tools/perf/util/thread.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include "../perf.h"
   3 #include <errno.h>
   4 #include <stdlib.h>
   5 #include <stdio.h>
   6 #include <string.h>
   7 #include <linux/kernel.h>
   8 #include <linux/zalloc.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         unwind__finish_access(thread);
 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         free(thread);
 115 }
 116
 117 struct thread *thread__get(struct thread *thread)
 118 {
 119         if (thread)
 120                 refcount_inc(&thread->refcnt);
 121         return thread;
 122 }
 123
 124 void thread__put(struct thread *thread)
 125 {
 126         if (thread && refcount_dec_and_test(&thread->refcnt)) {
 127                 /*
 128                  * Remove it from the dead threads list, as last reference is
 129                  * gone, if it is in a dead threads list.
 130                  *
 131                  * We may not be there anymore if say, the machine where it was
 132                  * stored was already deleted, so we already removed it from
 133                  * the dead threads and some other piece of code still keeps a
 134                  * reference.
 135                  *
 136                  * This is what 'perf sched' does and finally drops it in
 137                  * perf_sched__lat(), where it calls perf_sched__read_events(),
 138                  * that processes the events by creating a session and deleting
 139                  * it, which ends up destroying the list heads for the dead
 140                  * threads, but before it does that it removes all threads from
 141                  * it using list_del_init().
 142                  *
 143                  * So we need to check here if it is in a dead threads list and
 144                  * if so, remove it before finally deleting the thread, to avoid
 145                  * an use after free situation.
 146                  */
 147                 if (!list_empty(&thread->node))
 148                         list_del_init(&thread->node);
 149                 thread__delete(thread);
 150         }
 151 }
 152
 153 static struct namespaces *__thread__namespaces(const struct thread *thread)
 154 {
 155         if (list_empty(&thread->namespaces_list))
 156                 return NULL;
 157
 158         return list_first_entry(&thread->namespaces_list, struct namespaces, list);
 159 }
 160
 161 struct namespaces *thread__namespaces(struct thread *thread)
 162 {
 163         struct namespaces *ns;
 164
 165         down_read(&thread->namespaces_lock);
 166         ns = __thread__namespaces(thread);
 167         up_read(&thread->namespaces_lock);
 168
 169         return ns;
 170 }
 171
 172 static int __thread__set_namespaces(struct thread *thread, u64 timestamp,
 173                                     struct namespaces_event *event)
 174 {
 175         struct namespaces *new, *curr = __thread__namespaces(thread);
 176
 177         new = namespaces__new(event);
 178         if (!new)
 179                 return -ENOMEM;
 180
 181         list_add(&new->list, &thread->namespaces_list);
 182
 183         if (timestamp && curr) {
 184                 /*
 185                  * setns syscall must have changed few or all the namespaces
 186                  * of this thread. Update end time for the namespaces
 187                  * previously used.
 188                  */
 189                 curr = list_next_entry(new, list);
 190                 curr->end_time = timestamp;
 191         }
 192
 193         return 0;
 194 }
 195
 196 int thread__set_namespaces(struct thread *thread, u64 timestamp,
 197                            struct namespaces_event *event)
 198 {
 199         int ret;
 200
 201         down_write(&thread->namespaces_lock);
 202         ret = __thread__set_namespaces(thread, timestamp, event);
 203         up_write(&thread->namespaces_lock);
 204         return ret;
 205 }
 206
 207 struct comm *thread__comm(const struct thread *thread)
 208 {
 209         if (list_empty(&thread->comm_list))
 210                 return NULL;
 211
 212         return list_first_entry(&thread->comm_list, struct comm, list);
 213 }
 214
 215 struct comm *thread__exec_comm(const struct thread *thread)
 216 {
 217         struct comm *comm, *last = NULL, *second_last = NULL;
 218
 219         list_for_each_entry(comm, &thread->comm_list, list) {
 220                 if (comm->exec)
 221                         return comm;
 222                 second_last = last;
 223                 last = comm;
 224         }
 225
 226         /*
 227          * 'last' with no start time might be the parent's comm of a synthesized
 228          * thread (created by processing a synthesized fork event). For a main
 229          * thread, that is very probably wrong. Prefer a later comm to avoid
 230          * that case.
 231          */
 232         if (second_last && !last->start && thread->pid_ == thread->tid)
 233                 return second_last;
 234
 235         return last;
 236 }
 237
 238 static int ____thread__set_comm(struct thread *thread, const char *str,
 239                                 u64 timestamp, bool exec)
 240 {
 241         struct comm *new, *curr = thread__comm(thread);
 242
 243         /* Override the default :tid entry */
 244         if (!thread->comm_set) {
 245                 int err = comm__override(curr, str, timestamp, exec);
 246                 if (err)
 247                         return err;
 248         } else {
 249                 new = comm__new(str, timestamp, exec);
 250                 if (!new)
 251                         return -ENOMEM;
 252                 list_add(&new->list, &thread->comm_list);
 253
 254                 if (exec)
 255                         unwind__flush_access(thread);
 256         }
 257
 258         thread->comm_set = true;
 259
 260         return 0;
 261 }
 262
 263 int __thread__set_comm(struct thread *thread, const char *str, u64 timestamp,
 264                        bool exec)
 265 {
 266         int ret;
 267
 268         down_write(&thread->comm_lock);
 269         ret = ____thread__set_comm(thread, str, timestamp, exec);
 270         up_write(&thread->comm_lock);
 271         return ret;
 272 }
 273
 274 int thread__set_comm_from_proc(struct thread *thread)
 275 {
 276         char path[64];
 277         char *comm = NULL;
 278         size_t sz;
 279         int err = -1;
 280
 281         if (!(snprintf(path, sizeof(path), "%d/task/%d/comm",
 282                        thread->pid_, thread->tid) >= (int)sizeof(path)) &&
 283             procfs__read_str(path, &comm, &sz) == 0) {
 284                 comm[sz - 1] = '\0';
 285                 err = thread__set_comm(thread, comm, 0);
 286         }
 287
 288         return err;
 289 }
 290
 291 static const char *__thread__comm_str(const struct thread *thread)
 292 {
 293         const struct comm *comm = thread__comm(thread);
 294
 295         if (!comm)
 296                 return NULL;
 297
 298         return comm__str(comm);
 299 }
 300
 301 const char *thread__comm_str(struct thread *thread)
 302 {
 303         const char *str;
 304
 305         down_read(&thread->comm_lock);
 306         str = __thread__comm_str(thread);
 307         up_read(&thread->comm_lock);
 308
 309         return str;
 310 }
 311
 312 /* CHECKME: it should probably better return the max comm len from its comm list */
 313 int thread__comm_len(struct thread *thread)
 314 {
 315         if (!thread->comm_len) {
 316                 const char *comm = thread__comm_str(thread);
 317                 if (!comm)
 318                         return 0;
 319                 thread->comm_len = strlen(comm);
 320         }
 321
 322         return thread->comm_len;
 323 }
 324
 325 size_t thread__fprintf(struct thread *thread, FILE *fp)
 326 {
 327         return fprintf(fp, "Thread %d %s\n", thread->tid, thread__comm_str(thread)) +
 328                map_groups__fprintf(thread->mg, fp);
 329 }
 330
 331 int thread__insert_map(struct thread *thread, struct map *map)
 332 {
 333         int ret;
 334
 335         ret = unwind__prepare_access(thread, map, NULL);
 336         if (ret)
 337                 return ret;
 338
 339         map_groups__fixup_overlappings(thread->mg, map, stderr);
 340         map_groups__insert(thread->mg, map);
 341
 342         return 0;
 343 }
 344
 345 static int __thread__prepare_access(struct thread *thread)
 346 {
 347         bool initialized = false;
 348         int err = 0;
 349         struct maps *maps = &thread->mg->maps;
 350         struct map *map;
 351
 352         down_read(&maps->lock);
 353
 354         for (map = maps__first(maps); map; map = map__next(map)) {
 355                 err = unwind__prepare_access(thread, map, &initialized);
 356                 if (err || initialized)
 357                         break;
 358         }
 359
 360         up_read(&maps->lock);
 361
 362         return err;
 363 }
 364
 365 static int thread__prepare_access(struct thread *thread)
 366 {
 367         int err = 0;
 368
 369         if (dwarf_callchain_users)
 370                 err = __thread__prepare_access(thread);
 371
 372         return err;
 373 }
 374
 375 static int thread__clone_map_groups(struct thread *thread,
 376                                     struct thread *parent,
 377                                     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->mg == parent->mg) {
 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 ? map_groups__clone(thread, parent->mg) : 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_map_groups(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 }