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 F27593894C2A for ; Mon, 7 Jun 2021 18:13:28 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org F27593894C2A 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-248-U9yqHIXpOA-cedKZH154xg-1; Mon, 07 Jun 2021 14:13:27 -0400 X-MC-Unique: U9yqHIXpOA-cedKZH154xg-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id CE90A805EF9; Mon, 7 Jun 2021 18:13:25 +0000 (UTC) Received: from tucnak.zalov.cz (ovpn-112-147.ams2.redhat.com [10.36.112.147]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 1917560CC9; Mon, 7 Jun 2021 18:13:24 +0000 (UTC) Received: from tucnak.zalov.cz (localhost [127.0.0.1]) by tucnak.zalov.cz (8.16.1/8.16.1) with ESMTPS id 157IDM184107369 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NOT); Mon, 7 Jun 2021 20:13:23 +0200 Received: (from jakub@localhost) by tucnak.zalov.cz (8.16.1/8.16.1/Submit) id 157IDLN84107368; Mon, 7 Jun 2021 20:13:21 +0200 Date: Mon, 7 Jun 2021 20:13:21 +0200 From: Jakub Jelinek To: Jeff Law Cc: Andrew Pinski , Fangrui Song , Fangrui Song , GCC Patches , Jan Hubicka Subject: Re: [PATCH] Add --enable-default-semantic-interposition to GCC configure Message-ID: <20210607181321.GL7746@tucnak> Reply-To: Jakub Jelinek References: <20210606231215.49899-1-maskray@google.com> MIME-Version: 1.0 In-Reply-To: X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline X-Spam-Status: No, score=-5.8 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_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: gcc-patches@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gcc-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 07 Jun 2021 18:13:30 -0000 On Mon, Jun 07, 2021 at 12:01:55PM -0600, Jeff Law via Gcc-patches wrote: > > This breaks assumptions across the board. If software packages want > > to use -fno-semantic-interposition that is one thing. But distros > > should not be changing the default. This is just like using > > -ffast-math :). > Some distros already force immediate binding at link time for security > purposes on a distro-wide basis which, IIUC, does the same thing, but > without the benefits from a code generation standpoint. If you are talking about -Wl,-z,now, that is very different, semantic interposition then still works just fine. If you are talking about the glibc style by hand "protected" visibility, bind calls to symbols defined in the same library through internal symbols, then that is done only for a couple of packages and is stronger than -fno-semantic-interposition. Jakub