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=-5.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 404C4C32750 for ; Tue, 13 Aug 2019 10:00:07 +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 10E2520663 for ; Tue, 13 Aug 2019 10:00:07 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="tZkRIljO" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 10E2520663 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com 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-Type: Content-Transfer-Encoding:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date:Message-ID:From: References:To:Subject:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=/geTHvmyy8KazeINfnFRTsG42yqCTnH1drmGQjcmBMQ=; b=tZkRIljO9cKDyRnYPnrdPlOjb 6zpTWZczd2dHCXhrU9YesPcaKEytOCGuEzJaSPcUBPF7kaceIREt88QIqHk6EBpUEuazHcTh/N1D8 U3xmWBDxR00HOv9SKDOrjf58CkuugG+JZNO7Cj8I6ezYiWyA8kTr431gzXXb0XvaEypBz6PGAv0A2 GxFtgv1sOp0xj8OKn5nQ4SNY5halidEOQAWgRfCQaIgdZOwUyLiU+8ODMvLGyqDMqVJeSGqDLUotV VeU/I+QHqooJIe0FGsaoXCXQgYVC8yW+ygoxhAcVXkYg3DpvfIry/lvE1101dAxBIaThH0/OZ7QXY 1yFU2oqkw==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1hxTb4-0004Qs-IS; Tue, 13 Aug 2019 10:00:06 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1hxTb0-0003cB-FP for linux-arm-kernel@lists.infradead.org; Tue, 13 Aug 2019 10:00:03 +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 C4342337; Tue, 13 Aug 2019 03:00:00 -0700 (PDT) Received: from dawn-kernel.cambridge.arm.com (unknown [10.1.197.116]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 2E18F3F706; Tue, 13 Aug 2019 03:00:00 -0700 (PDT) Subject: Re: [PATCH 1/2] arm64: Add initial support for E0PD To: broonie@kernel.org, catalin.marinas@arm.com, will@kernel.org References: <20190812125738.17388-1-broonie@kernel.org> <20190812125738.17388-2-broonie@kernel.org> From: Suzuki K Poulose Message-ID: <0e5014d6-83b0-36df-ce6e-f491edffd4f9@arm.com> Date: Tue, 13 Aug 2019 10:59:59 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20190812125738.17388-2-broonie@kernel.org> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190813_030002_567258_B01B6E42 X-CRM114-Status: GOOD ( 17.05 ) 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: linux-arm-kernel@lists.infradead.org Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 12/08/2019 13:57, Mark Brown wrote: > Kernel Page Table Isolation (KPTI) is used to mitigate some speculation > based security issues by ensuring that the kernel is not mapped when > userspace is running but this approach is expensive and is incompatible > with SPE. E0PD, introduced in the ARMv8.5 extensions, provides an > alternative to this which ensures that accesses from userspace to the > kernel's half of the memory map to always fault with constant time, > preventing timing attacks without requiring constant unmapping and > remapping or preventing legitimate accesses. > > This initial patch does not yet integrate with KPTI, this will be dealt > with in followup patches. Ideally we could ensure that by default we > don't use KPTI on CPUs where E0PD is present. > > Signed-off-by: Mark Brown > --- > arch/arm64/Kconfig | 14 +++++++++++++ > arch/arm64/include/asm/cpucaps.h | 3 ++- > arch/arm64/include/asm/pgtable-hwdef.h | 2 ++ > arch/arm64/include/asm/sysreg.h | 1 + > arch/arm64/kernel/cpufeature.c | 27 ++++++++++++++++++++++++++ > 5 files changed, 46 insertions(+), 1 deletion(-) > Reviewed-by: Suzuki K Poulose _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel