From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.1 (2015-04-28) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: AS31976 209.132.180.0/23 X-Spam-Status: No, score=-4.0 required=3.0 tests=AWL,BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED, SPF_HELO_PASS,SPF_PASS shortcircuit=no autolearn=ham autolearn_force=no version=3.4.1 Received: from sourceware.org (server1.sourceware.org [209.132.180.131]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dcvr.yhbt.net (Postfix) with ESMTPS id 392A61F954 for ; Wed, 22 Aug 2018 10:08:50 +0000 (UTC) DomainKey-Signature: a=rsa-sha1; c=nofws; d=sourceware.org; h=list-id :list-unsubscribe:list-subscribe:list-archive:list-post :list-help:sender:date:from:to:cc:subject:message-id:references :mime-version:content-type:in-reply-to; q=dns; s=default; b=IIv6 KgtG/Noyi9x4V/8qxo8OuUntJ9byjGJ8CWGiW+C8Jp9XSL/ymxDjW6hWE2FDQHU3 N25ChmwlDYcKg+jZvXmq1tOeRgTJgZu6nSIVpmuwOsw7L5UN/DWeBvXbsPrmOw9/ 0HTepAol8iS1GMd/48+uATINXTnoVHI2nRKs0Wc= DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=sourceware.org; h=list-id :list-unsubscribe:list-subscribe:list-archive:list-post :list-help:sender:date:from:to:cc:subject:message-id:references :mime-version:content-type:in-reply-to; s=default; bh=16EpWiKGry zdNryhWykVBzpjiIE=; b=J9/1J6n7Wj2o6UgyV96X/Rd/Kpe3S/LO96vFgvSX9o w7z1EJSW6PWwK+DdSXc+IjPve+Skanue9SgDgjO4WZVq1PD9lLjr0McQO9uVUhMm tYMWX/DrL8VlyK8XflUunhYsSK0Oi+vjYtXlx7J8SNDAAdlidqMCrSgl4DVe/ZPY c= Received: (qmail 52777 invoked by alias); 22 Aug 2018 10:08:34 -0000 Mailing-List: contact libc-alpha-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: libc-alpha-owner@sourceware.org Received: (qmail 52739 invoked by uid 89); 22 Aug 2018 10:08:34 -0000 Authentication-Results: sourceware.org; auth=none X-HELO: gnu.wildebeest.org Date: Wed, 22 Aug 2018 12:08:29 +0200 From: Mark Wielaard To: Florian Weimer Cc: Cary Coutant , "H.J. Lu" , x86-64-abi , Binutils , GNU C Library Subject: Re: PT_NOTE alignment, NT_GNU_PROPERTY_TYPE_0, glibc and gold Message-ID: <20180822100829.GD11028@wildebeest.org> References: <480f513b-cfee-311a-0793-55eec81cd0fa@redhat.com> <3edfa10f-f5f0-bc31-5707-b15c78a84d0a@redhat.com> <20180816191628.GA8094@wildebeest.org> <20180817064146.GD8094@wildebeest.org> <20180817210524.GF8094@wildebeest.org> <101e7bf8-0270-5b53-61f0-6b852bb8666e@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <101e7bf8-0270-5b53-61f0-6b852bb8666e@redhat.com> User-Agent: Mutt/1.10.1 (2018-07-13) On Wed, Aug 22, 2018 at 11:39:02AM +0200, Florian Weimer wrote: > glibc 2.28 assumes that no 4-byte-aligned PT_NOTE segments contain GNU > property notes and will search for such notes in 8-byte aligned segments > only. The glibc changes were formally reviewed and checked for > interoperability with BFD ld. I think we have (had) community consensus for > them. I think there was actually consensus that they were a bad idea. There is a bug and a fix for BFD ld: https://sourceware.org/bugzilla/show_bug.cgi?id=22749 Unfortunately it didn't make it before the binutils release: https://sourceware.org/ml/binutils/2018-01/msg00354.html Which might have given the impression it wasn't a simple bug. Sorry about that. I have raised the issue a couple of time, but apparently not clearly enough. I think the best thing forward is to actually apply and backport the fix now (and fix cet.h) to generate proper GNU ELF notes. It is unfortunate there are a few binaries out there with these bad notes. But they haven't hit any long term distros yet. And they should impact only CET, which isnt really supported anywhere yet because there isn't any hardware for it. I understand the appeal of introducing a new section and segment type for storing these properties, but I fear that will be much more effort and coordination. Cheers, Mark