thread.c

  1// SPDX-License-Identifier: GPL-2.0
  2#include <elf.h>
  3#include <errno.h>
  4#include <fcntl.h>
  5#include <stdlib.h>
  6#include <stdio.h>
  7#include <string.h>
  8#include <linux/kernel.h>
  9#include <linux/zalloc.h>
 10#include "dso.h"
 11#include "session.h"
 12#include "thread.h"
 13#include "thread-stack.h"
 14#include "debug.h"
 15#include "namespaces.h"
 16#include "comm.h"
 17#include "map.h"
 18#include "symbol.h"
 19#include "unwind.h"
 20#include "callchain.h"
 21#include "dwarf-regs.h"
 22
 23#include <api/fs/fs.h>
 24
 25int thread__init_maps(struct thread *thread, struct machine *machine)
 26{
 27	pid_t pid = thread__pid(thread);
 28
 29	if (pid == thread__tid(thread) || pid == -1) {
 30		thread__set_maps(thread, maps__new(machine));
 31	} else {
 32		struct thread *leader = machine__findnew_thread(machine, pid, pid);
 33
 34		if (leader) {
 35			thread__set_maps(thread, maps__get(thread__maps(leader)));
 36			thread__put(leader);
 37		}
 38	}
 39
 40	return thread__maps(thread) ? 0 : -1;
 41}
 42
 43struct thread *thread__new(pid_t pid, pid_t tid)
 44	NO_THREAD_SAFETY_ANALYSIS /* Allocation/creation is inherently single threaded. */
 45{
 46	RC_STRUCT(thread) *_thread = zalloc(sizeof(*_thread));
 47	struct thread *thread;
 48
 49	if (ADD_RC_CHK(thread, _thread) != NULL) {
 50		struct comm *comm;
 51		char comm_str[32];
 52
 53		thread__set_pid(thread, pid);
 54		thread__set_tid(thread, tid);
 55		thread__set_ppid(thread, -1);
 56		thread__set_cpu(thread, -1);
 57		thread__set_guest_cpu(thread, -1);
 58		thread__set_e_machine(thread, EM_NONE);
 59		thread__set_lbr_stitch_enable(thread, false);
 60		INIT_LIST_HEAD(thread__namespaces_list(thread));
 61		INIT_LIST_HEAD(thread__comm_list(thread));
 62		init_rwsem(thread__namespaces_lock(thread));
 63		init_rwsem(thread__comm_lock(thread));
 64
 65		snprintf(comm_str, sizeof(comm_str), ":%d", tid);
 66		comm = comm__new(comm_str, 0, false);
 67		if (!comm)
 68			goto err_thread;
 69
 70		list_add(&comm->list, thread__comm_list(thread));
 71		refcount_set(thread__refcnt(thread), 1);
 72		/* Thread holds first ref to nsdata. */
 73		RC_CHK_ACCESS(thread)->nsinfo = nsinfo__new(pid);
 74		srccode_state_init(thread__srccode_state(thread));
 75	}
 76
 77	return thread;
 78
 79err_thread:
 80	thread__delete(thread);
 81	return NULL;
 82}
 83
 84static void (*thread__priv_destructor)(void *priv);
 85
 86void thread__set_priv_destructor(void (*destructor)(void *priv))
 87{
 88	assert(thread__priv_destructor == NULL);
 89
 90	thread__priv_destructor = destructor;
 91}
 92
 93void thread__delete(struct thread *thread)
 94{
 95	struct namespaces *namespaces, *tmp_namespaces;
 96	struct comm *comm, *tmp_comm;
 97
 98	thread_stack__free(thread);
 99
100	if (thread__maps(thread)) {
101		maps__put(thread__maps(thread));
102		thread__set_maps(thread, NULL);
103	}
104	down_write(thread__namespaces_lock(thread));
105	list_for_each_entry_safe(namespaces, tmp_namespaces,
106				 thread__namespaces_list(thread), list) {
107		list_del_init(&namespaces->list);
108		namespaces__free(namespaces);
109	}
110	up_write(thread__namespaces_lock(thread));
111
112	down_write(thread__comm_lock(thread));
113	list_for_each_entry_safe(comm, tmp_comm, thread__comm_list(thread), list) {
114		list_del_init(&comm->list);
115		comm__free(comm);
116	}
117	up_write(thread__comm_lock(thread));
118
119	nsinfo__zput(RC_CHK_ACCESS(thread)->nsinfo);
120	srccode_state_free(thread__srccode_state(thread));
121
122	exit_rwsem(thread__namespaces_lock(thread));
123	exit_rwsem(thread__comm_lock(thread));
124	thread__free_stitch_list(thread);
125
126	if (thread__priv_destructor)
127		thread__priv_destructor(thread__priv(thread));
128
129	RC_CHK_FREE(thread);
130}
131
132struct thread *thread__get(struct thread *thread)
133{
134	struct thread *result;
135
136	if (RC_CHK_GET(result, thread))
137		refcount_inc(thread__refcnt(thread));
138
139	return result;
140}
141
142void thread__put(struct thread *thread)
143{
144	if (thread && refcount_dec_and_test(thread__refcnt(thread)))
145		thread__delete(thread);
146	else
147		RC_CHK_PUT(thread);
148}
149
150static struct namespaces *__thread__namespaces(struct thread *thread)
151{
152	if (list_empty(thread__namespaces_list(thread)))
153		return NULL;
154
155	return list_first_entry(thread__namespaces_list(thread), struct namespaces, list);
156}
157
158struct namespaces *thread__namespaces(struct thread *thread)
159{
160	struct namespaces *ns;
161
162	down_read(thread__namespaces_lock(thread));
163	ns = __thread__namespaces(thread);
164	up_read(thread__namespaces_lock(thread));
165
166	return ns;
167}
168
169static int __thread__set_namespaces(struct thread *thread, u64 timestamp,
170				    struct perf_record_namespaces *event)
171{
172	struct namespaces *new, *curr = __thread__namespaces(thread);
173
174	new = namespaces__new(event);
175	if (!new)
176		return -ENOMEM;
177
178	list_add(&new->list, thread__namespaces_list(thread));
179
180	if (timestamp && curr) {
181		/*
182		 * setns syscall must have changed few or all the namespaces
183		 * of this thread. Update end time for the namespaces
184		 * previously used.
185		 */
186		curr = list_next_entry(new, list);
187		curr->end_time = timestamp;
188	}
189
190	return 0;
191}
192
193int thread__set_namespaces(struct thread *thread, u64 timestamp,
194			   struct perf_record_namespaces *event)
195{
196	int ret;
197
198	down_write(thread__namespaces_lock(thread));
199	ret = __thread__set_namespaces(thread, timestamp, event);
200	up_write(thread__namespaces_lock(thread));
201	return ret;
202}
203
204static struct comm *__thread__comm(struct thread *thread)
205	SHARED_LOCKS_REQUIRED(thread__comm_lock(thread))
206{
207	if (list_empty(thread__comm_list(thread)))
208		return NULL;
209
210	return list_first_entry(thread__comm_list(thread), struct comm, list);
211}
212
213struct comm *thread__comm(struct thread *thread)
214{
215	struct comm *res = NULL;
216
217	down_read(thread__comm_lock(thread));
218	res = __thread__comm(thread);
219	up_read(thread__comm_lock(thread));
220	return res;
221}
222
223struct comm *thread__exec_comm(struct thread *thread)
224{
225	struct comm *comm, *last = NULL, *second_last = NULL;
226
227	down_read(thread__comm_lock(thread));
228	list_for_each_entry(comm, thread__comm_list(thread), list) {
229		if (comm->exec) {
230			up_read(thread__comm_lock(thread));
231			return comm;
232		}
233		second_last = last;
234		last = comm;
235	}
236	up_read(thread__comm_lock(thread));
237
238	/*
239	 * 'last' with no start time might be the parent's comm of a synthesized
240	 * thread (created by processing a synthesized fork event). For a main
241	 * thread, that is very probably wrong. Prefer a later comm to avoid
242	 * that case.
243	 */
244	if (second_last && !last->start && thread__pid(thread) == thread__tid(thread))
245		return second_last;
246
247	return last;
248}
249
250static int ____thread__set_comm(struct thread *thread, const char *str,
251				u64 timestamp, bool exec)
252	EXCLUSIVE_LOCKS_REQUIRED(thread__comm_lock(thread))
253{
254	struct comm *new, *curr = __thread__comm(thread);
255
256	/* Override the default :tid entry */
257	if (!thread__comm_set(thread)) {
258		int err = comm__override(curr, str, timestamp, exec);
259		if (err)
260			return err;
261	} else {
262		new = comm__new(str, timestamp, exec);
263		if (!new)
264			return -ENOMEM;
265		list_add(&new->list, thread__comm_list(thread));
266
267		if (exec)
268			unwind__flush_access(thread__maps(thread));
269	}
270
271	thread__set_comm_set(thread, true);
272
273	return 0;
274}
275
276int __thread__set_comm(struct thread *thread, const char *str, u64 timestamp,
277		       bool exec)
278{
279	int ret;
280
281	down_write(thread__comm_lock(thread));
282	ret = ____thread__set_comm(thread, str, timestamp, exec);
283	up_write(thread__comm_lock(thread));
284	return ret;
285}
286
287int thread__set_comm_from_proc(struct thread *thread)
288{
289	char path[64];
290	char *comm = NULL;
291	size_t sz;
292	int err = -1;
293
294	if (!(snprintf(path, sizeof(path), "%d/task/%d/comm",
295		       thread__pid(thread), thread__tid(thread)) >= (int)sizeof(path)) &&
296	    procfs__read_str(path, &comm, &sz) == 0) {
297		comm[sz - 1] = '\0';
298		err = thread__set_comm(thread, comm, 0);
299	}
300
301	return err;
302}
303
304static const char *__thread__comm_str(struct thread *thread)
305	SHARED_LOCKS_REQUIRED(thread__comm_lock(thread))
306{
307	const struct comm *comm = __thread__comm(thread);
308
309	if (!comm)
310		return NULL;
311
312	return comm__str(comm);
313}
314
315const char *thread__comm_str(struct thread *thread)
316{
317	const char *str;
318
319	down_read(thread__comm_lock(thread));
320	str = __thread__comm_str(thread);
321	up_read(thread__comm_lock(thread));
322
323	return str;
324}
325
326static int __thread__comm_len(struct thread *thread, const char *comm)
327{
328	if (!comm)
329		return 0;
330	thread__set_comm_len(thread, strlen(comm));
331
332	return thread__var_comm_len(thread);
333}
334
335/* CHECKME: it should probably better return the max comm len from its comm list */
336int thread__comm_len(struct thread *thread)
337{
338	int comm_len = thread__var_comm_len(thread);
339
340	if (!comm_len) {
341		const char *comm;
342
343		down_read(thread__comm_lock(thread));
344		comm = __thread__comm_str(thread);
345		comm_len = __thread__comm_len(thread, comm);
346		up_read(thread__comm_lock(thread));
347	}
348
349	return comm_len;
350}
351
352size_t thread__fprintf(struct thread *thread, FILE *fp)
353{
354	return fprintf(fp, "Thread %d %s\n", thread__tid(thread), thread__comm_str(thread)) +
355	       maps__fprintf(thread__maps(thread), fp);
356}
357
358int thread__insert_map(struct thread *thread, struct map *map)
359{
360	int ret;
361
362	ret = unwind__prepare_access(thread__maps(thread), map, NULL);
363	if (ret)
364		return ret;
365
366	return maps__fixup_overlap_and_insert(thread__maps(thread), map);
367}
368
369struct thread__prepare_access_maps_cb_args {
370	int err;
371	struct maps *maps;
372};
373
374static int thread__prepare_access_maps_cb(struct map *map, void *data)
375{
376	bool initialized = false;
377	struct thread__prepare_access_maps_cb_args *args = data;
378
379	args->err = unwind__prepare_access(args->maps, map, &initialized);
380
381	return (args->err || initialized) ? 1 : 0;
382}
383
384static int thread__prepare_access(struct thread *thread)
385{
386	struct thread__prepare_access_maps_cb_args args = {
387		.err = 0,
388	};
389
390	if (dwarf_callchain_users) {
391		args.maps = thread__maps(thread);
392		maps__for_each_map(thread__maps(thread), thread__prepare_access_maps_cb, &args);
393	}
394
395	return args.err;
396}
397
398static int thread__clone_maps(struct thread *thread, struct thread *parent, bool do_maps_clone)
399{
400	/* This is new thread, we share map groups for process. */
401	if (thread__pid(thread) == thread__pid(parent))
402		return thread__prepare_access(thread);
403
404	if (maps__equal(thread__maps(thread), thread__maps(parent))) {
405		pr_debug("broken map groups on thread %d/%d parent %d/%d\n",
406			 thread__pid(thread), thread__tid(thread),
407			 thread__pid(parent), thread__tid(parent));
408		return 0;
409	}
410	/* But this one is new process, copy maps. */
411	return do_maps_clone ? maps__copy_from(thread__maps(thread), thread__maps(parent)) : 0;
412}
413
414int thread__fork(struct thread *thread, struct thread *parent, u64 timestamp, bool do_maps_clone)
415{
416	if (thread__comm_set(parent)) {
417		const char *comm = thread__comm_str(parent);
418		int err;
419		if (!comm)
420			return -ENOMEM;
421		err = thread__set_comm(thread, comm, timestamp);
422		if (err)
423			return err;
424	}
425
426	thread__set_ppid(thread, thread__tid(parent));
427	return thread__clone_maps(thread, parent, do_maps_clone);
428}
429
430void thread__find_cpumode_addr_location(struct thread *thread, u64 addr,
431					bool symbols, struct addr_location *al)
432{
433	size_t i;
434	const u8 cpumodes[] = {
435		PERF_RECORD_MISC_USER,
436		PERF_RECORD_MISC_KERNEL,
437		PERF_RECORD_MISC_GUEST_USER,
438		PERF_RECORD_MISC_GUEST_KERNEL
439	};
440
441	for (i = 0; i < ARRAY_SIZE(cpumodes); i++) {
442		if (symbols)
443			thread__find_symbol(thread, cpumodes[i], addr, al);
444		else
445			thread__find_map(thread, cpumodes[i], addr, al);
446
447		if (al->map)
448			break;
449	}
450}
451
452static uint16_t read_proc_e_machine_for_pid(pid_t pid)
453{
454	char path[6 /* "/proc/" */ + 11 /* max length of pid */ + 5 /* "/exe\0" */];
455	int fd;
456	uint16_t e_machine = EM_NONE;
457
458	snprintf(path, sizeof(path), "/proc/%d/exe", pid);
459	fd = open(path, O_RDONLY);
460	if (fd >= 0) {
461		_Static_assert(offsetof(Elf32_Ehdr, e_machine) == 18, "Unexpected offset");
462		_Static_assert(offsetof(Elf64_Ehdr, e_machine) == 18, "Unexpected offset");
463		if (pread(fd, &e_machine, sizeof(e_machine), 18) != sizeof(e_machine))
464			e_machine = EM_NONE;
465		close(fd);
466	}
467	return e_machine;
468}
469
470static int thread__e_machine_callback(struct map *map, void *machine)
471{
472	struct dso *dso = map__dso(map);
473
474	_Static_assert(0 == EM_NONE, "Unexpected EM_NONE");
475	if (!dso)
476		return EM_NONE;
477
478	return dso__e_machine(dso, machine);
479}
480
481uint16_t thread__e_machine(struct thread *thread, struct machine *machine)
482{
483	pid_t tid, pid;
484	uint16_t e_machine = RC_CHK_ACCESS(thread)->e_machine;
485
486	if (e_machine != EM_NONE)
487		return e_machine;
488
489	tid = thread__tid(thread);
490	pid = thread__pid(thread);
491	if (pid != tid) {
492		struct thread *parent = machine__findnew_thread(machine, pid, pid);
493
494		if (parent) {
495			e_machine = thread__e_machine(parent, machine);
496			thread__put(parent);
497			thread__set_e_machine(thread, e_machine);
498			return e_machine;
499		}
500		/* Something went wrong, fallback. */
501	}
502	/* Reading on the PID thread. First try to find from the maps. */
503	e_machine = maps__for_each_map(thread__maps(thread),
504				       thread__e_machine_callback,
505				       machine);
506	if (e_machine == EM_NONE) {
507		/* Maps failed, perhaps we're live with map events disabled. */
508		bool is_live = machine->machines == NULL;
509
510		if (!is_live) {
511			/* Check if the session has a data file. */
512			struct perf_session *session = container_of(machine->machines,
513								    struct perf_session,
514								    machines);
515
516			is_live = !!session->data;
517		}
518		/* Read from /proc/pid/exe if live. */
519		if (is_live)
520			e_machine = read_proc_e_machine_for_pid(pid);
521	}
522	if (e_machine != EM_NONE)
523		thread__set_e_machine(thread, e_machine);
524	else
525		e_machine = EM_HOST;
526	return e_machine;
527}
528
529struct thread *thread__main_thread(struct machine *machine, struct thread *thread)
530{
531	if (thread__pid(thread) == thread__tid(thread))
532		return thread__get(thread);
533
534	if (thread__pid(thread) == -1)
535		return NULL;
536
537	return machine__find_thread(machine, thread__pid(thread), thread__pid(thread));
538}
539
540int thread__memcpy(struct thread *thread, struct machine *machine,
541		   void *buf, u64 ip, int len, bool *is64bit)
542{
543	u8 cpumode = PERF_RECORD_MISC_USER;
544	struct addr_location al;
545	struct dso *dso;
546	long offset;
547
548	if (machine__kernel_ip(machine, ip))
549		cpumode = PERF_RECORD_MISC_KERNEL;
550
551	addr_location__init(&al);
552	if (!thread__find_map(thread, cpumode, ip, &al)) {
553		addr_location__exit(&al);
554		return -1;
555	}
556
557	dso = map__dso(al.map);
558
559	if (!dso || dso__data(dso)->status == DSO_DATA_STATUS_ERROR || map__load(al.map) < 0) {
560		addr_location__exit(&al);
561		return -1;
562	}
563
564	offset = map__map_ip(al.map, ip);
565	if (is64bit)
566		*is64bit = dso__is_64_bit(dso);
567
568	addr_location__exit(&al);
569
570	return dso__data_read_offset(dso, machine, offset, buf, len);
571}
572
573void thread__free_stitch_list(struct thread *thread)
574{
575	struct lbr_stitch *lbr_stitch = thread__lbr_stitch(thread);
576	struct stitch_list *pos, *tmp;
577
578	if (!lbr_stitch)
579		return;
580
581	list_for_each_entry_safe(pos, tmp, &lbr_stitch->lists, node) {
582		map_symbol__exit(&pos->cursor.ms);
583		list_del_init(&pos->node);
584		free(pos);
585	}
586
587	list_for_each_entry_safe(pos, tmp, &lbr_stitch->free_lists, node) {
588		list_del_init(&pos->node);
589		free(pos);
590	}
591
592	for (unsigned int i = 0 ; i < lbr_stitch->prev_lbr_cursor_size; i++)
593		map_symbol__exit(&lbr_stitch->prev_lbr_cursor[i].ms);
594
595	zfree(&lbr_stitch->prev_lbr_cursor);
596	free(thread__lbr_stitch(thread));
597	thread__set_lbr_stitch(thread, NULL);
598}