xref: /openbmc/linux/tools/perf/util/thread.c (revision e2d413f9)
1 // SPDX-License-Identifier: GPL-2.0
2 #include <errno.h>
3 #include <stdlib.h>
4 #include <stdio.h>
5 #include <string.h>
6 #include <linux/kernel.h>
7 #include <linux/zalloc.h>
8 #include "dso.h"
9 #include "session.h"
10 #include "thread.h"
11 #include "thread-stack.h"
12 #include "debug.h"
13 #include "namespaces.h"
14 #include "comm.h"
15 #include "map.h"
16 #include "symbol.h"
17 #include "unwind.h"
18 #include "callchain.h"
19 
20 #include <api/fs/fs.h>
21 
22 int thread__init_maps(struct thread *thread, struct machine *machine)
23 {
24 	pid_t pid = thread->pid_;
25 
26 	if (pid == thread->tid || pid == -1) {
27 		thread->maps = maps__new(machine);
28 	} else {
29 		struct thread *leader = __machine__findnew_thread(machine, pid, pid);
30 		if (leader) {
31 			thread->maps = maps__get(leader->maps);
32 			thread__put(leader);
33 		}
34 	}
35 
36 	return thread->maps ? 0 : -1;
37 }
38 
39 struct thread *thread__new(pid_t pid, pid_t tid)
40 {
41 	char *comm_str;
42 	struct comm *comm;
43 	struct thread *thread = zalloc(sizeof(*thread));
44 
45 	if (thread != NULL) {
46 		thread->pid_ = pid;
47 		thread->tid = tid;
48 		thread->ppid = -1;
49 		thread->cpu = -1;
50 		thread->lbr_stitch_enable = false;
51 		INIT_LIST_HEAD(&thread->namespaces_list);
52 		INIT_LIST_HEAD(&thread->comm_list);
53 		init_rwsem(&thread->namespaces_lock);
54 		init_rwsem(&thread->comm_lock);
55 
56 		comm_str = malloc(32);
57 		if (!comm_str)
58 			goto err_thread;
59 
60 		snprintf(comm_str, 32, ":%d", tid);
61 		comm = comm__new(comm_str, 0, false);
62 		free(comm_str);
63 		if (!comm)
64 			goto err_thread;
65 
66 		list_add(&comm->list, &thread->comm_list);
67 		refcount_set(&thread->refcnt, 1);
68 		RB_CLEAR_NODE(&thread->rb_node);
69 		/* Thread holds first ref to nsdata. */
70 		thread->nsinfo = nsinfo__new(pid);
71 		srccode_state_init(&thread->srccode_state);
72 	}
73 
74 	return thread;
75 
76 err_thread:
77 	free(thread);
78 	return NULL;
79 }
80 
81 void thread__delete(struct thread *thread)
82 {
83 	struct namespaces *namespaces, *tmp_namespaces;
84 	struct comm *comm, *tmp_comm;
85 
86 	BUG_ON(!RB_EMPTY_NODE(&thread->rb_node));
87 
88 	thread_stack__free(thread);
89 
90 	if (thread->maps) {
91 		maps__put(thread->maps);
92 		thread->maps = NULL;
93 	}
94 	down_write(&thread->namespaces_lock);
95 	list_for_each_entry_safe(namespaces, tmp_namespaces,
96 				 &thread->namespaces_list, list) {
97 		list_del_init(&namespaces->list);
98 		namespaces__free(namespaces);
99 	}
100 	up_write(&thread->namespaces_lock);
101 
102 	down_write(&thread->comm_lock);
103 	list_for_each_entry_safe(comm, tmp_comm, &thread->comm_list, list) {
104 		list_del_init(&comm->list);
105 		comm__free(comm);
106 	}
107 	up_write(&thread->comm_lock);
108 
109 	nsinfo__zput(thread->nsinfo);
110 	srccode_state_free(&thread->srccode_state);
111 
112 	exit_rwsem(&thread->namespaces_lock);
113 	exit_rwsem(&thread->comm_lock);
114 	thread__free_stitch_list(thread);
115 	free(thread);
116 }
117 
118 struct thread *thread__get(struct thread *thread)
119 {
120 	if (thread)
121 		refcount_inc(&thread->refcnt);
122 	return thread;
123 }
124 
125 void thread__put(struct thread *thread)
126 {
127 	if (thread && refcount_dec_and_test(&thread->refcnt)) {
128 		/*
129 		 * Remove it from the dead threads list, as last reference is
130 		 * gone, if it is in a dead threads list.
131 		 *
132 		 * We may not be there anymore if say, the machine where it was
133 		 * stored was already deleted, so we already removed it from
134 		 * the dead threads and some other piece of code still keeps a
135 		 * reference.
136 		 *
137 		 * This is what 'perf sched' does and finally drops it in
138 		 * perf_sched__lat(), where it calls perf_sched__read_events(),
139 		 * that processes the events by creating a session and deleting
140 		 * it, which ends up destroying the list heads for the dead
141 		 * threads, but before it does that it removes all threads from
142 		 * it using list_del_init().
143 		 *
144 		 * So we need to check here if it is in a dead threads list and
145 		 * if so, remove it before finally deleting the thread, to avoid
146 		 * an use after free situation.
147 		 */
148 		if (!list_empty(&thread->node))
149 			list_del_init(&thread->node);
150 		thread__delete(thread);
151 	}
152 }
153 
154 static struct namespaces *__thread__namespaces(const struct thread *thread)
155 {
156 	if (list_empty(&thread->namespaces_list))
157 		return NULL;
158 
159 	return list_first_entry(&thread->namespaces_list, struct namespaces, list);
160 }
161 
162 struct namespaces *thread__namespaces(struct thread *thread)
163 {
164 	struct namespaces *ns;
165 
166 	down_read(&thread->namespaces_lock);
167 	ns = __thread__namespaces(thread);
168 	up_read(&thread->namespaces_lock);
169 
170 	return ns;
171 }
172 
173 static int __thread__set_namespaces(struct thread *thread, u64 timestamp,
174 				    struct perf_record_namespaces *event)
175 {
176 	struct namespaces *new, *curr = __thread__namespaces(thread);
177 
178 	new = namespaces__new(event);
179 	if (!new)
180 		return -ENOMEM;
181 
182 	list_add(&new->list, &thread->namespaces_list);
183 
184 	if (timestamp && curr) {
185 		/*
186 		 * setns syscall must have changed few or all the namespaces
187 		 * of this thread. Update end time for the namespaces
188 		 * previously used.
189 		 */
190 		curr = list_next_entry(new, list);
191 		curr->end_time = timestamp;
192 	}
193 
194 	return 0;
195 }
196 
197 int thread__set_namespaces(struct thread *thread, u64 timestamp,
198 			   struct perf_record_namespaces *event)
199 {
200 	int ret;
201 
202 	down_write(&thread->namespaces_lock);
203 	ret = __thread__set_namespaces(thread, timestamp, event);
204 	up_write(&thread->namespaces_lock);
205 	return ret;
206 }
207 
208 struct comm *thread__comm(const struct thread *thread)
209 {
210 	if (list_empty(&thread->comm_list))
211 		return NULL;
212 
213 	return list_first_entry(&thread->comm_list, struct comm, list);
214 }
215 
216 struct comm *thread__exec_comm(const struct thread *thread)
217 {
218 	struct comm *comm, *last = NULL, *second_last = NULL;
219 
220 	list_for_each_entry(comm, &thread->comm_list, list) {
221 		if (comm->exec)
222 			return comm;
223 		second_last = last;
224 		last = comm;
225 	}
226 
227 	/*
228 	 * 'last' with no start time might be the parent's comm of a synthesized
229 	 * thread (created by processing a synthesized fork event). For a main
230 	 * thread, that is very probably wrong. Prefer a later comm to avoid
231 	 * that case.
232 	 */
233 	if (second_last && !last->start && thread->pid_ == thread->tid)
234 		return second_last;
235 
236 	return last;
237 }
238 
239 static int ____thread__set_comm(struct thread *thread, const char *str,
240 				u64 timestamp, bool exec)
241 {
242 	struct comm *new, *curr = thread__comm(thread);
243 
244 	/* Override the default :tid entry */
245 	if (!thread->comm_set) {
246 		int err = comm__override(curr, str, timestamp, exec);
247 		if (err)
248 			return err;
249 	} else {
250 		new = comm__new(str, timestamp, exec);
251 		if (!new)
252 			return -ENOMEM;
253 		list_add(&new->list, &thread->comm_list);
254 
255 		if (exec)
256 			unwind__flush_access(thread->maps);
257 	}
258 
259 	thread->comm_set = true;
260 
261 	return 0;
262 }
263 
264 int __thread__set_comm(struct thread *thread, const char *str, u64 timestamp,
265 		       bool exec)
266 {
267 	int ret;
268 
269 	down_write(&thread->comm_lock);
270 	ret = ____thread__set_comm(thread, str, timestamp, exec);
271 	up_write(&thread->comm_lock);
272 	return ret;
273 }
274 
275 int thread__set_comm_from_proc(struct thread *thread)
276 {
277 	char path[64];
278 	char *comm = NULL;
279 	size_t sz;
280 	int err = -1;
281 
282 	if (!(snprintf(path, sizeof(path), "%d/task/%d/comm",
283 		       thread->pid_, thread->tid) >= (int)sizeof(path)) &&
284 	    procfs__read_str(path, &comm, &sz) == 0) {
285 		comm[sz - 1] = '\0';
286 		err = thread__set_comm(thread, comm, 0);
287 	}
288 
289 	return err;
290 }
291 
292 static const char *__thread__comm_str(const struct thread *thread)
293 {
294 	const struct comm *comm = thread__comm(thread);
295 
296 	if (!comm)
297 		return NULL;
298 
299 	return comm__str(comm);
300 }
301 
302 const char *thread__comm_str(struct thread *thread)
303 {
304 	const char *str;
305 
306 	down_read(&thread->comm_lock);
307 	str = __thread__comm_str(thread);
308 	up_read(&thread->comm_lock);
309 
310 	return str;
311 }
312 
313 /* CHECKME: it should probably better return the max comm len from its comm list */
314 int thread__comm_len(struct thread *thread)
315 {
316 	if (!thread->comm_len) {
317 		const char *comm = thread__comm_str(thread);
318 		if (!comm)
319 			return 0;
320 		thread->comm_len = strlen(comm);
321 	}
322 
323 	return thread->comm_len;
324 }
325 
326 size_t thread__fprintf(struct thread *thread, FILE *fp)
327 {
328 	return fprintf(fp, "Thread %d %s\n", thread->tid, thread__comm_str(thread)) +
329 	       maps__fprintf(thread->maps, fp);
330 }
331 
332 int thread__insert_map(struct thread *thread, struct map *map)
333 {
334 	int ret;
335 
336 	ret = unwind__prepare_access(thread->maps, map, NULL);
337 	if (ret)
338 		return ret;
339 
340 	maps__fixup_overlappings(thread->maps, map, stderr);
341 	maps__insert(thread->maps, map);
342 
343 	return 0;
344 }
345 
346 static int __thread__prepare_access(struct thread *thread)
347 {
348 	bool initialized = false;
349 	int err = 0;
350 	struct maps *maps = thread->maps;
351 	struct map *map;
352 
353 	down_read(&maps->lock);
354 
355 	maps__for_each_entry(maps, map) {
356 		err = unwind__prepare_access(thread->maps, map, &initialized);
357 		if (err || initialized)
358 			break;
359 	}
360 
361 	up_read(&maps->lock);
362 
363 	return err;
364 }
365 
366 static int thread__prepare_access(struct thread *thread)
367 {
368 	int err = 0;
369 
370 	if (dwarf_callchain_users)
371 		err = __thread__prepare_access(thread);
372 
373 	return err;
374 }
375 
376 static int thread__clone_maps(struct thread *thread, struct thread *parent, bool do_maps_clone)
377 {
378 	/* This is new thread, we share map groups for process. */
379 	if (thread->pid_ == parent->pid_)
380 		return thread__prepare_access(thread);
381 
382 	if (thread->maps == parent->maps) {
383 		pr_debug("broken map groups on thread %d/%d parent %d/%d\n",
384 			 thread->pid_, thread->tid, parent->pid_, parent->tid);
385 		return 0;
386 	}
387 	/* But this one is new process, copy maps. */
388 	return do_maps_clone ? maps__clone(thread, parent->maps) : 0;
389 }
390 
391 int thread__fork(struct thread *thread, struct thread *parent, u64 timestamp, bool do_maps_clone)
392 {
393 	if (parent->comm_set) {
394 		const char *comm = thread__comm_str(parent);
395 		int err;
396 		if (!comm)
397 			return -ENOMEM;
398 		err = thread__set_comm(thread, comm, timestamp);
399 		if (err)
400 			return err;
401 	}
402 
403 	thread->ppid = parent->tid;
404 	return thread__clone_maps(thread, parent, do_maps_clone);
405 }
406 
407 void thread__find_cpumode_addr_location(struct thread *thread, u64 addr,
408 					struct addr_location *al)
409 {
410 	size_t i;
411 	const u8 cpumodes[] = {
412 		PERF_RECORD_MISC_USER,
413 		PERF_RECORD_MISC_KERNEL,
414 		PERF_RECORD_MISC_GUEST_USER,
415 		PERF_RECORD_MISC_GUEST_KERNEL
416 	};
417 
418 	for (i = 0; i < ARRAY_SIZE(cpumodes); i++) {
419 		thread__find_symbol(thread, cpumodes[i], addr, al);
420 		if (al->map)
421 			break;
422 	}
423 }
424 
425 struct thread *thread__main_thread(struct machine *machine, struct thread *thread)
426 {
427 	if (thread->pid_ == thread->tid)
428 		return thread__get(thread);
429 
430 	if (thread->pid_ == -1)
431 		return NULL;
432 
433 	return machine__find_thread(machine, thread->pid_, thread->pid_);
434 }
435 
436 int thread__memcpy(struct thread *thread, struct machine *machine,
437 		   void *buf, u64 ip, int len, bool *is64bit)
438 {
439        u8 cpumode = PERF_RECORD_MISC_USER;
440        struct addr_location al;
441        long offset;
442 
443        if (machine__kernel_ip(machine, ip))
444                cpumode = PERF_RECORD_MISC_KERNEL;
445 
446        if (!thread__find_map(thread, cpumode, ip, &al) || !al.map->dso ||
447 	   al.map->dso->data.status == DSO_DATA_STATUS_ERROR ||
448 	   map__load(al.map) < 0)
449                return -1;
450 
451        offset = al.map->map_ip(al.map, ip);
452        if (is64bit)
453                *is64bit = al.map->dso->is_64_bit;
454 
455        return dso__data_read_offset(al.map->dso, machine, offset, buf, len);
456 }
457 
458 void thread__free_stitch_list(struct thread *thread)
459 {
460 	struct lbr_stitch *lbr_stitch = thread->lbr_stitch;
461 	struct stitch_list *pos, *tmp;
462 
463 	if (!lbr_stitch)
464 		return;
465 
466 	list_for_each_entry_safe(pos, tmp, &lbr_stitch->lists, node) {
467 		list_del_init(&pos->node);
468 		free(pos);
469 	}
470 
471 	list_for_each_entry_safe(pos, tmp, &lbr_stitch->free_lists, node) {
472 		list_del_init(&pos->node);
473 		free(pos);
474 	}
475 
476 	zfree(&lbr_stitch->prev_lbr_cursor);
477 	zfree(&thread->lbr_stitch);
478 }
479