tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1/*
2 * Atomic xchg and cmpxchg operations.
3 *
4 * This file is subject to the terms and conditions of the GNU General Public
5 * License. See the file "COPYING" in the main directory of this archive
6 * for more details.
7 *
8 * Copyright (C) 2001 - 2005 Tensilica Inc.
9 */
10
11#ifndef _XTENSA_CMPXCHG_H
12#define _XTENSA_CMPXCHG_H
13
14#ifndef __ASSEMBLY__
15
16#include <linux/stringify.h>
17
18/*
19 * cmpxchg
20 */
21
22static inline unsigned long
23__cmpxchg_u32(volatile int *p, int old, int new)
24{
25 __asm__ __volatile__("rsil a15, "__stringify(LOCKLEVEL)"\n\t"
26 "l32i %0, %1, 0 \n\t"
27 "bne %0, %2, 1f \n\t"
28 "s32i %3, %1, 0 \n\t"
29 "1: \n\t"
30 "wsr a15, "__stringify(PS)" \n\t"
31 "rsync \n\t"
32 : "=&a" (old)
33 : "a" (p), "a" (old), "r" (new)
34 : "a15", "memory");
35 return old;
36}
37/* This function doesn't exist, so you'll get a linker error
38 * if something tries to do an invalid cmpxchg(). */
39
40extern void __cmpxchg_called_with_bad_pointer(void);
41
42static __inline__ unsigned long
43__cmpxchg(volatile void *ptr, unsigned long old, unsigned long new, int size)
44{
45 switch (size) {
46 case 4: return __cmpxchg_u32(ptr, old, new);
47 default: __cmpxchg_called_with_bad_pointer();
48 return old;
49 }
50}
51
52#define cmpxchg(ptr,o,n) \
53 ({ __typeof__(*(ptr)) _o_ = (o); \
54 __typeof__(*(ptr)) _n_ = (n); \
55 (__typeof__(*(ptr))) __cmpxchg((ptr), (unsigned long)_o_, \
56 (unsigned long)_n_, sizeof (*(ptr))); \
57 })
58
59#include <asm-generic/cmpxchg-local.h>
60
61static inline unsigned long __cmpxchg_local(volatile void *ptr,
62 unsigned long old,
63 unsigned long new, int size)
64{
65 switch (size) {
66 case 4:
67 return __cmpxchg_u32(ptr, old, new);
68 default:
69 return __cmpxchg_local_generic(ptr, old, new, size);
70 }
71
72 return old;
73}
74
75/*
76 * cmpxchg_local and cmpxchg64_local are atomic wrt current CPU. Always make
77 * them available.
78 */
79#define cmpxchg_local(ptr, o, n) \
80 ((__typeof__(*(ptr)))__cmpxchg_local_generic((ptr), (unsigned long)(o),\
81 (unsigned long)(n), sizeof(*(ptr))))
82#define cmpxchg64_local(ptr, o, n) __cmpxchg64_local_generic((ptr), (o), (n))
83
84/*
85 * xchg_u32
86 *
87 * Note that a15 is used here because the register allocation
88 * done by the compiler is not guaranteed and a window overflow
89 * may not occur between the rsil and wsr instructions. By using
90 * a15 in the rsil, the machine is guaranteed to be in a state
91 * where no register reference will cause an overflow.
92 */
93
94static inline unsigned long xchg_u32(volatile int * m, unsigned long val)
95{
96 unsigned long tmp;
97 __asm__ __volatile__("rsil a15, "__stringify(LOCKLEVEL)"\n\t"
98 "l32i %0, %1, 0 \n\t"
99 "s32i %2, %1, 0 \n\t"
100 "wsr a15, "__stringify(PS)" \n\t"
101 "rsync \n\t"
102 : "=&a" (tmp)
103 : "a" (m), "a" (val)
104 : "a15", "memory");
105 return tmp;
106}
107
108#define xchg(ptr,x) ((__typeof__(*(ptr)))__xchg((unsigned long)(x),(ptr),sizeof(*(ptr))))
109
110/*
111 * This only works if the compiler isn't horribly bad at optimizing.
112 * gcc-2.5.8 reportedly can't handle this, but I define that one to
113 * be dead anyway.
114 */
115
116extern void __xchg_called_with_bad_pointer(void);
117
118static __inline__ unsigned long
119__xchg(unsigned long x, volatile void * ptr, int size)
120{
121 switch (size) {
122 case 4:
123 return xchg_u32(ptr, x);
124 }
125 __xchg_called_with_bad_pointer();
126 return x;
127}
128
129#endif /* __ASSEMBLY__ */
130
131#endif /* _XTENSA_CMPXCHG_H */