arch/mips/include/asm/vdso/processor.h

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2 /*
   3  * Copyright (C) 2020 ARM Ltd.
   4  */
   5 #ifndef __ASM_VDSO_PROCESSOR_H
   6 #define __ASM_VDSO_PROCESSOR_H
   7
   8 #ifndef __ASSEMBLY__
   9
  10 #ifdef CONFIG_CPU_LOONGSON64
  11 /*
  12  * Loongson-3's SFB (Store-Fill-Buffer) may buffer writes indefinitely when a
  13  * tight read loop is executed, because reads take priority over writes & the
  14  * hardware (incorrectly) doesn't ensure that writes will eventually occur.
  15  *
  16  * Since spin loops of any kind should have a cpu_relax() in them, force an SFB
  17  * flush from cpu_relax() such that any pending writes will become visible as
  18  * expected.
  19  */
  20 #define cpu_relax()     smp_mb()
  21 #else
  22 #define cpu_relax()     barrier()
  23 #endif
  24
  25 #endif /* __ASSEMBLY__ */
  26
  27 #endif /* __ASM_VDSO_PROCESSOR_H */