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=-8.5 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 A9819C54FCB for ; Wed, 22 Apr 2020 17:46:16 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 81CA721556 for ; Wed, 22 Apr 2020 17:46:16 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="Qe3N8Hf4"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="xeCqLIAI" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 81CA721556 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject: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=E8YR5mRKZ2nhJHlWxVhpCC1siMCeC8kn8RxA9RaVobc=; b=Qe3N8Hf4h4qBlU i7N/z6eRvo9stRjPYTe4hwKykw76q/mzOc/BN9hG9w8gQONMpA1Orqai7zqPJz48SmPS8H0HG72nS YmGjvOV8jldrIFFC1gEwE9ofieMqQZl9VOfd27aVt2XR0W8DZoQ3mY/ZsKJ7ZYuPVYKzZ3WpJeZv+ E73J0dXd8r9QBN93qwjV8bF3iMJNAUN5MxFN+cWwADno8ngqecs4wPuTaLUOa9kS5XlpRvOqJvobm ZyCop4Wdes/SFrIId5Io061opGecUkZZBLw6HRCVs2yvoNjoBBRfZExjCy00KK9CvGq8XZRkDQEF/ Iu960NlZO3QYyZR3kW/A==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jRJRt-0005gV-Kt; Wed, 22 Apr 2020 17:46:13 +0000 Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1jRJRp-0005fX-Ol for linux-arm-kernel@lists.infradead.org; Wed, 22 Apr 2020 17:46:11 +0000 Received: from willie-the-truck (236.31.169.217.in-addr.arpa [217.169.31.236]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id C61B420882; Wed, 22 Apr 2020 17:46:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1587577569; bh=BZ6+GxqnknwEXTVUtex2UCZYN1TnyT2nFbqPEZvID5Q=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=xeCqLIAIf4jizG2Ckht2qwltfYk8W5t7dkqurW5+DudPXgEs52Se1z8kA6BYPOJvg zWeehGFavyojT3LhGVeOWARgj6LEsxC0YHGvVxWT4c7cDFTYsZV2It6kXt09f/QSfF HpAJI7pNWvgcdxfndttxPkynvgEj5eZLoxc5MmEQ= Date: Wed, 22 Apr 2020 18:46:02 +0100 From: Will Deacon To: Sami Tolvanen Subject: Re: [PATCH v12 03/12] scs: add support for stack usage debugging Message-ID: <20200422174602.GB3121@willie-the-truck> References: <20191018161033.261971-1-samitolvanen@google.com> <20200421021453.198187-1-samitolvanen@google.com> <20200421021453.198187-4-samitolvanen@google.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200421021453.198187-4-samitolvanen@google.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-20200422_104609_830744_B7DEE240 X-CRM114-Status: GOOD ( 15.59 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , Juri Lelli , kernel-hardening@lists.openwall.com, Peter Zijlstra , Catalin Marinas , Marc Zyngier , Masahiro Yamada , clang-built-linux@googlegroups.com, Ingo Molnar , Laura Abbott , Dave Martin , Kees Cook , Jann Horn , Steven Rostedt , linux-arm-kernel@lists.infradead.org, Michal Marek , Ard Biesheuvel , Nick Desaulniers , linux-kernel@vger.kernel.org, Miguel Ojeda , James Morse , Masami Hiramatsu Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, Apr 20, 2020 at 07:14:44PM -0700, Sami Tolvanen wrote: > Implements CONFIG_DEBUG_STACK_USAGE for shadow stacks. When enabled, > also prints out the highest shadow stack usage per process. > > Signed-off-by: Sami Tolvanen > Reviewed-by: Kees Cook > --- > kernel/scs.c | 38 ++++++++++++++++++++++++++++++++++++++ > 1 file changed, 38 insertions(+) > > diff --git a/kernel/scs.c b/kernel/scs.c > index 7eea2d97bd2d..147917e31adf 100644 > --- a/kernel/scs.c > +++ b/kernel/scs.c > @@ -68,6 +68,43 @@ int scs_prepare(struct task_struct *tsk, int node) > return 0; > } > > +#ifdef CONFIG_DEBUG_STACK_USAGE > +static unsigned long __scs_used(struct task_struct *tsk) > +{ > + unsigned long *p = __scs_base(tsk); > + unsigned long *end = __scs_magic(p); > + unsigned long s = (unsigned long)p; > + > + while (p < end && READ_ONCE_NOCHECK(*p)) > + p++; > + > + return (unsigned long)p - s; > +} > + > +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. With that: Acked-by: Will Deacon Cheers, Will _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel