From d71be2b6c0e19180b5f80a6d42039cc074a693a2 Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Fri, 15 Jun 2018 11:37:34 +0100 Subject: arm64: cpufeature: Detect SSBS and advertise to userspace Armv8.5 introduces a new PSTATE bit known as Speculative Store Bypass Safe (SSBS) which can be used as a mitigation against Spectre variant 4. Additionally, a CPU may provide instructions to manipulate PSTATE.SSBS directly, so that userspace can toggle the SSBS control without trapping to the kernel. This patch probes for the existence of SSBS and advertise the new instructions to userspace if they exist. Reviewed-by: Suzuki K Poulose Signed-off-by: Will Deacon Signed-off-by: Catalin Marinas --- 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 17c65c8f33cb..2bcd6e4f3474 100644 --- a/arch/arm64/include/uapi/asm/hwcap.h +++ b/arch/arm64/include/uapi/asm/hwcap.h @@ -48,5 +48,6 @@ #define HWCAP_USCAT (1 << 25) #define HWCAP_ILRCPC (1 << 26) #define HWCAP_FLAGM (1 << 27) +#define HWCAP_SSBS (1 << 28) #endif /* _UAPI__ASM_HWCAP_H */ -- cgit v1.2.3