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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 */
23extern void __xchg_called_with_bad_pointer(void);
24
25static inline
26unsigned 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 */
1/*
2 * Generic UP xchg and cmpxchg using interrupt disablement. Does not
3 * support SMP.
4 */
5
6#ifndef __ASM_GENERIC_CMPXCHG_H
7#define __ASM_GENERIC_CMPXCHG_H
8
9#ifdef CONFIG_SMP
10#error "Cannot use generic cmpxchg on SMP"
11#endif
12
13#include <linux/types.h>
14#include <linux/irqflags.h>
15
16#ifndef xchg
17
18/*
19 * This function doesn't exist, so you'll get a linker error if
20 * something tries to do an invalidly-sized xchg().
21 */
22extern void __xchg_called_with_bad_pointer(void);
23
24static inline
25unsigned long __xchg(unsigned long x, volatile void *ptr, int size)
26{
27 unsigned long ret, flags;
28
29 switch (size) {
30 case 1:
31#ifdef __xchg_u8
32 return __xchg_u8(x, ptr);
33#else
34 local_irq_save(flags);
35 ret = *(volatile u8 *)ptr;
36 *(volatile u8 *)ptr = x;
37 local_irq_restore(flags);
38 return ret;
39#endif /* __xchg_u8 */
40
41 case 2:
42#ifdef __xchg_u16
43 return __xchg_u16(x, ptr);
44#else
45 local_irq_save(flags);
46 ret = *(volatile u16 *)ptr;
47 *(volatile u16 *)ptr = x;
48 local_irq_restore(flags);
49 return ret;
50#endif /* __xchg_u16 */
51
52 case 4:
53#ifdef __xchg_u32
54 return __xchg_u32(x, ptr);
55#else
56 local_irq_save(flags);
57 ret = *(volatile u32 *)ptr;
58 *(volatile u32 *)ptr = x;
59 local_irq_restore(flags);
60 return ret;
61#endif /* __xchg_u32 */
62
63#ifdef CONFIG_64BIT
64 case 8:
65#ifdef __xchg_u64
66 return __xchg_u64(x, ptr);
67#else
68 local_irq_save(flags);
69 ret = *(volatile u64 *)ptr;
70 *(volatile u64 *)ptr = x;
71 local_irq_restore(flags);
72 return ret;
73#endif /* __xchg_u64 */
74#endif /* CONFIG_64BIT */
75
76 default:
77 __xchg_called_with_bad_pointer();
78 return x;
79 }
80}
81
82#define xchg(ptr, x) \
83 ((__typeof__(*(ptr))) __xchg((unsigned long)(x), (ptr), sizeof(*(ptr))))
84
85#endif /* xchg */
86
87/*
88 * Atomic compare and exchange.
89 *
90 * Do not define __HAVE_ARCH_CMPXCHG because we want to use it to check whether
91 * a cmpxchg primitive faster than repeated local irq save/restore exists.
92 */
93#include <asm-generic/cmpxchg-local.h>
94
95#define cmpxchg(ptr, o, n) cmpxchg_local((ptr), (o), (n))
96#define cmpxchg64(ptr, o, n) cmpxchg64_local((ptr), (o), (n))
97
98#endif /* __ASM_GENERIC_CMPXCHG_H */