From: will.deacon@arm.com (Will Deacon)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 2/6] arm64: barriers: introduce nops and __nops macros for NOP sequences
Date: Fri, 9 Sep 2016 12:16:01 +0100 [thread overview]
Message-ID: <1473419765-3437-3-git-send-email-will.deacon@arm.com> (raw)
In-Reply-To: <1473419765-3437-1-git-send-email-will.deacon@arm.com>
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>
---
arch/arm64/include/asm/assembler.h | 9 +++++++++
arch/arm64/include/asm/barrier.h | 3 +++
2 files changed, 12 insertions(+)
diff --git a/arch/arm64/include/asm/assembler.h b/arch/arm64/include/asm/assembler.h
index d5025c69ca81..43a75e2fe931 100644
--- a/arch/arm64/include/asm/assembler.h
+++ b/arch/arm64/include/asm/assembler.h
@@ -87,6 +87,15 @@
.endm
/*
+ * NOP sequence
+ */
+ .macro nops, num
+ .rept \num
+ nop
+ .endr
+ .endm
+
+/*
* Emit an entry into the exception table
*/
.macro _asm_extable, from, to
diff --git a/arch/arm64/include/asm/barrier.h b/arch/arm64/include/asm/barrier.h
index 4eea7f618dce..4e0497f581a0 100644
--- a/arch/arm64/include/asm/barrier.h
+++ b/arch/arm64/include/asm/barrier.h
@@ -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")
--
2.1.4
next prev parent reply other threads:[~2016-09-09 11:16 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-09 11:15 [PATCH 0/6] Further NOP/sysreg cleanups Will Deacon
2016-09-09 11:16 ` [PATCH 1/6] arm64: sysreg: replace open-coded mrs_s/msr_s with {read, write}_sysreg_s Will Deacon
2016-09-09 12:40 ` [PATCH 1/6] arm64: sysreg: replace open-coded mrs_s/msr_s with {read,write}_sysreg_s Mark Rutland
2016-09-09 11:16 ` Will Deacon [this message]
2016-09-09 11:16 ` [PATCH 3/6] arm64: lse: convert lse alternatives NOP padding to use __nops Will Deacon
2016-09-09 11:16 ` [PATCH 4/6] arm64: KVM: Move GIC accessors to arch_gicv3.h Will Deacon
2016-09-09 11:16 ` [PATCH 5/6] irqchip/gic-v3: Convert arm64 GIC accessors to {read, write}_sysreg_s Will Deacon
2016-09-09 11:16 ` [PATCH 6/6] irqchip/gic-v3: Use nops macro for Cavium ThunderX erratum 23154 Will Deacon
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