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=-5.6 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 44200C433DB for ; Mon, 1 Feb 2021 21:41:31 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (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 E891164D87 for ; Mon, 1 Feb 2021 21:41:30 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E891164D87 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.microsoft.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+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=merlin.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:Date:Message-ID:From: References:To:Subject:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=cMp4lZRVUbyosIpyWw1Oo4Hafsrq1hTGqYbGEM/QKOM=; b=glOweHZWnCij/hHbxyB63Yn65 8PeD115Sv7YSbCYnnIaUdjsi4yaCYBDgY3ss1A/ntSerAculF8q85oloUqWqyyZE/RwZHWDc84ahX axjpYoRp9UfK7qoPF8C67mMCOzpFn1heY9PWZrmf0toWNkfANwcRUyPkFKfXDjYkGzHiJ/ZOMgAyo 7km3R1VoyRdiWqlOvqZwKSwbXq+ErBxsI1JAiT682fUkqVGwLLck4f9flQBxX/rWltWIaA0tJD28p tc/ZYVAHeEGbW6I7Q8kn13GJyy9EcYGsk3HE1DSZ6K3Lhvmg80GUGLKfUWHHfbqLDmEPfKQU3RO85 yWZWoMXcw==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1l6gvm-00041g-Ox; Mon, 01 Feb 2021 21:40:22 +0000 Received: from linux.microsoft.com ([13.77.154.182]) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1l6gvj-00040s-BU for linux-arm-kernel@lists.infradead.org; Mon, 01 Feb 2021 21:40:21 +0000 Received: from [192.168.254.32] (unknown [47.187.219.45]) by linux.microsoft.com (Postfix) with ESMTPSA id DBB8820B7192; Mon, 1 Feb 2021 13:40:16 -0800 (PST) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com DBB8820B7192 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1612215617; bh=4zktaG8W0bmd3hI8wy3QoVtcJJ/mc4RueAAs2Dqm3bk=; h=Subject:To:Cc:References:From:Date:In-Reply-To:From; b=s8kucq1k8OIXvWFQxjeTUeWTXLQY2TtZvSGXfqDNwSWjq8DQodKUVwCS/VoVCBTjF xVxuu1CiOITU5tVJg46P/2om67T8EP+jZiCeGgEB7RbjxzRhd7Sr+F8ySX/BuqfzDn LHN7aEZQEc4SF9IbYvEWdhG0SMQYP29uqkWc8vBw= Subject: Re: [RFC PATCH 0/3] arm64: Implement reliable stack trace To: Mark Brown , Mark Rutland References: <20201012172605.10715-1-broonie@kernel.org> <13095563-ff6d-b806-1bf3-efde4383456e@linux.microsoft.com> <20210128142250.GC4537@sirena.org.uk> <20210128152649.6zin3hzim3etbv2p@treble> <20210201160225.GD66060@C02TD0UTHF1T.local> <20210201162218.GD5960@sirena.org.uk> From: "Madhavan T. Venkataraman" Message-ID: <287ab2b9-0d04-d938-e858-3a2a03b3b1d5@linux.microsoft.com> Date: Mon, 1 Feb 2021 15:40:16 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20210201162218.GD5960@sirena.org.uk> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210201_164019_535393_34404FC9 X-CRM114-Status: GOOD ( 15.47 ) 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: Julien Thierry , Catalin Marinas , Josh Poimboeuf , Miroslav Benes , Will Deacon , linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 2/1/21 10:22 AM, Mark Brown wrote: > On Mon, Feb 01, 2021 at 04:02:25PM +0000, Mark Rutland wrote: >> On Mon, Feb 01, 2021 at 09:21:43AM -0600, Madhavan T. Venkataraman wrote: > >>> OK. Before this whole discussion, I did not know that the compiler cannot be trusted. > >> I think "the compiler cannot be trusted" is overly strong. We want to >> *verify* that the compiler is doing what we expect, which might be more >> than what it guarantees to do (and those expectations can change over >> time), but it doesn't mean we should try to avoid the compiler wherever >> possible. > > Right, part of what objtool offers here is that it is a static checker > which has an independent implementation of the assumptions we have about > the generated code to that in the compiler - the fact that we've got two > implementations means we're more likely to notice any implementation > drift or unintended changes that affect those assumptions. Moving code > generation into objtool would mean we were again relying on a single > implementation. > Agreed. And I am fine with the compiler doing it and objtool checking it. If we find that the compiler's implementation does not perform well enough for the kernel, we can revisit this point. Madhavan _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel