include/asm-generic/cmpxchg-local.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef __ASM_GENERIC_CMPXCHG_LOCAL_H
   3 #define __ASM_GENERIC_CMPXCHG_LOCAL_H
   4
   5 #include <linux/types.h>
   6 #include <linux/irqflags.h>
   7
   8 extern unsigned long wrong_size_cmpxchg(volatile void *ptr)
   9         __noreturn;
  10
  11 /*
  12  * Generic version of __cmpxchg_local (disables interrupts). Takes an unsigned
  13  * long parameter, supporting various types of architectures.
  14  */
  15 static inline unsigned long __cmpxchg_local_generic(volatile void *ptr,
  16                 unsigned long old, unsigned long new, int size)
  17 {
  18         unsigned long flags, prev;
  19
  20         /*
  21          * Sanity checking, compile-time.
  22          */
  23         if (size == 8 && sizeof(unsigned long) != 8)
  24                 wrong_size_cmpxchg(ptr);
  25
  26         raw_local_irq_save(flags);
  27         switch (size) {
  28         case 1: prev = *(u8 *)ptr;
  29                 if (prev == old)
  30                         *(u8 *)ptr = (u8)new;
  31                 break;
  32         case 2: prev = *(u16 *)ptr;
  33                 if (prev == old)
  34                         *(u16 *)ptr = (u16)new;
  35                 break;
  36         case 4: prev = *(u32 *)ptr;
  37                 if (prev == old)
  38                         *(u32 *)ptr = (u32)new;
  39                 break;
  40         case 8: prev = *(u64 *)ptr;
  41                 if (prev == old)
  42                         *(u64 *)ptr = (u64)new;
  43                 break;
  44         default:
  45                 wrong_size_cmpxchg(ptr);
  46         }
  47         raw_local_irq_restore(flags);
  48         return prev;
  49 }
  50
  51 /*
  52  * Generic version of __cmpxchg64_local. Takes an u64 parameter.
  53  */
  54 static inline u64 __cmpxchg64_local_generic(volatile void *ptr,
  55                 u64 old, u64 new)
  56 {
  57         u64 prev;
  58         unsigned long flags;
  59
  60         raw_local_irq_save(flags);
  61         prev = *(u64 *)ptr;
  62         if (prev == old)
  63                 *(u64 *)ptr = new;
  64         raw_local_irq_restore(flags);
  65         return prev;
  66 }
  67
  68 #endif