tools/arch/x86/include/asm/barrier.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _TOOLS_LINUX_ASM_X86_BARRIER_H
   3 #define _TOOLS_LINUX_ASM_X86_BARRIER_H
   4
   5 /*
   6  * Copied from the Linux kernel sources, and also moving code
   7  * out from tools/perf/perf-sys.h so as to make it be located
   8  * in a place similar as in the kernel sources.
   9  *
  10  * Force strict CPU ordering.
  11  * And yes, this is required on UP too when we're talking
  12  * to devices.
  13  */
  14
  15 #if defined(__i386__)
  16 /*
  17  * Some non-Intel clones support out of order store. wmb() ceases to be a
  18  * nop for these.
  19  */
  20 #define mb()    asm volatile("lock; addl $0,0(%%esp)" ::: "memory")
  21 #define rmb()   asm volatile("lock; addl $0,0(%%esp)" ::: "memory")
  22 #define wmb()   asm volatile("lock; addl $0,0(%%esp)" ::: "memory")
  23 #elif defined(__x86_64__)
  24 #define mb()    asm volatile("mfence":::"memory")
  25 #define rmb()   asm volatile("lfence":::"memory")
  26 #define wmb()   asm volatile("sfence" ::: "memory")
  27 #endif
  28
  29 #endif /* _TOOLS_LINUX_ASM_X86_BARRIER_H */