arch/x86/include/asm/cmpxchg_64.h

   1 #ifndef _ASM_X86_CMPXCHG_64_H
   2 #define _ASM_X86_CMPXCHG_64_H
   3
   4 #include <asm/alternative.h> /* Provides LOCK_PREFIX */
   5
   6 static inline void set_64bit(volatile u64 *ptr, u64 val)
   7 {
   8         *ptr = val;
   9 }
  10
  11 extern void __xchg_wrong_size(void);
  12 extern void __cmpxchg_wrong_size(void);
  13
  14 /*
  15  * Note: no "lock" prefix even on SMP: xchg always implies lock anyway.
  16  * Since this is generally used to protect other memory information, we
  17  * use "asm volatile" and "memory" clobbers to prevent gcc from moving
  18  * information around.
  19  */
  20 #define __xchg(x, ptr, size)                                            \
  21 ({                                                                      \
  22         __typeof(*(ptr)) __x = (x);                                     \
  23         switch (size) {                                                 \
  24         case 1:                                                         \
  25         {                                                               \
  26                 volatile u8 *__ptr = (volatile u8 *)(ptr);              \
  27                 asm volatile("xchgb %0,%1"                              \
  28                              : "=q" (__x), "+m" (*__ptr)                \
  29                              : "0" (__x)                                \
  30                              : "memory");                               \
  31                 break;                                                  \
  32         }                                                               \
  33         case 2:                                                         \
  34         {                                                               \
  35                 volatile u16 *__ptr = (volatile u16 *)(ptr);            \
  36                 asm volatile("xchgw %0,%1"                              \
  37                              : "=r" (__x), "+m" (*__ptr)                \
  38                              : "0" (__x)                                \
  39                              : "memory");                               \
  40                 break;                                                  \
  41         }                                                               \
  42         case 4:                                                         \
  43         {                                                               \
  44                 volatile u32 *__ptr = (volatile u32 *)(ptr);            \
  45                 asm volatile("xchgl %0,%1"                              \
  46                              : "=r" (__x), "+m" (*__ptr)                \
  47                              : "0" (__x)                                \
  48                              : "memory");                               \
  49                 break;                                                  \
  50         }                                                               \
  51         case 8:                                                         \
  52         {                                                               \
  53                 volatile u64 *__ptr = (volatile u64 *)(ptr);            \
  54                 asm volatile("xchgq %0,%1"                              \
  55                              : "=r" (__x), "+m" (*__ptr)                \
  56                              : "0" (__x)                                \
  57                              : "memory");                               \
  58                 break;                                                  \
  59         }                                                               \
  60         default:                                                        \
  61                 __xchg_wrong_size();                                    \
  62         }                                                               \
  63         __x;                                                            \
  64 })
  65
  66 #define xchg(ptr, v)                                                    \
  67         __xchg((v), (ptr), sizeof(*ptr))
  68
  69 #define __HAVE_ARCH_CMPXCHG 1
  70
  71 /*
  72  * Atomic compare and exchange.  Compare OLD with MEM, if identical,
  73  * store NEW in MEM.  Return the initial value in MEM.  Success is
  74  * indicated by comparing RETURN with OLD.
  75  */
  76 #define __raw_cmpxchg(ptr, old, new, size, lock)                        \
  77 ({                                                                      \
  78         __typeof__(*(ptr)) __ret;                                       \
  79         __typeof__(*(ptr)) __old = (old);                               \
  80         __typeof__(*(ptr)) __new = (new);                               \
  81         switch (size) {                                                 \
  82         case 1:                                                         \
  83         {                                                               \
  84                 volatile u8 *__ptr = (volatile u8 *)(ptr);              \
  85                 asm volatile(lock "cmpxchgb %2,%1"                      \
  86                              : "=a" (__ret), "+m" (*__ptr)              \
  87                              : "q" (__new), "0" (__old)                 \
  88                              : "memory");                               \
  89                 break;                                                  \
  90         }                                                               \
  91         case 2:                                                         \
  92         {                                                               \
  93                 volatile u16 *__ptr = (volatile u16 *)(ptr);            \
  94                 asm volatile(lock "cmpxchgw %2,%1"                      \
  95                              : "=a" (__ret), "+m" (*__ptr)              \
  96                              : "r" (__new), "0" (__old)                 \
  97                              : "memory");                               \
  98                 break;                                                  \
  99         }                                                               \
 100         case 4:                                                         \
 101         {                                                               \
 102                 volatile u32 *__ptr = (volatile u32 *)(ptr);            \
 103                 asm volatile(lock "cmpxchgl %2,%1"                      \
 104                              : "=a" (__ret), "+m" (*__ptr)              \
 105                              : "r" (__new), "0" (__old)                 \
 106                              : "memory");                               \
 107                 break;                                                  \
 108         }                                                               \
 109         case 8:                                                         \
 110         {                                                               \
 111                 volatile u64 *__ptr = (volatile u64 *)(ptr);            \
 112                 asm volatile(lock "cmpxchgq %2,%1"                      \
 113                              : "=a" (__ret), "+m" (*__ptr)              \
 114                              : "r" (__new), "0" (__old)                 \
 115                              : "memory");                               \
 116                 break;                                                  \
 117         }                                                               \
 118         default:                                                        \
 119                 __cmpxchg_wrong_size();                                 \
 120         }                                                               \
 121         __ret;                                                          \
 122 })
 123
 124 #define __cmpxchg(ptr, old, new, size)                                  \
 125         __raw_cmpxchg((ptr), (old), (new), (size), LOCK_PREFIX)
 126
 127 #define __sync_cmpxchg(ptr, old, new, size)                             \
 128         __raw_cmpxchg((ptr), (old), (new), (size), "lock; ")
 129
 130 #define __cmpxchg_local(ptr, old, new, size)                            \
 131         __raw_cmpxchg((ptr), (old), (new), (size), "")
 132
 133 #define cmpxchg(ptr, old, new)                                          \
 134         __cmpxchg((ptr), (old), (new), sizeof(*ptr))
 135
 136 #define sync_cmpxchg(ptr, old, new)                                     \
 137         __sync_cmpxchg((ptr), (old), (new), sizeof(*ptr))
 138
 139 #define cmpxchg_local(ptr, old, new)                                    \
 140         __cmpxchg_local((ptr), (old), (new), sizeof(*ptr))
 141
 142 #define cmpxchg64(ptr, o, n)                                            \
 143 ({                                                                      \
 144         BUILD_BUG_ON(sizeof(*(ptr)) != 8);                              \
 145         cmpxchg((ptr), (o), (n));                                       \
 146 })
 147
 148 #define cmpxchg64_local(ptr, o, n)                                      \
 149 ({                                                                      \
 150         BUILD_BUG_ON(sizeof(*(ptr)) != 8);                              \
 151         cmpxchg_local((ptr), (o), (n));                                 \
 152 })
 153
 154 #endif /* _ASM_X86_CMPXCHG_64_H */