From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [216.205.24.124]) by sourceware.org (Postfix) with ESMTP id 9BE643854814 for ; Tue, 16 Mar 2021 14:39:17 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org 9BE643854814 Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-307-JIlCdklQNL-sAdQU4SQspA-1; Tue, 16 Mar 2021 10:39:12 -0400 X-MC-Unique: JIlCdklQNL-sAdQU4SQspA-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 523DE1015C8F; Tue, 16 Mar 2021 14:39:11 +0000 (UTC) Received: from oldenburg.str.redhat.com (ovpn-112-254.ams2.redhat.com [10.36.112.254]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 799F06091A; Tue, 16 Mar 2021 14:39:10 +0000 (UTC) From: Florian Weimer To: Adhemerval Zanella Cc: libc-alpha@sourceware.org Subject: Re: [PATCH 05/18] nptl: Remove longjmp, siglongjmp from libpthread References: <8796069624b7ecb1a21f713da7e49295af151e2c.1615569355.git.fweimer@redhat.com> Date: Tue, 16 Mar 2021 15:39:18 +0100 In-Reply-To: (Adhemerval Zanella's message of "Tue, 16 Mar 2021 11:13:55 -0300") Message-ID: <87pmzznox5.fsf@oldenburg.str.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.1 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain X-Spam-Status: No, score=-12.5 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, KAM_SHORT, RCVD_IN_DNSWL_LOW, RCVD_IN_MSPIKE_H3, RCVD_IN_MSPIKE_WL, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 16 Mar 2021 14:39:19 -0000 * Adhemerval Zanella: > On 12/03/2021 14:49, Florian Weimer via Libc-alpha wrote: >> The definitions in libc are sufficient, the forwarders are no longer >> needed. >> >> The symbols have been moved using scripts/move-symbol-to-libc.py. >> s390-linux-gnu and s390x-linux-gnu need a new version placeholder >> to keep the GLIBC_2.19 symbol version in libpthread. >> >> Tested on i386-linux-gnu, powerpc64le-linux-gnu, s390x-linux-gnu, >> x86_64-linux-gnu. Built with build-many-glibcs.py. > > Patch looks good, I was working on a similar one as well. The only > suggestion is to keep the x86 _Static_assert regarding the priv field > in struct pthread_unwind_buf has space to store shadow stack pointer. > > I have done it by adding a new x86 longjmp implementation: > > diff --git a/sysdeps/unix/sysv/linux/x86/longjmp.c b/sysdeps/unix/sysv/linux/x86/longjmp.c > new file mode 100644 > index 0000000000..104592fd48 > --- /dev/null > +++ b/sysdeps/unix/sysv/linux/x86/longjmp.c > @@ -0,0 +1,39 @@ > +/* __libc_siglongjmp for Linux/x86 > + Copyright (C) 2021 Free Software Foundation, Inc. > + This file is part of the GNU C Library. > + > + The GNU C Library is free software; you can redistribute it and/or > + modify it under the terms of the GNU Lesser General Public > + License as published by the Free Software Foundation; either > + version 2.1 of the License, or (at your option) any later version. > + > + The GNU C Library is distributed in the hope that it will be useful, > + but WITHOUT ANY WARRANTY; without even the implied warranty of > + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU > + Lesser General Public License for more details. > + > + You should have received a copy of the GNU Lesser General Public > + License along with the GNU C Library; if not, see > + . */ > + > +#include > + > +#include > +#include > + > +#ifdef __x86_64__ > +# define SHADOW_STACK_POINTER_SIZE 8 > +#else > +# define SHADOW_STACK_POINTER_SIZE 4 > +#endif > + > +/* Assert that the priv field in struct pthread_unwind_buf has space > + to store shadow stack pointer. */ > +_Static_assert ((offsetof (struct pthread_unwind_buf, priv) > + <= SHADOW_STACK_POINTER_OFFSET) > + && ((offsetof (struct pthread_unwind_buf, priv) > + + sizeof (((struct pthread_unwind_buf *) 0)->priv)) > + >= (SHADOW_STACK_POINTER_OFFSET > + + SHADOW_STACK_POINTER_SIZE)), > + "Shadow stack pointer is not within private storage " > + "of pthread_unwind_buf."); Thanks, I've merged this into the series. Florian