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| author | Will Deacon <will.deacon@arm.com> | 2013-10-09 20:01:21 +0400 |
|---|---|---|
| committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2013-10-29 15:06:06 +0400 |
| commit | 2523c67bb6962f98193dce1c73b6efb65a6ea92c (patch) | |
| tree | 0c23d146be95ffcb82405c6b6770ae52421ba19e /arch/arm/include/asm/cmpxchg.h | |
| parent | 494e492dd88d36cd201eae99873492450d1e9b4f (diff) | |
| download | linux-2523c67bb6962f98193dce1c73b6efb65a6ea92c.tar.xz | |
ARM: 7852/1: cmpxchg: implement barrier-less cmpxchg64_local
Our cmpxchg64 macros are wrappers around atomic64_cmpxchg. Whilst this is
great for code re-use, there is a case for barrier-less cmpxchg where it
is known to be safe (for example cmpxchg64_local and cmpxchg-based
lockrefs).
This patch introduces a 64-bit cmpxchg implementation specifically
for the cmpxchg64_* macros, so that it can be later used by the lockref
code.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm/include/asm/cmpxchg.h')
| -rw-r--r-- | arch/arm/include/asm/cmpxchg.h | 52 |
1 files changed, 42 insertions, 10 deletions
diff --git a/arch/arm/include/asm/cmpxchg.h b/arch/arm/include/asm/cmpxchg.h index 4f009c10540d..fbd978fc248f 100644 --- a/arch/arm/include/asm/cmpxchg.h +++ b/arch/arm/include/asm/cmpxchg.h @@ -223,6 +223,42 @@ static inline unsigned long __cmpxchg_local(volatile void *ptr, return ret; } +static inline unsigned long long __cmpxchg64(unsigned long long *ptr, + unsigned long long old, + unsigned long long new) +{ + unsigned long long oldval; + unsigned long res; + + __asm__ __volatile__( +"1: ldrexd %1, %H1, [%3]\n" +" teq %1, %4\n" +" teqeq %H1, %H4\n" +" bne 2f\n" +" strexd %0, %5, %H5, [%3]\n" +" teq %0, #0\n" +" bne 1b\n" +"2:" + : "=&r" (res), "=&r" (oldval), "+Qo" (*ptr) + : "r" (ptr), "r" (old), "r" (new) + : "cc"); + + return oldval; +} + +static inline unsigned long long __cmpxchg64_mb(unsigned long long *ptr, + unsigned long long old, + unsigned long long new) +{ + unsigned long long ret; + + smp_mb(); + ret = __cmpxchg64(ptr, old, new); + smp_mb(); + + return ret; +} + #define cmpxchg_local(ptr,o,n) \ ((__typeof__(*(ptr)))__cmpxchg_local((ptr), \ (unsigned long)(o), \ @@ -230,18 +266,14 @@ static inline unsigned long __cmpxchg_local(volatile void *ptr, sizeof(*(ptr)))) #define cmpxchg64(ptr, o, n) \ - ((__typeof__(*(ptr)))atomic64_cmpxchg(container_of((ptr), \ - atomic64_t, \ - counter), \ - (unsigned long long)(o), \ - (unsigned long long)(n))) + ((__typeof__(*(ptr)))__cmpxchg64_mb((ptr), \ + (unsigned long long)(o), \ + (unsigned long long)(n))) #define cmpxchg64_local(ptr, o, n) \ - ((__typeof__(*(ptr)))local64_cmpxchg(container_of((ptr), \ - local64_t, \ - a), \ - (unsigned long long)(o), \ - (unsigned long long)(n))) + ((__typeof__(*(ptr)))__cmpxchg64((ptr), \ + (unsigned long long)(o), \ + (unsigned long long)(n))) #endif /* __LINUX_ARM_ARCH__ >= 6 */ |