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Commit f99a250c authored Sep 06, 2016 by Will Deacon

arm64: barriers: introduce nops and __nops macros for NOP sequences



NOP sequences tend to get used for padding out alternative sections
and uarch-specific pipeline flushes in errata workarounds.

This patch adds macros for generating these sequences as both inline
asm blocks, but also as strings suitable for embedding in other asm
blocks directly.

Signed-off-by: Will Deacon <will.deacon@arm.com>

parent 8a71f0c6

arch/arm64/include/asm/assembler.h

+9 −0

Original line number	Diff line number	Diff line
		@@ -86,6 +86,15 @@
		dmb \opt
		.endm

		/*
		* NOP sequence
		*/
		.macro nops, num
		.rept \num
		nop
		.endr
		.endm

		/*
		* Emit an entry into the exception table
		*/

arch/arm64/include/asm/barrier.h

+3 −0

Original line number	Diff line number	Diff line
		@@ -20,6 +20,9 @@

		#ifndef __ASSEMBLY__

		#define __nops(n) ".rept " #n "\nnop\n.endr\n"
		#define nops(n) asm volatile(__nops(n))

		#define sev() asm volatile("sev" : : : "memory")
		#define wfe() asm volatile("wfe" : : : "memory")
		#define wfi() asm volatile("wfi" : : : "memory")