[PATCH v2 3/4] tools headers UAPI: add cpu_relax() implementation for x86 and arm64
From: Yunsheng Lin <hidden>
Date: 2021-07-20 02:41:52
Also in:
lkml
Subsystem:
the rest · Maintainer:
Linus Torvalds
As x86 and arm64 is the two available systems that I can build and test the cpu_relax() implementation, so only add cpu_relax() implementation for x86 and arm64, other arches can be added easily when needed. Signed-off-by: Yunsheng Lin <redacted> --- tools/include/asm/processor.h | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+) create mode 100644 tools/include/asm/processor.h
diff --git a/tools/include/asm/processor.h b/tools/include/asm/processor.h
new file mode 100644
index 0000000..f9b3902
--- /dev/null
+++ b/tools/include/asm/processor.h@@ -0,0 +1,26 @@ +/* SPDX-License-Identifier: GPL-2.0 */ + +#ifndef __TOOLS_LINUX_ASM_PROCESSOR_H +#define __TOOLS_LINUX_ASM_PROCESSOR_H + +#if defined(__i386__) || defined(__x86_64__) +/* REP NOP (PAUSE) is a good thing to insert into busy-wait loops. */ +static __always_inline void rep_nop(void) +{ + asm volatile("rep; nop" ::: "memory"); +} + +static __always_inline void cpu_relax(void) +{ + rep_nop(); +} +#elif defined(__aarch64__) +static inline void cpu_relax(void) +{ + asm volatile("yield" ::: "memory"); +} +#else +#error "Architecture not supported" +#endif + +#endif
--
2.7.4