115 lines
3.1 KiB
C
115 lines
3.1 KiB
C
#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;
|
|
|
|
asm volatile("\n1:\t"
|
|
LOCK_PREFIX "cmpxchg8b %0\n\t"
|
|
"jnz 1b"
|
|
: "=m" (*ptr), "+A" (prev)
|
|
: "b" (low), "c" (high)
|
|
: "memory");
|
|
}
|
|
|
|
#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;
|
|
}
|
|
|
|
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;
|
|
}
|
|
|
|
#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; })
|
|
|
|
#endif
|
|
|
|
#define system_has_cmpxchg_double() cpu_has_cx8
|
|
|
|
#endif /* _ASM_X86_CMPXCHG_32_H */
|