From bd4fb6d270bc423a9a4098108784f7f9254c4e6d Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Thu, 14 Jun 2018 11:21:34 +0100 Subject: arm64: Add support for SB barrier and patch in over DSB; ISB sequences We currently use a DSB; ISB sequence to inhibit speculation in set_fs(). Whilst this works for current CPUs, future CPUs may implement a new SB barrier instruction which acts as an architected speculation barrier. On CPUs that support it, patch in an SB; NOP sequence over the DSB; ISB sequence and advertise the presence of the new instruction to userspace. Signed-off-by: Will Deacon --- arch/arm64/include/uapi/asm/hwcap.h | 1 + 1 file changed, 1 insertion(+) (limited to 'arch/arm64/include/uapi') diff --git a/arch/arm64/include/uapi/asm/hwcap.h b/arch/arm64/include/uapi/asm/hwcap.h index 2bcd6e4f3474..7784f7cba16c 100644 --- a/arch/arm64/include/uapi/asm/hwcap.h +++ b/arch/arm64/include/uapi/asm/hwcap.h @@ -49,5 +49,6 @@ #define HWCAP_ILRCPC (1 << 26) #define HWCAP_FLAGM (1 << 27) #define HWCAP_SSBS (1 << 28) +#define HWCAP_SB (1 << 29) #endif /* _UAPI__ASM_HWCAP_H */ -- cgit v1.2.3