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 #ifndef xchg
18
19 /*
20 * This function doesn't exist, so you'll get a linker error if
21 * something tries to do an invalidly-sized xchg().
22 */
23 extern void __xchg_called_with_bad_pointer(void);
24
25 static inline
__xchg(unsigned long x,volatile void * ptr,int size)26 unsigned long __xchg(unsigned long x, volatile void *ptr, int size)
27 {
28 unsigned long ret, flags;
29
30 switch (size) {
31 case 1:
32 #ifdef __xchg_u8
33 return __xchg_u8(x, ptr);
34 #else
35 local_irq_save(flags);
36 ret = *(volatile u8 *)ptr;
37 *(volatile u8 *)ptr = x;
38 local_irq_restore(flags);
39 return ret;
40 #endif /* __xchg_u8 */
41
42 case 2:
43 #ifdef __xchg_u16
44 return __xchg_u16(x, ptr);
45 #else
46 local_irq_save(flags);
47 ret = *(volatile u16 *)ptr;
48 *(volatile u16 *)ptr = x;
49 local_irq_restore(flags);
50 return ret;
51 #endif /* __xchg_u16 */
52
53 case 4:
54 #ifdef __xchg_u32
55 return __xchg_u32(x, ptr);
56 #else
57 local_irq_save(flags);
58 ret = *(volatile u32 *)ptr;
59 *(volatile u32 *)ptr = x;
60 local_irq_restore(flags);
61 return ret;
62 #endif /* __xchg_u32 */
63
64 #ifdef CONFIG_64BIT
65 case 8:
66 #ifdef __xchg_u64
67 return __xchg_u64(x, ptr);
68 #else
69 local_irq_save(flags);
70 ret = *(volatile u64 *)ptr;
71 *(volatile u64 *)ptr = x;
72 local_irq_restore(flags);
73 return ret;
74 #endif /* __xchg_u64 */
75 #endif /* CONFIG_64BIT */
76
77 default:
78 __xchg_called_with_bad_pointer();
79 return x;
80 }
81 }
82
83 #define xchg(ptr, x) ({ \
84 ((__typeof__(*(ptr))) \
85 __xchg((unsigned long)(x), (ptr), sizeof(*(ptr)))); \
86 })
87
88 #endif /* xchg */
89
90 /*
91 * Atomic compare and exchange.
92 */
93 #include <asm-generic/cmpxchg-local.h>
94
95 #ifndef cmpxchg_local
96 #define cmpxchg_local(ptr, o, n) ({ \
97 ((__typeof__(*(ptr)))__cmpxchg_local_generic((ptr), (unsigned long)(o),\
98 (unsigned long)(n), sizeof(*(ptr)))); \
99 })
100 #endif
101
102 #ifndef cmpxchg64_local
103 #define cmpxchg64_local(ptr, o, n) __cmpxchg64_local_generic((ptr), (o), (n))
104 #endif
105
106 #define cmpxchg(ptr, o, n) cmpxchg_local((ptr), (o), (n))
107 #define cmpxchg64(ptr, o, n) cmpxchg64_local((ptr), (o), (n))
108
109 #endif /* __ASM_GENERIC_CMPXCHG_H */
110