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=-5.8 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 4B40CC433DB for ; Fri, 5 Feb 2021 02:37:34 +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 D6BF364FA7 for ; Fri, 5 Feb 2021 02:37:33 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D6BF364FA7 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:References: To:From:Subject:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=zCP6uv3RnZYc1z2FPtnVHqsqrmsFWo3w0saridfKKMY=; b=ekURgypLuNdZe1MXl5QASp5fK pWGT0mtaTmAIPZyebsmil0Vc+fenUvbpOe4kiEbG9rDZI5yYoTrGX3KGPZg6lMqAV9Oot+31V/Ut7 IRFRA98pLjQ0RXPaRfBd5x6zV8UwChWSErcLNrD7XK8pB9hWlc8mdFy7oTpPvLgobmTvPMleEtMOo tsFoj/KKHiVy8IFG6/ZqldeLw2xC4WKy4l9JWlTtwvYQG/RZH7VrgRFmmATAfH+kmbUfq5OtVmW9z 1b69v0y2SjGTxtoNHMK8cfIo05ws4VidoJUUZaYxy6sBIg9xQp6JBQl0FKS518qzhedyi/OQxaA61 5Cr9391TQ==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1l7qye-0008TI-Cr; Fri, 05 Feb 2021 02:36:08 +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 1l7qyc-0008Sz-1M for linux-arm-kernel@lists.infradead.org; Fri, 05 Feb 2021 02:36:06 +0000 Received: from [192.168.254.32] (unknown [47.187.219.45]) by linux.microsoft.com (Postfix) with ESMTPSA id 999B02059BB2; Thu, 4 Feb 2021 18:36:02 -0800 (PST) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 999B02059BB2 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1612492563; bh=gM50gMvERA9tnGPUew3I4AkwDBPUnbncsOUFn7QdG9k=; h=Subject:From:To:Cc:References:Date:In-Reply-To:From; b=rmMLVtwLN+3oX5YoTh5NBB0fQ2DhssG11BkEHmDp87fVi6TuyTTytDb/5MhYPxBuQ s+0buvQ31USnGVbIDR8UUJj6eXyz/Zcw/VJcuUArQ5ZCeBxHZsiQ2QGXlzbNzu++yj ZfA6GfEG2kjxg6UACKXtBnpF5mglsghXXKaj6D/Y= Subject: Re: [RFC PATCH 0/3] arm64: Implement reliable stack trace From: "Madhavan T. Venkataraman" To: 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> <20210202100547.GA59049@C02TD0UTHF1T.local> <20210203165302.GO55896@C02TD0UTHF1T.local> Message-ID: Date: Thu, 4 Feb 2021 20:36:01 -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: Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210204_213606_261077_14F9FED0 X-CRM114-Status: GOOD ( 13.61 ) 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 , Mark Brown , 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 Hi Mark, Could you please answer the two questions below? You are the expert. Help me understand the exact problems. Even if the proposal is not considered, I want to understand what is wrong with it. On 2/3/21 1:03 PM, Madhavan T. Venkataraman wrote: > > > On 2/3/21 10:53 AM, Mark Rutland wrote: >> The epilog you propose is also unsound in the face of asynchronous >> exceptions, so I suspect you haven't thought as hard about this as you >> need to. >> > Can you elaborate? I understand that an exception can happen right in the middle of the prolog or epilog. What extra problem is caused by the changed prolog and epilog? > > >> Even if the compiler uses a different prologue/epilogue sequence, we >> still need to verify that the rest of the function does nothing to >> undermine that. >> The epilog corrects the frame pointer even if it is modified by the function. It also restores the stack pointer correctly even if the function does not. What else can go wrong? Thanks in advance for the info. Madhavan _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel