From owner-freebsd-current@freebsd.org Tue Oct 31 09:28:30 2017 Return-Path: Delivered-To: freebsd-current@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 4AE88E53290 for ; Tue, 31 Oct 2017 09:28:30 +0000 (UTC) (envelope-from kostikbel@gmail.com) Received: from kib.kiev.ua (kib.kiev.ua [IPv6:2001:470:d5e7:1::1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id C3E516AF2D; Tue, 31 Oct 2017 09:28:29 +0000 (UTC) (envelope-from kostikbel@gmail.com) Received: from tom.home (kib@localhost [127.0.0.1]) by kib.kiev.ua (8.15.2/8.15.2) with ESMTPS id v9V9S36S027499 (version=TLSv1.2 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO); Tue, 31 Oct 2017 11:28:03 +0200 (EET) (envelope-from kostikbel@gmail.com) DKIM-Filter: OpenDKIM Filter v2.10.3 kib.kiev.ua v9V9S36S027499 Received: (from kostik@localhost) by tom.home (8.15.2/8.15.2/Submit) id v9V9S31V027498; Tue, 31 Oct 2017 11:28:03 +0200 (EET) (envelope-from kostikbel@gmail.com) X-Authentication-Warning: tom.home: kostik set sender to kostikbel@gmail.com using -f Date: Tue, 31 Oct 2017 11:28:03 +0200 From: Konstantin Belousov To: Andreas Tobler Cc: Tijl Coosemans , freebsd-current@FreeBSD.org, gerald@FreeBSD.org Subject: Re: Segfault in _Unwind_* code called from pthread_exit Message-ID: <20171031092803.GA2566@kib.kiev.ua> References: <20170824180830.199885b0@kalimero.tijl.coosemans.org> <20170825173851.09116ddc@kalimero.tijl.coosemans.org> <20170825234442.GO1700@kib.kiev.ua> <20170826202813.1240a1ef@kalimero.tijl.coosemans.org> <20170826184034.GR1700@kib.kiev.ua> <20171029182351.502f53cf@kalimero.tijl.coosemans.org> <20171029191358.GU2566@kib.kiev.ua> <9a724da4-70f1-4330-9a77-619739008a14@fgznet.ch> <20171030153207.15a42a1e@kalimero.tijl.coosemans.org> <9468430e-fda4-10f4-b6a0-aa40d7d64f5b@fgznet.ch> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <9468430e-fda4-10f4-b6a0-aa40d7d64f5b@fgznet.ch> User-Agent: Mutt/1.9.1 (2017-09-22) X-Spam-Status: No, score=-2.0 required=5.0 tests=ALL_TRUSTED,BAYES_00, DKIM_ADSP_CUSTOM_MED,FREEMAIL_FROM,NML_ADSP_CUSTOM_MED autolearn=no autolearn_force=no version=3.4.1 X-Spam-Checker-Version: SpamAssassin 3.4.1 (2015-04-28) on tom.home X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 31 Oct 2017 09:28:30 -0000 On Mon, Oct 30, 2017 at 10:54:05PM +0100, Andreas Tobler wrote: > On 30.10.17 15:32, Tijl Coosemans wrote: > > On Sun, 29 Oct 2017 20:40:46 +0100 Andreas Tobler wrote: > >> Attached what I have for libgcc. It can be applied to gcc5-8, should > >> give no issues. The mentioned tc from this thread and mine, > >> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82635 do pass. > >> > >> What do you think? > > > > Like I said before the return address can be anything. It could for > > instance point to some instruction in a random function and then the > > stack unwinder will think thread_start was called from that function. > > There's no check you can add to libgcc to distinguish that from a > > normal valid return address. > > > Maybe not, and most probably I do not understand what is happening. But > with my modification I survive the test case. > > If no objections from your or Konstantin's side come up I will commit it > to the gcc repo. It will not 'fix' the issue, but it will improve the > gcc behavior. I posted something similar when the discussion thread started. From the cursory look, your patch is better than mine. The only difference that makes me wonder is that I used #ifdef KERN_PROC_SIGTRAMP around the block because I believe gcc has more relaxed policy about supporting obsoleted OS versions.