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=-17.4 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A,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 7954CC433DB for ; Fri, 12 Feb 2021 15:56:09 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (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 1D5AD64E70 for ; Fri, 12 Feb 2021 15:56:09 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1D5AD64E70 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=xen.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from list by lists.xenproject.org with outflank-mailman.84352.158182 (Exim 4.92) (envelope-from ) id 1lAanW-00038o-Ha; Fri, 12 Feb 2021 15:55:58 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 84352.158182; Fri, 12 Feb 2021 15:55:58 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lAanW-00038h-D8; Fri, 12 Feb 2021 15:55:58 +0000 Received: by outflank-mailman (input) for mailman id 84352; Fri, 12 Feb 2021 15:55:57 +0000 Received: from mail.xenproject.org ([104.130.215.37]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lAanV-00038a-IW for xen-devel@lists.xenproject.org; Fri, 12 Feb 2021 15:55:57 +0000 Received: from xenbits.xenproject.org ([104.239.192.120]) by mail.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lAanU-0000z3-C4; Fri, 12 Feb 2021 15:55:56 +0000 Received: from [54.239.6.186] (helo=a483e7b01a66.ant.amazon.com) by xenbits.xenproject.org with esmtpsa (TLS1.3:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.92) (envelope-from ) id 1lAanU-0004j9-61; Fri, 12 Feb 2021 15:55:56 +0000 X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=xen.org; s=20200302mail; h=Content-Transfer-Encoding:Content-Type:In-Reply-To: MIME-Version:Date:Message-ID:From:References:Cc:To:Subject; bh=QAwqRGeNVcQ/ggu7wEF3m0P68VKWsSn976OQ/azoyeI=; b=aEf1n+WhcJ3B1Pbrk+r+Jj7sDZ rVybiQauOZh0gZZe8k0r+Qa3lDDbGeZzUwDRQCxzi3UzcLvj1CK8tTE+5bOrjWt0cTe5D/qERVBfA G0GNzOltJYkzPc93VkX2ubuEnJh7DObMpzTAUHO/SNhcjAzwj2SCllPn31yppJ4S2m38=; Subject: Re: [PATCH 03/10] tools/libxg: Fix uninitialised variable in meminit() To: Andrew Cooper , Xen-devel Cc: Ian Jackson , Wei Liu , Stefano Stabellini References: <20210212153953.4582-1-andrew.cooper3@citrix.com> <20210212153953.4582-4-andrew.cooper3@citrix.com> From: Julien Grall Message-ID: <2437c26c-2bb6-ec43-37bd-3051b97eff56@xen.org> Date: Fri, 12 Feb 2021 15:55:54 +0000 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.7.1 MIME-Version: 1.0 In-Reply-To: <20210212153953.4582-4-andrew.cooper3@citrix.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 7bit Hi Andrew, On 12/02/2021 15:39, Andrew Cooper wrote: > Various version of gcc, when compiling with -Og, complain: > > xg_dom_arm.c: In function 'meminit': > xg_dom_arm.c:420:19: error: 'p2m_size' may be used uninitialized in this function [-Werror=maybe-uninitialized] > 420 | dom->p2m_size = p2m_size; > | ~~~~~~~~~~~~~~^~~~~~~~~~ > > Signed-off-by: Andrew Cooper This was reported nearly 3 years ago (see [1]) and it is pretty sad this was never merged :(. > --- > CC: Ian Jackson > CC: Wei Liu > CC: Stefano Stabellini > CC: Julien Grall > > Julien/Stefano: I can't work out how this variable is supposed to work, and > the fact that it isn't a straight accumulation across the RAM banks looks > suspect. It looks buggy, but the P2M is never used on Arm. In fact, you sent a patch a year ago to drop it (see [2]). It would be nice to revive it. > --- > tools/libs/guest/xg_dom_arm.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/tools/libs/guest/xg_dom_arm.c b/tools/libs/guest/xg_dom_arm.c > index 94948d2b20..f1b8d06f75 100644 > --- a/tools/libs/guest/xg_dom_arm.c > +++ b/tools/libs/guest/xg_dom_arm.c > @@ -373,7 +373,7 @@ static int meminit(struct xc_dom_image *dom) > const uint64_t modsize = dtb_size + ramdisk_size; > const uint64_t ram128mb = bankbase[0] + (128<<20); > > - xen_pfn_t p2m_size; > + xen_pfn_t p2m_size = 0; > uint64_t bank0end; > > assert(dom->rambase_pfn << XC_PAGE_SHIFT == bankbase[0]); > If your original series is too risky for 4.15, I would consider to remote p2m_size completely and always 0 dom->p2m_size. Cheers, [1] https://lore.kernel.org/xen-devel/20180314123203.30646-1-wei.liu2@citrix.com/ [2] https://patchwork.kernel.org/project/xen-devel/patch/20191217201550.15864-3-andrew.cooper3@citrix.com/ -- Julien Grall