lkml.org 
[lkml]   [2023]   [Jan]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [PATCH v9] livepatch: Clear relocation targets on a module removal
On Wed, Jan 18, 2023 at 2:08 PM Josh Poimboeuf <jpoimboe@kernel.org> wrote:
>
> On Wed, Jan 18, 2023 at 12:47:28PM -0800, Song Liu wrote:
> > From: Miroslav Benes <mbenes@suse.cz>
> >
> > Josh reported a bug:
> >
> > When the object to be patched is a module, and that module is
> > rmmod'ed and reloaded, it fails to load with:
> >
> > module: x86/modules: Skipping invalid relocation target, existing value is nonzero for type 2, loc 00000000ba0302e9, val ffffffffa03e293c
> > livepatch: failed to initialize patch 'livepatch_nfsd' for module 'nfsd' (-8)
> > livepatch: patch 'livepatch_nfsd' failed for module 'nfsd', refusing to load module 'nfsd'
> >
> > The livepatch module has a relocation which references a symbol
> > in the _previous_ loading of nfsd. When apply_relocate_add()
> > tries to replace the old relocation with a new one, it sees that
> > the previous one is nonzero and it errors out.
> >
> > On ppc64le, we have a similar issue:
> >
> > module_64: livepatch_nfsd: Expected nop after call, got e8410018 at e_show+0x60/0x548 [livepatch_nfsd]
> > livepatch: failed to initialize patch 'livepatch_nfsd' for module 'nfsd' (-8)
> > livepatch: patch 'livepatch_nfsd' failed for module 'nfsd', refusing to load module 'nfsd'
>
> Shouldn't there also be a fix for this powerpc issue?

There was a working version, but it was not very clean. We couldn't agree
on the path forward for powerpc, so we are hoping to ship the fix to x86 (and
s390?) first [1].

Thanks,
Song

[1] https://lore.kernel.org/live-patching/Y7hLvpHqgY0oJ4GY@alley/#t

\
 
 \ /
  Last update: 2023-03-26 23:48    [W:0.162 / U:0.048 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site