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 
9 static 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 
26 static 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 
45 void __xchg_called_with_bad_pointer(void);
46 
47 static 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 
70 static 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 
81 static 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().  */
94 void __cmpxchg_called_with_bad_pointer(void);
95 
96 static 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 
122 static 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 #define cmpxchg64(ptr, o, n)	cmpxchg64_local((ptr), (o), (n))
145 
146 #endif /* __ARCH_SPARC64_CMPXCHG__ */
147