tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1#ifndef _ASM_X86_ATOMIC_H
2#define _ASM_X86_ATOMIC_H
3
4#include <linux/compiler.h>
5#include <linux/types.h>
6#include <asm/processor.h>
7#include <asm/alternative.h>
8#include <asm/cmpxchg.h>
9
10/*
11 * Atomic operations that C can't guarantee us. Useful for
12 * resource counting etc..
13 */
14
15#define ATOMIC_INIT(i) { (i) }
16
17/**
18 * atomic_read - read atomic variable
19 * @v: pointer of type atomic_t
20 *
21 * Atomically reads the value of @v.
22 */
23static inline int atomic_read(const atomic_t *v)
24{
25 return (*(volatile int *)&(v)->counter);
26}
27
28/**
29 * atomic_set - set atomic variable
30 * @v: pointer of type atomic_t
31 * @i: required value
32 *
33 * Atomically sets the value of @v to @i.
34 */
35static inline void atomic_set(atomic_t *v, int i)
36{
37 v->counter = i;
38}
39
40/**
41 * atomic_add - add integer to atomic variable
42 * @i: integer value to add
43 * @v: pointer of type atomic_t
44 *
45 * Atomically adds @i to @v.
46 */
47static inline void atomic_add(int i, atomic_t *v)
48{
49 asm volatile(LOCK_PREFIX "addl %1,%0"
50 : "+m" (v->counter)
51 : "ir" (i));
52}
53
54/**
55 * atomic_sub - subtract integer from atomic variable
56 * @i: integer value to subtract
57 * @v: pointer of type atomic_t
58 *
59 * Atomically subtracts @i from @v.
60 */
61static inline void atomic_sub(int i, atomic_t *v)
62{
63 asm volatile(LOCK_PREFIX "subl %1,%0"
64 : "+m" (v->counter)
65 : "ir" (i));
66}
67
68/**
69 * atomic_sub_and_test - subtract value from variable and test result
70 * @i: integer value to subtract
71 * @v: pointer of type atomic_t
72 *
73 * Atomically subtracts @i from @v and returns
74 * true if the result is zero, or false for all
75 * other cases.
76 */
77static inline int atomic_sub_and_test(int i, atomic_t *v)
78{
79 unsigned char c;
80
81 asm volatile(LOCK_PREFIX "subl %2,%0; sete %1"
82 : "+m" (v->counter), "=qm" (c)
83 : "ir" (i) : "memory");
84 return c;
85}
86
87/**
88 * atomic_inc - increment atomic variable
89 * @v: pointer of type atomic_t
90 *
91 * Atomically increments @v by 1.
92 */
93static inline void atomic_inc(atomic_t *v)
94{
95 asm volatile(LOCK_PREFIX "incl %0"
96 : "+m" (v->counter));
97}
98
99/**
100 * atomic_dec - decrement atomic variable
101 * @v: pointer of type atomic_t
102 *
103 * Atomically decrements @v by 1.
104 */
105static inline void atomic_dec(atomic_t *v)
106{
107 asm volatile(LOCK_PREFIX "decl %0"
108 : "+m" (v->counter));
109}
110
111/**
112 * atomic_dec_and_test - decrement and test
113 * @v: pointer of type atomic_t
114 *
115 * Atomically decrements @v by 1 and
116 * returns true if the result is 0, or false for all other
117 * cases.
118 */
119static inline int atomic_dec_and_test(atomic_t *v)
120{
121 unsigned char c;
122
123 asm volatile(LOCK_PREFIX "decl %0; sete %1"
124 : "+m" (v->counter), "=qm" (c)
125 : : "memory");
126 return c != 0;
127}
128
129/**
130 * atomic_inc_and_test - increment and test
131 * @v: pointer of type atomic_t
132 *
133 * Atomically increments @v by 1
134 * and returns true if the result is zero, or false for all
135 * other cases.
136 */
137static inline int atomic_inc_and_test(atomic_t *v)
138{
139 unsigned char c;
140
141 asm volatile(LOCK_PREFIX "incl %0; sete %1"
142 : "+m" (v->counter), "=qm" (c)
143 : : "memory");
144 return c != 0;
145}
146
147/**
148 * atomic_add_negative - add and test if negative
149 * @i: integer value to add
150 * @v: pointer of type atomic_t
151 *
152 * Atomically adds @i to @v and returns true
153 * if the result is negative, or false when
154 * result is greater than or equal to zero.
155 */
156static inline int atomic_add_negative(int i, atomic_t *v)
157{
158 unsigned char c;
159
160 asm volatile(LOCK_PREFIX "addl %2,%0; sets %1"
161 : "+m" (v->counter), "=qm" (c)
162 : "ir" (i) : "memory");
163 return c;
164}
165
166/**
167 * atomic_add_return - add integer and return
168 * @i: integer value to add
169 * @v: pointer of type atomic_t
170 *
171 * Atomically adds @i to @v and returns @i + @v
172 */
173static inline int atomic_add_return(int i, atomic_t *v)
174{
175#ifdef CONFIG_M386
176 int __i;
177 unsigned long flags;
178 if (unlikely(boot_cpu_data.x86 <= 3))
179 goto no_xadd;
180#endif
181 /* Modern 486+ processor */
182 return i + xadd(&v->counter, i);
183
184#ifdef CONFIG_M386
185no_xadd: /* Legacy 386 processor */
186 raw_local_irq_save(flags);
187 __i = atomic_read(v);
188 atomic_set(v, i + __i);
189 raw_local_irq_restore(flags);
190 return i + __i;
191#endif
192}
193
194/**
195 * atomic_sub_return - subtract integer and return
196 * @v: pointer of type atomic_t
197 * @i: integer value to subtract
198 *
199 * Atomically subtracts @i from @v and returns @v - @i
200 */
201static inline int atomic_sub_return(int i, atomic_t *v)
202{
203 return atomic_add_return(-i, v);
204}
205
206#define atomic_inc_return(v) (atomic_add_return(1, v))
207#define atomic_dec_return(v) (atomic_sub_return(1, v))
208
209static inline int atomic_cmpxchg(atomic_t *v, int old, int new)
210{
211 return cmpxchg(&v->counter, old, new);
212}
213
214static inline int atomic_xchg(atomic_t *v, int new)
215{
216 return xchg(&v->counter, new);
217}
218
219/**
220 * __atomic_add_unless - add unless the number is already a given value
221 * @v: pointer of type atomic_t
222 * @a: the amount to add to v...
223 * @u: ...unless v is equal to u.
224 *
225 * Atomically adds @a to @v, so long as @v was not already @u.
226 * Returns the old value of @v.
227 */
228static inline int __atomic_add_unless(atomic_t *v, int a, int u)
229{
230 int c, old;
231 c = atomic_read(v);
232 for (;;) {
233 if (unlikely(c == (u)))
234 break;
235 old = atomic_cmpxchg((v), c, c + (a));
236 if (likely(old == c))
237 break;
238 c = old;
239 }
240 return c;
241}
242
243/**
244 * atomic_inc_short - increment of a short integer
245 * @v: pointer to type int
246 *
247 * Atomically adds 1 to @v
248 * Returns the new value of @u
249 */
250static inline short int atomic_inc_short(short int *v)
251{
252 asm(LOCK_PREFIX "addw $1, %0" : "+m" (*v));
253 return *v;
254}
255
256#ifdef CONFIG_X86_64
257/**
258 * atomic_or_long - OR of two long integers
259 * @v1: pointer to type unsigned long
260 * @v2: pointer to type unsigned long
261 *
262 * Atomically ORs @v1 and @v2
263 * Returns the result of the OR
264 */
265static inline void atomic_or_long(unsigned long *v1, unsigned long v2)
266{
267 asm(LOCK_PREFIX "orq %1, %0" : "+m" (*v1) : "r" (v2));
268}
269#endif
270
271/* These are x86-specific, used by some header files */
272#define atomic_clear_mask(mask, addr) \
273 asm volatile(LOCK_PREFIX "andl %0,%1" \
274 : : "r" (~(mask)), "m" (*(addr)) : "memory")
275
276#define atomic_set_mask(mask, addr) \
277 asm volatile(LOCK_PREFIX "orl %0,%1" \
278 : : "r" ((unsigned)(mask)), "m" (*(addr)) \
279 : "memory")
280
281/* Atomic operations are already serializing on x86 */
282#define smp_mb__before_atomic_dec() barrier()
283#define smp_mb__after_atomic_dec() barrier()
284#define smp_mb__before_atomic_inc() barrier()
285#define smp_mb__after_atomic_inc() barrier()
286
287#ifdef CONFIG_X86_32
288# include <asm/atomic64_32.h>
289#else
290# include <asm/atomic64_64.h>
291#endif
292
293#endif /* _ASM_X86_ATOMIC_H */