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Commit 0ba2e29c authored by Jayachandran C's avatar Jayachandran C Committed by Catalin Marinas
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arm64: Turn on KPTI only on CPUs that need it 



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: default avatarWill Deacon <will.deacon@arm.com>
Signed-off-by: default avatarJayachandran C <jnair@caviumnetworks.com>
Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent f3d795d9

arch/arm64/kernel/cpufeature.c

+7 −0
Original line number Diff line number Diff line
@@ -868,6 +868,13 @@ 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);