| Message ID | 20240109-send-lp-kselftests-v5-0-364d59a69f12@suse.com |
|---|---|
| Headers | show |
| Series | livepatch: Move modules to selftests and add a new test | expand |
On Tue 2024-01-09 21:24:54, Marcos Paulo de Souza wrote: > Add TEST_GEN_MODS_DIR variable for kselftests. It can point to > a directory containing kernel modules that will be used by > selftest scripts. > > The modules are built as external modules for the running kernel. > As a result they are always binary compatible and the same tests > can be used for older or newer kernels. > > The build requires "kernel-devel" package to be installed. > For example, in the upstream sources, the rpm devel package > is produced by "make rpm-pkg" > > The modules can be built independently by > > make -C tools/testing/selftests/livepatch/ > > or they will be automatically built before running the tests via > > make -C tools/testing/selftests/livepatch/ run_tests > > Note that they are _not_ built when running the standalone > tests by calling, for example, ./test-state.sh. > > Along with TEST_GEN_MODS_DIR, it was necessary to create a new install > rule. INSTALL_MODS_RULE is needed because INSTALL_SINGLE_RULE would > copy the entire TEST_GEN_MODS_DIR directory to the destination, even > the files created by Kbuild to compile the modules. The new install > rule copies only the .ko files, as we would expect the gen_tar to work. > > Reviewed-by: Joe Lawrence <joe.lawrence@redhat.com> > Signed-off-by: Marcos Paulo de Souza <mpdesouza@suse.com> I am not export on kbuild. But it looks reasonable and works for me. Reviewed-by: Petr Mladek <pmladek@suse.com> Best Regards, Petr
On Tue 2024-01-09 21:24:56, Marcos Paulo de Souza wrote: > The test proves that a syscall can be livepatched. It is interesting > because syscalls are called a tricky way. Also the process gets > livepatched either when sleeping in the userspace or when entering > or leaving the kernel space. > > The livepatch is a bit tricky: > 1. The syscall function name is architecture specific. Also > ARCH_HAS_SYSCALL_WRAPPER must be taken in account. > > 2. The syscall must stay working the same way for other processes > on the system. It is solved by decrementing a counter only > for PIDs of the test processes. It means that the test processes > has to call the livepatched syscall at least once. > > The test creates one userspace process per online cpu. The processes > are calling getpid in a busy loop. The intention is to create random > locations when the livepatch gets enabled. Nothing is guarantted. > The magic is in the randomness. > > Reviewed-by: Joe Lawrence <joe.lawrence@redhat.com> > Signed-off-by: Marcos Paulo de Souza <mpdesouza@suse.com> Reviewed-by: Petr Mladek <pmladek@suse.com> Best Regards, Petr
Changes in v5: * Fixed an issue found by Joe that copied Kbuild files along with the test modules to the installation directory. * Added Joe Lawrense review tags. 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@suse.com - Link to v2: https://lore.kernel.org/linux-kselftest/20220630141226.2802-1-mpdesouza@suse.com/ 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@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 + 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 | 25 ++++- 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, 339 insertions(+), 121 deletions(-) --- base-commit: 89ecef4cb0ac442d5ad48c1aae1e2e1e7744d46f change-id: 20231031-send-lp-kselftests-4c917dcd4565 Best regards,