Re: [RFC PATCH v2 1/3] Add KUnit Struct to Current Task

[Alan Maguire]

On Tue, 24 Mar 2020, Patricia Alfonso wrote:

> On Tue, Mar 24, 2020 at 9:40 AM Alan Maguire <alan.maguire@xxxxxxxxxx> wrote:
> >
> >
> > On Thu, 19 Mar 2020, Patricia Alfonso wrote:
> >
> > > In order to integrate debugging tools like KASAN into the KUnit
> > > framework, add KUnit struct to the current task to keep track of the
> > > current KUnit test.
> > >
> > > Signed-off-by: Patricia Alfonso <trishalfonso@xxxxxxxxxx>
> > > ---
> > >  include/linux/sched.h | 4 ++++
> > >  1 file changed, 4 insertions(+)
> > >
> > > diff --git a/include/linux/sched.h b/include/linux/sched.h
> > > index 04278493bf15..1fbfa0634776 100644
> > > --- a/include/linux/sched.h
> > > +++ b/include/linux/sched.h
> > > @@ -1180,6 +1180,10 @@ struct task_struct {
> > >       unsigned int                    kasan_depth;
> > >  #endif
> > >
> > > +#if IS_BUILTIN(CONFIG_KUNIT)
> >
> > This patch set looks great! You might have noticed I
> > refreshed the kunit resources stuff to incorporate
> > feedback from Brendan, but I don't think any API changes
> > were made that should have consequences for your code
> > (I'm building with your patches on top to make sure).
> > I'd suggest promoting from RFC to v3 on the next round
> > unless anyone objects.
> >
> > As Dmitry suggested, the above could likely be changed to be
> > "#ifdef CONFIG_KUNIT" as kunit can be built as a
> > module also. More on this in patch 2..
> >
> I suppose this could be changed so that this can be used in possible
> future scenarios, but for now, since built-in things can't rely on
> modules, the KASAN integration relies on KUnit being built-in.
>

I think we can get around that. I've tried tweaking the resources
patchset such that the functions you need in KASAN (which
is builtin) are declared as "static inline" in include/kunit/test.h;
doing this allows us to build kunit and test_kasan as a
module while supporting the builtin functionality required to
retrieve and use kunit resources within KASAN itself.  

The impact of this amounts to a few functions, but it would
require a rebase of your changes. I'll send out a  v3 of the
resources patches shortly; I just want to do some additional
testing on them. I can also send you the modified versions of
your patches that I used to test with.

With these changes I can run the tests on baremetal
x86_64 by modprobe'ing test_kasan. However I see a few failures:

[   87.577012]  # kasan_memchr: EXPECTATION FAILED at lib/test_kasan.c:509
        Expected kasan_data->report_expected == kasan_data->report_found, 
but
                kasan_data->report_expected == 1
                kasan_data->report_found == 0
[   87.577104]  not ok 30 - kasan_memchr
[   87.603823]  # kasan_memcmp: EXPECTATION FAILED at lib/test_kasan.c:523
        Expected kasan_data->report_expected == kasan_data->report_found, 
but
                kasan_data->report_expected == 1
                kasan_data->report_found == 0
[   87.603929]  not ok 31 - kasan_memcmp
[   87.630644]  # kasan_strings: EXPECTATION FAILED at 
lib/test_kasan.c:544
        Expected kasan_data->report_expected == kasan_data->report_found, 
but
                kasan_data->report_expected == 1
                kasan_data->report_found == 0
[   87.630910]  # kasan_strings: EXPECTATION FAILED at 
lib/test_kasan.c:546
        Expected kasan_data->report_expected == kasan_data->report_found, 
but
                kasan_data->report_expected == 1
                kasan_data->report_found == 0
[   87.654037]  # kasan_strings: EXPECTATION FAILED at 
lib/test_kasan.c:548
        Expected kasan_data->report_expected == kasan_data->report_found, 
but
                kasan_data->report_expected == 1
                kasan_data->report_found == 0
[   87.677179]  # kasan_strings: EXPECTATION FAILED at 
lib/test_kasan.c:550
        Expected kasan_data->report_expected == kasan_data->report_found, 
but
                kasan_data->report_expected == 1
                kasan_data->report_found == 0
[   87.700242]  # kasan_strings: EXPECTATION FAILED at 
lib/test_kasan.c:552
        Expected kasan_data->report_expected == kasan_data->report_found, 
but
                kasan_data->report_expected == 1
                kasan_data->report_found == 0
[   87.723336]  # kasan_strings: EXPECTATION FAILED at 
lib/test_kasan.c:554
        Expected kasan_data->report_expected == kasan_data->report_found, 
but
                kasan_data->report_expected == 1
                kasan_data->report_found == 0
[   87.746304]  not ok 32 - kasan_strings

The above three tests consistently fail while everything
else passes, and happen irrespective of whether kunit
is built as a module or built-in.  Let me know if you 
need any more info to debug (I built the kernel with
CONFIG_SLUB=y if that matters).

Thanks!

Alan


> > > +     struct kunit                    *kunit_test;
> > > +#endif /* IS_BUILTIN(CONFIG_KUNIT) */
> > > +
> > >  #ifdef CONFIG_FUNCTION_GRAPH_TRACER
> > >       /* Index of current stored address in ret_stack: */
> > >       int                             curr_ret_stack;
> > > --
> > > 2.25.1.696.g5e7596f4ac-goog
> > >
> > >
> 
> -- 
> Best,
> Patricia
>