[PATCH ARM32 v4.4 V2 20/47] ARM: spectre-v1: add array_index_mask_nospec() implementation
From: Viresh Kumar <viresh.kumar@linaro.org>
Date: 2019-08-01 08:20:29
Also in:
stable
Subsystem:
arm port, the rest · Maintainers:
Russell King, Linus Torvalds
From: Russell King <redacted> Commit 1d4238c56f9816ce0f9c8dbe42d7f2ad81cb6613 upstream. Add an implementation of the array_index_mask_nospec() function for mitigating Spectre variant 1 throughout the kernel. Signed-off-by: Russell King <redacted> Acked-by: Mark Rutland <mark.rutland@arm.com> Boot-tested-by: Tony Lindgren [off-list ref] Reviewed-by: Tony Lindgren <tony@atomide.com> Signed-off-by: David A. Long <redacted> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> --- arch/arm/include/asm/barrier.h | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+)
diff --git a/arch/arm/include/asm/barrier.h b/arch/arm/include/asm/barrier.h
index edd9e633a84b..744d70e1d202 100644
--- a/arch/arm/include/asm/barrier.h
+++ b/arch/arm/include/asm/barrier.h@@ -108,5 +108,24 @@ do { \ #define smp_mb__before_atomic() smp_mb() #define smp_mb__after_atomic() smp_mb() +#ifdef CONFIG_CPU_SPECTRE +static inline unsigned long array_index_mask_nospec(unsigned long idx, + unsigned long sz) +{ + unsigned long mask; + + asm volatile( + "cmp %1, %2\n" + " sbc %0, %1, %1\n" + CSDB + : "=r" (mask) + : "r" (idx), "Ir" (sz) + : "cc"); + + return mask; +} +#define array_index_mask_nospec array_index_mask_nospec +#endif + #endif /* !__ASSEMBLY__ */ #endif /* __ASM_BARRIER_H */
--
2.21.0.rc0.269.g1a574e7a288b
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