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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 41246C31E44 for ; Fri, 14 Jun 2019 10:07:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1FB2D21773 for ; Fri, 14 Jun 2019 10:07:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727350AbfFNKHC (ORCPT ); Fri, 14 Jun 2019 06:07:02 -0400 Received: from mx1.redhat.com ([209.132.183.28]:36836 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727283AbfFNKHC (ORCPT ); Fri, 14 Jun 2019 06:07:02 -0400 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id D6AE37E421; Fri, 14 Jun 2019 10:06:56 +0000 (UTC) Received: from oldenburg2.str.redhat.com (dhcp-192-180.str.redhat.com [10.33.192.180]) by smtp.corp.redhat.com (Postfix) with ESMTPS id B9C841001DC8; Fri, 14 Jun 2019 10:06:46 +0000 (UTC) From: Florian Weimer To: Mathieu Desnoyers Cc: carlos , Joseph Myers , Szabolcs Nagy , libc-alpha , Thomas Gleixner , Ben Maurer , Peter Zijlstra , "Paul E. McKenney" , Boqun Feng , Will Deacon , Dave Watson , Paul Turner , Rich Felker , linux-kernel , linux-api Subject: Re: [PATCH 1/5] glibc: Perform rseq(2) registration at C startup and thread creation (v10) References: <20190503184219.19266-1-mathieu.desnoyers@efficios.com> <87muj2k4ov.fsf@oldenburg2.str.redhat.com> <1528929896.22217.1559326257155.JavaMail.zimbra@efficios.com> <87o93d4lqb.fsf@oldenburg2.str.redhat.com> <117220011.27079.1559663870037.JavaMail.zimbra@efficios.com> <87wohzorj0.fsf@oldenburg2.str.redhat.com> <914051741.43025.1560348011775.JavaMail.zimbra@efficios.com> <802638054.3032.1560506584705.JavaMail.zimbra@efficios.com> Date: Fri, 14 Jun 2019 12:06:45 +0200 In-Reply-To: <802638054.3032.1560506584705.JavaMail.zimbra@efficios.com> (Mathieu Desnoyers's message of "Fri, 14 Jun 2019 06:03:04 -0400 (EDT)") Message-ID: <87ftocwkei.fsf@oldenburg2.str.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.27]); Fri, 14 Jun 2019 10:07:02 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Mathieu Desnoyers: > ----- On Jun 12, 2019, at 4:00 PM, Mathieu Desnoyers mathieu.desnoyers@efficios.com wrote: > >> ----- On Jun 10, 2019, at 4:43 PM, carlos carlos@redhat.com wrote: >> >>> On 6/6/19 7:57 AM, Florian Weimer wrote: >>>> Let me ask the key question again: Does it matter if code observes the >>>> rseq area first without kernel support, and then with kernel support? >>>> If we don't expect any problems immediately, we do not need to worry >>>> much about the constructor ordering right now. I expect that over time, >>>> fixing this properly will become easier. >>> >>> I just wanted to chime in and say that splitting this into: >>> >>> * Ownership (__rseq_handled) >>> >>> * Initialization (__rseq_abi) >>> >>> Makes sense to me. >>> >>> I agree we need an answer to this question of ownership but not yet >>> initialized, to owned and initialized. >>> >>> I like the idea of having __rseq_handled in ld.so. >> >> Very good, so I'll implement this approach. Sorry for the delayed >> feedback, I am traveling this week. > > I had issues with cases where application or LD_PRELOAD library also > define the __rseq_handled symbol. They appear not to see the same > address as the one initialized by ld.so. What exactly did you do? How did you determine the addresses? How is __rseq_handled defined in ld.so? Thanks, Florian