From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 6A441C433EF for ; Tue, 15 Mar 2022 18:32:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=oiaOYc7xIVdIKq00QjVESOxpLstTKf/M5mR6mxNaSE4=; b=MXuXtVKf52YRW+ 9PSDlSLDShyJmUsH1FGgHjKGI0kDfF8w+vkTL/XJ11s9nqmmF08/nLicpzOUJZYi/lpw30euDX/7s 434k/jYvhRqyuVzZ5q4nP2gNNIVX8wm665YOgAwYZ536Bzl2cZRGfzCzK2WHdG+HppdXDiazZvDuD 7zGh47sJNEJwGTN2RlAiOU1EXQ7oDWVxSKKb2iQsMkqaJoMoshzH2Eosx8zOuXJX5htGK2MoLuhn5 7na7lfZ2cO4q0TYbZay77OuRNCpfVGdaldYeu+n1Bqm9UAqRQDqNnGsvQ3qGWNgnD1EYcumCHwmVz Q4b141WkbJ7KNQdkjypA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nUBxG-00AEyB-R6; Tue, 15 Mar 2022 18:31:36 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nUBqi-00ABeC-RA for linux-arm-kernel@lists.infradead.org; Tue, 15 Mar 2022 18:24:50 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 8D9871474; Tue, 15 Mar 2022 11:24:48 -0700 (PDT) Received: from eglon.cambridge.arm.com (eglon.cambridge.arm.com [10.1.196.218]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id E209F3F73D; Tue, 15 Mar 2022 11:24:47 -0700 (PDT) From: James Morse To: stable@vger.kernel.org Cc: catalin.marinas@arm.com, linux-arm-kernel@lists.infradead.org, james.morse@arm.com Subject: [stable:PATCH v5.4.184 18/22] arm64: proton-pack: Report Spectre-BHB vulnerabilities as part of Spectre-v2 Date: Tue, 15 Mar 2022 18:24:11 +0000 Message-Id: <20220315182415.3900464-19-james.morse@arm.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20220315182415.3900464-1-james.morse@arm.com> References: <20220315182415.3900464-1-james.morse@arm.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220315_112449_009152_18C64505 X-CRM114-Status: GOOD ( 11.42 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org commit dee435be76f4117410bbd90573a881fd33488f37 upstream. Speculation attacks against some high-performance processors can make use of branch history to influence future speculation as part of a spectre-v2 attack. This is not mitigated by CSV2, meaning CPUs that previously reported 'Not affected' are now moderately mitigated by CSV2. Update the value in /sys/devices/system/cpu/vulnerabilities/spectre_v2 to also show the state of the BHB mitigation. Reviewed-by: Catalin Marinas [ code move to cpu_errata.c for backport ] Signed-off-by: James Morse --- arch/arm64/include/asm/cpufeature.h | 9 +++++++ arch/arm64/kernel/cpu_errata.c | 41 ++++++++++++++++++++++++++--- 2 files changed, 46 insertions(+), 4 deletions(-) diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h index ccae05da98a7..a798443ed76f 100644 --- a/arch/arm64/include/asm/cpufeature.h +++ b/arch/arm64/include/asm/cpufeature.h @@ -639,6 +639,15 @@ static inline int arm64_get_ssbd_state(void) void arm64_set_ssbd_mitigation(bool state); +/* Watch out, ordering is important here. */ +enum mitigation_state { + SPECTRE_UNAFFECTED, + SPECTRE_MITIGATED, + SPECTRE_VULNERABLE, +}; + +enum mitigation_state arm64_get_spectre_bhb_state(void); + extern int do_emulate_mrs(struct pt_regs *regs, u32 sys_reg, u32 rt); static inline u32 id_aa64mmfr0_parange_to_phys_shift(int parange) diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c index 1e16c4e00e77..182305000de3 100644 --- a/arch/arm64/kernel/cpu_errata.c +++ b/arch/arm64/kernel/cpu_errata.c @@ -989,15 +989,41 @@ ssize_t cpu_show_spectre_v1(struct device *dev, struct device_attribute *attr, return sprintf(buf, "Mitigation: __user pointer sanitization\n"); } +static const char *get_bhb_affected_string(enum mitigation_state bhb_state) +{ + switch (bhb_state) { + case SPECTRE_UNAFFECTED: + return ""; + default: + case SPECTRE_VULNERABLE: + return ", but not BHB"; + case SPECTRE_MITIGATED: + return ", BHB"; + } +} + ssize_t cpu_show_spectre_v2(struct device *dev, struct device_attribute *attr, char *buf) { + enum mitigation_state bhb_state = arm64_get_spectre_bhb_state(); + const char *bhb_str = get_bhb_affected_string(bhb_state); + const char *v2_str = "Branch predictor hardening"; + switch (get_spectre_v2_workaround_state()) { case ARM64_BP_HARDEN_NOT_REQUIRED: - return sprintf(buf, "Not affected\n"); - case ARM64_BP_HARDEN_WA_NEEDED: - return sprintf(buf, "Mitigation: Branch predictor hardening\n"); - case ARM64_BP_HARDEN_UNKNOWN: + if (bhb_state == SPECTRE_UNAFFECTED) + return sprintf(buf, "Not affected\n"); + + /* + * Platforms affected by Spectre-BHB can't report + * "Not affected" for Spectre-v2. + */ + v2_str = "CSV2"; + fallthrough; + case ARM64_BP_HARDEN_WA_NEEDED: + return sprintf(buf, "Mitigation: %s%s\n", v2_str, bhb_str); + case ARM64_BP_HARDEN_UNKNOWN: + fallthrough; default: return sprintf(buf, "Vulnerable\n"); } @@ -1019,3 +1045,10 @@ ssize_t cpu_show_spec_store_bypass(struct device *dev, return sprintf(buf, "Vulnerable\n"); } + +static enum mitigation_state spectre_bhb_state; + +enum mitigation_state arm64_get_spectre_bhb_state(void) +{ + return spectre_bhb_state; +} -- 2.30.2 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel