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[209.132.180.67]) by mx.google.com with ESMTP id t18si11728444pgv.285.2019.02.26.17.06.10; Tue, 26 Feb 2019 17:06:10 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729565AbfB0BGJ (ORCPT + 31 others); Tue, 26 Feb 2019 20:06:09 -0500 Received: from foss.arm.com ([217.140.101.70]:55616 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729520AbfB0BGE (ORCPT ); Tue, 26 Feb 2019 20:06:04 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 45A0616A3; Tue, 26 Feb 2019 17:06:04 -0800 (PST) Received: from beelzebub.austin.arm.com (beelzebub.austin.arm.com [10.118.12.119]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id A59A83F5C1; Tue, 26 Feb 2019 17:06:03 -0800 (PST) From: Jeremy Linton To: linux-arm-kernel@lists.infradead.org Cc: catalin.marinas@arm.com, will.deacon@arm.com, marc.zyngier@arm.com, suzuki.poulose@arm.com, Dave.Martin@arm.com, shankerd@codeaurora.org, julien.thierry@arm.com, mlangsdo@redhat.com, stefan.wahren@i2e.com, Andre.Przywara@arm.com, linux-kernel@vger.kernel.org, Jeremy Linton Subject: [PATCH v5 03/10] arm64: add sysfs vulnerability show for meltdown Date: Tue, 26 Feb 2019 19:05:37 -0600 Message-Id: <20190227010544.597579-4-jeremy.linton@arm.com> X-Mailer: git-send-email 2.17.2 In-Reply-To: <20190227010544.597579-1-jeremy.linton@arm.com> References: <20190227010544.597579-1-jeremy.linton@arm.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Display the mitigation status if active, otherwise assume the cpu is safe unless it doesn't have CSV3 and isn't in our whitelist. Signed-off-by: Jeremy Linton --- arch/arm64/kernel/cpufeature.c | 47 ++++++++++++++++++++++++++-------- 1 file changed, 37 insertions(+), 10 deletions(-) -- 2.20.1 Reviewed-by: Suzuki K Poulose diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index f6d84e2c92fe..d31bd770acba 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -944,7 +944,7 @@ has_useable_cnp(const struct arm64_cpu_capabilities *entry, int scope) return has_cpuid_feature(entry, scope); } -#ifdef CONFIG_UNMAP_KERNEL_AT_EL0 +static bool __meltdown_safe = true; static int __kpti_forced; /* 0: not forced, >0: forced on, <0: forced off */ static bool unmap_kernel_at_el0(const struct arm64_cpu_capabilities *entry, @@ -963,6 +963,16 @@ static bool unmap_kernel_at_el0(const struct arm64_cpu_capabilities *entry, { /* sentinel */ } }; char const *str = "command line option"; + bool meltdown_safe; + + meltdown_safe = is_midr_in_range_list(read_cpuid_id(), kpti_safe_list); + + /* Defer to CPU feature registers */ + if (has_cpuid_feature(entry, scope)) + meltdown_safe = true; + + if (!meltdown_safe) + __meltdown_safe = false; /* * For reasons that aren't entirely clear, enabling KPTI on Cavium @@ -974,6 +984,11 @@ static bool unmap_kernel_at_el0(const struct arm64_cpu_capabilities *entry, __kpti_forced = -1; } + if (!IS_ENABLED(CONFIG_UNMAP_KERNEL_AT_EL0)) { + pr_info_once("kernel page table isolation disabled by CONFIG\n"); + return false; + } + /* Forced? */ if (__kpti_forced) { pr_info_once("kernel page table isolation forced %s by %s\n", @@ -985,14 +1000,10 @@ static bool unmap_kernel_at_el0(const struct arm64_cpu_capabilities *entry, if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) return kaslr_offset() > 0; - /* Don't force KPTI for CPUs that are not vulnerable */ - if (is_midr_in_range_list(read_cpuid_id(), kpti_safe_list)) - return false; - - /* Defer to CPU feature registers */ - return !has_cpuid_feature(entry, scope); + return !meltdown_safe; } +#ifdef CONFIG_UNMAP_KERNEL_AT_EL0 static void kpti_install_ng_mappings(const struct arm64_cpu_capabilities *__unused) { @@ -1022,6 +1033,13 @@ kpti_install_ng_mappings(const struct arm64_cpu_capabilities *__unused) return; } +#else +static void +kpti_install_ng_mappings(const struct arm64_cpu_capabilities *__unused) +{ +} +#endif /* CONFIG_UNMAP_KERNEL_AT_EL0 */ + static int __init parse_kpti(char *str) { @@ -1035,7 +1053,6 @@ static int __init parse_kpti(char *str) return 0; } early_param("kpti", parse_kpti); -#endif /* CONFIG_UNMAP_KERNEL_AT_EL0 */ #ifdef CONFIG_ARM64_HW_AFDBM static inline void __cpu_enable_hw_dbm(void) @@ -1286,7 +1303,6 @@ static const struct arm64_cpu_capabilities arm64_features[] = { .field_pos = ID_AA64PFR0_EL0_SHIFT, .min_field_value = ID_AA64PFR0_EL0_32BIT_64BIT, }, -#ifdef CONFIG_UNMAP_KERNEL_AT_EL0 { .desc = "Kernel page table isolation (KPTI)", .capability = ARM64_UNMAP_KERNEL_AT_EL0, @@ -1302,7 +1318,6 @@ static const struct arm64_cpu_capabilities arm64_features[] = { .matches = unmap_kernel_at_el0, .cpu_enable = kpti_install_ng_mappings, }, -#endif { /* FP/SIMD is not implemented */ .capability = ARM64_HAS_NO_FPSIMD, @@ -2063,3 +2078,15 @@ static int __init enable_mrs_emulation(void) } core_initcall(enable_mrs_emulation); + +ssize_t cpu_show_meltdown(struct device *dev, struct device_attribute *attr, + char *buf) +{ + if (arm64_kernel_unmapped_at_el0()) + return sprintf(buf, "Mitigation: KPTI\n"); + + if (__meltdown_safe) + return sprintf(buf, "Not affected\n"); + + return sprintf(buf, "Vulnerable\n"); +}