include/asm-x86_64/cmpxchg.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),(ptr),sizeof(*(ptr))))
   7
   8 #define __xg(x) ((volatile long *)(x))
   9
  10 static inline void set_64bit(volatile unsigned long *ptr, unsigned long val)
  11 {
  12         *ptr = val;
  13 }
  14
  15 #define _set_64bit set_64bit
  16
  17 /*
  18  * Note: no "lock" prefix even on SMP: xchg always implies lock anyway
  19  * Note 2: xchg has side effect, so that attribute volatile is necessary,
  20  *        but generally the primitive is invalid, *ptr is output argument. --ANK
  21  */
  22 static inline unsigned long __xchg(unsigned long x, volatile void * ptr, int size)
  23 {
  24         switch (size) {
  25                 case 1:
  26                         __asm__ __volatile__("xchgb %b0,%1"
  27                                 :"=q" (x)
  28                                 :"m" (*__xg(ptr)), "0" (x)
  29                                 :"memory");
  30                         break;
  31                 case 2:
  32                         __asm__ __volatile__("xchgw %w0,%1"
  33                                 :"=r" (x)
  34                                 :"m" (*__xg(ptr)), "0" (x)
  35                                 :"memory");
  36                         break;
  37                 case 4:
  38                         __asm__ __volatile__("xchgl %k0,%1"
  39                                 :"=r" (x)
  40                                 :"m" (*__xg(ptr)), "0" (x)
  41                                 :"memory");
  42                         break;
  43                 case 8:
  44                         __asm__ __volatile__("xchgq %0,%1"
  45                                 :"=r" (x)
  46                                 :"m" (*__xg(ptr)), "0" (x)
  47                                 :"memory");
  48                         break;
  49         }
  50         return x;
  51 }
  52
  53 /*
  54  * Atomic compare and exchange.  Compare OLD with MEM, if identical,
  55  * store NEW in MEM.  Return the initial value in MEM.  Success is
  56  * indicated by comparing RETURN with OLD.
  57  */
  58
  59 #define __HAVE_ARCH_CMPXCHG 1
  60
  61 static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old,
  62                                       unsigned long new, int size)
  63 {
  64         unsigned long prev;
  65         switch (size) {
  66         case 1:
  67                 __asm__ __volatile__(LOCK_PREFIX "cmpxchgb %b1,%2"
  68                                      : "=a"(prev)
  69                                      : "q"(new), "m"(*__xg(ptr)), "0"(old)
  70                                      : "memory");
  71                 return prev;
  72         case 2:
  73                 __asm__ __volatile__(LOCK_PREFIX "cmpxchgw %w1,%2"
  74                                      : "=a"(prev)
  75                                      : "r"(new), "m"(*__xg(ptr)), "0"(old)
  76                                      : "memory");
  77                 return prev;
  78         case 4:
  79                 __asm__ __volatile__(LOCK_PREFIX "cmpxchgl %k1,%2"
  80                                      : "=a"(prev)
  81                                      : "r"(new), "m"(*__xg(ptr)), "0"(old)
  82                                      : "memory");
  83                 return prev;
  84         case 8:
  85                 __asm__ __volatile__(LOCK_PREFIX "cmpxchgq %1,%2"
  86                                      : "=a"(prev)
  87                                      : "r"(new), "m"(*__xg(ptr)), "0"(old)
  88                                      : "memory");
  89                 return prev;
  90         }
  91         return old;
  92 }
  93
  94 static inline unsigned long __cmpxchg_local(volatile void *ptr,
  95                         unsigned long old, unsigned long new, int size)
  96 {
  97         unsigned long prev;
  98         switch (size) {
  99         case 1:
 100                 __asm__ __volatile__("cmpxchgb %b1,%2"
 101                                      : "=a"(prev)
 102                                      : "q"(new), "m"(*__xg(ptr)), "0"(old)
 103                                      : "memory");
 104                 return prev;
 105         case 2:
 106                 __asm__ __volatile__("cmpxchgw %w1,%2"
 107                                      : "=a"(prev)
 108                                      : "r"(new), "m"(*__xg(ptr)), "0"(old)
 109                                      : "memory");
 110                 return prev;
 111         case 4:
 112                 __asm__ __volatile__("cmpxchgl %k1,%2"
 113                                      : "=a"(prev)
 114                                      : "r"(new), "m"(*__xg(ptr)), "0"(old)
 115                                      : "memory");
 116                 return prev;
 117         case 8:
 118                 __asm__ __volatile__("cmpxchgq %1,%2"
 119                                      : "=a"(prev)
 120                                      : "r"(new), "m"(*__xg(ptr)), "0"(old)
 121                                      : "memory");
 122                 return prev;
 123         }
 124         return old;
 125 }
 126
 127 #define cmpxchg(ptr,o,n)\
 128         ((__typeof__(*(ptr)))__cmpxchg((ptr),(unsigned long)(o),\
 129                                         (unsigned long)(n),sizeof(*(ptr))))
 130 #define cmpxchg_local(ptr,o,n)\
 131         ((__typeof__(*(ptr)))__cmpxchg((ptr),(unsigned long)(o),\
 132                                         (unsigned long)(n),sizeof(*(ptr))))
 133
 134 #endif