Messages in this thread Patch in this message | | | From | Alex Shi <> | Subject | [PATCH 24/29] arm64: Turn on KPTI only on CPUs that need it | Date | Wed, 28 Feb 2018 11:56:46 +0800 |
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From: Jayachandran C <jnair@caviumnetworks.com>
commit 0ba2e29c7fc1 upstream.
Whitelist Broadcom Vulcan/Cavium ThunderX2 processors in unmap_kernel_at_el0(). These CPUs are not vulnerable to CVE-2017-5754 and do not need KPTI when KASLR is off.
Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Jayachandran C <jnair@caviumnetworks.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Alex Shi <alex.shi@linaro.org> --- arch/arm64/kernel/cpufeature.c | 7 +++++++ 1 file changed, 7 insertions(+)
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index 6200b81..e62583d 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -766,6 +766,13 @@ static bool unmap_kernel_at_el0(const struct arm64_cpu_capabilities *entry, if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) return true; + /* Don't force KPTI for CPUs that are not vulnerable */ + switch (read_cpuid_id() & MIDR_CPU_MODEL_MASK) { + case MIDR_CAVIUM_THUNDERX2: + case MIDR_BRCM_VULCAN: + return false; + } + /* Defer to CPU feature registers */ return !cpuid_feature_extract_unsigned_field(pfr0, ID_AA64PFR0_CSV3_SHIFT); -- 2.7.4
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