1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef __ASM_GENERIC_CMPXCHG_LOCAL_H
3 #define __ASM_GENERIC_CMPXCHG_LOCAL_H
4
5 #include <linux/types.h>
6 #include <linux/irqflags.h>
7
8 extern unsigned long wrong_size_cmpxchg(volatile void *ptr)
9 __noreturn;
10
11 /*
12 * Generic version of __cmpxchg_local (disables interrupts). Takes an unsigned
13 * long parameter, supporting various types of architectures.
14 */
15 static inline unsigned long __generic_cmpxchg_local(volatile void *ptr,
16 unsigned long old, unsigned long new, int size)
17 {
18 unsigned long flags, prev;
19
20 /*
21 * Sanity checking, compile-time.
22 */
23 if (size == 8 && sizeof(unsigned long) != 8)
24 wrong_size_cmpxchg(ptr);
25
26 raw_local_irq_save(flags);
27 switch (size) {
28 case 1: prev = *(u8 *)ptr;
29 if (prev == (old & 0xffu))
30 *(u8 *)ptr = (new & 0xffu);
31 break;
32 case 2: prev = *(u16 *)ptr;
33 if (prev == (old & 0xffffu))
34 *(u16 *)ptr = (new & 0xffffu);
35 break;
36 case 4: prev = *(u32 *)ptr;
37 if (prev == (old & 0xffffffffu))
38 *(u32 *)ptr = (new & 0xffffffffu);
39 break;
40 case 8: prev = *(u64 *)ptr;
41 if (prev == old)
42 *(u64 *)ptr = (u64)new;
43 break;
44 default:
45 wrong_size_cmpxchg(ptr);
46 }
47 raw_local_irq_restore(flags);
48 return prev;
49 }
50
51 /*
52 * Generic version of __cmpxchg64_local. Takes an u64 parameter.
53 */
54 static inline u64 __generic_cmpxchg64_local(volatile void *ptr,
55 u64 old, u64 new)
56 {
57 u64 prev;
58 unsigned long flags;
59
60 raw_local_irq_save(flags);
61 prev = *(u64 *)ptr;
62 if (prev == old)
63 *(u64 *)ptr = new;
64 raw_local_irq_restore(flags);
65 return prev;
66 }
67
68 #endif
69
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