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* entry: Respect changes to system call number by trace_sys_enter()André Rösti2024-03-121-1/+7
| | | | | | | | | | | | | | | | | | | | When a probe is registered at the trace_sys_enter() tracepoint, and that probe changes the system call number, the old system call still gets executed. This worked correctly until commit b6ec41346103 ("core/entry: Report syscall correctly for trace and audit"), which removed the re-evaluation of the syscall number after the trace point. Restore the original semantics by re-evaluating the system call number after trace_sys_enter(). The performance impact of this re-evaluation is minimal because it only takes place when a trace point is active, and compared to the actual trace point overhead the read from a cache hot variable is negligible. Fixes: b6ec41346103 ("core/entry: Report syscall correctly for trace and audit") Signed-off-by: André Rösti <an.roesti@gmail.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/r/20240311211704.7262-1-an.roesti@gmail.com
* entry: Move syscall_enter_from_user_mode() to header fileSven Schnelle2023-12-211-31/+1
| | | | | | | | | | To allow inlining of syscall_enter_from_user_mode(), move it to entry-common.h. Signed-off-by: Sven Schnelle <svens@linux.ibm.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/r/20231218074520.1998026-4-svens@linux.ibm.com
* entry: Move enter_from_user_mode() to header fileSven Schnelle2023-12-211-23/+3
| | | | | | | | | | To allow inlining of enter_from_user_mode(), move it to entry-common.h. Signed-off-by: Sven Schnelle <svens@linux.ibm.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/r/20231218074520.1998026-3-svens@linux.ibm.com
* entry: Move exit to usermode functions to header fileSven Schnelle2023-12-211-43/+9
| | | | | | | | | | To allow inlining, move exit_to_user_mode() to entry-common.h. Signed-off-by: Sven Schnelle <svens@linux.ibm.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/r/20231218074520.1998026-2-svens@linux.ibm.com
* entry: Remove empty addr_limit_user_check()Mark Rutland2023-08-231-2/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | Back when set_fs() was a generic API for altering the address limit, addr_limit_user_check() was a safety measure to prevent userspace being able to issue syscalls with an unbound limit. With the the removal of set_fs() as a generic API, the last user of addr_limit_user_check() was removed in commit: b5a5a01d8e9a44ec ("arm64: uaccess: remove addr_limit_user_check()") ... as since that commit, no architecture defines TIF_FSCHECK, and hence addr_limit_user_check() always expands to nothing. Remove addr_limit_user_check(), updating the comment in exit_to_user_mode_prepare() to no longer refer to it. At the same time, the comment is reworded to be a little more generic so as to cover kmap_assert_nomap() in addition to lockdep_sys_exit(). No functional change. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/r/20230821163526.2319443-1-mark.rutland@arm.com
* ptrace: Provide set/get interface for syscall user dispatchGregory Price2023-04-161-0/+40
| | | | | | | | | | | | | | | The syscall user dispatch configuration can only be set by the task itself, but lacks a ptrace set/get interface which makes it impossible to implement checkpoint/restore for it. Add the required ptrace requests and the get/set functions in the syscall user dispatch code to make that possible. Signed-off-by: Gregory Price <gregory.price@memverge.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Oleg Nesterov <oleg@redhat.com> Link: https://lore.kernel.org/r/20230407171834.3558-4-gregory.price@memverge.com
* syscall_user_dispatch: Untag selector address before access_ok()Gregory Price2023-04-161-1/+10
| | | | | | | | | | | | | | | | | | | | | | | | | | | To support checkpoint/restart, ptrace must be able to set the selector of the tracee. The selector is a user pointer that may be subject to memory tagging extensions on some architectures (namely ARM MTE). access_ok() clears memory tags for tagged addresses if the current task has memory tagging enabled. This obviously fails when ptrace modifies the selector of a tracee when tracer and tracee do not have the same memory tagging enabled state. Solve this by untagging the selector address before handing it to access_ok(), like other ptrace functions which modify tracee pointers do. Obviously a tracer can set an invalid selector address for the tracee, but that's independent of tagging and a general capability of the tracer. Suggested-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Gregory Price <gregory.price@memverge.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Oleg Nesterov <oleg@redhat.com> Link: https://lore.kernel.org/all/ZCWXE04nLZ4pXEtM@arm.com/ Link: https://lore.kernel.org/r/20230407171834.3558-3-gregory.price@memverge.com
* syscall_user_dispatch: Split up set_syscall_user_dispatch()Gregory Price2023-04-161-8/+15
| | | | | | | | | | | | | | | | | syscall user dispatch configuration is not covered by checkpoint/restore. To prepare for ptrace access to the syscall user dispatch configuration, move the inner working of set_syscall_user_dispatch() into a helper function. Make the helper function task pointer based and let set_syscall_user_dispatch() invoke it with task=current. No functional change. Signed-off-by: Gregory Price <gregory.price@memverge.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Oleg Nesterov <oleg@redhat.com> Link: https://lore.kernel.org/r/20230407171834.3558-2-gregory.price@memverge.com
* entry/rcu: Check TIF_RESCHED _after_ delayed RCU wake-upFrederic Weisbecker2023-03-211-1/+2
| | | | | | | | | | | | | | | | | | | | | | | RCU sometimes needs to perform a delayed wake up for specific kthreads handling offloaded callbacks (RCU_NOCB). These wakeups are performed by timers and upon entry to idle (also to guest and to user on nohz_full). However the delayed wake-up on kernel exit is actually performed after the thread flags are fetched towards the fast path check for work to do on exit to user. As a result, and if there is no other pending work to do upon that kernel exit, the current task will resume to userspace with TIF_RESCHED set and the pending wake up ignored. Fix this with fetching the thread flags _after_ the delayed RCU-nocb kthread wake-up. Fixes: 47b8ff194c1f ("entry: Explicitly flush pending rcuog wakeup before last rescheduling point") Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/r/20230315194349.10798-3-joel@joelfernandes.org
* entry: Fix noinstr warning in __enter_from_user_mode()Josh Poimboeuf2023-03-211-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | __enter_from_user_mode() is triggering noinstr warnings with CONFIG_DEBUG_PREEMPT due to its call of preempt_count_add() via ct_state(). The preemption disable isn't needed as interrupts are already disabled. And the context_tracking_enabled() check in ct_state() also isn't needed as that's already being done by the CT_WARN_ON(). Just use __ct_state() instead. Fixes the following warnings: vmlinux.o: warning: objtool: enter_from_user_mode+0xba: call to preempt_count_add() leaves .noinstr.text section vmlinux.o: warning: objtool: syscall_enter_from_user_mode+0xf9: call to preempt_count_add() leaves .noinstr.text section vmlinux.o: warning: objtool: syscall_enter_from_user_mode_prepare+0xc7: call to preempt_count_add() leaves .noinstr.text section vmlinux.o: warning: objtool: irqentry_enter_from_user_mode+0xba: call to preempt_count_add() leaves .noinstr.text section Fixes: 171476775d32 ("context_tracking: Convert state to atomic_t") Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/r/d8955fa6d68dc955dda19baf13ae014ae27926f5.1677369694.git.jpoimboe@kernel.org
* entry: kmsan: introduce kmsan_unpoison_entry_regs()Alexander Potapenko2022-10-031-0/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | struct pt_regs passed into IRQ entry code is set up by uninstrumented asm functions, therefore KMSAN may not notice the registers are initialized. kmsan_unpoison_entry_regs() unpoisons the contents of struct pt_regs, preventing potential false positives. Unlike kmsan_unpoison_memory(), it can be called under kmsan_in_runtime(), which is often the case in IRQ entry code. Link: https://lkml.kernel.org/r/20220915150417.722975-41-glider@google.com Signed-off-by: Alexander Potapenko <glider@google.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Andrey Konovalov <andreyknvl@gmail.com> Cc: Andrey Konovalov <andreyknvl@google.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Borislav Petkov <bp@alien8.de> Cc: Christoph Hellwig <hch@lst.de> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Eric Biggers <ebiggers@google.com> Cc: Eric Biggers <ebiggers@kernel.org> Cc: Eric Dumazet <edumazet@google.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Herbert Xu <herbert@gondor.apana.org.au> Cc: Ilya Leoshkevich <iii@linux.ibm.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Kees Cook <keescook@chromium.org> Cc: Marco Elver <elver@google.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michael S. Tsirkin <mst@redhat.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Petr Mladek <pmladek@suse.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Vegard Nossum <vegard.nossum@oracle.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
* context_tracking: Take NMI eqs entrypoints over RCUFrederic Weisbecker2022-07-051-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | The RCU dynticks counter is going to be merged into the context tracking subsystem. Prepare with moving the NMI extended quiescent states entrypoints to context tracking. For now those are dumb redirection to existing RCU calls. Acked-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com> Cc: Uladzislau Rezki <uladzislau.rezki@sony.com> Cc: Joel Fernandes <joel@joelfernandes.org> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Nicolas Saenz Julienne <nsaenz@kernel.org> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Xiongfeng Wang <wangxiongfeng2@huawei.com> Cc: Yu Liao <liaoyu15@huawei.com> Cc: Phil Auld <pauld@redhat.com> Cc: Paul Gortmaker<paul.gortmaker@windriver.com> Cc: Alex Belits <abelits@marvell.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Reviewed-by: Nicolas Saenz Julienne <nsaenzju@redhat.com> Tested-by: Nicolas Saenz Julienne <nsaenzju@redhat.com>
* context_tracking: Take IRQ eqs entrypoints over RCUFrederic Weisbecker2022-07-051-6/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | The RCU dynticks counter is going to be merged into the context tracking subsystem. Prepare with moving the IRQ extended quiescent states entrypoints to context tracking. For now those are dumb redirection to existing RCU calls. [ paulmck: Apply Stephen Rothwell feedback from -next. ] [ paulmck: Apply Nathan Chancellor feedback. ] Acked-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com> Cc: Uladzislau Rezki <uladzislau.rezki@sony.com> Cc: Joel Fernandes <joel@joelfernandes.org> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Nicolas Saenz Julienne <nsaenz@kernel.org> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Xiongfeng Wang <wangxiongfeng2@huawei.com> Cc: Yu Liao <liaoyu15@huawei.com> Cc: Phil Auld <pauld@redhat.com> Cc: Paul Gortmaker<paul.gortmaker@windriver.com> Cc: Alex Belits <abelits@marvell.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Reviewed-by: Nicolas Saenz Julienne <nsaenzju@redhat.com> Tested-by: Nicolas Saenz Julienne <nsaenzju@redhat.com>
* Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvmLinus Torvalds2022-06-081-6/+0
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Pull KVM fixes from Paolo Bonzini: - syzkaller NULL pointer dereference - TDP MMU performance issue with disabling dirty logging - 5.14 regression with SVM TSC scaling - indefinite stall on applying live patches - unstable selftest - memory leak from wrong copy-and-paste - missed PV TLB flush when racing with emulation * tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: KVM: x86: do not report a vCPU as preempted outside instruction boundaries KVM: x86: do not set st->preempted when going back to user space KVM: SVM: fix tsc scaling cache logic KVM: selftests: Make hyperv_clock selftest more stable KVM: x86/MMU: Zap non-leaf SPTEs when disabling dirty logging x86: drop bogus "cc" clobber from __try_cmpxchg_user_asm() KVM: x86/mmu: Check every prev_roots in __kvm_mmu_free_obsolete_roots() entry/kvm: Exit to user mode when TIF_NOTIFY_SIGNAL is set KVM: Don't null dereference ops->destroy
| * entry/kvm: Exit to user mode when TIF_NOTIFY_SIGNAL is setSeth Forshee2022-06-071-6/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | A livepatch transition may stall indefinitely when a kvm vCPU is heavily loaded. To the host, the vCPU task is a user thread which is spending a very long time in the ioctl(KVM_RUN) syscall. During livepatch transition, set_notify_signal() will be called on such tasks to interrupt the syscall so that the task can be transitioned. This interrupts guest execution, but when xfer_to_guest_mode_work() sees that TIF_NOTIFY_SIGNAL is set but not TIF_SIGPENDING it concludes that an exit to user mode is unnecessary, and guest execution is resumed without transitioning the task for the livepatch. This handling of TIF_NOTIFY_SIGNAL is incorrect, as set_notify_signal() is expected to break tasks out of interruptible kernel loops and cause them to return to userspace. Change xfer_to_guest_mode_work() to handle TIF_NOTIFY_SIGNAL the same as TIF_SIGPENDING, signaling to the vCPU run loop that an exit to userpsace is needed. Any pending task_work will be run when get_signal() is called from exit_to_user_mode_loop(), so there is no longer any need to run task work from xfer_to_guest_mode_work(). Suggested-by: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Petr Mladek <pmladek@suse.com> Signed-off-by: Seth Forshee <sforshee@digitalocean.com> Message-Id: <20220504180840.2907296-1-sforshee@digitalocean.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
* | Merge tag 'locking-core-2022-05-23' of ↵Linus Torvalds2022-05-241-3/+3
|\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull locking updates from Ingo Molnar: - rwsem cleanups & optimizations/fixes: - Conditionally wake waiters in reader/writer slowpaths - Always try to wake waiters in out_nolock path - Add try_cmpxchg64() implementation, with arch optimizations - and use it to micro-optimize sched_clock_{local,remote}() - Various force-inlining fixes to address objdump instrumentation-check warnings - Add lock contention tracepoints: lock:contention_begin lock:contention_end - Misc smaller fixes & cleanups * tag 'locking-core-2022-05-23' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: sched/clock: Use try_cmpxchg64 in sched_clock_{local,remote} locking/atomic/x86: Introduce arch_try_cmpxchg64 locking/atomic: Add generic try_cmpxchg64 support futex: Remove a PREEMPT_RT_FULL reference. locking/qrwlock: Change "queue rwlock" to "queued rwlock" lockdep: Delete local_irq_enable_in_hardirq() locking/mutex: Make contention tracepoints more consistent wrt adaptive spinning locking: Apply contention tracepoints in the slow path locking: Add lock contention tracepoints locking/rwsem: Always try to wake waiters in out_nolock path locking/rwsem: Conditionally wake waiters in reader/writer slowpaths locking/rwsem: No need to check for handoff bit if wait queue empty lockdep: Fix -Wunused-parameter for _THIS_IP_ x86/mm: Force-inline __phys_addr_nodebug() x86/kvm/svm: Force-inline GHCB accessors task_stack, x86/cea: Force-inline stack helpers
| * | lockdep: Fix -Wunused-parameter for _THIS_IP_Nick Desaulniers2022-04-051-3/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | While looking into a bug related to the compiler's handling of addresses of labels, I noticed some uses of _THIS_IP_ seemed unused in lockdep. Drive by cleanup. -Wunused-parameter: kernel/locking/lockdep.c:1383:22: warning: unused parameter 'ip' kernel/locking/lockdep.c:4246:48: warning: unused parameter 'ip' kernel/locking/lockdep.c:4844:19: warning: unused parameter 'ip' Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Waiman Long <longman@redhat.com> Link: https://lore.kernel.org/r/20220314221909.2027027-1-ndesaulniers@google.com
* | | entry: Rename arch_check_user_regs() to arch_enter_from_user_mode()Sven Schnelle2022-05-091-1/+1
| |/ |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | arch_check_user_regs() is used at the moment to verify that struct pt_regs contains valid values when entering the kernel from userspace. s390 needs a place in the generic entry code to modify a cpu data structure when switching from userspace to kernel mode. As arch_check_user_regs() is exactly this, rename it to arch_enter_from_user_mode(). When entering the kernel from userspace, arch_check_user_regs() is used to verify that struct pt_regs contains valid values. Note that the NMI codepath doesn't call this function. s390 needs a place in the generic entry code to modify a cpu data structure when switching from userspace to kernel mode. As arch_check_user_regs() is exactly this, rename it to arch_enter_from_user_mode(). Signed-off-by: Sven Schnelle <svens@linux.ibm.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andy Lutomirski <luto@kernel.org> Link: https://lore.kernel.org/r/20220504062351.2954280-2-tmricht@linux.ibm.com Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
* | entry: Fix compile error in dynamic_irqentry_exit_cond_resched()Sven Schnelle2022-04-051-1/+1
|/ | | | | | | | | | | | | | | | kernel/entry/common.c: In function ‘dynamic_irqentry_exit_cond_resched’: kernel/entry/common.c:409:14: error: implicit declaration of function ‘static_key_unlikely’; did you mean ‘static_key_enable’? [-Werror=implicit-function-declaration] 409 | if (!static_key_unlikely(&sk_dynamic_irqentry_exit_cond_resched)) | ^~~~~~~~~~~~~~~~~~~ | static_key_enable static_key_unlikely() should be static_branch_unlikely(). Fixes: 99cf983cc8bca ("sched/preempt: Add PREEMPT_DYNAMIC using static keys") Signed-off-by: Sven Schnelle <svens@linux.ibm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Mark Rutland <mark.rutland@arm.com> Link: https://lore.kernel.org/r/20220330084328.1805665-1-svens@linux.ibm.com
* Revert "signal, x86: Delay calling signals in atomic on RT enabled kernels"Thomas Gleixner2022-03-311-14/+0
| | | | | | | | | | Revert commit bf9ad37dc8a. It needs to be better encapsulated and generalized. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
* Merge tag 'ptrace-cleanups-for-v5.18' of ↵Linus Torvalds2022-03-282-16/+12
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace Pull ptrace cleanups from Eric Biederman: "This set of changes removes tracehook.h, moves modification of all of the ptrace fields inside of siglock to remove races, adds a missing permission check to ptrace.c The removal of tracehook.h is quite significant as it has been a major source of confusion in recent years. Much of that confusion was around task_work and TIF_NOTIFY_SIGNAL (which I have now decoupled making the semantics clearer). For people who don't know tracehook.h is a vestiage of an attempt to implement uprobes like functionality that was never fully merged, and was later superseeded by uprobes when uprobes was merged. For many years now we have been removing what tracehook functionaly a little bit at a time. To the point where anything left in tracehook.h was some weird strange thing that was difficult to understand" * tag 'ptrace-cleanups-for-v5.18' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: ptrace: Remove duplicated include in ptrace.c ptrace: Check PTRACE_O_SUSPEND_SECCOMP permission on PTRACE_SEIZE ptrace: Return the signal to continue with from ptrace_stop ptrace: Move setting/clearing ptrace_message into ptrace_stop tracehook: Remove tracehook.h resume_user_mode: Move to resume_user_mode.h resume_user_mode: Remove #ifdef TIF_NOTIFY_RESUME in set_notify_resume signal: Move set_notify_signal and clear_notify_signal into sched/signal.h task_work: Decouple TIF_NOTIFY_SIGNAL and task_work task_work: Call tracehook_notify_signal from get_signal on all architectures task_work: Introduce task_work_pending task_work: Remove unnecessary include from posix_timers.h ptrace: Remove tracehook_signal_handler ptrace: Remove arch_syscall_{enter,exit}_tracehook ptrace: Create ptrace_report_syscall_{entry,exit} in ptrace.h ptrace/arm: Rename tracehook_report_syscall report_syscall ptrace: Move ptrace_report_syscall into ptrace.h
| * resume_user_mode: Move to resume_user_mode.hEric W. Biederman2022-03-102-3/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Move set_notify_resume and tracehook_notify_resume into resume_user_mode.h. While doing that rename tracehook_notify_resume to resume_user_mode_work. Update all of the places that included tracehook.h for these functions to include resume_user_mode.h instead. Update all of the callers of tracehook_notify_resume to call resume_user_mode_work. Reviewed-by: Kees Cook <keescook@chromium.org> Link: https://lkml.kernel.org/r/20220309162454.123006-12-ebiederm@xmission.com Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
| * task_work: Decouple TIF_NOTIFY_SIGNAL and task_workEric W. Biederman2022-03-101-2/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | There are a small handful of reasons besides pending signals that the kernel might want to break out of interruptible sleeps. The flag TIF_NOTIFY_SIGNAL and the helpers that set and clear TIF_NOTIFY_SIGNAL provide that the infrastructure for breaking out of interruptible sleeps and entering the return to user space slow path for those cases. Expand tracehook_notify_signal inline in it's callers and remove it, which makes clear that TIF_NOTIFY_SIGNAL and task_work are separate concepts. Update the comment on set_notify_signal to more accurately describe it's purpose. Reviewed-by: Kees Cook <keescook@chromium.org> Link: https://lkml.kernel.org/r/20220309162454.123006-9-ebiederm@xmission.com Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
| * task_work: Call tracehook_notify_signal from get_signal on all architecturesEric W. Biederman2022-03-102-11/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Always handle TIF_NOTIFY_SIGNAL in get_signal. With commit 35d0b389f3b2 ("task_work: unconditionally run task_work from get_signal()") always calling task_work_run all of the work of tracehook_notify_signal is already happening except clearing TIF_NOTIFY_SIGNAL. Factor clear_notify_signal out of tracehook_notify_signal and use it in get_signal so that get_signal only needs one call of task_work_run. To keep the semantics in sync update xfer_to_guest_mode_work (which does not call get_signal) to call tracehook_notify_signal if either _TIF_SIGPENDING or _TIF_NOTIFY_SIGNAL. Reviewed-by: Kees Cook <keescook@chromium.org> Link: https://lkml.kernel.org/r/20220309162454.123006-8-ebiederm@xmission.com Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
| * ptrace: Remove arch_syscall_{enter,exit}_tracehookEric W. Biederman2022-03-101-2/+2
| | | | | | | | | | | | | | | | | | | | These functions are alwasy one-to-one wrappers around ptrace_report_syscall_entry and ptrace_report_syscall_exit. So directly call the functions they are wrapping instead. Reviewed-by: Kees Cook <keescook@chromium.org> Link: https://lkml.kernel.org/r/20220309162454.123006-4-ebiederm@xmission.com Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
| * ptrace: Create ptrace_report_syscall_{entry,exit} in ptrace.hEric W. Biederman2022-03-101-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | Rename tracehook_report_syscall_{entry,exit} to ptrace_report_syscall_{entry,exit} and place them in ptrace.h There is no longer any generic tracehook infractructure so make these ptrace specific functions ptrace specific. Reviewed-by: Kees Cook <keescook@chromium.org> Link: https://lkml.kernel.org/r/20220309162454.123006-3-ebiederm@xmission.com Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
* | Merge tag 'sched-core-2022-03-22' of ↵Linus Torvalds2022-03-221-8/+15
|\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull scheduler updates from Ingo Molnar: - Cleanups for SCHED_DEADLINE - Tracing updates/fixes - CPU Accounting fixes - First wave of changes to optimize the overhead of the scheduler build, from the fast-headers tree - including placeholder *_api.h headers for later header split-ups. - Preempt-dynamic using static_branch() for ARM64 - Isolation housekeeping mask rework; preperatory for further changes - NUMA-balancing: deal with CPU-less nodes - NUMA-balancing: tune systems that have multiple LLC cache domains per node (eg. AMD) - Updates to RSEQ UAPI in preparation for glibc usage - Lots of RSEQ/selftests, for same - Add Suren as PSI co-maintainer * tag 'sched-core-2022-03-22' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (81 commits) sched/headers: ARM needs asm/paravirt_api_clock.h too sched/numa: Fix boot crash on arm64 systems headers/prep: Fix header to build standalone: <linux/psi.h> sched/headers: Only include <linux/entry-common.h> when CONFIG_GENERIC_ENTRY=y cgroup: Fix suspicious rcu_dereference_check() usage warning sched/preempt: Tell about PREEMPT_DYNAMIC on kernel headers sched/topology: Remove redundant variable and fix incorrect type in build_sched_domains sched/deadline,rt: Remove unused parameter from pick_next_[rt|dl]_entity() sched/deadline,rt: Remove unused functions for !CONFIG_SMP sched/deadline: Use __node_2_[pdl|dle]() and rb_first_cached() consistently sched/deadline: Merge dl_task_can_attach() and dl_cpu_busy() sched/deadline: Move bandwidth mgmt and reclaim functions into sched class source file sched/deadline: Remove unused def_dl_bandwidth sched/tracing: Report TASK_RTLOCK_WAIT tasks as TASK_UNINTERRUPTIBLE sched/tracing: Don't re-read p->state when emitting sched_switch event sched/rt: Plug rt_mutex_setprio() vs push_rt_task() race sched/cpuacct: Remove redundant RCU read lock sched/cpuacct: Optimize away RCU read lock sched/cpuacct: Fix charge percpu cpuusage sched/headers: Reorganize, clean up and optimize kernel/sched/sched.h dependencies ...
| * | sched/preempt: Add PREEMPT_DYNAMIC using static keysMark Rutland2022-02-191-0/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Where an architecture selects HAVE_STATIC_CALL but not HAVE_STATIC_CALL_INLINE, each static call has an out-of-line trampoline which will either branch to a callee or return to the caller. On such architectures, a number of constraints can conspire to make those trampolines more complicated and potentially less useful than we'd like. For example: * Hardware and software control flow integrity schemes can require the addition of "landing pad" instructions (e.g. `BTI` for arm64), which will also be present at the "real" callee. * Limited branch ranges can require that trampolines generate or load an address into a register and perform an indirect branch (or at least have a slow path that does so). This loses some of the benefits of having a direct branch. * Interaction with SW CFI schemes can be complicated and fragile, e.g. requiring that we can recognise idiomatic codegen and remove indirections understand, at least until clang proves more helpful mechanisms for dealing with this. For PREEMPT_DYNAMIC, we don't need the full power of static calls, as we really only need to enable/disable specific preemption functions. We can achieve the same effect without a number of the pain points above by using static keys to fold early returns into the preemption functions themselves rather than in an out-of-line trampoline, effectively inlining the trampoline into the start of the function. For arm64, this results in good code generation. For example, the dynamic_cond_resched() wrapper looks as follows when enabled. When disabled, the first `B` is replaced with a `NOP`, resulting in an early return. | <dynamic_cond_resched>: | bti c | b <dynamic_cond_resched+0x10> // or `nop` | mov w0, #0x0 | ret | mrs x0, sp_el0 | ldr x0, [x0, #8] | cbnz x0, <dynamic_cond_resched+0x8> | paciasp | stp x29, x30, [sp, #-16]! | mov x29, sp | bl <preempt_schedule_common> | mov w0, #0x1 | ldp x29, x30, [sp], #16 | autiasp | ret ... compared to the regular form of the function: | <__cond_resched>: | bti c | mrs x0, sp_el0 | ldr x1, [x0, #8] | cbz x1, <__cond_resched+0x18> | mov w0, #0x0 | ret | paciasp | stp x29, x30, [sp, #-16]! | mov x29, sp | bl <preempt_schedule_common> | mov w0, #0x1 | ldp x29, x30, [sp], #16 | autiasp | ret Any architecture which implements static keys should be able to use this to implement PREEMPT_DYNAMIC with similar cost to non-inlined static calls. Since this is likely to have greater overhead than (inlined) static calls, PREEMPT_DYNAMIC is only defaulted to enabled when HAVE_PREEMPT_DYNAMIC_CALL is selected. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Ard Biesheuvel <ardb@kernel.org> Acked-by: Frederic Weisbecker <frederic@kernel.org> Link: https://lore.kernel.org/r/20220214165216.2231574-6-mark.rutland@arm.com
| * | sched/preempt: Simplify irqentry_exit_cond_resched() callersMark Rutland2022-02-191-8/+4
| |/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently callers of irqentry_exit_cond_resched() need to be aware of whether the function should be indirected via a static call, leading to ugly ifdeffery in callers. Save them the hassle with a static inline wrapper that does the right thing. The raw_irqentry_exit_cond_resched() will also be useful in subsequent patches which will add conditional wrappers for preemption functions. Note: in arch/x86/entry/common.c, xen_pv_evtchn_do_upcall() always calls irqentry_exit_cond_resched() directly, even when PREEMPT_DYNAMIC is in use. I believe this is a latent bug (which this patch corrects), but I'm not entirely certain this wasn't deliberate. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Ard Biesheuvel <ardb@kernel.org> Acked-by: Frederic Weisbecker <frederic@kernel.org> Link: https://lore.kernel.org/r/20220214165216.2231574-4-mark.rutland@arm.com
* / signal, x86: Delay calling signals in atomic on RT enabled kernelsOleg Nesterov2022-03-041-0/+14
|/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | On x86_64 we must disable preemption before we enable interrupts for stack faults, int3 and debugging, because the current task is using a per CPU debug stack defined by the IST. If we schedule out, another task can come in and use the same stack and cause the stack to be corrupted and crash the kernel on return. When CONFIG_PREEMPT_RT is enabled, spinlock_t locks become sleeping, and one of these is the spin lock used in signal handling. Some of the debug code (int3) causes do_trap() to send a signal. This function calls a spinlock_t lock that has been converted to a sleeping lock. If this happens, the above issues with the corrupted stack is possible. Instead of calling the signal right away, for PREEMPT_RT and x86, the signal information is stored on the stacks task_struct and TIF_NOTIFY_RESUME is set. Then on exit of the trap, the signal resume code will send the signal when preemption is enabled. [ rostedt: Switched from #ifdef CONFIG_PREEMPT_RT to ARCH_RT_DELAYS_SIGNAL_SEND and added comments to the code. ] [bigeasy: Add on 32bit as per Yang Shi, minor rewording. ] [ tglx: Use a config option ] Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/r/Ygq5aBB/qMQw6aP5@linutronix.de
* entry: Snapshot thread flagsMark Rutland2021-12-012-4/+4
| | | | | | | | | | | | | | | | | | Some thread flags can be set remotely, and so even when IRQs are disabled, the flags can change under our feet. Generally this is unlikely to cause a problem in practice, but it is somewhat unsound, and KCSAN will legitimately warn that there is a data race. To avoid such issues, a snapshot of the flags has to be taken prior to using them. Some places already use READ_ONCE() for that, others do not. Convert them all to the new flag accessor helpers. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Paul E. McKenney <paulmck@kernel.org> Link: https://lore.kernel.org/r/20211129130653.2037928-3-mark.rutland@arm.com
* signal: Replace force_fatal_sig with force_exit_sig when in doubtEric W. Biederman2021-11-191-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Recently to prevent issues with SECCOMP_RET_KILL and similar signals being changed before they are delivered SA_IMMUTABLE was added. Unfortunately this broke debuggers[1][2] which reasonably expect to be able to trap synchronous SIGTRAP and SIGSEGV even when the target process is not configured to handle those signals. Add force_exit_sig and use it instead of force_fatal_sig where historically the code has directly called do_exit. This has the implementation benefits of going through the signal exit path (including generating core dumps) without the danger of allowing userspace to ignore or change these signals. This avoids userspace regressions as older kernels exited with do_exit which debuggers also can not intercept. In the future is should be possible to improve the quality of implementation of the kernel by changing some of these force_exit_sig calls to force_fatal_sig. That can be done where it matters on a case-by-case basis with careful analysis. Reported-by: Kyle Huey <me@kylehuey.com> Reported-by: kernel test robot <oliver.sang@intel.com> [1] https://lkml.kernel.org/r/CAP045AoMY4xf8aC_4QU_-j7obuEPYgTcnQQP3Yxk=2X90jtpjw@mail.gmail.com [2] https://lkml.kernel.org/r/20211117150258.GB5403@xsang-OptiPlex-9020 Fixes: 00b06da29cf9 ("signal: Add SA_IMMUTABLE to ensure forced siganls do not get changed") Fixes: a3616a3c0272 ("signal/m68k: Use force_sigsegv(SIGSEGV) in fpsp040_die") Fixes: 83a1f27ad773 ("signal/powerpc: On swapcontext failure force SIGSEGV") Fixes: 9bc508cf0791 ("signal/s390: Use force_sigsegv in default_trap_handler") Fixes: 086ec444f866 ("signal/sparc32: In setup_rt_frame and setup_fram use force_fatal_sig") Fixes: c317d306d550 ("signal/sparc32: Exit with a fatal signal when try_to_clear_window_buffer fails") Fixes: 695dd0d634df ("signal/x86: In emulate_vsyscall force a signal instead of calling do_exit") Fixes: 1fbd60df8a85 ("signal/vm86_32: Properly send SIGSEGV when the vm86 state cannot be saved.") Fixes: 941edc5bf174 ("exit/syscall_user_dispatch: Send ordinary signals on failure") Link: https://lkml.kernel.org/r/871r3dqfv8.fsf_-_@email.froward.int.ebiederm.org Reviewed-by: Kees Cook <keescook@chromium.org> Tested-by: Kees Cook <keescook@chromium.org> Tested-by: Kyle Huey <khuey@kylehuey.com> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
* Merge branch 'exit-cleanups-for-v5.16' of ↵Linus Torvalds2021-11-101-4/+8
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace Pull exit cleanups from Eric Biederman: "While looking at some issues related to the exit path in the kernel I found several instances where the code is not using the existing abstractions properly. This set of changes introduces force_fatal_sig a way of sending a signal and not allowing it to be caught, and corrects the misuse of the existing abstractions that I found. A lot of the misuse of the existing abstractions are silly things such as doing something after calling a no return function, rolling BUG by hand, doing more work than necessary to terminate a kernel thread, or calling do_exit(SIGKILL) instead of calling force_sig(SIGKILL). In the review a deficiency in force_fatal_sig and force_sig_seccomp where ptrace or sigaction could prevent the delivery of the signal was found. I have added a change that adds SA_IMMUTABLE to change that makes it impossible to interrupt the delivery of those signals, and allows backporting to fix force_sig_seccomp And Arnd found an issue where a function passed to kthread_run had the wrong prototype, and after my cleanup was failing to build." * 'exit-cleanups-for-v5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (23 commits) soc: ti: fix wkup_m3_rproc_boot_thread return type signal: Add SA_IMMUTABLE to ensure forced siganls do not get changed signal: Replace force_sigsegv(SIGSEGV) with force_fatal_sig(SIGSEGV) exit/r8188eu: Replace the macro thread_exit with a simple return 0 exit/rtl8712: Replace the macro thread_exit with a simple return 0 exit/rtl8723bs: Replace the macro thread_exit with a simple return 0 signal/x86: In emulate_vsyscall force a signal instead of calling do_exit signal/sparc32: In setup_rt_frame and setup_fram use force_fatal_sig signal/sparc32: Exit with a fatal signal when try_to_clear_window_buffer fails exit/syscall_user_dispatch: Send ordinary signals on failure signal: Implement force_fatal_sig exit/kthread: Have kernel threads return instead of calling do_exit signal/s390: Use force_sigsegv in default_trap_handler signal/vm86_32: Properly send SIGSEGV when the vm86 state cannot be saved. signal/vm86_32: Replace open coded BUG_ON with an actual BUG_ON signal/sparc: In setup_tsb_params convert open coded BUG into BUG signal/powerpc: On swapcontext failure force SIGSEGV signal/sh: Use force_sig(SIGKILL) instead of do_group_exit(SIGKILL) signal/mips: Update (_save|_restore)_fp_context to fail with -EFAULT signal/sparc32: Remove unreachable do_exit in do_sparc_fault ...
| * exit/syscall_user_dispatch: Send ordinary signals on failureEric W. Biederman2021-10-291-4/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Use force_fatal_sig instead of calling do_exit directly. This ensures the ordinary signal handling path gets invoked, core dumps as appropriate get created, and for multi-threaded processes all of the threads are terminated not just a single thread. When asked Gabriel Krisman Bertazi <krisman@collabora.com> said [1]: > ebiederm@xmission.com (Eric W. Biederman) asked: > > > Why does do_syscal_user_dispatch call do_exit(SIGSEGV) and > > do_exit(SIGSYS) instead of force_sig(SIGSEGV) and force_sig(SIGSYS)? > > > > Looking at the code these cases are not expected to happen, so I would > > be surprised if userspace depends on any particular behaviour on the > > failure path so I think we can change this. > > Hi Eric, > > There is not really a good reason, and the use case that originated the > feature doesn't rely on it. > > Unless I'm missing yet another problem and others correct me, I think > it makes sense to change it as you described. > > > Is using do_exit in this way something you copied from seccomp? > > I'm not sure, its been a while, but I think it might be just that. The > first prototype of SUD was implemented as a seccomp mode. If at some point it becomes interesting we could relax "force_fatal_sig(SIGSEGV)" to instead say "force_sig_fault(SIGSEGV, SEGV_MAPERR, sd->selector)". I avoid doing that in this patch to avoid making it possible to catch currently uncatchable signals. Cc: Gabriel Krisman Bertazi <krisman@collabora.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Andy Lutomirski <luto@kernel.org> [1] https://lkml.kernel.org/r/87mtr6gdvi.fsf@collabora.com Link: https://lkml.kernel.org/r/20211020174406.17889-14-ebiederm@xmission.com Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
* | entry: rseq: Call rseq_handle_notify_resume() in tracehook_notify_resume()Sean Christopherson2021-09-222-6/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Invoke rseq_handle_notify_resume() from tracehook_notify_resume() now that the two function are always called back-to-back by architectures that have rseq. The rseq helper is stubbed out for architectures that don't support rseq, i.e. this is a nop across the board. Note, tracehook_notify_resume() is horribly named and arguably does not belong in tracehook.h as literally every line of code in it has nothing to do with tracing. But, that's been true since commit a42c6ded827d ("move key_repace_session_keyring() into tracehook_notify_resume()") first usurped tracehook_notify_resume() back in 2012. Punt cleaning that mess up to future patches. No functional change intended. Acked-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20210901203030.1292304-3-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
* | KVM: rseq: Update rseq when processing NOTIFY_RESUME on xfer to KVM guestSean Christopherson2021-09-221-1/+3
|/ | | | | | | | | | | | | | | | | | | | | | | | | Invoke rseq's NOTIFY_RESUME handler when processing the flag prior to transferring to a KVM guest, which is roughly equivalent to an exit to userspace and processes many of the same pending actions. While the task cannot be in an rseq critical section as the KVM path is reachable only by via ioctl(KVM_RUN), the side effects that apply to rseq outside of a critical section still apply, e.g. the current CPU needs to be updated if the task is migrated. Clearing TIF_NOTIFY_RESUME without informing rseq can lead to segfaults and other badness in userspace VMMs that use rseq in combination with KVM, e.g. due to the CPU ID being stale after task migration. Fixes: 72c3c0fe54a3 ("x86/kvm: Use generic xfer to guest work function") Reported-by: Peter Foley <pefoley@google.com> Bisected-by: Doug Evans <dje@google.com> Acked-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: stable@vger.kernel.org Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20210901203030.1292304-2-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
* tick/nohz: Only check for RCU deferred wakeup on user/guest entry when neededFrederic Weisbecker2021-05-311-2/+3
| | | | | | | | | | | | | | | | | | | Checking for and processing RCU-nocb deferred wakeup upon user/guest entry is only relevant when nohz_full runs on the local CPU, otherwise the periodic tick should take care of it. Make sure we don't needlessly pollute these fast-paths as a -3% performance regression on a will-it-scale.per_process_ops has been reported so far. Fixes: 47b8ff194c1f (entry: Explicitly flush pending rcuog wakeup before last rescheduling point) Fixes: 4ae7dc97f726 (entry/kvm: Explicitly flush pending rcuog wakeup before last rescheduling point) Reported-by: kernel test robot <oliver.sang@intel.com> Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Paul E. McKenney <paulmck@kernel.org> Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/20210527113441.465489-1-frederic@kernel.org
* Merge tag 'core-entry-2021-04-26' of ↵Linus Torvalds2021-04-261-1/+1
|\ | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull core entry updates from Thomas Gleixner: "A trivial cleanup of typo fixes" * tag 'core-entry-2021-04-26' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: entry: Fix typos in comments
| * entry: Fix typos in commentsIngo Molnar2021-03-221-1/+1
| | | | | | | | | | | | | | | | | | | | | | Fix 3 single-word typos in the generic syscall entry code. Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
* | preempt/dynamic: Fix typo in macro conditional statementZhouyi Zhou2021-04-191-1/+1
|/ | | | | | | | | | | Commit 40607ee97e4e ("preempt/dynamic: Provide irqentry_exit_cond_resched() static call") tried to provide irqentry_exit_cond_resched() static call in irqentry_exit, but has a typo in macro conditional statement. Fixes: 40607ee97e4e ("preempt/dynamic: Provide irqentry_exit_cond_resched() static call") Signed-off-by: Zhouyi Zhou <zhouzhouyi@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20210410073523.5493-1-zhouzhouyi@gmail.com
* entry: Explicitly flush pending rcuog wakeup before last rescheduling pointFrederic Weisbecker2021-02-171-0/+7
| | | | | | | | | | | | | Following the idle loop model, cleanly check for pending rcuog wakeup before the last rescheduling point on resuming to user mode. This way we can avoid to do it from rcu_user_enter() with the last resort self-IPI hack that enforces rescheduling. Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/20210131230548.32970-5-frederic@kernel.org
* preempt/dynamic: Provide irqentry_exit_cond_resched() static callPeter Zijlstra (Intel)2021-02-171-1/+9
| | | | | | | | | | | | | | Provide static call to control IRQ preemption (called in CONFIG_PREEMPT) so that we can override its behaviour when preempt= is overriden. Since the default behaviour is full preemption, its call is initialized to provide IRQ preemption when preempt= isn't passed. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lkml.kernel.org/r/20210118141223.123667-8-frederic@kernel.org
* entry: Use different define for selector variable in SUDGabriel Krisman Bertazi2021-02-061-2/+2
| | | | | | | | | | | | | | | | | | | Michael Kerrisk suggested that, from an API perspective, it is a bad idea to share the PR_SYS_DISPATCH_ defines between the prctl operation and the selector variable. Therefore, define two new constants to be used by SUD's selector variable and update the corresponding documentation and test cases. While this changes the API syscall user dispatch has never been part of a Linux release, it will show up for the first time in 5.11. Suggested-by: Michael Kerrisk (man-pages) <mtk.manpages@gmail.com> Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/r/20210205184321.2062251-1-krisman@collabora.com
* entry: Ensure trap after single-step on system call returnGabriel Krisman Bertazi2021-02-061-10/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | Commit 299155244770 ("entry: Drop usage of TIF flags in the generic syscall code") introduced a bug on architectures using the generic syscall entry code, in which processes stopped by PTRACE_SYSCALL do not trap on syscall return after receiving a TIF_SINGLESTEP. The reason is that the meaning of TIF_SINGLESTEP flag is overloaded to cause the trap after a system call is executed, but since the above commit, the syscall call handler only checks for the SYSCALL_WORK flags on the exit work. Split the meaning of TIF_SINGLESTEP such that it only means single-step mode, and create a new type of SYSCALL_WORK to request a trap immediately after a syscall in single-step mode. In the current implementation, the SYSCALL_WORK flag shadows the TIF_SINGLESTEP flag for simplicity. Update x86 to flip this bit when a tracer enables single stepping. Fixes: 299155244770 ("entry: Drop usage of TIF flags in the generic syscall code") Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Kyle Huey <me@kylehuey.com> Link: https://lore.kernel.org/r/87h7mtc9pr.fsf_-_@collabora.com
* entry: Unbreak single step reporting behaviourYuxuan Shui2021-01-281-1/+1
| | | | | | | | | | | | | | | | | The move of TIF_SYSCALL_EMU to SYSCALL_WORK_SYSCALL_EMU broke single step reporting. The original code reported the single step when TIF_SINGLESTEP was set and TIF_SYSCALL_EMU was not set. The SYSCALL_WORK conversion got the logic wrong and now the reporting only happens when both bits are set. Restore the original behaviour. [ tglx: Massaged changelog and dropped the pointless double negation ] Fixes: 64eb35f701f0 ("ptrace: Migrate TIF_SYSCALL_EMU to use SYSCALL_WORK flag") Signed-off-by: Yuxuan Shui <yshuiv7@gmail.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Gabriel Krisman Bertazi <krisman@collabora.com> Link: https://lore.kernel.org/r/877do3gaq9.fsf@m5Zedd9JOGzJrf0
* Merge tag 'core-mm-2020-12-14' of ↵Linus Torvalds2020-12-141-0/+2
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull kmap updates from Thomas Gleixner: "The new preemtible kmap_local() implementation: - Consolidate all kmap_atomic() internals into a generic implementation which builds the base for the kmap_local() API and make the kmap_atomic() interface wrappers which handle the disabling/enabling of preemption and pagefaults. - Switch the storage from per-CPU to per task and provide scheduler support for clearing mapping when scheduling out and restoring them when scheduling back in. - Merge the migrate_disable/enable() code, which is also part of the scheduler pull request. This was required to make the kmap_local() interface available which does not disable preemption when a mapping is established. It has to disable migration instead to guarantee that the virtual address of the mapped slot is the same across preemption. - Provide better debug facilities: guard pages and enforced utilization of the mapping mechanics on 64bit systems when the architecture allows it. - Provide the new kmap_local() API which can now be used to cleanup the kmap_atomic() usage sites all over the place. Most of the usage sites do not require the implicit disabling of preemption and pagefaults so the penalty on 64bit and 32bit non-highmem systems is removed and quite some of the code can be simplified. A wholesale conversion is not possible because some usage depends on the implicit side effects and some need to be cleaned up because they work around these side effects. The migrate disable side effect is only effective on highmem systems and when enforced debugging is enabled. On 64bit and 32bit non-highmem systems the overhead is completely avoided" * tag 'core-mm-2020-12-14' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (33 commits) ARM: highmem: Fix cache_is_vivt() reference x86/crashdump/32: Simplify copy_oldmem_page() io-mapping: Provide iomap_local variant mm/highmem: Provide kmap_local* sched: highmem: Store local kmaps in task struct x86: Support kmap_local() forced debugging mm/highmem: Provide CONFIG_DEBUG_KMAP_LOCAL_FORCE_MAP mm/highmem: Provide and use CONFIG_DEBUG_KMAP_LOCAL microblaze/mm/highmem: Add dropped #ifdef back xtensa/mm/highmem: Make generic kmap_atomic() work correctly mm/highmem: Take kmap_high_get() properly into account highmem: High implementation details and document API Documentation/io-mapping: Remove outdated blurb io-mapping: Cleanup atomic iomap mm/highmem: Remove the old kmap_atomic cruft highmem: Get rid of kmap_types.h xtensa/mm/highmem: Switch to generic kmap atomic sparc/mm/highmem: Switch to generic kmap atomic powerpc/mm/highmem: Switch to generic kmap atomic nds32/mm/highmem: Switch to generic kmap atomic ...
| * sched: highmem: Store local kmaps in task structThomas Gleixner2020-11-241-0/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Instead of storing the map per CPU provide and use per task storage. That prepares for local kmaps which are preemptible. The context switch code is preparatory and not yet in use because kmap_atomic() runs with preemption disabled. Will be made usable in the next step. The context switch logic is safe even when an interrupt happens after clearing or before restoring the kmaps. The kmap index in task struct is not modified so any nesting kmap in an interrupt will use unused indices and on return the counter is the same as before. Also add an assert into the return to user space code. Going back to user space with an active kmap local is a nono. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20201118204007.372935758@linutronix.de
* | entry: Add syscall_exit_to_user_mode_work()Sven Schnelle2020-12-021-2/+12
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This is the same as syscall_exit_to_user_mode() but without calling exit_to_user_mode(). This can be used if there is an architectural reason to avoid the combo function, e.g. restarting a syscall without returning to userspace. Before returning to user space the caller has to invoke exit_to_user_mode(). [ tglx: Amended comments ] Signed-off-by: Sven Schnelle <svens@linux.ibm.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/r/20201201142755.31931-6-svens@linux.ibm.com
* | entry: Add exit_to_user_mode() wrapperSven Schnelle2020-12-021-12/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Called from architecture specific code when syscall_exit_to_user_mode() is not suitable. It simply calls __exit_to_user_mode(). This way __exit_to_user_mode() can still be inlined because it is declared static __always_inline. [ tglx: Amended comments and moved it to a different place in the header ] Signed-off-by: Sven Schnelle <svens@linux.ibm.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/r/20201201142755.31931-5-svens@linux.ibm.com
* | entry_Add_enter_from_user_mode_wrapperSven Schnelle2020-12-021-10/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | To be called from architecture specific code if the combo interfaces are not suitable. It simply calls __enter_from_user_mode(). This way __enter_from_user_mode will still be inlined because it is declared static __always_inline. [ tglx: Amend comments and move it to a different location in the header ] Signed-off-by: Sven Schnelle <svens@linux.ibm.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/r/20201201142755.31931-4-svens@linux.ibm.com
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