This is a note to let you know that I've just added the patch titled
arm64: mm: Map entry trampoline into trampoline and kernel page tables
to the 4.9-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-mm-map-entry-trampoline-into-trampoline-and-kernel-page-tables.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@vger.kernel.org know about it.
From foo@baz Thu Apr 5 21:39:27 CEST 2018
From: Mark Rutland mark.rutland@arm.com Date: Tue, 3 Apr 2018 12:09:05 +0100 Subject: arm64: mm: Map entry trampoline into trampoline and kernel page tables To: stable@vger.kernel.org Cc: mark.brown@linaro.org, ard.biesheuvel@linaro.org, marc.zyngier@arm.com, will.deacon@arm.com Message-ID: 20180403110923.43575-10-mark.rutland@arm.com
From: Will Deacon will.deacon@arm.com
commit 51a0048beb44 upstream.
The exception entry trampoline needs to be mapped at the same virtual address in both the trampoline page table (which maps nothing else) and also the kernel page table, so that we can swizzle TTBR1_EL1 on exceptions from and return to EL0.
This patch maps the trampoline at a fixed virtual address in the fixmap area of the kernel virtual address space, which allows the kernel proper to be randomized with respect to the trampoline when KASLR is enabled.
Reviewed-by: Mark Rutland mark.rutland@arm.com Tested-by: Laura Abbott labbott@redhat.com Tested-by: Shanker Donthineni shankerd@codeaurora.org Signed-off-by: Will Deacon will.deacon@arm.com Signed-off-by: Alex Shi alex.shi@linaro.org Signed-off-by: Mark Rutland mark.rutland@arm.com [v4.9 backport] Tested-by: Will Deacon will.deacon@arm.com Tested-by: Greg Hackmann ghackmann@google.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/arm64/include/asm/fixmap.h | 5 +++++ arch/arm64/include/asm/pgtable.h | 1 + arch/arm64/kernel/asm-offsets.c | 6 +++++- arch/arm64/mm/mmu.c | 23 +++++++++++++++++++++++ 4 files changed, 34 insertions(+), 1 deletion(-)
--- a/arch/arm64/include/asm/fixmap.h +++ b/arch/arm64/include/asm/fixmap.h @@ -51,6 +51,11 @@ enum fixed_addresses {
FIX_EARLYCON_MEM_BASE, FIX_TEXT_POKE0, + +#ifdef CONFIG_UNMAP_KERNEL_AT_EL0 + FIX_ENTRY_TRAMP_TEXT, +#define TRAMP_VALIAS (__fix_to_virt(FIX_ENTRY_TRAMP_TEXT)) +#endif /* CONFIG_UNMAP_KERNEL_AT_EL0 */ __end_of_permanent_fixed_addresses,
/* --- a/arch/arm64/include/asm/pgtable.h +++ b/arch/arm64/include/asm/pgtable.h @@ -692,6 +692,7 @@ static inline void pmdp_set_wrprotect(st
extern pgd_t swapper_pg_dir[PTRS_PER_PGD]; extern pgd_t idmap_pg_dir[PTRS_PER_PGD]; +extern pgd_t tramp_pg_dir[PTRS_PER_PGD];
/* * Encode and decode a swap entry: --- a/arch/arm64/kernel/asm-offsets.c +++ b/arch/arm64/kernel/asm-offsets.c @@ -24,6 +24,7 @@ #include <linux/kvm_host.h> #include <linux/suspend.h> #include <asm/cpufeature.h> +#include <asm/fixmap.h> #include <asm/thread_info.h> #include <asm/memory.h> #include <asm/smp_plat.h> @@ -144,11 +145,14 @@ int main(void) DEFINE(ARM_SMCCC_RES_X2_OFFS, offsetof(struct arm_smccc_res, a2)); DEFINE(ARM_SMCCC_QUIRK_ID_OFFS, offsetof(struct arm_smccc_quirk, id)); DEFINE(ARM_SMCCC_QUIRK_STATE_OFFS, offsetof(struct arm_smccc_quirk, state)); - BLANK(); DEFINE(HIBERN_PBE_ORIG, offsetof(struct pbe, orig_address)); DEFINE(HIBERN_PBE_ADDR, offsetof(struct pbe, address)); DEFINE(HIBERN_PBE_NEXT, offsetof(struct pbe, next)); DEFINE(ARM64_FTR_SYSVAL, offsetof(struct arm64_ftr_reg, sys_val)); + BLANK(); +#ifdef CONFIG_UNMAP_KERNEL_AT_EL0 + DEFINE(TRAMP_VALIAS, TRAMP_VALIAS); +#endif return 0; } --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -419,6 +419,29 @@ static void __init map_kernel_segment(pg vm_area_add_early(vma); }
+#ifdef CONFIG_UNMAP_KERNEL_AT_EL0 +static int __init map_entry_trampoline(void) +{ + extern char __entry_tramp_text_start[]; + + pgprot_t prot = rodata_enabled ? PAGE_KERNEL_ROX : PAGE_KERNEL_EXEC; + phys_addr_t pa_start = __pa_symbol(__entry_tramp_text_start); + + /* The trampoline is always mapped and can therefore be global */ + pgprot_val(prot) &= ~PTE_NG; + + /* Map only the text into the trampoline page table */ + memset(tramp_pg_dir, 0, PGD_SIZE); + __create_pgd_mapping(tramp_pg_dir, pa_start, TRAMP_VALIAS, PAGE_SIZE, + prot, pgd_pgtable_alloc, 0); + + /* ...as well as the kernel page table */ + __set_fixmap(FIX_ENTRY_TRAMP_TEXT, pa_start, prot); + return 0; +} +core_initcall(map_entry_trampoline); +#endif + /* * Create fine-grained mappings for the kernel. */
Patches currently in stable-queue which might be from mark.rutland@arm.com 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