From mboxrd@z Thu Jan 1 00:00:00 1970 From: Helge Deller Subject: Re: kernel 4.6-rc unbootable due to module changes Date: Wed, 6 Apr 2016 23:44:18 +0200 Message-ID: <57058332.8050204@gmx.de> References: <570409DA.1060508@gmx.de> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Cc: linux-parisc@vger.kernel.org To: Mikulas Patocka , John David Anglin Return-path: In-Reply-To: List-ID: List-Id: linux-parisc.vger.kernel.org On 06.04.2016 16:30, Mikulas Patocka wrote: >>>>> The patch "parisc: Use generic extable search and sort routines" makes the >>>>> kernel unable to load any modules. It fails with: >>>>> >>>>> module unix: Unknown relocation: 9 >>>>> modprobe: FATAL: Error inserting unix (/lib/modules/4.6.0-rc2/kernel/net/unix/unix.ko): Invalid module format >>>>> >>>>> When I revert the patch, the kernel 4.6-rc2 boots fine. >>>>> >>>>> Apparently, the function apply_relocate_add in arch/parisc/kernel/module.c >>>>> doesn't handle the new relocation type. >>>>> >>>>> Mikulas >>>> >>>> BTW. I'm using hppa64 binutils 2.21 to build the kernel. It generates the >>>> R_PARISC_PCREL32 relocation that the kernel module loader doesn't handle: >>> >>> Can you try attached patch (untested) ? >>> >>> Helge >> >> I tried a similar patch, the system booted fine ... but then I discovered >> that the system boots fine no matter what value is written to *loc. >> >> Apparently, none of the modules trigger any exceptions in my >> configuration. >> >> I'll have to create a test module that triggers some exception. >> >> Mikulas > > Hmm - it's even more strange. > > I created a test kernel module that triggers an exception by using > get_user with an invalid address (see the attached file exception.tar) I see there is a kernel module /lib/test_user_copy.c as well. It seems to crash too. > On x86-64 the module loads fine, but on pa-risc it always crashes, even > with older kernel version (I tried versions 2.6.39, 4.5 and 4.6-rc2 and I > always get a crash). I don't fully trust the 4.5 kernel yet. I was working the last few days on trying to fix the FTRACE functions, but am seeing strange crashes too. Any chance that you can try 4.4-stable, just to make sure ? > When I write a userspace code that triggers a fault in module unix.ko, by > passing an invalid address to the ioctl syscall, the kernel also crashes. > > So, it seems that handling exceptions from modules never worked on > pa-risc, it was just masked by the fact that exceptions from modules don't > happen during normal use. I'll try to dig deeper as soon as I find time. Helge