cmpxchg_64.h revision d550bbd40c0e10aefa05103dadbe0ae42e683707 
1/* 64-bit atomic xchg() and cmpxchg() definitions.
2 *
3 * Copyright (C) 1996, 1997, 2000 David S. Miller (davem@redhat.com)
4 */
5
6#ifndef __ARCH_SPARC64_CMPXCHG__
7#define __ARCH_SPARC64_CMPXCHG__
8
9static inline unsigned long xchg32(__volatile__ unsigned int *m, unsigned int val)
10{
11	unsigned long tmp1, tmp2;
12
13	__asm__ __volatile__(
14"	mov		%0, %1\n"
15"1:	lduw		[%4], %2\n"
16"	cas		[%4], %2, %0\n"
17"	cmp		%2, %0\n"
18"	bne,a,pn	%%icc, 1b\n"
19"	 mov		%1, %0\n"
20	: "=&r" (val), "=&r" (tmp1), "=&r" (tmp2)
21	: "0" (val), "r" (m)
22	: "cc", "memory");
23	return val;
24}
25
26static inline unsigned long xchg64(__volatile__ unsigned long *m, unsigned long val)
27{
28	unsigned long tmp1, tmp2;
29
30	__asm__ __volatile__(
31"	mov		%0, %1\n"
32"1:	ldx		[%4], %2\n"
33"	casx		[%4], %2, %0\n"
34"	cmp		%2, %0\n"
35"	bne,a,pn	%%xcc, 1b\n"
36"	 mov		%1, %0\n"
37	: "=&r" (val), "=&r" (tmp1), "=&r" (tmp2)
38	: "0" (val), "r" (m)
39	: "cc", "memory");
40	return val;
41}
42
43#define xchg(ptr,x) ((__typeof__(*(ptr)))__xchg((unsigned long)(x),(ptr),sizeof(*(ptr))))
44
45extern void __xchg_called_with_bad_pointer(void);
46
47static inline unsigned long __xchg(unsigned long x, __volatile__ void * ptr,
48				       int size)
49{
50	switch (size) {
51	case 4:
52		return xchg32(ptr, x);
53	case 8:
54		return xchg64(ptr, x);
55	}
56	__xchg_called_with_bad_pointer();
57	return x;
58}
59
60/*
61 * Atomic compare and exchange.  Compare OLD with MEM, if identical,
62 * store NEW in MEM.  Return the initial value in MEM.  Success is
63 * indicated by comparing RETURN with OLD.
64 */
65
66#include <asm-generic/cmpxchg-local.h>
67
68#define __HAVE_ARCH_CMPXCHG 1
69
70static inline unsigned long
71__cmpxchg_u32(volatile int *m, int old, int new)
72{
73	__asm__ __volatile__("cas [%2], %3, %0"
74			     : "=&r" (new)
75			     : "0" (new), "r" (m), "r" (old)
76			     : "memory");
77
78	return new;
79}
80
81static inline unsigned long
82__cmpxchg_u64(volatile long *m, unsigned long old, unsigned long new)
83{
84	__asm__ __volatile__("casx [%2], %3, %0"
85			     : "=&r" (new)
86			     : "0" (new), "r" (m), "r" (old)
87			     : "memory");
88
89	return new;
90}
91
92/* This function doesn't exist, so you'll get a linker error
93   if something tries to do an invalid cmpxchg().  */
94extern void __cmpxchg_called_with_bad_pointer(void);
95
96static inline unsigned long
97__cmpxchg(volatile void *ptr, unsigned long old, unsigned long new, int size)
98{
99	switch (size) {
100		case 4:
101			return __cmpxchg_u32(ptr, old, new);
102		case 8:
103			return __cmpxchg_u64(ptr, old, new);
104	}
105	__cmpxchg_called_with_bad_pointer();
106	return old;
107}
108
109#define cmpxchg(ptr,o,n)						 \
110  ({									 \
111     __typeof__(*(ptr)) _o_ = (o);					 \
112     __typeof__(*(ptr)) _n_ = (n);					 \
113     (__typeof__(*(ptr))) __cmpxchg((ptr), (unsigned long)_o_,		 \
114				    (unsigned long)_n_, sizeof(*(ptr))); \
115  })
116
117/*
118 * cmpxchg_local and cmpxchg64_local are atomic wrt current CPU. Always make
119 * them available.
120 */
121
122static inline unsigned long __cmpxchg_local(volatile void *ptr,
123				      unsigned long old,
124				      unsigned long new, int size)
125{
126	switch (size) {
127	case 4:
128	case 8:	return __cmpxchg(ptr, old, new, size);
129	default:
130		return __cmpxchg_local_generic(ptr, old, new, size);
131	}
132
133	return old;
134}
135
136#define cmpxchg_local(ptr, o, n)				  	\
137	((__typeof__(*(ptr)))__cmpxchg_local((ptr), (unsigned long)(o),	\
138			(unsigned long)(n), sizeof(*(ptr))))
139#define cmpxchg64_local(ptr, o, n)					\
140  ({									\
141	BUILD_BUG_ON(sizeof(*(ptr)) != 8);				\
142	cmpxchg_local((ptr), (o), (n));					\
143  })
144
145#endif /* __ARCH_SPARC64_CMPXCHG__ */
146