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Date:   Tue, 12 Dec 2023 10:19:41 +0100
From:   Paul =?utf-8?Q?Heidekr=C3=BCger?= <paul.heidekrueger@tum.de>
To:     Andrey Konovalov <andreyknvl@gmail.com>
Cc:     Marco Elver <elver@google.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>
Subject: Re: [PATCH v3 1/3] kasan: switch kunit tests to console tracepoints
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On 12.12.2023 00:37, Andrey Konovalov wrote:
> On Tue, Dec 12, 2023 at 12:35 AM Paul Heidekrüger
> <paul.heidekrueger@tum.de> wrote:
> >
> > Using CONFIG_FTRACE=y instead of CONFIG_TRACEPOINTS=y produces the same error
> > for me.
> >
> > So
> >
> >         CONFIG_KUNIT=y
> >         CONFIG_KUNIT_ALL_TESTS=n
> >         CONFIG_FTRACE=y
> >         CONFIG_KASAN=y
> >         CONFIG_KASAN_GENERIC=y
> >         CONFIG_KASAN_KUNIT_TEST=y
> >
> > produces
> >
> >         ➜   ./tools/testing/kunit/kunit.py run --kunitconfig=mm/kasan/.kunitconfig --arch=arm64
> >         Configuring KUnit Kernel ...
> >         Regenerating .config ...
> >         Populating config with:
> >         $ make ARCH=arm64 O=.kunit olddefconfig CC=clang
> >         ERROR:root:Not all Kconfig options selected in kunitconfig were in the generated .config.
> >         This is probably due to unsatisfied dependencies.
> >         Missing: CONFIG_KASAN_KUNIT_TEST=y
> >
> > By that error message, CONFIG_FTRACE appears to be present in the generated
> > config, but CONFIG_KASAN_KUNIT_TEST still isn't. Presumably,
> > CONFIG_KASAN_KUNIT_TEST is missing because of an unsatisfied dependency, which
> > must be CONFIG_TRACEPOINTS, unless I'm missing something ...
> >
> > If I just generate an arm64 defconfig and select CONFIG_FTRACE=y,
> > CONFIG_TRACEPOINTS=y shows up in my .config. So, maybe this is kunit.py-related
> > then?
> >
> > Andrey, you said that the tests have been working for you; are you running 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=y in addition to CONFIG_FTRACE=y, it works.

CONFIG_STACK_TRACER selects CONFIG_FUNCTION_TRACER, CONFIG_FUNCTION_TRACER 
selects CONFIG_GENERIC_TRACER, CONFIG_GENERIC_TRACER selects CONFIG_TRACING, and 
CONFIG_TRACING selects CONFIG_TRACEPOINTS. 

CONFIG_BLK_DEV_IO_TRACE=y also works instead of CONFIG_STACK_TRACER=y, as it 
directly selects CONFIG_TRACEPOINTS. 

CONFIG_FTRACE=y on its own does not appear suffice for kunit.py on arm64.

I believe the reason my .kunitconfig as well as the existing 
mm/kfence/.kunitconfig work on X86 is because CONFIG_TRACEPOINTS=y is present 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 have to 
test that. That could be a third patch.

What do you think?

Many thanks,
Paul