diff options
| -rw-r--r-- | arch/x86/include/asm/atomic.h | 4 | ||||
| -rw-r--r-- | include/asm-generic/atomic-instrumented.h | 21 |
2 files changed, 25 insertions, 0 deletions
diff --git a/arch/x86/include/asm/atomic.h b/arch/x86/include/asm/atomic.h index 33afc966d6a9..0db6bec95489 100644 --- a/arch/x86/include/asm/atomic.h +++ b/arch/x86/include/asm/atomic.h @@ -24,6 +24,10 @@ */ static __always_inline int arch_atomic_read(const atomic_t *v) { + /* + * Note for KASAN: we deliberately don't use READ_ONCE_NOCHECK() here, + * it's non-inlined function that increases binary size and stack usage. + */ return READ_ONCE((v)->counter); } diff --git a/include/asm-generic/atomic-instrumented.h b/include/asm-generic/atomic-instrumented.h index 82e080505982..ec07f23678ea 100644 --- a/include/asm-generic/atomic-instrumented.h +++ b/include/asm-generic/atomic-instrumented.h @@ -1,3 +1,15 @@ +/* + * This file provides wrappers with KASAN instrumentation for atomic operations. + * To use this functionality an arch's atomic.h file needs to define all + * atomic operations with arch_ prefix (e.g. arch_atomic_read()) and include + * this file at the end. This file provides atomic_read() that forwards to + * arch_atomic_read() for actual atomic operation. + * Note: if an arch atomic operation is implemented by means of other atomic + * operations (e.g. atomic_read()/atomic_cmpxchg() loop), then it needs to use + * arch_ variants (i.e. arch_atomic_read()/arch_atomic_cmpxchg()) to avoid + * double instrumentation. + */ + #ifndef _LINUX_ATOMIC_INSTRUMENTED_H #define _LINUX_ATOMIC_INSTRUMENTED_H @@ -442,6 +454,15 @@ cmpxchg64_local_size(volatile u64 *ptr, u64 old, u64 new) (u64)(new))); \ }) +/* + * Originally we had the following code here: + * __typeof__(p1) ____p1 = (p1); + * kasan_check_write(____p1, 2 * sizeof(*____p1)); + * arch_cmpxchg_double(____p1, (p2), (o1), (o2), (n1), (n2)); + * But it leads to compilation failures (see gcc issue 72873). + * So for now it's left non-instrumented. + * There are few callers of cmpxchg_double(), so it's not critical. + */ #define cmpxchg_double(p1, p2, o1, o2, n1, n2) \ ({ \ arch_cmpxchg_double((p1), (p2), (o1), (o2), (n1), (n2)); \ |