root/arch/x86/um/asm/barrier.h

INCLUDED FROM

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _ASM_UM_BARRIER_H_
   3 #define _ASM_UM_BARRIER_H_
   4 
   5 #include <asm/alternative.h>
   6 
   7 /*
   8  * Force strict CPU ordering.
   9  * And yes, this is required on UP too when we're talking
  10  * to devices.
  11  */
  12 #ifdef CONFIG_X86_32
  13 
  14 #define mb()    alternative("lock; addl $0,0(%%esp)", "mfence", X86_FEATURE_XMM2)
  15 #define rmb()   alternative("lock; addl $0,0(%%esp)", "lfence", X86_FEATURE_XMM2)
  16 #define wmb()   alternative("lock; addl $0,0(%%esp)", "sfence", X86_FEATURE_XMM)
  17 
  18 #else /* CONFIG_X86_32 */
  19 
  20 #define mb()    asm volatile("mfence" : : : "memory")
  21 #define rmb()   asm volatile("lfence" : : : "memory")
  22 #define wmb()   asm volatile("sfence" : : : "memory")
  23 
  24 #endif /* CONFIG_X86_32 */
  25 
  26 #include <asm-generic/barrier.h>
  27 
  28 #endif