From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0A215C433E1 for ; Sun, 23 Aug 2020 00:11:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E888D20825 for ; Sun, 23 Aug 2020 00:11:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728739AbgHWALy (ORCPT ); Sat, 22 Aug 2020 20:11:54 -0400 Received: from gate.crashing.org ([63.228.1.57]:49551 "EHLO gate.crashing.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728434AbgHWALy (ORCPT ); Sat, 22 Aug 2020 20:11:54 -0400 Received: from gate.crashing.org (localhost.localdomain [127.0.0.1]) by gate.crashing.org (8.14.1/8.14.1) with ESMTP id 07N0B38x017004; Sat, 22 Aug 2020 19:11:03 -0500 Received: (from segher@localhost) by gate.crashing.org (8.14.1/8.14.1/Submit) id 07N0B1Iw017003; Sat, 22 Aug 2020 19:11:01 -0500 X-Authentication-Warning: gate.crashing.org: segher set sender to segher@kernel.crashing.org using -f Date: Sat, 22 Aug 2020 19:11:01 -0500 From: Segher Boessenkool To: Guohua Zhong Cc: christophe.leroy@csgroup.eu, nixiaoming@huawei.com, wangle6@huawei.com, gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, paulus@samba.org, linuxppc-dev@lists.ozlabs.org Subject: Re: =?utf-8?B?UmXvvJpSZQ==?= =?utf-8?Q?=3A?= [PATCH] powerpc: Fix a bug in __div64_32 if divisor is zero Message-ID: <20200823001101.GO28786@gate.crashing.org> References: <8dedfcce-04e0-ec7d-6af5-ec1d6d8602b0@csgroup.eu> <20200822165433.58228-1-zhongguohua1@huawei.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200822165433.58228-1-zhongguohua1@huawei.com> User-Agent: Mutt/1.4.2.3i Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Aug 23, 2020 at 12:54:33AM +0800, Guohua Zhong wrote: > Yet, I have noticed that there is no checking of 'base' in these functions. > But I am not sure how to check is better.As we know that the result is > undefined when divisor is zero. It maybe good to print error and dump stack. > Let the process to know that the divisor is zero by sending SIGFPE. That is now what the PowerPC integer divide insns do: they just leave the result undefined (and they can set the overflow flag then, but no one uses that). Segher