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_PASS,URIBL_BLOCKED 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 E1CE3C433F4 for ; Wed, 19 Sep 2018 19:49:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 938A720880 for ; Wed, 19 Sep 2018 19:49:19 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 938A720880 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=codesourcery.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732755AbeITB2n (ORCPT ); Wed, 19 Sep 2018 21:28:43 -0400 Received: from relay1.mentorg.com ([192.94.38.131]:37836 "EHLO relay1.mentorg.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727844AbeITB2n (ORCPT ); Wed, 19 Sep 2018 21:28:43 -0400 Received: from nat-ies.mentorg.com ([192.94.31.2] helo=svr-ies-mbx-01.mgc.mentorg.com) by relay1.mentorg.com with esmtps (TLSv1.2:ECDHE-RSA-AES256-SHA384:256) id 1g2iTG-0004lv-6L from joseph_myers@mentor.com ; Wed, 19 Sep 2018 12:49:10 -0700 Received: from digraph.polyomino.org.uk (137.202.0.90) by svr-ies-mbx-01.mgc.mentorg.com (139.181.222.1) with Microsoft SMTP Server (TLS) id 15.0.1320.4; Wed, 19 Sep 2018 20:49:06 +0100 Received: from jsm28 (helo=localhost) by digraph.polyomino.org.uk with local-esmtp (Exim 4.90_1) (envelope-from ) id 1g2iTC-0001VE-AK; Wed, 19 Sep 2018 19:49:06 +0000 Date: Wed, 19 Sep 2018 19:49:06 +0000 From: Joseph Myers X-X-Sender: jsm28@digraph.polyomino.org.uk To: Szabolcs Nagy CC: Mathieu Desnoyers , Carlos O'Donell , Florian Weimer , , Thomas Gleixner , Ben Maurer , Peter Zijlstra , "Paul E. McKenney" , Boqun Feng , Will Deacon , Dave Watson , Paul Turner , , , Subject: Re: [RFC PATCH] glibc: Perform rseq(2) registration at nptl init and thread creation In-Reply-To: Message-ID: References: <20180919144438.1066-1-mathieu.desnoyers@efficios.com> User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" X-Originating-IP: [137.202.0.90] X-ClientProxiedBy: SVR-IES-MBX-07.mgc.mentorg.com (139.181.222.7) To svr-ies-mbx-01.mgc.mentorg.com (139.181.222.1) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 19 Sep 2018, Szabolcs Nagy wrote: > i don't think there is precedent for exposing tls symbol in glibc > (e.g. errno is exposed via __errno_location function) so there > might be issues with this (but i don't have immediate concerns). There have been suggestions to expose TLS errno - but also suggestions that use of __errno_location is more efficient, at least in terms of code size everywhere errno is accessed (for some ABIs, anyway). The ABI tests have code that would list .tbss symbols as "T" in ABI test baselines, but no existing ABI baselines use that. -- Joseph S. Myers joseph@codesourcery.com From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joseph Myers Subject: Re: [RFC PATCH] glibc: Perform rseq(2) registration at nptl init and thread creation Date: Wed, 19 Sep 2018 19:49:06 +0000 Message-ID: References: <20180919144438.1066-1-mathieu.desnoyers@efficios.com> Mime-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: Szabolcs Nagy Cc: Mathieu Desnoyers , Carlos O'Donell , Florian Weimer , nd@arm.com, Thomas Gleixner , Ben Maurer , Peter Zijlstra , "Paul E. McKenney" , Boqun Feng , Will Deacon , Dave Watson , Paul Turner , libc-alpha@sourceware.org, linux-kernel@vger.kernel.org, linux-api@vger.kernel.org List-Id: linux-api@vger.kernel.org On Wed, 19 Sep 2018, Szabolcs Nagy wrote: > i don't think there is precedent for exposing tls symbol in glibc > (e.g. errno is exposed via __errno_location function) so there > might be issues with this (but i don't have immediate concerns). There have been suggestions to expose TLS errno - but also suggestions that use of __errno_location is more efficient, at least in terms of code size everywhere errno is accessed (for some ABIs, anyway). The ABI tests have code that would list .tbss symbols as "T" in ABI test baselines, but no existing ABI baselines use that. -- Joseph S. Myers joseph@codesourcery.com