xen/gntalloc: Replace UAPI 1-element array
[linux-2.6-microblaze.git] / include / asm-generic / cmpxchg.h
1 /* SPDX-License-Identifier: GPL-2.0 */
2 /*
3  * Generic UP xchg and cmpxchg using interrupt disablement.  Does not
4  * support SMP.
5  */
6
7 #ifndef __ASM_GENERIC_CMPXCHG_H
8 #define __ASM_GENERIC_CMPXCHG_H
9
10 #ifdef CONFIG_SMP
11 #error "Cannot use generic cmpxchg on SMP"
12 #endif
13
14 #include <linux/types.h>
15 #include <linux/irqflags.h>
16
17 /*
18  * This function doesn't exist, so you'll get a linker error if
19  * something tries to do an invalidly-sized xchg().
20  */
21 extern void __generic_xchg_called_with_bad_pointer(void);
22
23 static inline
24 unsigned long __generic_xchg(unsigned long x, volatile void *ptr, int size)
25 {
26         unsigned long ret, flags;
27
28         switch (size) {
29         case 1:
30 #ifdef __xchg_u8
31                 return __xchg_u8(x, ptr);
32 #else
33                 local_irq_save(flags);
34                 ret = *(volatile u8 *)ptr;
35                 *(volatile u8 *)ptr = (x & 0xffu);
36                 local_irq_restore(flags);
37                 return ret;
38 #endif /* __xchg_u8 */
39
40         case 2:
41 #ifdef __xchg_u16
42                 return __xchg_u16(x, ptr);
43 #else
44                 local_irq_save(flags);
45                 ret = *(volatile u16 *)ptr;
46                 *(volatile u16 *)ptr = (x & 0xffffu);
47                 local_irq_restore(flags);
48                 return ret;
49 #endif /* __xchg_u16 */
50
51         case 4:
52 #ifdef __xchg_u32
53                 return __xchg_u32(x, ptr);
54 #else
55                 local_irq_save(flags);
56                 ret = *(volatile u32 *)ptr;
57                 *(volatile u32 *)ptr = (x & 0xffffffffu);
58                 local_irq_restore(flags);
59                 return ret;
60 #endif /* __xchg_u32 */
61
62 #ifdef CONFIG_64BIT
63         case 8:
64 #ifdef __xchg_u64
65                 return __xchg_u64(x, ptr);
66 #else
67                 local_irq_save(flags);
68                 ret = *(volatile u64 *)ptr;
69                 *(volatile u64 *)ptr = x;
70                 local_irq_restore(flags);
71                 return ret;
72 #endif /* __xchg_u64 */
73 #endif /* CONFIG_64BIT */
74
75         default:
76                 __generic_xchg_called_with_bad_pointer();
77                 return x;
78         }
79 }
80
81 #define generic_xchg(ptr, x) ({                                                 \
82         ((__typeof__(*(ptr)))                                                   \
83                 __generic_xchg((unsigned long)(x), (ptr), sizeof(*(ptr))));     \
84 })
85
86 /*
87  * Atomic compare and exchange.
88  */
89 #include <asm-generic/cmpxchg-local.h>
90
91 #define generic_cmpxchg_local(ptr, o, n) ({                                     \
92         ((__typeof__(*(ptr)))__generic_cmpxchg_local((ptr), (unsigned long)(o), \
93                         (unsigned long)(n), sizeof(*(ptr))));                   \
94 })
95
96 #define generic_cmpxchg64_local(ptr, o, n) \
97         __generic_cmpxchg64_local((ptr), (o), (n))
98
99
100 #ifndef arch_xchg
101 #define arch_xchg               generic_xchg
102 #endif
103
104 #ifndef arch_cmpxchg_local
105 #define arch_cmpxchg_local      generic_cmpxchg_local
106 #endif
107
108 #ifndef arch_cmpxchg64_local
109 #define arch_cmpxchg64_local    generic_cmpxchg64_local
110 #endif
111
112 #define arch_cmpxchg            arch_cmpxchg_local
113 #define arch_cmpxchg64          arch_cmpxchg64_local
114
115 #endif /* __ASM_GENERIC_CMPXCHG_H */