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 X-Spam-Level: X-Spam-Status: No, score=-10.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 08794FA372C for ; Fri, 8 Nov 2019 17:01:52 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id CA36D21848 for ; Fri, 8 Nov 2019 17:01:51 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="UNCFXoxj"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=sirena.org.uk header.i=@sirena.org.uk header.b="CdSk8kce" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CA36D21848 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org 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:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version: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=nEIb+xDeUap5O0AsU06ImDNroomokdw+60/DIPj5NU0=; b=UNCFXoxjfXZoDq BBX4lPMVab186tmKAOQ43IVtfLWmbfUbW9m3Kk+t5yKmgeixU7yvG2I13sClCkBiCF1zxblphJp21 6xf8ZLnOjZ3muNmmLKxEblCeQKjfQy2mSQnJkVGmlnFEuWuM7IsMAfmzeJpfWC9PoHDKPk3uhycB2 /nikTg9q53xuBEMLaj0lwG9kNAVSUJMFCXellFNsC88G718y7BYZp1AJLMGXwVp0ILYD7YevmSdaW ZFsmkgGIMZz06UbewAHTdKZO5qQmZ7HnouxVBTyXojrubBiUfahHgxuTS8WEqL6pWfrf7UvHsMhK5 q+SWYVRFB7QrilySuyqA==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1iT7dt-0006P2-QQ; Fri, 08 Nov 2019 17:01:49 +0000 Received: from heliosphere.sirena.org.uk ([172.104.155.198]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1iT7dS-0005yf-Nv for linux-arm-kernel@lists.infradead.org; Fri, 08 Nov 2019 17:01:25 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sirena.org.uk; s=20170815-heliosphere; h=Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From:Sender :Reply-To:Content-Type:Content-ID:Content-Description:Resent-Date:Resent-From :Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help: List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=EtnYr3LmwKuyA2P1mwmaYRggzxzGk7Qd45KJnaTEU0E=; b=CdSk8kcelJI4onOoxuWD3LqkhV u4WpAApEVMyrIwaRRyRVFDXJMhCR+HMIOYONH/gAjH9UnToGvkmBpY/D+5JJfRWqyLHHW8S2XY6Ih dVFI4qpcrddj0bu7Noco0ZHqgR6v3ev/r42dCB+ZInHah1SnWYe0mB4MSm/+7llYPtQ4=; Received: from cpc102320-sgyl38-2-0-cust46.18-2.cable.virginm.net ([82.37.168.47] helo=ypsilon.sirena.org.uk) by heliosphere.sirena.org.uk with esmtpsa (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1iT7dP-0007jZ-6w; Fri, 08 Nov 2019 17:01:19 +0000 Received: by ypsilon.sirena.org.uk (Postfix, from userid 1000) id 8114F2741702; Fri, 8 Nov 2019 17:01:18 +0000 (GMT) From: Mark Brown To: Catalin Marinas , Will Deacon , Suzuki K Poulose Subject: [PATCH v8 3/4] arm64: Don't use KPTI where we have E0PD Date: Fri, 8 Nov 2019 17:01:15 +0000 Message-Id: <20191108170116.32105-4-broonie@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20191108170116.32105-1-broonie@kernel.org> References: <20191108170116.32105-1-broonie@kernel.org> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20191108_090122_835750_0E5182F1 X-CRM114-Status: GOOD ( 13.39 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Brown , linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org Since E0PD is intended to fulfil the same role as KPTI we don't need to use KPTI on CPUs where E0PD is available, we can rely on E0PD instead. Change the check that forces KPTI on when KASLR is enabled to check for E0PD before doing so, CPUs with E0PD are not expected to be affected by meltdown so should not need to enable KPTI for other reasons. Since E0PD is a system capability we will still enable KPTI if any of the CPUs in the system lacks E0PD, this will rewrite any global mappings that were established in systems where some but not all CPUs support E0PD. We may transiently have a mix of global and non-global mappings while booting since we use the local CPU when deciding if KPTI will be required prior to completing CPU enumeration but any global mappings will be converted to non-global ones when KPTI is applied. KPTI can still be forced on from the command line if required. Signed-off-by: Mark Brown --- arch/arm64/include/asm/mmu.h | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/arch/arm64/include/asm/mmu.h b/arch/arm64/include/asm/mmu.h index 55e285fff262..2e2a0ade883c 100644 --- a/arch/arm64/include/asm/mmu.h +++ b/arch/arm64/include/asm/mmu.h @@ -38,10 +38,23 @@ static inline bool arm64_kernel_unmapped_at_el0(void) static inline bool kaslr_requires_kpti(void) { bool tx1_bug; + u64 ftr; if (!IS_ENABLED(CONFIG_RANDOMIZE_BASE)) return false; + /* + * E0PD does a similar job to KPTI so can be used instead + * where available. This will only run before the cpufeature + * code has usefully run and we eventually check on all CPUs so + * we can and must check locally. + */ + if (IS_ENABLED(CONFIG_ARM64_E0PD)) { + ftr = read_sysreg_s(SYS_ID_AA64MMFR2_EL1); + if ((ftr >> ID_AA64MMFR2_E0PD_SHIFT) & 0xf) + return false; + } + /* * Systems affected by Cavium erratum 24756 are incompatible * with KPTI. -- 2.20.1 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel