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,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by aws-us-west-2-korg-lkml-1.web.codeaurora.org (Postfix) with ESMTP id 75345C004E4 for ; Mon, 11 Jun 2018 20:04:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F29FA20839 for ; Mon, 11 Jun 2018 20:04:40 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=efficios.com header.i=@efficios.com header.b="O1C2p8oi" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org F29FA20839 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=efficios.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 S933604AbeFKUEi (ORCPT ); Mon, 11 Jun 2018 16:04:38 -0400 Received: from mail.efficios.com ([167.114.142.138]:49166 "EHLO mail.efficios.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932139AbeFKUEf (ORCPT ); Mon, 11 Jun 2018 16:04:35 -0400 Received: from localhost (ip6-localhost [IPv6:::1]) by mail.efficios.com (Postfix) with ESMTP id 84B3D1BCA1E; Mon, 11 Jun 2018 16:04:34 -0400 (EDT) Received: from mail.efficios.com ([IPv6:::1]) by localhost (mail02.efficios.com [IPv6:::1]) (amavisd-new, port 10032) with ESMTP id bj48XmxqSzyl; Mon, 11 Jun 2018 16:04:34 -0400 (EDT) Received: from localhost (ip6-localhost [IPv6:::1]) by mail.efficios.com (Postfix) with ESMTP id 07DF11BCA1B; Mon, 11 Jun 2018 16:04:34 -0400 (EDT) DKIM-Filter: OpenDKIM Filter v2.10.3 mail.efficios.com 07DF11BCA1B DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=efficios.com; s=default; t=1528747474; bh=ILK2XKVdRd6EjsYTUwT5pnIka5COcALqHFTsCN1LG6s=; h=Date:From:To:Message-ID:MIME-Version; b=O1C2p8oiGDHzOkfczH2ELHLr4BoJHQM18czFhKNiyK7K2zuCZZqWxjjmJGFpo4EFd sHwgnM/IeHir0QHUHaSznzx15BWJGqogsxilyEpRBFiqxVa/UoTXMuAWFMUjYIHhBu n4VS5WE4WV0vzhXLlkvhE7ENk3yDqKlBKLKia4pAy0Kg7Cnvp/wKbz08+kQqPfnnIc wUq40fxzWIfnzRRfQArkwn82KI6t0ZQw6p1frmy9AqPgh4nlChsTRXKezihovE6Wg4 IJks0Np3MoYIXHwRtzOmS/Z8rjMSV84ShT09pDimc3lQKI33YUQ+fG3rG5o+eNGM3b SCTjl3uTupu2w== 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 DuMJsdJj0jce; Mon, 11 Jun 2018 16:04:33 -0400 (EDT) Received: from mail02.efficios.com (mail02.efficios.com [167.114.142.138]) by mail.efficios.com (Postfix) with ESMTP id E47C31BCA12; Mon, 11 Jun 2018 16:04:33 -0400 (EDT) Date: Mon, 11 Jun 2018 16:04:33 -0400 (EDT) From: Mathieu Desnoyers To: Florian Weimer Cc: Carlos O'Donell , Peter Zijlstra , "Paul E. McKenney" , Boqun Feng , Thomas Gleixner , linux-kernel , libc-alpha Message-ID: <305409897.10888.1528747473727.JavaMail.zimbra@efficios.com> In-Reply-To: <31fc101a-295b-067b-1a82-7e9e509fc92f@redhat.com> References: <1084280721.10859.1528746558696.JavaMail.zimbra@efficios.com> <31fc101a-295b-067b-1a82-7e9e509fc92f@redhat.com> Subject: Re: Restartable Sequences system call merged into Linux 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 8.8.8_GA_2096 (ZimbraWebClient - FF52 (Linux)/8.8.8_GA_1703) Thread-Topic: Restartable Sequences system call merged into Linux Thread-Index: zhJcsiSjFFTw3hSbC6qfc+ihAyNZFQ== Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org ----- On Jun 11, 2018, at 3:55 PM, Florian Weimer fweimer@redhat.com wrote: > On 06/11/2018 09:49 PM, Mathieu Desnoyers wrote: >> 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. > > Is it possible to resize the area after thread creation, perhaps even > from other threads? I'm not sure why we would want to resize it. The per-thread area is fixed-size. Its layout is here: include/uapi/linux/rseq.h: struct rseq The ABI is designed so that all users (program and libraries) can interact through this per-thread TLS area. > > If there is only one contiguous area, this generally means there needs > to be linker support, similar to what we have for initial-exec TLS today. Not entirely sure what you imply by "one contiguous area". All we need is a single fixed-size TLS area for each thread. Thanks, Mathieu > > Thanks, > Florian -- Mathieu Desnoyers EfficiOS Inc. http://www.efficios.com