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=-15.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=unavailable 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 D0561C433E0 for ; Mon, 15 Feb 2021 05:27:29 +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 69B5C64E51 for ; Mon, 15 Feb 2021 05:27:29 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 69B5C64E51 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:List-Subscribe:List-Help:List-Post:List-Archive:List-Unsubscribe :List-Id:In-Reply-To:MIME-Version:Date:Message-ID:References:To:Subject:From: Reply-To:Cc:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=QNJhgGY2wPRjY/7KeJBcbYP0o1+7VGIsS9fM0VOj0gE=; b=Uk5AJzuT6uJ/sJ71lNmhP7/3YM EeZY3P8AnPEHULB23VxP25/rEIr5L6RwgloBeC80T2zcfvK4sPId8c7Nns0t14B0E8XYfBTiBZEMl kWvo3ZZbSjZRjWZLzPn25HfWI6OAbMv9aXJi8UcYxK2pqdKtwGIlPKSf/xy86/HupQEvRAFTruG+t B5+vCYBAfz+cNaiIj+zjVF6KIGKE5Xu9ydFTFTm71avDQ2wXBYLxKdjvFg6t//U1cE7CJhvPB+Fqm NRGHMtbNmUGMhmlEb2icaZ/DPzbJqiYnkBCzICOYoIaa82bGpFpTrIkY56XhE9vIhGQjMw68JLWu0 GDZOdJUA==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1lBWOt-0004Mb-5I; Mon, 15 Feb 2021 05:26:23 +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 1lBWOq-0004M0-Gw for linux-arm-kernel@lists.infradead.org; Mon, 15 Feb 2021 05:26:21 +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 C7718101E; Sun, 14 Feb 2021 21:26:16 -0800 (PST) Received: from [192.168.0.130] (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 4487E3F73B; Sun, 14 Feb 2021 21:26:12 -0800 (PST) From: Anshuman Khandual Subject: Re: [PATCH] arm64: mm: correct the start of physical address in linear map To: Pavel Tatashin , tyhicks@linux.microsoft.com, jmorris@namei.org, catalin.marinas@arm.com, will@kernel.org, akpm@linux-foundation.org, rppt@kernel.org, logang@deltatee.com, ardb@kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org References: <20210213012316.1525419-1-pasha.tatashin@soleen.com> Message-ID: <06b7bfd1-99cd-a9be-e3cc-9fe13f2cf2a6@arm.com> Date: Mon, 15 Feb 2021 10:56:15 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20210213012316.1525419-1-pasha.tatashin@soleen.com> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210215_002620_701608_31B4F52D X-CRM114-Status: GOOD ( 26.27 ) 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: , 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 Hello Pavel, On 2/13/21 6:53 AM, Pavel Tatashin wrote: > Memory hotplug may fail on systems with CONFIG_RANDOMIZE_BASE because the > linear map range is not checked correctly. > > The start physical address that linear map covers can be actually at the > end of the range because of randmomization. Check that and if so reduce it > to 0. Looking at the code, this seems possible if memstart_addr which is a signed value becomes large (after falling below 0) during arm64_memblock_init(). > > This can be verified on QEMU with setting kaslr-seed to ~0ul: > > memstart_offset_seed = 0xffff > START: __pa(_PAGE_OFFSET(vabits_actual)) = ffff9000c0000000 > END: __pa(PAGE_END - 1) = 1000bfffffff > > Signed-off-by: Pavel Tatashin > Fixes: 58284a901b42 ("arm64/mm: Validate hotplug range before creating linear mapping") > --- > arch/arm64/mm/mmu.c | 15 +++++++++++++-- > 1 file changed, 13 insertions(+), 2 deletions(-) > > diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c > index ae0c3d023824..6057ecaea897 100644 > --- a/arch/arm64/mm/mmu.c > +++ b/arch/arm64/mm/mmu.c > @@ -1444,14 +1444,25 @@ static void __remove_pgd_mapping(pgd_t *pgdir, unsigned long start, u64 size) > > static bool inside_linear_region(u64 start, u64 size) > { > + u64 start_linear_pa = __pa(_PAGE_OFFSET(vabits_actual)); > + u64 end_linear_pa = __pa(PAGE_END - 1); > + > + /* > + * Check for a wrap, it is possible because of randomized linear mapping > + * the start physical address is actually bigger than the end physical > + * address. In this case set start to zero because [0, end_linear_pa] > + * range must still be able to cover all addressable physical addresses. > + */ If this is possible only with randomized linear mapping, could you please add IS_ENABLED(CONFIG_RANDOMIZED_BASE) during the switch over. Wondering if WARN_ON(start_linear_pa > end_linear_pa) should be added otherwise i.e when linear mapping randomization is not enabled. > + if (start_linear_pa > end_linear_pa) > + start_linear_pa = 0; This looks okay but will double check and give it some more testing. > + > /* > * Linear mapping region is the range [PAGE_OFFSET..(PAGE_END - 1)] > * accommodating both its ends but excluding PAGE_END. Max physical > * range which can be mapped inside this linear mapping range, must > * also be derived from its end points. > */ > - return start >= __pa(_PAGE_OFFSET(vabits_actual)) && > - (start + size - 1) <= __pa(PAGE_END - 1); > + return start >= start_linear_pa && (start + size - 1) <= end_linear_pa; > } > > int arch_add_memory(int nid, u64 start, u64 size, > - Anshuman _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel