diff options
Diffstat (limited to 'include/asm-x86/cmpxchg_64.h')
| -rw-r--r-- | include/asm-x86/cmpxchg_64.h | 37 |
1 files changed, 37 insertions, 0 deletions
diff --git a/include/asm-x86/cmpxchg_64.h b/include/asm-x86/cmpxchg_64.h index d9b26b9a28c..17463ccf816 100644 --- a/include/asm-x86/cmpxchg_64.h +++ b/include/asm-x86/cmpxchg_64.h @@ -93,6 +93,39 @@ static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old, return old; } +/* + * Always use locked operations when touching memory shared with a + * hypervisor, since the system may be SMP even if the guest kernel + * isn't. + */ +static inline unsigned long __sync_cmpxchg(volatile void *ptr, + unsigned long old, + unsigned long new, int size) +{ + unsigned long prev; + switch (size) { + case 1: + asm volatile("lock; cmpxchgb %b1,%2" + : "=a"(prev) + : "q"(new), "m"(*__xg(ptr)), "0"(old) + : "memory"); + return prev; + case 2: + asm volatile("lock; cmpxchgw %w1,%2" + : "=a"(prev) + : "r"(new), "m"(*__xg(ptr)), "0"(old) + : "memory"); + return prev; + case 4: + asm volatile("lock; cmpxchgl %1,%2" + : "=a"(prev) + : "r"(new), "m"(*__xg(ptr)), "0"(old) + : "memory"); + return prev; + } + return old; +} + static inline unsigned long __cmpxchg_local(volatile void *ptr, unsigned long old, unsigned long new, int size) @@ -139,6 +172,10 @@ static inline unsigned long __cmpxchg_local(volatile void *ptr, ((__typeof__(*(ptr)))__cmpxchg_local((ptr), (unsigned long)(o), \ (unsigned long)(n), \ sizeof(*(ptr)))) +#define sync_cmpxchg(ptr, o, n) \ + ((__typeof__(*(ptr)))__sync_cmpxchg((ptr), (unsigned long)(o), \ + (unsigned long)(n), \ + sizeof(*(ptr)))) #define cmpxchg64_local(ptr, o, n) \ ({ \ BUILD_BUG_ON(sizeof(*(ptr)) != 8); \ |