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=-3.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=no 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 48572C43463 for ; Fri, 18 Sep 2020 12:36:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0DE752073A for ; Fri, 18 Sep 2020 12:36:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726587AbgIRMgm (ORCPT ); Fri, 18 Sep 2020 08:36:42 -0400 Received: from mout.kundenserver.de ([212.227.17.10]:39563 "EHLO mout.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726154AbgIRMgl (ORCPT ); Fri, 18 Sep 2020 08:36:41 -0400 Received: from mail-qt1-f174.google.com ([209.85.160.174]) by mrelayeu.kundenserver.de (mreue106 [212.227.15.145]) with ESMTPSA (Nemesis) id 1MHnZQ-1kEI5W0sgo-00EwgF; Fri, 18 Sep 2020 14:36:40 +0200 Received: by mail-qt1-f174.google.com with SMTP id c18so4778666qtw.5; Fri, 18 Sep 2020 05:36:39 -0700 (PDT) X-Gm-Message-State: AOAM531P0vWhxtgLTyK/ASRNZLNtY2deNYX1PrkvlZCh/JM48cL9Dvn6 T18/2j/SPvdHteGseUUOwrA0KNaOt5vmJGNzI50= X-Google-Smtp-Source: ABdhPJzHuJZ/kDocyLlLrnh1ExNrKpMLkiEpPLdi9PahWckRQnAPVIMevhGijaQB/J930L15teODRXzI8m5Cr7Nw24M= X-Received: by 2002:aed:2ce5:: with SMTP id g92mr19928608qtd.204.1600432598903; Fri, 18 Sep 2020 05:36:38 -0700 (PDT) MIME-Version: 1.0 References: <20200907153701.2981205-1-arnd@arndb.de> <20200907153701.2981205-3-arnd@arndb.de> <20200908061528.GB13930@lst.de> <20200918074203.GU1551@shell.armlinux.org.uk> In-Reply-To: <20200918074203.GU1551@shell.armlinux.org.uk> From: Arnd Bergmann Date: Fri, 18 Sep 2020 14:36:23 +0200 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH 2/9] ARM: traps: use get_kernel_nofault instead of set_fs() To: Russell King - ARM Linux admin Cc: Christoph Hellwig , Alexander Viro , linux- , linux-arch , Linux ARM , Linus Walleij , Andrew Morton , Dmitry Safonov <0x7f454c46@gmail.com>, "linux-kernel@vger.kernel.org" Content-Type: text/plain; charset="UTF-8" X-Provags-ID: V03:K1:uQ1rd98AYHFYnsPXe5sEe/Tx2b86dN9VTdMt61Zxci4xR1f6u9Q Jc23I9AKuaf4UPWMeRYcxl0y/tYsKix6NuDCa1AJsfZpOD0PCpSow/tBshCWbiIFTN9yGH7 7qxsVPFnmaCs1Cf4cDvIk0Cb0CFCNeQWP2S27bXdNG4xvlQLRYPDfj/6YC2Dxu/bNOA3kXk vNDDT7JNV3birPxddl8KQ== X-UI-Out-Filterresults: notjunk:1;V03:K0:tPEtwy/3JPA=:EazmA3FpyPiDwBxPKg+o3Z JesvTBW0cDHRKN0QRoNwGwxkwA8EhckldC2H6hUH12TEH/mkTXBoEur1LIWWmjL1+iaJeAfVx mFSt9UE8nZoC9ocVSOJD88GyNbPUPJ0VZCSaRP76v3w/3EB95HCaWeLmW3+IBtm7NonCL8+qK e95OeX0c2JB47/Pkw704dF5g8vwH/MwuCh5it/MDoiGHBInauCMeW9EAkH5LUI4z8wj3AvsxG zxyzri8LI/LpejNNc9DYBHJeuauNVnHsjEkYX82pbB2RQqNqbQGaLns0IzCVr8OBhq/OpyInD dVIoH52N+wC8G5JGHxGbu/RwK3hVRCU5fS0tUAR86ULsF/jQAeD5PBIIc/M7qycmW2PHUIFgA VRJczQ9WiS0AmhYSwJ9Ox67HdjiC6Hh7XPxTgAxED1VqX2ytDdJ8DkLMmm25iN5YddIkkhj/y zmMsfhFb0G64V5Z9nQ0hGxeiuIVlu6A4RTmJYTpT5njc6LWJUXae8wMF0AbClZFO4XFQs7dCc BNYqWikmJ/w7gGO6VlWQFiNXTPv7Sa3Lk6lA2cQTtJiTgdpS8P0WnZ8LrPc9E2+xASr/Npuya smsRCLxqdynTNS7kWwnQFF3/1vl55GzkI8aCZj3bIqYVKriUVckPlVnln6K2WKuGnq29L0ZEt 7MXWgLiIxtwdkk0WAIJdr/3lhwv67UtlYnR14bM+pyixV/21LPrEmgc+Xi9b47qPQD8IfKZMM eyDFWiFRRTqEQzhJ+uT4P1UGVwD4avKaPDUeuRdg5wWRZ9FVQ89Y+WKdK5R3ys0oR7zXyhJcx vjcMJpoQJK79Ab/i7yh5VWJJhrQS2hgcMlvttXrGKb+nwZPTdKlCEBWNvP7PTjyx+OlCc86 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Sep 18, 2020 at 9:42 AM Russell King - ARM Linux admin wrote: > > On Thu, Sep 17, 2020 at 07:29:37PM +0200, Arnd Bergmann wrote: > > On Tue, Sep 8, 2020 at 8:15 AM Christoph Hellwig wrote: > > > > I looked through the history now and the only code path I could > > find that would arrive here this way is from bad_mode(), indicating > > that there is probably a hardware bug or the contents of *regs are > > corrupted. > > Yes, that's correct. It isn't something entirely theoretical, although > we never see it now, it used to happen in the distant past due to saved > regs corruption. If bad_mode() ever gets called, all bets are off and > we're irrecoverably crashing. > > Note that in that case, while user_mode(regs) may return true or false, > regs->ARM_sp and regs->ARM_lr are always the SVC mode stack and return > address after regs has been stacked, and not the expected values for > the parent context (which we have most likely long since destroyed.) Ok, I have rewritten the patch and my changelog text accordingly, sending an updated version now. Thanks, Arnd