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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 6EA88CDB47E for ; Wed, 18 Oct 2023 15:24:20 +0000 (UTC) Received: from list by lists.xenproject.org with outflank-mailman.618681.962651 (Exim 4.92) (envelope-from ) id 1qt8P3-00048l-Ea; Wed, 18 Oct 2023 15:24:09 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 618681.962651; Wed, 18 Oct 2023 15:24:09 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1qt8P3-00048e-Bd; Wed, 18 Oct 2023 15:24:09 +0000 Received: by outflank-mailman (input) for mailman id 618681; Wed, 18 Oct 2023 15:24:08 +0000 Received: from se1-gles-sth1-in.inumbo.com ([159.253.27.254] helo=se1-gles-sth1.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1qt8P2-000474-3y for xen-devel@lists.xenproject.org; Wed, 18 Oct 2023 15:24:08 +0000 Received: from support.bugseng.com (mail.bugseng.com [162.55.131.47]) by se1-gles-sth1.inumbo.com (Halon) with ESMTPS id 60a53383-6dca-11ee-98d4-6d05b1d4d9a1; Wed, 18 Oct 2023 17:24:07 +0200 (CEST) Received: from support.bugseng.com (support.bugseng.com [162.55.131.47]) by support.bugseng.com (Postfix) with ESMTPA id 716CE4EE0739; Wed, 18 Oct 2023 17:24:06 +0200 (CEST) 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" X-Inumbo-ID: 60a53383-6dca-11ee-98d4-6d05b1d4d9a1 MIME-Version: 1.0 Date: Wed, 18 Oct 2023 17:24:06 +0200 From: Nicola Vetrini To: Jan Beulich Cc: sstabellini@kernel.org, michal.orzel@amd.com, xenia.ragiadakou@amd.com, ayan.kumar.halder@amd.com, consulting@bugseng.com, andrew.cooper3@citrix.com, roger.pau@citrix.com, Wei Liu , xen-devel@lists.xenproject.org Subject: Re: [XEN PATCH v2 2/7] x86: add deviations for variables only used in asm code In-Reply-To: <4b96ba28-f2c9-68b5-7c7f-f4ca946022a4@suse.com> References: <5131b75996d0b91d4a98466f11dd927be910d7e5.1696833629.git.nicola.vetrini@bugseng.com> <4b96ba28-f2c9-68b5-7c7f-f4ca946022a4@suse.com> User-Agent: Roundcube Webmail/1.4.3 Message-ID: <8fd7b43f886d4728a4220ef35abd3423@bugseng.com> X-Sender: nicola.vetrini@bugseng.com Organization: BUGSENG s.r.l. Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit On 18/10/2023 16:56, Jan Beulich wrote: > On 18.10.2023 16:28, Nicola Vetrini wrote: >> On 16/10/2023 16:58, Jan Beulich wrote: >>> On 09.10.2023 08:54, Nicola Vetrini wrote: >>>> These variables are only used by asm code, and therefore >>>> the lack of a declaration is justified by the corresponding >>>> deviation comment. >>> >>> Hmm, you say "declaration" here, but according to my understanding >>> ... >>> >>>> --- a/xen/arch/x86/include/asm/asm_defns.h >>>> +++ b/xen/arch/x86/include/asm/asm_defns.h >>>> @@ -31,6 +31,7 @@ asm ( "\t.equ CONFIG_INDIRECT_THUNK, " >>>> * gets set up by the containing function. >>>> */ >>>> #ifdef CONFIG_FRAME_POINTER >>>> +/* SAF-1-safe */ >>>> register unsigned long current_stack_pointer asm("rsp"); >>> >>> ... this is a declaration, not a definition. >>> >> >> It has automatic storage duration and it's not defined afterwards > > Mind me asking what makes you derive "automatic storage duration"? > I also don't see how "not defined afterwards" matters here. This is > a special construct, not covered by the C standard. > > Jan Oh, you're right. I was fooled by the fact that this is not a standard construct. I see your point now. Thanks, -- Nicola Vetrini, BSc Software Engineer, BUGSENG srl (https://bugseng.com)