aboutsummaryrefslogtreecommitdiffstats
path: root/arch/x86/include/asm/cmpxchg_64.h
blob: 485ae415faecd5c70705e456e892c1cdf72f7b5f (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
#ifndef _ASM_X86_CMPXCHG_64_H
#define _ASM_X86_CMPXCHG_64_H

#include <asm/alternative.h> /* Provides LOCK_PREFIX */

#define __xg(x) ((volatile long *)(x))

static inline void set_64bit(volatile unsigned long *ptr, unsigned long val)
{
	*ptr = val;
}

#define _set_64bit set_64bit

extern void __xchg_wrong_size(void);
extern void __cmpxchg_wrong_size(void);

/*
 * Note: no "lock" prefix even on SMP: xchg always implies lock anyway
 * Note 2: xchg has side effect, so that attribute volatile is necessary,
 *	  but generally the primitive is invalid, *ptr is output argument. --ANK
 */
#define __xchg(x, ptr, size)						\
({									\
	__typeof(*(ptr)) __x = (x);					\
	switch (size) {							\
	case 1:								\
		asm volatile("xchgb %b0,%1"				\
			     : "=q" (__x)				\
			     : "m" (*__xg(ptr)), "0" (__x)		\
			     : "memory");				\
		break;							\
	case 2:								\
		asm volatile("xchgw %w0,%1"				\
			     : "=r" (__x)				\
			     : "m" (*__xg(ptr)), "0" (__x)		\
			     : "memory");				\
		break;							\
	case 4:								\
		asm volatile("xchgl %k0,%1"				\
			     : "=r" (__x)				\
			     : "m" (*__xg(ptr)), "0" (__x)		\
			     : "memory");				\
		break;							\
	case 8:								\
		asm volatile("xchgq %0,%1"				\
			     : "=r" (__x)				\
			     : "m" (*__xg(ptr)), "0" (__x)		\
			     : "memory");				\
		break;							\
	default:							\
		__xchg_wrong_size();					\
	}								\
	__x;								\
})

#define xchg(ptr, v)							\
	__xchg((v), (ptr), sizeof(*ptr))

#define __HAVE_ARCH_CMPXCHG 1

/*
 * Atomic compare and exchange.  Compare OLD with MEM, if identical,
 * store NEW in MEM.  Return the initial value in MEM.  Success is
 * indicated by comparing RETURN with OLD.
 */
#define __raw_cmpxchg(ptr, old, new, size, lock)			\
({									\
	__typeof__(*(ptr)) __ret;					\
	__typeof__(*(ptr)) __old = (old);				\
	__typeof__(*(ptr)) __new = (new);				\
	switch (size) {							\
	case 1:								\
		asm volatile(lock "cmpxchgb %b1,%2"			\
			     : "=a"(__ret)				\
			     : "q"(__new), "m"(*__xg(ptr)), "0"(__old)	\
			     : "memory");				\
		break;							\
	case 2:								\
		asm volatile(lock "cmpxchgw %w1,%2"			\
			     : "=a"(__ret)				\
			     : "r"(__new), "m"(*__xg(ptr)), "0"(__old)	\
			     : "memory");				\
		break;							\
	case 4:								\
		asm volatile(lock "cmpxchgl %k1,%2"			\
			     : "=a"(__ret)				\
			     : "r"(__new), "m"(*__xg(ptr)), "0"(__old)	\
			     : "memory");				\
		break;							\
	case 8:								\
		asm volatile(lock "cmpxchgq %1,%2"			\
			     : "=a"(__ret)				\
			     : "r"(__new), "m"(*__xg(ptr)), "0"(__old)	\
			     : "memory");				\
		break;							\
	default:							\
		__cmpxchg_wrong_size();					\
	}								\
	__ret;								\
})

#define __cmpxchg(ptr, old, new, size)					\
	__raw_cmpxchg((ptr), (old), (new), (size), LOCK_PREFIX)

#define __sync_cmpxchg(ptr, old, new, size)				\
	__raw_cmpxchg((ptr), (old), (new), (size), "lock; ")

#define __cmpxchg_local(ptr, old, new, size)				\
	__raw_cmpxchg((ptr), (old), (new), (size), "")

#define cmpxchg(ptr, old, new)						\
	__cmpxchg((ptr), (old), (new), sizeof(*ptr))

#define sync_cmpxchg(ptr, old, new)					\
	__sync_cmpxchg((ptr), (old), (new), sizeof(*ptr))

#define cmpxchg_local(ptr, old, new)					\
	__cmpxchg_local((ptr), (old), (new), sizeof(*ptr))

#define cmpxchg64(ptr, o, n)						\
({									\
	BUILD_BUG_ON(sizeof(*(ptr)) != 8);				\
	cmpxchg((ptr), (o), (n));					\
})

#define cmpxchg64_local(ptr, o, n)					\
({									\
	BUILD_BUG_ON(sizeof(*(ptr)) != 8);				\
	cmpxchg_local((ptr), (o), (n));					\
})

#endif /* _ASM_X86_CMPXCHG_64_H */