4.9-stable review patch. If anyone has any objections, please let me know.
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From: Mark Rutland mark.rutland@arm.com
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: Mark Rutland <mark.rutland@arm.com [v4.9 backport] Tested-by: Greg Hackmann ghackmann@google.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- 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)