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=-14.4 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_IN_DEF_DKIM_WL 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 9AEF5C4363D for ; Fri, 25 Sep 2020 11:26:16 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 389DE221EB for ; Fri, 25 Sep 2020 11:26:16 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="AQUMaA2m" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 389DE221EB Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id D06D7900007; Fri, 25 Sep 2020 07:26:15 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id C8FD38E0001; Fri, 25 Sep 2020 07:26:15 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id B7EB9900007; Fri, 25 Sep 2020 07:26:15 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 9DCCF8E0001 for ; Fri, 25 Sep 2020 07:26:15 -0400 (EDT) Received: from smtpin07.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 6647E8249980 for ; Fri, 25 Sep 2020 11:26:15 +0000 (UTC) X-FDA: 77301355110.07.brake51_4a112c527167 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin07.hostedemail.com (Postfix) with ESMTP id 4697A1803FF14 for ; Fri, 25 Sep 2020 11:26:15 +0000 (UTC) X-HE-Tag: brake51_4a112c527167 X-Filterd-Recvd-Size: 5136 Received: from mail-pf1-f195.google.com (mail-pf1-f195.google.com [209.85.210.195]) by imf47.hostedemail.com (Postfix) with ESMTP for ; Fri, 25 Sep 2020 11:26:14 +0000 (UTC) Received: by mail-pf1-f195.google.com with SMTP id x22so2848464pfo.12 for ; Fri, 25 Sep 2020 04:26:14 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=WxOkTxBUdDygkxQk8SSiZ/3m/eISYyIoxaAPO6Ft/3c=; b=AQUMaA2mUShicKX0LRfMzsr/JU4gyntiGkqnwNgVDtq5RxgOdRJLGETYAXd5xTEiha bkFx4pWFNuxAM5KWfR8fJ0P3dKruvwdZysZ8dGOlBYOdxgWkSkBUajMVVTCdYXWX10xi eAeQ1w5Ke4tzvSKmBMyJHC6GQfKNCKV0QICTJKjT2oLSXH6i34fknlc2pNy973sduyEv 2O3BeqTW+vZ+wz2SeDFR0nvjpyP+9/av1GJgF05yKru8G5tiGqRqIoRIiAX3cPJ5FDJ0 c8dgXhECbxM+mL+VNPhxP+d5+SdFSsxiAIZqbeUgjVeQTbCBUIAfYzPGXHDHtk6N+n3X wcWw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=WxOkTxBUdDygkxQk8SSiZ/3m/eISYyIoxaAPO6Ft/3c=; b=XHfnzxzOmxkDPFHxQxLFF6eJdm0OpQbPHrgpkHbotwX+hf+JPy9CYJ96yhCUwiOgRl xczX3J1RyZAQvGgJFZ4cwaz12jZhZQ7GU4ILeGSUC/tdBo36053S+SbxPLJqferjVVm9 T4A1F40Hy1dqPLkTPk/tD7q4ohn5902c9BmaruLMvSQo4YZtcLxzalmwJRCaQUGz2w3b RcU6N7D9kvs0Sd72lxOa7NDUisT858tLMJrcGdqIx0n8HW4QbFixPVtnwYSBXpsTYSZk xV1yDlu1oyZeA3SADuNW/+MWJPOmvcrq6iP0KGx0ZG8L7mbddI1joilpTzIhtExJdI35 r78g== X-Gm-Message-State: AOAM532PlP63lup74RdbkGqsk4oNM0mvwZ/SNtpj4/U2RQEukfgBo0mI /B9NRxs6iqdE0C3ENlBmAOT6h3JVllLndpbKimAckA== X-Google-Smtp-Source: ABdhPJwfze/WXqXUgMMG8rf/dj3TrYc3bE53uc/cJm5bp9cbbzOGtFOvfgTZBQCcxs/GOFoexk6G5UC8GjCHrp+FuBY= X-Received: by 2002:a62:1d51:0:b029:13e:d13d:a0fc with SMTP id d78-20020a621d510000b029013ed13da0fcmr3806915pfd.24.1601033173658; Fri, 25 Sep 2020 04:26:13 -0700 (PDT) MIME-Version: 1.0 References: <17ec8af55dc0a4d3ade679feb0858f0df4c80d27.1600987622.git.andreyknvl@google.com> <20200925104933.GD4846@gaia> In-Reply-To: <20200925104933.GD4846@gaia> From: Andrey Konovalov Date: Fri, 25 Sep 2020 13:26:02 +0200 Message-ID: Subject: Re: [PATCH v3 26/39] arm64: mte: Add in-kernel tag fault handler To: Catalin Marinas Cc: Dmitry Vyukov , Vincenzo Frascino , kasan-dev , Andrey Ryabinin , Alexander Potapenko , Marco Elver , Evgenii Stepanov , Elena Petrova , Branislav Rankov , Kevin Brodsky , Will Deacon , Andrew Morton , Linux ARM , Linux Memory Management List , LKML Content-Type: text/plain; charset="UTF-8" X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, Sep 25, 2020 at 12:49 PM Catalin Marinas wrote: > > > diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c > > index a3bd189602df..d110f382dacf 100644 > > --- a/arch/arm64/mm/fault.c > > +++ b/arch/arm64/mm/fault.c > > @@ -33,6 +33,7 @@ > > #include > > #include > > #include > > +#include > > #include > > #include > > #include > > @@ -294,6 +295,11 @@ static void die_kernel_fault(const char *msg, unsigned long addr, > > do_exit(SIGKILL); > > } > > > > +static void report_tag_fault(unsigned long addr, unsigned int esr, > > + struct pt_regs *regs) > > +{ > > +} > > Do we need to introduce report_tag_fault() in this patch? It's fine but > add a note in the commit log that it will be populated in a subsequent > patch. I did, see the last line of the commit description. > > + > > static void __do_kernel_fault(unsigned long addr, unsigned int esr, > > struct pt_regs *regs) > > { > > @@ -641,10 +647,40 @@ static int do_sea(unsigned long addr, unsigned int esr, struct pt_regs *regs) > > return 0; > > } > > > > +static void do_tag_recovery(unsigned long addr, unsigned int esr, > > + struct pt_regs *regs) > > +{ > > + static bool reported = false; > > + > > + if (!READ_ONCE(reported)) { > > + report_tag_fault(addr, esr, regs); > > + WRITE_ONCE(reported, true); > > + } > > I don't mind the READ_ONCE/WRITE_ONCE here but not sure what they help > with. The fault can happen on multiple cores at the same time, right? In that case without READ/WRITE_ONCE() we'll have a data-race here.