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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,UNPARSEABLE_RELAY 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 19487C43387 for ; Wed, 9 Jan 2019 01:35:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DC89A20821 for ; Wed, 9 Jan 2019 01:35:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729327AbfAIBf0 (ORCPT ); Tue, 8 Jan 2019 20:35:26 -0500 Received: from mailgw02.mediatek.com ([210.61.82.184]:30801 "EHLO mailgw02.mediatek.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1729067AbfAIBfZ (ORCPT ); Tue, 8 Jan 2019 20:35:25 -0500 X-UUID: 6270caafbefa46bdafaf1b4758890335-20190109 X-UUID: 6270caafbefa46bdafaf1b4758890335-20190109 Received: from mtkmrs01.mediatek.inc [(172.21.131.159)] by mailgw02.mediatek.com (envelope-from ) (mhqrelay.mediatek.com ESMTP with TLS) with ESMTP id 346372565; Wed, 09 Jan 2019 09:35:19 +0800 Received: from mtkcas07.mediatek.inc (172.21.101.84) by mtkmbs08n2.mediatek.inc (172.21.101.56) with Microsoft SMTP Server (TLS) id 15.0.1395.4; Wed, 9 Jan 2019 09:35:17 +0800 Received: from MTKCAS06.mediatek.inc (172.21.101.30) by mtkcas07.mediatek.inc (172.21.101.84) with Microsoft SMTP Server (TLS) id 15.0.1395.4; Wed, 9 Jan 2019 09:35:17 +0800 Received: from [172.21.77.33] (172.21.77.33) by MTKCAS06.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.0.1395.4 via Frontend Transport; Wed, 9 Jan 2019 09:35:17 +0800 Message-ID: <1546997717.20937.3.camel@mtkswgap22> Subject: Re: [PATCH] arm64: trap illegal translations in __virt_to_phys() From: Miles Chen To: Mark Rutland CC: Catalin Marinas , Will Deacon , , , , Date: Wed, 9 Jan 2019 09:35:17 +0800 In-Reply-To: <20190108121440.GC29102@lakrids.cambridge.arm.com> References: <1546860080-13027-1-git-send-email-miles.chen@mediatek.com> <20190107150019.GC46743@lakrids.cambridge.arm.com> <1546917883.6754.8.camel@mtkswgap22> <20190108121440.GC29102@lakrids.cambridge.arm.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.2.3-0ubuntu6 Content-Transfer-Encoding: 7bit MIME-Version: 1.0 X-MTK: N X-TM-SNTS-SMTP: A3E3E476657A8AEA9A3F13BDF29E0B0E7871C13BB2A5D93DBCA9E749BAB92D162000:8 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2019-01-08 at 12:14 +0000, Mark Rutland wrote: > On Tue, Jan 08, 2019 at 11:24:43AM +0800, Miles Chen wrote: > > On Mon, 2019-01-07 at 15:00 +0000, Mark Rutland wrote: > > > On Mon, Jan 07, 2019 at 07:21:20PM +0800, Miles Chen wrote: > > > > Current __virt_to_phys() only print warning messages for non-linear > > > > addresses. It's hard to catch all warnings by those messages. > > > > > > Why? Are you seeing a large number of warnings somewhere? > > > > Official kernel works fine. I saw some cases in our internal branch and > > we're fixing them. > > > > > > > > > So add a VIRTUAL_BUG_ON() to trap all non-linear and non-symbol > > > > addresses (e.g., stack addresses) > > > > > > > > Tested by pass stack addresses and symbol addresses to __pa(). Result: > > > > stack addresses: kernel BUG() > > > > > > Either: > > > > > > * Stacks are vmap'd, and __is_lm_address(stack_addr) is false. We'll > > > produce a WARNING() today (and return a junk physical address). > > > > > > * Stacks are linear mapped, and cannot be distinguished from other > > > linear mapped addresses. The physical address will be valid. > > > > > > ... so I don't understand why you need to change this. > > > > For the first case: for vmap'd stack, __pa() returns a junk > > physical address and it might be easier to debug this incorrect address > > translation by a BUG() call instead of monitoring the warning log. > > I think that's an argument for upgrading the existing WARN() to a BUG(), > rather than adding a separate VIRTUAL_BUG_ON(). > > However, there are cases where the junk physical address is not used to > perform an access, and the WARN() is more helpful. got it. > > You can set panic_on_warn to get an immediate panic() when the WARN() > fires. Is there some reason that approach doesn't work for you? panic_on_warn works fine. thanks for your comment. cheers, Miles > > Thanks, > Mark.