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=-8.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, NICE_REPLY_A,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 6E445C433DF for ; Fri, 16 Oct 2020 10:29:14 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (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 DEFDC207F7 for ; Fri, 16 Oct 2020 10:29:13 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="MY/snDzN" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DEFDC207F7 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+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=merlin.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: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=bztibQpRCONorwAbtiakj+RyPJPT4UPRPceMI5wHETU=; b=MY/snDzNCqMWkxVo8oMiNbu1h 6retb/a8p7PDiR0i+iTMIP0wFZhwYFHp1JFvO3oYAbCiBFjWAtpAgP35tOE/e+BatV4pJkxM0do4P Fwc6sYvGIYmxIFDoLWF+HlJ8G9vOcWH8aTTyZZILfkZqop0ZGJoQXYntT49NCljbMK2fhumhUmE7r ANKNKa81m/46V9jhn29ZaNJ8A4iT21hxo3WDZBb1kDDAEML+giYsRoqPOKhn8pYTvjaCPay5h4nED mV41FpVDVjTM6pA7uQMtX1X77WZbqvqrzXoKoCPr3oJGbZP9bh5zgdnexkF/rZdXEh7A7l05v/obZ BFDEXgmuQ==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kTMxY-0006Wf-14; Fri, 16 Oct 2020 10:27:40 +0000 Received: from foss.arm.com ([217.140.110.172]) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kTMxU-0006VY-J5 for linux-arm-kernel@lists.infradead.org; Fri, 16 Oct 2020 10:27:37 +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 8CDA7D6E; Fri, 16 Oct 2020 03:27:28 -0700 (PDT) Received: from [192.168.0.130] (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id A75FA3F719; Fri, 16 Oct 2020 03:27:26 -0700 (PDT) Subject: Re: [PATCH] arm64: mm: account for hotplug memory when randomizing the linear region To: Will Deacon , Ard Biesheuvel References: <20201014081857.3288-1-ardb@kernel.org> <20201015104636.GA5064@willie-the-truck> From: Anshuman Khandual Message-ID: <41f35718-a299-fb33-2b05-d1c029c025f9@arm.com> Date: Fri, 16 Oct 2020 15:56:41 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20201015104636.GA5064@willie-the-truck> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201016_062736_684913_C1F3F0DC X-CRM114-Status: GOOD ( 17.67 ) 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: Catalin Marinas , Robin Murphy , linux-arm-kernel@lists.infradead.org, Steven Price 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 On 10/15/2020 04:16 PM, Will Deacon wrote: > On Wed, Oct 14, 2020 at 10:18:57AM +0200, Ard Biesheuvel wrote: >> As a hardening measure, we currently randomize the placement of >> physical memory inside the linear region when KASLR is in effect. >> Since the random offset at which to place the available physical >> memory inside the linear region is chosen early at boot, it is >> based on the memblock description of memory, which does not cover >> hotplug memory. The consequence of this is that the randomization >> offset may be chosen such that any hotplugged memory located above >> memblock_end_of_DRAM() that appears later is pushed off the end of >> the linear region, where it cannot be accessed. >> >> So let's limit this randomization of the linear region to ensure >> that this can no longer happen, by using the CPU's addressable PA >> range instead. As it is guaranteed that no hotpluggable memory will >> appear that falls outside of that range, we can safely put this PA >> range sized window anywhere in the linear region. >> >> Cc: Anshuman Khandual >> Cc: Catalin Marinas >> Cc: Will Deacon >> Cc: Steven Price >> Cc: Robin Murphy >> Signed-off-by: Ard Biesheuvel >> --- >> Related to discussion here: >> https://lore.kernel.org/linux-arm-kernel/1600332402-30123-1-git-send-email-anshuman.khandual@arm.com/ > > Anshuman, can you fold this one into your series, please? Sure, will do. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel