root/arch/parisc/include/asm/cmpxchg.h

INCLUDED FROM

DEFINITIONS

1. __xchg
2. __cmpxchg
3. __cmpxchg_local

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /*
   3  * forked from parisc asm/atomic.h which was:
   4  *      Copyright (C) 2000 Philipp Rumpf <prumpf@tux.org>
   5  *      Copyright (C) 2006 Kyle McMartin <kyle@parisc-linux.org>
   6  */
   7 
   8 #ifndef _ASM_PARISC_CMPXCHG_H_
   9 #define _ASM_PARISC_CMPXCHG_H_
  10 
  11 /* This should get optimized out since it's never called.
  12 ** Or get a link error if xchg is used "wrong".
  13 */
  14 extern void __xchg_called_with_bad_pointer(void);
  15 
  16 /* __xchg32/64 defined in arch/parisc/lib/bitops.c */
  17 extern unsigned long __xchg8(char, char *);
  18 extern unsigned long __xchg32(int, int *);
  19 #ifdef CONFIG_64BIT
  20 extern unsigned long __xchg64(unsigned long, unsigned long *);
  21 #endif
  22 
  23 /* optimizer better get rid of switch since size is a constant */
  24 static inline unsigned long
  25 __xchg(unsigned long x, __volatile__ void *ptr, int size)
  26 {
  27         switch (size) {
  28 #ifdef CONFIG_64BIT
  29         case 8: return __xchg64(x, (unsigned long *) ptr);
  30 #endif
  31         case 4: return __xchg32((int) x, (int *) ptr);
  32         case 1: return __xchg8((char) x, (char *) ptr);
  33         }
  34         __xchg_called_with_bad_pointer();
  35         return x;
  36 }
  37 
  38 /*
  39 ** REVISIT - Abandoned use of LDCW in xchg() for now:
  40 ** o need to test sizeof(*ptr) to avoid clearing adjacent bytes
  41 ** o and while we are at it, could CONFIG_64BIT code use LDCD too?
  42 **
  43 **      if (__builtin_constant_p(x) && (x == NULL))
  44 **              if (((unsigned long)p & 0xf) == 0)
  45 **                      return __ldcw(p);
  46 */
  47 #define xchg(ptr, x)                                                    \
  48 ({                                                                      \
  49         __typeof__(*(ptr)) __ret;                                       \
  50         __typeof__(*(ptr)) _x_ = (x);                                   \
  51         __ret = (__typeof__(*(ptr)))                                    \
  52                 __xchg((unsigned long)_x_, (ptr), sizeof(*(ptr)));      \
  53         __ret;                                                          \
  54 })
  55 
  56 /* bug catcher for when unsupported size is used - won't link */
  57 extern void __cmpxchg_called_with_bad_pointer(void);
  58 
  59 /* __cmpxchg_u32/u64 defined in arch/parisc/lib/bitops.c */
  60 extern unsigned long __cmpxchg_u32(volatile unsigned int *m, unsigned int old,
  61                                    unsigned int new_);
  62 extern u64 __cmpxchg_u64(volatile u64 *ptr, u64 old, u64 new_);
  63 
  64 /* don't worry...optimizer will get rid of most of this */
  65 static inline unsigned long
  66 __cmpxchg(volatile void *ptr, unsigned long old, unsigned long new_, int size)
  67 {
  68         switch (size) {
  69 #ifdef CONFIG_64BIT
  70         case 8: return __cmpxchg_u64((u64 *)ptr, old, new_);
  71 #endif
  72         case 4: return __cmpxchg_u32((unsigned int *)ptr,
  73                                      (unsigned int)old, (unsigned int)new_);
  74         }
  75         __cmpxchg_called_with_bad_pointer();
  76         return old;
  77 }
  78 
  79 #define cmpxchg(ptr, o, n)                                               \
  80 ({                                                                       \
  81         __typeof__(*(ptr)) _o_ = (o);                                    \
  82         __typeof__(*(ptr)) _n_ = (n);                                    \
  83         (__typeof__(*(ptr))) __cmpxchg((ptr), (unsigned long)_o_,        \
  84                                     (unsigned long)_n_, sizeof(*(ptr))); \
  85 })
  86 
  87 #include <asm-generic/cmpxchg-local.h>
  88 
  89 static inline unsigned long __cmpxchg_local(volatile void *ptr,
  90                                       unsigned long old,
  91                                       unsigned long new_, int size)
  92 {
  93         switch (size) {
  94 #ifdef CONFIG_64BIT
  95         case 8: return __cmpxchg_u64((u64 *)ptr, old, new_);
  96 #endif
  97         case 4: return __cmpxchg_u32(ptr, old, new_);
  98         default:
  99                 return __cmpxchg_local_generic(ptr, old, new_, size);
 100         }
 101 }
 102 
 103 /*
 104  * cmpxchg_local and cmpxchg64_local are atomic wrt current CPU. Always make
 105  * them available.
 106  */
 107 #define cmpxchg_local(ptr, o, n)                                        \
 108         ((__typeof__(*(ptr)))__cmpxchg_local((ptr), (unsigned long)(o), \
 109                         (unsigned long)(n), sizeof(*(ptr))))
 110 #ifdef CONFIG_64BIT
 111 #define cmpxchg64_local(ptr, o, n)                                      \
 112 ({                                                                      \
 113         BUILD_BUG_ON(sizeof(*(ptr)) != 8);                              \
 114         cmpxchg_local((ptr), (o), (n));                                 \
 115 })
 116 #else
 117 #define cmpxchg64_local(ptr, o, n) __cmpxchg64_local_generic((ptr), (o), (n))
 118 #endif
 119 
 120 #define cmpxchg64(ptr, o, n) __cmpxchg_u64(ptr, o, n)
 121 
 122 #endif /* _ASM_PARISC_CMPXCHG_H_ */