Re: [PATCH v3 2/3] livepatch: Move tests from lib/livepatch to selftests/livepatch

Shuah Khan
2023-12-11T21:56:17Z

On 12/7/23 12:19, mpdesouza@suse.com wrote:
> 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:
>>>
>>>> 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.
>>>>>
>>>>> This code moving will allow writing more complex tests, like
>>>>> for example an
>>>>> userspace C code that will call a livepatched kernel function.
>>>>>
>>>>> The modules are now built as out-of-tree
>>>>> modules, but being part of the kernel source means they will be
>>>>> maintained.
>>>>>
>>>>> 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.
>>>>>
>>>>> 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.
>>>>>
>>>>> The modules are built before running the selftests when using
>>>>> the
>>>>> kselftest invocations:
>>>>>
>>>>> make kselftest TARGETS=livepatch
>>>>> or
>>>>> make -C tools/testing/selftests/livepatch run_tests
>>>>>
>>>>
>>>> Quick question:
>>>>
>>>> - We have been building with CONFIG_LIVEPATCH_TEST=m to generate
>>>> the
>>>>   test modules at kernel build time
>>>>
>>>> - Our packaging filters out the selftest scripts and supporting
>>>> modules
>>>>   from the general kernel RPM package into their subpackages
>>>>
>>>> - Tests are run as part of CKI or other manual tests by
>>>> installing the
>>>>   pre-built packages from the previous step
>>>>
>>>>
>>>> After this patch, we would need to add something like the
>>>> following to
>>>> our kernel build, before packaging:
>>>>
>>>>   $ make KDIR=$(pwd) -C tools/testing/selftests/livepatch/
>>>>          ^^^^
>>>>
>>>> If this is the correct way to build the test modules for *this*
>>>> tree and
>>>> /lib/modules/$(shell uname -r)/build... it might be useful to
>>>> document
>>>> in the commit message as an alternative use case.
>
> That's right:
>
> $ make -C tools/testing/selftests/livepatch/
>
> is indeed the way to build the tests without running them. KDIR will be
> set to /lib/modules/$(shell uname -r)/build is empty.
>
> Yes, I can definitely add documentation about it inside the
> tools/testing/selftests/livepatch/README.
>

How does the default kselftest run work with these changes?

make ksefltest - does this still work as it did before this change?

thanks,
-- Shuah