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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 | ====================== Linux Kernel Selftests ====================== The kernel contains a set of "self tests" under the tools/testing/selftests/ directory. These are intended to be small tests to exercise individual code paths in the kernel. Tests are intended to be run after building, installing and booting a kernel. Kselftest from mainline can be run on older stable kernels. Running tests from mainline offers the best coverage. Several test rings run mainline kselftest suite on stable releases. The reason is that when a new test gets added to test existing code to regression test a bug, we should be able to run that test on an older kernel. Hence, it is important to keep code that can still test an older kernel and make sure it skips the test gracefully on newer releases. You can find additional information on Kselftest framework, how to write new tests using the framework on Kselftest wiki: https://kselftest.wiki.kernel.org/ On some systems, hot-plug tests could hang forever waiting for cpu and memory to be ready to be offlined. A special hot-plug target is created to run the full range of hot-plug tests. In default mode, hot-plug tests run in safe mode with a limited scope. In limited mode, cpu-hotplug test is run on a single cpu as opposed to all hotplug capable cpus, and memory hotplug test is run on 2% of hotplug capable memory instead of 10%. kselftest runs as a userspace process. Tests that can be written/run in userspace may wish to use the `Test Harness`_. Tests that need to be run in kernel space may wish to use a `Test Module`_. Running the selftests (hotplug tests are run in limited mode) ============================================================= To build the tests:: $ make headers $ make -C tools/testing/selftests To run the tests:: $ make -C tools/testing/selftests run_tests To build and run the tests with a single command, use:: $ make kselftest Note that some tests will require root privileges. Kselftest supports saving output files in a separate directory and then running tests. To locate output files in a separate directory two syntaxes are supported. In both cases the working directory must be the root of the kernel src. This is applicable to "Running a subset of selftests" section below. To build, save output files in a separate directory with O= :: $ make O=/tmp/kselftest kselftest To build, save output files in a separate directory with KBUILD_OUTPUT :: $ export KBUILD_OUTPUT=/tmp/kselftest; make kselftest The O= assignment takes precedence over the KBUILD_OUTPUT environment variable. The above commands by default run the tests and print full pass/fail report. Kselftest supports "summary" option to make it easier to understand the test results. Please find the detailed individual test results for each test in /tmp/testname file(s) when summary option is specified. This is applicable to "Running a subset of selftests" section below. To run kselftest with summary option enabled :: $ make summary=1 kselftest Running a subset of selftests ============================= You can use the "TARGETS" variable on the make command line to specify single test to run, or a list of tests to run. To run only tests targeted for a single subsystem:: $ make -C tools/testing/selftests TARGETS=ptrace run_tests You can specify multiple tests to build and run:: $ make TARGETS="size timers" kselftest To build, save output files in a separate directory with O= :: $ make O=/tmp/kselftest TARGETS="size timers" kselftest To build, save output files in a separate directory with KBUILD_OUTPUT :: $ export KBUILD_OUTPUT=/tmp/kselftest; make TARGETS="size timers" kselftest Additionally you can use the "SKIP_TARGETS" variable on the make command line to specify one or more targets to exclude from the TARGETS list. To run all tests but a single subsystem:: $ make -C tools/testing/selftests SKIP_TARGETS=ptrace run_tests You can specify multiple tests to skip:: $ make SKIP_TARGETS="size timers" kselftest You can also specify a restricted list of tests to run together with a dedicated skiplist:: $ make TARGETS="breakpoints size timers" SKIP_TARGETS=size kselftest See the top-level tools/testing/selftests/Makefile for the list of all possible targets. Running the full range hotplug selftests ======================================== To build the hotplug tests:: $ make -C tools/testing/selftests hotplug To run the hotplug tests:: $ make -C tools/testing/selftests run_hotplug Note that some tests will require root privileges. Install selftests ================= You can use the "install" target of "make" (which calls the `kselftest_install.sh` tool) to install selftests in the default location (`tools/testing/selftests/kselftest_install`), or in a user specified location via the `INSTALL_PATH` "make" variable. To install selftests in default location:: $ make -C tools/testing/selftests install To install selftests in a user specified location:: $ make -C tools/testing/selftests install INSTALL_PATH=/some/other/path Running installed selftests =========================== Found in the install directory, as well as in the Kselftest tarball, is a script named `run_kselftest.sh` to run the tests. You can simply do the following to run the installed Kselftests. Please note some tests will require root privileges:: $ cd kselftest_install $ ./run_kselftest.sh To see the list of available tests, the `-l` option can be used:: $ ./run_kselftest.sh -l The `-c` option can be used to run all the tests from a test collection, or the `-t` option for specific single tests. Either can be used multiple times:: $ ./run_kselftest.sh -c size -c seccomp -t timers:posix_timers -t timer:nanosleep For other features see the script usage output, seen with the `-h` option. Timeout for selftests ===================== Selftests are designed to be quick and so a default timeout is used of 45 seconds for each test. Tests can override the default timeout by adding a settings file in their directory and set a timeout variable there to the configured a desired upper timeout for the test. Only a few tests override the timeout with a value higher than 45 seconds, selftests strives to keep it that way. Timeouts in selftests are not considered fatal because the system under which a test runs may change and this can also modify the expected time it takes to run a test. If you have control over the systems which will run the tests you can configure a test runner on those systems to use a greater or lower timeout on the command line as with the `-o` or the `--override-timeout` argument. For example to use 165 seconds instead one would use:: $ ./run_kselftest.sh --override-timeout 165 You can look at the TAP output to see if you ran into the timeout. Test runners which know a test must run under a specific time can then optionally treat these timeouts then as fatal. Packaging selftests =================== In some cases packaging is desired, such as when tests need to run on a different system. To package selftests, run:: $ make -C tools/testing/selftests gen_tar This generates a tarball in the `INSTALL_PATH/kselftest-packages` directory. By default, `.gz` format is used. The tar compression format can be overridden by specifying a `FORMAT` make variable. Any value recognized by `tar's auto-compress`_ option is supported, such as:: $ make -C tools/testing/selftests gen_tar FORMAT=.xz `make gen_tar` invokes `make install` so you can use it to package a subset of tests by using variables specified in `Running a subset of selftests`_ section:: $ make -C tools/testing/selftests gen_tar TARGETS="size" FORMAT=.xz .. _tar's auto-compress: https://www.gnu.org/software/tar/manual/html_node/gzip.html#auto_002dcompress Contributing new tests ====================== In general, the rules for selftests are * Do as much as you can if you're not root; * Don't take too long; * Don't break the build on any architecture, and * Don't cause the top-level "make run_tests" to fail if your feature is unconfigured. * The output of tests must conform to the TAP standard to ensure high testing quality and to capture failures/errors with specific details. The kselftest.h and kselftest_harness.h headers provide wrappers for outputting test results. These wrappers should be used for pass, fail, exit, and skip messages. CI systems can easily parse TAP output messages to detect test results. Contributing new tests (details) ================================ * In your Makefile, use facilities from lib.mk by including it instead of reinventing the wheel. Specify flags and binaries generation flags on need basis before including lib.mk. :: CFLAGS = $(KHDR_INCLUDES) TEST_GEN_PROGS := close_range_test include ../lib.mk * Use TEST_GEN_XXX if such binaries or files are generated during compiling. TEST_PROGS, TEST_GEN_PROGS mean it is the executable tested by default. TEST_GEN_MODS_DIR should be used by tests that require modules to be built before the test starts. The variable will contain the name of the directory containing the modules. TEST_CUSTOM_PROGS should be used by tests that require custom build rules and prevent common build rule use. TEST_PROGS are for test shell scripts. Please ensure shell script has its exec bit set. Otherwise, lib.mk run_tests will generate a warning. TEST_CUSTOM_PROGS and TEST_PROGS will be run by common run_tests. TEST_PROGS_EXTENDED, TEST_GEN_PROGS_EXTENDED mean it is the executable which is not tested by default. TEST_FILES, TEST_GEN_FILES mean it is the file which is used by test. TEST_INCLUDES is similar to TEST_FILES, it lists files which should be included when exporting or installing the tests, with the following differences: * symlinks to files in other directories are preserved * the part of paths below tools/testing/selftests/ is preserved when copying the files to the output directory TEST_INCLUDES is meant to list dependencies located in other directories of the selftests hierarchy. * First use the headers inside the kernel source and/or git repo, and then the system headers. Headers for the kernel release as opposed to headers installed by the distro on the system should be the primary focus to be able to find regressions. Use KHDR_INCLUDES in Makefile to include headers from the kernel source. * If a test needs specific kernel config options enabled, add a config file in the test directory to enable them. e.g: tools/testing/selftests/android/config * Create a .gitignore file inside test directory and add all generated objects in it. * Add new test name in TARGETS in selftests/Makefile:: TARGETS += android * All changes should pass:: kselftest-{all,install,clean,gen_tar} kselftest-{all,install,clean,gen_tar} O=abo_path kselftest-{all,install,clean,gen_tar} O=rel_path make -C tools/testing/selftests {all,install,clean,gen_tar} make -C tools/testing/selftests {all,install,clean,gen_tar} O=abs_path make -C tools/testing/selftests {all,install,clean,gen_tar} O=rel_path Test Module =========== Kselftest tests the kernel from userspace. Sometimes things need testing from within the kernel, one method of doing this is to create a test module. We can tie the module into the kselftest framework by using a shell script test runner. ``kselftest/module.sh`` is designed to facilitate this process. There is also a header file provided to assist writing kernel modules that are for use with kselftest: - ``tools/testing/selftests/kselftest_module.h`` - ``tools/testing/selftests/kselftest/module.sh`` Note that test modules should taint the kernel with TAINT_TEST. This will happen automatically for modules which are in the ``tools/testing/`` directory, or for modules which use the ``kselftest_module.h`` header above. Otherwise, you'll need to add ``MODULE_INFO(test, "Y")`` to your module source. selftests which do not load modules typically should not taint the kernel, but in cases where a non-test module is loaded, TEST_TAINT can be applied from userspace by writing to ``/proc/sys/kernel/tainted``. How to use ---------- Here we show the typical steps to create a test module and tie it into kselftest. We use kselftests for lib/ as an example. 1. Create the test module 2. Create the test script that will run (load/unload) the module e.g. ``tools/testing/selftests/lib/printf.sh`` 3. Add line to config file e.g. ``tools/testing/selftests/lib/config`` 4. Add test script to makefile e.g. ``tools/testing/selftests/lib/Makefile`` 5. Verify it works: .. code-block:: sh # Assumes you have booted a fresh build of this kernel tree cd /path/to/linux/tree make kselftest-merge make modules sudo make modules_install make TARGETS=lib kselftest Example Module -------------- A bare bones test module might look like this: .. code-block:: c // SPDX-License-Identifier: GPL-2.0+ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include "../tools/testing/selftests/kselftest_module.h" KSTM_MODULE_GLOBALS(); /* * Kernel module for testing the foobinator */ static int __init test_function() { ... } static void __init selftest(void) { KSTM_CHECK_ZERO(do_test_case("", 0)); } KSTM_MODULE_LOADERS(test_foo); MODULE_AUTHOR("John Developer <jd@fooman.org>"); MODULE_LICENSE("GPL"); MODULE_INFO(test, "Y"); Example test script ------------------- .. code-block:: sh #!/bin/bash # SPDX-License-Identifier: GPL-2.0+ $(dirname $0)/../kselftest/module.sh "foo" test_foo Test Harness ============ The kselftest_harness.h file contains useful helpers to build tests. The test harness is for userspace testing, for kernel space testing see `Test Module`_ above. The tests from tools/testing/selftests/seccomp/seccomp_bpf.c can be used as example. Example ------- .. kernel-doc:: tools/testing/selftests/kselftest_harness.h :doc: example Helpers ------- .. kernel-doc:: tools/testing/selftests/kselftest_harness.h :functions: TH_LOG TEST TEST_SIGNAL FIXTURE FIXTURE_DATA FIXTURE_SETUP FIXTURE_TEARDOWN TEST_F TEST_HARNESS_MAIN FIXTURE_VARIANT FIXTURE_VARIANT_ADD Operators --------- .. kernel-doc:: tools/testing/selftests/kselftest_harness.h :doc: operators .. kernel-doc:: tools/testing/selftests/kselftest_harness.h :functions: ASSERT_EQ ASSERT_NE ASSERT_LT ASSERT_LE ASSERT_GT ASSERT_GE ASSERT_NULL ASSERT_TRUE ASSERT_NULL ASSERT_TRUE ASSERT_FALSE ASSERT_STREQ ASSERT_STRNE EXPECT_EQ EXPECT_NE EXPECT_LT EXPECT_LE EXPECT_GT EXPECT_GE EXPECT_NULL EXPECT_TRUE EXPECT_FALSE EXPECT_STREQ EXPECT_STRNE |