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=-2.5 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, USER_AGENT_MUTT 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 BB3EBC43381 for ; Fri, 1 Mar 2019 11:45:30 +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 831652083E for ; Fri, 1 Mar 2019 11:45:30 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="JGTCJ4AT" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 831652083E 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-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=eVLEOiMbmR1/oCaeVKitvft4lMnGj11RcJ+dqAyV+14=; b=JGTCJ4ATb0Jwgc VxySF09Fa4cfy5BCNhvOXJxwd74eECyJmMFr5HgB5vIbcBovUUHOnHQiciPIFT6UbiWTAJfvj2x17 RTHIxY/8QmHCew/DZAUvsQJaj5vwhzv8DaKRtLQeXee2yryqfnnJC88/QmOqZuNYucLCqCvhh+IlS ZE1T/8MFo0MIoiQOu4ucCQBvSmdbdzNtLdY9pG4ff8hblWGpmeQB8PJUMzVQ/nBGEs/zkiLaCq6TX bl2NsM29FkZmgJCqX3OyynCKNGyqkLx/5pab6QrfH0zqxqCd1w6EoHTmvfcm09jIGxKyd7TUCIjv4 KEZtKdJo6DPREg7C1yUw==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1gzgbW-0000l9-4E; Fri, 01 Mar 2019 11:45:26 +0000 Received: from foss.arm.com ([217.140.101.70]) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1gzgbT-0000km-BG for linux-arm-kernel@lists.infradead.org; Fri, 01 Mar 2019 11:45:24 +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 08374EBD; Fri, 1 Mar 2019 03:45:22 -0800 (PST) Received: from fuggles.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.72.51.249]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 7EE553F5C1; Fri, 1 Mar 2019 03:45:20 -0800 (PST) Date: Fri, 1 Mar 2019 11:45:15 +0000 From: Will Deacon To: Ard Biesheuvel Subject: Re: [PATCH] arm64: kpti: Update arm64_kernel_use_ng_mappings() when forced on Message-ID: <20190301114515.GA22795@fuggles.cambridge.arm.com> References: <20190115184917.248995-1-james.morse@arm.com> <21310b0b-8a75-1adf-a844-b2f3f520fa2d@huawei.com> <835dc899-578c-d914-4ed3-fa8b3b391ae6@huawei.com> <20190301113512.GA22488@fuggles.cambridge.arm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.11.1+86 (6f28e57d73f2) () X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190301_034523_394302_A935E159 X-CRM114-Status: GOOD ( 20.39 ) 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: Catalin Marinas , John Garry , Linuxarm , James Morse , huangdaode , "Guohanjun \(Hanjun Guo\)" , linux-arm-kernel 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 On Fri, Mar 01, 2019 at 12:43:01PM +0100, Ard Biesheuvel wrote: > On Fri, 1 Mar 2019 at 12:35, Will Deacon wrote: > > > > On Fri, Mar 01, 2019 at 11:18:21AM +0000, John Garry wrote: > > > On 16/01/2019 09:38, John Garry wrote: > > > > On 15/01/2019 18:49, James Morse wrote: > > > > > Since commit b89d82ef01b3 ("arm64: kpti: Avoid rewriting early page > > > > > > > > About b89d82ef01b3, I got an *unconfirmed* (emphasis on this, I don't > > > > want to cry wolf) report yesterday that the symptom I saw (boot delay) > > > > has been seen on 5.0-rc2 on our D06 board. I could not see it. > > > > > > > > Please note that this would be same board which we saw this on: > > > > https://lkml.org/lkml/2018/6/20/589 > > > > > > > > I only witnessed the issue on the predecessor A72-based D05 board. > > > > > > > > The reporter is very busy, but we'll keep tabs on it. > > > > > > > > > > FYI, this just came in this morning: > > > > This isn't completely surprising, because the kernel doesn't know about > > the CPU in D06: > > > > > [ 0.000000] Booting Linux on physical CPU 0x0000010000 [0x480fd010] > > > > [...] > > > > > [ 0.000000] CPU features: detected: Kernel page table isolation (KPTI) > > > > If the CPU is not affected by meltdown, you can add the MIDR above to the > > kpti_safe_list[] table. If it *is* affected by meltdown, then I'm afraid > > that you're stuck with the delay at boot for !KASLR kernels (which is an > > awful lot better than getting pwned by userspace :) > > > > I think D06 is 8.2, so I would've hoped that you'd implemented > > AA64PFR0_EL1.CSV3, which would make this MIDR-based whitelisting > > unnecessary. > > > > Note that this is also still tied to the new rodata handling. The new > default is rodata=full, and reverting back to rodata=on (which used to > be the default in prior releases) or rodata=off (not recommended) > should get around this as well. Or, somewhat perversely, enabling CONFIG_RANDOMIZE_BASE and passing a valid kaslr seed. Performance /and/ security! Will _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel