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author | Marc Zyngier <marc.zyngier@arm.com> | 2018-05-29 13:11:08 +0100 |
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committer | Catalin Marinas <catalin.marinas@arm.com> | 2018-05-31 17:34:38 +0100 |
commit | a725e3dda1813ed306734823ac4c65ca04e38500 (patch) | |
tree | 921b44e586ea91ce97beb07ce6d59979d8fd9bc2 /arch/arm64/kernel/cpu_errata.c | |
parent | 5cf9ce6e5ea50f805c6188c04ed0daaec7b6887d (diff) | |
download | linux-stable-a725e3dda1813ed306734823ac4c65ca04e38500.tar.gz linux-stable-a725e3dda1813ed306734823ac4c65ca04e38500.tar.bz2 linux-stable-a725e3dda1813ed306734823ac4c65ca04e38500.zip |
arm64: Add ARCH_WORKAROUND_2 probing
As for Spectre variant-2, we rely on SMCCC 1.1 to provide the
discovery mechanism for detecting the SSBD mitigation.
A new capability is also allocated for that purpose, and a
config option.
Reviewed-by: Julien Grall <julien.grall@arm.com>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch/arm64/kernel/cpu_errata.c')
-rw-r--r-- | arch/arm64/kernel/cpu_errata.c | 69 |
1 files changed, 69 insertions, 0 deletions
diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c index cd91ca0250f1..7e8f12d85d99 100644 --- a/arch/arm64/kernel/cpu_errata.c +++ b/arch/arm64/kernel/cpu_errata.c @@ -256,6 +256,67 @@ void __init arm64_update_smccc_conduit(struct alt_instr *alt, *updptr = cpu_to_le32(insn); } + +static void arm64_set_ssbd_mitigation(bool state) +{ + switch (psci_ops.conduit) { + case PSCI_CONDUIT_HVC: + arm_smccc_1_1_hvc(ARM_SMCCC_ARCH_WORKAROUND_2, state, NULL); + break; + + case PSCI_CONDUIT_SMC: + arm_smccc_1_1_smc(ARM_SMCCC_ARCH_WORKAROUND_2, state, NULL); + break; + + default: + WARN_ON_ONCE(1); + break; + } +} + +static bool has_ssbd_mitigation(const struct arm64_cpu_capabilities *entry, + int scope) +{ + struct arm_smccc_res res; + bool supported = true; + + WARN_ON(scope != SCOPE_LOCAL_CPU || preemptible()); + + if (psci_ops.smccc_version == SMCCC_VERSION_1_0) + return false; + + /* + * The probe function return value is either negative + * (unsupported or mitigated), positive (unaffected), or zero + * (requires mitigation). We only need to do anything in the + * last case. + */ + switch (psci_ops.conduit) { + case PSCI_CONDUIT_HVC: + arm_smccc_1_1_hvc(ARM_SMCCC_ARCH_FEATURES_FUNC_ID, + ARM_SMCCC_ARCH_WORKAROUND_2, &res); + if ((int)res.a0 != 0) + supported = false; + break; + + case PSCI_CONDUIT_SMC: + arm_smccc_1_1_smc(ARM_SMCCC_ARCH_FEATURES_FUNC_ID, + ARM_SMCCC_ARCH_WORKAROUND_2, &res); + if ((int)res.a0 != 0) + supported = false; + break; + + default: + supported = false; + } + + if (supported) { + __this_cpu_write(arm64_ssbd_callback_required, 1); + arm64_set_ssbd_mitigation(true); + } + + return supported; +} #endif /* CONFIG_ARM64_SSBD */ #define CAP_MIDR_RANGE(model, v_min, r_min, v_max, r_max) \ @@ -513,6 +574,14 @@ const struct arm64_cpu_capabilities arm64_errata[] = { ERRATA_MIDR_RANGE_LIST(arm64_harden_el2_vectors), }, #endif +#ifdef CONFIG_ARM64_SSBD + { + .desc = "Speculative Store Bypass Disable", + .capability = ARM64_SSBD, + .type = ARM64_CPUCAP_LOCAL_CPU_ERRATUM, + .matches = has_ssbd_mitigation, + }, +#endif { } }; |