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b2441318 | 1 | /* SPDX-License-Identifier: GPL-2.0 */ |
e9826380 JF |
2 | #ifndef ASM_X86_CMPXCHG_H |
3 | #define ASM_X86_CMPXCHG_H | |
4 | ||
61e2cd0a | 5 | #include <linux/compiler.h> |
cd4d09ec | 6 | #include <asm/cpufeatures.h> |
e9826380 JF |
7 | #include <asm/alternative.h> /* Provides LOCK_PREFIX */ |
8 | ||
61e2cd0a JF |
9 | /* |
10 | * Non-existant functions to indicate usage errors at link time | |
11 | * (or compile-time if the compiler implements __compiletime_error(). | |
12 | */ | |
13 | extern void __xchg_wrong_size(void) | |
14 | __compiletime_error("Bad argument size for xchg"); | |
15 | extern void __cmpxchg_wrong_size(void) | |
16 | __compiletime_error("Bad argument size for cmpxchg"); | |
17 | extern void __xadd_wrong_size(void) | |
18 | __compiletime_error("Bad argument size for xadd"); | |
3d94ae0c JF |
19 | extern void __add_wrong_size(void) |
20 | __compiletime_error("Bad argument size for add"); | |
e9826380 JF |
21 | |
22 | /* | |
23 | * Constants for operation sizes. On 32-bit, the 64-bit size it set to | |
24 | * -1 because sizeof will never return -1, thereby making those switch | |
25 | * case statements guaranteeed dead code which the compiler will | |
26 | * eliminate, and allowing the "missing symbol in the default case" to | |
27 | * indicate a usage error. | |
28 | */ | |
29 | #define __X86_CASE_B 1 | |
30 | #define __X86_CASE_W 2 | |
31 | #define __X86_CASE_L 4 | |
32 | #ifdef CONFIG_64BIT | |
33 | #define __X86_CASE_Q 8 | |
34 | #else | |
35 | #define __X86_CASE_Q -1 /* sizeof will never return -1 */ | |
36 | #endif | |
37 | ||
31a8394e JF |
38 | /* |
39 | * An exchange-type operation, which takes a value and a pointer, and | |
7f5281ae | 40 | * returns the old value. |
31a8394e JF |
41 | */ |
42 | #define __xchg_op(ptr, arg, op, lock) \ | |
43 | ({ \ | |
44 | __typeof__ (*(ptr)) __ret = (arg); \ | |
45 | switch (sizeof(*(ptr))) { \ | |
46 | case __X86_CASE_B: \ | |
47 | asm volatile (lock #op "b %b0, %1\n" \ | |
2ca052a3 | 48 | : "+q" (__ret), "+m" (*(ptr)) \ |
31a8394e JF |
49 | : : "memory", "cc"); \ |
50 | break; \ | |
51 | case __X86_CASE_W: \ | |
52 | asm volatile (lock #op "w %w0, %1\n" \ | |
53 | : "+r" (__ret), "+m" (*(ptr)) \ | |
54 | : : "memory", "cc"); \ | |
55 | break; \ | |
56 | case __X86_CASE_L: \ | |
57 | asm volatile (lock #op "l %0, %1\n" \ | |
58 | : "+r" (__ret), "+m" (*(ptr)) \ | |
59 | : : "memory", "cc"); \ | |
60 | break; \ | |
61 | case __X86_CASE_Q: \ | |
62 | asm volatile (lock #op "q %q0, %1\n" \ | |
63 | : "+r" (__ret), "+m" (*(ptr)) \ | |
64 | : : "memory", "cc"); \ | |
65 | break; \ | |
66 | default: \ | |
67 | __ ## op ## _wrong_size(); \ | |
68 | } \ | |
69 | __ret; \ | |
70 | }) | |
71 | ||
e9826380 JF |
72 | /* |
73 | * Note: no "lock" prefix even on SMP: xchg always implies lock anyway. | |
74 | * Since this is generally used to protect other memory information, we | |
75 | * use "asm volatile" and "memory" clobbers to prevent gcc from moving | |
76 | * information around. | |
77 | */ | |
31a8394e | 78 | #define xchg(ptr, v) __xchg_op((ptr), (v), xchg, "") |
e9826380 JF |
79 | |
80 | /* | |
81 | * Atomic compare and exchange. Compare OLD with MEM, if identical, | |
82 | * store NEW in MEM. Return the initial value in MEM. Success is | |
83 | * indicated by comparing RETURN with OLD. | |
84 | */ | |
85 | #define __raw_cmpxchg(ptr, old, new, size, lock) \ | |
86 | ({ \ | |
87 | __typeof__(*(ptr)) __ret; \ | |
88 | __typeof__(*(ptr)) __old = (old); \ | |
89 | __typeof__(*(ptr)) __new = (new); \ | |
90 | switch (size) { \ | |
91 | case __X86_CASE_B: \ | |
92 | { \ | |
93 | volatile u8 *__ptr = (volatile u8 *)(ptr); \ | |
94 | asm volatile(lock "cmpxchgb %2,%1" \ | |
95 | : "=a" (__ret), "+m" (*__ptr) \ | |
96 | : "q" (__new), "0" (__old) \ | |
97 | : "memory"); \ | |
98 | break; \ | |
99 | } \ | |
100 | case __X86_CASE_W: \ | |
101 | { \ | |
102 | volatile u16 *__ptr = (volatile u16 *)(ptr); \ | |
103 | asm volatile(lock "cmpxchgw %2,%1" \ | |
104 | : "=a" (__ret), "+m" (*__ptr) \ | |
105 | : "r" (__new), "0" (__old) \ | |
106 | : "memory"); \ | |
107 | break; \ | |
108 | } \ | |
109 | case __X86_CASE_L: \ | |
110 | { \ | |
111 | volatile u32 *__ptr = (volatile u32 *)(ptr); \ | |
112 | asm volatile(lock "cmpxchgl %2,%1" \ | |
113 | : "=a" (__ret), "+m" (*__ptr) \ | |
114 | : "r" (__new), "0" (__old) \ | |
115 | : "memory"); \ | |
116 | break; \ | |
117 | } \ | |
118 | case __X86_CASE_Q: \ | |
119 | { \ | |
120 | volatile u64 *__ptr = (volatile u64 *)(ptr); \ | |
121 | asm volatile(lock "cmpxchgq %2,%1" \ | |
122 | : "=a" (__ret), "+m" (*__ptr) \ | |
123 | : "r" (__new), "0" (__old) \ | |
124 | : "memory"); \ | |
125 | break; \ | |
126 | } \ | |
127 | default: \ | |
128 | __cmpxchg_wrong_size(); \ | |
129 | } \ | |
130 | __ret; \ | |
131 | }) | |
132 | ||
133 | #define __cmpxchg(ptr, old, new, size) \ | |
134 | __raw_cmpxchg((ptr), (old), (new), (size), LOCK_PREFIX) | |
135 | ||
136 | #define __sync_cmpxchg(ptr, old, new, size) \ | |
137 | __raw_cmpxchg((ptr), (old), (new), (size), "lock; ") | |
138 | ||
139 | #define __cmpxchg_local(ptr, old, new, size) \ | |
140 | __raw_cmpxchg((ptr), (old), (new), (size), "") | |
141 | ||
96a388de | 142 | #ifdef CONFIG_X86_32 |
a1ce3928 | 143 | # include <asm/cmpxchg_32.h> |
96a388de | 144 | #else |
a1ce3928 | 145 | # include <asm/cmpxchg_64.h> |
96a388de | 146 | #endif |
e9826380 | 147 | |
e9826380 | 148 | #define cmpxchg(ptr, old, new) \ |
fc395b92 | 149 | __cmpxchg(ptr, old, new, sizeof(*(ptr))) |
e9826380 JF |
150 | |
151 | #define sync_cmpxchg(ptr, old, new) \ | |
fc395b92 | 152 | __sync_cmpxchg(ptr, old, new, sizeof(*(ptr))) |
e9826380 JF |
153 | |
154 | #define cmpxchg_local(ptr, old, new) \ | |
fc395b92 | 155 | __cmpxchg_local(ptr, old, new, sizeof(*(ptr))) |
e9826380 | 156 | |
a9ebf306 PZ |
157 | |
158 | #define __raw_try_cmpxchg(_ptr, _pold, _new, size, lock) \ | |
159 | ({ \ | |
160 | bool success; \ | |
007d185b | 161 | __typeof__(_ptr) _old = (__typeof__(_ptr))(_pold); \ |
a9ebf306 PZ |
162 | __typeof__(*(_ptr)) __old = *_old; \ |
163 | __typeof__(*(_ptr)) __new = (_new); \ | |
164 | switch (size) { \ | |
165 | case __X86_CASE_B: \ | |
166 | { \ | |
167 | volatile u8 *__ptr = (volatile u8 *)(_ptr); \ | |
168 | asm volatile(lock "cmpxchgb %[new], %[ptr]" \ | |
169 | CC_SET(z) \ | |
170 | : CC_OUT(z) (success), \ | |
171 | [ptr] "+m" (*__ptr), \ | |
172 | [old] "+a" (__old) \ | |
173 | : [new] "q" (__new) \ | |
174 | : "memory"); \ | |
175 | break; \ | |
176 | } \ | |
177 | case __X86_CASE_W: \ | |
178 | { \ | |
179 | volatile u16 *__ptr = (volatile u16 *)(_ptr); \ | |
180 | asm volatile(lock "cmpxchgw %[new], %[ptr]" \ | |
181 | CC_SET(z) \ | |
182 | : CC_OUT(z) (success), \ | |
183 | [ptr] "+m" (*__ptr), \ | |
184 | [old] "+a" (__old) \ | |
185 | : [new] "r" (__new) \ | |
186 | : "memory"); \ | |
187 | break; \ | |
188 | } \ | |
189 | case __X86_CASE_L: \ | |
190 | { \ | |
191 | volatile u32 *__ptr = (volatile u32 *)(_ptr); \ | |
192 | asm volatile(lock "cmpxchgl %[new], %[ptr]" \ | |
193 | CC_SET(z) \ | |
194 | : CC_OUT(z) (success), \ | |
195 | [ptr] "+m" (*__ptr), \ | |
196 | [old] "+a" (__old) \ | |
197 | : [new] "r" (__new) \ | |
198 | : "memory"); \ | |
199 | break; \ | |
200 | } \ | |
201 | case __X86_CASE_Q: \ | |
202 | { \ | |
203 | volatile u64 *__ptr = (volatile u64 *)(_ptr); \ | |
204 | asm volatile(lock "cmpxchgq %[new], %[ptr]" \ | |
205 | CC_SET(z) \ | |
206 | : CC_OUT(z) (success), \ | |
207 | [ptr] "+m" (*__ptr), \ | |
208 | [old] "+a" (__old) \ | |
209 | : [new] "r" (__new) \ | |
210 | : "memory"); \ | |
211 | break; \ | |
212 | } \ | |
213 | default: \ | |
214 | __cmpxchg_wrong_size(); \ | |
215 | } \ | |
44fe8445 PZ |
216 | if (unlikely(!success)) \ |
217 | *_old = __old; \ | |
218 | likely(success); \ | |
a9ebf306 PZ |
219 | }) |
220 | ||
221 | #define __try_cmpxchg(ptr, pold, new, size) \ | |
222 | __raw_try_cmpxchg((ptr), (pold), (new), (size), LOCK_PREFIX) | |
223 | ||
224 | #define try_cmpxchg(ptr, pold, new) \ | |
225 | __try_cmpxchg((ptr), (pold), (new), sizeof(*(ptr))) | |
226 | ||
433b3520 JF |
227 | /* |
228 | * xadd() adds "inc" to "*ptr" and atomically returns the previous | |
229 | * value of "*ptr". | |
230 | * | |
231 | * xadd() is locked when multiple CPUs are online | |
433b3520 | 232 | */ |
31a8394e | 233 | #define __xadd(ptr, inc, lock) __xchg_op((ptr), (inc), xadd, lock) |
433b3520 | 234 | #define xadd(ptr, inc) __xadd((ptr), (inc), LOCK_PREFIX) |
3d94ae0c | 235 | |
cdcd6298 JB |
236 | #define __cmpxchg_double(pfx, p1, p2, o1, o2, n1, n2) \ |
237 | ({ \ | |
238 | bool __ret; \ | |
239 | __typeof__(*(p1)) __old1 = (o1), __new1 = (n1); \ | |
240 | __typeof__(*(p2)) __old2 = (o2), __new2 = (n2); \ | |
241 | BUILD_BUG_ON(sizeof(*(p1)) != sizeof(long)); \ | |
242 | BUILD_BUG_ON(sizeof(*(p2)) != sizeof(long)); \ | |
243 | VM_BUG_ON((unsigned long)(p1) % (2 * sizeof(long))); \ | |
244 | VM_BUG_ON((unsigned long)((p1) + 1) != (unsigned long)(p2)); \ | |
245 | asm volatile(pfx "cmpxchg%c4b %2; sete %0" \ | |
246 | : "=a" (__ret), "+d" (__old2), \ | |
247 | "+m" (*(p1)), "+m" (*(p2)) \ | |
248 | : "i" (2 * sizeof(long)), "a" (__old1), \ | |
249 | "b" (__new1), "c" (__new2)); \ | |
250 | __ret; \ | |
251 | }) | |
252 | ||
253 | #define cmpxchg_double(p1, p2, o1, o2, n1, n2) \ | |
254 | __cmpxchg_double(LOCK_PREFIX, p1, p2, o1, o2, n1, n2) | |
255 | ||
256 | #define cmpxchg_double_local(p1, p2, o1, o2, n1, n2) \ | |
257 | __cmpxchg_double(, p1, p2, o1, o2, n1, n2) | |
258 | ||
e9826380 | 259 | #endif /* ASM_X86_CMPXCHG_H */ |