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=-4.1 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 AE676C433E1 for ; Wed, 15 Jul 2020 14:54:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 84185206D5 for ; Wed, 15 Jul 2020 14:54:08 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=efficios.com header.i=@efficios.com header.b="c67AszQo" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726710AbgGOOyI (ORCPT ); Wed, 15 Jul 2020 10:54:08 -0400 Received: from mail.efficios.com ([167.114.26.124]:53588 "EHLO mail.efficios.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726670AbgGOOyH (ORCPT ); Wed, 15 Jul 2020 10:54:07 -0400 Received: from localhost (localhost [127.0.0.1]) by mail.efficios.com (Postfix) with ESMTP id 019F228288D; Wed, 15 Jul 2020 10:54:07 -0400 (EDT) Received: from mail.efficios.com ([127.0.0.1]) by localhost (mail03.efficios.com [127.0.0.1]) (amavisd-new, port 10032) with ESMTP id UI-Yt_BGGMDe; Wed, 15 Jul 2020 10:54:06 -0400 (EDT) Received: from localhost (localhost [127.0.0.1]) by mail.efficios.com (Postfix) with ESMTP id C501428262B; Wed, 15 Jul 2020 10:54:06 -0400 (EDT) DKIM-Filter: OpenDKIM Filter v2.10.3 mail.efficios.com C501428262B DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=efficios.com; s=default; t=1594824846; bh=54IAB4nGaEdAThpU9gOAvhwf7R9x5qsgZhVuNCgBOPQ=; h=Date:From:To:Message-ID:MIME-Version; b=c67AszQopibnIZZ5NgaobX0YPlXDxRsEZybal42YWvqES/aSF8tql5QXiPN0jzITO nza83eErrmii8q09TFMTqDQt4A1MS7ERNW/80Mw847nL+vBOekZi80j6uSUS03vsqP tQKtXo/Z6jCSXB0lEvLX/D/nGuFEGJHJGnF50lPBEdN2GcuH5w4pxhyCDgZGAbAWcj 3Yf5CDENNRAZmNXsUpZAxVINLO28Vd9RDfWw9SXHE/3MxNTZDhjqqhgAiqSMpB3uhz 11zdUroTH5uEsInbg0eyVQoJy7PtmipkXP7VNk7UvMUbSBvWN93FEaaFmj8hJR2Y+d f0Xnh2A/ZLxSA== X-Virus-Scanned: amavisd-new at efficios.com Received: from mail.efficios.com ([127.0.0.1]) by localhost (mail03.efficios.com [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id WerSgHc_o-Fa; Wed, 15 Jul 2020 10:54:06 -0400 (EDT) Received: from mail03.efficios.com (mail03.efficios.com [167.114.26.124]) by mail.efficios.com (Postfix) with ESMTP id B8B4D282626; Wed, 15 Jul 2020 10:54:06 -0400 (EDT) Date: Wed, 15 Jul 2020 10:54:06 -0400 (EDT) From: Mathieu Desnoyers To: Florian Weimer Cc: carlos , Peter Zijlstra , linux-kernel , Thomas Gleixner , paulmck , Boqun Feng , "H. Peter Anvin" , Paul Turner , linux-api , Christian Brauner Message-ID: <1481331967.14276.1594824846736.JavaMail.zimbra@efficios.com> In-Reply-To: <87mu4028uk.fsf@oldenburg2.str.redhat.com> References: <20200714030348.6214-1-mathieu.desnoyers@efficios.com> <87a7028d5u.fsf@oldenburg2.str.redhat.com> <2452161.11491.1594732791558.JavaMail.zimbra@efficios.com> <71f08b3a-56f5-0e0f-53b0-cc680f7e8181@redhat.com> <2053637148.14136.1594818777608.JavaMail.zimbra@efficios.com> <87y2nk29rp.fsf@oldenburg2.str.redhat.com> <882700738.14181.1594819884049.JavaMail.zimbra@efficios.com> <87mu4028uk.fsf@oldenburg2.str.redhat.com> Subject: Re: [RFC PATCH 2/4] rseq: Allow extending struct rseq MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-Originating-IP: [167.114.26.124] X-Mailer: Zimbra 8.8.15_GA_3955 (ZimbraWebClient - FF78 (Linux)/8.8.15_GA_3953) Thread-Topic: rseq: Allow extending struct rseq Thread-Index: GU+HWQn+q08bfey6uiSkHPIIjdE8lw== Sender: linux-api-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-api@vger.kernel.org ----- On Jul 15, 2020, at 9:42 AM, Florian Weimer fweimer@redhat.com wrote: > * Mathieu Desnoyers: > [...] >> How would this allow early-rseq-adopter libraries to interact with >> glibc ? > > Under all extension proposals I've seen so far, early adopters are > essentially incompatible with glibc rseq registration. I don't think > you can have it both ways. The basic question I'm not sure about is whether we are allowed to increase the size and alignement of __rseq_abi from e.g. glibc 2.32 to glibc 2.33. If not, then we just need to find another way to extend struct rseq, e.g. by adding a pointer to another extended structure in the padding space we have at the end of struct rseq. Thanks, Mathieu -- Mathieu Desnoyers EfficiOS Inc. http://www.efficios.com