diff options
author | Linus Torvalds <torvalds@linux-foundation.org> | 2017-09-04 11:52:29 -0700 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2017-09-04 11:52:29 -0700 |
commit | 5f82e71a001d14824a7728ad9e49f6aea420f161 (patch) | |
tree | bf5dfa7cf0840ec834899ae925913973bd1e65d1 /arch/x86/include/asm/refcount.h | |
parent | 6c51e67b64d169419fb13318035bb442f9176612 (diff) | |
parent | edc2988c548db05e33b921fed15821010bc74895 (diff) |
Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull locking updates from Ingo Molnar:
- Add 'cross-release' support to lockdep, which allows APIs like
completions, where it's not the 'owner' who releases the lock, to be
tracked. It's all activated automatically under
CONFIG_PROVE_LOCKING=y.
- Clean up (restructure) the x86 atomics op implementation to be more
readable, in preparation of KASAN annotations. (Dmitry Vyukov)
- Fix static keys (Paolo Bonzini)
- Add killable versions of down_read() et al (Kirill Tkhai)
- Rework and fix jump_label locking (Marc Zyngier, Paolo Bonzini)
- Rework (and fix) tlb_flush_pending() barriers (Peter Zijlstra)
- Remove smp_mb__before_spinlock() and convert its usages, introduce
smp_mb__after_spinlock() (Peter Zijlstra)
* 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (56 commits)
locking/lockdep/selftests: Fix mixed read-write ABBA tests
sched/completion: Avoid unnecessary stack allocation for COMPLETION_INITIALIZER_ONSTACK()
acpi/nfit: Fix COMPLETION_INITIALIZER_ONSTACK() abuse
locking/pvqspinlock: Relax cmpxchg's to improve performance on some architectures
smp: Avoid using two cache lines for struct call_single_data
locking/lockdep: Untangle xhlock history save/restore from task independence
locking/refcounts, x86/asm: Disable CONFIG_ARCH_HAS_REFCOUNT for the time being
futex: Remove duplicated code and fix undefined behaviour
Documentation/locking/atomic: Finish the document...
locking/lockdep: Fix workqueue crossrelease annotation
workqueue/lockdep: 'Fix' flush_work() annotation
locking/lockdep/selftests: Add mixed read-write ABBA tests
mm, locking/barriers: Clarify tlb_flush_pending() barriers
locking/lockdep: Make CONFIG_LOCKDEP_CROSSRELEASE and CONFIG_LOCKDEP_COMPLETIONS truly non-interactive
locking/lockdep: Explicitly initialize wq_barrier::done::map
locking/lockdep: Rename CONFIG_LOCKDEP_COMPLETE to CONFIG_LOCKDEP_COMPLETIONS
locking/lockdep: Reword title of LOCKDEP_CROSSRELEASE config
locking/lockdep: Make CONFIG_LOCKDEP_CROSSRELEASE part of CONFIG_PROVE_LOCKING
locking/refcounts, x86/asm: Implement fast refcount overflow protection
locking/lockdep: Fix the rollback and overwrite detection logic in crossrelease
...
Diffstat (limited to 'arch/x86/include/asm/refcount.h')
-rw-r--r-- | arch/x86/include/asm/refcount.h | 109 |
1 files changed, 109 insertions, 0 deletions
diff --git a/arch/x86/include/asm/refcount.h b/arch/x86/include/asm/refcount.h new file mode 100644 index 000000000000..ff871210b9f2 --- /dev/null +++ b/arch/x86/include/asm/refcount.h @@ -0,0 +1,109 @@ +#ifndef __ASM_X86_REFCOUNT_H +#define __ASM_X86_REFCOUNT_H +/* + * x86-specific implementation of refcount_t. Based on PAX_REFCOUNT from + * PaX/grsecurity. + */ +#include <linux/refcount.h> + +/* + * This is the first portion of the refcount error handling, which lives in + * .text.unlikely, and is jumped to from the CPU flag check (in the + * following macros). This saves the refcount value location into CX for + * the exception handler to use (in mm/extable.c), and then triggers the + * central refcount exception. The fixup address for the exception points + * back to the regular execution flow in .text. + */ +#define _REFCOUNT_EXCEPTION \ + ".pushsection .text.unlikely\n" \ + "111:\tlea %[counter], %%" _ASM_CX "\n" \ + "112:\t" ASM_UD0 "\n" \ + ASM_UNREACHABLE \ + ".popsection\n" \ + "113:\n" \ + _ASM_EXTABLE_REFCOUNT(112b, 113b) + +/* Trigger refcount exception if refcount result is negative. */ +#define REFCOUNT_CHECK_LT_ZERO \ + "js 111f\n\t" \ + _REFCOUNT_EXCEPTION + +/* Trigger refcount exception if refcount result is zero or negative. */ +#define REFCOUNT_CHECK_LE_ZERO \ + "jz 111f\n\t" \ + REFCOUNT_CHECK_LT_ZERO + +/* Trigger refcount exception unconditionally. */ +#define REFCOUNT_ERROR \ + "jmp 111f\n\t" \ + _REFCOUNT_EXCEPTION + +static __always_inline void refcount_add(unsigned int i, refcount_t *r) +{ + asm volatile(LOCK_PREFIX "addl %1,%0\n\t" + REFCOUNT_CHECK_LT_ZERO + : [counter] "+m" (r->refs.counter) + : "ir" (i) + : "cc", "cx"); +} + +static __always_inline void refcount_inc(refcount_t *r) +{ + asm volatile(LOCK_PREFIX "incl %0\n\t" + REFCOUNT_CHECK_LT_ZERO + : [counter] "+m" (r->refs.counter) + : : "cc", "cx"); +} + +static __always_inline void refcount_dec(refcount_t *r) +{ + asm volatile(LOCK_PREFIX "decl %0\n\t" + REFCOUNT_CHECK_LE_ZERO + : [counter] "+m" (r->refs.counter) + : : "cc", "cx"); +} + +static __always_inline __must_check +bool refcount_sub_and_test(unsigned int i, refcount_t *r) +{ + GEN_BINARY_SUFFIXED_RMWcc(LOCK_PREFIX "subl", REFCOUNT_CHECK_LT_ZERO, + r->refs.counter, "er", i, "%0", e); +} + +static __always_inline __must_check bool refcount_dec_and_test(refcount_t *r) +{ + GEN_UNARY_SUFFIXED_RMWcc(LOCK_PREFIX "decl", REFCOUNT_CHECK_LT_ZERO, + r->refs.counter, "%0", e); +} + +static __always_inline __must_check +bool refcount_add_not_zero(unsigned int i, refcount_t *r) +{ + int c, result; + + c = atomic_read(&(r->refs)); + do { + if (unlikely(c == 0)) + return false; + + result = c + i; + + /* Did we try to increment from/to an undesirable state? */ + if (unlikely(c < 0 || c == INT_MAX || result < c)) { + asm volatile(REFCOUNT_ERROR + : : [counter] "m" (r->refs.counter) + : "cc", "cx"); + break; + } + + } while (!atomic_try_cmpxchg(&(r->refs), &c, result)); + + return c != 0; +} + +static __always_inline __must_check bool refcount_inc_not_zero(refcount_t *r) +{ + return refcount_add_not_zero(1, r); +} + +#endif |