lkml.org 
[lkml]   [2018]   [Mar]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v10 00/10] livepatch: Atomic replace feature
On Wed 2018-03-07 16:55:53, Joe Lawrence wrote:
> On 03/07/2018 03:20 AM, Petr Mladek wrote:
> > The atomic replace allows to create cumulative patches. They
> > are useful when you maintain many livepatches and want to remove
> > one that is lower on the stack. In addition it is very useful when
> > more patches touch the same function and there are dependencies
> > between them.
> >
> >
> > Changes against v9:
> >
> > + Fixed check of valid NOPs for already loaded objects,
> > regression introduced in v9 [Joe, Mirek]
> > + Allow to replace even disabled patches [Evgenii]
> >
> > Changes against v8:
> >
> > + Fixed handling of statically defined struct klp_object
> > with empty array of functions [Joe, Mirek]
> > + Removed redundant func->new_func assignment for NOPs [Mirek]
> > + Improved some wording [Mirek]
> >
> > [ ... snip ... ]
>
> Hi Petr,
>
> I tried updating the test cases I was adding in "[PATCH v0 0/3]
> additional cumulative livepatch doc/samples" and although one of the
> cases is better than before, I'm running into a new issue: an expected
> pre-unpatch callback is not executed (its obj->patched is false).
>
> Here's the updated test case:
>
> Test 11
> -------
>
> - load livepatch
> - load second livepatch (atomic replace) <- callbacks ok
> - disable second livepatch <- pre-unpatch skipped
> - unload livepatch
> - unload second livepatch
>
> % insmod samples/livepatch/livepatch-callbacks-demo.ko
> [ 2306.806046] livepatch: enabling patch 'livepatch_callbacks_demo'
> [ 2306.806048] livepatch: 'livepatch_callbacks_demo': initializing patching transition
> [ 2306.806083] livepatch_callbacks_demo: pre_patch_callback: vmlinux
> [ 2306.806083] livepatch: 'livepatch_callbacks_demo': starting patching transition
> [ 2307.743170] livepatch: 'livepatch_callbacks_demo': completing patching transition
> [ 2307.743317] livepatch_callbacks_demo: post_patch_callback: vmlinux
> [ 2307.743319] livepatch: 'livepatch_callbacks_demo': patching complet
>
> % insmod samples/livepatch/livepatch-callbacks-demo2.ko replace=1
> [ 2316.161804] livepatch: enabling patch 'livepatch_callbacks_demo2'
> [ 2316.161807] livepatch: 'livepatch_callbacks_demo2': initializing patching transition
> [ 2316.161842] livepatch_callbacks_demo2: pre_patch_callback: vmlinux
> [ 2316.161843] livepatch: 'livepatch_callbacks_demo2': starting patching transition
> [ 2317.727141] livepatch: 'livepatch_callbacks_demo2': completing patching transition
> [ 2317.727254] livepatch_callbacks_demo2: post_patch_callback: vmlinux
> [ 2317.727255] livepatch: 'livepatch_callbacks_demo2': patching complete
>
> % echo 0 > /sys/kernel/livepatch/livepatch_callbacks_demo2/enabled
> [ 2328.995854] livepatch: 'livepatch_callbacks_demo2': initializing unpatching transition
> [ 2328.995898] livepatch: 'livepatch_callbacks_demo2': starting unpatching transition
> [ 2330.719234] livepatch: 'livepatch_callbacks_demo2': completing unpatching transition
> [ 2330.719597] livepatch_callbacks_demo2: post_unpatch_callback: vmlinux
> [ 2330.719599] livepatch: 'livepatch_callbacks_demo2': unpatching complete
>
> % rmmod samples/livepatch/livepatch-callbacks-demo2.ko
> % rmmod samples/livepatch/livepatch-callbacks-demo.ko
>
> Running against v10, callbacks seem to be good up until I disable an
> atomic replace patch. My understanding is that the original patch's
> unpatch callbacks should be skipped (as they were). I was surprised to
> see that atomic replacement patch only ran it's post-unpatch callback.

Great catch!

I guess that it is caused by the heuristic used in
klp_unpatch_object() to decide whether the object is patched
or not.

We need to change the state only when manipulating the
statically defined functions.

Thanks a lot for so extensive testing!!!

Best Regards,
Petr

\
 
 \ /
  Last update: 2018-03-08 16:02    [W:0.243 / U:0.912 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site