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[v4.4,V2,01/43] arm64: barrier: Add CSDB macros to control data-value prediction

Message ID fe952d04e88a653363f4ce73a8a7aedd2609c877.1562908074.git.viresh.kumar@linaro.org (mailing list archive)
State New, archived
Headers show
Series V4.4 backport of arm64 Spectre patches | expand

Commit Message

Viresh Kumar July 12, 2019, 5:27 a.m. UTC 
From: Will Deacon <will.deacon@arm.com>

commit 669474e772b952b14f4de4845a1558fd4c0414a4 upstream.

For CPUs capable of data value prediction, CSDB waits for any outstanding
predictions to architecturally resolve before allowing speculative execution
to continue. Provide macros to expose it to the arch code.

Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
 arch/arm64/include/asm/assembler.h | 7 +++++++
 arch/arm64/include/asm/barrier.h   | 2 ++
 2 files changed, 9 insertions(+)
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Patch

diff --git a/arch/arm64/include/asm/assembler.h b/arch/arm64/include/asm/assembler.h
index f68abb17aa4b..683c2875278f 100644
--- a/arch/arm64/include/asm/assembler.h
+++ b/arch/arm64/include/asm/assembler.h
@@ -95,6 +95,13 @@ 
 	dmb	\opt
 	.endm
 
+/*
+ * Value prediction barrier
+ */
+	.macro	csdb
+	hint	#20
+	.endm
+
 #define USER(l, x...)				\
 9999:	x;					\
 	.section __ex_table,"a";		\
diff --git a/arch/arm64/include/asm/barrier.h b/arch/arm64/include/asm/barrier.h
index f2d2c0bbe21b..574486634c62 100644
--- a/arch/arm64/include/asm/barrier.h
+++ b/arch/arm64/include/asm/barrier.h
@@ -28,6 +28,8 @@ 
 #define dmb(opt)	asm volatile("dmb " #opt : : : "memory")
 #define dsb(opt)	asm volatile("dsb " #opt : : : "memory")
 
+#define csdb()		asm volatile("hint #20" : : : "memory")
+
 #define mb()		dsb(sy)
 #define rmb()		dsb(ld)
 #define wmb()		dsb(st)