Commit | Line | Data |
---|---|---|
d58d1454 MD |
1 | /* |
2 | * lttng-context-perf-counters.c | |
3 | * | |
4 | * LTTng UST performance monitoring counters (perf-counters) integration. | |
5 | * | |
6 | * Copyright (C) 2009-2014 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | |
7 | * | |
8 | * This library is free software; you can redistribute it and/or | |
9 | * modify it under the terms of the GNU Lesser General Public | |
10 | * License as published by the Free Software Foundation; only | |
11 | * version 2.1 of the License. | |
12 | * | |
13 | * This library is distributed in the hope that it will be useful, | |
14 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
16 | * Lesser General Public License for more details. | |
17 | * | |
18 | * You should have received a copy of the GNU Lesser General Public | |
19 | * License along with this library; if not, write to the Free Software | |
20 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA | |
21 | */ | |
22 | ||
23 | #include <sys/types.h> | |
24 | #include <unistd.h> | |
25 | #include <string.h> | |
26 | #include <stdlib.h> | |
27 | #include <stdio.h> | |
649fb6b3 | 28 | #include <stdbool.h> |
d58d1454 MD |
29 | #include <sys/mman.h> |
30 | #include <sys/syscall.h> | |
31 | #include <linux/perf_event.h> | |
32 | #include <lttng/ust-events.h> | |
33 | #include <lttng/ust-tracer.h> | |
34 | #include <lttng/ringbuffer-config.h> | |
35 | #include <urcu/system.h> | |
36 | #include <urcu/arch.h> | |
37 | #include <urcu/rculist.h> | |
38 | #include <helper.h> | |
39 | #include <urcu/ref.h> | |
40 | #include <usterr-signal-safe.h> | |
41 | #include <signal.h> | |
42 | #include "lttng-tracer-core.h" | |
43 | ||
44 | /* | |
45 | * We use a global perf counter key and iterate on per-thread RCU lists | |
46 | * of fields in the fast path, even though this is not strictly speaking | |
47 | * what would provide the best fast-path complexity, to ensure teardown | |
48 | * of sessions vs thread exit is handled racelessly. | |
49 | * | |
50 | * Updates and traversals of thread_list are protected by UST lock. | |
51 | * Updates to rcu_field_list are protected by UST lock. | |
52 | */ | |
53 | ||
54 | struct lttng_perf_counter_thread_field { | |
55 | struct lttng_perf_counter_field *field; /* Back reference */ | |
56 | struct perf_event_mmap_page *pc; | |
57 | struct cds_list_head thread_field_node; /* Per-field list of thread fields (node) */ | |
58 | struct cds_list_head rcu_field_node; /* RCU per-thread list of fields (node) */ | |
b9389e6e | 59 | int fd; /* Perf FD */ |
d58d1454 MD |
60 | }; |
61 | ||
62 | struct lttng_perf_counter_thread { | |
63 | struct cds_list_head rcu_field_list; /* RCU per-thread list of fields */ | |
64 | }; | |
65 | ||
66 | struct lttng_perf_counter_field { | |
67 | struct perf_event_attr attr; | |
68 | struct cds_list_head thread_field_list; /* Per-field list of thread fields */ | |
69 | }; | |
70 | ||
71 | static pthread_key_t perf_counter_key; | |
72 | ||
73 | static | |
53569322 | 74 | size_t perf_counter_get_size(struct lttng_ctx_field *field, size_t offset) |
d58d1454 MD |
75 | { |
76 | size_t size = 0; | |
77 | ||
78 | size += lib_ring_buffer_align(offset, lttng_alignof(uint64_t)); | |
79 | size += sizeof(uint64_t); | |
80 | return size; | |
81 | } | |
82 | ||
83 | #if defined(__x86_64__) || defined(__i386__) | |
84 | ||
85 | static | |
86 | uint64_t rdpmc(unsigned int counter) | |
87 | { | |
88 | unsigned int low, high; | |
89 | ||
90 | asm volatile("rdpmc" : "=a" (low), "=d" (high) : "c" (counter)); | |
91 | ||
92 | return low | ((uint64_t) high) << 32; | |
93 | } | |
94 | ||
b9389e6e JD |
95 | static bool arch_perf_use_read(void) |
96 | { | |
97 | return false; | |
98 | } | |
99 | ||
d58d1454 | 100 | static |
d286ad50 JD |
101 | uint64_t read_perf_counter( |
102 | struct lttng_perf_counter_thread_field *thread_field) | |
d58d1454 MD |
103 | { |
104 | uint32_t seq, idx; | |
105 | uint64_t count; | |
d286ad50 | 106 | struct perf_event_mmap_page *pc = thread_field->pc; |
d58d1454 MD |
107 | |
108 | if (caa_unlikely(!pc)) | |
109 | return 0; | |
110 | ||
111 | do { | |
112 | seq = CMM_LOAD_SHARED(pc->lock); | |
113 | cmm_barrier(); | |
114 | ||
115 | idx = pc->index; | |
116 | if (idx) | |
117 | count = pc->offset + rdpmc(idx - 1); | |
118 | else | |
119 | count = 0; | |
120 | ||
121 | cmm_barrier(); | |
122 | } while (CMM_LOAD_SHARED(pc->lock) != seq); | |
123 | ||
124 | return count; | |
125 | } | |
126 | ||
d286ad50 JD |
127 | #elif defined (__ARM_ARCH_7A__) |
128 | ||
129 | static bool arch_perf_use_read(void) | |
130 | { | |
131 | return true; | |
132 | } | |
133 | ||
134 | static | |
135 | uint64_t read_perf_counter( | |
136 | struct lttng_perf_counter_thread_field *thread_field) | |
137 | { | |
138 | uint64_t count; | |
139 | ||
140 | if (caa_unlikely(thread_field->fd < 0)) | |
141 | return 0; | |
142 | ||
143 | if (caa_unlikely(read(thread_field->fd, &count, sizeof(count)) | |
144 | < sizeof(count))) | |
145 | return 0; | |
146 | ||
147 | return count; | |
148 | } | |
149 | ||
150 | #else /* defined(__x86_64__) || defined(__i386__) || defined(__ARM_ARCH_7A__) */ | |
151 | ||
152 | #error "Perf event counters are only supported on x86 and ARMv7 so far." | |
153 | ||
154 | #endif /* #else defined(__x86_64__) || defined(__i386__) || defined(__ARM_ARCH_7A__) */ | |
155 | ||
d58d1454 MD |
156 | static |
157 | int sys_perf_event_open(struct perf_event_attr *attr, | |
158 | pid_t pid, int cpu, int group_fd, | |
159 | unsigned long flags) | |
160 | { | |
161 | return syscall(SYS_perf_event_open, attr, pid, cpu, | |
162 | group_fd, flags); | |
163 | } | |
164 | ||
165 | static | |
b9389e6e | 166 | int open_perf_fd(struct perf_event_attr *attr) |
d58d1454 | 167 | { |
b9389e6e | 168 | int fd; |
d58d1454 MD |
169 | |
170 | fd = sys_perf_event_open(attr, 0, -1, -1, 0); | |
171 | if (fd < 0) | |
b9389e6e JD |
172 | return -1; |
173 | ||
174 | return fd; | |
175 | } | |
176 | ||
d286ad50 JD |
177 | static |
178 | void close_perf_fd(int fd) | |
179 | { | |
180 | int ret; | |
181 | ||
182 | if (fd < 0) | |
183 | return; | |
184 | ||
185 | ret = close(fd); | |
186 | if (ret) { | |
187 | perror("Error closing LTTng-UST perf memory mapping FD"); | |
188 | } | |
189 | } | |
190 | ||
b9389e6e JD |
191 | static |
192 | struct perf_event_mmap_page *setup_perf( | |
193 | struct lttng_perf_counter_thread_field *thread_field) | |
194 | { | |
195 | void *perf_addr; | |
d58d1454 MD |
196 | |
197 | perf_addr = mmap(NULL, sizeof(struct perf_event_mmap_page), | |
b9389e6e | 198 | PROT_READ, MAP_SHARED, thread_field->fd, 0); |
d58d1454 | 199 | if (perf_addr == MAP_FAILED) |
b9389e6e JD |
200 | perf_addr = NULL; |
201 | ||
202 | if (!arch_perf_use_read()) { | |
203 | close_perf_fd(thread_field->fd); | |
204 | thread_field->fd = -1; | |
6c2125af | 205 | } |
b9389e6e | 206 | |
d58d1454 MD |
207 | return perf_addr; |
208 | } | |
209 | ||
210 | static | |
211 | void unmap_perf_page(struct perf_event_mmap_page *pc) | |
212 | { | |
213 | int ret; | |
214 | ||
215 | if (!pc) | |
216 | return; | |
217 | ret = munmap(pc, sizeof(struct perf_event_mmap_page)); | |
218 | if (ret < 0) { | |
219 | PERROR("Error in munmap"); | |
220 | abort(); | |
221 | } | |
222 | } | |
223 | ||
224 | static | |
225 | struct lttng_perf_counter_thread *alloc_perf_counter_thread(void) | |
226 | { | |
227 | struct lttng_perf_counter_thread *perf_thread; | |
228 | sigset_t newmask, oldmask; | |
229 | int ret; | |
230 | ||
231 | ret = sigfillset(&newmask); | |
232 | if (ret) | |
233 | abort(); | |
234 | ret = pthread_sigmask(SIG_BLOCK, &newmask, &oldmask); | |
235 | if (ret) | |
236 | abort(); | |
237 | /* Check again with signals disabled */ | |
238 | perf_thread = pthread_getspecific(perf_counter_key); | |
239 | if (perf_thread) | |
240 | goto skip; | |
241 | perf_thread = zmalloc(sizeof(*perf_thread)); | |
242 | if (!perf_thread) | |
243 | abort(); | |
244 | CDS_INIT_LIST_HEAD(&perf_thread->rcu_field_list); | |
245 | ret = pthread_setspecific(perf_counter_key, perf_thread); | |
246 | if (ret) | |
247 | abort(); | |
248 | skip: | |
249 | ret = pthread_sigmask(SIG_SETMASK, &oldmask, NULL); | |
250 | if (ret) | |
251 | abort(); | |
252 | return perf_thread; | |
253 | } | |
254 | ||
255 | static | |
256 | struct lttng_perf_counter_thread_field * | |
257 | add_thread_field(struct lttng_perf_counter_field *perf_field, | |
258 | struct lttng_perf_counter_thread *perf_thread) | |
259 | { | |
260 | struct lttng_perf_counter_thread_field *thread_field; | |
261 | sigset_t newmask, oldmask; | |
262 | int ret; | |
263 | ||
264 | ret = sigfillset(&newmask); | |
265 | if (ret) | |
266 | abort(); | |
267 | ret = pthread_sigmask(SIG_BLOCK, &newmask, &oldmask); | |
268 | if (ret) | |
269 | abort(); | |
270 | /* Check again with signals disabled */ | |
271 | cds_list_for_each_entry_rcu(thread_field, &perf_thread->rcu_field_list, | |
272 | rcu_field_node) { | |
273 | if (thread_field->field == perf_field) | |
274 | goto skip; | |
275 | } | |
276 | thread_field = zmalloc(sizeof(*thread_field)); | |
277 | if (!thread_field) | |
278 | abort(); | |
279 | thread_field->field = perf_field; | |
b9389e6e JD |
280 | thread_field->fd = open_perf_fd(&perf_field->attr); |
281 | if (thread_field->fd >= 0) | |
282 | thread_field->pc = setup_perf(thread_field); | |
283 | /* | |
284 | * Note: thread_field->pc can be NULL if setup_perf() fails. | |
285 | * Also, thread_field->fd can be -1 if open_perf_fd() fails. | |
286 | */ | |
d58d1454 MD |
287 | ust_lock_nocheck(); |
288 | cds_list_add_rcu(&thread_field->rcu_field_node, | |
289 | &perf_thread->rcu_field_list); | |
290 | cds_list_add(&thread_field->thread_field_node, | |
291 | &perf_field->thread_field_list); | |
292 | ust_unlock(); | |
293 | skip: | |
294 | ret = pthread_sigmask(SIG_SETMASK, &oldmask, NULL); | |
295 | if (ret) | |
296 | abort(); | |
297 | return thread_field; | |
298 | } | |
299 | ||
300 | static | |
301 | struct lttng_perf_counter_thread_field * | |
302 | get_thread_field(struct lttng_perf_counter_field *field) | |
303 | { | |
304 | struct lttng_perf_counter_thread *perf_thread; | |
305 | struct lttng_perf_counter_thread_field *thread_field; | |
306 | ||
307 | perf_thread = pthread_getspecific(perf_counter_key); | |
308 | if (!perf_thread) | |
309 | perf_thread = alloc_perf_counter_thread(); | |
310 | cds_list_for_each_entry_rcu(thread_field, &perf_thread->rcu_field_list, | |
311 | rcu_field_node) { | |
312 | if (thread_field->field == field) | |
313 | return thread_field; | |
314 | } | |
315 | /* perf_counter_thread_field not found, need to add one */ | |
316 | return add_thread_field(field, perf_thread); | |
317 | } | |
318 | ||
319 | static | |
320 | uint64_t wrapper_perf_counter_read(struct lttng_ctx_field *field) | |
321 | { | |
322 | struct lttng_perf_counter_field *perf_field; | |
323 | struct lttng_perf_counter_thread_field *perf_thread_field; | |
324 | ||
325 | perf_field = field->u.perf_counter; | |
326 | perf_thread_field = get_thread_field(perf_field); | |
d286ad50 | 327 | return read_perf_counter(perf_thread_field); |
d58d1454 MD |
328 | } |
329 | ||
330 | static | |
331 | void perf_counter_record(struct lttng_ctx_field *field, | |
332 | struct lttng_ust_lib_ring_buffer_ctx *ctx, | |
333 | struct lttng_channel *chan) | |
334 | { | |
335 | uint64_t value; | |
336 | ||
337 | value = wrapper_perf_counter_read(field); | |
338 | lib_ring_buffer_align_ctx(ctx, lttng_alignof(value)); | |
339 | chan->ops->event_write(ctx, &value, sizeof(value)); | |
340 | } | |
341 | ||
342 | static | |
343 | void perf_counter_get_value(struct lttng_ctx_field *field, | |
53569322 | 344 | struct lttng_ctx_value *value) |
d58d1454 MD |
345 | { |
346 | uint64_t v; | |
347 | ||
348 | v = wrapper_perf_counter_read(field); | |
53569322 | 349 | value->u.s64 = v; |
d58d1454 MD |
350 | } |
351 | ||
352 | /* Called with UST lock held */ | |
353 | static | |
354 | void lttng_destroy_perf_thread_field( | |
355 | struct lttng_perf_counter_thread_field *thread_field) | |
356 | { | |
b9389e6e | 357 | close_perf_fd(thread_field->fd); |
d58d1454 MD |
358 | unmap_perf_page(thread_field->pc); |
359 | cds_list_del_rcu(&thread_field->rcu_field_node); | |
360 | cds_list_del(&thread_field->thread_field_node); | |
361 | free(thread_field); | |
362 | } | |
363 | ||
364 | static | |
365 | void lttng_destroy_perf_thread_key(void *_key) | |
366 | { | |
367 | struct lttng_perf_counter_thread *perf_thread = _key; | |
368 | struct lttng_perf_counter_thread_field *pos, *p; | |
369 | ||
370 | ust_lock_nocheck(); | |
371 | cds_list_for_each_entry_safe(pos, p, &perf_thread->rcu_field_list, | |
372 | rcu_field_node) | |
373 | lttng_destroy_perf_thread_field(pos); | |
374 | ust_unlock(); | |
375 | free(perf_thread); | |
376 | } | |
377 | ||
378 | /* Called with UST lock held */ | |
379 | static | |
380 | void lttng_destroy_perf_counter_field(struct lttng_ctx_field *field) | |
381 | { | |
382 | struct lttng_perf_counter_field *perf_field; | |
383 | struct lttng_perf_counter_thread_field *pos, *p; | |
384 | ||
385 | free((char *) field->event_field.name); | |
386 | perf_field = field->u.perf_counter; | |
387 | /* | |
388 | * This put is performed when no threads can concurrently | |
389 | * perform a "get" concurrently, thanks to urcu-bp grace | |
390 | * period. | |
391 | */ | |
392 | cds_list_for_each_entry_safe(pos, p, &perf_field->thread_field_list, | |
393 | thread_field_node) | |
394 | lttng_destroy_perf_thread_field(pos); | |
395 | free(perf_field); | |
396 | } | |
397 | ||
d286ad50 JD |
398 | #ifdef __ARM_ARCH_7A__ |
399 | ||
400 | static | |
401 | int perf_get_exclude_kernel(void) | |
402 | { | |
403 | return 0; | |
404 | } | |
405 | ||
406 | #else /* __ARM_ARCH_7A__ */ | |
407 | ||
408 | static | |
409 | int perf_get_exclude_kernel(void) | |
410 | { | |
411 | return 1; | |
412 | } | |
413 | ||
414 | #endif /* __ARM_ARCH_7A__ */ | |
415 | ||
d58d1454 MD |
416 | /* Called with UST lock held */ |
417 | int lttng_add_perf_counter_to_ctx(uint32_t type, | |
418 | uint64_t config, | |
419 | const char *name, | |
420 | struct lttng_ctx **ctx) | |
421 | { | |
422 | struct lttng_ctx_field *field; | |
423 | struct lttng_perf_counter_field *perf_field; | |
d58d1454 MD |
424 | char *name_alloc; |
425 | int ret; | |
426 | ||
427 | name_alloc = strdup(name); | |
428 | if (!name_alloc) { | |
429 | ret = -ENOMEM; | |
430 | goto name_alloc_error; | |
431 | } | |
432 | perf_field = zmalloc(sizeof(*perf_field)); | |
433 | if (!perf_field) { | |
434 | ret = -ENOMEM; | |
435 | goto perf_field_alloc_error; | |
436 | } | |
437 | field = lttng_append_context(ctx); | |
438 | if (!field) { | |
439 | ret = -ENOMEM; | |
440 | goto append_context_error; | |
441 | } | |
442 | if (lttng_find_context(*ctx, name_alloc)) { | |
443 | ret = -EEXIST; | |
444 | goto find_error; | |
445 | } | |
446 | ||
447 | field->destroy = lttng_destroy_perf_counter_field; | |
448 | ||
449 | field->event_field.name = name_alloc; | |
450 | field->event_field.type.atype = atype_integer; | |
451 | field->event_field.type.u.basic.integer.size = | |
452 | sizeof(uint64_t) * CHAR_BIT; | |
453 | field->event_field.type.u.basic.integer.alignment = | |
454 | lttng_alignof(uint64_t) * CHAR_BIT; | |
455 | field->event_field.type.u.basic.integer.signedness = | |
456 | lttng_is_signed_type(uint64_t); | |
457 | field->event_field.type.u.basic.integer.reverse_byte_order = 0; | |
458 | field->event_field.type.u.basic.integer.base = 10; | |
459 | field->event_field.type.u.basic.integer.encoding = lttng_encode_none; | |
460 | field->get_size = perf_counter_get_size; | |
461 | field->record = perf_counter_record; | |
462 | field->get_value = perf_counter_get_value; | |
463 | ||
464 | perf_field->attr.type = type; | |
465 | perf_field->attr.config = config; | |
d286ad50 | 466 | perf_field->attr.exclude_kernel = perf_get_exclude_kernel(); |
d58d1454 MD |
467 | CDS_INIT_LIST_HEAD(&perf_field->thread_field_list); |
468 | field->u.perf_counter = perf_field; | |
469 | ||
470 | /* Ensure that this perf counter can be used in this process. */ | |
b9389e6e JD |
471 | ret = open_perf_fd(&perf_field->attr); |
472 | if (ret < 0) { | |
d58d1454 MD |
473 | ret = -ENODEV; |
474 | goto setup_error; | |
475 | } | |
b9389e6e | 476 | close_perf_fd(ret); |
d58d1454 MD |
477 | |
478 | /* | |
479 | * Contexts can only be added before tracing is started, so we | |
480 | * don't have to synchronize against concurrent threads using | |
481 | * the field here. | |
482 | */ | |
483 | ||
b2cc986a | 484 | lttng_context_update(*ctx); |
d58d1454 MD |
485 | return 0; |
486 | ||
487 | setup_error: | |
488 | find_error: | |
489 | lttng_remove_context_field(ctx, field); | |
490 | append_context_error: | |
491 | free(perf_field); | |
492 | perf_field_alloc_error: | |
493 | free(name_alloc); | |
494 | name_alloc_error: | |
495 | return ret; | |
496 | } | |
497 | ||
498 | int lttng_perf_counter_init(void) | |
499 | { | |
500 | int ret; | |
501 | ||
502 | ret = pthread_key_create(&perf_counter_key, | |
503 | lttng_destroy_perf_thread_key); | |
504 | if (ret) | |
505 | ret = -ret; | |
506 | return ret; | |
507 | } | |
508 | ||
509 | void lttng_perf_counter_exit(void) | |
510 | { | |
511 | int ret; | |
512 | ||
513 | ret = pthread_key_delete(perf_counter_key); | |
514 | if (ret) { | |
515 | errno = ret; | |
516 | PERROR("Error in pthread_key_delete"); | |
517 | } | |
518 | } |