diff options
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/include/asm/atomic_32.h | 22 | ||||
| -rw-r--r-- | arch/x86/lib/atomic64_32.c | 23 |
2 files changed, 23 insertions, 22 deletions
diff --git a/arch/x86/include/asm/atomic_32.h b/arch/x86/include/asm/atomic_32.h index d7c8849b8c6..dc5a667ff79 100644 --- a/arch/x86/include/asm/atomic_32.h +++ b/arch/x86/include/asm/atomic_32.h @@ -295,6 +295,28 @@ extern void atomic64_set(atomic64_t *ptr, u64 new_val); * * Atomically reads the value of @ptr and returns it. */ +static inline u64 atomic64_read(atomic64_t *ptr) +{ + u64 res; + + /* + * Note, we inline this atomic64_t primitive because + * it only clobbers EAX/EDX and leaves the others + * untouched. We also (somewhat subtly) rely on the + * fact that cmpxchg8b returns the current 64-bit value + * of the memory location we are touching: + */ + asm volatile( + "mov %%ebx, %%eax\n\t" + "mov %%ecx, %%edx\n\t" + LOCK_PREFIX "cmpxchg8b %1\n" + : "=&A" (res) + : "m" (*ptr) + ); + + return res; +} + extern u64 atomic64_read(atomic64_t *ptr); /** diff --git a/arch/x86/lib/atomic64_32.c b/arch/x86/lib/atomic64_32.c index 1d98c9eb6ea..824fa0be55a 100644 --- a/arch/x86/lib/atomic64_32.c +++ b/arch/x86/lib/atomic64_32.c @@ -66,31 +66,10 @@ void atomic64_set(atomic64_t *ptr, u64 new_val) { atomic64_xchg(ptr, new_val); } -EXPORT_SYMBOL(atomic64_read); +EXPORT_SYMBOL(atomic64_set); /** - * atomic64_read - read atomic64 variable - * @ptr: pointer to type atomic64_t - * - * Atomically reads the value of @ptr and returns it. - */ -u64 atomic64_read(atomic64_t *ptr) -{ - u64 res; - - asm volatile( - "mov %%ebx, %%eax\n\t" - "mov %%ecx, %%edx\n\t" - LOCK_PREFIX "cmpxchg8b %1\n" - : "+A" (res) - : "m" (*ptr) - ); - - return res; -} EXPORT_SYMBOL(atomic64_read); - -/** * atomic64_add_return - add and return * @delta: integer value to add * @ptr: pointer to type atomic64_t |