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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> | |
28 | #include <sys/mman.h> | |
29 | #include <sys/syscall.h> | |
30 | #include <linux/perf_event.h> | |
31 | #include <lttng/ust-events.h> | |
32 | #include <lttng/ust-tracer.h> | |
33 | #include <lttng/ringbuffer-config.h> | |
34 | #include <urcu/system.h> | |
35 | #include <urcu/arch.h> | |
36 | #include <urcu/rculist.h> | |
37 | #include <helper.h> | |
38 | #include <urcu/ref.h> | |
39 | #include <usterr-signal-safe.h> | |
40 | #include <signal.h> | |
41 | #include "lttng-tracer-core.h" | |
42 | ||
43 | /* | |
44 | * We use a global perf counter key and iterate on per-thread RCU lists | |
45 | * of fields in the fast path, even though this is not strictly speaking | |
46 | * what would provide the best fast-path complexity, to ensure teardown | |
47 | * of sessions vs thread exit is handled racelessly. | |
48 | * | |
49 | * Updates and traversals of thread_list are protected by UST lock. | |
50 | * Updates to rcu_field_list are protected by UST lock. | |
51 | */ | |
52 | ||
53 | struct lttng_perf_counter_thread_field { | |
54 | struct lttng_perf_counter_field *field; /* Back reference */ | |
55 | struct perf_event_mmap_page *pc; | |
56 | struct cds_list_head thread_field_node; /* Per-field list of thread fields (node) */ | |
57 | struct cds_list_head rcu_field_node; /* RCU per-thread list of fields (node) */ | |
58 | }; | |
59 | ||
60 | struct lttng_perf_counter_thread { | |
61 | struct cds_list_head rcu_field_list; /* RCU per-thread list of fields */ | |
62 | }; | |
63 | ||
64 | struct lttng_perf_counter_field { | |
65 | struct perf_event_attr attr; | |
66 | struct cds_list_head thread_field_list; /* Per-field list of thread fields */ | |
67 | }; | |
68 | ||
69 | static pthread_key_t perf_counter_key; | |
70 | ||
71 | static | |
72 | size_t perf_counter_get_size(size_t offset) | |
73 | { | |
74 | size_t size = 0; | |
75 | ||
76 | size += lib_ring_buffer_align(offset, lttng_alignof(uint64_t)); | |
77 | size += sizeof(uint64_t); | |
78 | return size; | |
79 | } | |
80 | ||
81 | #if defined(__x86_64__) || defined(__i386__) | |
82 | ||
83 | static | |
84 | uint64_t rdpmc(unsigned int counter) | |
85 | { | |
86 | unsigned int low, high; | |
87 | ||
88 | asm volatile("rdpmc" : "=a" (low), "=d" (high) : "c" (counter)); | |
89 | ||
90 | return low | ((uint64_t) high) << 32; | |
91 | } | |
92 | ||
93 | #else /* defined(__x86_64__) || defined(__i386__) */ | |
94 | ||
95 | #error "Perf event counters are only supported on x86 so far." | |
96 | ||
97 | #endif /* #else defined(__x86_64__) || defined(__i386__) */ | |
98 | ||
99 | static | |
100 | uint64_t read_perf_counter(struct perf_event_mmap_page *pc) | |
101 | { | |
102 | uint32_t seq, idx; | |
103 | uint64_t count; | |
104 | ||
105 | if (caa_unlikely(!pc)) | |
106 | return 0; | |
107 | ||
108 | do { | |
109 | seq = CMM_LOAD_SHARED(pc->lock); | |
110 | cmm_barrier(); | |
111 | ||
112 | idx = pc->index; | |
e83cec0b MD |
113 | if (idx) { |
114 | int64_t pmcval; | |
115 | ||
116 | pmcval = rdpmc(idx - 1); | |
117 | /* Sign-extend the pmc register result. */ | |
118 | pmcval <<= 64 - pc->pmc_width; | |
119 | pmcval >>= 64 - pc->pmc_width; | |
120 | count = pc->offset + pmcval; | |
121 | } else { | |
d58d1454 | 122 | count = 0; |
e83cec0b | 123 | } |
d58d1454 MD |
124 | cmm_barrier(); |
125 | } while (CMM_LOAD_SHARED(pc->lock) != seq); | |
126 | ||
127 | return count; | |
128 | } | |
129 | ||
130 | static | |
131 | int sys_perf_event_open(struct perf_event_attr *attr, | |
132 | pid_t pid, int cpu, int group_fd, | |
133 | unsigned long flags) | |
134 | { | |
135 | return syscall(SYS_perf_event_open, attr, pid, cpu, | |
136 | group_fd, flags); | |
137 | } | |
138 | ||
139 | static | |
140 | struct perf_event_mmap_page *setup_perf(struct perf_event_attr *attr) | |
141 | { | |
142 | void *perf_addr; | |
6c2125af | 143 | int fd, ret; |
d58d1454 MD |
144 | |
145 | fd = sys_perf_event_open(attr, 0, -1, -1, 0); | |
146 | if (fd < 0) | |
147 | return NULL; | |
148 | ||
149 | perf_addr = mmap(NULL, sizeof(struct perf_event_mmap_page), | |
150 | PROT_READ, MAP_SHARED, fd, 0); | |
151 | if (perf_addr == MAP_FAILED) | |
152 | return NULL; | |
6c2125af MD |
153 | ret = close(fd); |
154 | if (ret) { | |
155 | perror("Error closing LTTng-UST perf memory mapping FD"); | |
156 | } | |
d58d1454 MD |
157 | return perf_addr; |
158 | } | |
159 | ||
160 | static | |
161 | void unmap_perf_page(struct perf_event_mmap_page *pc) | |
162 | { | |
163 | int ret; | |
164 | ||
165 | if (!pc) | |
166 | return; | |
167 | ret = munmap(pc, sizeof(struct perf_event_mmap_page)); | |
168 | if (ret < 0) { | |
169 | PERROR("Error in munmap"); | |
170 | abort(); | |
171 | } | |
172 | } | |
173 | ||
174 | static | |
175 | struct lttng_perf_counter_thread *alloc_perf_counter_thread(void) | |
176 | { | |
177 | struct lttng_perf_counter_thread *perf_thread; | |
178 | sigset_t newmask, oldmask; | |
179 | int ret; | |
180 | ||
181 | ret = sigfillset(&newmask); | |
182 | if (ret) | |
183 | abort(); | |
184 | ret = pthread_sigmask(SIG_BLOCK, &newmask, &oldmask); | |
185 | if (ret) | |
186 | abort(); | |
187 | /* Check again with signals disabled */ | |
188 | perf_thread = pthread_getspecific(perf_counter_key); | |
189 | if (perf_thread) | |
190 | goto skip; | |
191 | perf_thread = zmalloc(sizeof(*perf_thread)); | |
192 | if (!perf_thread) | |
193 | abort(); | |
194 | CDS_INIT_LIST_HEAD(&perf_thread->rcu_field_list); | |
195 | ret = pthread_setspecific(perf_counter_key, perf_thread); | |
196 | if (ret) | |
197 | abort(); | |
198 | skip: | |
199 | ret = pthread_sigmask(SIG_SETMASK, &oldmask, NULL); | |
200 | if (ret) | |
201 | abort(); | |
202 | return perf_thread; | |
203 | } | |
204 | ||
205 | static | |
206 | struct lttng_perf_counter_thread_field * | |
207 | add_thread_field(struct lttng_perf_counter_field *perf_field, | |
208 | struct lttng_perf_counter_thread *perf_thread) | |
209 | { | |
210 | struct lttng_perf_counter_thread_field *thread_field; | |
211 | sigset_t newmask, oldmask; | |
212 | int ret; | |
213 | ||
214 | ret = sigfillset(&newmask); | |
215 | if (ret) | |
216 | abort(); | |
217 | ret = pthread_sigmask(SIG_BLOCK, &newmask, &oldmask); | |
218 | if (ret) | |
219 | abort(); | |
220 | /* Check again with signals disabled */ | |
221 | cds_list_for_each_entry_rcu(thread_field, &perf_thread->rcu_field_list, | |
222 | rcu_field_node) { | |
223 | if (thread_field->field == perf_field) | |
224 | goto skip; | |
225 | } | |
226 | thread_field = zmalloc(sizeof(*thread_field)); | |
227 | if (!thread_field) | |
228 | abort(); | |
229 | thread_field->field = perf_field; | |
230 | thread_field->pc = setup_perf(&perf_field->attr); | |
231 | /* Note: thread_field->pc can be NULL if setup_perf() fails. */ | |
232 | ust_lock_nocheck(); | |
233 | cds_list_add_rcu(&thread_field->rcu_field_node, | |
234 | &perf_thread->rcu_field_list); | |
235 | cds_list_add(&thread_field->thread_field_node, | |
236 | &perf_field->thread_field_list); | |
237 | ust_unlock(); | |
238 | skip: | |
239 | ret = pthread_sigmask(SIG_SETMASK, &oldmask, NULL); | |
240 | if (ret) | |
241 | abort(); | |
242 | return thread_field; | |
243 | } | |
244 | ||
245 | static | |
246 | struct lttng_perf_counter_thread_field * | |
247 | get_thread_field(struct lttng_perf_counter_field *field) | |
248 | { | |
249 | struct lttng_perf_counter_thread *perf_thread; | |
250 | struct lttng_perf_counter_thread_field *thread_field; | |
251 | ||
252 | perf_thread = pthread_getspecific(perf_counter_key); | |
253 | if (!perf_thread) | |
254 | perf_thread = alloc_perf_counter_thread(); | |
255 | cds_list_for_each_entry_rcu(thread_field, &perf_thread->rcu_field_list, | |
256 | rcu_field_node) { | |
257 | if (thread_field->field == field) | |
258 | return thread_field; | |
259 | } | |
260 | /* perf_counter_thread_field not found, need to add one */ | |
261 | return add_thread_field(field, perf_thread); | |
262 | } | |
263 | ||
264 | static | |
265 | uint64_t wrapper_perf_counter_read(struct lttng_ctx_field *field) | |
266 | { | |
267 | struct lttng_perf_counter_field *perf_field; | |
268 | struct lttng_perf_counter_thread_field *perf_thread_field; | |
269 | ||
270 | perf_field = field->u.perf_counter; | |
271 | perf_thread_field = get_thread_field(perf_field); | |
272 | return read_perf_counter(perf_thread_field->pc); | |
273 | } | |
274 | ||
275 | static | |
276 | void perf_counter_record(struct lttng_ctx_field *field, | |
277 | struct lttng_ust_lib_ring_buffer_ctx *ctx, | |
278 | struct lttng_channel *chan) | |
279 | { | |
280 | uint64_t value; | |
281 | ||
282 | value = wrapper_perf_counter_read(field); | |
283 | lib_ring_buffer_align_ctx(ctx, lttng_alignof(value)); | |
284 | chan->ops->event_write(ctx, &value, sizeof(value)); | |
285 | } | |
286 | ||
287 | static | |
288 | void perf_counter_get_value(struct lttng_ctx_field *field, | |
289 | union lttng_ctx_value *value) | |
290 | { | |
291 | uint64_t v; | |
292 | ||
293 | v = wrapper_perf_counter_read(field); | |
294 | value->s64 = v; | |
295 | } | |
296 | ||
297 | /* Called with UST lock held */ | |
298 | static | |
299 | void lttng_destroy_perf_thread_field( | |
300 | struct lttng_perf_counter_thread_field *thread_field) | |
301 | { | |
302 | unmap_perf_page(thread_field->pc); | |
303 | cds_list_del_rcu(&thread_field->rcu_field_node); | |
304 | cds_list_del(&thread_field->thread_field_node); | |
305 | free(thread_field); | |
306 | } | |
307 | ||
308 | static | |
309 | void lttng_destroy_perf_thread_key(void *_key) | |
310 | { | |
311 | struct lttng_perf_counter_thread *perf_thread = _key; | |
312 | struct lttng_perf_counter_thread_field *pos, *p; | |
313 | ||
314 | ust_lock_nocheck(); | |
315 | cds_list_for_each_entry_safe(pos, p, &perf_thread->rcu_field_list, | |
316 | rcu_field_node) | |
317 | lttng_destroy_perf_thread_field(pos); | |
318 | ust_unlock(); | |
319 | free(perf_thread); | |
320 | } | |
321 | ||
322 | /* Called with UST lock held */ | |
323 | static | |
324 | void lttng_destroy_perf_counter_field(struct lttng_ctx_field *field) | |
325 | { | |
326 | struct lttng_perf_counter_field *perf_field; | |
327 | struct lttng_perf_counter_thread_field *pos, *p; | |
328 | ||
329 | free((char *) field->event_field.name); | |
330 | perf_field = field->u.perf_counter; | |
331 | /* | |
332 | * This put is performed when no threads can concurrently | |
333 | * perform a "get" concurrently, thanks to urcu-bp grace | |
334 | * period. | |
335 | */ | |
336 | cds_list_for_each_entry_safe(pos, p, &perf_field->thread_field_list, | |
337 | thread_field_node) | |
338 | lttng_destroy_perf_thread_field(pos); | |
339 | free(perf_field); | |
340 | } | |
341 | ||
342 | /* Called with UST lock held */ | |
343 | int lttng_add_perf_counter_to_ctx(uint32_t type, | |
344 | uint64_t config, | |
345 | const char *name, | |
346 | struct lttng_ctx **ctx) | |
347 | { | |
348 | struct lttng_ctx_field *field; | |
349 | struct lttng_perf_counter_field *perf_field; | |
350 | struct perf_event_mmap_page *tmp_pc; | |
351 | char *name_alloc; | |
352 | int ret; | |
353 | ||
354 | name_alloc = strdup(name); | |
355 | if (!name_alloc) { | |
356 | ret = -ENOMEM; | |
357 | goto name_alloc_error; | |
358 | } | |
359 | perf_field = zmalloc(sizeof(*perf_field)); | |
360 | if (!perf_field) { | |
361 | ret = -ENOMEM; | |
362 | goto perf_field_alloc_error; | |
363 | } | |
364 | field = lttng_append_context(ctx); | |
365 | if (!field) { | |
366 | ret = -ENOMEM; | |
367 | goto append_context_error; | |
368 | } | |
369 | if (lttng_find_context(*ctx, name_alloc)) { | |
370 | ret = -EEXIST; | |
371 | goto find_error; | |
372 | } | |
373 | ||
374 | field->destroy = lttng_destroy_perf_counter_field; | |
375 | ||
376 | field->event_field.name = name_alloc; | |
377 | field->event_field.type.atype = atype_integer; | |
378 | field->event_field.type.u.basic.integer.size = | |
379 | sizeof(uint64_t) * CHAR_BIT; | |
380 | field->event_field.type.u.basic.integer.alignment = | |
381 | lttng_alignof(uint64_t) * CHAR_BIT; | |
382 | field->event_field.type.u.basic.integer.signedness = | |
383 | lttng_is_signed_type(uint64_t); | |
384 | field->event_field.type.u.basic.integer.reverse_byte_order = 0; | |
385 | field->event_field.type.u.basic.integer.base = 10; | |
386 | field->event_field.type.u.basic.integer.encoding = lttng_encode_none; | |
387 | field->get_size = perf_counter_get_size; | |
388 | field->record = perf_counter_record; | |
389 | field->get_value = perf_counter_get_value; | |
390 | ||
391 | perf_field->attr.type = type; | |
392 | perf_field->attr.config = config; | |
393 | perf_field->attr.exclude_kernel = 1; | |
394 | CDS_INIT_LIST_HEAD(&perf_field->thread_field_list); | |
395 | field->u.perf_counter = perf_field; | |
396 | ||
397 | /* Ensure that this perf counter can be used in this process. */ | |
398 | tmp_pc = setup_perf(&perf_field->attr); | |
399 | if (!tmp_pc) { | |
400 | ret = -ENODEV; | |
401 | goto setup_error; | |
402 | } | |
403 | unmap_perf_page(tmp_pc); | |
404 | ||
405 | /* | |
406 | * Contexts can only be added before tracing is started, so we | |
407 | * don't have to synchronize against concurrent threads using | |
408 | * the field here. | |
409 | */ | |
410 | ||
b2cc986a | 411 | lttng_context_update(*ctx); |
d58d1454 MD |
412 | return 0; |
413 | ||
414 | setup_error: | |
415 | find_error: | |
416 | lttng_remove_context_field(ctx, field); | |
417 | append_context_error: | |
418 | free(perf_field); | |
419 | perf_field_alloc_error: | |
420 | free(name_alloc); | |
421 | name_alloc_error: | |
422 | return ret; | |
423 | } | |
424 | ||
425 | int lttng_perf_counter_init(void) | |
426 | { | |
427 | int ret; | |
428 | ||
429 | ret = pthread_key_create(&perf_counter_key, | |
430 | lttng_destroy_perf_thread_key); | |
431 | if (ret) | |
432 | ret = -ret; | |
433 | return ret; | |
434 | } | |
435 | ||
436 | void lttng_perf_counter_exit(void) | |
437 | { | |
438 | int ret; | |
439 | ||
440 | ret = pthread_key_delete(perf_counter_key); | |
441 | if (ret) { | |
442 | errno = ret; | |
443 | PERROR("Error in pthread_key_delete"); | |
444 | } | |
445 | } |