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