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 715B6C433E1 for ; Sun, 23 Aug 2020 00:13:15 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id DFA0E206BE for ; Sun, 23 Aug 2020 00:13:13 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DFA0E206BE Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.crashing.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from bilbo.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 4BYwh74yyGzDqSd for ; Sun, 23 Aug 2020 10:13:11 +1000 (AEST) Authentication-Results: lists.ozlabs.org; spf=permerror (SPF Permanent Error: Unknown mechanism found: ip:192.40.192.88/32) smtp.mailfrom=kernel.crashing.org (client-ip=63.228.1.57; helo=gate.crashing.org; envelope-from=segher@kernel.crashing.org; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=kernel.crashing.org Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) by lists.ozlabs.org (Postfix) with ESMTP id 4BYwfR1s5vzDqL4 for ; Sun, 23 Aug 2020 10:11:40 +1000 (AEST) 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 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 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: wangle6@huawei.com, gregkh@linuxfoundation.org, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, paulus@samba.org, nixiaoming@huawei.com Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" 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