root/tools/perf/util/thread.c

DEFINITIONS

1. thread__init_map_groups
2. thread__new
3. thread__delete
4. thread__get
5. thread__put
6. __thread__namespaces
7. thread__namespaces
8. __thread__set_namespaces
9. thread__set_namespaces
10. thread__comm
11. thread__exec_comm
12. ____thread__set_comm
13. __thread__set_comm
14. thread__set_comm_from_proc
15. __thread__comm_str
16. thread__comm_str
17. thread__comm_len
18. thread__fprintf
19. thread__insert_map
20. __thread__prepare_access
21. thread__prepare_access
22. thread__clone_map_groups
23. thread__fork
24. thread__find_cpumode_addr_location
25. thread__main_thread
26. thread__memcpy

   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_map_groups(struct thread *thread, struct machine *machine)
  23 {
  24         pid_t pid = thread->pid_;
  25 
  26         if (pid == thread->tid || pid == -1) {
  27                 thread->mg = map_groups__new(machine);
  28         } else {
  29                 struct thread *leader = __machine__findnew_thread(machine, pid, pid);
  30                 if (leader) {
  31                         thread->mg = map_groups__get(leader->mg);
  32                         thread__put(leader);
  33                 }
  34         }
  35 
  36         return thread->mg ? 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                 INIT_LIST_HEAD(&thread->namespaces_list);
  51                 INIT_LIST_HEAD(&thread->comm_list);
  52                 init_rwsem(&thread->namespaces_lock);
  53                 init_rwsem(&thread->comm_lock);
  54 
  55                 comm_str = malloc(32);
  56                 if (!comm_str)
  57                         goto err_thread;
  58 
  59                 snprintf(comm_str, 32, ":%d", tid);
  60                 comm = comm__new(comm_str, 0, false);
  61                 free(comm_str);
  62                 if (!comm)
  63                         goto err_thread;
  64 
  65                 list_add(&comm->list, &thread->comm_list);
  66                 refcount_set(&thread->refcnt, 1);
  67                 RB_CLEAR_NODE(&thread->rb_node);
  68                 /* Thread holds first ref to nsdata. */
  69                 thread->nsinfo = nsinfo__new(pid);
  70                 srccode_state_init(&thread->srccode_state);
  71         }
  72 
  73         return thread;
  74 
  75 err_thread:
  76         free(thread);
  77         return NULL;
  78 }
  79 
  80 void thread__delete(struct thread *thread)
  81 {
  82         struct namespaces *namespaces, *tmp_namespaces;
  83         struct comm *comm, *tmp_comm;
  84 
  85         BUG_ON(!RB_EMPTY_NODE(&thread->rb_node));
  86 
  87         thread_stack__free(thread);
  88 
  89         if (thread->mg) {
  90                 map_groups__put(thread->mg);
  91                 thread->mg = NULL;
  92         }
  93         down_write(&thread->namespaces_lock);
  94         list_for_each_entry_safe(namespaces, tmp_namespaces,
  95                                  &thread->namespaces_list, list) {
  96                 list_del_init(&namespaces->list);
  97                 namespaces__free(namespaces);
  98         }
  99         up_write(&thread->namespaces_lock);
 100 
 101         down_write(&thread->comm_lock);
 102         list_for_each_entry_safe(comm, tmp_comm, &thread->comm_list, list) {
 103                 list_del_init(&comm->list);
 104                 comm__free(comm);
 105         }
 106         up_write(&thread->comm_lock);
 107 
 108         nsinfo__zput(thread->nsinfo);
 109         srccode_state_free(&thread->srccode_state);
 110 
 111         exit_rwsem(&thread->namespaces_lock);
 112         exit_rwsem(&thread->comm_lock);
 113         free(thread);
 114 }
 115 
 116 struct thread *thread__get(struct thread *thread)
 117 {
 118         if (thread)
 119                 refcount_inc(&thread->refcnt);
 120         return thread;
 121 }
 122 
 123 void thread__put(struct thread *thread)
 124 {
 125         if (thread && refcount_dec_and_test(&thread->refcnt)) {
 126                 /*
 127                  * Remove it from the dead threads list, as last reference is
 128                  * gone, if it is in a dead threads list.
 129                  *
 130                  * We may not be there anymore if say, the machine where it was
 131                  * stored was already deleted, so we already removed it from
 132                  * the dead threads and some other piece of code still keeps a
 133                  * reference.
 134                  *
 135                  * This is what 'perf sched' does and finally drops it in
 136                  * perf_sched__lat(), where it calls perf_sched__read_events(),
 137                  * that processes the events by creating a session and deleting
 138                  * it, which ends up destroying the list heads for the dead
 139                  * threads, but before it does that it removes all threads from
 140                  * it using list_del_init().
 141                  *
 142                  * So we need to check here if it is in a dead threads list and
 143                  * if so, remove it before finally deleting the thread, to avoid
 144                  * an use after free situation.
 145                  */
 146                 if (!list_empty(&thread->node))
 147                         list_del_init(&thread->node);
 148                 thread__delete(thread);
 149         }
 150 }
 151 
 152 static struct namespaces *__thread__namespaces(const struct thread *thread)
 153 {
 154         if (list_empty(&thread->namespaces_list))
 155                 return NULL;
 156 
 157         return list_first_entry(&thread->namespaces_list, struct namespaces, list);
 158 }
 159 
 160 struct namespaces *thread__namespaces(struct thread *thread)
 161 {
 162         struct namespaces *ns;
 163 
 164         down_read(&thread->namespaces_lock);
 165         ns = __thread__namespaces(thread);
 166         up_read(&thread->namespaces_lock);
 167 
 168         return ns;
 169 }
 170 
 171 static int __thread__set_namespaces(struct thread *thread, u64 timestamp,
 172                                     struct perf_record_namespaces *event)
 173 {
 174         struct namespaces *new, *curr = __thread__namespaces(thread);
 175 
 176         new = namespaces__new(event);
 177         if (!new)
 178                 return -ENOMEM;
 179 
 180         list_add(&new->list, &thread->namespaces_list);
 181 
 182         if (timestamp && curr) {
 183                 /*
 184                  * setns syscall must have changed few or all the namespaces
 185                  * of this thread. Update end time for the namespaces
 186                  * previously used.
 187                  */
 188                 curr = list_next_entry(new, list);
 189                 curr->end_time = timestamp;
 190         }
 191 
 192         return 0;
 193 }
 194 
 195 int thread__set_namespaces(struct thread *thread, u64 timestamp,
 196                            struct perf_record_namespaces *event)
 197 {
 198         int ret;
 199 
 200         down_write(&thread->namespaces_lock);
 201         ret = __thread__set_namespaces(thread, timestamp, event);
 202         up_write(&thread->namespaces_lock);
 203         return ret;
 204 }
 205 
 206 struct comm *thread__comm(const struct thread *thread)
 207 {
 208         if (list_empty(&thread->comm_list))
 209                 return NULL;
 210 
 211         return list_first_entry(&thread->comm_list, struct comm, list);
 212 }
 213 
 214 struct comm *thread__exec_comm(const struct thread *thread)
 215 {
 216         struct comm *comm, *last = NULL, *second_last = NULL;
 217 
 218         list_for_each_entry(comm, &thread->comm_list, list) {
 219                 if (comm->exec)
 220                         return comm;
 221                 second_last = last;
 222                 last = comm;
 223         }
 224 
 225         /*
 226          * 'last' with no start time might be the parent's comm of a synthesized
 227          * thread (created by processing a synthesized fork event). For a main
 228          * thread, that is very probably wrong. Prefer a later comm to avoid
 229          * that case.
 230          */
 231         if (second_last && !last->start && thread->pid_ == thread->tid)
 232                 return second_last;
 233 
 234         return last;
 235 }
 236 
 237 static int ____thread__set_comm(struct thread *thread, const char *str,
 238                                 u64 timestamp, bool exec)
 239 {
 240         struct comm *new, *curr = thread__comm(thread);
 241 
 242         /* Override the default :tid entry */
 243         if (!thread->comm_set) {
 244                 int err = comm__override(curr, str, timestamp, exec);
 245                 if (err)
 246                         return err;
 247         } else {
 248                 new = comm__new(str, timestamp, exec);
 249                 if (!new)
 250                         return -ENOMEM;
 251                 list_add(&new->list, &thread->comm_list);
 252 
 253                 if (exec)
 254                         unwind__flush_access(thread->mg);
 255         }
 256 
 257         thread->comm_set = true;
 258 
 259         return 0;
 260 }
 261 
 262 int __thread__set_comm(struct thread *thread, const char *str, u64 timestamp,
 263                        bool exec)
 264 {
 265         int ret;
 266 
 267         down_write(&thread->comm_lock);
 268         ret = ____thread__set_comm(thread, str, timestamp, exec);
 269         up_write(&thread->comm_lock);
 270         return ret;
 271 }
 272 
 273 int thread__set_comm_from_proc(struct thread *thread)
 274 {
 275         char path[64];
 276         char *comm = NULL;
 277         size_t sz;
 278         int err = -1;
 279 
 280         if (!(snprintf(path, sizeof(path), "%d/task/%d/comm",
 281                        thread->pid_, thread->tid) >= (int)sizeof(path)) &&
 282             procfs__read_str(path, &comm, &sz) == 0) {
 283                 comm[sz - 1] = '\0';
 284                 err = thread__set_comm(thread, comm, 0);
 285         }
 286 
 287         return err;
 288 }
 289 
 290 static const char *__thread__comm_str(const struct thread *thread)
 291 {
 292         const struct comm *comm = thread__comm(thread);
 293 
 294         if (!comm)
 295                 return NULL;
 296 
 297         return comm__str(comm);
 298 }
 299 
 300 const char *thread__comm_str(struct thread *thread)
 301 {
 302         const char *str;
 303 
 304         down_read(&thread->comm_lock);
 305         str = __thread__comm_str(thread);
 306         up_read(&thread->comm_lock);
 307 
 308         return str;
 309 }
 310 
 311 /* CHECKME: it should probably better return the max comm len from its comm list */
 312 int thread__comm_len(struct thread *thread)
 313 {
 314         if (!thread->comm_len) {
 315                 const char *comm = thread__comm_str(thread);
 316                 if (!comm)
 317                         return 0;
 318                 thread->comm_len = strlen(comm);
 319         }
 320 
 321         return thread->comm_len;
 322 }
 323 
 324 size_t thread__fprintf(struct thread *thread, FILE *fp)
 325 {
 326         return fprintf(fp, "Thread %d %s\n", thread->tid, thread__comm_str(thread)) +
 327                map_groups__fprintf(thread->mg, fp);
 328 }
 329 
 330 int thread__insert_map(struct thread *thread, struct map *map)
 331 {
 332         int ret;
 333 
 334         ret = unwind__prepare_access(thread->mg, map, NULL);
 335         if (ret)
 336                 return ret;
 337 
 338         map_groups__fixup_overlappings(thread->mg, map, stderr);
 339         map_groups__insert(thread->mg, map);
 340 
 341         return 0;
 342 }
 343 
 344 static int __thread__prepare_access(struct thread *thread)
 345 {
 346         bool initialized = false;
 347         int err = 0;
 348         struct maps *maps = &thread->mg->maps;
 349         struct map *map;
 350 
 351         down_read(&maps->lock);
 352 
 353         for (map = maps__first(maps); map; map = map__next(map)) {
 354                 err = unwind__prepare_access(thread->mg, map, &initialized);
 355                 if (err || initialized)
 356                         break;
 357         }
 358 
 359         up_read(&maps->lock);
 360 
 361         return err;
 362 }
 363 
 364 static int thread__prepare_access(struct thread *thread)
 365 {
 366         int err = 0;
 367 
 368         if (dwarf_callchain_users)
 369                 err = __thread__prepare_access(thread);
 370 
 371         return err;
 372 }
 373 
 374 static int thread__clone_map_groups(struct thread *thread,
 375                                     struct thread *parent,
 376                                     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->mg == parent->mg) {
 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 ? map_groups__clone(thread, parent->mg) : 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_map_groups(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 }