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=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,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 A2847C31E44 for ; Fri, 14 Jun 2019 10:03:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4E0D821773 for ; Fri, 14 Jun 2019 10:03:09 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=efficios.com header.i=@efficios.com header.b="fvSF4UnS" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727561AbfFNKDH (ORCPT ); Fri, 14 Jun 2019 06:03:07 -0400 Received: from mail.efficios.com ([167.114.142.138]:33086 "EHLO mail.efficios.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727197AbfFNKDH (ORCPT ); Fri, 14 Jun 2019 06:03:07 -0400 Received: from localhost (ip6-localhost [IPv6:::1]) by mail.efficios.com (Postfix) with ESMTP id B2F3A251338; Fri, 14 Jun 2019 06:03:05 -0400 (EDT) Received: from mail.efficios.com ([IPv6:::1]) by localhost (mail02.efficios.com [IPv6:::1]) (amavisd-new, port 10032) with ESMTP id aGDopCXhabIV; Fri, 14 Jun 2019 06:03:05 -0400 (EDT) Received: from localhost (ip6-localhost [IPv6:::1]) by mail.efficios.com (Postfix) with ESMTP id 455F4251331; Fri, 14 Jun 2019 06:03:05 -0400 (EDT) DKIM-Filter: OpenDKIM Filter v2.10.3 mail.efficios.com 455F4251331 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=efficios.com; s=default; t=1560506585; bh=Hu2sfywP1wr/V2iml0Iwu3DskdZlle9a1sk8RIwPbAc=; h=Date:From:To:Message-ID:MIME-Version; b=fvSF4UnSVmbjIlv9Khoar4edqsd+o8saf61h4OK1+vIa0MgvAEnu/UKIG6N0a3apx tiA7uuHAHRZy4dE8/w6aFGS05JUYkzKpfU/Hp0sUR8dLGa1RTyvIoc1RcI+Zqs8uww EhYjeSssh2WOJo4xfeApdEIr7FfjxCje1SFA8lyywbM541+2WbLuP8fp/9665+tgwf upU2nGhuAZzX4ZgGUyxKMvD1Gy32eTP5WwAiGaTvDqWB9L8AurGI/iNK96XYEqjGr8 x870WRvXafGceB05ZQ0JHYiemFDLtNq8m2mtALm2Yrm9zKcaFGc6IoKaFgaHfxL6kx dzXk3iMwytTeQ== X-Virus-Scanned: amavisd-new at efficios.com Received: from mail.efficios.com ([IPv6:::1]) by localhost (mail02.efficios.com [IPv6:::1]) (amavisd-new, port 10026) with ESMTP id LKwutttasM3j; Fri, 14 Jun 2019 06:03:05 -0400 (EDT) Received: from mail02.efficios.com (mail02.efficios.com [167.114.142.138]) by mail.efficios.com (Postfix) with ESMTP id 1BD4A251327; Fri, 14 Jun 2019 06:03:05 -0400 (EDT) Date: Fri, 14 Jun 2019 06:03:04 -0400 (EDT) From: Mathieu Desnoyers To: carlos , Florian Weimer Cc: 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 Message-ID: <802638054.3032.1560506584705.JavaMail.zimbra@efficios.com> In-Reply-To: <914051741.43025.1560348011775.JavaMail.zimbra@efficios.com> 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> Subject: Re: [PATCH 1/5] glibc: Perform rseq(2) registration at C startup and thread creation (v10) MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-Originating-IP: [167.114.142.138] X-Mailer: Zimbra 8.8.12_GA_3803 (ZimbraWebClient - FF67 (Linux)/8.8.12_GA_3794) Thread-Topic: glibc: Perform rseq(2) registration at C startup and thread creation (v10) Thread-Index: 6rG93gdkMSoHS5ZP168diTIrRPG9C+LZilEL Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org ----- 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. I tried using the GL() macro in ld.so to set __rseq_handled, but it's the wrong address compared to what the preload lib and application observe. Any thoughts on how to solve this ? Thanks, Mathieu -- Mathieu Desnoyers EfficiOS Inc. http://www.efficios.com