diff --git a/Documentation/arm64/silicon-errata.rst b/Documentation/arm64/silicon-errata.rst index 27135b9c07ac..701ec95ebc5e 100644 --- a/Documentation/arm64/silicon-errata.rst +++ b/Documentation/arm64/silicon-errata.rst @@ -129,6 +129,8 @@ stable kernels. +----------------+-----------------+-----------------+-----------------------------+ | ARM | Cortex-X2 | #2224489 | ARM64_ERRATUM_2224489 | +----------------+-----------------+-----------------+-----------------------------+ +| ARM | Cortex-X4 | #3194386 | ARM64_ERRATUM_3194386 | ++----------------+-----------------+-----------------+-----------------------------+ | ARM | Neoverse-N1 | #1188873,1418040| ARM64_ERRATUM_1418040 | +----------------+-----------------+-----------------+-----------------------------+ | ARM | Neoverse-N1 | #1349291 | N/A | @@ -141,6 +143,8 @@ stable kernels. +----------------+-----------------+-----------------+-----------------------------+ | ARM | Neoverse-N2 | #2253138 | ARM64_ERRATUM_2253138 | +----------------+-----------------+-----------------+-----------------------------+ +| ARM | Neoverse-V3 | #3312417 | ARM64_ERRATUM_3312417 | ++----------------+-----------------+-----------------+-----------------------------+ | ARM | MMU-500 | #841119,826419 | N/A | +----------------+-----------------+-----------------+-----------------------------+ | ARM | MMU-600 | #1076982,1209401| N/A | diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 044b98a62f7b..cb9e16823fb2 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -1000,6 +1000,47 @@ config ARM64_ERRATUM_2966298 If unsure, say Y. +config ARM64_WORKAROUND_SPECULATIVE_SSBS + bool + +config ARM64_ERRATUM_3194386 + bool "Cortex-X4: 3194386: workaround for MSR SSBS not self-synchronizing" + select ARM64_WORKAROUND_SPECULATIVE_SSBS + default y + help + This option adds the workaround for ARM Cortex-X4 erratum 3194386. + + On affected cores "MSR SSBS, #0" instructions may not affect + subsequent speculative instructions, which may permit unexepected + speculative store bypassing. + + Work around this problem by placing a speculation barrier after + kernel changes to SSBS. The presence of the SSBS special-purpose + register is hidden from hwcaps and EL0 reads of ID_AA64PFR1_EL1, such + that userspace will use the PR_SPEC_STORE_BYPASS prctl to change + SSBS. + + If unsure, say Y. + +config ARM64_ERRATUM_3312417 + bool "Neoverse-V3: 3312417: workaround for MSR SSBS not self-synchronizing" + select ARM64_WORKAROUND_SPECULATIVE_SSBS + default y + help + This option adds the workaround for ARM Neoverse-V3 erratum 3312417. + + On affected cores "MSR SSBS, #0" instructions may not affect + subsequent speculative instructions, which may permit unexepected + speculative store bypassing. + + Work around this problem by placing a speculation barrier after + kernel changes to SSBS. The presence of the SSBS special-purpose + register is hidden from hwcaps and EL0 reads of ID_AA64PFR1_EL1, such + that userspace will use the PR_SPEC_STORE_BYPASS prctl to change + SSBS. + + If unsure, say Y. + config CAVIUM_ERRATUM_22375 bool "Cavium erratum 22375, 24313" default y diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c index 74584597bfb8..c9d05f753829 100644 --- a/arch/arm64/kernel/cpu_errata.c +++ b/arch/arm64/kernel/cpu_errata.c @@ -435,6 +435,18 @@ static struct midr_range broken_aarch32_aes[] = { }; #endif /* CONFIG_ARM64_WORKAROUND_TRBE_WRITE_OUT_OF_RANGE */ +#ifdef CONFIG_ARM64_WORKAROUND_SPECULATIVE_SSBS +static const struct midr_range erratum_spec_ssbs_list[] = { +#ifdef CONFIG_ARM64_ERRATUM_3194386 + MIDR_ALL_VERSIONS(MIDR_CORTEX_X4), +#endif +#ifdef CONFIG_ARM64_ERRATUM_3312417 + MIDR_ALL_VERSIONS(MIDR_NEOVERSE_V3), +#endif + {} +}; +#endif + const struct arm64_cpu_capabilities arm64_errata[] = { #ifdef CONFIG_ARM64_WORKAROUND_CLEAN_CACHE { @@ -726,6 +738,13 @@ const struct arm64_cpu_capabilities arm64_errata[] = { .cpu_enable = cpu_clear_bf16_from_user_emulation, }, #endif +#ifdef CONFIG_ARM64_WORKAROUND_SPECULATIVE_SSBS + { + .desc = "ARM errata 3194386, 3312417", + .capability = ARM64_WORKAROUND_SPECULATIVE_SSBS, + ERRATA_MIDR_RANGE_LIST(erratum_spec_ssbs_list), + }, +#endif #ifdef CONFIG_ARM64_WORKAROUND_SPECULATIVE_UNPRIV_LOAD { .desc = "ARM erratum 2966298", diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index 770a31c6ed81..840cc48b5147 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -2084,6 +2084,17 @@ static void cpu_enable_mte(struct arm64_cpu_capabilities const *cap) } #endif /* CONFIG_ARM64_MTE */ +static void user_feature_fixup(void) +{ + if (cpus_have_cap(ARM64_WORKAROUND_SPECULATIVE_SSBS)) { + struct arm64_ftr_reg *regp; + + regp = get_arm64_ftr_reg(SYS_ID_AA64PFR1_EL1); + if (regp) + regp->user_mask &= ~ID_AA64PFR1_EL1_SSBS_MASK; + } +} + static void elf_hwcap_fixup(void) { #ifdef CONFIG_ARM64_ERRATUM_1742098 @@ -3284,6 +3295,7 @@ void __init setup_cpu_features(void) u32 cwg; setup_system_capabilities(); + user_feature_fixup(); setup_elf_hwcaps(arm64_elf_hwcaps); if (system_supports_32bit_el0()) { diff --git a/arch/arm64/kernel/proton-pack.c b/arch/arm64/kernel/proton-pack.c index bfce41c2a53b..e476692cea97 100644 --- a/arch/arm64/kernel/proton-pack.c +++ b/arch/arm64/kernel/proton-pack.c @@ -570,6 +570,18 @@ static enum mitigation_state spectre_v4_enable_hw_mitigation(void) /* SCTLR_EL1.DSSBS was initialised to 0 during boot */ set_pstate_ssbs(0); + + /* + * SSBS is self-synchronizing and is intended to affect subsequent + * speculative instructions, but some CPUs can speculate with a stale + * value of SSBS. + * + * Mitigate this with an unconditional speculation barrier, as CPUs + * could mis-speculate branches and bypass a conditional barrier. + */ + if (IS_ENABLED(CONFIG_ARM64_WORKAROUND_SPECULATIVE_SSBS)) + spec_bar(); + return SPECTRE_MITIGATED; } diff --git a/arch/arm64/tools/cpucaps b/arch/arm64/tools/cpucaps index 2dc7ddee5f04..f5c9a4f5f722 100644 --- a/arch/arm64/tools/cpucaps +++ b/arch/arm64/tools/cpucaps @@ -86,4 +86,5 @@ WORKAROUND_NVIDIA_CARMEL_CNP WORKAROUND_QCOM_FALKOR_E1003 WORKAROUND_REPEAT_TLBI WORKAROUND_SPECULATIVE_AT +WORKAROUND_SPECULATIVE_SSBS WORKAROUND_SPECULATIVE_UNPRIV_LOAD