0,0 → 1,114 |
#ifndef _ASM_X86_CMPXCHG_32_H |
#define _ASM_X86_CMPXCHG_32_H |
|
/* |
* Note: if you use set64_bit(), __cmpxchg64(), or their variants, you |
* you need to test for the feature in boot_cpu_data. |
*/ |
|
/* |
* CMPXCHG8B only writes to the target if we had the previous |
* value in registers, otherwise it acts as a read and gives us the |
* "new previous" value. That is why there is a loop. Preloading |
* EDX:EAX is a performance optimization: in the common case it means |
* we need only one locked operation. |
* |
* A SIMD/3DNOW!/MMX/FPU 64-bit store here would require at the very |
* least an FPU save and/or %cr0.ts manipulation. |
* |
* cmpxchg8b must be used with the lock prefix here to allow the |
* instruction to be executed atomically. We need to have the reader |
* side to see the coherent 64bit value. |
*/ |
static inline void set_64bit(volatile u64 *ptr, u64 value) |
{ |
u32 low = value; |
u32 high = value >> 32; |
u64 prev = *ptr; |
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asm volatile("\n1:\t" |
LOCK_PREFIX "cmpxchg8b %0\n\t" |
"jnz 1b" |
: "=m" (*ptr), "+A" (prev) |
: "b" (low), "c" (high) |
: "memory"); |
} |
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#ifdef CONFIG_X86_CMPXCHG64 |
#define cmpxchg64(ptr, o, n) \ |
((__typeof__(*(ptr)))__cmpxchg64((ptr), (unsigned long long)(o), \ |
(unsigned long long)(n))) |
#define cmpxchg64_local(ptr, o, n) \ |
((__typeof__(*(ptr)))__cmpxchg64_local((ptr), (unsigned long long)(o), \ |
(unsigned long long)(n))) |
#endif |
|
static inline u64 __cmpxchg64(volatile u64 *ptr, u64 old, u64 new) |
{ |
u64 prev; |
asm volatile(LOCK_PREFIX "cmpxchg8b %1" |
: "=A" (prev), |
"+m" (*ptr) |
: "b" ((u32)new), |
"c" ((u32)(new >> 32)), |
"0" (old) |
: "memory"); |
return prev; |
} |
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static inline u64 __cmpxchg64_local(volatile u64 *ptr, u64 old, u64 new) |
{ |
u64 prev; |
asm volatile("cmpxchg8b %1" |
: "=A" (prev), |
"+m" (*ptr) |
: "b" ((u32)new), |
"c" ((u32)(new >> 32)), |
"0" (old) |
: "memory"); |
return prev; |
} |
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#ifndef CONFIG_X86_CMPXCHG64 |
/* |
* Building a kernel capable running on 80386 and 80486. It may be necessary |
* to simulate the cmpxchg8b on the 80386 and 80486 CPU. |
*/ |
|
#define cmpxchg64(ptr, o, n) \ |
({ \ |
__typeof__(*(ptr)) __ret; \ |
__typeof__(*(ptr)) __old = (o); \ |
__typeof__(*(ptr)) __new = (n); \ |
alternative_io(LOCK_PREFIX_HERE \ |
"call cmpxchg8b_emu", \ |
"lock; cmpxchg8b (%%esi)" , \ |
X86_FEATURE_CX8, \ |
"=A" (__ret), \ |
"S" ((ptr)), "0" (__old), \ |
"b" ((unsigned int)__new), \ |
"c" ((unsigned int)(__new>>32)) \ |
: "memory"); \ |
__ret; }) |
|
|
#define cmpxchg64_local(ptr, o, n) \ |
({ \ |
__typeof__(*(ptr)) __ret; \ |
__typeof__(*(ptr)) __old = (o); \ |
__typeof__(*(ptr)) __new = (n); \ |
alternative_io("call cmpxchg8b_emu", \ |
"cmpxchg8b (%%esi)" , \ |
X86_FEATURE_CX8, \ |
"=A" (__ret), \ |
"S" ((ptr)), "0" (__old), \ |
"b" ((unsigned int)__new), \ |
"c" ((unsigned int)(__new>>32)) \ |
: "memory"); \ |
__ret; }) |
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#endif |
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#define system_has_cmpxchg_double() cpu_has_cx8 |
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#endif /* _ASM_X86_CMPXCHG_32_H */ |