)? }; + // SAFETY: All fields have been initialized. + Ok(unsafe { this.assume_init() }.into()) + } + + #[inline] + fn try_init(init: impl Init) -> Result + where + E: From, + { + let mut this = Box::try_new_uninit()?; + let slot = this.as_mut_ptr(); + // SAFETY: When init errors/panics, slot will get deallocated but not dropped, + // slot is valid. + unsafe { init.__init(slot)? }; + // SAFETY: All fields have been initialized. + Ok(unsafe { this.assume_init() }) + } +} + +impl InPlaceInit for UniqueArc { + #[inline] + fn try_pin_init(init: impl PinInit) -> Result, E> + where + E: From, + { + let mut this = UniqueArc::try_new_uninit()?; + let slot = this.as_mut_ptr(); + // SAFETY: When init errors/panics, slot will get deallocated but not dropped, + // slot is valid and will not be moved, because we pin it later. + unsafe { init.__pinned_init(slot)? }; + // SAFETY: All fields have been initialized. + Ok(unsafe { this.assume_init() }.into()) + } + + #[inline] + fn try_init(init: impl Init) -> Result + where + E: From, + { + let mut this = UniqueArc::try_new_uninit()?; + let slot = this.as_mut_ptr(); + // SAFETY: When init errors/panics, slot will get deallocated but not dropped, + // slot is valid. + unsafe { init.__init(slot)? }; + // SAFETY: All fields have been initialized. + Ok(unsafe { this.assume_init() }) + } +} diff --git a/rust/kernel/sync/arc.rs b/rust/kernel/sync/arc.rs index 34d0e7cbe62e..b45769a29541 100644 --- a/rust/kernel/sync/arc.rs +++ b/rust/kernel/sync/arc.rs @@ -17,6 +17,8 @@ use crate::{ bindings, + error::{self, Error}, + init::{InPlaceInit, Init, PinInit}, types::{ForeignOwnable, Opaque}, }; use alloc::boxed::Box; @@ -166,6 +168,28 @@ impl Arc { // `Arc` object. Ok(unsafe { Self::from_inner(Box::leak(inner).into()) }) } + + /// Use the given initializer to in-place initialize a `T`. + /// + /// If `T: !Unpin` it will not be able to move afterwards. + #[inline] + pub fn pin_init(init: impl PinInit) -> error::Result + where + Error: From, + { + UniqueArc::pin_init(init).map(|u| u.into()) + } + + /// Use the given initializer to in-place initialize a `T`. + /// + /// This is equivalent to [`pin_init`], since an [`Arc`] is always pinned. + #[inline] + pub fn init(init: impl Init) -> error::Result + where + Error: From, + { + UniqueArc::init(init).map(|u| u.into()) + } } impl Arc { -- cgit v1.2.3 From d0fdc3961270617826e4794fca1d092853847707 Mon Sep 17 00:00:00 2001 From: Benno Lossin Date: Sat, 8 Apr 2023 12:26:01 +0000 Subject: rust: init: add `PinnedDrop` trait and macros The `PinnedDrop` trait that facilitates destruction of pinned types. It has to be implemented via the `#[pinned_drop]` macro, since the `drop` function should not be called by normal code, only by other destructors. It also only works on structs that are annotated with `#[pin_data(PinnedDrop)]`. Co-developed-by: Gary Guo Signed-off-by: Gary Guo Signed-off-by: Benno Lossin Reviewed-by: Alice Ryhl Reviewed-by: Andreas Hindborg Link: https://lore.kernel.org/r/20230408122429.1103522-10-y86-dev@protonmail.com Signed-off-by: Miguel Ojeda --- rust/kernel/init.rs | 111 +++++++++++++++++ rust/kernel/init/__internal.rs | 15 +++ rust/kernel/init/macros.rs | 264 +++++++++++++++++++++++++++++++++++++++++ rust/macros/lib.rs | 49 ++++++++ rust/macros/pinned_drop.rs | 49 ++++++++ 5 files changed, 488 insertions(+) create mode 100644 rust/macros/pinned_drop.rs (limited to 'rust') diff --git a/rust/kernel/init.rs b/rust/kernel/init.rs index 6499cf5c9c20..37e8159df24d 100644 --- a/rust/kernel/init.rs +++ b/rust/kernel/init.rs @@ -104,6 +104,78 @@ //! } //! ``` //! +//! ## Manual creation of an initializer +//! +//! Often when working with primitives the previous approaches are not sufficient. That is where +//! [`pin_init_from_closure()`] comes in. This `unsafe` function allows you to create a +//! [`impl PinInit`] directly from a closure. Of course you have to ensure that the closure +//! actually does the initialization in the correct way. Here are the things to look out for +//! (we are calling the parameter to the closure `slot`): +//! - when the closure returns `Ok(())`, then it has completed the initialization successfully, so +//! `slot` now contains a valid bit pattern for the type `T`, +//! - when the closure returns `Err(e)`, then the caller may deallocate the memory at `slot`, so +//! you need to take care to clean up anything if your initialization fails mid-way, +//! - you may assume that `slot` will stay pinned even after the closure returns until `drop` of +//! `slot` gets called. +//! +//! ```rust +//! use kernel::{prelude::*, init}; +//! use core::{ptr::addr_of_mut, marker::PhantomPinned, pin::Pin}; +//! # mod bindings { +//! # pub struct foo; +//! # pub unsafe fn init_foo(_ptr: *mut foo) {} +//! # pub unsafe fn destroy_foo(_ptr: *mut foo) {} +//! # pub unsafe fn enable_foo(_ptr: *mut foo, _flags: u32) -> i32 { 0 } +//! # } +//! /// # Invariants +//! /// +//! /// `foo` is always initialized +//! #[pin_data(PinnedDrop)] +//! pub struct RawFoo { +//! #[pin] +//! foo: Opaque, +//! #[pin] +//! _p: PhantomPinned, +//! } +//! +//! impl RawFoo { +//! pub fn new(flags: u32) -> impl PinInit { +//! // SAFETY: +//! // - when the closure returns `Ok(())`, then it has successfully initialized and +//! // enabled `foo`, +//! // - when it returns `Err(e)`, then it has cleaned up before +//! unsafe { +//! init::pin_init_from_closure(move |slot: *mut Self| { +//! // `slot` contains uninit memory, avoid creating a reference. +//! let foo = addr_of_mut!((*slot).foo); +//! +//! // Initialize the `foo` +//! bindings::init_foo(Opaque::raw_get(foo)); +//! +//! // Try to enable it. +//! let err = bindings::enable_foo(Opaque::raw_get(foo), flags); +//! if err != 0 { +//! // Enabling has failed, first clean up the foo and then return the error. +//! bindings::destroy_foo(Opaque::raw_get(foo)); +//! return Err(Error::from_kernel_errno(err)); +//! } +//! +//! // All fields of `RawFoo` have been initialized, since `_p` is a ZST. +//! Ok(()) +//! }) +//! } +//! } +//! } +//! +//! #[pinned_drop] +//! impl PinnedDrop for RawFoo { +//! fn drop(self: Pin<&mut Self>) { +//! // SAFETY: Since `foo` is initialized, destroying is safe. +//! unsafe { bindings::destroy_foo(self.foo.get()) }; +//! } +//! } +//! ``` +//! //! [`sync`]: kernel::sync //! [pinning]: https://doc.rust-lang.org/std/pin/index.html //! [structurally pinned fields]: @@ -1084,3 +1156,42 @@ impl InPlaceInit for UniqueArc { Ok(unsafe { this.assume_init() }) } } + +/// Trait facilitating pinned destruction. +/// +/// Use [`pinned_drop`] to implement this trait safely: +/// +/// ```rust +/// # use kernel::sync::Mutex; +/// use kernel::macros::pinned_drop; +/// use core::pin::Pin; +/// #[pin_data(PinnedDrop)] +/// struct Foo { +/// #[pin] +/// mtx: Mutex, +/// } +/// +/// #[pinned_drop] +/// impl PinnedDrop for Foo { +/// fn drop(self: Pin<&mut Self>) { +/// pr_info!("Foo is being dropped!"); +/// } +/// } +/// ``` +/// +/// # Safety +/// +/// This trait must be implemented via the [`pinned_drop`] proc-macro attribute on the impl. +/// +/// [`pinned_drop`]: kernel::macros::pinned_drop +pub unsafe trait PinnedDrop: __internal::HasPinData { + /// Executes the pinned destructor of this type. + /// + /// While this function is marked safe, it is actually unsafe to call it manually. For this + /// reason it takes an additional parameter. This type can only be constructed by `unsafe` code + /// and thus prevents this function from being called where it should not. + /// + /// This extra parameter will be generated by the `#[pinned_drop]` proc-macro attribute + /// automatically. + fn drop(self: Pin<&mut Self>, only_call_from_drop: __internal::OnlyCallFromDrop); +} diff --git a/rust/kernel/init/__internal.rs b/rust/kernel/init/__internal.rs index a3389a684296..774cb620afa7 100644 --- a/rust/kernel/init/__internal.rs +++ b/rust/kernel/init/__internal.rs @@ -161,3 +161,18 @@ impl Drop for DropGuard { } } } + +/// Token used by `PinnedDrop` to prevent calling the function without creating this unsafely +/// created struct. This is needed, because the `drop` function is safe, but should not be called +/// manually. +pub struct OnlyCallFromDrop(()); + +impl OnlyCallFromDrop { + /// # Safety + /// + /// This function should only be called from the [`Drop::drop`] function and only be used to + /// delegate the destruction to the pinned destructor [`PinnedDrop::drop`] of the same type. + pub unsafe fn new() -> Self { + Self(()) + } +} diff --git a/rust/kernel/init/macros.rs b/rust/kernel/init/macros.rs index 9ef02f5411a6..541cfad1d8be 100644 --- a/rust/kernel/init/macros.rs +++ b/rust/kernel/init/macros.rs @@ -31,6 +31,26 @@ //! pin_init!(Self { t, x: 0 }) //! } //! } +//! +//! #[pin_data(PinnedDrop)] +//! struct Foo { +//! a: usize, +//! #[pin] +//! b: Bar, +//! } +//! +//! #[pinned_drop] +//! impl PinnedDrop for Foo { +//! fn drop(self: Pin<&mut Self>) { +//! println!("{self:p} is getting dropped."); +//! } +//! } +//! +//! let a = 42; +//! let initializer = pin_init!(Foo { +//! a, +//! b <- Bar::new(36), +//! }); //! ``` //! //! This example includes the most common and important features of the pin-init API. @@ -155,6 +175,14 @@ //! #[allow(drop_bounds)] //! impl MustNotImplDrop for T {} //! impl MustNotImplDrop for Bar {} +//! // Here comes a convenience check, if one implemented `PinnedDrop`, but forgot to add it to +//! // `#[pin_data]`, then this will error with the same mechanic as above, this is not needed +//! // for safety, but a good sanity check, since no normal code calls `PinnedDrop::drop`. +//! #[allow(non_camel_case_types)] +//! trait UselessPinnedDropImpl_you_need_to_specify_PinnedDrop {} +//! impl +//! UselessPinnedDropImpl_you_need_to_specify_PinnedDrop for T {} +//! impl UselessPinnedDropImpl_you_need_to_specify_PinnedDrop for Bar {} //! }; //! ``` //! @@ -265,6 +293,210 @@ //! } //! } //! ``` +//! +//! ## `#[pin_data]` on `Foo` +//! +//! Since we already took a look at `#[pin_data]` on `Bar`, this section will only explain the +//! differences/new things in the expansion of the `Foo` definition: +//! +//! ```rust +//! #[pin_data(PinnedDrop)] +//! struct Foo { +//! a: usize, +//! #[pin] +//! b: Bar, +//! } +//! ``` +//! +//! This expands to the following code: +//! +//! ```rust +//! struct Foo { +//! a: usize, +//! b: Bar, +//! } +//! const _: () = { +//! struct __ThePinData { +//! __phantom: ::core::marker::PhantomData Foo>, +//! } +//! impl ::core::clone::Clone for __ThePinData { +//! fn clone(&self) -> Self { +//! *self +//! } +//! } +//! impl ::core::marker::Copy for __ThePinData {} +//! #[allow(dead_code)] +//! impl __ThePinData { +//! unsafe fn b( +//! self, +//! slot: *mut Bar, +//! // Note that this is `PinInit` instead of `Init`, this is because `b` is +//! // structurally pinned, as marked by the `#[pin]` attribute. +//! init: impl ::kernel::init::PinInit, E>, +//! ) -> ::core::result::Result<(), E> { +//! unsafe { ::kernel::init::PinInit::__pinned_init(init, slot) } +//! } +//! unsafe fn a( +//! self, +//! slot: *mut usize, +//! init: impl ::kernel::init::Init, +//! ) -> ::core::result::Result<(), E> { +//! unsafe { ::kernel::init::Init::__init(init, slot) } +//! } +//! } +//! unsafe impl ::kernel::init::__internal::HasPinData for Foo { +//! type PinData = __ThePinData; +//! unsafe fn __pin_data() -> Self::PinData { +//! __ThePinData { +//! __phantom: ::core::marker::PhantomData, +//! } +//! } +//! } +//! unsafe impl ::kernel::init::__internal::PinData for __ThePinData { +//! type Datee = Foo; +//! } +//! #[allow(dead_code)] +//! struct __Unpin<'__pin> { +//! __phantom_pin: ::core::marker::PhantomData &'__pin ()>, +//! __phantom: ::core::marker::PhantomData Foo>, +//! // Since this field is `#[pin]`, it is listed here. +//! b: Bar, +//! } +//! #[doc(hidden)] +//! impl<'__pin> ::core::marker::Unpin for Foo where __Unpin<'__pin>: ::core::marker::Unpin {} +//! // Since we specified `PinnedDrop` as the argument to `#[pin_data]`, we expect `Foo` to +//! // implement `PinnedDrop`. Thus we do not need to prevent `Drop` implementations like +//! // before, instead we implement it here and delegate to `PinnedDrop`. +//! impl ::core::ops::Drop for Foo { +//! fn drop(&mut self) { +//! // Since we are getting dropped, no one else has a reference to `self` and thus we +//! // can assume that we never move. +//! let pinned = unsafe { ::core::pin::Pin::new_unchecked(self) }; +//! // Create the unsafe token that proves that we are inside of a destructor, this +//! // type is only allowed to be created in a destructor. +//! let token = unsafe { ::kernel::init::__internal::OnlyCallFromDrop::new() }; +//! ::kernel::init::PinnedDrop::drop(pinned, token); +//! } +//! } +//! }; +//! ``` +//! +//! ## `#[pinned_drop]` on `impl PinnedDrop for Foo` +//! +//! This macro is used to implement the `PinnedDrop` trait, since that trait is `unsafe` and has an +//! extra parameter that should not be used at all. The macro hides that parameter. +//! +//! Here is the `PinnedDrop` impl for `Foo`: +//! +//! ```rust +//! #[pinned_drop] +//! impl PinnedDrop for Foo { +//! fn drop(self: Pin<&mut Self>) { +//! println!("{self:p} is getting dropped."); +//! } +//! } +//! ``` +//! +//! This expands to the following code: +//! +//! ```rust +//! // `unsafe`, full path and the token parameter are added, everything else stays the same. +//! unsafe impl ::kernel::init::PinnedDrop for Foo { +//! fn drop(self: Pin<&mut Self>, _: ::kernel::init::__internal::OnlyCallFromDrop) { +//! println!("{self:p} is getting dropped."); +//! } +//! } +//! ``` +//! +//! ## `pin_init!` on `Foo` +//! +//! Since we already took a look at `pin_init!` on `Bar`, this section will only explain the +//! differences/new things in the expansion of `pin_init!` on `Foo`: +//! +//! ```rust +//! let a = 42; +//! let initializer = pin_init!(Foo { +//! a, +//! b <- Bar::new(36), +//! }); +//! ``` +//! +//! This expands to the following code: +//! +//! ```rust +//! let a = 42; +//! let initializer = { +//! struct __InitOk; +//! let data = unsafe { +//! use ::kernel::init::__internal::HasPinData; +//! Foo::__pin_data() +//! }; +//! let init = ::kernel::init::__internal::PinData::make_closure::< +//! _, +//! __InitOk, +//! ::core::convert::Infallible, +//! >(data, move |slot| { +//! { +//! struct __InitOk; +//! unsafe { ::core::ptr::write(&raw mut (*slot).a, a) }; +//! let a = &unsafe { ::kernel::init::__internal::DropGuard::new(&raw mut (*slot).a) }; +//! let b = Bar::new(36); +//! // Here we use `data` to access the correct field and require that `b` is of type +//! // `PinInit, Infallible>`. +//! unsafe { data.b(&raw mut (*slot).b, b)? }; +//! let b = &unsafe { ::kernel::init::__internal::DropGuard::new(&raw mut (*slot).b) }; +//! +//! #[allow(unreachable_code, clippy::diverging_sub_expression)] +//! if false { +//! unsafe { +//! ::core::ptr::write( +//! slot, +//! Foo { +//! a: ::core::panic!(), +//! b: ::core::panic!(), +//! }, +//! ); +//! }; +//! } +//! unsafe { ::kernel::init::__internal::DropGuard::forget(a) }; +//! unsafe { ::kernel::init::__internal::DropGuard::forget(b) }; +//! } +//! Ok(__InitOk) +//! }); +//! let init = move |slot| -> ::core::result::Result<(), ::core::convert::Infallible> { +//! init(slot).map(|__InitOk| ()) +//! }; +//! let init = unsafe { +//! ::kernel::init::pin_init_from_closure::<_, ::core::convert::Infallible>(init) +//! }; +//! init +//! }; +//! ``` + +/// Creates a `unsafe impl<...> PinnedDrop for $type` block. +/// +/// See [`PinnedDrop`] for more information. +#[doc(hidden)] +#[macro_export] +macro_rules! __pinned_drop { + ( + @impl_sig($($impl_sig:tt)*), + @impl_body( + $(#[$($attr:tt)*])* + fn drop($($sig:tt)*) { + $($inner:tt)* + } + ), + ) => { + unsafe $($impl_sig)* { + // Inherit all attributes and the type/ident tokens for the signature. + $(#[$($attr)*])* + fn drop($($sig)*, _: $crate::init::__internal::OnlyCallFromDrop) { + $($inner)* + } + } + } +} /// This macro first parses the struct definition such that it separates pinned and not pinned /// fields. Afterwards it declares the struct and implement the `PinData` trait safely. @@ -653,6 +885,38 @@ macro_rules! __pin_data { impl MustNotImplDrop for T {} impl<$($impl_generics)*> MustNotImplDrop for $name<$($ty_generics)*> where $($whr)* {} + // We also take care to prevent users from writing a useless `PinnedDrop` implementation. + // They might implement `PinnedDrop` correctly for the struct, but forget to give + // `PinnedDrop` as the parameter to `#[pin_data]`. + #[allow(non_camel_case_types)] + trait UselessPinnedDropImpl_you_need_to_specify_PinnedDrop {} + impl + UselessPinnedDropImpl_you_need_to_specify_PinnedDrop for T {} + impl<$($impl_generics)*> + UselessPinnedDropImpl_you_need_to_specify_PinnedDrop for $name<$($ty_generics)*> + where $($whr)* {} + }; + // When `PinnedDrop` was specified we just implement `Drop` and delegate. + (drop_prevention: + @name($name:ident), + @impl_generics($($impl_generics:tt)*), + @ty_generics($($ty_generics:tt)*), + @where($($whr:tt)*), + @pinned_drop(PinnedDrop), + ) => { + impl<$($impl_generics)*> ::core::ops::Drop for $name<$($ty_generics)*> + where $($whr)* + { + fn drop(&mut self) { + // SAFETY: Since this is a destructor, `self` will not move after this function + // terminates, since it is inaccessible. + let pinned = unsafe { ::core::pin::Pin::new_unchecked(self) }; + // SAFETY: Since this is a drop function, we can create this token to call the + // pinned destructor of this type. + let token = unsafe { $crate::init::__internal::OnlyCallFromDrop::new() }; + $crate::init::PinnedDrop::drop(pinned, token); + } + } }; // If some other parameter was specified, we emit a readable error. (drop_prevention: diff --git a/rust/macros/lib.rs b/rust/macros/lib.rs index 6d84f2fd0d77..3fc74cb4ea19 100644 --- a/rust/macros/lib.rs +++ b/rust/macros/lib.rs @@ -8,6 +8,7 @@ mod concat_idents; mod helpers; mod module; mod pin_data; +mod pinned_drop; mod vtable; use proc_macro::TokenStream; @@ -180,6 +181,10 @@ pub fn concat_idents(ts: TokenStream) -> TokenStream { /// This macro enables the use of the [`pin_init!`] macro. When pin-initializing a `struct`, /// then `#[pin]` directs the type of initializer that is required. /// +/// If your `struct` implements `Drop`, then you need to add `PinnedDrop` as arguments to this +/// macro, and change your `Drop` implementation to `PinnedDrop` annotated with +/// `#[`[`macro@pinned_drop`]`]`, since dropping pinned values requires extra care. +/// /// # Examples /// /// ```rust,ignore @@ -191,9 +196,53 @@ pub fn concat_idents(ts: TokenStream) -> TokenStream { /// } /// ``` /// +/// ```rust,ignore +/// #[pin_data(PinnedDrop)] +/// struct DriverData { +/// #[pin] +/// queue: Mutex>, +/// buf: Box<[u8; 1024 * 1024]>, +/// raw_info: *mut Info, +/// } +/// +/// #[pinned_drop] +/// impl PinnedDrop for DriverData { +/// fn drop(self: Pin<&mut Self>) { +/// unsafe { bindings::destroy_info(self.raw_info) }; +/// } +/// } +/// ``` +/// /// [`pin_init!`]: ../kernel/macro.pin_init.html // ^ cannot use direct link, since `kernel` is not a dependency of `macros`. #[proc_macro_attribute] pub fn pin_data(inner: TokenStream, item: TokenStream) -> TokenStream { pin_data::pin_data(inner, item) } + +/// Used to implement `PinnedDrop` safely. +/// +/// Only works on structs that are annotated via `#[`[`macro@pin_data`]`]`. +/// +/// # Examples +/// +/// ```rust,ignore +/// #[pin_data(PinnedDrop)] +/// struct DriverData { +/// #[pin] +/// queue: Mutex>, +/// buf: Box<[u8; 1024 * 1024]>, +/// raw_info: *mut Info, +/// } +/// +/// #[pinned_drop] +/// impl PinnedDrop for DriverData { +/// fn drop(self: Pin<&mut Self>) { +/// unsafe { bindings::destroy_info(self.raw_info) }; +/// } +/// } +/// ``` +#[proc_macro_attribute] +pub fn pinned_drop(args: TokenStream, input: TokenStream) -> TokenStream { + pinned_drop::pinned_drop(args, input) +} diff --git a/rust/macros/pinned_drop.rs b/rust/macros/pinned_drop.rs new file mode 100644 index 000000000000..88fb72b20660 --- /dev/null +++ b/rust/macros/pinned_drop.rs @@ -0,0 +1,49 @@ +// SPDX-License-Identifier: Apache-2.0 OR MIT + +use proc_macro::{TokenStream, TokenTree}; + +pub(crate) fn pinned_drop(_args: TokenStream, input: TokenStream) -> TokenStream { + let mut toks = input.into_iter().collect::>(); + assert!(!toks.is_empty()); + // Ensure that we have an `impl` item. + assert!(matches!(&toks[0], TokenTree::Ident(i) if i.to_string() == "impl")); + // Ensure that we are implementing `PinnedDrop`. + let mut nesting: usize = 0; + let mut pinned_drop_idx = None; + for (i, tt) in toks.iter().enumerate() { + match tt { + TokenTree::Punct(p) if p.as_char() == '<' => { + nesting += 1; + } + TokenTree::Punct(p) if p.as_char() == '>' => { + nesting = nesting.checked_sub(1).unwrap(); + continue; + } + _ => {} + } + if i >= 1 && nesting == 0 { + // Found the end of the generics, this should be `PinnedDrop`. + assert!( + matches!(tt, TokenTree::Ident(i) if i.to_string() == "PinnedDrop"), + "expected 'PinnedDrop', found: '{:?}'", + tt + ); + pinned_drop_idx = Some(i); + break; + } + } + let idx = pinned_drop_idx + .unwrap_or_else(|| panic!("Expected an `impl` block implementing `PinnedDrop`.")); + // Fully qualify the `PinnedDrop`, as to avoid any tampering. + toks.splice(idx..idx, quote!(::kernel::init::)); + // Take the `{}` body and call the declarative macro. + if let Some(TokenTree::Group(last)) = toks.pop() { + let last = last.stream(); + quote!(::kernel::__pinned_drop! { + @impl_sig(#(#toks)*), + @impl_body(#last), + }) + } else { + TokenStream::from_iter(toks) + } +} -- cgit v1.2.3 From 6841d45a303029c54d6ad1ebb5dc72f7b2a74700 Mon Sep 17 00:00:00 2001 From: Benno Lossin Date: Sat, 8 Apr 2023 12:26:07 +0000 Subject: rust: init: add `stack_pin_init!` macro The `stack_pin_init!` macro allows pin-initializing a value on the stack. It accepts a `impl PinInit` to initialize a `T`. It allows propagating any errors via `?` or handling it normally via `match`. Signed-off-by: Benno Lossin Reviewed-by: Alice Ryhl Reviewed-by: Andreas Hindborg Reviewed-by: Gary Guo Link: https://lore.kernel.org/r/20230408122429.1103522-11-y86-dev@protonmail.com Signed-off-by: Miguel Ojeda --- rust/kernel/init.rs | 140 +++++++++++++++++++++++++++++++++++++++-- rust/kernel/init/__internal.rs | 57 +++++++++++++++++ 2 files changed, 191 insertions(+), 6 deletions(-) (limited to 'rust') diff --git a/rust/kernel/init.rs b/rust/kernel/init.rs index 37e8159df24d..99751375e7c8 100644 --- a/rust/kernel/init.rs +++ b/rust/kernel/init.rs @@ -12,7 +12,8 @@ //! //! To initialize a `struct` with an in-place constructor you will need two things: //! - an in-place constructor, -//! - a memory location that can hold your `struct`. +//! - a memory location that can hold your `struct` (this can be the [stack], an [`Arc`], +//! [`UniqueArc`], [`Box`] or any other smart pointer that implements [`InPlaceInit`]). //! //! To get an in-place constructor there are generally three options: //! - directly creating an in-place constructor using the [`pin_init!`] macro, @@ -180,6 +181,7 @@ //! [pinning]: https://doc.rust-lang.org/std/pin/index.html //! [structurally pinned fields]: //! https://doc.rust-lang.org/std/pin/index.html#pinning-is-structural-for-field +//! [stack]: crate::stack_pin_init //! [`Arc`]: crate::sync::Arc //! [`impl PinInit`]: PinInit //! [`impl PinInit`]: PinInit @@ -202,6 +204,132 @@ pub mod __internal; #[doc(hidden)] pub mod macros; +/// Initialize and pin a type directly on the stack. +/// +/// # Examples +/// +/// ```rust +/// # #![allow(clippy::disallowed_names, clippy::new_ret_no_self)] +/// # use kernel::{init, pin_init, stack_pin_init, init::*, sync::Mutex, new_mutex}; +/// # use macros::pin_data; +/// # use core::pin::Pin; +/// #[pin_data] +/// struct Foo { +/// #[pin] +/// a: Mutex, +/// b: Bar, +/// } +/// +/// #[pin_data] +/// struct Bar { +/// x: u32, +/// } +/// +/// stack_pin_init!(let foo = pin_init!(Foo { +/// a <- new_mutex!(42), +/// b: Bar { +/// x: 64, +/// }, +/// })); +/// let foo: Pin<&mut Foo> = foo; +/// pr_info!("a: {}", &*foo.a.lock()); +/// ``` +/// +/// # Syntax +/// +/// A normal `let` binding with optional type annotation. The expression is expected to implement +/// [`PinInit`]/[`Init`] with the error type [`Infallible`]. If you want to use a different error +/// type, then use [`stack_try_pin_init!`]. +#[macro_export] +macro_rules! stack_pin_init { + (let $var:ident $(: $t:ty)? = $val:expr) => { + let val = $val; + let mut $var = ::core::pin::pin!($crate::init::__internal::StackInit$(::<$t>)?::uninit()); + let mut $var = match $crate::init::__internal::StackInit::init($var, val) { + Ok(res) => res, + Err(x) => { + let x: ::core::convert::Infallible = x; + match x {} + } + }; + }; +} + +/// Initialize and pin a type directly on the stack. +/// +/// # Examples +/// +/// ```rust +/// # #![allow(clippy::disallowed_names, clippy::new_ret_no_self)] +/// # use kernel::{init, pin_init, stack_try_pin_init, init::*, sync::Mutex, new_mutex}; +/// # use macros::pin_data; +/// # use core::{alloc::AllocError, pin::Pin}; +/// #[pin_data] +/// struct Foo { +/// #[pin] +/// a: Mutex, +/// b: Box, +/// } +/// +/// struct Bar { +/// x: u32, +/// } +/// +/// stack_try_pin_init!(let foo: Result, AllocError> = pin_init!(Foo { +/// a <- new_mutex!(42), +/// b: Box::try_new(Bar { +/// x: 64, +/// })?, +/// })); +/// let foo = foo.unwrap(); +/// pr_info!("a: {}", &*foo.a.lock()); +/// ``` +/// +/// ```rust +/// # #![allow(clippy::disallowed_names, clippy::new_ret_no_self)] +/// # use kernel::{init, pin_init, stack_try_pin_init, init::*, sync::Mutex, new_mutex}; +/// # use macros::pin_data; +/// # use core::{alloc::AllocError, pin::Pin}; +/// #[pin_data] +/// struct Foo { +/// #[pin] +/// a: Mutex, +/// b: Box, +/// } +/// +/// struct Bar { +/// x: u32, +/// } +/// +/// stack_try_pin_init!(let foo: Pin<&mut Foo> =? pin_init!(Foo { +/// a <- new_mutex!(42), +/// b: Box::try_new(Bar { +/// x: 64, +/// })?, +/// })); +/// pr_info!("a: {}", &*foo.a.lock()); +/// # Ok::<_, AllocError>(()) +/// ``` +/// +/// # Syntax +/// +/// A normal `let` binding with optional type annotation. The expression is expected to implement +/// [`PinInit`]/[`Init`]. This macro assigns a result to the given variable, adding a `?` after the +/// `=` will propagate this error. +#[macro_export] +macro_rules! stack_try_pin_init { + (let $var:ident $(: $t:ty)? = $val:expr) => { + let val = $val; + let mut $var = ::core::pin::pin!($crate::init::__internal::StackInit$(::<$t>)?::uninit()); + let mut $var = $crate::init::__internal::StackInit::init($var, val); + }; + (let $var:ident $(: $t:ty)? =? $val:expr) => { + let val = $val; + let mut $var = ::core::pin::pin!($crate::init::__internal::StackInit$(::<$t>)?::uninit()); + let mut $var = $crate::init::__internal::StackInit::init($var, val)?; + }; +} + /// Construct an in-place, pinned initializer for `struct`s. /// /// This macro defaults the error to [`Infallible`]. If you need [`Error`], then use @@ -913,8 +1041,8 @@ macro_rules! try_init { /// A pin-initializer for the type `T`. /// /// To use this initializer, you will need a suitable memory location that can hold a `T`. This can -/// be [`Box`], [`Arc`], [`UniqueArc`]. Use the [`InPlaceInit::pin_init`] function of a -/// smart pointer like [`Arc`] on this. +/// be [`Box`], [`Arc`], [`UniqueArc`] or even the stack (see [`stack_pin_init!`]). Use the +/// [`InPlaceInit::pin_init`] function of a smart pointer like [`Arc`] on this. /// /// Also see the [module description](self). /// @@ -949,9 +1077,9 @@ pub unsafe trait PinInit: Sized { /// An initializer for `T`. /// /// To use this initializer, you will need a suitable memory location that can hold a `T`. This can -/// be [`Box`], [`Arc`], [`UniqueArc`]. Use the [`InPlaceInit::init`] function of a smart -/// pointer like [`Arc`] on this. Because [`PinInit`] is a super trait, you can -/// use every function that takes it as well. +/// be [`Box`], [`Arc`], [`UniqueArc`] or even the stack (see [`stack_pin_init!`]). Use the +/// [`InPlaceInit::init`] function of a smart pointer like [`Arc`] on this. Because +/// [`PinInit`] is a super trait, you can use every function that takes it as well. /// /// Also see the [module description](self). /// diff --git a/rust/kernel/init/__internal.rs b/rust/kernel/init/__internal.rs index 774cb620afa7..44751fb62b51 100644 --- a/rust/kernel/init/__internal.rs +++ b/rust/kernel/init/__internal.rs @@ -112,6 +112,63 @@ unsafe impl HasInitData for T { } } +/// Stack initializer helper type. Use [`stack_pin_init`] instead of this primitive. +/// +/// # Invariants +/// +/// If `self.is_init` is true, then `self.value` is initialized. +/// +/// [`stack_pin_init`]: kernel::stack_pin_init +pub struct StackInit { + value: MaybeUninit, + is_init: bool, +} + +impl Drop for StackInit { + #[inline] + fn drop(&mut self) { + if self.is_init { + // SAFETY: As we are being dropped, we only call this once. And since `self.is_init` is + // true, `self.value` is initialized. + unsafe { self.value.assume_init_drop() }; + } + } +} + +impl StackInit { + /// Creates a new [`StackInit`] that is uninitialized. Use [`stack_pin_init`] instead of this + /// primitive. + /// + /// [`stack_pin_init`]: kernel::stack_pin_init + #[inline] + pub fn uninit() -> Self { + Self { + value: MaybeUninit::uninit(), + is_init: false, + } + } + + /// Initializes the contents and returns the result. + #[inline] + pub fn init(self: Pin<&mut Self>, init: impl PinInit) -> Result, E> { + // SAFETY: We never move out of `this`. + let this = unsafe { Pin::into_inner_unchecked(self) }; + // The value is currently initialized, so it needs to be dropped before we can reuse + // the memory (this is a safety guarantee of `Pin`). + if this.is_init { + this.is_init = false; + // SAFETY: `this.is_init` was true and therefore `this.value` is initialized. + unsafe { this.value.assume_init_drop() }; + } + // SAFETY: The memory slot is valid and this type ensures that it will stay pinned. + unsafe { init.__pinned_init(this.value.as_mut_ptr())? }; + // INVARIANT: `this.value` is initialized above. + this.is_init = true; + // SAFETY: The slot is now pinned, since we will never give access to `&mut T`. + Ok(unsafe { Pin::new_unchecked(this.value.assume_init_mut()) }) + } +} + /// When a value of this type is dropped, it drops a `T`. /// /// Can be forgotten to prevent the drop. -- cgit v1.2.3 From 38cde0bd7b6772003a37b9aa6822568409556ee9 Mon Sep 17 00:00:00 2001 From: Benno Lossin Date: Sat, 8 Apr 2023 12:26:12 +0000 Subject: rust: init: add `Zeroable` trait and `init::zeroed` function Add the `Zeroable` trait which marks types that can be initialized by writing `0x00` to every byte of the type. Also add the `init::zeroed` function that creates an initializer for a `Zeroable` type that writes `0x00` to every byte. Signed-off-by: Benno Lossin Reviewed-by: Alice Ryhl Reviewed-by: Gary Guo Reviewed-by: Andreas Hindborg Link: https://lore.kernel.org/r/20230408122429.1103522-12-y86-dev@protonmail.com Signed-off-by: Miguel Ojeda --- rust/kernel/init.rs | 97 +++++++++++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 95 insertions(+), 2 deletions(-) (limited to 'rust') diff --git a/rust/kernel/init.rs b/rust/kernel/init.rs index 99751375e7c8..ffd539e2f5ef 100644 --- a/rust/kernel/init.rs +++ b/rust/kernel/init.rs @@ -195,8 +195,14 @@ use crate::{ }; use alloc::boxed::Box; use core::{ - alloc::AllocError, cell::Cell, convert::Infallible, marker::PhantomData, mem::MaybeUninit, - pin::Pin, ptr, + alloc::AllocError, + cell::Cell, + convert::Infallible, + marker::PhantomData, + mem::MaybeUninit, + num::*, + pin::Pin, + ptr::{self, NonNull}, }; #[doc(hidden)] @@ -1323,3 +1329,90 @@ pub unsafe trait PinnedDrop: __internal::HasPinData { /// automatically. fn drop(self: Pin<&mut Self>, only_call_from_drop: __internal::OnlyCallFromDrop); } + +/// Marker trait for types that can be initialized by writing just zeroes. +/// +/// # Safety +/// +/// The bit pattern consisting of only zeroes is a valid bit pattern for this type. In other words, +/// this is not UB: +/// +/// ```rust,ignore +/// let val: Self = unsafe { core::mem::zeroed() }; +/// ``` +pub unsafe trait Zeroable {} + +/// Create a new zeroed T. +/// +/// The returned initializer will write `0x00` to every byte of the given `slot`. +#[inline] +pub fn zeroed() -> impl Init { + // SAFETY: Because `T: Zeroable`, all bytes zero is a valid bit pattern for `T` + // and because we write all zeroes, the memory is initialized. + unsafe { + init_from_closure(|slot: *mut T| { + slot.write_bytes(0, 1); + Ok(()) + }) + } +} + +macro_rules! impl_zeroable { + ($($({$($generics:tt)*})? $t:ty, )*) => { + $(unsafe impl$($($generics)*)? Zeroable for $t {})* + }; +} + +impl_zeroable! { + // SAFETY: All primitives that are allowed to be zero. + bool, + char, + u8, u16, u32, u64, u128, usize, + i8, i16, i32, i64, i128, isize, + f32, f64, + + // SAFETY: These are ZSTs, there is nothing to zero. + {} PhantomData, core::marker::PhantomPinned, Infallible, (), + + // SAFETY: Type is allowed to take any value, including all zeros. + {} MaybeUninit, + + // SAFETY: All zeros is equivalent to `None` (option layout optimization guarantee). + Option, Option, Option, Option, + Option, Option, + Option, Option, Option, Option, + Option, Option, + + // SAFETY: All zeros is equivalent to `None` (option layout optimization guarantee). + // + // In this case we are allowed to use `T: ?Sized`, since all zeros is the `None` variant. + {} Option>, + {} Option>, + + // SAFETY: `null` pointer is valid. + // + // We cannot use `T: ?Sized`, since the VTABLE pointer part of fat pointers is not allowed to be + // null. + // + // When `Pointee` gets stabilized, we could use + // `T: ?Sized where ::Metadata: Zeroable` + {} *mut T, {} *const T, + + // SAFETY: `null` pointer is valid and the metadata part of these fat pointers is allowed to be + // zero. + {} *mut [T], {} *const [T], *mut str, *const str, + + // SAFETY: `T` is `Zeroable`. + {} [T; N], {} Wrapping, +} + +macro_rules! impl_tuple_zeroable { + ($(,)?) => {}; + ($first:ident, $($t:ident),* $(,)?) => { + // SAFETY: All elements are zeroable and padding can be zero. + unsafe impl<$first: Zeroable, $($t: Zeroable),*> Zeroable for ($first, $($t),*) {} + impl_tuple_zeroable!($($t),* ,); + } +} + +impl_tuple_zeroable!(A, B, C, D, E, F, G, H, I, J); -- cgit v1.2.3 From 8586f1acd314a47d68d189331606ca235a05b972 Mon Sep 17 00:00:00 2001 From: Benno Lossin Date: Sat, 8 Apr 2023 12:26:17 +0000 Subject: rust: prelude: add `pin-init` API items to prelude Add `pin-init` API macros and traits to the prelude. Signed-off-by: Benno Lossin Reviewed-by: Gary Guo Reviewed-by: Alice Ryhl Reviewed-by: Andreas Hindborg Link: https://lore.kernel.org/r/20230408122429.1103522-13-y86-dev@protonmail.com Signed-off-by: Miguel Ojeda --- rust/kernel/prelude.rs | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) (limited to 'rust') diff --git a/rust/kernel/prelude.rs b/rust/kernel/prelude.rs index 0bc1c97e5604..fcdc511d2ce8 100644 --- a/rust/kernel/prelude.rs +++ b/rust/kernel/prelude.rs @@ -18,7 +18,7 @@ pub use core::pin::Pin; pub use alloc::{boxed::Box, vec::Vec}; #[doc(no_inline)] -pub use macros::{module, vtable}; +pub use macros::{module, pin_data, pinned_drop, vtable}; pub use super::build_assert; @@ -27,8 +27,12 @@ pub use super::build_assert; pub use super::dbg; pub use super::{pr_alert, pr_crit, pr_debug, pr_emerg, pr_err, pr_info, pr_notice, pr_warn}; +pub use super::{init, pin_init, try_init, try_pin_init}; + pub use super::static_assert; pub use super::error::{code::*, Error, Result}; pub use super::{str::CStr, ThisModule}; + +pub use super::init::{InPlaceInit, Init, PinInit}; -- cgit v1.2.3 From 692e8935e23efab6c5d5fc4b003816b33c8082f7 Mon Sep 17 00:00:00 2001 From: Benno Lossin Date: Sat, 8 Apr 2023 12:26:22 +0000 Subject: rust: types: add `Opaque::ffi_init` This function allows to easily initialize `Opaque` with the pin-init API. `Opaque::ffi_init` takes a closure and returns a pin-initializer. This pin-initiailizer calls the given closure with a pointer to the inner `T`. Co-developed-by: Gary Guo Signed-off-by: Gary Guo Signed-off-by: Benno Lossin Reviewed-by: Andreas Hindborg Reviewed-by: Alice Ryhl Link: https://lore.kernel.org/r/20230408122429.1103522-14-y86-dev@protonmail.com [ Fixed typo. ] Signed-off-by: Miguel Ojeda --- rust/kernel/init.rs | 9 +++++++++ rust/kernel/types.rs | 20 ++++++++++++++++++++ 2 files changed, 29 insertions(+) (limited to 'rust') diff --git a/rust/kernel/init.rs b/rust/kernel/init.rs index ffd539e2f5ef..a1298c8bbda0 100644 --- a/rust/kernel/init.rs +++ b/rust/kernel/init.rs @@ -177,6 +177,14 @@ //! } //! ``` //! +//! For the special case where initializing a field is a single FFI-function call that cannot fail, +//! there exist the helper function [`Opaque::ffi_init`]. This function initialize a single +//! [`Opaque`] field by just delegating to the supplied closure. You can use these in combination +//! with [`pin_init!`]. +//! +//! For more information on how to use [`pin_init_from_closure()`], take a look at the uses inside +//! the `kernel` crate. The [`sync`] module is a good starting point. +//! //! [`sync`]: kernel::sync //! [pinning]: https://doc.rust-lang.org/std/pin/index.html //! [structurally pinned fields]: @@ -187,6 +195,7 @@ //! [`impl PinInit`]: PinInit //! [`impl Init`]: Init //! [`Opaque`]: kernel::types::Opaque +//! [`Opaque::ffi_init`]: kernel::types::Opaque::ffi_init //! [`pin_data`]: ::macros::pin_data use crate::{ diff --git a/rust/kernel/types.rs b/rust/kernel/types.rs index ff2b2fac951d..a4b1e3778da7 100644 --- a/rust/kernel/types.rs +++ b/rust/kernel/types.rs @@ -2,6 +2,7 @@ //! Kernel types. +use crate::init::{self, PinInit}; use alloc::boxed::Box; use core::{ cell::UnsafeCell, @@ -234,6 +235,25 @@ impl Opaque { Self(MaybeUninit::uninit()) } + /// Creates a pin-initializer from the given initializer closure. + /// + /// The returned initializer calls the given closure with the pointer to the inner `T` of this + /// `Opaque`. Since this memory is uninitialized, the closure is not allowed to read from it. + /// + /// This function is safe, because the `T` inside of an `Opaque` is allowed to be + /// uninitialized. Additionally, access to the inner `T` requires `unsafe`, so the caller needs + /// to verify at that point that the inner value is valid. + pub fn ffi_init(init_func: impl FnOnce(*mut T)) -> impl PinInit { + // SAFETY: We contain a `MaybeUninit`, so it is OK for the `init_func` to not fully + // initialize the `T`. + unsafe { + init::pin_init_from_closure::<_, ::core::convert::Infallible>(move |slot| { + init_func(Self::raw_get(slot)); + Ok(()) + }) + } + } + /// Returns a raw pointer to the opaque data. pub fn get(&self) -> *mut T { UnsafeCell::raw_get(self.0.as_ptr()) -- cgit v1.2.3 From 701608bd030a888f654862295a49c5d0f42f864c Mon Sep 17 00:00:00 2001 From: Benno Lossin Date: Sat, 8 Apr 2023 12:26:27 +0000 Subject: rust: sync: reduce stack usage of `UniqueArc::try_new_uninit` `UniqueArc::try_new_uninit` calls `Arc::try_new(MaybeUninit::uninit())`. This results in the uninitialized memory being placed on the stack, which may be arbitrarily large due to the generic `T` and thus could cause a stack overflow for large types. Change the implementation to use the pin-init API which enables in-place initialization. In particular it avoids having to first construct and then move the uninitialized memory from the stack into the final location. Signed-off-by: Benno Lossin Reviewed-by: Alice Ryhl Reviewed-by: Gary Guo Reviewed-by: Andreas Hindborg Link: https://lore.kernel.org/r/20230408122429.1103522-15-y86-dev@protonmail.com Signed-off-by: Miguel Ojeda --- rust/kernel/lib.rs | 1 - rust/kernel/sync/arc.rs | 16 +++++++++++++--- 2 files changed, 13 insertions(+), 4 deletions(-) (limited to 'rust') diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs index 821bd067151c..2d7606135ef6 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -28,7 +28,6 @@ #[cfg(not(CONFIG_RUST))] compile_error!("Missing kernel configuration for conditional compilation"); -#[allow(unused_extern_crates)] // Allow proc-macros to refer to `::kernel` inside the `kernel` crate (this crate). extern crate self as kernel; diff --git a/rust/kernel/sync/arc.rs b/rust/kernel/sync/arc.rs index b45769a29541..de36d55e81d8 100644 --- a/rust/kernel/sync/arc.rs +++ b/rust/kernel/sync/arc.rs @@ -18,7 +18,8 @@ use crate::{ bindings, error::{self, Error}, - init::{InPlaceInit, Init, PinInit}, + init::{self, InPlaceInit, Init, PinInit}, + try_init, types::{ForeignOwnable, Opaque}, }; use alloc::boxed::Box; @@ -31,6 +32,7 @@ use core::{ pin::Pin, ptr::NonNull, }; +use macros::pin_data; mod std_vendor; @@ -125,6 +127,7 @@ pub struct Arc { _p: PhantomData>, } +#[pin_data] #[repr(C)] struct ArcInner { refcount: Opaque, @@ -505,9 +508,16 @@ impl UniqueArc { /// Tries to allocate a new [`UniqueArc`] instance whose contents are not initialised yet. pub fn try_new_uninit() -> Result>, AllocError> { - Ok(UniqueArc::> { + // INVARIANT: The refcount is initialised to a non-zero value. + let inner = Box::try_init::(try_init!(ArcInner { + // SAFETY: There are no safety requirements for this FFI call. + refcount: Opaque::new(unsafe { bindings::REFCOUNT_INIT(1) }), + data <- init::uninit::(), + }? AllocError))?; + Ok(UniqueArc { // INVARIANT: The newly-created object has a ref-count of 1. - inner: Arc::try_new(MaybeUninit::uninit())?, + // SAFETY: The pointer from the `Box` is valid. + inner: unsafe { Arc::from_inner(Box::leak(inner).into()) }, }) } } -- cgit v1.2.3 From 1944caa8e8dcb2d93d99d8364719ad8d07aa163f Mon Sep 17 00:00:00 2001 From: Benno Lossin Date: Sat, 8 Apr 2023 12:26:33 +0000 Subject: rust: sync: add functions for initializing `UniqueArc>` Add two functions `init_with` and `pin_init_with` to `UniqueArc>` to initialize the memory of already allocated `UniqueArc`s. This is useful when you want to allocate memory check some condition inside of a context where allocation is forbidden and then conditionally initialize an object. Signed-off-by: Benno Lossin Reviewed-by: Gary Guo Reviewed-by: Alice Ryhl Reviewed-by: Andreas Hindborg Link: https://lore.kernel.org/r/20230408122429.1103522-16-y86-dev@protonmail.com Signed-off-by: Miguel Ojeda --- rust/kernel/sync/arc.rs | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) (limited to 'rust') diff --git a/rust/kernel/sync/arc.rs b/rust/kernel/sync/arc.rs index de36d55e81d8..e6d206242465 100644 --- a/rust/kernel/sync/arc.rs +++ b/rust/kernel/sync/arc.rs @@ -544,6 +544,30 @@ impl UniqueArc> { inner: unsafe { Arc::from_inner(inner.cast()) }, } } + + /// Initialize `self` using the given initializer. + pub fn init_with(mut self, init: impl Init) -> core::result::Result, E> { + // SAFETY: The supplied pointer is valid for initialization. + match unsafe { init.__init(self.as_mut_ptr()) } { + // SAFETY: Initialization completed successfully. + Ok(()) => Ok(unsafe { self.assume_init() }), + Err(err) => Err(err), + } + } + + /// Pin-initialize `self` using the given pin-initializer. + pub fn pin_init_with( + mut self, + init: impl PinInit, + ) -> core::result::Result>, E> { + // SAFETY: The supplied pointer is valid for initialization and we will later pin the value + // to ensure it does not move. + match unsafe { init.__pinned_init(self.as_mut_ptr()) } { + // SAFETY: Initialization completed successfully. + Ok(()) => Ok(unsafe { self.assume_init() }.into()), + Err(err) => Err(err), + } + } } impl From> for Pin> { -- cgit v1.2.3 From 52a7f2deb4be8706bcbd16bba1d70eb2b5735d19 Mon Sep 17 00:00:00 2001 From: Benno Lossin Date: Thu, 13 Apr 2023 10:02:17 +0000 Subject: rust: init: broaden the blanket impl of `Init` This makes it possible to use `T` as a `impl Init` for every error type `E` instead of just `Infallible`. Signed-off-by: Benno Lossin Reviewed-by: Gary Guo Reviewed-by: Martin Rodriguez Reboredo Link: https://lore.kernel.org/r/20230413100157.740697-1-benno.lossin@proton.me Signed-off-by: Miguel Ojeda --- rust/kernel/init.rs | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'rust') diff --git a/rust/kernel/init.rs b/rust/kernel/init.rs index a1298c8bbda0..4ebfb08dab11 100644 --- a/rust/kernel/init.rs +++ b/rust/kernel/init.rs @@ -1190,8 +1190,8 @@ pub fn uninit() -> impl Init, E> { } // SAFETY: Every type can be initialized by-value. -unsafe impl Init for T { - unsafe fn __init(self, slot: *mut T) -> Result<(), Infallible> { +unsafe impl Init for T { + unsafe fn __init(self, slot: *mut T) -> Result<(), E> { unsafe { slot.write(self) }; Ok(()) } -- cgit v1.2.3 From 6ea5aa08857a81be7114b3c21d6aa6db0bc95f99 Mon Sep 17 00:00:00 2001 From: Wedson Almeida Filho Date: Tue, 11 Apr 2023 02:45:31 -0300 Subject: rust: sync: introduce `LockClassKey` It is a wrapper around C's `lock_class_key`, which is used by the synchronisation primitives that are checked with lockdep. This is in preparation for introducing Rust abstractions for these primitives. Cc: Peter Zijlstra Cc: Ingo Molnar Cc: Will Deacon Cc: Waiman Long Reviewed-by: Martin Rodriguez Reboredo Co-developed-by: Boqun Feng Signed-off-by: Boqun Feng Signed-off-by: Wedson Almeida Filho Reviewed-by: Gary Guo Reviewed-by: Benno Lossin Link: https://lore.kernel.org/r/20230411054543.21278-1-wedsonaf@gmail.com Signed-off-by: Miguel Ojeda --- rust/kernel/sync.rs | 45 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 45 insertions(+) (limited to 'rust') diff --git a/rust/kernel/sync.rs b/rust/kernel/sync.rs index 33da23e3076d..541d235ffbeb 100644 --- a/rust/kernel/sync.rs +++ b/rust/kernel/sync.rs @@ -5,6 +5,51 @@ //! This module contains the kernel APIs related to synchronisation that have been ported or //! wrapped for usage by Rust code in the kernel. +use crate::types::Opaque; + mod arc; pub use arc::{Arc, ArcBorrow, UniqueArc}; + +/// Represents a lockdep class. It's a wrapper around C's `lock_class_key`. +#[repr(transparent)] +pub struct LockClassKey(Opaque); + +// SAFETY: `bindings::lock_class_key` is designed to be used concurrently from multiple threads and +// provides its own synchronization. +unsafe impl Sync for LockClassKey {} + +impl LockClassKey { + /// Creates a new lock class key. + pub const fn new() -> Self { + Self(Opaque::uninit()) + } + + #[allow(dead_code)] + pub(crate) fn as_ptr(&self) -> *mut bindings::lock_class_key { + self.0.get() + } +} + +/// Defines a new static lock class and returns a pointer to it. +#[doc(hidden)] +#[macro_export] +macro_rules! static_lock_class { + () => {{ + static CLASS: $crate::sync::LockClassKey = $crate::sync::LockClassKey::new(); + &CLASS + }}; +} + +/// Returns the given string, if one is provided, otherwise generates one based on the source code +/// location. +#[doc(hidden)] +#[macro_export] +macro_rules! optional_name { + () => { + $crate::c_str!(::core::concat!(::core::file!(), ":", ::core::line!())) + }; + ($name:literal) => { + $crate::c_str!($name) + }; +} -- cgit v1.2.3 From 76d4bd591e1101df69c44c819041e374c63f1194 Mon Sep 17 00:00:00 2001 From: Wedson Almeida Filho Date: Tue, 11 Apr 2023 02:45:32 -0300 Subject: rust: sync: introduce `Lock` and `Guard` They are generic Rust implementations of a lock and a lock guard that contain code that is common to all locks. Different backends will be introduced in subsequent commits. Reviewed-by: Martin Rodriguez Reboredo Suggested-by: Gary Guo Signed-off-by: Wedson Almeida Filho Link: https://lore.kernel.org/r/20230411054543.21278-2-wedsonaf@gmail.com [ Fixed typo. ] Signed-off-by: Miguel Ojeda --- rust/kernel/sync.rs | 2 +- rust/kernel/sync/lock.rs | 162 +++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 163 insertions(+), 1 deletion(-) create mode 100644 rust/kernel/sync/lock.rs (limited to 'rust') diff --git a/rust/kernel/sync.rs b/rust/kernel/sync.rs index 541d235ffbeb..81b0998eaa18 100644 --- a/rust/kernel/sync.rs +++ b/rust/kernel/sync.rs @@ -8,6 +8,7 @@ use crate::types::Opaque; mod arc; +pub mod lock; pub use arc::{Arc, ArcBorrow, UniqueArc}; @@ -25,7 +26,6 @@ impl LockClassKey { Self(Opaque::uninit()) } - #[allow(dead_code)] pub(crate) fn as_ptr(&self) -> *mut bindings::lock_class_key { self.0.get() } diff --git a/rust/kernel/sync/lock.rs b/rust/kernel/sync/lock.rs new file mode 100644 index 000000000000..f2dbdc496c23 --- /dev/null +++ b/rust/kernel/sync/lock.rs @@ -0,0 +1,162 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! Generic kernel lock and guard. +//! +//! It contains a generic Rust lock and guard that allow for different backends (e.g., mutexes, +//! spinlocks, raw spinlocks) to be provided with minimal effort. + +use super::LockClassKey; +use crate::{bindings, init::PinInit, pin_init, str::CStr, types::Opaque}; +use core::{cell::UnsafeCell, marker::PhantomData, marker::PhantomPinned}; +use macros::pin_data; + +/// The "backend" of a lock. +/// +/// It is the actual implementation of the lock, without the need to repeat patterns used in all +/// locks. +/// +/// # Safety +/// +/// - Implementers must ensure that only one thread/CPU may access the protected data once the lock +/// is owned, that is, between calls to `lock` and `unlock`. +pub unsafe trait Backend { + /// The state required by the lock. + type State; + + /// The state required to be kept between lock and unlock. + type GuardState; + + /// Initialises the lock. + /// + /// # Safety + /// + /// `ptr` must be valid for write for the duration of the call, while `name` and `key` must + /// remain valid for read indefinitely. + unsafe fn init( + ptr: *mut Self::State, + name: *const core::ffi::c_char, + key: *mut bindings::lock_class_key, + ); + + /// Acquires the lock, making the caller its owner. + /// + /// # Safety + /// + /// Callers must ensure that [`Backend::init`] has been previously called. + #[must_use] + unsafe fn lock(ptr: *mut Self::State) -> Self::GuardState; + + /// Releases the lock, giving up its ownership. + /// + /// # Safety + /// + /// It must only be called by the current owner of the lock. + unsafe fn unlock(ptr: *mut Self::State, guard_state: &Self::GuardState); +} + +/// A mutual exclusion primitive. +/// +/// Exposes one of the kernel locking primitives. Which one is exposed depends on the lock backend +/// specified as the generic parameter `B`. +#[pin_data] +pub struct Lock { + /// The kernel lock object. + #[pin] + state: Opaque, + + /// Some locks are known to be self-referential (e.g., mutexes), while others are architecture + /// or config defined (e.g., spinlocks). So we conservatively require them to be pinned in case + /// some architecture uses self-references now or in the future. + #[pin] + _pin: PhantomPinned, + + /// The data protected by the lock. + data: UnsafeCell, +} + +// SAFETY: `Lock` can be transferred across thread boundaries iff the data it protects can. +unsafe impl Send for Lock {} + +// SAFETY: `Lock` serialises the interior mutability it provides, so it is `Sync` as long as the +// data it protects is `Send`. +unsafe impl Sync for Lock {} + +impl Lock { + /// Constructs a new lock initialiser. + #[allow(clippy::new_ret_no_self)] + pub fn new(t: T, name: &'static CStr, key: &'static LockClassKey) -> impl PinInit { + pin_init!(Self { + data: UnsafeCell::new(t), + _pin: PhantomPinned, + // SAFETY: `slot` is valid while the closure is called and both `name` and `key` have + // static lifetimes so they live indefinitely. + state <- Opaque::ffi_init(|slot| unsafe { + B::init(slot, name.as_char_ptr(), key.as_ptr()) + }), + }) + } +} + +impl Lock { + /// Acquires the lock and gives the caller access to the data protected by it. + pub fn lock(&self) -> Guard<'_, T, B> { + // SAFETY: The constructor of the type calls `init`, so the existence of the object proves + // that `init` was called. + let state = unsafe { B::lock(self.state.get()) }; + // SAFETY: The lock was just acquired. + unsafe { Guard::new(self, state) } + } +} + +/// A lock guard. +/// +/// Allows mutual exclusion primitives that implement the `Backend` trait to automatically unlock +/// when a guard goes out of scope. It also provides a safe and convenient way to access the data +/// protected by the lock. +#[must_use = "the lock unlocks immediately when the guard is unused"] +pub struct Guard<'a, T: ?Sized, B: Backend> { + pub(crate) lock: &'a Lock, + pub(crate) state: B::GuardState, + _not_send: PhantomData<*mut ()>, +} + +// SAFETY: `Guard` is sync when the data protected by the lock is also sync. +unsafe impl Sync for Guard<'_, T, B> {} + +impl core::ops::Deref for Guard<'_, T, B> { + type Target = T; + + fn deref(&self) -> &Self::Target { + // SAFETY: The caller owns the lock, so it is safe to deref the protected data. + unsafe { &*self.lock.data.get() } + } +} + +impl core::ops::DerefMut for Guard<'_, T, B> { + fn deref_mut(&mut self) -> &mut Self::Target { + // SAFETY: The caller owns the lock, so it is safe to deref the protected data. + unsafe { &mut *self.lock.data.get() } + } +} + +impl Drop for Guard<'_, T, B> { + fn drop(&mut self) { + // SAFETY: The caller owns the lock, so it is safe to unlock it. + unsafe { B::unlock(self.lock.state.get(), &self.state) }; + } +} + +impl<'a, T: ?Sized, B: Backend> Guard<'a, T, B> { + /// Constructs a new immutable lock guard. + /// + /// # Safety + /// + /// The caller must ensure that it owns the lock. + pub(crate) unsafe fn new(lock: &'a Lock, state: B::GuardState) -> Self { + Self { + lock, + state, + _not_send: PhantomData, + } + } +} -- cgit v1.2.3 From 6d20d629c6d8575be98eeebe49a16fb2d7b32350 Mon Sep 17 00:00:00 2001 From: Wedson Almeida Filho Date: Tue, 11 Apr 2023 02:45:33 -0300 Subject: rust: lock: introduce `Mutex` This is the `struct mutex` lock backend and allows Rust code to use the kernel mutex idiomatically. Cc: Peter Zijlstra Cc: Ingo Molnar Cc: Will Deacon Cc: Waiman Long Reviewed-by: Martin Rodriguez Reboredo Signed-off-by: Wedson Almeida Filho Link: https://lore.kernel.org/r/20230411054543.21278-3-wedsonaf@gmail.com Signed-off-by: Miguel Ojeda --- rust/helpers.c | 7 +++ rust/kernel/sync.rs | 1 + rust/kernel/sync/lock.rs | 2 + rust/kernel/sync/lock/mutex.rs | 118 +++++++++++++++++++++++++++++++++++++++++ 4 files changed, 128 insertions(+) create mode 100644 rust/kernel/sync/lock/mutex.rs (limited to 'rust') diff --git a/rust/helpers.c b/rust/helpers.c index 04b9be46e887..86af099d2d66 100644 --- a/rust/helpers.c +++ b/rust/helpers.c @@ -22,6 +22,7 @@ #include #include #include +#include __noreturn void rust_helper_BUG(void) { @@ -29,6 +30,12 @@ __noreturn void rust_helper_BUG(void) } EXPORT_SYMBOL_GPL(rust_helper_BUG); +void rust_helper_mutex_lock(struct mutex *lock) +{ + mutex_lock(lock); +} +EXPORT_SYMBOL_GPL(rust_helper_mutex_lock); + refcount_t rust_helper_REFCOUNT_INIT(int n) { return (refcount_t)REFCOUNT_INIT(n); diff --git a/rust/kernel/sync.rs b/rust/kernel/sync.rs index 81b0998eaa18..693f0b7f4e4f 100644 --- a/rust/kernel/sync.rs +++ b/rust/kernel/sync.rs @@ -11,6 +11,7 @@ mod arc; pub mod lock; pub use arc::{Arc, ArcBorrow, UniqueArc}; +pub use lock::mutex::Mutex; /// Represents a lockdep class. It's a wrapper around C's `lock_class_key`. #[repr(transparent)] diff --git a/rust/kernel/sync/lock.rs b/rust/kernel/sync/lock.rs index f2dbdc496c23..2ea512a8dfab 100644 --- a/rust/kernel/sync/lock.rs +++ b/rust/kernel/sync/lock.rs @@ -10,6 +10,8 @@ use crate::{bindings, init::PinInit, pin_init, str::CStr, types::Opaque}; use core::{cell::UnsafeCell, marker::PhantomData, marker::PhantomPinned}; use macros::pin_data; +pub mod mutex; + /// The "backend" of a lock. /// /// It is the actual implementation of the lock, without the need to repeat patterns used in all diff --git a/rust/kernel/sync/lock/mutex.rs b/rust/kernel/sync/lock/mutex.rs new file mode 100644 index 000000000000..923472f04af4 --- /dev/null +++ b/rust/kernel/sync/lock/mutex.rs @@ -0,0 +1,118 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! A kernel mutex. +//! +//! This module allows Rust code to use the kernel's `struct mutex`. + +use crate::bindings; + +/// Creates a [`Mutex`] initialiser with the given name and a newly-created lock class. +/// +/// It uses the name if one is given, otherwise it generates one based on the file name and line +/// number. +#[macro_export] +macro_rules! new_mutex { + ($inner:expr $(, $name:literal)? $(,)?) => { + $crate::sync::Mutex::new( + $inner, $crate::optional_name!($($name)?), $crate::static_lock_class!()) + }; +} + +/// A mutual exclusion primitive. +/// +/// Exposes the kernel's [`struct mutex`]. When multiple threads attempt to lock the same mutex, +/// only one at a time is allowed to progress, the others will block (sleep) until the mutex is +/// unlocked, at which point another thread will be allowed to wake up and make progress. +/// +/// Since it may block, [`Mutex`] needs to be used with care in atomic contexts. +/// +/// Instances of [`Mutex`] need a lock class and to be pinned. The recommended way to create such +/// instances is with the [`pin_init`](crate::pin_init) and [`new_mutex`] macros. +/// +/// # Examples +/// +/// The following example shows how to declare, allocate and initialise a struct (`Example`) that +/// contains an inner struct (`Inner`) that is protected by a mutex. +/// +/// ``` +/// use kernel::{init::InPlaceInit, init::PinInit, new_mutex, pin_init, sync::Mutex}; +/// +/// struct Inner { +/// a: u32, +/// b: u32, +/// } +/// +/// #[pin_data] +/// struct Example { +/// c: u32, +/// #[pin] +/// d: Mutex, +/// } +/// +/// impl Example { +/// fn new() -> impl PinInit { +/// pin_init!(Self { +/// c: 10, +/// d <- new_mutex!(Inner { a: 20, b: 30 }), +/// }) +/// } +/// } +/// +/// // Allocate a boxed `Example`. +/// let e = Box::pin_init(Example::new())?; +/// assert_eq!(e.c, 10); +/// assert_eq!(e.d.lock().a, 20); +/// assert_eq!(e.d.lock().b, 30); +/// ``` +/// +/// The following example shows how to use interior mutability to modify the contents of a struct +/// protected by a mutex despite only having a shared reference: +/// +/// ``` +/// use kernel::sync::Mutex; +/// +/// struct Example { +/// a: u32, +/// b: u32, +/// } +/// +/// fn example(m: &Mutex) { +/// let mut guard = m.lock(); +/// guard.a += 10; +/// guard.b += 20; +/// } +/// ``` +/// +/// [`struct mutex`]: ../../../../include/linux/mutex.h +pub type Mutex = super::Lock; + +/// A kernel `struct mutex` lock backend. +pub struct MutexBackend; + +// SAFETY: The underlying kernel `struct mutex` object ensures mutual exclusion. +unsafe impl super::Backend for MutexBackend { + type State = bindings::mutex; + type GuardState = (); + + unsafe fn init( + ptr: *mut Self::State, + name: *const core::ffi::c_char, + key: *mut bindings::lock_class_key, + ) { + // SAFETY: The safety requirements ensure that `ptr` is valid for writes, and `name` and + // `key` are valid for read indefinitely. + unsafe { bindings::__mutex_init(ptr, name, key) } + } + + unsafe fn lock(ptr: *mut Self::State) -> Self::GuardState { + // SAFETY: The safety requirements of this function ensure that `ptr` points to valid + // memory, and that it has been initialised before. + unsafe { bindings::mutex_lock(ptr) }; + } + + unsafe fn unlock(ptr: *mut Self::State, _guard_state: &Self::GuardState) { + // SAFETY: The safety requirements of this function ensure that `ptr` is valid and that the + // caller is the owner of the mutex. + unsafe { bindings::mutex_unlock(ptr) }; + } +} -- cgit v1.2.3 From c6d917a498bfef603f41bfc4d31e9699bb2909fc Mon Sep 17 00:00:00 2001 From: Wedson Almeida Filho Date: Wed, 19 Apr 2023 14:44:26 -0300 Subject: rust: lock: introduce `SpinLock` This is the `spinlock_t` lock backend and allows Rust code to use the kernel spinlock idiomatically. Cc: Peter Zijlstra Cc: Ingo Molnar Cc: Will Deacon Cc: Waiman Long Reviewed-by: Martin Rodriguez Reboredo Signed-off-by: Wedson Almeida Filho Link: https://lore.kernel.org/r/20230419174426.132207-1-wedsonaf@gmail.com Signed-off-by: Miguel Ojeda --- rust/helpers.c | 24 ++++++++ rust/kernel/sync.rs | 2 +- rust/kernel/sync/lock.rs | 1 + rust/kernel/sync/lock/spinlock.rs | 116 ++++++++++++++++++++++++++++++++++++++ 4 files changed, 142 insertions(+), 1 deletion(-) create mode 100644 rust/kernel/sync/lock/spinlock.rs (limited to 'rust') diff --git a/rust/helpers.c b/rust/helpers.c index 86af099d2d66..446e3cfdb935 100644 --- a/rust/helpers.c +++ b/rust/helpers.c @@ -23,6 +23,7 @@ #include #include #include +#include __noreturn void rust_helper_BUG(void) { @@ -36,6 +37,29 @@ void rust_helper_mutex_lock(struct mutex *lock) } EXPORT_SYMBOL_GPL(rust_helper_mutex_lock); +void rust_helper___spin_lock_init(spinlock_t *lock, const char *name, + struct lock_class_key *key) +{ +#ifdef CONFIG_DEBUG_SPINLOCK + __raw_spin_lock_init(spinlock_check(lock), name, key, LD_WAIT_CONFIG); +#else + spin_lock_init(lock); +#endif +} +EXPORT_SYMBOL_GPL(rust_helper___spin_lock_init); + +void rust_helper_spin_lock(spinlock_t *lock) +{ + spin_lock(lock); +} +EXPORT_SYMBOL_GPL(rust_helper_spin_lock); + +void rust_helper_spin_unlock(spinlock_t *lock) +{ + spin_unlock(lock); +} +EXPORT_SYMBOL_GPL(rust_helper_spin_unlock); + refcount_t rust_helper_REFCOUNT_INIT(int n) { return (refcount_t)REFCOUNT_INIT(n); diff --git a/rust/kernel/sync.rs b/rust/kernel/sync.rs index 693f0b7f4e4f..c997ff7e951e 100644 --- a/rust/kernel/sync.rs +++ b/rust/kernel/sync.rs @@ -11,7 +11,7 @@ mod arc; pub mod lock; pub use arc::{Arc, ArcBorrow, UniqueArc}; -pub use lock::mutex::Mutex; +pub use lock::{mutex::Mutex, spinlock::SpinLock}; /// Represents a lockdep class. It's a wrapper around C's `lock_class_key`. #[repr(transparent)] diff --git a/rust/kernel/sync/lock.rs b/rust/kernel/sync/lock.rs index 2ea512a8dfab..3c166e08f3d4 100644 --- a/rust/kernel/sync/lock.rs +++ b/rust/kernel/sync/lock.rs @@ -11,6 +11,7 @@ use core::{cell::UnsafeCell, marker::PhantomData, marker::PhantomPinned}; use macros::pin_data; pub mod mutex; +pub mod spinlock; /// The "backend" of a lock. /// diff --git a/rust/kernel/sync/lock/spinlock.rs b/rust/kernel/sync/lock/spinlock.rs new file mode 100644 index 000000000000..a52d20fc9755 --- /dev/null +++ b/rust/kernel/sync/lock/spinlock.rs @@ -0,0 +1,116 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! A kernel spinlock. +//! +//! This module allows Rust code to use the kernel's `spinlock_t`. + +use crate::bindings; + +/// Creates a [`SpinLock`] initialiser with the given name and a newly-created lock class. +/// +/// It uses the name if one is given, otherwise it generates one based on the file name and line +/// number. +#[macro_export] +macro_rules! new_spinlock { + ($inner:expr $(, $name:literal)? $(,)?) => { + $crate::sync::SpinLock::new( + $inner, $crate::optional_name!($($name)?), $crate::static_lock_class!()) + }; +} + +/// A spinlock. +/// +/// Exposes the kernel's [`spinlock_t`]. When multiple CPUs attempt to lock the same spinlock, only +/// one at a time is allowed to progress, the others will block (spinning) until the spinlock is +/// unlocked, at which point another CPU will be allowed to make progress. +/// +/// Instances of [`SpinLock`] need a lock class and to be pinned. The recommended way to create such +/// instances is with the [`pin_init`](crate::pin_init) and [`new_spinlock`] macros. +/// +/// # Examples +/// +/// The following example shows how to declare, allocate and initialise a struct (`Example`) that +/// contains an inner struct (`Inner`) that is protected by a spinlock. +/// +/// ``` +/// use kernel::{init::InPlaceInit, init::PinInit, new_spinlock, pin_init, sync::SpinLock}; +/// +/// struct Inner { +/// a: u32, +/// b: u32, +/// } +/// +/// #[pin_data] +/// struct Example { +/// c: u32, +/// #[pin] +/// d: SpinLock, +/// } +/// +/// impl Example { +/// fn new() -> impl PinInit { +/// pin_init!(Self { +/// c: 10, +/// d <- new_spinlock!(Inner { a: 20, b: 30 }), +/// }) +/// } +/// } +/// +/// // Allocate a boxed `Example`. +/// let e = Box::pin_init(Example::new())?; +/// assert_eq!(e.c, 10); +/// assert_eq!(e.d.lock().a, 20); +/// assert_eq!(e.d.lock().b, 30); +/// ``` +/// +/// The following example shows how to use interior mutability to modify the contents of a struct +/// protected by a spinlock despite only having a shared reference: +/// +/// ``` +/// use kernel::sync::SpinLock; +/// +/// struct Example { +/// a: u32, +/// b: u32, +/// } +/// +/// fn example(m: &SpinLock) { +/// let mut guard = m.lock(); +/// guard.a += 10; +/// guard.b += 20; +/// } +/// ``` +/// +/// [`spinlock_t`]: ../../../../include/linux/spinlock.h +pub type SpinLock = super::Lock; + +/// A kernel `spinlock_t` lock backend. +pub struct SpinLockBackend; + +// SAFETY: The underlying kernel `spinlock_t` object ensures mutual exclusion. +unsafe impl super::Backend for SpinLockBackend { + type State = bindings::spinlock_t; + type GuardState = (); + + unsafe fn init( + ptr: *mut Self::State, + name: *const core::ffi::c_char, + key: *mut bindings::lock_class_key, + ) { + // SAFETY: The safety requirements ensure that `ptr` is valid for writes, and `name` and + // `key` are valid for read indefinitely. + unsafe { bindings::__spin_lock_init(ptr, name, key) } + } + + unsafe fn lock(ptr: *mut Self::State) -> Self::GuardState { + // SAFETY: The safety requirements of this function ensure that `ptr` points to valid + // memory, and that it has been initialised before. + unsafe { bindings::spin_lock(ptr) } + } + + unsafe fn unlock(ptr: *mut Self::State, _guard_state: &Self::GuardState) { + // SAFETY: The safety requirements of this function ensure that `ptr` is valid and that the + // caller is the owner of the mutex. + unsafe { bindings::spin_unlock(ptr) } + } +} -- cgit v1.2.3 From f1fbd6a864d417443cdacd6bfdb7fd626993da7e Mon Sep 17 00:00:00 2001 From: Wedson Almeida Filho Date: Tue, 11 Apr 2023 02:45:38 -0300 Subject: rust: introduce `ARef` This is an owned reference to an object that is always ref-counted. This is meant to be used in wrappers for C types that have their own ref counting functions, for example, tasks, files, inodes, dentries, etc. Reviewed-by: Martin Rodriguez Reboredo Signed-off-by: Wedson Almeida Filho Reviewed-by: Gary Guo Link: https://lore.kernel.org/r/20230411054543.21278-8-wedsonaf@gmail.com Signed-off-by: Miguel Ojeda --- rust/kernel/types.rs | 107 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 107 insertions(+) (limited to 'rust') diff --git a/rust/kernel/types.rs b/rust/kernel/types.rs index a4b1e3778da7..29db59d6119a 100644 --- a/rust/kernel/types.rs +++ b/rust/kernel/types.rs @@ -6,8 +6,10 @@ use crate::init::{self, PinInit}; use alloc::boxed::Box; use core::{ cell::UnsafeCell, + marker::PhantomData, mem::MaybeUninit, ops::{Deref, DerefMut}, + ptr::NonNull, }; /// Used to transfer ownership to and from foreign (non-Rust) languages. @@ -268,6 +270,111 @@ impl Opaque { } } +/// Types that are _always_ reference counted. +/// +/// It allows such types to define their own custom ref increment and decrement functions. +/// Additionally, it allows users to convert from a shared reference `&T` to an owned reference +/// [`ARef`]. +/// +/// This is usually implemented by wrappers to existing structures on the C side of the code. For +/// Rust code, the recommendation is to use [`Arc`](crate::sync::Arc) to create reference-counted +/// instances of a type. +/// +/// # Safety +/// +/// Implementers must ensure that increments to the reference count keep the object alive in memory +/// at least until matching decrements are performed. +/// +/// Implementers must also ensure that all instances are reference-counted. (Otherwise they +/// won't be able to honour the requirement that [`AlwaysRefCounted::inc_ref`] keep the object +/// alive.) +pub unsafe trait AlwaysRefCounted { + /// Increments the reference count on the object. + fn inc_ref(&self); + + /// Decrements the reference count on the object. + /// + /// Frees the object when the count reaches zero. + /// + /// # Safety + /// + /// Callers must ensure that there was a previous matching increment to the reference count, + /// and that the object is no longer used after its reference count is decremented (as it may + /// result in the object being freed), unless the caller owns another increment on the refcount + /// (e.g., it calls [`AlwaysRefCounted::inc_ref`] twice, then calls + /// [`AlwaysRefCounted::dec_ref`] once). + unsafe fn dec_ref(obj: NonNull); +} + +/// An owned reference to an always-reference-counted object. +/// +/// The object's reference count is automatically decremented when an instance of [`ARef`] is +/// dropped. It is also automatically incremented when a new instance is created via +/// [`ARef::clone`]. +/// +/// # Invariants +/// +/// The pointer stored in `ptr` is non-null and valid for the lifetime of the [`ARef`] instance. In +/// particular, the [`ARef`] instance owns an increment on the underlying object's reference count. +pub struct ARef { + ptr: NonNull, + _p: PhantomData, +} + +impl ARef { + /// Creates a new instance of [`ARef`]. + /// + /// It takes over an increment of the reference count on the underlying object. + /// + /// # Safety + /// + /// Callers must ensure that the reference count was incremented at least once, and that they + /// are properly relinquishing one increment. That is, if there is only one increment, callers + /// must not use the underlying object anymore -- it is only safe to do so via the newly + /// created [`ARef`]. + pub unsafe fn from_raw(ptr: NonNull) -> Self { + // INVARIANT: The safety requirements guarantee that the new instance now owns the + // increment on the refcount. + Self { + ptr, + _p: PhantomData, + } + } +} + +impl Clone for ARef { + fn clone(&self) -> Self { + self.inc_ref(); + // SAFETY: We just incremented the refcount above. + unsafe { Self::from_raw(self.ptr) } + } +} + +impl Deref for ARef { + type Target = T; + + fn deref(&self) -> &Self::Target { + // SAFETY: The type invariants guarantee that the object is valid. + unsafe { self.ptr.as_ref() } + } +} + +impl From<&T> for ARef { + fn from(b: &T) -> Self { + b.inc_ref(); + // SAFETY: We just incremented the refcount above. + unsafe { Self::from_raw(NonNull::from(b)) } + } +} + +impl Drop for ARef { + fn drop(&mut self) { + // SAFETY: The type invariants guarantee that the `ARef` owns the reference we're about to + // decrement. + unsafe { T::dec_ref(self.ptr) }; + } +} + /// A sum type that always holds either a value of type `L` or `R`. pub enum Either { /// Constructs an instance of [`Either`] containing a value of type `L`. -- cgit v1.2.3 From 313c4281bc9dfa98d76a71b16a684af1c52e7751 Mon Sep 17 00:00:00 2001 From: Wedson Almeida Filho Date: Tue, 11 Apr 2023 02:45:39 -0300 Subject: rust: add basic `Task` It is an abstraction for C's `struct task_struct`. It implements `AlwaysRefCounted`, so the refcount of the wrapped object is managed safely on the Rust side. Cc: Ingo Molnar Cc: Peter Zijlstra Reviewed-by: Martin Rodriguez Reboredo Signed-off-by: Wedson Almeida Filho Link: https://lore.kernel.org/r/20230411054543.21278-9-wedsonaf@gmail.com Signed-off-by: Miguel Ojeda --- rust/bindings/bindings_helper.h | 1 + rust/helpers.c | 19 +++++++++++ rust/kernel/lib.rs | 1 + rust/kernel/task.rs | 75 +++++++++++++++++++++++++++++++++++++++++ 4 files changed, 96 insertions(+) create mode 100644 rust/kernel/task.rs (limited to 'rust') diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helper.h index 75d85bd6c592..03656a44a83f 100644 --- a/rust/bindings/bindings_helper.h +++ b/rust/bindings/bindings_helper.h @@ -8,6 +8,7 @@ #include #include +#include /* `bindgen` gets confused at certain things. */ const gfp_t BINDINGS_GFP_KERNEL = GFP_KERNEL; diff --git a/rust/helpers.c b/rust/helpers.c index 446e3cfdb935..6e5b2c953d36 100644 --- a/rust/helpers.c +++ b/rust/helpers.c @@ -24,6 +24,7 @@ #include #include #include +#include __noreturn void rust_helper_BUG(void) { @@ -60,6 +61,12 @@ void rust_helper_spin_unlock(spinlock_t *lock) } EXPORT_SYMBOL_GPL(rust_helper_spin_unlock); +int rust_helper_signal_pending(struct task_struct *t) +{ + return signal_pending(t); +} +EXPORT_SYMBOL_GPL(rust_helper_signal_pending); + refcount_t rust_helper_REFCOUNT_INIT(int n) { return (refcount_t)REFCOUNT_INIT(n); @@ -96,6 +103,18 @@ long rust_helper_PTR_ERR(__force const void *ptr) } EXPORT_SYMBOL_GPL(rust_helper_PTR_ERR); +void rust_helper_get_task_struct(struct task_struct *t) +{ + get_task_struct(t); +} +EXPORT_SYMBOL_GPL(rust_helper_get_task_struct); + +void rust_helper_put_task_struct(struct task_struct *t) +{ + put_task_struct(t); +} +EXPORT_SYMBOL_GPL(rust_helper_put_task_struct); + /* * We use `bindgen`'s `--size_t-is-usize` option to bind the C `size_t` type * as the Rust `usize` type, so we can use it in contexts where Rust diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs index 2d7606135ef6..ee27e10da479 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -44,6 +44,7 @@ mod static_assert; pub mod std_vendor; pub mod str; pub mod sync; +pub mod task; pub mod types; #[doc(hidden)] diff --git a/rust/kernel/task.rs b/rust/kernel/task.rs new file mode 100644 index 000000000000..d70cad131956 --- /dev/null +++ b/rust/kernel/task.rs @@ -0,0 +1,75 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! Tasks (threads and processes). +//! +//! C header: [`include/linux/sched.h`](../../../../include/linux/sched.h). + +use crate::{bindings, types::Opaque}; +use core::ptr; + +/// Wraps the kernel's `struct task_struct`. +/// +/// # Invariants +/// +/// All instances are valid tasks created by the C portion of the kernel. +/// +/// Instances of this type are always ref-counted, that is, a call to `get_task_struct` ensures +/// that the allocation remains valid at least until the matching call to `put_task_struct`. +#[repr(transparent)] +pub struct Task(pub(crate) Opaque); + +// SAFETY: It's OK to access `Task` through references from other threads because we're either +// accessing properties that don't change (e.g., `pid`, `group_leader`) or that are properly +// synchronised by C code (e.g., `signal_pending`). +unsafe impl Sync for Task {} + +/// The type of process identifiers (PIDs). +type Pid = bindings::pid_t; + +impl Task { + /// Returns the group leader of the given task. + pub fn group_leader(&self) -> &Task { + // SAFETY: By the type invariant, we know that `self.0` is a valid task. Valid tasks always + // have a valid group_leader. + let ptr = unsafe { *ptr::addr_of!((*self.0.get()).group_leader) }; + + // SAFETY: The lifetime of the returned task reference is tied to the lifetime of `self`, + // and given that a task has a reference to its group leader, we know it must be valid for + // the lifetime of the returned task reference. + unsafe { &*ptr.cast() } + } + + /// Returns the PID of the given task. + pub fn pid(&self) -> Pid { + // SAFETY: By the type invariant, we know that `self.0` is a valid task. Valid tasks always + // have a valid pid. + unsafe { *ptr::addr_of!((*self.0.get()).pid) } + } + + /// Determines whether the given task has pending signals. + pub fn signal_pending(&self) -> bool { + // SAFETY: By the type invariant, we know that `self.0` is valid. + unsafe { bindings::signal_pending(self.0.get()) != 0 } + } + + /// Wakes up the task. + pub fn wake_up(&self) { + // SAFETY: By the type invariant, we know that `self.0.get()` is non-null and valid. + // And `wake_up_process` is safe to be called for any valid task, even if the task is + // running. + unsafe { bindings::wake_up_process(self.0.get()) }; + } +} + +// SAFETY: The type invariants guarantee that `Task` is always ref-counted. +unsafe impl crate::types::AlwaysRefCounted for Task { + fn inc_ref(&self) { + // SAFETY: The existence of a shared reference means that the refcount is nonzero. + unsafe { bindings::get_task_struct(self.0.get()) }; + } + + unsafe fn dec_ref(obj: ptr::NonNull) { + // SAFETY: The safety requirements guarantee that the refcount is nonzero. + unsafe { bindings::put_task_struct(obj.cast().as_ptr()) } + } +} -- cgit v1.2.3 From 8da7a2b7432e8f043f04515895687f72cdb3e0a8 Mon Sep 17 00:00:00 2001 From: Wedson Almeida Filho Date: Tue, 11 Apr 2023 02:45:40 -0300 Subject: rust: introduce `current` This allows Rust code to get a reference to the current task without having to increment the refcount, but still guaranteeing memory safety. Cc: Ingo Molnar Cc: Peter Zijlstra Reviewed-by: Martin Rodriguez Reboredo Signed-off-by: Wedson Almeida Filho Link: https://lore.kernel.org/r/20230411054543.21278-10-wedsonaf@gmail.com Signed-off-by: Miguel Ojeda --- rust/helpers.c | 6 ++++ rust/kernel/prelude.rs | 2 ++ rust/kernel/task.rs | 82 +++++++++++++++++++++++++++++++++++++++++++++++++- 3 files changed, 89 insertions(+), 1 deletion(-) (limited to 'rust') diff --git a/rust/helpers.c b/rust/helpers.c index 6e5b2c953d36..2cb7b82053d8 100644 --- a/rust/helpers.c +++ b/rust/helpers.c @@ -103,6 +103,12 @@ long rust_helper_PTR_ERR(__force const void *ptr) } EXPORT_SYMBOL_GPL(rust_helper_PTR_ERR); +struct task_struct *rust_helper_get_current(void) +{ + return current; +} +EXPORT_SYMBOL_GPL(rust_helper_get_current); + void rust_helper_get_task_struct(struct task_struct *t) { get_task_struct(t); diff --git a/rust/kernel/prelude.rs b/rust/kernel/prelude.rs index fcdc511d2ce8..c28587d68ebc 100644 --- a/rust/kernel/prelude.rs +++ b/rust/kernel/prelude.rs @@ -36,3 +36,5 @@ pub use super::error::{code::*, Error, Result}; pub use super::{str::CStr, ThisModule}; pub use super::init::{InPlaceInit, Init, PinInit}; + +pub use super::current; diff --git a/rust/kernel/task.rs b/rust/kernel/task.rs index d70cad131956..526d29a0ae27 100644 --- a/rust/kernel/task.rs +++ b/rust/kernel/task.rs @@ -5,7 +5,17 @@ //! C header: [`include/linux/sched.h`](../../../../include/linux/sched.h). use crate::{bindings, types::Opaque}; -use core::ptr; +use core::{marker::PhantomData, ops::Deref, ptr}; + +/// Returns the currently running task. +#[macro_export] +macro_rules! current { + () => { + // SAFETY: Deref + addr-of below create a temporary `TaskRef` that cannot outlive the + // caller. + unsafe { &*$crate::task::Task::current() } + }; +} /// Wraps the kernel's `struct task_struct`. /// @@ -15,6 +25,42 @@ use core::ptr; /// /// Instances of this type are always ref-counted, that is, a call to `get_task_struct` ensures /// that the allocation remains valid at least until the matching call to `put_task_struct`. +/// +/// # Examples +/// +/// The following is an example of getting the PID of the current thread with zero additional cost +/// when compared to the C version: +/// +/// ``` +/// let pid = current!().pid(); +/// ``` +/// +/// Getting the PID of the current process, also zero additional cost: +/// +/// ``` +/// let pid = current!().group_leader().pid(); +/// ``` +/// +/// Getting the current task and storing it in some struct. The reference count is automatically +/// incremented when creating `State` and decremented when it is dropped: +/// +/// ``` +/// use kernel::{task::Task, types::ARef}; +/// +/// struct State { +/// creator: ARef, +/// index: u32, +/// } +/// +/// impl State { +/// fn new() -> Self { +/// Self { +/// creator: current!().into(), +/// index: 0, +/// } +/// } +/// } +/// ``` #[repr(transparent)] pub struct Task(pub(crate) Opaque); @@ -27,6 +73,40 @@ unsafe impl Sync for Task {} type Pid = bindings::pid_t; impl Task { + /// Returns a task reference for the currently executing task/thread. + /// + /// The recommended way to get the current task/thread is to use the + /// [`current`](crate::current) macro because it is safe. + /// + /// # Safety + /// + /// Callers must ensure that the returned object doesn't outlive the current task/thread. + pub unsafe fn current() -> impl Deref { + struct TaskRef<'a> { + task: &'a Task, + _not_send: PhantomData<*mut ()>, + } + + impl Deref for TaskRef<'_> { + type Target = Task; + + fn deref(&self) -> &Self::Target { + self.task + } + } + + // SAFETY: Just an FFI call with no additional safety requirements. + let ptr = unsafe { bindings::get_current() }; + + TaskRef { + // SAFETY: If the current thread is still running, the current task is valid. Given + // that `TaskRef` is not `Send`, we know it cannot be transferred to another thread + // (where it could potentially outlive the caller). + task: unsafe { &*ptr.cast() }, + _not_send: PhantomData, + } + } + /// Returns the group leader of the given task. pub fn group_leader(&self) -> &Task { // SAFETY: By the type invariant, we know that `self.0` is a valid task. Valid tasks always -- cgit v1.2.3 From 7b1f55e3a984aaed0121f90f9f8580f18b7b561e Mon Sep 17 00:00:00 2001 From: Wedson Almeida Filho Date: Tue, 11 Apr 2023 02:45:43 -0300 Subject: rust: sync: introduce `LockedBy` This allows us to have data protected by a lock despite not being wrapped by it. Access is granted by providing evidence that the lock is held by the caller. Reviewed-by: Martin Rodriguez Reboredo Signed-off-by: Wedson Almeida Filho Reviewed-by: Benno Lossin Link: https://lore.kernel.org/r/20230411054543.21278-13-wedsonaf@gmail.com Signed-off-by: Miguel Ojeda --- rust/kernel/sync.rs | 2 + rust/kernel/sync/lock.rs | 2 +- rust/kernel/sync/locked_by.rs | 156 ++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 159 insertions(+), 1 deletion(-) create mode 100644 rust/kernel/sync/locked_by.rs (limited to 'rust') diff --git a/rust/kernel/sync.rs b/rust/kernel/sync.rs index c997ff7e951e..5393b0d76619 100644 --- a/rust/kernel/sync.rs +++ b/rust/kernel/sync.rs @@ -9,9 +9,11 @@ use crate::types::Opaque; mod arc; pub mod lock; +mod locked_by; pub use arc::{Arc, ArcBorrow, UniqueArc}; pub use lock::{mutex::Mutex, spinlock::SpinLock}; +pub use locked_by::LockedBy; /// Represents a lockdep class. It's a wrapper around C's `lock_class_key`. #[repr(transparent)] diff --git a/rust/kernel/sync/lock.rs b/rust/kernel/sync/lock.rs index 3c166e08f3d4..46e3328b67a6 100644 --- a/rust/kernel/sync/lock.rs +++ b/rust/kernel/sync/lock.rs @@ -74,7 +74,7 @@ pub struct Lock { _pin: PhantomPinned, /// The data protected by the lock. - data: UnsafeCell, + pub(crate) data: UnsafeCell, } // SAFETY: `Lock` can be transferred across thread boundaries iff the data it protects can. diff --git a/rust/kernel/sync/locked_by.rs b/rust/kernel/sync/locked_by.rs new file mode 100644 index 000000000000..b17ee5cd98f3 --- /dev/null +++ b/rust/kernel/sync/locked_by.rs @@ -0,0 +1,156 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! A wrapper for data protected by a lock that does not wrap it. + +use super::{lock::Backend, lock::Lock}; +use crate::build_assert; +use core::{cell::UnsafeCell, mem::size_of, ptr}; + +/// Allows access to some data to be serialised by a lock that does not wrap it. +/// +/// In most cases, data protected by a lock is wrapped by the appropriate lock type, e.g., +/// [`super::Mutex`] or [`super::SpinLock`]. [`LockedBy`] is meant for cases when this is not +/// possible. For example, if a container has a lock and some data in the contained elements needs +/// to be protected by the same lock. +/// +/// [`LockedBy`] wraps the data in lieu of another locking primitive, and only allows access to it +/// when the caller shows evidence that the 'external' lock is locked. It panics if the evidence +/// refers to the wrong instance of the lock. +/// +/// # Examples +/// +/// The following is an example for illustrative purposes: `InnerDirectory::bytes_used` is an +/// aggregate of all `InnerFile::bytes_used` and must be kept consistent; so we wrap `InnerFile` in +/// a `LockedBy` so that it shares a lock with `InnerDirectory`. This allows us to enforce at +/// compile-time that access to `InnerFile` is only granted when an `InnerDirectory` is also +/// locked; we enforce at run time that the right `InnerDirectory` is locked. +/// +/// ``` +/// use kernel::sync::{LockedBy, Mutex}; +/// +/// struct InnerFile { +/// bytes_used: u64, +/// } +/// +/// struct File { +/// _ino: u32, +/// inner: LockedBy, +/// } +/// +/// struct InnerDirectory { +/// /// The sum of the bytes used by all files. +/// bytes_used: u64, +/// _files: Vec, +/// } +/// +/// struct Directory { +/// _ino: u32, +/// inner: Mutex, +/// } +/// +/// /// Prints `bytes_used` from both the directory and file. +/// fn print_bytes_used(dir: &Directory, file: &File) { +/// let guard = dir.inner.lock(); +/// let inner_file = file.inner.access(&guard); +/// pr_info!("{} {}", guard.bytes_used, inner_file.bytes_used); +/// } +/// +/// /// Increments `bytes_used` for both the directory and file. +/// fn inc_bytes_used(dir: &Directory, file: &File) { +/// let mut guard = dir.inner.lock(); +/// guard.bytes_used += 10; +/// +/// let file_inner = file.inner.access_mut(&mut guard); +/// file_inner.bytes_used += 10; +/// } +/// +/// /// Creates a new file. +/// fn new_file(ino: u32, dir: &Directory) -> File { +/// File { +/// _ino: ino, +/// inner: LockedBy::new(&dir.inner, InnerFile { bytes_used: 0 }), +/// } +/// } +/// ``` +pub struct LockedBy { + owner: *const U, + data: UnsafeCell, +} + +// SAFETY: `LockedBy` can be transferred across thread boundaries iff the data it protects can. +unsafe impl Send for LockedBy {} + +// SAFETY: `LockedBy` serialises the interior mutability it provides, so it is `Sync` as long as the +// data it protects is `Send`. +unsafe impl Sync for LockedBy {} + +impl LockedBy { + /// Constructs a new instance of [`LockedBy`]. + /// + /// It stores a raw pointer to the owner that is never dereferenced. It is only used to ensure + /// that the right owner is being used to access the protected data. If the owner is freed, the + /// data becomes inaccessible; if another instance of the owner is allocated *on the same + /// memory location*, the data becomes accessible again: none of this affects memory safety + /// because in any case at most one thread (or CPU) can access the protected data at a time. + pub fn new(owner: &Lock, data: T) -> Self { + build_assert!( + size_of::>() > 0, + "The lock type cannot be a ZST because it may be impossible to distinguish instances" + ); + Self { + owner: owner.data.get(), + data: UnsafeCell::new(data), + } + } +} + +impl LockedBy { + /// Returns a reference to the protected data when the caller provides evidence (via a + /// reference) that the owner is locked. + /// + /// `U` cannot be a zero-sized type (ZST) because there are ways to get an `&U` that matches + /// the data protected by the lock without actually holding it. + /// + /// # Panics + /// + /// Panics if `owner` is different from the data protected by the lock used in + /// [`new`](LockedBy::new). + pub fn access<'a>(&'a self, owner: &'a U) -> &'a T { + build_assert!( + size_of::() > 0, + "`U` cannot be a ZST because `owner` wouldn't be unique" + ); + if !ptr::eq(owner, self.owner) { + panic!("mismatched owners"); + } + + // SAFETY: `owner` is evidence that the owner is locked. + unsafe { &*self.data.get() } + } + + /// Returns a mutable reference to the protected data when the caller provides evidence (via a + /// mutable owner) that the owner is locked mutably. + /// + /// `U` cannot be a zero-sized type (ZST) because there are ways to get an `&mut U` that + /// matches the data protected by the lock without actually holding it. + /// + /// Showing a mutable reference to the owner is sufficient because we know no other references + /// can exist to it. + /// + /// # Panics + /// + /// Panics if `owner` is different from the data protected by the lock used in + /// [`new`](LockedBy::new). + pub fn access_mut<'a>(&'a self, owner: &'a mut U) -> &'a mut T { + build_assert!( + size_of::() > 0, + "`U` cannot be a ZST because `owner` wouldn't be unique" + ); + if !ptr::eq(owner, self.owner) { + panic!("mismatched owners"); + } + + // SAFETY: `owner` is evidence that there is only one reference to the owner. + unsafe { &mut *self.data.get() } + } +} -- cgit v1.2.3 From e32cca32c3d452a277884502b9155f3325caf80e Mon Sep 17 00:00:00 2001 From: Wedson Almeida Filho Date: Mon, 27 Mar 2023 15:43:08 -0300 Subject: rust: lock: add `Guard::do_unlocked` It releases the lock, executes some function provided by the caller, then reacquires the lock. This is preparation for the implementation of condvars, which will sleep after between unlocking and relocking. We need an explicit `relock` method for primitives like `SpinLock` that have an irqsave variant: we use the guard state to determine if the lock was originally acquired with the regular `lock` function or `lock_irqsave`. Reviewed-by: Martin Rodriguez Reboredo Signed-off-by: Wedson Almeida Filho Link: https://lore.kernel.org/rust-for-linux/20230412121431.41627-1-wedsonaf@gmail.com/ [ Removed the irqsave bits as discussed. ] Signed-off-by: Miguel Ojeda --- rust/kernel/sync/lock.rs | 29 ++++++++++++++++++++++++++++- rust/kernel/sync/lock/spinlock.rs | 3 ++- 2 files changed, 30 insertions(+), 2 deletions(-) (limited to 'rust') diff --git a/rust/kernel/sync/lock.rs b/rust/kernel/sync/lock.rs index 46e3328b67a6..802465d1fa54 100644 --- a/rust/kernel/sync/lock.rs +++ b/rust/kernel/sync/lock.rs @@ -6,7 +6,7 @@ //! spinlocks, raw spinlocks) to be provided with minimal effort. use super::LockClassKey; -use crate::{bindings, init::PinInit, pin_init, str::CStr, types::Opaque}; +use crate::{bindings, init::PinInit, pin_init, str::CStr, types::Opaque, types::ScopeGuard}; use core::{cell::UnsafeCell, marker::PhantomData, marker::PhantomPinned}; use macros::pin_data; @@ -22,6 +22,8 @@ pub mod spinlock; /// /// - Implementers must ensure that only one thread/CPU may access the protected data once the lock /// is owned, that is, between calls to `lock` and `unlock`. +/// - Implementers must also ensure that `relock` uses the same locking method as the original +/// lock operation. pub unsafe trait Backend { /// The state required by the lock. type State; @@ -55,6 +57,17 @@ pub unsafe trait Backend { /// /// It must only be called by the current owner of the lock. unsafe fn unlock(ptr: *mut Self::State, guard_state: &Self::GuardState); + + /// Reacquires the lock, making the caller its owner. + /// + /// # Safety + /// + /// Callers must ensure that `guard_state` comes from a previous call to [`Backend::lock`] (or + /// variant) that has been unlocked with [`Backend::unlock`] and will be relocked now. + unsafe fn relock(ptr: *mut Self::State, guard_state: &mut Self::GuardState) { + // SAFETY: The safety requirements ensure that the lock is initialised. + *guard_state = unsafe { Self::lock(ptr) }; + } } /// A mutual exclusion primitive. @@ -126,6 +139,20 @@ pub struct Guard<'a, T: ?Sized, B: Backend> { // SAFETY: `Guard` is sync when the data protected by the lock is also sync. unsafe impl Sync for Guard<'_, T, B> {} +impl Guard<'_, T, B> { + #[allow(dead_code)] + pub(crate) fn do_unlocked(&mut self, cb: impl FnOnce()) { + // SAFETY: The caller owns the lock, so it is safe to unlock it. + unsafe { B::unlock(self.lock.state.get(), &self.state) }; + + // SAFETY: The lock was just unlocked above and is being relocked now. + let _relock = + ScopeGuard::new(|| unsafe { B::relock(self.lock.state.get(), &mut self.state) }); + + cb(); + } +} + impl core::ops::Deref for Guard<'_, T, B> { type Target = T; diff --git a/rust/kernel/sync/lock/spinlock.rs b/rust/kernel/sync/lock/spinlock.rs index a52d20fc9755..979b56464a4e 100644 --- a/rust/kernel/sync/lock/spinlock.rs +++ b/rust/kernel/sync/lock/spinlock.rs @@ -87,7 +87,8 @@ pub type SpinLock = super::Lock; /// A kernel `spinlock_t` lock backend. pub struct SpinLockBackend; -// SAFETY: The underlying kernel `spinlock_t` object ensures mutual exclusion. +// SAFETY: The underlying kernel `spinlock_t` object ensures mutual exclusion. `relock` uses the +// default implementation that always calls the same locking method. unsafe impl super::Backend for SpinLockBackend { type State = bindings::spinlock_t; type GuardState = (); -- cgit v1.2.3 From 19096bce815716cf93fc1ef3965629c3affa26f1 Mon Sep 17 00:00:00 2001 From: Wedson Almeida Filho Date: Sun, 26 Mar 2023 00:57:38 -0300 Subject: rust: sync: introduce `CondVar` This is the traditional condition variable or monitor synchronisation primitive. It is implemented with C's `wait_queue_head_t`. It allows users to release a lock and go to sleep while guaranteeing that notifications won't be missed. This is achieved by enqueuing a wait entry before releasing the lock. Cc: Peter Zijlstra Cc: Ingo Molnar Cc: Will Deacon Cc: Waiman Long Reviewed-by: Martin Rodriguez Reboredo Signed-off-by: Wedson Almeida Filho Reviewed-by: Alice Ryhl Link: https://lore.kernel.org/r/20230411054543.21278-12-wedsonaf@gmail.com Signed-off-by: Miguel Ojeda --- rust/bindings/bindings_helper.h | 1 + rust/helpers.c | 7 ++ rust/kernel/sync.rs | 2 + rust/kernel/sync/condvar.rs | 174 ++++++++++++++++++++++++++++++++++++++++ rust/kernel/sync/lock.rs | 1 - 5 files changed, 184 insertions(+), 1 deletion(-) create mode 100644 rust/kernel/sync/condvar.rs (limited to 'rust') diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helper.h index 03656a44a83f..50e7a76d5455 100644 --- a/rust/bindings/bindings_helper.h +++ b/rust/bindings/bindings_helper.h @@ -8,6 +8,7 @@ #include #include +#include #include /* `bindgen` gets confused at certain things. */ diff --git a/rust/helpers.c b/rust/helpers.c index 2cb7b82053d8..81e80261d597 100644 --- a/rust/helpers.c +++ b/rust/helpers.c @@ -25,6 +25,7 @@ #include #include #include +#include __noreturn void rust_helper_BUG(void) { @@ -61,6 +62,12 @@ void rust_helper_spin_unlock(spinlock_t *lock) } EXPORT_SYMBOL_GPL(rust_helper_spin_unlock); +void rust_helper_init_wait(struct wait_queue_entry *wq_entry) +{ + init_wait(wq_entry); +} +EXPORT_SYMBOL_GPL(rust_helper_init_wait); + int rust_helper_signal_pending(struct task_struct *t) { return signal_pending(t); diff --git a/rust/kernel/sync.rs b/rust/kernel/sync.rs index 5393b0d76619..d219ee518eff 100644 --- a/rust/kernel/sync.rs +++ b/rust/kernel/sync.rs @@ -8,10 +8,12 @@ use crate::types::Opaque; mod arc; +mod condvar; pub mod lock; mod locked_by; pub use arc::{Arc, ArcBorrow, UniqueArc}; +pub use condvar::CondVar; pub use lock::{mutex::Mutex, spinlock::SpinLock}; pub use locked_by::LockedBy; diff --git a/rust/kernel/sync/condvar.rs b/rust/kernel/sync/condvar.rs new file mode 100644 index 000000000000..ed353399c4e5 --- /dev/null +++ b/rust/kernel/sync/condvar.rs @@ -0,0 +1,174 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! A condition variable. +//! +//! This module allows Rust code to use the kernel's [`struct wait_queue_head`] as a condition +//! variable. + +use super::{lock::Backend, lock::Guard, LockClassKey}; +use crate::{bindings, init::PinInit, pin_init, str::CStr, types::Opaque}; +use core::marker::PhantomPinned; +use macros::pin_data; + +/// Creates a [`CondVar`] initialiser with the given name and a newly-created lock class. +#[macro_export] +macro_rules! new_condvar { + ($($name:literal)?) => { + $crate::sync::CondVar::new($crate::optional_name!($($name)?), $crate::static_lock_class!()) + }; +} + +/// A conditional variable. +/// +/// Exposes the kernel's [`struct wait_queue_head`] as a condition variable. It allows the caller to +/// atomically release the given lock and go to sleep. It reacquires the lock when it wakes up. And +/// it wakes up when notified by another thread (via [`CondVar::notify_one`] or +/// [`CondVar::notify_all`]) or because the thread received a signal. It may also wake up +/// spuriously. +/// +/// Instances of [`CondVar`] need a lock class and to be pinned. The recommended way to create such +/// instances is with the [`pin_init`](crate::pin_init) and [`new_condvar`] macros. +/// +/// # Examples +/// +/// The following is an example of using a condvar with a mutex: +/// +/// ``` +/// use kernel::sync::{CondVar, Mutex}; +/// use kernel::{new_condvar, new_mutex}; +/// +/// #[pin_data] +/// pub struct Example { +/// #[pin] +/// value: Mutex, +/// +/// #[pin] +/// value_changed: CondVar, +/// } +/// +/// /// Waits for `e.value` to become `v`. +/// fn wait_for_value(e: &Example, v: u32) { +/// let mut guard = e.value.lock(); +/// while *guard != v { +/// e.value_changed.wait_uninterruptible(&mut guard); +/// } +/// } +/// +/// /// Increments `e.value` and notifies all potential waiters. +/// fn increment(e: &Example) { +/// *e.value.lock() += 1; +/// e.value_changed.notify_all(); +/// } +/// +/// /// Allocates a new boxed `Example`. +/// fn new_example() -> Result>> { +/// Box::pin_init(pin_init!(Example { +/// value <- new_mutex!(0), +/// value_changed <- new_condvar!(), +/// })) +/// } +/// ``` +/// +/// [`struct wait_queue_head`]: ../../../include/linux/wait.h +#[pin_data] +pub struct CondVar { + #[pin] + pub(crate) wait_list: Opaque, + + /// A condvar needs to be pinned because it contains a [`struct list_head`] that is + /// self-referential, so it cannot be safely moved once it is initialised. + #[pin] + _pin: PhantomPinned, +} + +// SAFETY: `CondVar` only uses a `struct wait_queue_head`, which is safe to use on any thread. +#[allow(clippy::non_send_fields_in_send_ty)] +unsafe impl Send for CondVar {} + +// SAFETY: `CondVar` only uses a `struct wait_queue_head`, which is safe to use on multiple threads +// concurrently. +unsafe impl Sync for CondVar {} + +impl CondVar { + /// Constructs a new condvar initialiser. + #[allow(clippy::new_ret_no_self)] + pub fn new(name: &'static CStr, key: &'static LockClassKey) -> impl PinInit { + pin_init!(Self { + _pin: PhantomPinned, + // SAFETY: `slot` is valid while the closure is called and both `name` and `key` have + // static lifetimes so they live indefinitely. + wait_list <- Opaque::ffi_init(|slot| unsafe { + bindings::__init_waitqueue_head(slot, name.as_char_ptr(), key.as_ptr()) + }), + }) + } + + fn wait_internal(&self, wait_state: u32, guard: &mut Guard<'_, T, B>) { + let wait = Opaque::::uninit(); + + // SAFETY: `wait` points to valid memory. + unsafe { bindings::init_wait(wait.get()) }; + + // SAFETY: Both `wait` and `wait_list` point to valid memory. + unsafe { + bindings::prepare_to_wait_exclusive(self.wait_list.get(), wait.get(), wait_state as _) + }; + + // SAFETY: No arguments, switches to another thread. + guard.do_unlocked(|| unsafe { bindings::schedule() }); + + // SAFETY: Both `wait` and `wait_list` point to valid memory. + unsafe { bindings::finish_wait(self.wait_list.get(), wait.get()) }; + } + + /// Releases the lock and waits for a notification in interruptible mode. + /// + /// Atomically releases the given lock (whose ownership is proven by the guard) and puts the + /// thread to sleep, reacquiring the lock on wake up. It wakes up when notified by + /// [`CondVar::notify_one`] or [`CondVar::notify_all`], or when the thread receives a signal. + /// It may also wake up spuriously. + /// + /// Returns whether there is a signal pending. + #[must_use = "wait returns if a signal is pending, so the caller must check the return value"] + pub fn wait(&self, guard: &mut Guard<'_, T, B>) -> bool { + self.wait_internal(bindings::TASK_INTERRUPTIBLE, guard); + crate::current!().signal_pending() + } + + /// Releases the lock and waits for a notification in uninterruptible mode. + /// + /// Similar to [`CondVar::wait`], except that the wait is not interruptible. That is, the + /// thread won't wake up due to signals. It may, however, wake up supirously. + pub fn wait_uninterruptible(&self, guard: &mut Guard<'_, T, B>) { + self.wait_internal(bindings::TASK_UNINTERRUPTIBLE, guard) + } + + /// Calls the kernel function to notify the appropriate number of threads with the given flags. + fn notify(&self, count: i32, flags: u32) { + // SAFETY: `wait_list` points to valid memory. + unsafe { + bindings::__wake_up( + self.wait_list.get(), + bindings::TASK_NORMAL, + count, + flags as _, + ) + }; + } + + /// Wakes a single waiter up, if any. + /// + /// This is not 'sticky' in the sense that if no thread is waiting, the notification is lost + /// completely (as opposed to automatically waking up the next waiter). + pub fn notify_one(&self) { + self.notify(1, 0); + } + + /// Wakes all waiters up, if any. + /// + /// This is not 'sticky' in the sense that if no thread is waiting, the notification is lost + /// completely (as opposed to automatically waking up the next waiter). + pub fn notify_all(&self) { + self.notify(0, 0); + } +} diff --git a/rust/kernel/sync/lock.rs b/rust/kernel/sync/lock.rs index 802465d1fa54..a2216325632d 100644 --- a/rust/kernel/sync/lock.rs +++ b/rust/kernel/sync/lock.rs @@ -140,7 +140,6 @@ pub struct Guard<'a, T: ?Sized, B: Backend> { unsafe impl Sync for Guard<'_, T, B> {} impl Guard<'_, T, B> { - #[allow(dead_code)] pub(crate) fn do_unlocked(&mut self, cb: impl FnOnce()) { // SAFETY: The caller owns the lock, so it is safe to unlock it. unsafe { B::unlock(self.lock.state.get(), &self.state) }; -- cgit v1.2.3 From 4e1746656839ab1e88d76eec4d2fa0b41d585604 Mon Sep 17 00:00:00 2001 From: Asahi Lina Date: Mon, 3 Apr 2023 18:33:52 +0900 Subject: rust: uapi: Add UAPI crate This crate mirrors the `bindings` crate, but will contain only UAPI bindings. Unlike the bindings crate, drivers may directly use this crate if they have to interface with userspace. Initially, just bind the generic ioctl stuff. In the future, we would also like to add additional checks to ensure that all types exposed by this crate satisfy UAPI-safety guarantees (that is, they are safely castable to/from a "bag of bits"). [ Miguel: added support for the `rustdoc` and `rusttest` targets, since otherwise they fail, and we want to keep them working. ] Reviewed-by: Martin Rodriguez Reboredo Signed-off-by: Asahi Lina Link: https://lore.kernel.org/r/20230329-rust-uapi-v2-1-bca5fb4d4a12@asahilina.net Signed-off-by: Miguel Ojeda --- rust/.gitignore | 1 + rust/Makefile | 28 +++++++++++++++++++++++----- rust/kernel/lib.rs | 1 + rust/uapi/lib.rs | 27 +++++++++++++++++++++++++++ rust/uapi/uapi_helper.h | 9 +++++++++ 5 files changed, 61 insertions(+), 5 deletions(-) create mode 100644 rust/uapi/lib.rs create mode 100644 rust/uapi/uapi_helper.h (limited to 'rust') diff --git a/rust/.gitignore b/rust/.gitignore index 168cb26a31b9..21552992b401 100644 --- a/rust/.gitignore +++ b/rust/.gitignore @@ -2,6 +2,7 @@ bindings_generated.rs bindings_helpers_generated.rs +uapi_generated.rs exports_*_generated.h doc/ test/ diff --git a/rust/Makefile b/rust/Makefile index f88d108fbef0..04bb52e88331 100644 --- a/rust/Makefile +++ b/rust/Makefile @@ -16,6 +16,9 @@ obj-$(CONFIG_RUST) += alloc.o bindings.o kernel.o always-$(CONFIG_RUST) += exports_alloc_generated.h exports_bindings_generated.h \ exports_kernel_generated.h +always-$(CONFIG_RUST) += uapi/uapi_generated.rs +obj-$(CONFIG_RUST) += uapi.o + ifdef CONFIG_RUST_BUILD_ASSERT_ALLOW obj-$(CONFIG_RUST) += build_error.o else @@ -113,7 +116,7 @@ rustdoc-alloc: $(src)/alloc/lib.rs rustdoc-core rustdoc-compiler_builtins FORCE rustdoc-kernel: private rustc_target_flags = --extern alloc \ --extern build_error --extern macros=$(objtree)/$(obj)/libmacros.so \ - --extern bindings + --extern bindings --extern uapi rustdoc-kernel: $(src)/kernel/lib.rs rustdoc-core rustdoc-macros \ rustdoc-compiler_builtins rustdoc-alloc $(obj)/libmacros.so \ $(obj)/bindings.o FORCE @@ -141,6 +144,9 @@ rusttestlib-macros: $(src)/macros/lib.rs rusttest-prepare FORCE rusttestlib-bindings: $(src)/bindings/lib.rs rusttest-prepare FORCE $(call if_changed,rustc_test_library) +rusttestlib-uapi: $(src)/uapi/lib.rs rusttest-prepare FORCE + $(call if_changed,rustc_test_library) + quiet_cmd_rustdoc_test = RUSTDOC T $< cmd_rustdoc_test = \ OBJTREE=$(abspath $(objtree)) \ @@ -223,9 +229,10 @@ rusttest-macros: $(src)/macros/lib.rs rusttest-prepare FORCE $(call if_changed,rustdoc_test) rusttest-kernel: private rustc_target_flags = --extern alloc \ - --extern build_error --extern macros --extern bindings + --extern build_error --extern macros --extern bindings --extern uapi rusttest-kernel: $(src)/kernel/lib.rs rusttest-prepare \ - rusttestlib-build_error rusttestlib-macros rusttestlib-bindings FORCE + rusttestlib-build_error rusttestlib-macros rusttestlib-bindings \ + rusttestlib-uapi FORCE $(call if_changed,rustc_test) $(call if_changed,rustc_test_library) @@ -288,6 +295,12 @@ $(obj)/bindings/bindings_generated.rs: $(src)/bindings/bindings_helper.h \ $(src)/bindgen_parameters FORCE $(call if_changed_dep,bindgen) +$(obj)/uapi/uapi_generated.rs: private bindgen_target_flags = \ + $(shell grep -v '^#\|^$$' $(srctree)/$(src)/bindgen_parameters) +$(obj)/uapi/uapi_generated.rs: $(src)/uapi/uapi_helper.h \ + $(src)/bindgen_parameters FORCE + $(call if_changed_dep,bindgen) + # See `CFLAGS_REMOVE_helpers.o` above. In addition, Clang on C does not warn # with `-Wmissing-declarations` (unlike GCC), so it is not strictly needed here # given it is `libclang`; but for consistency, future Clang changes and/or @@ -388,10 +401,15 @@ $(obj)/bindings.o: $(src)/bindings/lib.rs \ $(obj)/bindings/bindings_helpers_generated.rs FORCE $(call if_changed_dep,rustc_library) +$(obj)/uapi.o: $(src)/uapi/lib.rs \ + $(obj)/compiler_builtins.o \ + $(obj)/uapi/uapi_generated.rs FORCE + $(call if_changed_dep,rustc_library) + $(obj)/kernel.o: private rustc_target_flags = --extern alloc \ - --extern build_error --extern macros --extern bindings + --extern build_error --extern macros --extern bindings --extern uapi $(obj)/kernel.o: $(src)/kernel/lib.rs $(obj)/alloc.o $(obj)/build_error.o \ - $(obj)/libmacros.so $(obj)/bindings.o FORCE + $(obj)/libmacros.so $(obj)/bindings.o $(obj)/uapi.o FORCE $(call if_changed_dep,rustc_library) endif # CONFIG_RUST diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs index ee27e10da479..dd3b0d69fdd1 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -50,6 +50,7 @@ pub mod types; #[doc(hidden)] pub use bindings; pub use macros; +pub use uapi; #[doc(hidden)] pub use build_error::build_error; diff --git a/rust/uapi/lib.rs b/rust/uapi/lib.rs new file mode 100644 index 000000000000..29f69f3a52de --- /dev/null +++ b/rust/uapi/lib.rs @@ -0,0 +1,27 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! UAPI Bindings. +//! +//! Contains the bindings generated by `bindgen` for UAPI interfaces. +//! +//! This crate may be used directly by drivers that need to interact with +//! userspace APIs. + +#![no_std] +#![feature(core_ffi_c)] +// See . +#![cfg_attr(test, allow(deref_nullptr))] +#![cfg_attr(test, allow(unaligned_references))] +#![cfg_attr(test, allow(unsafe_op_in_unsafe_fn))] +#![allow( + clippy::all, + missing_docs, + non_camel_case_types, + non_upper_case_globals, + non_snake_case, + improper_ctypes, + unreachable_pub, + unsafe_op_in_unsafe_fn +)] + +include!(concat!(env!("OBJTREE"), "/rust/uapi/uapi_generated.rs")); diff --git a/rust/uapi/uapi_helper.h b/rust/uapi/uapi_helper.h new file mode 100644 index 000000000000..301f5207f023 --- /dev/null +++ b/rust/uapi/uapi_helper.h @@ -0,0 +1,9 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Header that contains the headers for which Rust UAPI bindings + * will be automatically generated by `bindgen`. + * + * Sorted alphabetically. + */ + +#include -- cgit v1.2.3 From ea76e08f4d901a450619831a255e9e0a4c0ed162 Mon Sep 17 00:00:00 2001 From: Asahi Lina Date: Mon, 3 Apr 2023 18:33:53 +0900 Subject: rust: ioctl: Add ioctl number manipulation functions Add simple 1:1 wrappers of the C ioctl number manipulation functions. Since these are macros we cannot bindgen them directly, and since they should be usable in const context we cannot use helper wrappers, so we'll have to reimplement them in Rust. Thankfully, the C headers do declare defines for the relevant bitfield positions, so we don't need to duplicate that. Signed-off-by: Asahi Lina Link: https://lore.kernel.org/r/20230329-rust-uapi-v2-2-bca5fb4d4a12@asahilina.net [ Moved the `#![allow(non_snake_case)]` to the usual place. ] Signed-off-by: Miguel Ojeda --- rust/kernel/ioctl.rs | 72 ++++++++++++++++++++++++++++++++++++++++++++++++++++ rust/kernel/lib.rs | 1 + 2 files changed, 73 insertions(+) create mode 100644 rust/kernel/ioctl.rs (limited to 'rust') diff --git a/rust/kernel/ioctl.rs b/rust/kernel/ioctl.rs new file mode 100644 index 000000000000..c49e1a8d3fd0 --- /dev/null +++ b/rust/kernel/ioctl.rs @@ -0,0 +1,72 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! ioctl() number definitions +//! +//! C header: [`include/asm-generic/ioctl.h`](../../../../include/asm-generic/ioctl.h) + +#![allow(non_snake_case)] + +use crate::build_assert; + +/// Build an ioctl number, analogous to the C macro of the same name. +#[inline(always)] +const fn _IOC(dir: u32, ty: u32, nr: u32, size: usize) -> u32 { + build_assert!(dir <= uapi::_IOC_DIRMASK); + build_assert!(ty <= uapi::_IOC_TYPEMASK); + build_assert!(nr <= uapi::_IOC_NRMASK); + build_assert!(size <= (uapi::_IOC_SIZEMASK as usize)); + + (dir << uapi::_IOC_DIRSHIFT) + | (ty << uapi::_IOC_TYPESHIFT) + | (nr << uapi::_IOC_NRSHIFT) + | ((size as u32) << uapi::_IOC_SIZESHIFT) +} + +/// Build an ioctl number for an argumentless ioctl. +#[inline(always)] +pub const fn _IO(ty: u32, nr: u32) -> u32 { + _IOC(uapi::_IOC_NONE, ty, nr, 0) +} + +/// Build an ioctl number for an read-only ioctl. +#[inline(always)] +pub const fn _IOR(ty: u32, nr: u32) -> u32 { + _IOC(uapi::_IOC_READ, ty, nr, core::mem::size_of::()) +} + +/// Build an ioctl number for an write-only ioctl. +#[inline(always)] +pub const fn _IOW(ty: u32, nr: u32) -> u32 { + _IOC(uapi::_IOC_WRITE, ty, nr, core::mem::size_of::()) +} + +/// Build an ioctl number for a read-write ioctl. +#[inline(always)] +pub const fn _IOWR(ty: u32, nr: u32) -> u32 { + _IOC( + uapi::_IOC_READ | uapi::_IOC_WRITE, + ty, + nr, + core::mem::size_of::(), + ) +} + +/// Get the ioctl direction from an ioctl number. +pub const fn _IOC_DIR(nr: u32) -> u32 { + (nr >> uapi::_IOC_DIRSHIFT) & uapi::_IOC_DIRMASK +} + +/// Get the ioctl type from an ioctl number. +pub const fn _IOC_TYPE(nr: u32) -> u32 { + (nr >> uapi::_IOC_TYPESHIFT) & uapi::_IOC_TYPEMASK +} + +/// Get the ioctl number from an ioctl number. +pub const fn _IOC_NR(nr: u32) -> u32 { + (nr >> uapi::_IOC_NRSHIFT) & uapi::_IOC_NRMASK +} + +/// Get the ioctl size from an ioctl number. +pub const fn _IOC_SIZE(nr: u32) -> usize { + ((nr >> uapi::_IOC_SIZESHIFT) & uapi::_IOC_SIZEMASK) as usize +} diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs index dd3b0d69fdd1..676995d4e460 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -37,6 +37,7 @@ mod allocator; mod build_assert; pub mod error; pub mod init; +pub mod ioctl; pub mod prelude; pub mod print; mod static_assert; -- cgit v1.2.3