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 AC5E6C43470 for ; Thu, 1 Apr 2021 17:55:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 831396112E for ; Thu, 1 Apr 2021 17:55:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234744AbhDARzv (ORCPT ); Thu, 1 Apr 2021 13:55:51 -0400 Received: from linux.microsoft.com ([13.77.154.182]:33344 "EHLO linux.microsoft.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236438AbhDARoy (ORCPT ); Thu, 1 Apr 2021 13:44:54 -0400 Received: from [192.168.254.32] (unknown [47.187.194.202]) by linux.microsoft.com (Postfix) with ESMTPSA id 3ED6F20B5681; Thu, 1 Apr 2021 10:44:54 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 3ED6F20B5681 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1617299094; bh=tj4All66YvRaz0uEaJH4fLorSz5QIaGO2BKEoSy8t1w=; h=Subject:To:Cc:References:From:Date:In-Reply-To:From; b=QhRPhOZITHB+GM/lRF9u00GgTQ5EDonsgz6Kg4SxH+WEOc5fNboP2tmwARdYXXJo9 zGFgGKHXD5XCDkYIhrjFCJ3Z+oxP7JVCRXzVQfTXXjIOldg9jg17BHtcVjXceVUADx PqrfhF+YSd2z/gxIMMJk+Z4JUfNMBJZp0+BfufOE= Subject: Re: [RFC PATCH v1 1/4] arm64: Implement infrastructure for stack trace reliability checks To: Mark Brown Cc: mark.rutland@arm.com, 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: <77bd5edeea72d44533c769b1e8c0fea7a9d7eb3a> <20210330190955.13707-1-madvenka@linux.microsoft.com> <20210330190955.13707-2-madvenka@linux.microsoft.com> <20210401152741.GK4758@sirena.org.uk> From: "Madhavan T. Venkataraman" Message-ID: Date: Thu, 1 Apr 2021 12:44:53 -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: <20210401152741.GK4758@sirena.org.uk> Content-Type: text/plain; charset=windows-1252 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: live-patching@vger.kernel.org On 4/1/21 10:27 AM, Mark Brown wrote: > On Tue, Mar 30, 2021 at 02:09:52PM -0500, madvenka@linux.microsoft.com wrote: >> From: "Madhavan T. Venkataraman" >> >> Implement a check_reliability() function that will contain checks for the >> presence of various features and conditions that can render the stack trace >> unreliable. > > This looks good to me with one minor stylistic thing: > >> +/* >> + * Special functions where the stack trace is unreliable. >> + */ >> +static struct function_range special_functions[] = { >> + { 0, 0 } >> +}; > > Might be good to put a comment here saying that this is terminating the > list rather than detecting a NULL function pointer: > > { /* sentinel */ } > > is a common idiom for that. > > Given that it's a fixed array we could also... > >> + for (func = special_functions; func->start; func++) { >> + if (pc >= func->start && pc < func->end) > > ...do these as > > for (i = 0; i < ARRAY_SIZE(special_functions); i++) > > so you don't need something like that, though that gets awkward when you > have to write out special_functions[i].field a lot. > > So many different potential colours for the bikeshed! I will make the above changes. Thanks! Madhavan