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 [170.10.133.124]) by sourceware.org (Postfix) with ESMTP id D049A3858401 for ; Fri, 30 Jul 2021 07:57:15 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org D049A3858401 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-244-U8_mk9bIP6-0ziz_h5toaA-1; Fri, 30 Jul 2021 03:57:14 -0400 X-MC-Unique: U8_mk9bIP6-0ziz_h5toaA-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 4A7C3190D342; Fri, 30 Jul 2021 07:57:13 +0000 (UTC) Received: from oldenburg.str.redhat.com (unknown [10.39.192.123]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 787E560861; Fri, 30 Jul 2021 07:57:12 +0000 (UTC) From: Florian Weimer To: Fangrui Song via Libc-alpha Cc: Fangrui Song Subject: Re: [PATCH 0/3] Allow LLD 13.0.0 and improve compatibility with gold and clang References: <20210726035802.275992-1-maskray@google.com> Date: Fri, 30 Jul 2021 09:57:10 +0200 In-Reply-To: <20210726035802.275992-1-maskray@google.com> (Fangrui Song via Libc-alpha's message of "Sun, 25 Jul 2021 20:57:59 -0700") Message-ID: <87o8akz12h.fsf@oldenburg.str.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.2 (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; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, RCVD_IN_DNSWL_LOW, RCVD_IN_MSPIKE_H4, RCVD_IN_MSPIKE_WL, SPF_HELO_NONE, SPF_NONE, TXREP autolearn=ham autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) 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: Fri, 30 Jul 2021 07:57:16 -0000 * Fangrui Song via Libc-alpha: > For malloc/tst-compathooks-on, > > malloc/tst-compathooks-on: Symbol `__free_hook' has different size in= shared object, consider re-linking > > the root cause is that lld's symbol versioning is different from GNU ld i= n an unusal case: > > __asm__ (".symver " "__free_hook" "," "__free_hook" "@" "GLIBC_2.2.5"= ); > > This leaves two symbols __free_hook and __free_hook@GLIBC_2.2.5. > __free_hook is then attached a default version GLIBC_2.2.5. > I think malloc/malloc-debug.c uses a fragile versioned symbol here. > If the inline asm uses @@ the failure should go away. But we want to produce a compat symbol here. With the current version scripts, BFD ld will not export a symbol unless it is listed in the version script. That is, if I remove __free_hook from libc_malloc_debug in malloc/Versions, I get an ABI check failure: --- ../sysdeps/unix/sysv/linux/x86_64/64/libc_malloc_debug.abilist 202= 1-07-27 16:14:51.516781791 +0200 +++ =E2=80=A6/malloc/libc_malloc_debug.symlist 2021-07-30 09:55:09.8188754= 49 +0200 @@ -3 +2,0 @@ GLIBC_2.16 aligned_alloc F -GLIBC_2.2.5 __free_hook D 0x8 If this works with a linker, it appears to ignore =E2=80=9Clocal: *;=E2=80= =9D in version nodes for versioned symbols. That looks like a linker bug. Thanks, Florian