include/asm-x86/cmpxchg_64.h

   1 #ifndef __ASM_CMPXCHG_H
   2 #define __ASM_CMPXCHG_H
   3
   4 #include <asm/alternative.h> /* Provides LOCK_PREFIX */
   5
   6 #define xchg(ptr, v) ((__typeof__(*(ptr)))__xchg((unsigned long)(v), \
   7                                                  (ptr), sizeof(*(ptr))))
   8
   9 #define __xg(x) ((volatile long *)(x))
  10
  11 static inline void set_64bit(volatile unsigned long *ptr, unsigned long val)
  12 {
  13         *ptr = val;
  14 }
  15
  16 #define _set_64bit set_64bit
  17
  18 /*
  19  * Note: no "lock" prefix even on SMP: xchg always implies lock anyway
  20  * Note 2: xchg has side effect, so that attribute volatile is necessary,
  21  *        but generally the primitive is invalid, *ptr is output argument. --ANK
  22  */
  23 static inline unsigned long __xchg(unsigned long x, volatile void *ptr,
  24                                    int size)
  25 {
  26         switch (size) {
  27         case 1:
  28                 asm volatile("xchgb %b0,%1"
  29                              : "=q" (x)
  30                              : "m" (*__xg(ptr)), "0" (x)
  31                              : "memory");
  32                 break;
  33         case 2:
  34                 asm volatile("xchgw %w0,%1"
  35                              : "=r" (x)
  36                              : "m" (*__xg(ptr)), "0" (x)
  37                              : "memory");
  38                 break;
  39         case 4:
  40                 asm volatile("xchgl %k0,%1"
  41                              : "=r" (x)
  42                              : "m" (*__xg(ptr)), "0" (x)
  43                              : "memory");
  44                 break;
  45         case 8:
  46                 asm volatile("xchgq %0,%1"
  47                              : "=r" (x)
  48                              : "m" (*__xg(ptr)), "0" (x)
  49                              : "memory");
  50                 break;
  51         }
  52         return x;
  53 }
  54
  55 /*
  56  * Atomic compare and exchange.  Compare OLD with MEM, if identical,
  57  * store NEW in MEM.  Return the initial value in MEM.  Success is
  58  * indicated by comparing RETURN with OLD.
  59  */
  60
  61 #define __HAVE_ARCH_CMPXCHG 1
  62
  63 static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old,
  64                                       unsigned long new, int size)
  65 {
  66         unsigned long prev;
  67         switch (size) {
  68         case 1:
  69                 asm volatile(LOCK_PREFIX "cmpxchgb %b1,%2"
  70                              : "=a"(prev)
  71                              : "q"(new), "m"(*__xg(ptr)), "0"(old)
  72                              : "memory");
  73                 return prev;
  74         case 2:
  75                 asm volatile(LOCK_PREFIX "cmpxchgw %w1,%2"
  76                              : "=a"(prev)
  77                              : "r"(new), "m"(*__xg(ptr)), "0"(old)
  78                              : "memory");
  79                 return prev;
  80         case 4:
  81                 asm volatile(LOCK_PREFIX "cmpxchgl %k1,%2"
  82                              : "=a"(prev)
  83                              : "r"(new), "m"(*__xg(ptr)), "0"(old)
  84                              : "memory");
  85                 return prev;
  86         case 8:
  87                 asm volatile(LOCK_PREFIX "cmpxchgq %1,%2"
  88                              : "=a"(prev)
  89                              : "r"(new), "m"(*__xg(ptr)), "0"(old)
  90                              : "memory");
  91                 return prev;
  92         }
  93         return old;
  94 }
  95
  96 static inline unsigned long __cmpxchg_local(volatile void *ptr,
  97                                             unsigned long old,
  98                                             unsigned long new, int size)
  99 {
 100         unsigned long prev;
 101         switch (size) {
 102         case 1:
 103                 asm volatile("cmpxchgb %b1,%2"
 104                              : "=a"(prev)
 105                              : "q"(new), "m"(*__xg(ptr)), "0"(old)
 106                              : "memory");
 107                 return prev;
 108         case 2:
 109                 asm volatile("cmpxchgw %w1,%2"
 110                              : "=a"(prev)
 111                              : "r"(new), "m"(*__xg(ptr)), "0"(old)
 112                              : "memory");
 113                 return prev;
 114         case 4:
 115                 asm volatile("cmpxchgl %k1,%2"
 116                              : "=a"(prev)
 117                              : "r"(new), "m"(*__xg(ptr)), "0"(old)
 118                              : "memory");
 119                 return prev;
 120         case 8:
 121                 asm volatile("cmpxchgq %1,%2"
 122                              : "=a"(prev)
 123                              : "r"(new), "m"(*__xg(ptr)), "0"(old)
 124                              : "memory");
 125                 return prev;
 126         }
 127         return old;
 128 }
 129
 130 #define cmpxchg(ptr, o, n)                                              \
 131         ((__typeof__(*(ptr)))__cmpxchg((ptr), (unsigned long)(o),       \
 132                                        (unsigned long)(n), sizeof(*(ptr))))
 133 #define cmpxchg64(ptr, o, n)                                            \
 134 ({                                                                      \
 135         BUILD_BUG_ON(sizeof(*(ptr)) != 8);                              \
 136         cmpxchg((ptr), (o), (n));                                       \
 137 })
 138 #define cmpxchg_local(ptr, o, n)                                        \
 139         ((__typeof__(*(ptr)))__cmpxchg_local((ptr), (unsigned long)(o), \
 140                                              (unsigned long)(n),        \
 141                                              sizeof(*(ptr))))
 142 #define cmpxchg64_local(ptr, o, n)                                      \
 143 ({                                                                      \
 144         BUILD_BUG_ON(sizeof(*(ptr)) != 8);                              \
 145         cmpxchg_local((ptr), (o), (n));                                 \
 146 })
 147
 148 #endif