Commit 41a30537 authored Sep 06, 2016 by Will Deacon Committed by Amit Pundir Jan 16, 2017

BACKPORT: 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>

Bug: 31432001
Change-Id: I7f82b677a065ede302a763d39ffcc3fef83f8fbe
(cherry picked from commit f99a250cb6a3b301b101b4c0f5fcb80593bba6dc)
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>

parent f284b02c

arch/arm64/include/asm/assembler.h

+9 −0

Original line number	Diff line number	Diff line
		@@ -108,6 +108,15 @@
		dmb \opt
		.endm

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

		#define USER(l, x...) \
		9999: x; \
		.section __ex_table,"a"; \

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")