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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Test module for in-kernel synthetic event creation and generation.
4 *
5 * Copyright (C) 2019 Tom Zanussi <[email protected]>
6 */
7
8#include <linux/module.h>
9#include <linux/trace_events.h>
10
11/*
12 * This module is a simple test of basic functionality for in-kernel
13 * synthetic event creation and generation, the first and second tests
14 * using synth_event_gen_cmd_start() and synth_event_add_field(), the
15 * third uses synth_event_create() to do it all at once with a static
16 * field array.
17 *
18 * Following that are a few examples using the created events to test
19 * various ways of tracing a synthetic event.
20 *
21 * To test, select CONFIG_SYNTH_EVENT_GEN_TEST and build the module.
22 * Then:
23 *
24 * # insmod kernel/trace/synth_event_gen_test.ko
25 * # cat /sys/kernel/tracing/trace
26 *
27 * You should see several events in the trace buffer -
28 * "create_synth_test", "empty_synth_test", and several instances of
29 * "gen_synth_test".
30 *
31 * To remove the events, remove the module:
32 *
33 * # rmmod synth_event_gen_test
34 *
35 */
36
37static struct trace_event_file *create_synth_test;
38static struct trace_event_file *empty_synth_test;
39static struct trace_event_file *gen_synth_test;
40
41/*
42 * Test to make sure we can create a synthetic event, then add more
43 * fields.
44 */
45static int __init test_gen_synth_cmd(void)
46{
47 struct dynevent_cmd cmd;
48 u64 vals[7];
49 char *buf;
50 int ret;
51
52 /* Create a buffer to hold the generated command */
53 buf = kzalloc(MAX_DYNEVENT_CMD_LEN, GFP_KERNEL);
54 if (!buf)
55 return -ENOMEM;
56
57 /* Before generating the command, initialize the cmd object */
58 synth_event_cmd_init(&cmd, buf, MAX_DYNEVENT_CMD_LEN);
59
60 /*
61 * Create the empty gen_synth_test synthetic event with the
62 * first 4 fields.
63 */
64 ret = synth_event_gen_cmd_start(&cmd, "gen_synth_test", THIS_MODULE,
65 "pid_t", "next_pid_field",
66 "char[16]", "next_comm_field",
67 "u64", "ts_ns",
68 "u64", "ts_ms");
69 if (ret)
70 goto free;
71
72 /* Use synth_event_add_field to add the rest of the fields */
73
74 ret = synth_event_add_field(&cmd, "unsigned int", "cpu");
75 if (ret)
76 goto free;
77
78 ret = synth_event_add_field(&cmd, "char[64]", "my_string_field");
79 if (ret)
80 goto free;
81
82 ret = synth_event_add_field(&cmd, "int", "my_int_field");
83 if (ret)
84 goto free;
85
86 ret = synth_event_gen_cmd_end(&cmd);
87 if (ret)
88 goto free;
89
90 /*
91 * Now get the gen_synth_test event file. We need to prevent
92 * the instance and event from disappearing from underneath
93 * us, which trace_get_event_file() does (though in this case
94 * we're using the top-level instance which never goes away).
95 */
96 gen_synth_test = trace_get_event_file(NULL, "synthetic",
97 "gen_synth_test");
98 if (IS_ERR(gen_synth_test)) {
99 ret = PTR_ERR(gen_synth_test);
100 goto delete;
101 }
102
103 /* Enable the event or you won't see anything */
104 ret = trace_array_set_clr_event(gen_synth_test->tr,
105 "synthetic", "gen_synth_test", true);
106 if (ret) {
107 trace_put_event_file(gen_synth_test);
108 goto delete;
109 }
110
111 /* Create some bogus values just for testing */
112
113 vals[0] = 777; /* next_pid_field */
114 vals[1] = (u64)(long)"hula hoops"; /* next_comm_field */
115 vals[2] = 1000000; /* ts_ns */
116 vals[3] = 1000; /* ts_ms */
117 vals[4] = raw_smp_processor_id(); /* cpu */
118 vals[5] = (u64)(long)"thneed"; /* my_string_field */
119 vals[6] = 598; /* my_int_field */
120
121 /* Now generate a gen_synth_test event */
122 ret = synth_event_trace_array(gen_synth_test, vals, ARRAY_SIZE(vals));
123 free:
124 kfree(buf);
125 return ret;
126 delete:
127 /* We got an error after creating the event, delete it */
128 synth_event_delete("gen_synth_test");
129 goto free;
130}
131
132/*
133 * Test to make sure we can create an initially empty synthetic event,
134 * then add all the fields.
135 */
136static int __init test_empty_synth_event(void)
137{
138 struct dynevent_cmd cmd;
139 u64 vals[7];
140 char *buf;
141 int ret;
142
143 /* Create a buffer to hold the generated command */
144 buf = kzalloc(MAX_DYNEVENT_CMD_LEN, GFP_KERNEL);
145 if (!buf)
146 return -ENOMEM;
147
148 /* Before generating the command, initialize the cmd object */
149 synth_event_cmd_init(&cmd, buf, MAX_DYNEVENT_CMD_LEN);
150
151 /*
152 * Create the empty_synth_test synthetic event with no fields.
153 */
154 ret = synth_event_gen_cmd_start(&cmd, "empty_synth_test", THIS_MODULE);
155 if (ret)
156 goto free;
157
158 /* Use synth_event_add_field to add all of the fields */
159
160 ret = synth_event_add_field(&cmd, "pid_t", "next_pid_field");
161 if (ret)
162 goto free;
163
164 ret = synth_event_add_field(&cmd, "char[16]", "next_comm_field");
165 if (ret)
166 goto free;
167
168 ret = synth_event_add_field(&cmd, "u64", "ts_ns");
169 if (ret)
170 goto free;
171
172 ret = synth_event_add_field(&cmd, "u64", "ts_ms");
173 if (ret)
174 goto free;
175
176 ret = synth_event_add_field(&cmd, "unsigned int", "cpu");
177 if (ret)
178 goto free;
179
180 ret = synth_event_add_field(&cmd, "char[64]", "my_string_field");
181 if (ret)
182 goto free;
183
184 ret = synth_event_add_field(&cmd, "int", "my_int_field");
185 if (ret)
186 goto free;
187
188 /* All fields have been added, close and register the synth event */
189
190 ret = synth_event_gen_cmd_end(&cmd);
191 if (ret)
192 goto free;
193
194 /*
195 * Now get the empty_synth_test event file. We need to
196 * prevent the instance and event from disappearing from
197 * underneath us, which trace_get_event_file() does (though in
198 * this case we're using the top-level instance which never
199 * goes away).
200 */
201 empty_synth_test = trace_get_event_file(NULL, "synthetic",
202 "empty_synth_test");
203 if (IS_ERR(empty_synth_test)) {
204 ret = PTR_ERR(empty_synth_test);
205 goto delete;
206 }
207
208 /* Enable the event or you won't see anything */
209 ret = trace_array_set_clr_event(empty_synth_test->tr,
210 "synthetic", "empty_synth_test", true);
211 if (ret) {
212 trace_put_event_file(empty_synth_test);
213 goto delete;
214 }
215
216 /* Create some bogus values just for testing */
217
218 vals[0] = 777; /* next_pid_field */
219 vals[1] = (u64)(long)"tiddlywinks"; /* next_comm_field */
220 vals[2] = 1000000; /* ts_ns */
221 vals[3] = 1000; /* ts_ms */
222 vals[4] = raw_smp_processor_id(); /* cpu */
223 vals[5] = (u64)(long)"thneed_2.0"; /* my_string_field */
224 vals[6] = 399; /* my_int_field */
225
226 /* Now trace an empty_synth_test event */
227 ret = synth_event_trace_array(empty_synth_test, vals, ARRAY_SIZE(vals));
228 free:
229 kfree(buf);
230 return ret;
231 delete:
232 /* We got an error after creating the event, delete it */
233 synth_event_delete("empty_synth_test");
234 goto free;
235}
236
237static struct synth_field_desc create_synth_test_fields[] = {
238 { .type = "pid_t", .name = "next_pid_field" },
239 { .type = "char[16]", .name = "next_comm_field" },
240 { .type = "u64", .name = "ts_ns" },
241 { .type = "char[]", .name = "dynstring_field_1" },
242 { .type = "u64", .name = "ts_ms" },
243 { .type = "unsigned int", .name = "cpu" },
244 { .type = "char[64]", .name = "my_string_field" },
245 { .type = "char[]", .name = "dynstring_field_2" },
246 { .type = "int", .name = "my_int_field" },
247};
248
249/*
250 * Test synthetic event creation all at once from array of field
251 * descriptors.
252 */
253static int __init test_create_synth_event(void)
254{
255 u64 vals[9];
256 int ret;
257
258 /* Create the create_synth_test event with the fields above */
259 ret = synth_event_create("create_synth_test",
260 create_synth_test_fields,
261 ARRAY_SIZE(create_synth_test_fields),
262 THIS_MODULE);
263 if (ret)
264 goto out;
265
266 /*
267 * Now get the create_synth_test event file. We need to
268 * prevent the instance and event from disappearing from
269 * underneath us, which trace_get_event_file() does (though in
270 * this case we're using the top-level instance which never
271 * goes away).
272 */
273 create_synth_test = trace_get_event_file(NULL, "synthetic",
274 "create_synth_test");
275 if (IS_ERR(create_synth_test)) {
276 ret = PTR_ERR(create_synth_test);
277 goto delete;
278 }
279
280 /* Enable the event or you won't see anything */
281 ret = trace_array_set_clr_event(create_synth_test->tr,
282 "synthetic", "create_synth_test", true);
283 if (ret) {
284 trace_put_event_file(create_synth_test);
285 goto delete;
286 }
287
288 /* Create some bogus values just for testing */
289
290 vals[0] = 777; /* next_pid_field */
291 vals[1] = (u64)(long)"tiddlywinks"; /* next_comm_field */
292 vals[2] = 1000000; /* ts_ns */
293 vals[3] = (u64)(long)"xrayspecs"; /* dynstring_field_1 */
294 vals[4] = 1000; /* ts_ms */
295 vals[5] = raw_smp_processor_id(); /* cpu */
296 vals[6] = (u64)(long)"thneed"; /* my_string_field */
297 vals[7] = (u64)(long)"kerplunk"; /* dynstring_field_2 */
298 vals[8] = 398; /* my_int_field */
299
300 /* Now generate a create_synth_test event */
301 ret = synth_event_trace_array(create_synth_test, vals, ARRAY_SIZE(vals));
302 out:
303 return ret;
304 delete:
305 /* We got an error after creating the event, delete it */
306 synth_event_delete("create_synth_test");
307
308 goto out;
309}
310
311/*
312 * Test tracing a synthetic event by reserving trace buffer space,
313 * then filling in fields one after another.
314 */
315static int __init test_add_next_synth_val(void)
316{
317 struct synth_event_trace_state trace_state;
318 int ret;
319
320 /* Start by reserving space in the trace buffer */
321 ret = synth_event_trace_start(gen_synth_test, &trace_state);
322 if (ret)
323 return ret;
324
325 /* Write some bogus values into the trace buffer, one after another */
326
327 /* next_pid_field */
328 ret = synth_event_add_next_val(777, &trace_state);
329 if (ret)
330 goto out;
331
332 /* next_comm_field */
333 ret = synth_event_add_next_val((u64)(long)"slinky", &trace_state);
334 if (ret)
335 goto out;
336
337 /* ts_ns */
338 ret = synth_event_add_next_val(1000000, &trace_state);
339 if (ret)
340 goto out;
341
342 /* ts_ms */
343 ret = synth_event_add_next_val(1000, &trace_state);
344 if (ret)
345 goto out;
346
347 /* cpu */
348 ret = synth_event_add_next_val(raw_smp_processor_id(), &trace_state);
349 if (ret)
350 goto out;
351
352 /* my_string_field */
353 ret = synth_event_add_next_val((u64)(long)"thneed_2.01", &trace_state);
354 if (ret)
355 goto out;
356
357 /* my_int_field */
358 ret = synth_event_add_next_val(395, &trace_state);
359 out:
360 /* Finally, commit the event */
361 ret = synth_event_trace_end(&trace_state);
362
363 return ret;
364}
365
366/*
367 * Test tracing a synthetic event by reserving trace buffer space,
368 * then filling in fields using field names, which can be done in any
369 * order.
370 */
371static int __init test_add_synth_val(void)
372{
373 struct synth_event_trace_state trace_state;
374 int ret;
375
376 /* Start by reserving space in the trace buffer */
377 ret = synth_event_trace_start(gen_synth_test, &trace_state);
378 if (ret)
379 return ret;
380
381 /* Write some bogus values into the trace buffer, using field names */
382
383 ret = synth_event_add_val("ts_ns", 1000000, &trace_state);
384 if (ret)
385 goto out;
386
387 ret = synth_event_add_val("ts_ms", 1000, &trace_state);
388 if (ret)
389 goto out;
390
391 ret = synth_event_add_val("cpu", raw_smp_processor_id(), &trace_state);
392 if (ret)
393 goto out;
394
395 ret = synth_event_add_val("next_pid_field", 777, &trace_state);
396 if (ret)
397 goto out;
398
399 ret = synth_event_add_val("next_comm_field", (u64)(long)"silly putty",
400 &trace_state);
401 if (ret)
402 goto out;
403
404 ret = synth_event_add_val("my_string_field", (u64)(long)"thneed_9",
405 &trace_state);
406 if (ret)
407 goto out;
408
409 ret = synth_event_add_val("my_int_field", 3999, &trace_state);
410 out:
411 /* Finally, commit the event */
412 ret = synth_event_trace_end(&trace_state);
413
414 return ret;
415}
416
417/*
418 * Test tracing a synthetic event all at once from array of values.
419 */
420static int __init test_trace_synth_event(void)
421{
422 int ret;
423
424 /* Trace some bogus values just for testing */
425 ret = synth_event_trace(create_synth_test, 9, /* number of values */
426 (u64)444, /* next_pid_field */
427 (u64)(long)"clackers", /* next_comm_field */
428 (u64)1000000, /* ts_ns */
429 (u64)(long)"viewmaster",/* dynstring_field_1 */
430 (u64)1000, /* ts_ms */
431 (u64)raw_smp_processor_id(), /* cpu */
432 (u64)(long)"Thneed", /* my_string_field */
433 (u64)(long)"yoyos", /* dynstring_field_2 */
434 (u64)999); /* my_int_field */
435 return ret;
436}
437
438static int __init synth_event_gen_test_init(void)
439{
440 int ret;
441
442 ret = test_gen_synth_cmd();
443 if (ret)
444 return ret;
445
446 ret = test_empty_synth_event();
447 if (ret) {
448 WARN_ON(trace_array_set_clr_event(gen_synth_test->tr,
449 "synthetic",
450 "gen_synth_test", false));
451 trace_put_event_file(gen_synth_test);
452 WARN_ON(synth_event_delete("gen_synth_test"));
453 goto out;
454 }
455
456 ret = test_create_synth_event();
457 if (ret) {
458 WARN_ON(trace_array_set_clr_event(gen_synth_test->tr,
459 "synthetic",
460 "gen_synth_test", false));
461 trace_put_event_file(gen_synth_test);
462 WARN_ON(synth_event_delete("gen_synth_test"));
463
464 WARN_ON(trace_array_set_clr_event(empty_synth_test->tr,
465 "synthetic",
466 "empty_synth_test", false));
467 trace_put_event_file(empty_synth_test);
468 WARN_ON(synth_event_delete("empty_synth_test"));
469 goto out;
470 }
471
472 ret = test_add_next_synth_val();
473 WARN_ON(ret);
474
475 ret = test_add_synth_val();
476 WARN_ON(ret);
477
478 ret = test_trace_synth_event();
479 WARN_ON(ret);
480
481 /* Disable when done */
482 trace_array_set_clr_event(gen_synth_test->tr,
483 "synthetic",
484 "gen_synth_test", false);
485 trace_array_set_clr_event(empty_synth_test->tr,
486 "synthetic",
487 "empty_synth_test", false);
488 trace_array_set_clr_event(create_synth_test->tr,
489 "synthetic",
490 "create_synth_test", false);
491 out:
492 return ret;
493}
494
495static void __exit synth_event_gen_test_exit(void)
496{
497 /* Disable the event or you can't remove it */
498 WARN_ON(trace_array_set_clr_event(gen_synth_test->tr,
499 "synthetic",
500 "gen_synth_test", false));
501
502 /* Now give the file and instance back */
503 trace_put_event_file(gen_synth_test);
504
505 /* Now unregister and free the synthetic event */
506 WARN_ON(synth_event_delete("gen_synth_test"));
507
508 /* Disable the event or you can't remove it */
509 WARN_ON(trace_array_set_clr_event(empty_synth_test->tr,
510 "synthetic",
511 "empty_synth_test", false));
512
513 /* Now give the file and instance back */
514 trace_put_event_file(empty_synth_test);
515
516 /* Now unregister and free the synthetic event */
517 WARN_ON(synth_event_delete("empty_synth_test"));
518
519 /* Disable the event or you can't remove it */
520 WARN_ON(trace_array_set_clr_event(create_synth_test->tr,
521 "synthetic",
522 "create_synth_test", false));
523
524 /* Now give the file and instance back */
525 trace_put_event_file(create_synth_test);
526
527 /* Now unregister and free the synthetic event */
528 WARN_ON(synth_event_delete("create_synth_test"));
529}
530
531module_init(synth_event_gen_test_init)
532module_exit(synth_event_gen_test_exit)
533
534MODULE_AUTHOR("Tom Zanussi");
535MODULE_DESCRIPTION("synthetic event generation test");
536MODULE_LICENSE("GPL v2");