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=-4.0 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NORMAL_HTTP_TO_IP, NUMERIC_HTTP_ADDR,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1, WEIRD_PORT 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 91596C433C1 for ; Tue, 30 Mar 2021 12:35:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 672F0619B4 for ; Tue, 30 Mar 2021 12:35:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231584AbhC3MfD (ORCPT ); Tue, 30 Mar 2021 08:35:03 -0400 Received: from elvis.franken.de ([193.175.24.41]:37610 "EHLO elvis.franken.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230369AbhC3Meb (ORCPT ); Tue, 30 Mar 2021 08:34:31 -0400 Received: from uucp (helo=alpha) by elvis.franken.de with local-bsmtp (Exim 3.36 #1) id 1lRDZl-0003nX-00; Tue, 30 Mar 2021 14:34:29 +0200 Received: by alpha.franken.de (Postfix, from userid 1000) id 64DA4C1D90; Tue, 30 Mar 2021 14:24:37 +0200 (CEST) Date: Tue, 30 Mar 2021 14:24:37 +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: <20210330122437.GA10355@alpha.franken.de> References: <20210322015902.18451-1-yunqiang.su@cipunited.com> <20210329090058.GA6564@alpha.franken.de> 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 06:28:40PM +0800, YunQiang Su wrote: > Thomas Bogendoerfer 于2021年3月29日周一 下午5:30写道： > > > > 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 ? > > > > For rootfs, you can download > http://58.246.137.130:20180/debian-from/rootfs/buster-mipsel.tar.xz > or create by: > sudo debootstrap --arch mipsel --include golang-1.11-go \ > buster buster-mipsel http://deb.debian.org/debian > > For binary packages, you can download: > https://packages.debian.org/buster/mipsel/golang-1.11-go/download > > just chroot the rootfs and run: > /usr/lib/go-1.11/bin/go > It will crash if kernel's O32_FP64 option is enabled. now I'm confused. Do go binaries crash the kernel ? Or is this just the issue _not_ related to this patch ? I want a single go binary, which I can inspect about the FPXX thing and see how easy it would be to just patch the binary and make it run without this patch. Thomas. -- Crap can work. Given enough thrust pigs will fly, but it's not necessarily a good idea. [ RFC1925, 2.3 ]