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 4.15-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...
The filename of the patch is: arm64-entry-reword-comment-about-post_ttbr_update_workaround.patch and it can be found in the queue-4.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.
From foo@baz Tue Feb 13 17:25:10 CET 2018
From: Will Deacon will.deacon@arm.com 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@arm.com
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@arm.com Signed-off-by: Catalin Marinas catalin.marinas@arm.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- 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 @@ -1010,16 +1010,9 @@ 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@caviumnetworks.com - * - * 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@arm.com are
queue-4.15/arm64-make-user_ds-an-inclusive-limit.patch queue-4.15/arm64-mm-remove-pre_ttbr0_update_workaround-for-falkor-erratum-e1003.patch queue-4.15/arm64-uaccess-don-t-bother-eliding-access_ok-checks-in-__-get-put-_user.patch queue-4.15/arm64-cpufeature-pass-capability-structure-to-enable-callback.patch queue-4.15/arm64-uaccess-mask-__user-pointers-for-__arch_-clear-copy_-_user.patch queue-4.15/arm64-mm-add-arm64_kernel_unmapped_at_el0-helper.patch queue-4.15/arm64-entry-reword-comment-about-post_ttbr_update_workaround.patch queue-4.15/arm64-kaslr-put-kernel-vectors-address-in-separate-data-page.patch queue-4.15/arm-arm64-smccc-make-function-identifiers-an-unsigned-quantity.patch queue-4.15/arm64-move-bp-hardening-to-check_and_switch_context.patch queue-4.15/arm-arm64-kvm-advertise-smccc-v1.1.patch queue-4.15/arm64-move-post_ttbr_update_workaround-to-c-code.patch queue-4.15/arm64-turn-on-kpti-only-on-cpus-that-need-it.patch queue-4.15/firmware-psci-expose-psci-conduit.patch queue-4.15/arm64-force-kpti-to-be-disabled-on-cavium-thunderx.patch queue-4.15/arm64-entry-apply-bp-hardening-for-high-priority-synchronous-exceptions.patch queue-4.15/arm64-kpti-fix-the-interaction-between-asid-switching-and-software-pan.patch queue-4.15/firmware-psci-expose-smccc-version-through-psci_ops.patch queue-4.15/arm64-mm-permit-transitioning-from-global-to-non-global-without-bbm.patch queue-4.15/arm64-mm-allocate-asids-in-pairs.patch queue-4.15/arm64-tls-avoid-unconditional-zeroing-of-tpidrro_el0-for-native-tasks.patch queue-4.15/arm64-use-ret-instruction-for-exiting-the-trampoline.patch queue-4.15/arm64-futex-mask-__user-pointers-prior-to-dereference.patch queue-4.15/arm64-entry-explicitly-pass-exception-level-to-kernel_ventry-macro.patch queue-4.15/arm64-implement-branch-predictor-hardening-for-affected-cortex-a-cpus.patch queue-4.15/arm64-kpti-make-use-of-ng-dependent-on-arm64_kernel_unmapped_at_el0.patch queue-4.15/arm-arm64-kvm-add-psci_version-helper.patch queue-4.15/arm64-kill-psci_get_version-as-a-variant-2-workaround.patch queue-4.15/arm64-entry-ensure-branch-through-syscall-table-is-bounded-under-speculation.patch queue-4.15/arm64-mm-use-non-global-mappings-for-kernel-space.patch queue-4.15/arm64-entry-apply-bp-hardening-for-suspicious-interrupts-from-el0.patch queue-4.15/arm64-capabilities-handle-duplicate-entries-for-a-capability.patch queue-4.15/arm64-entry-hook-up-entry-trampoline-to-exception-vectors.patch queue-4.15/arm64-branch-predictor-hardening-for-cavium-thunderx2.patch queue-4.15/arm64-uaccess-prevent-speculative-use-of-the-current-addr_limit.patch queue-4.15/arm64-use-pointer-masking-to-limit-uaccess-speculation.patch queue-4.15/arm64-add-arm_smccc_arch_workaround_1-bp-hardening-support.patch queue-4.15/arm64-erratum-work-around-falkor-erratum-e1003-in-trampoline-code.patch queue-4.15/arm64-mm-fix-and-re-enable-arm64_sw_ttbr0_pan.patch queue-4.15/arm64-mm-invalidate-both-kernel-and-user-asids-when-performing-tlbi.patch queue-4.15/drivers-firmware-expose-psci_get_version-through-psci_ops-structure.patch queue-4.15/arm64-mm-rename-post_ttbr0_update_workaround.patch queue-4.15/arm64-mm-map-entry-trampoline-into-trampoline-and-kernel-page-tables.patch queue-4.15/arm-arm64-kvm-turn-kvm_psci_version-into-a-static-inline.patch queue-4.15/arm-arm64-kvm-implement-psci-1.0-support.patch queue-4.15/arm64-kconfig-reword-unmap_kernel_at_el0-kconfig-entry.patch queue-4.15/arm64-mm-move-asid-from-ttbr0-to-ttbr1.patch queue-4.15/arm64-mm-introduce-ttbr_asid_mask-for-getting-at-the-asid-in-the-ttbr.patch queue-4.15/arm64-kvm-add-smccc_arch_workaround_1-fast-handling.patch queue-4.15/arm64-take-into-account-id_aa64pfr0_el1.csv3.patch queue-4.15/arm64-cputype-add-missing-midr-values-for-cortex-a72-and-cortex-a75.patch queue-4.15/arm64-kvm-report-smccc_arch_workaround_1-bp-hardening-support.patch queue-4.15/arm64-barrier-add-csdb-macros-to-control-data-value-prediction.patch queue-4.15/arm-arm64-smccc-implement-smccc-v1.1-inline-primitive.patch queue-4.15/perf-arm_spe-fail-device-probe-when-arm64_kernel_unmapped_at_el0.patch queue-4.15/arm64-implement-branch-predictor-hardening-for-falkor.patch queue-4.15/arm64-kconfig-add-config_unmap_kernel_at_el0.patch queue-4.15/arm64-idmap-use-awx-flags-for-.idmap.text-.pushsection-directives.patch queue-4.15/arm64-run-enable-method-for-errata-work-arounds-on-late-cpus.patch queue-4.15/arm64-mm-temporarily-disable-arm64_sw_ttbr0_pan.patch queue-4.15/arm64-entry-add-exception-trampoline-page-for-exceptions-from-el0.patch queue-4.15/arm64-kvm-make-psci_version-a-fast-path.patch queue-4.15/arm64-cpufeature-__this_cpu_has_cap-shouldn-t-stop-early.patch queue-4.15/arm64-implement-array_index_mask_nospec.patch queue-4.15/arm64-kpti-add-enable-callback-to-remap-swapper-using-ng-mappings.patch queue-4.15/arm-arm64-kvm-consolidate-the-psci-include-files.patch queue-4.15/arm64-add-skeleton-to-harden-the-branch-predictor-against-aliasing-attacks.patch queue-4.15/arm64-cpu_errata-add-kryo-to-falkor-1003-errata.patch queue-4.15/arm-arm64-kvm-add-smccc-accessors-to-psci-code.patch queue-4.15/arm64-entry-add-fake-cpu-feature-for-unmapping-the-kernel-at-el0.patch queue-4.15/arm64-kvm-use-per-cpu-vector-when-bp-hardening-is-enabled.patch queue-4.15/arm64-cputype-add-midr-values-for-cavium-thunderx2-cpus.patch queue-4.15/arm64-kvm-increment-pc-after-handling-an-smc-trap.patch