This is a note to let you know that I've just added the patch titled
arm64: Turn on KPTI only on CPUs that need it
to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
arm64-turn-on-kpti-only-on-cpus-that-need-it.patch
and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Thu Apr 5 21:39:28 CEST 2018
From: Mark Rutland <mark.rutland@xxxxxxx>
Date: Tue, 3 Apr 2018 12:09:18 +0100
Subject: arm64: Turn on KPTI only on CPUs that need it
To: stable@xxxxxxxxxxxxxxx
Cc: mark.brown@xxxxxxxxxx, ard.biesheuvel@xxxxxxxxxx, marc.zyngier@xxxxxxx, will.deacon@xxxxxxx
Message-ID: <20180403110923.43575-23-mark.rutland@xxxxxxx>
From: Jayachandran C <jnair@xxxxxxxxxxxxxxxxxx>
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@xxxxxxx>
Signed-off-by: Jayachandran C <jnair@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx>
Signed-off-by: Will Deacon <will.deacon@xxxxxxx>
Signed-off-by: Alex Shi <alex.shi@xxxxxxxxxx> [v4.9 backport]
Signed-off-by: Mark Rutland <mark.rutland@xxxxxxx> [v4.9 backport]
Tested-by: Will Deacon <will.deacon@xxxxxxx>
Tested-by: Greg Hackmann <ghackmann@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/arm64/kernel/cpufeature.c | 7 +++++++
1 file changed, 7 insertions(+)
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -766,6 +766,13 @@ static bool unmap_kernel_at_el0(const st
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);
Patches currently in stable-queue which might be from mark.rutland@xxxxxxx are
queue-4.9/arm64-mm-add-arm64_kernel_unmapped_at_el0-helper.patch
queue-4.9/arm64-entry-reword-comment-about-post_ttbr_update_workaround.patch
queue-4.9/arm64-kaslr-put-kernel-vectors-address-in-separate-data-page.patch
queue-4.9/arm64-turn-on-kpti-only-on-cpus-that-need-it.patch
queue-4.9/arm64-force-kpti-to-be-disabled-on-cavium-thunderx.patch
queue-4.9/arm64-mm-allocate-asids-in-pairs.patch
queue-4.9/arm64-tls-avoid-unconditional-zeroing-of-tpidrro_el0-for-native-tasks.patch
queue-4.9/arm64-use-ret-instruction-for-exiting-the-trampoline.patch
queue-4.9/arm64-entry-explicitly-pass-exception-level-to-kernel_ventry-macro.patch
queue-4.9/arm64-kpti-make-use-of-ng-dependent-on-arm64_kernel_unmapped_at_el0.patch
queue-4.9/arm64-mm-use-non-global-mappings-for-kernel-space.patch
queue-4.9/arm64-capabilities-handle-duplicate-entries-for-a-capability.patch
queue-4.9/arm64-entry-hook-up-entry-trampoline-to-exception-vectors.patch
queue-4.9/arm64-mm-invalidate-both-kernel-and-user-asids-when-performing-tlbi.patch
queue-4.9/arm64-mm-map-entry-trampoline-into-trampoline-and-kernel-page-tables.patch
queue-4.9/module-extend-rodata-off-boot-cmdline-parameter-to-module-mappings.patch
queue-4.9/arm64-kconfig-reword-unmap_kernel_at_el0-kconfig-entry.patch
queue-4.9/arm64-mm-move-asid-from-ttbr0-to-ttbr1.patch
queue-4.9/arm64-allow-checking-of-a-cpu-local-erratum.patch
queue-4.9/arm64-take-into-account-id_aa64pfr0_el1.csv3.patch
queue-4.9/arm64-kconfig-add-config_unmap_kernel_at_el0.patch
queue-4.9/arm64-idmap-use-awx-flags-for-.idmap.text-.pushsection-directives.patch
queue-4.9/arm64-factor-out-entry-stack-manipulation.patch
queue-4.9/arm64-entry-add-exception-trampoline-page-for-exceptions-from-el0.patch
queue-4.9/arm64-kpti-add-enable-callback-to-remap-swapper-using-ng-mappings.patch
queue-4.9/arm64-entry-add-fake-cpu-feature-for-unmapping-the-kernel-at-el0.patch
queue-4.9/arm64-cputype-add-midr-values-for-cavium-thunderx2-cpus.patch