1 /* 2 * Based on arch/arm/include/asm/cmpxchg.h 3 * 4 * Copyright (C) 2012 ARM Ltd. 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License version 2 as 8 * published by the Free Software Foundation. 9 * 10 * This program is distributed in the hope that it will be useful, 11 * but WITHOUT ANY WARRANTY; without even the implied warranty of 12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 13 * GNU General Public License for more details. 14 * 15 * You should have received a copy of the GNU General Public License 16 * along with this program. If not, see <http://www.gnu.org/licenses/>. 17 */ 18 #ifndef __ASM_CMPXCHG_H 19 #define __ASM_CMPXCHG_H 20 21 #include <linux/bug.h> 22 23 #include <asm/barrier.h> 24 25 static inline unsigned long __xchg(unsigned long x, volatile void *ptr, int size) 26 { 27 unsigned long ret, tmp; 28 29 switch (size) { 30 case 1: 31 asm volatile("// __xchg1\n" 32 "1: ldxrb %w0, %2\n" 33 " stlxrb %w1, %w3, %2\n" 34 " cbnz %w1, 1b\n" 35 : "=&r" (ret), "=&r" (tmp), "+Q" (*(u8 *)ptr) 36 : "r" (x) 37 : "memory"); 38 break; 39 case 2: 40 asm volatile("// __xchg2\n" 41 "1: ldxrh %w0, %2\n" 42 " stlxrh %w1, %w3, %2\n" 43 " cbnz %w1, 1b\n" 44 : "=&r" (ret), "=&r" (tmp), "+Q" (*(u16 *)ptr) 45 : "r" (x) 46 : "memory"); 47 break; 48 case 4: 49 asm volatile("// __xchg4\n" 50 "1: ldxr %w0, %2\n" 51 " stlxr %w1, %w3, %2\n" 52 " cbnz %w1, 1b\n" 53 : "=&r" (ret), "=&r" (tmp), "+Q" (*(u32 *)ptr) 54 : "r" (x) 55 : "memory"); 56 break; 57 case 8: 58 asm volatile("// __xchg8\n" 59 "1: ldxr %0, %2\n" 60 " stlxr %w1, %3, %2\n" 61 " cbnz %w1, 1b\n" 62 : "=&r" (ret), "=&r" (tmp), "+Q" (*(u64 *)ptr) 63 : "r" (x) 64 : "memory"); 65 break; 66 default: 67 BUILD_BUG(); 68 } 69 70 smp_mb(); 71 return ret; 72 } 73 74 #define xchg(ptr,x) \ 75 ((__typeof__(*(ptr)))__xchg((unsigned long)(x),(ptr),sizeof(*(ptr)))) 76 77 static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old, 78 unsigned long new, int size) 79 { 80 unsigned long oldval = 0, res; 81 82 switch (size) { 83 case 1: 84 do { 85 asm volatile("// __cmpxchg1\n" 86 " ldxrb %w1, %2\n" 87 " mov %w0, #0\n" 88 " cmp %w1, %w3\n" 89 " b.ne 1f\n" 90 " stxrb %w0, %w4, %2\n" 91 "1:\n" 92 : "=&r" (res), "=&r" (oldval), "+Q" (*(u8 *)ptr) 93 : "Ir" (old), "r" (new) 94 : "cc"); 95 } while (res); 96 break; 97 98 case 2: 99 do { 100 asm volatile("// __cmpxchg2\n" 101 " ldxrh %w1, %2\n" 102 " mov %w0, #0\n" 103 " cmp %w1, %w3\n" 104 " b.ne 1f\n" 105 " stxrh %w0, %w4, %2\n" 106 "1:\n" 107 : "=&r" (res), "=&r" (oldval), "+Q" (*(u16 *)ptr) 108 : "Ir" (old), "r" (new) 109 : "cc"); 110 } while (res); 111 break; 112 113 case 4: 114 do { 115 asm volatile("// __cmpxchg4\n" 116 " ldxr %w1, %2\n" 117 " mov %w0, #0\n" 118 " cmp %w1, %w3\n" 119 " b.ne 1f\n" 120 " stxr %w0, %w4, %2\n" 121 "1:\n" 122 : "=&r" (res), "=&r" (oldval), "+Q" (*(u32 *)ptr) 123 : "Ir" (old), "r" (new) 124 : "cc"); 125 } while (res); 126 break; 127 128 case 8: 129 do { 130 asm volatile("// __cmpxchg8\n" 131 " ldxr %1, %2\n" 132 " mov %w0, #0\n" 133 " cmp %1, %3\n" 134 " b.ne 1f\n" 135 " stxr %w0, %4, %2\n" 136 "1:\n" 137 : "=&r" (res), "=&r" (oldval), "+Q" (*(u64 *)ptr) 138 : "Ir" (old), "r" (new) 139 : "cc"); 140 } while (res); 141 break; 142 143 default: 144 BUILD_BUG(); 145 } 146 147 return oldval; 148 } 149 150 static inline unsigned long __cmpxchg_mb(volatile void *ptr, unsigned long old, 151 unsigned long new, int size) 152 { 153 unsigned long ret; 154 155 smp_mb(); 156 ret = __cmpxchg(ptr, old, new, size); 157 smp_mb(); 158 159 return ret; 160 } 161 162 #define cmpxchg(ptr, o, n) \ 163 ({ \ 164 __typeof__(*(ptr)) __ret; \ 165 __ret = (__typeof__(*(ptr))) \ 166 __cmpxchg_mb((ptr), (unsigned long)(o), (unsigned long)(n), \ 167 sizeof(*(ptr))); \ 168 __ret; \ 169 }) 170 171 #define cmpxchg_local(ptr, o, n) \ 172 ({ \ 173 __typeof__(*(ptr)) __ret; \ 174 __ret = (__typeof__(*(ptr))) \ 175 __cmpxchg((ptr), (unsigned long)(o), \ 176 (unsigned long)(n), sizeof(*(ptr))); \ 177 __ret; \ 178 }) 179 180 #define cmpxchg64(ptr,o,n) cmpxchg((ptr),(o),(n)) 181 #define cmpxchg64_local(ptr,o,n) cmpxchg_local((ptr),(o),(n)) 182 183 #define cmpxchg64_relaxed(ptr,o,n) cmpxchg_local((ptr),(o),(n)) 184 185 #endif /* __ASM_CMPXCHG_H */ 186