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 == (u8)old)
30 			*(u8 *)ptr = (u8)new;
31 		break;
32 	case 2: prev = *(u16 *)ptr;
33 		if (prev == (u16)old)
34 			*(u16 *)ptr = (u16)new;
35 		break;
36 	case 4: prev = *(u32 *)ptr;
37 		if (prev == (u32)old)
38 			*(u32 *)ptr = (u32)new;
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