This is a note to let you know that I've just added the patch titled
[Variant 3/Meltdown] arm64: entry: Reword comment about post_ttbr_update_workaround
to the 4.14-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-entry-reword-comment-about-post_ttbr_update_workaround.patch
and it can be found in the queue-4.14 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 Wed Feb 14 14:44:54 CET 2018
From: Will Deacon <will.deacon@xxxxxxx>
Date: Mon, 29 Jan 2018 11:59:58 +0000
Subject: [Variant 3/Meltdown] arm64: entry: Reword comment about post_ttbr_update_workaround
From: Will Deacon <will.deacon@xxxxxxx>
Commit f167211a93ac upstream.
We don't fully understand the Cavium ThunderX erratum, but it appears
that mapping the kernel as nG can lead to horrible consequences such as
attempting to execute userspace from kernel context. Since kpti isn't
enabled for these CPUs anyway, simplify the comment justifying the lack
of post_ttbr_update_workaround in the exception trampoline.
Signed-off-by: Will Deacon <will.deacon@xxxxxxx>
Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/arm64/kernel/entry.S | 13 +++----------
1 file changed, 3 insertions(+), 10 deletions(-)
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -962,16 +962,9 @@ alternative_else_nop_endif
orr \tmp, \tmp, #USER_ASID_FLAG
msr ttbr1_el1, \tmp
/*
- * We avoid running the post_ttbr_update_workaround here because the
- * user and kernel ASIDs don't have conflicting mappings, so any
- * "blessing" as described in:
- *
- * http://lkml.kernel.org/r/56BB848A.6060603@xxxxxxxxxxxxxxxxxx
- *
- * will not hurt correctness. Whilst this may partially defeat the
- * point of using split ASIDs in the first place, it avoids
- * the hit of invalidating the entire I-cache on every return to
- * userspace.
+ * We avoid running the post_ttbr_update_workaround here because
+ * it's only needed by Cavium ThunderX, which requires KPTI to be
+ * disabled.
*/
.endm
Patches currently in stable-queue which might be from will.deacon@xxxxxxx are
queue-4.14/arm64-make-user_ds-an-inclusive-limit.patch
queue-4.14/arm64-mm-remove-pre_ttbr0_update_workaround-for-falkor-erratum-e1003.patch
queue-4.14/arm64-uaccess-don-t-bother-eliding-access_ok-checks-in-__-get-put-_user.patch
queue-4.14/arm64-cpufeature-pass-capability-structure-to-enable-callback.patch
queue-4.14/arm64-uaccess-mask-__user-pointers-for-__arch_-clear-copy_-_user.patch
queue-4.14/arm64-mm-add-arm64_kernel_unmapped_at_el0-helper.patch
queue-4.14/arm64-entry-reword-comment-about-post_ttbr_update_workaround.patch
queue-4.14/arm64-kaslr-put-kernel-vectors-address-in-separate-data-page.patch
queue-4.14/arm-arm64-smccc-make-function-identifiers-an-unsigned-quantity.patch
queue-4.14/arm64-move-bp-hardening-to-check_and_switch_context.patch
queue-4.14/arm-arm64-kvm-advertise-smccc-v1.1.patch
queue-4.14/arm64-move-post_ttbr_update_workaround-to-c-code.patch
queue-4.14/arm64-turn-on-kpti-only-on-cpus-that-need-it.patch
queue-4.14/firmware-psci-expose-psci-conduit.patch
queue-4.14/arm64-force-kpti-to-be-disabled-on-cavium-thunderx.patch
queue-4.14/arm64-entry-apply-bp-hardening-for-high-priority-synchronous-exceptions.patch
queue-4.14/arm64-kpti-fix-the-interaction-between-asid-switching-and-software-pan.patch
queue-4.14/firmware-psci-expose-smccc-version-through-psci_ops.patch
queue-4.14/arm64-mm-permit-transitioning-from-global-to-non-global-without-bbm.patch
queue-4.14/arm64-mm-allocate-asids-in-pairs.patch
queue-4.14/arm64-tls-avoid-unconditional-zeroing-of-tpidrro_el0-for-native-tasks.patch
queue-4.14/arm64-use-ret-instruction-for-exiting-the-trampoline.patch
queue-4.14/arm64-futex-mask-__user-pointers-prior-to-dereference.patch
queue-4.14/arm64-entry-explicitly-pass-exception-level-to-kernel_ventry-macro.patch
queue-4.14/arm64-implement-branch-predictor-hardening-for-affected-cortex-a-cpus.patch
queue-4.14/arm64-kpti-make-use-of-ng-dependent-on-arm64_kernel_unmapped_at_el0.patch
queue-4.14/arm-arm64-kvm-add-psci_version-helper.patch
queue-4.14/arm64-kill-psci_get_version-as-a-variant-2-workaround.patch
queue-4.14/arm64-entry-ensure-branch-through-syscall-table-is-bounded-under-speculation.patch
queue-4.14/arm64-mm-use-non-global-mappings-for-kernel-space.patch
queue-4.14/arm64-entry-apply-bp-hardening-for-suspicious-interrupts-from-el0.patch
queue-4.14/arm64-capabilities-handle-duplicate-entries-for-a-capability.patch
queue-4.14/arm64-entry-hook-up-entry-trampoline-to-exception-vectors.patch
queue-4.14/arm64-branch-predictor-hardening-for-cavium-thunderx2.patch
queue-4.14/arm64-uaccess-prevent-speculative-use-of-the-current-addr_limit.patch
queue-4.14/.arm64-add-software-workaround-for-falkor-erratum-1041.patch.swp
queue-4.14/arm64-use-pointer-masking-to-limit-uaccess-speculation.patch
queue-4.14/arm64-add-arm_smccc_arch_workaround_1-bp-hardening-support.patch
queue-4.14/arm64-erratum-work-around-falkor-erratum-e1003-in-trampoline-code.patch
queue-4.14/arm64-mm-fix-and-re-enable-arm64_sw_ttbr0_pan.patch
queue-4.14/arm64-mm-invalidate-both-kernel-and-user-asids-when-performing-tlbi.patch
queue-4.14/drivers-firmware-expose-psci_get_version-through-psci_ops-structure.patch
queue-4.14/arm64-mm-rename-post_ttbr0_update_workaround.patch
queue-4.14/arm64-mm-map-entry-trampoline-into-trampoline-and-kernel-page-tables.patch
queue-4.14/arm-arm64-kvm-turn-kvm_psci_version-into-a-static-inline.patch
queue-4.14/arm-arm64-kvm-implement-psci-1.0-support.patch
queue-4.14/arm64-move-task_-definitions-to-asm-processor.h.patch
queue-4.14/arm64-kconfig-reword-unmap_kernel_at_el0-kconfig-entry.patch
queue-4.14/arm64-mm-move-asid-from-ttbr0-to-ttbr1.patch
queue-4.14/arm64-mm-introduce-ttbr_asid_mask-for-getting-at-the-asid-in-the-ttbr.patch
queue-4.14/arm64-kvm-add-smccc_arch_workaround_1-fast-handling.patch
queue-4.14/arm64-take-into-account-id_aa64pfr0_el1.csv3.patch
queue-4.14/arm64-cputype-add-missing-midr-values-for-cortex-a72-and-cortex-a75.patch
queue-4.14/arm64-kvm-report-smccc_arch_workaround_1-bp-hardening-support.patch
queue-4.14/arm64-barrier-add-csdb-macros-to-control-data-value-prediction.patch
queue-4.14/arm-arm64-smccc-implement-smccc-v1.1-inline-primitive.patch
queue-4.14/arm64-implement-branch-predictor-hardening-for-falkor.patch
queue-4.14/arm64-kconfig-add-config_unmap_kernel_at_el0.patch
queue-4.14/arm64-add-software-workaround-for-falkor-erratum-1041.patch
queue-4.14/arm64-idmap-use-awx-flags-for-.idmap.text-.pushsection-directives.patch
queue-4.14/arm64-run-enable-method-for-errata-work-arounds-on-late-cpus.patch
queue-4.14/arm64-mm-temporarily-disable-arm64_sw_ttbr0_pan.patch
queue-4.14/arm64-entry-add-exception-trampoline-page-for-exceptions-from-el0.patch
queue-4.14/arm64-kvm-make-psci_version-a-fast-path.patch
queue-4.14/arm64-cpufeature-__this_cpu_has_cap-shouldn-t-stop-early.patch
queue-4.14/arm64-implement-array_index_mask_nospec.patch
queue-4.14/arm64-kpti-add-enable-callback-to-remap-swapper-using-ng-mappings.patch
queue-4.14/arm-arm64-kvm-consolidate-the-psci-include-files.patch
queue-4.14/arm64-add-skeleton-to-harden-the-branch-predictor-against-aliasing-attacks.patch
queue-4.14/arm64-define-cputype-macros-for-falkor-cpu.patch
queue-4.14/arm64-cpu_errata-add-kryo-to-falkor-1003-errata.patch
queue-4.14/arm-arm64-kvm-add-smccc-accessors-to-psci-code.patch
queue-4.14/arm64-entry-add-fake-cpu-feature-for-unmapping-the-kernel-at-el0.patch
queue-4.14/arm64-kvm-use-per-cpu-vector-when-bp-hardening-is-enabled.patch
queue-4.14/arm64-cputype-add-midr-values-for-cavium-thunderx2-cpus.patch
queue-4.14/arm64-kvm-increment-pc-after-handling-an-smc-trap.patch