From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 62461 invoked by alias); 12 Jul 2018 08:10:15 -0000 Mailing-List: contact libc-alpha-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: libc-alpha-owner@sourceware.org Received: (qmail 62452 invoked by uid 89); 12 Jul 2018 08:10:14 -0000 Authentication-Results: sourceware.org; auth=none X-Spam-SWARE-Status: No, score=-2.6 required=5.0 tests=AWL,BAYES_00,RCVD_IN_DNSWL_NONE,SPF_HELO_PASS,SPF_PASS autolearn=ham version=3.3.2 spammy= X-HELO: EUR04-HE1-obe.outbound.protection.outlook.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=armh.onmicrosoft.com; s=selector1-arm-com; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=R/cdu7y6gxggSx3kCHifceUebfW9bb6/ps+xkHUH7D4=; b=kPAUqTPIq2V7cNT6hqZ0Uh9d8ddf9Ut2yzvX0Hn5jKPyaT7Uj/dxoXF1RF7qQmTXigwslEWQn7kiWWmpyhRPPuVvf+waN/8Ylb01FVu/VWmj3LuijJYxuBgiOIHIpNlqIU+JeYFnS2Ze/vU7yrPKf/DHmIFVPqL/MNPkvJJZDTQ= Cc: nd@arm.com, Carlos O'Donell , Heiko Carstens , Vasily Gorbik Subject: Re: Restartable Sequences system call merged into Linux To: Stefan Liebler , libc-alpha@sourceware.org References: <1084280721.10859.1528746558696.JavaMail.zimbra@efficios.com> <086b8e77-80e5-0908-0fdf-e4b19f087990@linux.ibm.com> From: Szabolcs Nagy Message-ID: <5431019d-02f4-6ac2-e2de-f4f38118ddc1@arm.com> Date: Thu, 12 Jul 2018 08:10:00 -0000 User-Agent: Mozilla/5.0 (X11; Linux aarch64; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 MIME-Version: 1.0 In-Reply-To: <086b8e77-80e5-0908-0fdf-e4b19f087990@linux.ibm.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Return-Path: szabolcs.nagy@arm.com Authentication-Results: spf=none (sender IP is ) smtp.mailfrom=Szabolcs.Nagy@arm.com; Received-SPF: None (protection.outlook.com: arm.com does not designate permitted sender hosts) X-SW-Source: 2018-07/txt/msg00305.txt.bz2 On 11/07/18 17:03, Stefan Liebler wrote: > On 06/11/2018 09:49 PM, Mathieu Desnoyers wrote: >> Hi! >> >> Good news! The restartable sequences (rseq) system call is now merged into the master >> branch of the Linux kernel within the 4.18 merge window: >> >> https://github.com/torvalds/linux/commit/d82991a8688ad128b46db1b42d5d84396487a508 >> >> It would be important to discuss how we should proceed to integrate the library part >> of rseq (see tools/testing/selftests/rseq/rseq*.{ch}) into glibc, or if it should >> live in a standalone project. >> >> It should be noted that there can be only one rseq TLS area registered per thread, >> which can then be used by many libraries and by the executable, so this is a >> process-wide (per-thread) resource that we need to manage carefully. >> >> Thoughts ? >> >> Thanks! >> >> Mathieu >> >> > The structs rseq_cs and rseq are aligned to 32 bytes. > Please have a look at the bug: > "Bug 23403 - Wrong alignment of TLS variables" > (https://sourceware.org/bugzilla/show_bug.cgi?id=23403). > > @Carlos or somebody else: > Should this be fixed in the upcoming glibc release? > i think s390 can implement a hack that increases the internal pthread_t alignment to 64 or similar. that effectively fixes 2.28 in practice (huge tls alignment should be rare).