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ARM: spectre-v1: add array_index_mask_nospec() implementation

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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 <rmk+kernel@armlinux.org.uk>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Boot-tested-by: Tony Lindgren <tony@atomide.com>
Reviewed-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: David A. Long <dave.long@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Russell King 2019-11-08 13:35:32 +01:00 • committed by Greg Kroah-Hartman
parent 8143a0f9c0
commit 3625082644
1 changed files with 21 additions and 0 deletions
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21
arch/arm/include/asm/barrier.h
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@ -108,5 +108,26 @@ 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
#include <asm-generic/barrier.h>
#endif /* !__ASSEMBLY__ */
#endif /* __ASM_BARRIER_H */