From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paul Burton Subject: Re: Crash in -next due to 'MIPS: Move FP usage checks into protected_{save, restore}_fp_context' Date: Mon, 27 Jul 2015 13:02:14 -0700 Message-ID: <20150727200214.GH7289@NP-P-BURTON> References: <20150715160918.GA27653@roeck-us.net> <20150727150652.GA1756@roeck-us.net> <20150727172142.GE7289@NP-P-BURTON> <20150727174622.GA10708@roeck-us.net> <20150727180442.GG7289@NP-P-BURTON> <20150727194401.GC14674@roeck-us.net> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Return-path: Content-Disposition: inline In-Reply-To: <20150727194401.GC14674@roeck-us.net> Sender: linux-kernel-owner@vger.kernel.org To: Guenter Roeck , Ralf Baechle Cc: linux-next@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mips@linux-mips.org List-Id: linux-next.vger.kernel.org On Mon, Jul 27, 2015 at 12:44:01PM -0700, Guenter Roeck wrote: > On Mon, Jul 27, 2015 at 11:04:42AM -0700, Paul Burton wrote: > > On Mon, Jul 27, 2015 at 10:46:22AM -0700, Guenter Roeck wrote: > > > On Mon, Jul 27, 2015 at 10:21:42AM -0700, Paul Burton wrote: > > > > On Mon, Jul 27, 2015 at 08:06:52AM -0700, Guenter Roeck wrote: > > > > > On Wed, Jul 15, 2015 at 09:09:18AM -0700, Guenter Roeck wrote: > > > > > > Hi, > > > > > > > > > > > my qemu test for mipsel crashes with next-20150715 as follows. > > > > > > > > > > > ping ... problem is still seen as of next-20150727. > > > > > > > > Hi Guenter, > > > > > > > > Apologies for the delay. Could you share your affected kernel > > > > configuration & which userland you're running? > > > > > > > > I've just tested with a malta_defconfig kernel & a buildroot based > > > > initramfs without problems, and things are also fine on my physical > > > > MIPSr6 setups. If you have any directions with which I can reproduce > > > > this problem that would be great. > > > > > > > This is with qemu in little endian mode. Big endian works fine. > > > > Yup, I was using little endian in both cases. malta_defconfig is little > > endian - sadly use of the el suffix is pretty inconsistent... > > > > Hi Paul, > > some more data: > > I tried with mipsel64, using malta_defconfig from 4.2-rc4 as starting point. > Same failure. All releases from 3.2 up to 4.2-rc4 pass the test, linux-next > as of today fails. > > Here is the log: > > http://server.roeck-us.net:8010/builders/qemu-mipsel64-next/builds/0/steps/qemubuildcommand/logs/stdio > > I pushed the initramfs, configuration, and test script into rootfs/mipsel64 > of https://github.com/groeck/linux-build-test. Hi Guenter, I'm currently mailing out v2 of the series which should fix your problem. It was an issue where the kernel would check the FP context for whether a SIGFPE should be generated even in cases where FP had not been used by userland, and thus had not been initialised. My userland is hard float & thus makes use of the FPU early whilst I believe yours is soft float, which explains the difference in behaviour. I think the endian difference probably boils down to what garbage the initial FP context contained. Ralf: can you update the patches in -next please? Thanks, Paul