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=-1.0 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 2AC0BC169C4 for ; Tue, 29 Jan 2019 21:56:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F0D222082F for ; Tue, 29 Jan 2019 21:56:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729680AbfA2V4d (ORCPT ); Tue, 29 Jan 2019 16:56:33 -0500 Received: from relay1.mentorg.com ([192.94.38.131]:65068 "EHLO relay1.mentorg.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727339AbfA2V4d (ORCPT ); Tue, 29 Jan 2019 16:56:33 -0500 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 1gobMk-0000De-NV from joseph_myers@mentor.com ; Tue, 29 Jan 2019 13:56:22 -0800 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; Tue, 29 Jan 2019 21:56:19 +0000 Received: from jsm28 (helo=localhost) by digraph.polyomino.org.uk with local-esmtp (Exim 4.90_1) (envelope-from ) id 1gobMg-0006bP-RG; Tue, 29 Jan 2019 21:56:18 +0000 Date: Tue, 29 Jan 2019 21:56:18 +0000 From: Joseph Myers X-X-Sender: jsm28@digraph.polyomino.org.uk To: Mathieu Desnoyers CC: carlos , Florian Weimer , 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: [RFC PATCH glibc 1/4] glibc: Perform rseq(2) registration at C startup and thread creation (v6) In-Reply-To: <632671842.3079.1548781059601.JavaMail.zimbra@efficios.com> Message-ID: References: <20190121213530.23803-1-mathieu.desnoyers@efficios.com> <632671842.3079.1548781059601.JavaMail.zimbra@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-01.mgc.mentorg.com (139.181.222.1) 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 Tue, 29 Jan 2019, Mathieu Desnoyers wrote: > I recalled that aarch64 defines RSEQ_SIG to a different value which maps to > a valid trap instruction. So I plan to move the RSEQ_SIG define to per-arch > headers like this: > > sysdeps/unix/sysv/linux/aarch64/bits/rseq.h | 24 ++ > sysdeps/unix/sysv/linux/arm/bits/rseq.h | 24 ++ > sysdeps/unix/sysv/linux/bits/rseq.h | 23 ++ > sysdeps/unix/sysv/linux/mips/bits/rseq.h | 24 ++ > sysdeps/unix/sysv/linux/powerpc/bits/rseq.h | 24 ++ > sysdeps/unix/sysv/linux/s390/bits/rseq.h | 24 ++ > sysdeps/unix/sysv/linux/x86/bits/rseq.h | 24 ++ > > where "bits/rseq.h" contains a #error: > > # error "Architecture does not define RSEQ_SIG. > > sys/rseq.h will now include . We're trying to reduce the number of cases where most or all new glibc architecture ports need to provide a bits/ header, by making the generic headers handle the common case. So a generic header with a #error, and lots of architecture-specific headers mostly with the same value for RSEQ_SIG, seems unfortunate. I'd hope the generic header could use a generic value, with architecture-specific variants only for architectures with some reason for a different value. -- Joseph S. Myers joseph@codesourcery.com