4.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Mark Rutland <mark.rutland@xxxxxxx>
From: Will Deacon <will.deacon@xxxxxxx>
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@xxxxxxx>
Signed-off-by: Will Deacon <will.deacon@xxxxxxx>
Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx>
Signed-off-by: Mark Rutland <mark.rutland@xxxxxxx [v4.9 backport]
Tested-by: Greg Hackmann <ghackmann@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/arm64/include/asm/assembler.h | 7 +++++++
arch/arm64/include/asm/barrier.h | 2 ++
2 files changed, 9 insertions(+)
--- a/arch/arm64/include/asm/assembler.h
+++ b/arch/arm64/include/asm/assembler.h
@@ -87,6 +87,13 @@
.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
@@ -31,6 +31,8 @@
#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)