From bad52d7979532b20bce7545c18fe7e443b7472f6 Mon Sep 17 00:00:00 2001 From: Mark Rutland Date: Thu, 12 Apr 2018 12:11:21 +0100 Subject: arm64: Implement branch predictor hardening for affected Cortex-A CPUs From: Will Deacon commit aa6acde65e03186b5add8151e1ffe36c3c62639b upstream. Cortex-A57, A72, A73 and A75 are susceptible to branch predictor aliasing and can theoretically 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 affecting other victim contexts. Co-developed-by: Marc Zyngier Signed-off-by: Will Deacon Signed-off-by: Catalin Marinas Signed-off-by: Mark Rutland [v4.9 backport] Tested-by: Greg Hackmann Signed-off-by: Greg Kroah-Hartman --- arch/arm64/kernel/cpu_errata.c | 42 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 42 insertions(+) (limited to 'arch/arm64/kernel/cpu_errata.c') diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c index b9fcbd155df2..5550d18b8180 100644 --- a/arch/arm64/kernel/cpu_errata.c +++ b/arch/arm64/kernel/cpu_errata.c @@ -53,6 +53,8 @@ static int cpu_enable_trap_ctr_access(void *__unused) DEFINE_PER_CPU_READ_MOSTLY(struct bp_hardening_data, bp_hardening_data); #ifdef CONFIG_KVM +extern char __psci_hyp_bp_inval_start[], __psci_hyp_bp_inval_end[]; + static void __copy_hyp_vect_bpi(int slot, const char *hyp_vecs_start, const char *hyp_vecs_end) { @@ -94,6 +96,9 @@ static void __install_bp_hardening_cb(bp_hardening_cb_t fn, spin_unlock(&bp_lock); } #else +#define __psci_hyp_bp_inval_start NULL +#define __psci_hyp_bp_inval_end NULL + static void __install_bp_hardening_cb(bp_hardening_cb_t fn, const char *hyp_vecs_start, const char *hyp_vecs_end) @@ -118,6 +123,21 @@ static void install_bp_hardening_cb(const struct arm64_cpu_capabilities *entry, __install_bp_hardening_cb(fn, hyp_vecs_start, hyp_vecs_end); } + +#include + +static int enable_psci_bp_hardening(void *data) +{ + const struct arm64_cpu_capabilities *entry = data; + + if (psci_ops.get_version) + install_bp_hardening_cb(entry, + (bp_hardening_cb_t)psci_ops.get_version, + __psci_hyp_bp_inval_start, + __psci_hyp_bp_inval_end); + + return 0; +} #endif /* CONFIG_HARDEN_BRANCH_PREDICTOR */ #define MIDR_RANGE(model, min, max) \ @@ -211,6 +231,28 @@ const struct arm64_cpu_capabilities arm64_errata[] = { .def_scope = SCOPE_LOCAL_CPU, .enable = cpu_enable_trap_ctr_access, }, +#ifdef CONFIG_HARDEN_BRANCH_PREDICTOR + { + .capability = ARM64_HARDEN_BRANCH_PREDICTOR, + MIDR_ALL_VERSIONS(MIDR_CORTEX_A57), + .enable = enable_psci_bp_hardening, + }, + { + .capability = ARM64_HARDEN_BRANCH_PREDICTOR, + MIDR_ALL_VERSIONS(MIDR_CORTEX_A72), + .enable = enable_psci_bp_hardening, + }, + { + .capability = ARM64_HARDEN_BRANCH_PREDICTOR, + MIDR_ALL_VERSIONS(MIDR_CORTEX_A73), + .enable = enable_psci_bp_hardening, + }, + { + .capability = ARM64_HARDEN_BRANCH_PREDICTOR, + MIDR_ALL_VERSIONS(MIDR_CORTEX_A75), + .enable = enable_psci_bp_hardening, + }, +#endif { } }; -- cgit v1.2.3