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=-8.4 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,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 1C4C1C55186 for ; Wed, 22 Apr 2020 23:54:23 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id 6EF2D206ED for ; Wed, 22 Apr 2020 23:54:22 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="ul4AvjVQ" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6EF2D206ED Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kernel-hardening-return-18613-kernel-hardening=archiver.kernel.org@lists.openwall.com Received: (qmail 23917 invoked by uid 550); 22 Apr 2020 23:54:16 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Received: (qmail 23894 invoked from network); 22 Apr 2020 23:54:16 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=9yta31YHLGTtMTc3kimrMC0tNHi4fPt9ZpXXfvJokHE=; b=ul4AvjVQXbGe+67+07L6i6vBhv+ePFHnNv5wOIO5OLBqKwlga7zXiy6xS1d0X/n/tF 6woOlNdImmOPZMJChQsUQyygz5ZseUPmnZAKczKpT7Y7lInJ6k/DDJqqloDP2VpGFDPw OFtrm1ALOx3/hCMPr/YQ3m1N7xm3tLJ/pl95K3DRTQoOWwlka1VKxTJhNX6t7x3uramm 2dyep6SUwSuJ79qzMc80b3OzgAHRlzEcC+sG84d0mATYPxu/tkZ16ivMuXJA1CHS9gCY zZTcPJxWLKTN7QTPUPa2eVcTdjKumsRqOxjD1k+RVCHPaHKtuxR9qW1L8MlMmMCCFv+Y LkDg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=9yta31YHLGTtMTc3kimrMC0tNHi4fPt9ZpXXfvJokHE=; b=PxMKnFvKkIOfCVTLDeDH/+qu6A8CKKL5ebEdLrLBw8R5ayM89fi6ab92VQdd5OEbQU XYBRzKFvGumqL97PqZjYXu7ZF+NuHgZYpFknemck4tMv8keW9t+kffAFYkZVX4yPcAx5 BnwD94h2MZ4o2ZAwiMomP4WKH0rWUcuorsyT4QUeaaIah5ZzT5VEgHEs+8bV0cI1Otmt tt2WIdbqGNg8pWKIeww5y9W1vjtXlNv7qkTQ1bfUmCddRAMnyh6BBeOdXhb4mIq/avhk 0DrVrzY4diLtoQ66CLoi7P5pJoEFbY2bn75gV9+ppPX3311DOKb1I2oQt65GX0NC5X4K BiUw== X-Gm-Message-State: AGi0PubVdXpC7OcEnGUh9ocjCKDla5S2rF0jVEB+HsnHHnQRtqQtO3jB YZhyuMUOXxKU1u+gKI1jmEw6fw== X-Google-Smtp-Source: APiQypIxgD2CWLnytM507AIaoaby+Reth9qe8JpsU5Egogw5Wrog+ZS/v8kJIWI3ShghE5eGkNfP8g== X-Received: by 2002:aa7:8118:: with SMTP id b24mr1011016pfi.321.1587599643609; Wed, 22 Apr 2020 16:54:03 -0700 (PDT) Date: Wed, 22 Apr 2020 16:53:56 -0700 From: Sami Tolvanen To: Will Deacon Cc: Catalin Marinas , James Morse , Steven Rostedt , Ard Biesheuvel , Mark Rutland , Masahiro Yamada , Michal Marek , Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Dave Martin , Kees Cook , Laura Abbott , Marc Zyngier , Masami Hiramatsu , Nick Desaulniers , Jann Horn , Miguel Ojeda , clang-built-linux@googlegroups.com, kernel-hardening@lists.openwall.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v12 03/12] scs: add support for stack usage debugging Message-ID: <20200422235356.GA128062@google.com> References: <20191018161033.261971-1-samitolvanen@google.com> <20200421021453.198187-1-samitolvanen@google.com> <20200421021453.198187-4-samitolvanen@google.com> <20200422174602.GB3121@willie-the-truck> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200422174602.GB3121@willie-the-truck> On Wed, Apr 22, 2020 at 06:46:02PM +0100, Will Deacon wrote: > > +static void scs_check_usage(struct task_struct *tsk) > > +{ > > + static unsigned long highest; > > + unsigned long used = __scs_used(tsk); > > + unsigned long prev; > > + unsigned long curr = highest; > > + > > + while (used > curr) { > > + prev = cmpxchg(&highest, curr, used); > > I think this can be cmpxchg_relaxed(), since we don't care about ordering > here afaict. Sure, I'll change this in v13. Thanks. Sami