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authorDave Martin <Dave.Martin@arm.com>2017-12-14 14:03:44 +0000
committerWill Deacon <will.deacon@arm.com>2017-12-14 15:14:30 +0000
commit3fab39997a98b97138c886978af660c4f6c7e9e6 (patch)
treeeaf191d0def5b13d26c93f53365a52795e693f69 /arch/arm64/kernel/cpufeature.c
parent1d08a044cf12aee37dfd54837558e3295287b343 (diff)
downloadlwn-3fab39997a98b97138c886978af660c4f6c7e9e6.tar.gz
lwn-3fab39997a98b97138c886978af660c4f6c7e9e6.zip
arm64/sve: Report SVE to userspace via CPUID only if supported
Currently, the SVE field in ID_AA64PFR0_EL1 is visible unconditionally to userspace via the CPU ID register emulation, irrespective of the kernel config. This means that if a kernel configured with CONFIG_ARM64_SVE=n is run on SVE-capable hardware, userspace will see SVE reported as present in the ID regs even though the kernel forbids execution of SVE instructions. This patch makes the exposure of the SVE field in ID_AA64PFR0_EL1 conditional on CONFIG_ARM64_SVE=y. Since future architecture features are likely to encounter a similar requirement, this patch adds a suitable helper macros for use when declaring config-conditional ID register fields. Fixes: 43994d824e84 ("arm64/sve: Detect SVE and activate runtime support") Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com> Reported-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Dave Martin <Dave.Martin@arm.com> Cc: Suzuki Poulose <suzuki.poulose@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
Diffstat (limited to 'arch/arm64/kernel/cpufeature.c')
-rw-r--r--arch/arm64/kernel/cpufeature.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index c5ba0097887f..a73a5928f09b 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -145,7 +145,8 @@ static const struct arm64_ftr_bits ftr_id_aa64isar1[] = {
};
static const struct arm64_ftr_bits ftr_id_aa64pfr0[] = {
- ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR0_SVE_SHIFT, 4, 0),
+ ARM64_FTR_BITS(FTR_VISIBLE_IF_IS_ENABLED(CONFIG_ARM64_SVE),
+ FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR0_SVE_SHIFT, 4, 0),
ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR0_GIC_SHIFT, 4, 0),
S_ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR0_ASIMD_SHIFT, 4, ID_AA64PFR0_ASIMD_NI),
S_ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR0_FP_SHIFT, 4, ID_AA64PFR0_FP_NI),