On Thu, Aug 29, 2019 at 05:03:46PM +0530, Viresh Kumar wrote:
> 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: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
Reviewed-by: Mark Rutland <mark.rutland@xxxxxxx> [v4.4 backport]
Mark.
> ---
> arch/arm64/include/asm/assembler.h | 7 +++++++
> arch/arm64/include/asm/barrier.h | 2 ++
> 2 files changed, 9 insertions(+)
>
> 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)
> --
> 2.21.0.rc0.269.g1a574e7a288b
>
