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From:   Marco Elver <elver@google.com>
Date:   Tue, 12 Dec 2023 10:32:45 +0100
Message-ID: <CANpmjNN5Q+byA3sWv1uB_R=QYQxKg5YsLKayqv7WNWokkL5H4Q@mail.gmail.com>
Subject: Re: [PATCH v3 1/3] kasan: switch kunit tests to console tracepoints
To:     =?UTF-8?Q?Paul_Heidekr=C3=BCger?= <paul.heidekrueger@tum.de>
Cc:     Andrey Konovalov <andreyknvl@gmail.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Peter Collingbourne <pcc@google.com>,
        andrey.konovalov@linux.dev,
        Andrew Morton <akpm@linux-foundation.org>,
        Alexander Potapenko <glider@google.com>,
        Dmitry Vyukov <dvyukov@google.com>,
        Andrey Ryabinin <ryabinin.a.a@gmail.com>,
        kasan-dev@googlegroups.com, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org,
        Andrey Konovalov <andreyknvl@google.com>,
        Masami Hiramatsu <mhiramat@kernel.org>,
        linux-trace-kernel@vger.kernel.org,
        Nick Desaulniers <ndesaulniers@google.com>
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On Tue, 12 Dec 2023 at 10:19, Paul Heidekr=C3=BCger <paul.heidekrueger@tum.=
de> wrote:
>
> On 12.12.2023 00:37, Andrey Konovalov wrote:
> > On Tue, Dec 12, 2023 at 12:35=E2=80=AFAM Paul Heidekr=C3=BCger
> > <paul.heidekrueger@tum.de> wrote:
> > >
> > > Using CONFIG_FTRACE=3Dy instead of CONFIG_TRACEPOINTS=3Dy produces th=
e same error
> > > for me.
> > >
> > > So
> > >
> > >         CONFIG_KUNIT=3Dy
> > >         CONFIG_KUNIT_ALL_TESTS=3Dn
> > >         CONFIG_FTRACE=3Dy
> > >         CONFIG_KASAN=3Dy
> > >         CONFIG_KASAN_GENERIC=3Dy
> > >         CONFIG_KASAN_KUNIT_TEST=3Dy
> > >
> > > produces
> > >
> > >         =E2=9E=9C   ./tools/testing/kunit/kunit.py run --kunitconfig=
=3Dmm/kasan/.kunitconfig --arch=3Darm64
> > >         Configuring KUnit Kernel ...
> > >         Regenerating .config ...
> > >         Populating config with:
> > >         $ make ARCH=3Darm64 O=3D.kunit olddefconfig CC=3Dclang
> > >         ERROR:root:Not all Kconfig options selected in kunitconfig we=
re in the generated .config.
> > >         This is probably due to unsatisfied dependencies.
> > >         Missing: CONFIG_KASAN_KUNIT_TEST=3Dy
> > >
> > > By that error message, CONFIG_FTRACE appears to be present in the gen=
erated
> > > config, but CONFIG_KASAN_KUNIT_TEST still isn't. Presumably,
> > > CONFIG_KASAN_KUNIT_TEST is missing because of an unsatisfied dependen=
cy, which
> > > must be CONFIG_TRACEPOINTS, unless I'm missing something ...
> > >
> > > If I just generate an arm64 defconfig and select CONFIG_FTRACE=3Dy,
> > > CONFIG_TRACEPOINTS=3Dy shows up in my .config. So, maybe this is kuni=
t.py-related
> > > then?
> > >
> > > Andrey, you said that the tests have been working for you; are you ru=
nning them
> > > with kunit.py?
> >
> > No, I just run the kernel built with a config file that I put together
> > based on defconfig.
>
> Ah. I believe I've figured it out.
>
> When I add CONFIG_STACK_TRACER=3Dy in addition to CONFIG_FTRACE=3Dy, it w=
orks.

CONFIG_FTRACE should be enough - maybe also check x86 vs. arm64 to debug mo=
re.

> CONFIG_STACK_TRACER selects CONFIG_FUNCTION_TRACER, CONFIG_FUNCTION_TRACE=
R
> selects CONFIG_GENERIC_TRACER, CONFIG_GENERIC_TRACER selects CONFIG_TRACI=
NG, and
> CONFIG_TRACING selects CONFIG_TRACEPOINTS.
>
> CONFIG_BLK_DEV_IO_TRACE=3Dy also works instead of CONFIG_STACK_TRACER=3Dy=
, as it
> directly selects CONFIG_TRACEPOINTS.
>
> CONFIG_FTRACE=3Dy on its own does not appear suffice for kunit.py on arm6=
4.

When you build manually with just CONFIG_FTRACE, is CONFIG_TRACEPOINTS enab=
led?

> I believe the reason my .kunitconfig as well as the existing
> mm/kfence/.kunitconfig work on X86 is because CONFIG_TRACEPOINTS=3Dy is p=
resent in
> an X86 defconfig.
>
> Does this make sense?
>
> Would you welcome a patch addressing this for the existing
> mm/kfence/.kunitconfig?
>
> I would also like to submit a patch for an mm/kasan/.kunitconfig. Do you =
think
> that would be helpful too?
>
> FWICT, kernel/kcsan/.kunitconfig might also be affected since
> CONFIG_KCSAN_KUNIT_TEST also depends on CONFIG_TRACEPOITNS, but I would h=
ave to
> test that. That could be a third patch.

I'd support figuring out the minimal config (CONFIG_FTRACE or
something else?) that satisfies the TRACEPOINTS dependency. I always
thought CONFIG_FTRACE ought to be the one config option, but maybe
something changed.

Also maybe one of the tracing maintainers can help untangle what's
going on here.

Thanks,
-- Marco