From patchwork Fri Jan 5 13:12:33 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Will Deacon X-Patchwork-Id: 10146443 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 7B70860244 for ; Fri, 5 Jan 2018 13:14:35 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 68901288B3 for ; Fri, 5 Jan 2018 13:14:35 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 5BE09288B5; Fri, 5 Jan 2018 13:14:35 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.2 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from bombadil.infradead.org (bombadil.infradead.org [65.50.211.133]) (using TLSv1.2 with cipher AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id C4723288B3 for ; Fri, 5 Jan 2018 13:14:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:MIME-Version:Cc:List-Subscribe: List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id:References: In-Reply-To:Message-Id:Date:Subject:To:From:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Owner; bh=HRQuaae0Tsm/iRljN2apJcisyk5+LjODLie3/kWAfdU=; b=ZifK3EnbTA88+s2OOCZbqM7n36 OXzdvSj//55HOSW+lPQaJRkB+7YWWsrf6dzyeAuVvdjSrCavdqNlzXCMCSaAAWKjjg24q3VL9jIfu nIgRdC9vFsyeFkyx8N9ivKsS8U0ev575hakL8m5yhNUD5fvAn+nCJrR4QiB+8fgoawpBc5FFwORpT x8hxAV08ybR40eN6NGCSiiNp2/DXITcyb3tKrrXBEB4eAWUjurdOGBbn/ErTawQ3801x+s5D27A/R A5MZ8UFfngTP1V2AEZnBtWB1y1l8h+KvUHZl88aB9uqbaDvzd5EUZgAwE0KZAyXjjnWHWuAMKCv/o v6OJCp/g==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.89 #1 (Red Hat Linux)) id 1eXRpP-0005Hw-8j; Fri, 05 Jan 2018 13:14:31 +0000 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70] helo=foss.arm.com) by bombadil.infradead.org with esmtp (Exim 4.89 #1 (Red Hat Linux)) id 1eXRnp-0004Iv-5C for linux-arm-kernel@lists.infradead.org; Fri, 05 Jan 2018 13:12:57 +0000 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 D140615BF; Fri, 5 Jan 2018 05:12:42 -0800 (PST) Received: from edgewater-inn.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.72.51.249]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 9C88C3F7BD; Fri, 5 Jan 2018 05:12:42 -0800 (PST) Received: by edgewater-inn.cambridge.arm.com (Postfix, from userid 1000) id 182801AE17F0; Fri, 5 Jan 2018 13:12:43 +0000 (GMT) From: Will Deacon To: linux-arm-kernel@lists.infradead.org Subject: [PATCH v2 03/11] arm64: Take into account ID_AA64PFR0_EL1.CSV3 Date: Fri, 5 Jan 2018 13:12:33 +0000 Message-Id: <1515157961-20963-4-git-send-email-will.deacon@arm.com> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1515157961-20963-1-git-send-email-will.deacon@arm.com> References: <1515157961-20963-1-git-send-email-will.deacon@arm.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20180105_051253_370106_3266B172 X-CRM114-Status: GOOD ( 13.66 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: lorenzo.pieralisi@arm.com, ard.biesheuvel@linaro.org, marc.zyngier@arm.com, catalin.marinas@arm.com, Will Deacon , linux-kernel@vger.kernel.org, labbott@redhat.com, christoffer.dall@linaro.org MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP For non-KASLR kernels where the KPTI behaviour has not been overridden on the command line we can use ID_AA64PFR0_EL1.CSV3 to determine whether or not we should unmap the kernel whilst running at EL0. Reviewed-by: Suzuki K Poulose Signed-off-by: Will Deacon --- arch/arm64/include/asm/sysreg.h | 1 + arch/arm64/kernel/cpufeature.c | 8 +++++++- 2 files changed, 8 insertions(+), 1 deletion(-) diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h index 08cc88574659..ae519bbd3f9e 100644 --- a/arch/arm64/include/asm/sysreg.h +++ b/arch/arm64/include/asm/sysreg.h @@ -437,6 +437,7 @@ #define ID_AA64ISAR1_DPB_SHIFT 0 /* id_aa64pfr0 */ +#define ID_AA64PFR0_CSV3_SHIFT 60 #define ID_AA64PFR0_SVE_SHIFT 32 #define ID_AA64PFR0_GIC_SHIFT 24 #define ID_AA64PFR0_ASIMD_SHIFT 20 diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index 9f0545dfe497..d723fc071f39 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -145,6 +145,7 @@ static const struct arm64_ftr_bits ftr_id_aa64isar1[] = { }; static const struct arm64_ftr_bits ftr_id_aa64pfr0[] = { + ARM64_FTR_BITS(FTR_HIDDEN, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64PFR0_CSV3_SHIFT, 4, 0), ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR0_SVE_SHIFT, 4, 0), ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR0_GIC_SHIFT, 4, 0), S_ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR0_ASIMD_SHIFT, 4, ID_AA64PFR0_ASIMD_NI), @@ -851,6 +852,8 @@ 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, int __unused) { + u64 pfr0 = read_sanitised_ftr_reg(SYS_ID_AA64PFR0_EL1); + /* Forced on command line? */ if (__kpti_forced) { pr_info_once("kernel page table isolation forced %s by command line option\n", @@ -862,7 +865,9 @@ static bool unmap_kernel_at_el0(const struct arm64_cpu_capabilities *entry, if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) return true; - return false; + /* Defer to CPU feature registers */ + return !cpuid_feature_extract_unsigned_field(pfr0, + ID_AA64PFR0_CSV3_SHIFT); } static int __init parse_kpti(char *str) @@ -967,6 +972,7 @@ static const struct arm64_cpu_capabilities arm64_features[] = { }, #ifdef CONFIG_UNMAP_KERNEL_AT_EL0 { + .desc = "Kernel page table isolation (KPTI)", .capability = ARM64_UNMAP_KERNEL_AT_EL0, .def_scope = SCOPE_SYSTEM, .matches = unmap_kernel_at_el0,