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 586CFC433E5 for ; Mon, 29 Mar 2021 09:31:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 313DE61968 for ; Mon, 29 Mar 2021 09:31:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231948AbhC2Jap (ORCPT ); Mon, 29 Mar 2021 05:30:45 -0400 Received: from elvis.franken.de ([193.175.24.41]:33861 "EHLO elvis.franken.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231928AbhC2Ja1 (ORCPT ); Mon, 29 Mar 2021 05:30:27 -0400 Received: from uucp (helo=alpha) by elvis.franken.de with local-bsmtp (Exim 3.36 #1) id 1lQoE1-0003qb-00; Mon, 29 Mar 2021 11:30:21 +0200 Received: by alpha.franken.de (Postfix, from userid 1000) id 183E3C0AFD; Mon, 29 Mar 2021 11:00:58 +0200 (CEST) Date: Mon, 29 Mar 2021 11:00:58 +0200 From: Thomas Bogendoerfer To: YunQiang Su Cc: YunQiang Su , linux-mips , "Maciej W. Rozycki" , Jiaxun Yang , Philippe =?iso-8859-1?Q?Mathieu-Daud=E9?= , stable@vger.kernel.org Subject: Re: [PATCH v9] MIPS: force use FR=0 for FPXX binaries Message-ID: <20210329090058.GA6564@alpha.franken.de> References: <20210322015902.18451-1-yunqiang.su@cipunited.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On Mon, Mar 29, 2021 at 01:09:18PM +0800, YunQiang Su wrote: > YunQiang Su 于2021年3月22日周一 上午10:00写道： > > > > The MIPS FPU may have 3 mode: > > FR=0: MIPS I style, all of the FPR are single. > > FR=1: all 32 FPR can be double. > > FRE: redirecting the rw of odd-FPR to the upper 32bit of even-double FPR. > > > > The binary may have 3 mode: > > FP32: can only work with FR=0 and FRE mode > > FPXX: can work with all of FR=0/FR=1/FRE mode. > > FP64: can only work with FR=1 mode > > > > Some binary, for example the output of golang, may be mark as FPXX, > > while in fact they are FP32. It is caused by the bug of design and linker: > > Object produced by pure Go has no FP annotation while in fact they are FP32; > > if we link them with the C module which marked as FPXX, > > the result will be marked as FPXX. If these fake-FPXX binaries is executed > > in FR=1 mode, some problem will happen. > > > > In Golang, now we add the FP32 annotation, so the future golang programs > > won't have this problem. While for the existing binaries, we need a > > kernel workaround. > > > > We meet a new problem in Debian: with the O32_FP64 enabled kernel, > mips64el may also be affected. > https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=983583 hmm, raising this issue in this context before knowing more details, feels very trigger happy to me and this doesn't help accepting anything, jfyi... Could you please provide a link for downloading a golang binary, which would need this patch to run ? Thomas. -- Crap can work. Given enough thrust pigs will fly, but it's not necessarily a good idea. [ RFC1925, 2.3 ]