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