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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id B167EC4332F for ; Fri, 18 Nov 2022 14:14:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc: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=16RU+D8aH6lCvl7kr92hTJSnX+zWbxBrhqNagRrz0BY=; b=NekZ7wYW/eoRZ+ F56sHzxgxA74ocK05dr5QnbekLi/E42Dz37xCN4AlvB6IwWXRrkvefvDBq+SVIRhpwsoJCk8YJjib AKSZX6uJWWeZy/GaxKPQl2oM5U0xsY89tdlMQLLT59+DbocUN/3MGXIr+f7el0JDXRWvcBHV3JNmI yBZSdOUZmWJytE/w5hTw4NxibeG/tTLQQMIZPJnaVt6sDdHk5ZNpErKFb1YOVj6Rx7t7Dq256h3oI y7sV0/NPpiZS4lz5qexTrOvVuzSfWGeHbNvPihM+AZgl6qOHUbo28dU4dOSZx74OIRd4I1oyWCSEw BTFddvhScA03BiUCk+og==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1ow27T-004Kyg-0v; Fri, 18 Nov 2022 14:13:27 +0000 Received: from dfw.source.kernel.org ([2604:1380:4641:c500::1]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1ow27Q-004KxK-83 for linux-arm-kernel@lists.infradead.org; Fri, 18 Nov 2022 14:13:25 +0000 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 9D78B62559; Fri, 18 Nov 2022 14:13:23 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C9015C433C1; Fri, 18 Nov 2022 14:13:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1668780803; bh=JCjICSm8pXwo9orCVyEXmyIQs3uhVXt10DDdNuRS6yw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=o34jLMToHAJQaDuVlBaqdI6ZPbgtVBeVlmHtaPkN3vcCL/zcek2FNP2mGC+mjdlzE iqVjbPgqRBnQWBzZ9oht3OodMPHlycjaR0HNDfZok/Ly6aZVv0X8fYoJn6fLffg5i3 xzE6fvlZH/AdtQBzLauYdUlh/YDCtW5EDS3bg+5HeirZJGFVMfF/JFM55z7kzHfsfu 5p5gIbJCXHXiMym6GENIYbgI/zGmULbn+5YmdROvHqT9IUwdGzyjtWbEs2uZg2PLuq 5BD07dSI5P3rQ5NiTXGsxXB3D9cZQjkWs9RFFunXJ8ikPdsSSbHtLLJwWsD04LOp0C DHhYbVEFkXU5g== Date: Fri, 18 Nov 2022 14:13:18 +0000 From: Will Deacon To: Anshuman Khandual Cc: linux-arm-kernel@lists.infradead.org, catalin.marinas@arm.com, Mark Rutland , Andrew Morton , linux-kernel@vger.kernel.org Subject: Re: [PATCH] arm64/mm: Intercept pfn changes in set_pte_at() Message-ID: <20221118141317.GF4046@willie-the-truck> References: <20221116031001.292236-1-anshuman.khandual@arm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20221116031001.292236-1-anshuman.khandual@arm.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20221118_061324_339600_F5215944 X-CRM114-Status: GOOD ( 15.98 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 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 On Wed, Nov 16, 2022 at 08:40:01AM +0530, Anshuman Khandual wrote: > Changing pfn on a user page table mapped entry, without first going through > break-before-make (BBM) procedure is unsafe. This just updates set_pte_at() > to intercept such changes, via an updated pgattr_change_is_safe(). This new > check happens via __check_racy_pte_update(), which has now been renamed as > __check_safe_pte_update(). > > Cc: Catalin Marinas > Cc: Will Deacon > Cc: Mark Rutland > Cc: Andrew Morton > Cc: linux-arm-kernel@lists.infradead.org > Cc: linux-kernel@vger.kernel.org > Signed-off-by: Anshuman Khandual > --- > This applies on v6.1-rc4 > > arch/arm64/include/asm/pgtable.h | 8 ++++++-- > arch/arm64/mm/mmu.c | 8 +++++++- > 2 files changed, 13 insertions(+), 3 deletions(-) I remember Mark saying that BBM is sometimes violated by the core code in cases where the pte isn't actually part of a live pgtable (e.g. if it's on the stack or part of a newly allocated table). Won't that cause false positives here? Will _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel