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author | Linus Torvalds <torvalds@linux-foundation.org> | 2017-12-23 11:53:04 -0800 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2017-12-23 11:53:04 -0800 |
commit | caf9a82657b313106aae8f4a35936c116a152299 (patch) | |
tree | 525b164e34122b052ad06f56e6f88ed846471a58 /arch/x86/include/asm/tlbflush.h | |
parent | 9c294ec08408ed90c0f2d994a7979366675e3734 (diff) | |
parent | f6c4fd506cb626e4346aa81688f255e593a7c5a0 (diff) | |
download | linux-stable-caf9a82657b313106aae8f4a35936c116a152299.tar.gz linux-stable-caf9a82657b313106aae8f4a35936c116a152299.tar.bz2 linux-stable-caf9a82657b313106aae8f4a35936c116a152299.zip |
Merge branch 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 PTI preparatory patches from Thomas Gleixner:
"Todays Advent calendar window contains twentyfour easy to digest
patches. The original plan was to have twenty three matching the date,
but a late fixup made that moot.
- Move the cpu_entry_area mapping out of the fixmap into a separate
address space. That's necessary because the fixmap becomes too big
with NRCPUS=8192 and this caused already subtle and hard to
diagnose failures.
The top most patch is fresh from today and cures a brain slip of
that tall grumpy german greybeard, who ignored the intricacies of
32bit wraparounds.
- Limit the number of CPUs on 32bit to 64. That's insane big already,
but at least it's small enough to prevent address space issues with
the cpu_entry_area map, which have been observed and debugged with
the fixmap code
- A few TLB flush fixes in various places plus documentation which of
the TLB functions should be used for what.
- Rename the SYSENTER stack to CPU_ENTRY_AREA stack as it is used for
more than sysenter now and keeping the name makes backtraces
confusing.
- Prevent LDT inheritance on exec() by moving it to arch_dup_mmap(),
which is only invoked on fork().
- Make vysycall more robust.
- A few fixes and cleanups of the debug_pagetables code. Check
PAGE_PRESENT instead of checking the PTE for 0 and a cleanup of the
C89 initialization of the address hint array which already was out
of sync with the index enums.
- Move the ESPFIX init to a different place to prepare for PTI.
- Several code moves with no functional change to make PTI
integration simpler and header files less convoluted.
- Documentation fixes and clarifications"
* 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (24 commits)
x86/cpu_entry_area: Prevent wraparound in setup_cpu_entry_area_ptes() on 32bit
init: Invoke init_espfix_bsp() from mm_init()
x86/cpu_entry_area: Move it out of the fixmap
x86/cpu_entry_area: Move it to a separate unit
x86/mm: Create asm/invpcid.h
x86/mm: Put MMU to hardware ASID translation in one place
x86/mm: Remove hard-coded ASID limit checks
x86/mm: Move the CR3 construction functions to tlbflush.h
x86/mm: Add comments to clarify which TLB-flush functions are supposed to flush what
x86/mm: Remove superfluous barriers
x86/mm: Use __flush_tlb_one() for kernel memory
x86/microcode: Dont abuse the TLB-flush interface
x86/uv: Use the right TLB-flush API
x86/entry: Rename SYSENTER_stack to CPU_ENTRY_AREA_entry_stack
x86/doc: Remove obvious weirdnesses from the x86 MM layout documentation
x86/mm/64: Improve the memory map documentation
x86/ldt: Prevent LDT inheritance on exec
x86/ldt: Rework locking
arch, mm: Allow arch_dup_mmap() to fail
x86/vsyscall/64: Warn and fail vsyscall emulation in NATIVE mode
...
Diffstat (limited to 'arch/x86/include/asm/tlbflush.h')
-rw-r--r-- | arch/x86/include/asm/tlbflush.h | 136 |
1 files changed, 72 insertions, 64 deletions
diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflush.h index 877b5c1a1b12..e1884cf35257 100644 --- a/arch/x86/include/asm/tlbflush.h +++ b/arch/x86/include/asm/tlbflush.h @@ -9,70 +9,66 @@ #include <asm/cpufeature.h> #include <asm/special_insns.h> #include <asm/smp.h> +#include <asm/invpcid.h> -static inline void __invpcid(unsigned long pcid, unsigned long addr, - unsigned long type) +static inline u64 inc_mm_tlb_gen(struct mm_struct *mm) { - struct { u64 d[2]; } desc = { { pcid, addr } }; - /* - * The memory clobber is because the whole point is to invalidate - * stale TLB entries and, especially if we're flushing global - * mappings, we don't want the compiler to reorder any subsequent - * memory accesses before the TLB flush. - * - * The hex opcode is invpcid (%ecx), %eax in 32-bit mode and - * invpcid (%rcx), %rax in long mode. + * Bump the generation count. This also serves as a full barrier + * that synchronizes with switch_mm(): callers are required to order + * their read of mm_cpumask after their writes to the paging + * structures. */ - asm volatile (".byte 0x66, 0x0f, 0x38, 0x82, 0x01" - : : "m" (desc), "a" (type), "c" (&desc) : "memory"); + return atomic64_inc_return(&mm->context.tlb_gen); } -#define INVPCID_TYPE_INDIV_ADDR 0 -#define INVPCID_TYPE_SINGLE_CTXT 1 -#define INVPCID_TYPE_ALL_INCL_GLOBAL 2 -#define INVPCID_TYPE_ALL_NON_GLOBAL 3 +/* There are 12 bits of space for ASIDS in CR3 */ +#define CR3_HW_ASID_BITS 12 +/* + * When enabled, PAGE_TABLE_ISOLATION consumes a single bit for + * user/kernel switches + */ +#define PTI_CONSUMED_ASID_BITS 0 -/* Flush all mappings for a given pcid and addr, not including globals. */ -static inline void invpcid_flush_one(unsigned long pcid, - unsigned long addr) -{ - __invpcid(pcid, addr, INVPCID_TYPE_INDIV_ADDR); -} +#define CR3_AVAIL_ASID_BITS (CR3_HW_ASID_BITS - PTI_CONSUMED_ASID_BITS) +/* + * ASIDs are zero-based: 0->MAX_AVAIL_ASID are valid. -1 below to account + * for them being zero-based. Another -1 is because ASID 0 is reserved for + * use by non-PCID-aware users. + */ +#define MAX_ASID_AVAILABLE ((1 << CR3_AVAIL_ASID_BITS) - 2) -/* Flush all mappings for a given PCID, not including globals. */ -static inline void invpcid_flush_single_context(unsigned long pcid) +static inline u16 kern_pcid(u16 asid) { - __invpcid(pcid, 0, INVPCID_TYPE_SINGLE_CTXT); + VM_WARN_ON_ONCE(asid > MAX_ASID_AVAILABLE); + /* + * If PCID is on, ASID-aware code paths put the ASID+1 into the + * PCID bits. This serves two purposes. It prevents a nasty + * situation in which PCID-unaware code saves CR3, loads some other + * value (with PCID == 0), and then restores CR3, thus corrupting + * the TLB for ASID 0 if the saved ASID was nonzero. It also means + * that any bugs involving loading a PCID-enabled CR3 with + * CR4.PCIDE off will trigger deterministically. + */ + return asid + 1; } -/* Flush all mappings, including globals, for all PCIDs. */ -static inline void invpcid_flush_all(void) +struct pgd_t; +static inline unsigned long build_cr3(pgd_t *pgd, u16 asid) { - __invpcid(0, 0, INVPCID_TYPE_ALL_INCL_GLOBAL); + if (static_cpu_has(X86_FEATURE_PCID)) { + return __sme_pa(pgd) | kern_pcid(asid); + } else { + VM_WARN_ON_ONCE(asid != 0); + return __sme_pa(pgd); + } } -/* Flush all mappings for all PCIDs except globals. */ -static inline void invpcid_flush_all_nonglobals(void) +static inline unsigned long build_cr3_noflush(pgd_t *pgd, u16 asid) { - __invpcid(0, 0, INVPCID_TYPE_ALL_NON_GLOBAL); -} - -static inline u64 inc_mm_tlb_gen(struct mm_struct *mm) -{ - u64 new_tlb_gen; - - /* - * Bump the generation count. This also serves as a full barrier - * that synchronizes with switch_mm(): callers are required to order - * their read of mm_cpumask after their writes to the paging - * structures. - */ - smp_mb__before_atomic(); - new_tlb_gen = atomic64_inc_return(&mm->context.tlb_gen); - smp_mb__after_atomic(); - - return new_tlb_gen; + VM_WARN_ON_ONCE(asid > MAX_ASID_AVAILABLE); + VM_WARN_ON_ONCE(!this_cpu_has(X86_FEATURE_PCID)); + return __sme_pa(pgd) | kern_pcid(asid) | CR3_NOFLUSH; } #ifdef CONFIG_PARAVIRT @@ -237,6 +233,9 @@ static inline void cr4_set_bits_and_update_boot(unsigned long mask) extern void initialize_tlbstate_and_flush(void); +/* + * flush the entire current user mapping + */ static inline void __native_flush_tlb(void) { /* @@ -249,20 +248,12 @@ static inline void __native_flush_tlb(void) preempt_enable(); } -static inline void __native_flush_tlb_global_irq_disabled(void) -{ - unsigned long cr4; - - cr4 = this_cpu_read(cpu_tlbstate.cr4); - /* clear PGE */ - native_write_cr4(cr4 & ~X86_CR4_PGE); - /* write old PGE again and flush TLBs */ - native_write_cr4(cr4); -} - +/* + * flush everything + */ static inline void __native_flush_tlb_global(void) { - unsigned long flags; + unsigned long cr4, flags; if (static_cpu_has(X86_FEATURE_INVPCID)) { /* @@ -280,22 +271,36 @@ static inline void __native_flush_tlb_global(void) */ raw_local_irq_save(flags); - __native_flush_tlb_global_irq_disabled(); + cr4 = this_cpu_read(cpu_tlbstate.cr4); + /* toggle PGE */ + native_write_cr4(cr4 ^ X86_CR4_PGE); + /* write old PGE again and flush TLBs */ + native_write_cr4(cr4); raw_local_irq_restore(flags); } +/* + * flush one page in the user mapping + */ static inline void __native_flush_tlb_single(unsigned long addr) { asm volatile("invlpg (%0)" ::"r" (addr) : "memory"); } +/* + * flush everything + */ static inline void __flush_tlb_all(void) { - if (boot_cpu_has(X86_FEATURE_PGE)) + if (boot_cpu_has(X86_FEATURE_PGE)) { __flush_tlb_global(); - else + } else { + /* + * !PGE -> !PCID (setup_pcid()), thus every flush is total. + */ __flush_tlb(); + } /* * Note: if we somehow had PCID but not PGE, then this wouldn't work -- @@ -306,6 +311,9 @@ static inline void __flush_tlb_all(void) */ } +/* + * flush one page in the kernel mapping + */ static inline void __flush_tlb_one(unsigned long addr) { count_vm_tlb_event(NR_TLB_LOCAL_FLUSH_ONE); |