1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _TOOLS_LINUX_ASM_X86_ATOMIC_H
3 #define _TOOLS_LINUX_ASM_X86_ATOMIC_H
4
5 #include <linux/compiler.h>
6 #include <linux/types.h>
7 #include "rmwcc.h"
8
9 #define LOCK_PREFIX "\n\tlock; "
10
11 #include <asm/cmpxchg.h>
12
13 /*
14 * Atomic operations that C can't guarantee us. Useful for
15 * resource counting etc..
16 */
17
18 #define ATOMIC_INIT(i) { (i) }
19
20 /**
21 * atomic_read - read atomic variable
22 * @v: pointer of type atomic_t
23 *
24 * Atomically reads the value of @v.
25 */
atomic_read(const atomic_t * v)26 static inline int atomic_read(const atomic_t *v)
27 {
28 return READ_ONCE((v)->counter);
29 }
30
31 /**
32 * atomic_set - set atomic variable
33 * @v: pointer of type atomic_t
34 * @i: required value
35 *
36 * Atomically sets the value of @v to @i.
37 */
atomic_set(atomic_t * v,int i)38 static inline void atomic_set(atomic_t *v, int i)
39 {
40 v->counter = i;
41 }
42
43 /**
44 * atomic_inc - increment atomic variable
45 * @v: pointer of type atomic_t
46 *
47 * Atomically increments @v by 1.
48 */
atomic_inc(atomic_t * v)49 static inline void atomic_inc(atomic_t *v)
50 {
51 asm volatile(LOCK_PREFIX "incl %0"
52 : "+m" (v->counter));
53 }
54
55 /**
56 * atomic_dec_and_test - decrement and test
57 * @v: pointer of type atomic_t
58 *
59 * Atomically decrements @v by 1 and
60 * returns true if the result is 0, or false for all other
61 * cases.
62 */
atomic_dec_and_test(atomic_t * v)63 static inline int atomic_dec_and_test(atomic_t *v)
64 {
65 GEN_UNARY_RMWcc(LOCK_PREFIX "decl", v->counter, "%0", "e");
66 }
67
atomic_cmpxchg(atomic_t * v,int old,int new)68 static __always_inline int atomic_cmpxchg(atomic_t *v, int old, int new)
69 {
70 return cmpxchg(&v->counter, old, new);
71 }
72
73 #endif /* _TOOLS_LINUX_ASM_X86_ATOMIC_H */
74