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Subject: Re: [PATCH v3 2/3] livepatch: Move tests from lib/livepatch to
 selftests/livepatch
From:   Marcos Paulo de Souza <mpdesouza@suse.com>
To:     Shuah Khan <skhan@linuxfoundation.org>,
        Joe Lawrence <joe.lawrence@redhat.com>,
        Miroslav Benes <mbenes@suse.cz>
Cc:     Shuah Khan <shuah@kernel.org>, Jonathan Corbet <corbet@lwn.net>,
        Heiko Carstens <hca@linux.ibm.com>,
        Vasily Gorbik <gor@linux.ibm.com>,
        Alexander Gordeev <agordeev@linux.ibm.com>,
        Christian Borntraeger <borntraeger@linux.ibm.com>,
        Sven Schnelle <svens@linux.ibm.com>,
        Josh Poimboeuf <jpoimboe@kernel.org>,
        Jiri Kosina <jikos@kernel.org>, Petr Mladek <pmladek@suse.com>,
        linux-kselftest@vger.kernel.org, linux-doc@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org,
        live-patching@vger.kernel.org
Date:   Mon, 11 Dec 2023 23:01:02 -0300
In-Reply-To: <2c4f2771-0557-4b44-9c98-6bd2e6930d2f@linuxfoundation.org>
References: <20231031-send-lp-kselftests-v3-0-2b1655c2605f@suse.com>
         <20231031-send-lp-kselftests-v3-2-2b1655c2605f@suse.com>
         <ZWn7dEzVWoKxycmy@redhat.com>
         <alpine.LSU.2.21.2312061543280.13051@pobox.suse.cz>
         <273a86d6-d220-fdcf-3c2f-70516c519ff9@redhat.com>
         <57fb9f30afbaddb09def96aac11c45296a59a277.camel@suse.com>
         <2c4f2771-0557-4b44-9c98-6bd2e6930d2f@linuxfoundation.org>
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On Mon, 2023-12-11 at 14:56 -0700, Shuah Khan wrote:
> On 12/7/23 12:19, mpdesouza@suse.com=C2=A0wrote:
> > On Thu, 2023-12-07 at 10:20 -0500, Joe Lawrence wrote:
> > > On 12/6/23 10:05, Miroslav Benes wrote:
> > > > On Fri, 1 Dec 2023, Joe Lawrence wrote:
> > > >=20
> > > > > On Tue, Oct 31, 2023 at 06:10:52PM -0300, Marcos Paulo de
> > > > > Souza
> > > > > wrote:
> > > > > > The modules are being moved from lib/livepatch to
> > > > > > tools/testing/selftests/livepatch/test_modules.
> > > > > >=20
> > > > > > This code moving will allow writing more complex tests,
> > > > > > like
> > > > > > for example an
> > > > > > userspace C code that will call a livepatched kernel
> > > > > > function.
> > > > > >=20
> > > > > > The modules are now built as out-of-tree
> > > > > > modules, but being part of the kernel source means they
> > > > > > will be
> > > > > > maintained.
> > > > > >=20
> > > > > > Another advantage of the code moving is to be able to
> > > > > > easily
> > > > > > change,
> > > > > > debug and rebuild the tests by running make on the
> > > > > > selftests/livepatch directory,
> > > > > > which is not currently possible since the modules on
> > > > > > lib/livepatch are
> > > > > > build and installed using the "modules" target.
> > > > > >=20
> > > > > > The current approach also keeps the ability to execute the
> > > > > > tests manually by
> > > > > > executing the scripts inside selftests/livepatch directory,
> > > > > > as
> > > > > > it's currently
> > > > > > supported. If the modules are modified, they needed to be
> > > > > > rebuilt before running
> > > > > > the scripts though.
> > > > > >=20
> > > > > > The modules are built before running the selftests when
> > > > > > using
> > > > > > the
> > > > > > kselftest invocations:
> > > > > >=20
> > > > > > 	make kselftest TARGETS=3Dlivepatch
> > > > > > or
> > > > > > 	make -C tools/testing/selftests/livepatch
> > > > > > run_tests
> > > > > >=20
> > > > >=20
> > > > > Quick question:
> > > > >=20
> > > > > - We have been building with CONFIG_LIVEPATCH_TEST=3Dm to
> > > > > generate
> > > > > the
> > > > > =C2=A0=C2=A0 test modules at kernel build time
> > > > >=20
> > > > > - Our packaging filters out the selftest scripts and
> > > > > supporting
> > > > > modules
> > > > > =C2=A0=C2=A0 from the general kernel RPM package into their subpa=
ckages
> > > > >=20
> > > > > - Tests are run as part of CKI or other manual tests by
> > > > > installing the
> > > > > =C2=A0=C2=A0 pre-built packages from the previous step
> > > > >=20
> > > > >=20
> > > > > After this patch, we would need to add something like the
> > > > > following to
> > > > > our kernel build, before packaging:
> > > > >=20
> > > > > =C2=A0=C2=A0 $ make KDIR=3D$(pwd) -C tools/testing/selftests/live=
patch/
> > > > > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 ^^^^
> > > > >=20
> > > > > If this is the correct way to build the test modules for
> > > > > *this*
> > > > > tree and
> > > > > /lib/modules/$(shell uname -r)/build... it might be useful to
> > > > > document
> > > > > in the commit message as an alternative use case.
> >=20
> > That's right:
> >=20
> > $ make -C tools/testing/selftests/livepatch/
> >=20
> > is indeed the way to build the tests without running them. KDIR
> > will be
> > set to=C2=A0 /lib/modules/$(shell uname -r)/build is empty.
> >=20
> > Yes, I can definitely add documentation about it inside the
> > tools/testing/selftests/livepatch/README.
> >=20
>=20
> How does the default kselftest run work with these changes?
>=20
> make ksefltest - does this still work as it did before this change?

Yes,

make kselftest TARGETS=3Dlivepatch

works the same as before. As well the

make -C tools/testing/selftests/livepatch run_tests

Both ways work as before.
>=20
> thanks,
> -- Shuah
>=20