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 "session.h"
   9 #include "thread.h"
  10 #include "thread-stack.h"
  11 #include "util.h"
  12 #include "debug.h"
  13 #include "namespaces.h"
  14 #include "comm.h"
  15 #include "unwind.h"
  16
  17 #include <api/fs/fs.h>
  18
  19 int thread__init_map_groups(struct thread *thread, struct machine *machine)
  20 {
  21         pid_t pid = thread->pid_;
  22
  23         if (pid == thread->tid || pid == -1) {
  24                 thread->mg = map_groups__new(machine);
  25         } else {
  26                 struct thread *leader = __machine__findnew_thread(machine, pid, pid);
  27                 if (leader) {
  28                         thread->mg = map_groups__get(leader->mg);
  29                         thread__put(leader);
  30                 }
  31         }
  32
  33         return thread->mg ? 0 : -1;
  34 }
  35
  36 struct thread *thread__new(pid_t pid, pid_t tid)
  37 {
  38         char *comm_str;
  39         struct comm *comm;
  40         struct thread *thread = zalloc(sizeof(*thread));
  41
  42         if (thread != NULL) {
  43                 thread->pid_ = pid;
  44                 thread->tid = tid;
  45                 thread->ppid = -1;
  46                 thread->cpu = -1;
  47                 INIT_LIST_HEAD(&thread->namespaces_list);
  48                 INIT_LIST_HEAD(&thread->comm_list);
  49                 init_rwsem(&thread->namespaces_lock);
  50                 init_rwsem(&thread->comm_lock);
  51
  52                 comm_str = malloc(32);
  53                 if (!comm_str)
  54                         goto err_thread;
  55
  56                 snprintf(comm_str, 32, ":%d", tid);
  57                 comm = comm__new(comm_str, 0, false);
  58                 free(comm_str);
  59                 if (!comm)
  60                         goto err_thread;
  61
  62                 list_add(&comm->list, &thread->comm_list);
  63                 refcount_set(&thread->refcnt, 1);
  64                 RB_CLEAR_NODE(&thread->rb_node);
  65                 /* Thread holds first ref to nsdata. */
  66                 thread->nsinfo = nsinfo__new(pid);
  67         }
  68
  69         return thread;
  70
  71 err_thread:
  72         free(thread);
  73         return NULL;
  74 }
  75
  76 void thread__delete(struct thread *thread)
  77 {
  78         struct namespaces *namespaces, *tmp_namespaces;
  79         struct comm *comm, *tmp_comm;
  80
  81         BUG_ON(!RB_EMPTY_NODE(&thread->rb_node));
  82
  83         thread_stack__free(thread);
  84
  85         if (thread->mg) {
  86                 map_groups__put(thread->mg);
  87                 thread->mg = NULL;
  88         }
  89         down_write(&thread->namespaces_lock);
  90         list_for_each_entry_safe(namespaces, tmp_namespaces,
  91                                  &thread->namespaces_list, list) {
  92                 list_del(&namespaces->list);
  93                 namespaces__free(namespaces);
  94         }
  95         up_write(&thread->namespaces_lock);
  96
  97         down_write(&thread->comm_lock);
  98         list_for_each_entry_safe(comm, tmp_comm, &thread->comm_list, list) {
  99                 list_del(&comm->list);
 100                 comm__free(comm);
 101         }
 102         up_write(&thread->comm_lock);
 103
 104         unwind__finish_access(thread);
 105         nsinfo__zput(thread->nsinfo);
 106
 107         exit_rwsem(&thread->namespaces_lock);
 108         exit_rwsem(&thread->comm_lock);
 109         free(thread);
 110 }
 111
 112 struct thread *thread__get(struct thread *thread)
 113 {
 114         if (thread)
 115                 refcount_inc(&thread->refcnt);
 116         return thread;
 117 }
 118
 119 void thread__put(struct thread *thread)
 120 {
 121         if (thread && refcount_dec_and_test(&thread->refcnt)) {
 122                 /*
 123                  * Remove it from the dead_threads list, as last reference
 124                  * is gone.
 125                  */
 126                 list_del_init(&thread->node);
 127                 thread__delete(thread);
 128         }
 129 }
 130
 131 static struct namespaces *__thread__namespaces(const struct thread *thread)
 132 {
 133         if (list_empty(&thread->namespaces_list))
 134                 return NULL;
 135
 136         return list_first_entry(&thread->namespaces_list, struct namespaces, list);
 137 }
 138
 139 struct namespaces *thread__namespaces(const struct thread *thread)
 140 {
 141         struct namespaces *ns;
 142
 143         down_read((struct rw_semaphore *)&thread->namespaces_lock);
 144         ns = __thread__namespaces(thread);
 145         up_read((struct rw_semaphore *)&thread->namespaces_lock);
 146
 147         return ns;
 148 }
 149
 150 static int __thread__set_namespaces(struct thread *thread, u64 timestamp,
 151                                     struct namespaces_event *event)
 152 {
 153         struct namespaces *new, *curr = __thread__namespaces(thread);
 154
 155         new = namespaces__new(event);
 156         if (!new)
 157                 return -ENOMEM;
 158
 159         list_add(&new->list, &thread->namespaces_list);
 160
 161         if (timestamp && curr) {
 162                 /*
 163                  * setns syscall must have changed few or all the namespaces
 164                  * of this thread. Update end time for the namespaces
 165                  * previously used.
 166                  */
 167                 curr = list_next_entry(new, list);
 168                 curr->end_time = timestamp;
 169         }
 170
 171         return 0;
 172 }
 173
 174 int thread__set_namespaces(struct thread *thread, u64 timestamp,
 175                            struct namespaces_event *event)
 176 {
 177         int ret;
 178
 179         down_write(&thread->namespaces_lock);
 180         ret = __thread__set_namespaces(thread, timestamp, event);
 181         up_write(&thread->namespaces_lock);
 182         return ret;
 183 }
 184
 185 struct comm *thread__comm(const struct thread *thread)
 186 {
 187         if (list_empty(&thread->comm_list))
 188                 return NULL;
 189
 190         return list_first_entry(&thread->comm_list, struct comm, list);
 191 }
 192
 193 struct comm *thread__exec_comm(const struct thread *thread)
 194 {
 195         struct comm *comm, *last = NULL, *second_last = NULL;
 196
 197         list_for_each_entry(comm, &thread->comm_list, list) {
 198                 if (comm->exec)
 199                         return comm;
 200                 second_last = last;
 201                 last = comm;
 202         }
 203
 204         /*
 205          * 'last' with no start time might be the parent's comm of a synthesized
 206          * thread (created by processing a synthesized fork event). For a main
 207          * thread, that is very probably wrong. Prefer a later comm to avoid
 208          * that case.
 209          */
 210         if (second_last && !last->start && thread->pid_ == thread->tid)
 211                 return second_last;
 212
 213         return last;
 214 }
 215
 216 static int ____thread__set_comm(struct thread *thread, const char *str,
 217                                 u64 timestamp, bool exec)
 218 {
 219         struct comm *new, *curr = thread__comm(thread);
 220
 221         /* Override the default :tid entry */
 222         if (!thread->comm_set) {
 223                 int err = comm__override(curr, str, timestamp, exec);
 224                 if (err)
 225                         return err;
 226         } else {
 227                 new = comm__new(str, timestamp, exec);
 228                 if (!new)
 229                         return -ENOMEM;
 230                 list_add(&new->list, &thread->comm_list);
 231
 232                 if (exec)
 233                         unwind__flush_access(thread);
 234         }
 235
 236         thread->comm_set = true;
 237
 238         return 0;
 239 }
 240
 241 int __thread__set_comm(struct thread *thread, const char *str, u64 timestamp,
 242                        bool exec)
 243 {
 244         int ret;
 245
 246         down_write(&thread->comm_lock);
 247         ret = ____thread__set_comm(thread, str, timestamp, exec);
 248         up_write(&thread->comm_lock);
 249         return ret;
 250 }
 251
 252 int thread__set_comm_from_proc(struct thread *thread)
 253 {
 254         char path[64];
 255         char *comm = NULL;
 256         size_t sz;
 257         int err = -1;
 258
 259         if (!(snprintf(path, sizeof(path), "%d/task/%d/comm",
 260                        thread->pid_, thread->tid) >= (int)sizeof(path)) &&
 261             procfs__read_str(path, &comm, &sz) == 0) {
 262                 comm[sz - 1] = '\0';
 263                 err = thread__set_comm(thread, comm, 0);
 264         }
 265
 266         return err;
 267 }
 268
 269 static const char *__thread__comm_str(const struct thread *thread)
 270 {
 271         const struct comm *comm = thread__comm(thread);
 272
 273         if (!comm)
 274                 return NULL;
 275
 276         return comm__str(comm);
 277 }
 278
 279 const char *thread__comm_str(const struct thread *thread)
 280 {
 281         const char *str;
 282
 283         down_read((struct rw_semaphore *)&thread->comm_lock);
 284         str = __thread__comm_str(thread);
 285         up_read((struct rw_semaphore *)&thread->comm_lock);
 286
 287         return str;
 288 }
 289
 290 /* CHECKME: it should probably better return the max comm len from its comm list */
 291 int thread__comm_len(struct thread *thread)
 292 {
 293         if (!thread->comm_len) {
 294                 const char *comm = thread__comm_str(thread);
 295                 if (!comm)
 296                         return 0;
 297                 thread->comm_len = strlen(comm);
 298         }
 299
 300         return thread->comm_len;
 301 }
 302
 303 size_t thread__fprintf(struct thread *thread, FILE *fp)
 304 {
 305         return fprintf(fp, "Thread %d %s\n", thread->tid, thread__comm_str(thread)) +
 306                map_groups__fprintf(thread->mg, fp);
 307 }
 308
 309 int thread__insert_map(struct thread *thread, struct map *map)
 310 {
 311         int ret;
 312
 313         ret = unwind__prepare_access(thread, map, NULL);
 314         if (ret)
 315                 return ret;
 316
 317         map_groups__fixup_overlappings(thread->mg, map, stderr);
 318         map_groups__insert(thread->mg, map);
 319
 320         return 0;
 321 }
 322
 323 static int __thread__prepare_access(struct thread *thread)
 324 {
 325         bool initialized = false;
 326         int err = 0;
 327         struct maps *maps = &thread->mg->maps;
 328         struct map *map;
 329
 330         down_read(&maps->lock);
 331
 332         for (map = maps__first(maps); map; map = map__next(map)) {
 333                 err = unwind__prepare_access(thread, map, &initialized);
 334                 if (err || initialized)
 335                         break;
 336         }
 337
 338         up_read(&maps->lock);
 339
 340         return err;
 341 }
 342
 343 static int thread__prepare_access(struct thread *thread)
 344 {
 345         int err = 0;
 346
 347         if (symbol_conf.use_callchain)
 348                 err = __thread__prepare_access(thread);
 349
 350         return err;
 351 }
 352
 353 static int thread__clone_map_groups(struct thread *thread,
 354                                     struct thread *parent)
 355 {
 356         /* This is new thread, we share map groups for process. */
 357         if (thread->pid_ == parent->pid_)
 358                 return thread__prepare_access(thread);
 359
 360         if (thread->mg == parent->mg) {
 361                 pr_debug("broken map groups on thread %d/%d parent %d/%d\n",
 362                          thread->pid_, thread->tid, parent->pid_, parent->tid);
 363                 return 0;
 364         }
 365
 366         /* But this one is new process, copy maps. */
 367         if (map_groups__clone(thread, parent->mg) < 0)
 368                 return -ENOMEM;
 369
 370         return 0;
 371 }
 372
 373 int thread__fork(struct thread *thread, struct thread *parent, u64 timestamp)
 374 {
 375         if (parent->comm_set) {
 376                 const char *comm = thread__comm_str(parent);
 377                 int err;
 378                 if (!comm)
 379                         return -ENOMEM;
 380                 err = thread__set_comm(thread, comm, timestamp);
 381                 if (err)
 382                         return err;
 383         }
 384
 385         thread->ppid = parent->tid;
 386         return thread__clone_map_groups(thread, parent);
 387 }
 388
 389 void thread__find_cpumode_addr_location(struct thread *thread, u64 addr,
 390                                         struct addr_location *al)
 391 {
 392         size_t i;
 393         const u8 cpumodes[] = {
 394                 PERF_RECORD_MISC_USER,
 395                 PERF_RECORD_MISC_KERNEL,
 396                 PERF_RECORD_MISC_GUEST_USER,
 397                 PERF_RECORD_MISC_GUEST_KERNEL
 398         };
 399
 400         for (i = 0; i < ARRAY_SIZE(cpumodes); i++) {
 401                 thread__find_symbol(thread, cpumodes[i], addr, al);
 402                 if (al->map)
 403                         break;
 404         }
 405 }
 406
 407 struct thread *thread__main_thread(struct machine *machine, struct thread *thread)
 408 {
 409         if (thread->pid_ == thread->tid)
 410                 return thread__get(thread);
 411
 412         if (thread->pid_ == -1)
 413                 return NULL;
 414
 415         return machine__find_thread(machine, thread->pid_, thread->pid_);
 416 }