[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-changelog] [xen stable-4.10] xen/arm64: Implement branch predictor hardening for affected Cortex-A CPUs
commit 928112900e5b4a92ccebb2eea11665fd76aa0f0d Author: Julien Grall <julien.grall@xxxxxxxxxx> AuthorDate: Tue Jan 16 14:23:37 2018 +0000 Commit: Stefano Stabellini <sstabellini@xxxxxxxxxx> CommitDate: Wed Jan 24 13:12:30 2018 -0800 xen/arm64: Implement branch predictor hardening for affected Cortex-A CPUs Cortex-A57, A72, A73 and A75 are susceptible to branch predictor aliasing and can theoritically be attacked by malicious code. This patch implements a PSCI-based mitigation for these CPUs when available. The call into firmware will invalidate the branch predictor state, preventing any malicious entries from affection other victim contexts. Ported from Linux git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git branch kpti. Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx> Signed-off-by: Will Deacon <will.deacon@xxxxxxx> This is part of XSA-254. Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx> Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx> (cherry picked from commit e730f8e41e8537f1db9770b9464f9523c28857b9) --- xen/arch/arm/arm64/bpi.S | 25 ++++++++++++++++++++++++ xen/arch/arm/cpuerrata.c | 49 ++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 74 insertions(+) diff --git a/xen/arch/arm/arm64/bpi.S b/xen/arch/arm/arm64/bpi.S index 6cc2f17..4b7f1dc 100644 --- a/xen/arch/arm/arm64/bpi.S +++ b/xen/arch/arm/arm64/bpi.S @@ -56,6 +56,31 @@ ENTRY(__bp_harden_hyp_vecs_start) .endr ENTRY(__bp_harden_hyp_vecs_end) +ENTRY(__psci_hyp_bp_inval_start) + sub sp, sp, #(8 * 18) + stp x16, x17, [sp, #(16 * 0)] + stp x14, x15, [sp, #(16 * 1)] + stp x12, x13, [sp, #(16 * 2)] + stp x10, x11, [sp, #(16 * 3)] + stp x8, x9, [sp, #(16 * 4)] + stp x6, x7, [sp, #(16 * 5)] + stp x4, x5, [sp, #(16 * 6)] + stp x2, x3, [sp, #(16 * 7)] + stp x0, x1, [sp, #(16 * 8)] + mov x0, #0x84000000 + smc #0 + ldp x16, x17, [sp, #(16 * 0)] + ldp x14, x15, [sp, #(16 * 1)] + ldp x12, x13, [sp, #(16 * 2)] + ldp x10, x11, [sp, #(16 * 3)] + ldp x8, x9, [sp, #(16 * 4)] + ldp x6, x7, [sp, #(16 * 5)] + ldp x4, x5, [sp, #(16 * 6)] + ldp x2, x3, [sp, #(16 * 7)] + ldp x0, x1, [sp, #(16 * 8)] + add sp, sp, #(8 * 18) +ENTRY(__psci_hyp_bp_inval_end) + /* * Local variables: * mode: ASM diff --git a/xen/arch/arm/cpuerrata.c b/xen/arch/arm/cpuerrata.c index 76d98e7..f1ea7f3 100644 --- a/xen/arch/arm/cpuerrata.c +++ b/xen/arch/arm/cpuerrata.c @@ -4,8 +4,10 @@ #include <xen/smp.h> #include <xen/spinlock.h> #include <xen/vmap.h> +#include <xen/warning.h> #include <asm/cpufeature.h> #include <asm/cpuerrata.h> +#include <asm/psci.h> /* Override macros from asm/page.h to make them work with mfn_t */ #undef virt_to_mfn @@ -141,6 +143,31 @@ install_bp_hardening_vec(const struct arm_cpu_capabilities *entry, return ret; } +extern char __psci_hyp_bp_inval_start[], __psci_hyp_bp_inval_end[]; + +static int enable_psci_bp_hardening(void *data) +{ + bool ret = true; + static bool warned = false; + + /* + * The mitigation is using PSCI version function to invalidate the + * branch predictor. This function is only available with PSCI 0.2 + * and later. + */ + if ( psci_ver >= PSCI_VERSION(0, 2) ) + ret = install_bp_hardening_vec(data, __psci_hyp_bp_inval_start, + __psci_hyp_bp_inval_end); + else if ( !warned ) + { + ASSERT(system_state < SYS_STATE_active); + warning_add("PSCI 0.2 or later is required for the branch predictor hardening.\n"); + warned = true; + } + + return !ret; +} + #endif /* CONFIG_ARM64_HARDEN_BRANCH_PREDICTOR */ #define MIDR_RANGE(model, min, max) \ @@ -205,6 +232,28 @@ static const struct arm_cpu_capabilities arm_errata[] = { (1 << MIDR_VARIANT_SHIFT) | 2), }, #endif +#ifdef CONFIG_ARM64_HARDEN_BRANCH_PREDICTOR + { + .capability = ARM_HARDEN_BRANCH_PREDICTOR, + MIDR_ALL_VERSIONS(MIDR_CORTEX_A57), + .enable = enable_psci_bp_hardening, + }, + { + .capability = ARM_HARDEN_BRANCH_PREDICTOR, + MIDR_ALL_VERSIONS(MIDR_CORTEX_A72), + .enable = enable_psci_bp_hardening, + }, + { + .capability = ARM_HARDEN_BRANCH_PREDICTOR, + MIDR_ALL_VERSIONS(MIDR_CORTEX_A73), + .enable = enable_psci_bp_hardening, + }, + { + .capability = ARM_HARDEN_BRANCH_PREDICTOR, + MIDR_ALL_VERSIONS(MIDR_CORTEX_A75), + .enable = enable_psci_bp_hardening, + }, +#endif {}, }; -- generated by git-patchbot for /home/xen/git/xen.git#stable-4.10 _______________________________________________ Xen-changelog mailing list Xen-changelog@xxxxxxxxxxxxxxxxxxxx https://lists.xenproject.org/xen-changelog
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