On Tue, 5 Apr 2016, Mikulas Patocka wrote:
>
>
> On Tue, 5 Apr 2016, Helge Deller wrote:
>
> > On 05.04.2016 19:36, Mikulas Patocka wrote:
> > > On Tue, 5 Apr 2016, Mikulas Patocka wrote:
> > >
> > >> Hi
> > >>
> > >> 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)
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).
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.
Mikulas
/* this will crash pa-risc kernel if it is compiled with CONFIG_UNIX=m */
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
int main(void)
{
int s, r;
s = socket(PF_UNIX, SOCK_STREAM, 0);
if (s == -1) perror("socket"), exit(1);
r = ioctl(s, SIOCOUTQ, 0x124);
if (r == -1) perror("ioctl"), exit(1);
return 0;
}
Attachment:
exception.tar
Description: exception module
