From: Will Deacon <will.deacon@arm.com>
Date: Mon, 5 Feb 2018 15:34:16 +0000
Subject: arm64: barrier: Add CSDB macros to control data-value prediction
Git-commit: 669474e772b952b14f4de4845a1558fd4c0414a4
Patch-mainline: v4.16-rc1
References: bsc#1068032

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: Matthias Brugger <mbrugger@suse.com>
---
 arch/arm64/include/asm/assembler.h |    7 +++++++
 arch/arm64/include/asm/barrier.h   |    1 +
 2 files changed, 8 insertions(+)

--- a/arch/arm64/include/asm/assembler.h
+++ b/arch/arm64/include/asm/assembler.h
@@ -108,6 +108,13 @@
 	.endm
 
 /*
+ * Value prediction barrier
+ */
+	.macro	csdb
+	hint	#20
+	.endm
+
+/*
  * NOP sequence
  */
 	.macro	nops, num
--- a/arch/arm64/include/asm/barrier.h
+++ b/arch/arm64/include/asm/barrier.h
@@ -32,6 +32,7 @@
 #define dsb(opt)	asm volatile("dsb " #opt : : : "memory")
 
 #define psb_csync()	asm volatile("hint #17" : : : "memory")
+#define csdb()		asm volatile("hint #20" : : : "memory")
 
 #define mb()		dsb(sy)
 #define rmb()		dsb(ld)