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

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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>
This commit is contained in:
Will Deacon 2016-09-06 16:40:23 +01:00 • committed by Amit Pundir
parent e58abcea50
commit ce7bd06ee7
2 changed files with 12 additions and 0 deletions
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9
arch/arm64/include/asm/assembler.h
View file

@ -98,6 +98,15 @@
dmb \opt
.endm
/*
* NOP sequence
*/
.macro nops, num
.rept \num
nop
.endr
.endm
/*
* Emit an entry into the exception table
*/

3
arch/arm64/include/asm/barrier.h
View file

@ -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")