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Commit 1d4238c5 authored by Russell King's avatar Russell King
Browse files

ARM: spectre-v1: add array_index_mask_nospec() implementation 



Add an implementation of the array_index_mask_nospec() function for
mitigating Spectre variant 1 throughout the kernel.

Signed-off-by: default avatarRussell King <rmk+kernel@armlinux.org.uk>
Acked-by: default avatarMark Rutland <mark.rutland@arm.com>
Boot-tested-by: default avatarTony Lindgren <tony@atomide.com>
Reviewed-by: default avatarTony Lindgren <tony@atomide.com>
parent a78d1565

arch/arm/include/asm/barrier.h

+19 −0
Original line number Diff line number Diff line
@@ -76,6 +76,25 @@ extern void arm_heavy_mb(void); 
#define __smp_rmb()	__smp_mb()

#define __smp_wmb()	dmb(ishst)



#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__ */