From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752212AbdLFWAi (ORCPT ); Wed, 6 Dec 2017 17:00:38 -0500 Received: from smtprelay.synopsys.com ([198.182.60.111]:45043 "EHLO smtprelay.synopsys.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751598AbdLFWAg (ORCPT ); Wed, 6 Dec 2017 17:00:36 -0500 Subject: Re: [PATCH] frv: fix build failure To: Sudip Mukherjee , Geert Uytterhoeven , Vineet Gupta CC: Alexey Brodkin , "linux-kernel@vger.kernel.org" , "akpm@linux-foundation.org" , "linux-snps-arc@lists.infradead.org" , "linux-arch@vger.kernel.org" , Arnd Bergmann Newsgroups: gmane.linux.kernel.cross-arch,gmane.linux.kernel,gmane.linux.kernel.arc References: <1511302233-5008-1-git-send-email-sudipm.mukherjee@gmail.com> <1511457437.32422.6.camel@synopsys.com> <3a6fe86e-7a66-56df-3b1d-e2e8cd3e6eae@synopsys.com> <20171203223226.GA3741@sudip-laptop> From: Vineet Gupta Message-ID: <817df34a-f471-99d7-aaa1-94e0ee9d5ffa@synopsys.com> Date: Wed, 6 Dec 2017 14:00:23 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.5.0 MIME-Version: 1.0 In-Reply-To: <20171203223226.GA3741@sudip-laptop> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.10.161.67] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/03/2017 02:32 PM, Sudip Mukherjee wrote: > On Mon, Nov 27, 2017 at 10:25:16AM -0800, Vineet Gupta wrote: >> +CC linux-arch, Arnd >> >> On 11/23/2017 09:17 AM, Alexey Brodkin wrote: >>> Hi Sudip, >>> >>> On Tue, 2017-11-21 at 22:10 +0000, Sudip Mukherjee wrote: > > > >> I understand the case/need for adding a weak/common abort() as a >> quick fix for handling such cases, but perhaps we should not and >> instead fix the rootcause. In this specific case, Claudiu mentioned >> that gcc was generating abort due to something like this (flagging a >> possible divide by zero due to >> -fno-isolate-erroneous-paths-dereference. >> >> a; >> >> fn1() { >> switch (a) >> case 0: >> return 1 / a; >> } >> >> Sudeep can you confirm that removing this hacking FRV build to not >> have this toggle fixes the abort issue. >> >> So the offending code needs to be fixed as in the end when that code >> path is taken system is hosed. > > The above case that you mentioned is indeed the case here. > mpihelp_divrem() in lib/mpi/mpih-div.c has this same divide by zero case. > > So, what should be the actual fix here? To remove the divide by zero. Or atleast have a __weak abort() defined in common code so all arches benefit from it ! -Vineet