From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 16292 invoked by alias); 26 Apr 2016 05:55:23 -0000 Mailing-List: contact binutils-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: binutils-owner@sourceware.org Received: (qmail 15616 invoked by uid 89); 26 Apr 2016 05:54:56 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-2.5 required=5.0 tests=AWL,BAYES_00,FREEMAIL_FROM,RCVD_IN_DNSWL_LOW,SPF_PASS autolearn=ham version=3.3.2 spammy=horrible, complication, pies X-HELO: mail-pa0-f52.google.com Received: from mail-pa0-f52.google.com (HELO mail-pa0-f52.google.com) (209.85.220.52) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with (AES128-GCM-SHA256 encrypted) ESMTPS; Tue, 26 Apr 2016 05:54:55 +0000 Received: by mail-pa0-f52.google.com with SMTP id bt5so2366188pac.3 for ; Mon, 25 Apr 2016 22:54:55 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=9h2wSLUnDz+nB1HH22I/fDYovDpWy9VBwRu9ho31QL8=; b=fX1VI/gExSa+iBw1qfLwuSCjdaGPOMMj44EchEXebSYiGyo6+NlY4qcXsdEXbnnegU 5HxGbt7gCwYI5C6ugEpiNpgfesnu2PcaEFHdKWRAVueGA6jf0bS0csyHQUuHN2478gPw Ue8ZdIiDnmXdsZ9pu6gVuk5gOWjBxQ1YZVzps6TJKL6IAjhoHLoxq7pLMHS9CPlgLEK/ ON0oTenyyrCUnGfC2tfrmhfolLS366dksbarCQPYsqkllE/abVjKobCvP+bn0AbooSL3 gW21gKPWWHb+L5fRB8FfItUOlzokw8L2kvCzfljx0qjwOqcGtiVvgX03WhPXiIteLhea wAQg== X-Gm-Message-State: AOPr4FWwMo7a4V0GN8wypB3BXh5yESCiXjyOVYFHPJd3Kx3e5Rb8XBnxF3kOp43yv8Ke2Q== X-Received: by 10.66.184.40 with SMTP id er8mr1032738pac.134.1461650093438; Mon, 25 Apr 2016 22:54:53 -0700 (PDT) Received: from bubble.grove.modra.org (CPE-58-160-146-233.sa.bigpond.net.au. [58.160.146.233]) by smtp.gmail.com with ESMTPSA id a5sm34595719pat.19.2016.04.25.22.54.51 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 25 Apr 2016 22:54:52 -0700 (PDT) Received: by bubble.grove.modra.org (Postfix, from userid 1000) id 1793CEA0157; Tue, 26 Apr 2016 15:24:48 +0930 (ACST) Date: Tue, 26 Apr 2016 05:55:00 -0000 From: Alan Modra To: Jeff Law Cc: Richard Biener , "H.J. Lu" , Cary Coutant , Joe Groff , Binutils , GCC Subject: Re: Preventing preemption of 'protected' symbols in GNU ld 2.26 [aka should we revert the fix for 65248] Message-ID: <20160426055447.GL27353@bubble.grove.modra.org> References: <56FB5061.9010303@redhat.com> <20160330143421.GM15812@bubble.grove.modra.org> <571161D0.10601@redhat.com> <20160418144911.GG15088@bubble.grove.modra.org> <20160419050805.GI15088@bubble.grove.modra.org> <08719312-4e17-21f9-7513-6ad4b92833fc@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <08719312-4e17-21f9-7513-6ad4b92833fc@redhat.com> User-Agent: Mutt/1.5.23 (2014-03-12) X-IsSubscribed: yes X-SW-Source: 2016-04/txt/msg00421.txt.bz2 On Mon, Apr 25, 2016 at 11:35:46AM -0600, Jeff Law wrote: > No, we revert to the gcc-4.9 behavior WRT protected visibility and ensure > that we're getting a proper diagnostic from the linker. > > That direction is consistent with the intent of protected visibility, fixes > the problem with preemption of protected symbols and gives us a diagnostic > for the case that can't be reasonably handled. I agree that this is the correct solution. Unfortunately there is a complication. PIE + shared lib using protected visibility worked fine with gcc-4.9, but since then code generated by gcc for PIEs on x86_64 has been optimized to rely on the horrible old hack of .dynbss and copy relocations. That means you'll have regressions from 4.9 if just reverting the protected visibility change.. The PIE optimization will need reverting too, and I imagine you'll see some resistance to that idea due to the fact that it delivers quite a nice performance improvement for PIEs. -- Alan Modra Australia Development Lab, IBM