arch/arm64/include/asm/cmpxchg.h

   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:     ldaxrb  %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                         : "cc", "memory");
  38                 break;
  39         case 2:
  40                 asm volatile("//        __xchg2\n"
  41                 "1:     ldaxrh  %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                         : "cc", "memory");
  47                 break;
  48         case 4:
  49                 asm volatile("//        __xchg4\n"
  50                 "1:     ldaxr   %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                         : "cc", "memory");
  56                 break;
  57         case 8:
  58                 asm volatile("//        __xchg8\n"
  59                 "1:     ldaxr   %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                         : "cc", "memory");
  65                 break;
  66         default:
  67                 BUILD_BUG();
  68         }
  69
  70         return ret;
  71 }
  72
  73 #define xchg(ptr,x) \
  74         ((__typeof__(*(ptr)))__xchg((unsigned long)(x),(ptr),sizeof(*(ptr))))
  75
  76 static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old,
  77                                       unsigned long new, int size)
  78 {
  79         unsigned long oldval = 0, res;
  80
  81         switch (size) {
  82         case 1:
  83                 do {
  84                         asm volatile("// __cmpxchg1\n"
  85                         "       ldxrb   %w1, %2\n"
  86                         "       mov     %w0, #0\n"
  87                         "       cmp     %w1, %w3\n"
  88                         "       b.ne    1f\n"
  89                         "       stxrb   %w0, %w4, %2\n"
  90                         "1:\n"
  91                                 : "=&r" (res), "=&r" (oldval), "+Q" (*(u8 *)ptr)
  92                                 : "Ir" (old), "r" (new)
  93                                 : "cc");
  94                 } while (res);
  95                 break;
  96
  97         case 2:
  98                 do {
  99                         asm volatile("// __cmpxchg2\n"
 100                         "       ldxrh   %w1, %2\n"
 101                         "       mov     %w0, #0\n"
 102                         "       cmp     %w1, %w3\n"
 103                         "       b.ne    1f\n"
 104                         "       stxrh   %w0, %w4, %2\n"
 105                         "1:\n"
 106                                 : "=&r" (res), "=&r" (oldval), "+Q" (*(u16 *)ptr)
 107                                 : "Ir" (old), "r" (new)
 108                                 : "cc");
 109                 } while (res);
 110                 break;
 111
 112         case 4:
 113                 do {
 114                         asm volatile("// __cmpxchg4\n"
 115                         "       ldxr    %w1, %2\n"
 116                         "       mov     %w0, #0\n"
 117                         "       cmp     %w1, %w3\n"
 118                         "       b.ne    1f\n"
 119                         "       stxr    %w0, %w4, %2\n"
 120                         "1:\n"
 121                                 : "=&r" (res), "=&r" (oldval), "+Q" (*(u32 *)ptr)
 122                                 : "Ir" (old), "r" (new)
 123                                 : "cc");
 124                 } while (res);
 125                 break;
 126
 127         case 8:
 128                 do {
 129                         asm volatile("// __cmpxchg8\n"
 130                         "       ldxr    %1, %2\n"
 131                         "       mov     %w0, #0\n"
 132                         "       cmp     %1, %3\n"
 133                         "       b.ne    1f\n"
 134                         "       stxr    %w0, %4, %2\n"
 135                         "1:\n"
 136                                 : "=&r" (res), "=&r" (oldval), "+Q" (*(u64 *)ptr)
 137                                 : "Ir" (old), "r" (new)
 138                                 : "cc");
 139                 } while (res);
 140                 break;
 141
 142         default:
 143                 BUILD_BUG();
 144         }
 145
 146         return oldval;
 147 }
 148
 149 static inline unsigned long __cmpxchg_mb(volatile void *ptr, unsigned long old,
 150                                          unsigned long new, int size)
 151 {
 152         unsigned long ret;
 153
 154         smp_mb();
 155         ret = __cmpxchg(ptr, old, new, size);
 156         smp_mb();
 157
 158         return ret;
 159 }
 160
 161 #define cmpxchg(ptr,o,n)                                                \
 162         ((__typeof__(*(ptr)))__cmpxchg_mb((ptr),                        \
 163                                           (unsigned long)(o),           \
 164                                           (unsigned long)(n),           \
 165                                           sizeof(*(ptr))))
 166
 167 #define cmpxchg_local(ptr,o,n)                                          \
 168         ((__typeof__(*(ptr)))__cmpxchg((ptr),                           \
 169                                        (unsigned long)(o),              \
 170                                        (unsigned long)(n),              \
 171                                        sizeof(*(ptr))))
 172
 173 #define cmpxchg64(ptr,o,n)              cmpxchg((ptr),(o),(n))
 174 #define cmpxchg64_local(ptr,o,n)        cmpxchg_local((ptr),(o),(n))
 175
 176 #endif  /* __ASM_CMPXCHG_H */