linux-kernel - Re: [PATCH v3 0/3] livepatch: Move modules to selftests and add a new test

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Message-ID: <idd6uyqhlx42pteruavjyviyhdy63q47bjes3zwgfdsndxofgp@jhfwrvktpkv4>
Date:   Thu, 30 Nov 2023 10:42:06 -0300
From:   Marcos Paulo de Souza <mpdesouza@...e.de>
To:     Marcos Paulo de Souza <mpdesouza@...e.com>
Cc:     Shuah Khan <shuah@...nel.org>, Jonathan Corbet <corbet@....net>,
        Heiko Carstens <hca@...ux.ibm.com>,
        Vasily Gorbik <gor@...ux.ibm.com>,
        Alexander Gordeev <agordeev@...ux.ibm.com>,
        Christian Borntraeger <borntraeger@...ux.ibm.com>,
        Sven Schnelle <svens@...ux.ibm.com>,
        Josh Poimboeuf <jpoimboe@...nel.org>,
        Jiri Kosina <jikos@...nel.org>,
        Miroslav Benes <mbenes@...e.cz>,
        Petr Mladek <pmladek@...e.com>,
        Joe Lawrence <joe.lawrence@...hat.com>,
        linux-kselftest@...r.kernel.org, linux-doc@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-s390@...r.kernel.org,
        live-patching@...r.kernel.org
Subject: Re: [PATCH v3 0/3] livepatch: Move modules to selftests and add a
 new test

Humble ping :)

On Tue, Oct 31, 2023 at 06:10:50PM -0300, Marcos Paulo de Souza wrote:
> 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.
> 
> I'm sending the patches now so it can be discussed before Plumbers.
> 
> Thanks in advance!
>   Marcos
> 
> To: Shuah Khan <shuah@...nel.org>
> To: Jonathan Corbet <corbet@....net>
> To: Heiko Carstens <hca@...ux.ibm.com>
> To: Vasily Gorbik <gor@...ux.ibm.com>
> To: Alexander Gordeev <agordeev@...ux.ibm.com>
> To: Christian Borntraeger <borntraeger@...ux.ibm.com>
> To: Sven Schnelle <svens@...ux.ibm.com>
> To: Josh Poimboeuf <jpoimboe@...nel.org>
> To: Jiri Kosina <jikos@...nel.org>
> To: Miroslav Benes <mbenes@...e.cz>
> To: Petr Mladek <pmladek@...e.com>
> To: Joe Lawrence <joe.lawrence@...hat.com>
> Cc: linux-kselftest@...r.kernel.org
> Cc: linux-doc@...r.kernel.org
> Cc: linux-kernel@...r.kernel.org
> Cc: linux-s390@...r.kernel.org
> Cc: live-patching@...r.kernel.org
> Signed-off-by: Marcos Paulo de Souza <mpdesouza@...e.com>
> 
> 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
> 
> The v2 can be seen here:
> https://lore.kernel.org/linux-kselftest/20220630141226.2802-1-mpdesouza@suse.com/
> 
> ---
> 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 +
>  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           |  17 +--
>  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 +++++++++++++++++++++
>  31 files changed, 325 insertions(+), 121 deletions(-)
> ---
> base-commit: 6489bf2e1df1c84e9bcd4694029ff35b39fd3397
> change-id: 20231031-send-lp-kselftests-4c917dcd4565
> 
> Best regards,
> -- 
> Marcos Paulo de Souza <mpdesouza@...e.com>
>