Re: [PATCH RESEND v4 0/3] livepatch: Move modules to selftests and add a new test

[Joe Lawrence]

On Wed, Dec 20, 2023 at 01:53:11PM -0300, Marcos Paulo de Souza wrote:
> Changes in v4:
> * Documented how to compile the livepatch selftests without running the
>   tests (Joe)
> * Removed the mention to lib/livepatch on MAINTAINERS file, reported by
>   checkpatch.
> 
> Changes in v3:
> * Rebased on top of v6.6-rc5
> * The commits messages were improved (Thanks Petr!)
> * Created TEST_GEN_MODS_DIR variable to point to a directly that contains kernel
>   modules, and adapt selftests to build it before running the test.
> * Moved test_klp-call_getpid out of test_programs, since the gen_tar
>   would just copy the generated test programs to the livepatches dir,
>   and so scripts relying on test_programs/test_klp-call_getpid will fail.
> * Added a module_param for klp_pids, describing it's usage.
> * Simplified the call_getpid program to ignore the return of getpid syscall,
>   since we only want to make sure the process transitions correctly to the
>   patched stated
> * The test-syscall.sh not prints a log message showing the number of remaining
>   processes to transition into to livepatched state, and check_output expects it
>   to be 0.
> * Added MODULE_AUTHOR and MODULE_DESCRIPTION to test_klp_syscall.c
> 
> - Link to v3: https://lore.kernel.org/r/20231031-send-lp-kselftests-v3-0-2b1655c2605f@xxxxxxxx
> - Link to v2: https://lore.kernel.org/linux-kselftest/20220630141226.2802-1-mpdesouza@xxxxxxxx/
> 
> This patchset moves the current kernel testing livepatch modules from
> lib/livepatches to tools/testing/selftest/livepatch/test_modules, and compiles
> them as out-of-tree modules before testing.
> 
> There is also a new test being added. This new test exercises multiple processes
> calling a syscall, while a livepatch patched the syscall.
> 
> Why this move is an improvement:
> * The modules are now compiled as out-of-tree modules against the current
>   running kernel, making them capable of being tested on different systems with
>   newer or older kernels.
> * Such approach now needs kernel-devel package to be installed, since they are
>   out-of-tree modules. These can be generated by running "make rpm-pkg" in the
>   kernel source.
> 
> What needs to be solved:
> * Currently gen_tar only packages the resulting binaries of the tests, and not
>   the sources. For the current approach, the newly added modules would be
>   compiled and then packaged. It works when testing on a system with the same
>   kernel version. But it will fail when running on a machine with different kernel
>   version, since module was compiled against the kernel currently running.
> 
>   This is not a new problem, just aligning the expectations. For the current
>   approach to be truly system agnostic gen_tar would need to include the module
>   and program sources to be compiled in the target systems.
> 
> Thanks in advance!
>   Marcos
> 
> Signed-off-by: Marcos Paulo de Souza <mpdesouza@xxxxxxxx>
> ---
> Marcos Paulo de Souza (3):
>       kselftests: lib.mk: Add TEST_GEN_MODS_DIR variable
>       livepatch: Move tests from lib/livepatch to selftests/livepatch
>       selftests: livepatch: Test livepatching a heavily called syscall
> 
>  Documentation/dev-tools/kselftest.rst              |   4 +
>  MAINTAINERS                                        |   1 -
>  arch/s390/configs/debug_defconfig                  |   1 -
>  arch/s390/configs/defconfig                        |   1 -
>  lib/Kconfig.debug                                  |  22 ----
>  lib/Makefile                                       |   2 -
>  lib/livepatch/Makefile                             |  14 ---
>  tools/testing/selftests/lib.mk                     |  20 +++-
>  tools/testing/selftests/livepatch/Makefile         |   5 +-
>  tools/testing/selftests/livepatch/README           |  25 +++--
>  tools/testing/selftests/livepatch/config           |   1 -
>  tools/testing/selftests/livepatch/functions.sh     |  34 +++---
>  .../testing/selftests/livepatch/test-callbacks.sh  |  50 ++++-----
>  tools/testing/selftests/livepatch/test-ftrace.sh   |   6 +-
>  .../testing/selftests/livepatch/test-livepatch.sh  |  10 +-
>  .../selftests/livepatch/test-shadow-vars.sh        |   2 +-
>  tools/testing/selftests/livepatch/test-state.sh    |  18 ++--
>  tools/testing/selftests/livepatch/test-syscall.sh  |  53 ++++++++++
>  tools/testing/selftests/livepatch/test-sysfs.sh    |   6 +-
>  .../selftests/livepatch/test_klp-call_getpid.c     |  44 ++++++++
>  .../selftests/livepatch/test_modules/Makefile      |  20 ++++
>  .../test_modules}/test_klp_atomic_replace.c        |   0
>  .../test_modules}/test_klp_callbacks_busy.c        |   0
>  .../test_modules}/test_klp_callbacks_demo.c        |   0
>  .../test_modules}/test_klp_callbacks_demo2.c       |   0
>  .../test_modules}/test_klp_callbacks_mod.c         |   0
>  .../livepatch/test_modules}/test_klp_livepatch.c   |   0
>  .../livepatch/test_modules}/test_klp_shadow_vars.c |   0
>  .../livepatch/test_modules}/test_klp_state.c       |   0
>  .../livepatch/test_modules}/test_klp_state2.c      |   0
>  .../livepatch/test_modules}/test_klp_state3.c      |   0
>  .../livepatch/test_modules/test_klp_syscall.c      | 116 +++++++++++++++++++++
>  32 files changed, 334 insertions(+), 121 deletions(-)
> ---
> base-commit: 206ed72d6b33f53b2a8bf043f54ed6734121d26b
> change-id: 20231031-send-lp-kselftests-4c917dcd4565
> 
> Best regards,
> -- 
> Marcos Paulo de Souza <mpdesouza@xxxxxxxx>
> 

Hi Marcos,

I made it through retrofitting [1] to our current packaging scheme on
top of the patchset, no big surprises found.

With that, I'm happy to ack this version, unless you want to modify the
TEST_GEN_MODS_DIR / rsync behavior as I reported in my reply yesterday.
(Not a show stopper IMHO, but I'll leave that up to kselftest folks.)

Reviewed-by: Joe Lawrence <joe.lawrence@xxxxxxxxxx>

[1] https://gitlab.com/cki-project/kernel-ark/-/merge_requests/2844/commits

--
Joe