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=-14.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1,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 112ADC433DB for ; Tue, 23 Mar 2021 12:41:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C41CB619BA for ; Tue, 23 Mar 2021 12:41:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231289AbhCWMlK (ORCPT ); Tue, 23 Mar 2021 08:41:10 -0400 Received: from linux.microsoft.com ([13.77.154.182]:51466 "EHLO linux.microsoft.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231305AbhCWMkx (ORCPT ); Tue, 23 Mar 2021 08:40:53 -0400 Received: from [192.168.254.32] (unknown [47.187.194.202]) by linux.microsoft.com (Postfix) with ESMTPSA id 4C00420B5680; Tue, 23 Mar 2021 05:40:50 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 4C00420B5680 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1616503250; bh=fyO5OQ1MPXrJo3wHhJyQvWPjoGtn/RSEVDvabSJsv1k=; h=Subject:To:Cc:References:From:Date:In-Reply-To:From; b=eiXkMmyle2ssvKgeEoUiPU29JsoyuIylPUXLLhxvpY3DsrgqhiH49PZPnjyEGHbtt suPb+C2C9SInJGPRNnxQYiliZnWzcazkH3c+xb8Bud67JLzr6z7DnIh3rLFjFLJruy KPPCyciXJhEjcj9KMlIHIsuyIcgzUlTYZrmUj2Kw= Subject: Re: [RFC PATCH v2 3/8] arm64: Terminate the stack trace at TASK_FRAME and EL0_FRAME To: Mark Rutland Cc: Mark Brown , jpoimboe@redhat.com, jthierry@redhat.com, catalin.marinas@arm.com, will@kernel.org, linux-arm-kernel@lists.infradead.org, live-patching@vger.kernel.org, linux-kernel@vger.kernel.org References: <5997dfe8d261a3a543667b83c902883c1e4bd270> <20210315165800.5948-1-madvenka@linux.microsoft.com> <20210315165800.5948-4-madvenka@linux.microsoft.com> <20210318182607.GO5469@sirena.org.uk> <20210323103644.GC95840@C02TD0UTHF1T.local> From: "Madhavan T. Venkataraman" Message-ID: <0f36fe36-c435-f12a-661b-7075f899e4fb@linux.microsoft.com> Date: Tue, 23 Mar 2021 07:40:49 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.7.1 MIME-Version: 1.0 In-Reply-To: <20210323103644.GC95840@C02TD0UTHF1T.local> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 3/23/21 5:36 AM, Mark Rutland wrote: > On Thu, Mar 18, 2021 at 03:29:19PM -0500, Madhavan T. Venkataraman wrote: >> >> >> On 3/18/21 1:26 PM, Mark Brown wrote: >>> On Mon, Mar 15, 2021 at 11:57:55AM -0500, madvenka@linux.microsoft.com wrote: >>> >>>> + /* Terminal record, nothing to unwind */ >>>> + if (fp == (unsigned long) regs->stackframe) { >>>> + if (regs->frame_type == TASK_FRAME || >>>> + regs->frame_type == EL0_FRAME) >>>> + return -ENOENT; >>>> return -EINVAL; >>>> + } >>> >>> This is conflating the reliable stacktrace checks (which your series >>> will later flag up with frame->reliable) with verifying that we found >>> the bottom of the stack by looking for this terminal stack frame record. >>> For the purposes of determining if the unwinder got to the bottom of the >>> stack we don't care what stack type we're looking at, we just care if it >>> managed to walk to this defined final record. >>> >>> At the minute nothing except reliable stack trace has any intention of >>> checking the specific return code but it's clearer to be consistent. >>> >> >> So, you are saying that the type check is redundant. OK. I will remove it >> and just return -ENOENT on reaching the final record. > > Yes please; and please fold that into the same patch that adds the final > records. > Will do. Thanks. Madhavan