tools/perf/util/thread.c

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