From patchwork Wed Apr 10 23:12:30 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jeremy Linton X-Patchwork-Id: 162053 Delivered-To: patch@linaro.org Received: by 2002:a02:c6d8:0:0:0:0:0 with SMTP id r24csp6763564jan; Wed, 10 Apr 2019 16:13:44 -0700 (PDT) X-Google-Smtp-Source: APXvYqyBiQxKtjr7nD4lawZ9Zf8ctH/6nPro1wV4YxVwJf1RcgLiFOhdWYeTGBi31CoDrXANwhjd X-Received: by 2002:a17:902:1621:: with SMTP id g30mr15404954plg.168.1554938024263; Wed, 10 Apr 2019 16:13:44 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1554938024; cv=none; d=google.com; s=arc-20160816; b=SA+UKPdDKtir+O/ZpoqEK4SPYUgtg2T3tHzlgp7kU4+uj7l7b2pi4/vL0BIeUt039d EnN//tneN3UXX4aUz8xL/L9iqiz3P1hkzMja5SpJZpEkTuUWgiYJS7TsmeCNWFCZ7m3V ZzwiCmM29db3Cl/6m8ewMvfHrvYQaZbQ4gsS3L7H0+HAjy5sCgfRilTqtadJkALy9gma qI42c0+ZL1JjrAq+1Zfz2vDPoSaVH/tJUKRCU7k9Uq5rhQZBTOQXSRz2MMxrmY96xY7J sfGbVeS7zTKpNan9VK/XZ8W1AeYGJRAIExk6ujkJxapBTYvjRMD1pVlCZPTPqbmYPydb Qhdg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:content-transfer-encoding:mime-version :references:in-reply-to:message-id:date:subject:cc:to:from; bh=a6m7OOqx8DQTBLA6Hx7GSOf6BgSt5i17jWKolol5ZCg=; b=oBD7OisoSRvg00Um8WUBu6h1y5i3uTAHgmIA7SoGbPFAP1kwaI8xnCqbLy/nSCH7b+ QtxJWXtnO+/94JdBLeyBP1E65PV5po1QJwQo+9JhM3CSow/DkOgiy8BZgX2QPF2+hjzn 1xPmM23TqQ1kVYjUVzk74/i7J5O0bSE/UxAnS6IPCF9loqYgNrYG+11lbWHHiNeSoyNn 000E7GJKIO50d2QJFdjeYMgKOzCUvij5YD3m+f3hGPpyYk7cfW/MCVxmZ1PWjkqi57P+ W5yzFViyP4a9xtamF4mbgSYxz3ZaoTFixoZtgRkC0OC6uDKqlk48Ov/WzcqsecRx5Wg6 FZmQ== ARC-Authentication-Results: i=1; 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 Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id w10si30155979plz.37.2019.04.10.16.13.43; Wed, 10 Apr 2019 16:13:44 -0700 (PDT) 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 S1727020AbfDJXNi (ORCPT + 31 others); Wed, 10 Apr 2019 19:13:38 -0400 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:33010 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726801AbfDJXM4 (ORCPT ); Wed, 10 Apr 2019 19:12:56 -0400 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 358DA15BF; Wed, 10 Apr 2019 16:12:56 -0700 (PDT) Received: from mammon-tx2.austin.arm.com (mammon-tx2.austin.arm.com [10.118.29.246]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 8C10D3F557; Wed, 10 Apr 2019 16:12:55 -0700 (PDT) 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@i2se.com, Andre.Przywara@arm.com, linux-kernel@vger.kernel.org, Jeremy Linton , Andre Przywara Subject: [v7 03/10] arm64: add sysfs vulnerability show for meltdown Date: Wed, 10 Apr 2019 18:12:30 -0500 Message-Id: <20190410231237.52506-4-jeremy.linton@arm.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190410231237.52506-1-jeremy.linton@arm.com> References: <20190410231237.52506-1-jeremy.linton@arm.com> MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Display the system vulnerability status. This means that while its possible to have the mitigation enabled, the sysfs entry won't indicate that status. This is because the core ABI doesn't express the concept of mitigation when the system isn't vulnerable. Signed-off-by: Jeremy Linton Reviewed-by: Suzuki K Poulose Reviewed-by: Andre Przywara Reviewed-by: Catalin Marinas Tested-by: Stefan Wahren --- arch/arm64/kernel/cpufeature.c | 58 ++++++++++++++++++++++++++-------- 1 file changed, 44 insertions(+), 14 deletions(-) -- 2.20.1 diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index 4061de10cea6..6b7e1556460a 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -947,7 +947,7 @@ 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, @@ -967,6 +967,16 @@ 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 @@ -978,6 +988,19 @@ static bool unmap_kernel_at_el0(const struct arm64_cpu_capabilities *entry, __kpti_forced = -1; } + /* Useful for KASLR robustness */ + if (IS_ENABLED(CONFIG_RANDOMIZE_BASE) && kaslr_offset() > 0) { + if (!__kpti_forced) { + str = "KASLR"; + __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", @@ -985,18 +1008,10 @@ static bool unmap_kernel_at_el0(const struct arm64_cpu_capabilities *entry, return __kpti_forced > 0; } - /* Useful for KASLR robustness */ - 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) { @@ -1026,6 +1041,12 @@ 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) { @@ -1039,7 +1060,6 @@ 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) @@ -1306,7 +1326,6 @@ 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, @@ -1322,7 +1341,6 @@ 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, @@ -2101,3 +2119,15 @@ 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 (__meltdown_safe) + return sprintf(buf, "Not affected\n"); + + if (arm64_kernel_unmapped_at_el0()) + return sprintf(buf, "Mitigation: KPTI\n"); + + return sprintf(buf, "Vulnerable\n"); +}