kernel/tools/perf/util/thread-stack.c

   1 /*
   2  * thread-stack.c: Synthesize a thread's stack using call / return events
   3  * Copyright (c) 2014, Intel Corporation.
   4  *
   5  * This program is free software; you can redistribute it and/or modify it
   6  * under the terms and conditions of the GNU General Public License,
   7  * version 2, as published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  12  * more details.
  13  *
  14  */
  15
  16 #include <linux/rbtree.h>
  17 #include <linux/list.h>
  18 #include "thread.h"
  19 #include "event.h"
  20 #include "machine.h"
  21 #include "util.h"
  22 #include "debug.h"
  23 #include "symbol.h"
  24 #include "comm.h"
  25 #include "thread-stack.h"
  26
  27 #define CALL_PATH_BLOCK_SHIFT 8
  28 #define CALL_PATH_BLOCK_SIZE (1 << CALL_PATH_BLOCK_SHIFT)
  29 #define CALL_PATH_BLOCK_MASK (CALL_PATH_BLOCK_SIZE - 1)
  30
  31 struct call_path_block {
  32         struct call_path cp[CALL_PATH_BLOCK_SIZE];
  33         struct list_head node;
  34 };
  35
  36 /**
  37  * struct call_path_root - root of all call paths.
  38  * @call_path: root call path
  39  * @blocks: list of blocks to store call paths
  40  * @next: next free space
  41  * @sz: number of spaces
  42  */
  43 struct call_path_root {
  44         struct call_path call_path;
  45         struct list_head blocks;
  46         size_t next;
  47         size_t sz;
  48 };
  49
  50 /**
  51  * struct call_return_processor - provides a call-back to consume call-return
  52  *                                information.
  53  * @cpr: call path root
  54  * @process: call-back that accepts call/return information
  55  * @data: anonymous data for call-back
  56  */
  57 struct call_return_processor {
  58         struct call_path_root *cpr;
  59         int (*process)(struct call_return *cr, void *data);
  60         void *data;
  61 };
  62
  63 #define STACK_GROWTH 2048
  64
  65 /**
  66  * struct thread_stack_entry - thread stack entry.
  67  * @ret_addr: return address
  68  * @timestamp: timestamp (if known)
  69  * @ref: external reference (e.g. db_id of sample)
  70  * @branch_count: the branch count when the entry was created
  71  * @cp: call path
  72  * @no_call: a 'call' was not seen
  73  */
  74 struct thread_stack_entry {
  75         u64 ret_addr;
  76         u64 timestamp;
  77         u64 ref;
  78         u64 branch_count;
  79         struct call_path *cp;
  80         bool no_call;
  81 };
  82
  83 /**
  84  * struct thread_stack - thread stack constructed from 'call' and 'return'
  85  *                       branch samples.
  86  * @stack: array that holds the stack
  87  * @cnt: number of entries in the stack
  88  * @sz: current maximum stack size
  89  * @trace_nr: current trace number
  90  * @branch_count: running branch count
  91  * @kernel_start: kernel start address
  92  * @last_time: last timestamp
  93  * @crp: call/return processor
  94  * @comm: current comm
  95  */
  96 struct thread_stack {
  97         struct thread_stack_entry *stack;
  98         size_t cnt;
  99         size_t sz;
 100         u64 trace_nr;
 101         u64 branch_count;
 102         u64 kernel_start;
 103         u64 last_time;
 104         struct call_return_processor *crp;
 105         struct comm *comm;
 106 };
 107
 108 static int thread_stack__grow(struct thread_stack *ts)
 109 {
 110         struct thread_stack_entry *new_stack;
 111         size_t sz, new_sz;
 112
 113         new_sz = ts->sz + STACK_GROWTH;
 114         sz = new_sz * sizeof(struct thread_stack_entry);
 115
 116         new_stack = realloc(ts->stack, sz);
 117         if (!new_stack)
 118                 return -ENOMEM;
 119
 120         ts->stack = new_stack;
 121         ts->sz = new_sz;
 122
 123         return 0;
 124 }
 125
 126 static struct thread_stack *thread_stack__new(struct thread *thread,
 127                                               struct call_return_processor *crp)
 128 {
 129         struct thread_stack *ts;
 130
 131         ts = zalloc(sizeof(struct thread_stack));
 132         if (!ts)
 133                 return NULL;
 134
 135         if (thread_stack__grow(ts)) {
 136                 free(ts);
 137                 return NULL;
 138         }
 139
 140         if (thread->mg && thread->mg->machine)
 141                 ts->kernel_start = machine__kernel_start(thread->mg->machine);
 142         else
 143                 ts->kernel_start = 1ULL << 63;
 144         ts->crp = crp;
 145
 146         return ts;
 147 }
 148
 149 static int thread_stack__push(struct thread_stack *ts, u64 ret_addr)
 150 {
 151         int err = 0;
 152
 153         if (ts->cnt == ts->sz) {
 154                 err = thread_stack__grow(ts);
 155                 if (err) {
 156                         pr_warning("Out of memory: discarding thread stack\n");
 157                         ts->cnt = 0;
 158                 }
 159         }
 160
 161         ts->stack[ts->cnt++].ret_addr = ret_addr;
 162
 163         return err;
 164 }
 165
 166 static void thread_stack__pop(struct thread_stack *ts, u64 ret_addr)
 167 {
 168         size_t i;
 169
 170         /*
 171          * In some cases there may be functions which are not seen to return.
 172          * For example when setjmp / longjmp has been used.  Or the perf context
 173          * switch in the kernel which doesn't stop and start tracing in exactly
 174          * the same code path.  When that happens the return address will be
 175          * further down the stack.  If the return address is not found at all,
 176          * we assume the opposite (i.e. this is a return for a call that wasn't
 177          * seen for some reason) and leave the stack alone.
 178          */
 179         for (i = ts->cnt; i; ) {
 180                 if (ts->stack[--i].ret_addr == ret_addr) {
 181                         ts->cnt = i;
 182                         return;
 183                 }
 184         }
 185 }
 186
 187 static bool thread_stack__in_kernel(struct thread_stack *ts)
 188 {
 189         if (!ts->cnt)
 190                 return false;
 191
 192         return ts->stack[ts->cnt - 1].cp->in_kernel;
 193 }
 194
 195 static int thread_stack__call_return(struct thread *thread,
 196                                      struct thread_stack *ts, size_t idx,
 197                                      u64 timestamp, u64 ref, bool no_return)
 198 {
 199         struct call_return_processor *crp = ts->crp;
 200         struct thread_stack_entry *tse;
 201         struct call_return cr = {
 202                 .thread = thread,
 203                 .comm = ts->comm,
 204                 .db_id = 0,
 205         };
 206
 207         tse = &ts->stack[idx];
 208         cr.cp = tse->cp;
 209         cr.call_time = tse->timestamp;
 210         cr.return_time = timestamp;
 211         cr.branch_count = ts->branch_count - tse->branch_count;
 212         cr.call_ref = tse->ref;
 213         cr.return_ref = ref;
 214         if (tse->no_call)
 215                 cr.flags |= CALL_RETURN_NO_CALL;
 216         if (no_return)
 217                 cr.flags |= CALL_RETURN_NO_RETURN;
 218
 219         return crp->process(&cr, crp->data);
 220 }
 221
 222 static int thread_stack__flush(struct thread *thread, struct thread_stack *ts)
 223 {
 224         struct call_return_processor *crp = ts->crp;
 225         int err;
 226
 227         if (!crp) {
 228                 ts->cnt = 0;
 229                 return 0;
 230         }
 231
 232         while (ts->cnt) {
 233                 err = thread_stack__call_return(thread, ts, --ts->cnt,
 234                                                 ts->last_time, 0, true);
 235                 if (err) {
 236                         pr_err("Error flushing thread stack!\n");
 237                         ts->cnt = 0;
 238                         return err;
 239                 }
 240         }
 241
 242         return 0;
 243 }
 244
 245 int thread_stack__event(struct thread *thread, u32 flags, u64 from_ip,
 246                         u64 to_ip, u16 insn_len, u64 trace_nr)
 247 {
 248         if (!thread)
 249                 return -EINVAL;
 250
 251         if (!thread->ts) {
 252                 thread->ts = thread_stack__new(thread, NULL);
 253                 if (!thread->ts) {
 254                         pr_warning("Out of memory: no thread stack\n");
 255                         return -ENOMEM;
 256                 }
 257                 thread->ts->trace_nr = trace_nr;
 258         }
 259
 260         /*
 261          * When the trace is discontinuous, the trace_nr changes.  In that case
 262          * the stack might be completely invalid.  Better to report nothing than
 263          * to report something misleading, so flush the stack.
 264          */
 265         if (trace_nr != thread->ts->trace_nr) {
 266                 if (thread->ts->trace_nr)
 267                         thread_stack__flush(thread, thread->ts);
 268                 thread->ts->trace_nr = trace_nr;
 269         }
 270
 271         /* Stop here if thread_stack__process() is in use */
 272         if (thread->ts->crp)
 273                 return 0;
 274
 275         if (flags & PERF_IP_FLAG_CALL) {
 276                 u64 ret_addr;
 277
 278                 if (!to_ip)
 279                         return 0;
 280                 ret_addr = from_ip + insn_len;
 281                 if (ret_addr == to_ip)
 282                         return 0; /* Zero-length calls are excluded */
 283                 return thread_stack__push(thread->ts, ret_addr);
 284         } else if (flags & PERF_IP_FLAG_RETURN) {
 285                 if (!from_ip)
 286                         return 0;
 287                 thread_stack__pop(thread->ts, to_ip);
 288         }
 289
 290         return 0;
 291 }
 292
 293 void thread_stack__set_trace_nr(struct thread *thread, u64 trace_nr)
 294 {
 295         if (!thread || !thread->ts)
 296                 return;
 297
 298         if (trace_nr != thread->ts->trace_nr) {
 299                 if (thread->ts->trace_nr)
 300                         thread_stack__flush(thread, thread->ts);
 301                 thread->ts->trace_nr = trace_nr;
 302         }
 303 }
 304
 305 void thread_stack__free(struct thread *thread)
 306 {
 307         if (thread->ts) {
 308                 thread_stack__flush(thread, thread->ts);
 309                 zfree(&thread->ts->stack);
 310                 zfree(&thread->ts);
 311         }
 312 }
 313
 314 void thread_stack__sample(struct thread *thread, struct ip_callchain *chain,
 315                           size_t sz, u64 ip)
 316 {
 317         size_t i;
 318
 319         if (!thread || !thread->ts)
 320                 chain->nr = 1;
 321         else
 322                 chain->nr = min(sz, thread->ts->cnt + 1);
 323
 324         chain->ips[0] = ip;
 325
 326         for (i = 1; i < chain->nr; i++)
 327                 chain->ips[i] = thread->ts->stack[thread->ts->cnt - i].ret_addr;
 328 }
 329
 330 static void call_path__init(struct call_path *cp, struct call_path *parent,
 331                             struct symbol *sym, u64 ip, bool in_kernel)
 332 {
 333         cp->parent = parent;
 334         cp->sym = sym;
 335         cp->ip = sym ? 0 : ip;
 336         cp->db_id = 0;
 337         cp->in_kernel = in_kernel;
 338         RB_CLEAR_NODE(&cp->rb_node);
 339         cp->children = RB_ROOT;
 340 }
 341
 342 static struct call_path_root *call_path_root__new(void)
 343 {
 344         struct call_path_root *cpr;
 345
 346         cpr = zalloc(sizeof(struct call_path_root));
 347         if (!cpr)
 348                 return NULL;
 349         call_path__init(&cpr->call_path, NULL, NULL, 0, false);
 350         INIT_LIST_HEAD(&cpr->blocks);
 351         return cpr;
 352 }
 353
 354 static void call_path_root__free(struct call_path_root *cpr)
 355 {
 356         struct call_path_block *pos, *n;
 357
 358         list_for_each_entry_safe(pos, n, &cpr->blocks, node) {
 359                 list_del(&pos->node);
 360                 free(pos);
 361         }
 362         free(cpr);
 363 }
 364
 365 static struct call_path *call_path__new(struct call_path_root *cpr,
 366                                         struct call_path *parent,
 367                                         struct symbol *sym, u64 ip,
 368                                         bool in_kernel)
 369 {
 370         struct call_path_block *cpb;
 371         struct call_path *cp;
 372         size_t n;
 373
 374         if (cpr->next < cpr->sz) {
 375                 cpb = list_last_entry(&cpr->blocks, struct call_path_block,
 376                                       node);
 377         } else {
 378                 cpb = zalloc(sizeof(struct call_path_block));
 379                 if (!cpb)
 380                         return NULL;
 381                 list_add_tail(&cpb->node, &cpr->blocks);
 382                 cpr->sz += CALL_PATH_BLOCK_SIZE;
 383         }
 384
 385         n = cpr->next++ & CALL_PATH_BLOCK_MASK;
 386         cp = &cpb->cp[n];
 387
 388         call_path__init(cp, parent, sym, ip, in_kernel);
 389
 390         return cp;
 391 }
 392
 393 static struct call_path *call_path__findnew(struct call_path_root *cpr,
 394                                             struct call_path *parent,
 395                                             struct symbol *sym, u64 ip, u64 ks)
 396 {
 397         struct rb_node **p;
 398         struct rb_node *node_parent = NULL;
 399         struct call_path *cp;
 400         bool in_kernel = ip >= ks;
 401
 402         if (sym)
 403                 ip = 0;
 404
 405         if (!parent)
 406                 return call_path__new(cpr, parent, sym, ip, in_kernel);
 407
 408         p = &parent->children.rb_node;
 409         while (*p != NULL) {
 410                 node_parent = *p;
 411                 cp = rb_entry(node_parent, struct call_path, rb_node);
 412
 413                 if (cp->sym == sym && cp->ip == ip)
 414                         return cp;
 415
 416                 if (sym < cp->sym || (sym == cp->sym && ip < cp->ip))
 417                         p = &(*p)->rb_left;
 418                 else
 419                         p = &(*p)->rb_right;
 420         }
 421
 422         cp = call_path__new(cpr, parent, sym, ip, in_kernel);
 423         if (!cp)
 424                 return NULL;
 425
 426         rb_link_node(&cp->rb_node, node_parent, p);
 427         rb_insert_color(&cp->rb_node, &parent->children);
 428
 429         return cp;
 430 }
 431
 432 struct call_return_processor *
 433 call_return_processor__new(int (*process)(struct call_return *cr, void *data),
 434                            void *data)
 435 {
 436         struct call_return_processor *crp;
 437
 438         crp = zalloc(sizeof(struct call_return_processor));
 439         if (!crp)
 440                 return NULL;
 441         crp->cpr = call_path_root__new();
 442         if (!crp->cpr)
 443                 goto out_free;
 444         crp->process = process;
 445         crp->data = data;
 446         return crp;
 447
 448 out_free:
 449         free(crp);
 450         return NULL;
 451 }
 452
 453 void call_return_processor__free(struct call_return_processor *crp)
 454 {
 455         if (crp) {
 456                 call_path_root__free(crp->cpr);
 457                 free(crp);
 458         }
 459 }
 460
 461 static int thread_stack__push_cp(struct thread_stack *ts, u64 ret_addr,
 462                                  u64 timestamp, u64 ref, struct call_path *cp,
 463                                  bool no_call)
 464 {
 465         struct thread_stack_entry *tse;
 466         int err;
 467
 468         if (ts->cnt == ts->sz) {
 469                 err = thread_stack__grow(ts);
 470                 if (err)
 471                         return err;
 472         }
 473
 474         tse = &ts->stack[ts->cnt++];
 475         tse->ret_addr = ret_addr;
 476         tse->timestamp = timestamp;
 477         tse->ref = ref;
 478         tse->branch_count = ts->branch_count;
 479         tse->cp = cp;
 480         tse->no_call = no_call;
 481
 482         return 0;
 483 }
 484
 485 static int thread_stack__pop_cp(struct thread *thread, struct thread_stack *ts,
 486                                 u64 ret_addr, u64 timestamp, u64 ref,
 487                                 struct symbol *sym)
 488 {
 489         int err;
 490
 491         if (!ts->cnt)
 492                 return 1;
 493
 494         if (ts->cnt == 1) {
 495                 struct thread_stack_entry *tse = &ts->stack[0];
 496
 497                 if (tse->cp->sym == sym)
 498                         return thread_stack__call_return(thread, ts, --ts->cnt,
 499                                                          timestamp, ref, false);
 500         }
 501
 502         if (ts->stack[ts->cnt - 1].ret_addr == ret_addr) {
 503                 return thread_stack__call_return(thread, ts, --ts->cnt,
 504                                                  timestamp, ref, false);
 505         } else {
 506                 size_t i = ts->cnt - 1;
 507
 508                 while (i--) {
 509                         if (ts->stack[i].ret_addr != ret_addr)
 510                                 continue;
 511                         i += 1;
 512                         while (ts->cnt > i) {
 513                                 err = thread_stack__call_return(thread, ts,
 514                                                                 --ts->cnt,
 515                                                                 timestamp, ref,
 516                                                                 true);
 517                                 if (err)
 518                                         return err;
 519                         }
 520                         return thread_stack__call_return(thread, ts, --ts->cnt,
 521                                                          timestamp, ref, false);
 522                 }
 523         }
 524
 525         return 1;
 526 }
 527
 528 static int thread_stack__bottom(struct thread *thread, struct thread_stack *ts,
 529                                 struct perf_sample *sample,
 530                                 struct addr_location *from_al,
 531                                 struct addr_location *to_al, u64 ref)
 532 {
 533         struct call_path_root *cpr = ts->crp->cpr;
 534         struct call_path *cp;
 535         struct symbol *sym;
 536         u64 ip;
 537
 538         if (sample->ip) {
 539                 ip = sample->ip;
 540                 sym = from_al->sym;
 541         } else if (sample->addr) {
 542                 ip = sample->addr;
 543                 sym = to_al->sym;
 544         } else {
 545                 return 0;
 546         }
 547
 548         cp = call_path__findnew(cpr, &cpr->call_path, sym, ip,
 549                                 ts->kernel_start);
 550         if (!cp)
 551                 return -ENOMEM;
 552
 553         return thread_stack__push_cp(thread->ts, ip, sample->time, ref, cp,
 554                                      true);
 555 }
 556
 557 static int thread_stack__no_call_return(struct thread *thread,
 558                                         struct thread_stack *ts,
 559                                         struct perf_sample *sample,
 560                                         struct addr_location *from_al,
 561                                         struct addr_location *to_al, u64 ref)
 562 {
 563         struct call_path_root *cpr = ts->crp->cpr;
 564         struct call_path *cp, *parent;
 565         u64 ks = ts->kernel_start;
 566         int err;
 567
 568         if (sample->ip >= ks && sample->addr < ks) {
 569                 /* Return to userspace, so pop all kernel addresses */
 570                 while (thread_stack__in_kernel(ts)) {
 571                         err = thread_stack__call_return(thread, ts, --ts->cnt,
 572                                                         sample->time, ref,
 573                                                         true);
 574                         if (err)
 575                                 return err;
 576                 }
 577
 578                 /* If the stack is empty, push the userspace address */
 579                 if (!ts->cnt) {
 580                         cp = call_path__findnew(cpr, &cpr->call_path,
 581                                                 to_al->sym, sample->addr,
 582                                                 ts->kernel_start);
 583                         if (!cp)
 584                                 return -ENOMEM;
 585                         return thread_stack__push_cp(ts, 0, sample->time, ref,
 586                                                      cp, true);
 587                 }
 588         } else if (thread_stack__in_kernel(ts) && sample->ip < ks) {
 589                 /* Return to userspace, so pop all kernel addresses */
 590                 while (thread_stack__in_kernel(ts)) {
 591                         err = thread_stack__call_return(thread, ts, --ts->cnt,
 592                                                         sample->time, ref,
 593                                                         true);
 594                         if (err)
 595                                 return err;
 596                 }
 597         }
 598
 599         if (ts->cnt)
 600                 parent = ts->stack[ts->cnt - 1].cp;
 601         else
 602                 parent = &cpr->call_path;
 603
 604         /* This 'return' had no 'call', so push and pop top of stack */
 605         cp = call_path__findnew(cpr, parent, from_al->sym, sample->ip,
 606                                 ts->kernel_start);
 607         if (!cp)
 608                 return -ENOMEM;
 609
 610         err = thread_stack__push_cp(ts, sample->addr, sample->time, ref, cp,
 611                                     true);
 612         if (err)
 613                 return err;
 614
 615         return thread_stack__pop_cp(thread, ts, sample->addr, sample->time, ref,
 616                                     to_al->sym);
 617 }
 618
 619 static int thread_stack__trace_begin(struct thread *thread,
 620                                      struct thread_stack *ts, u64 timestamp,
 621                                      u64 ref)
 622 {
 623         struct thread_stack_entry *tse;
 624         int err;
 625
 626         if (!ts->cnt)
 627                 return 0;
 628
 629         /* Pop trace end */
 630         tse = &ts->stack[ts->cnt - 1];
 631         if (tse->cp->sym == NULL && tse->cp->ip == 0) {
 632                 err = thread_stack__call_return(thread, ts, --ts->cnt,
 633                                                 timestamp, ref, false);
 634                 if (err)
 635                         return err;
 636         }
 637
 638         return 0;
 639 }
 640
 641 static int thread_stack__trace_end(struct thread_stack *ts,
 642                                    struct perf_sample *sample, u64 ref)
 643 {
 644         struct call_path_root *cpr = ts->crp->cpr;
 645         struct call_path *cp;
 646         u64 ret_addr;
 647
 648         /* No point having 'trace end' on the bottom of the stack */
 649         if (!ts->cnt || (ts->cnt == 1 && ts->stack[0].ref == ref))
 650                 return 0;
 651
 652         cp = call_path__findnew(cpr, ts->stack[ts->cnt - 1].cp, NULL, 0,
 653                                 ts->kernel_start);
 654         if (!cp)
 655                 return -ENOMEM;
 656
 657         ret_addr = sample->ip + sample->insn_len;
 658
 659         return thread_stack__push_cp(ts, ret_addr, sample->time, ref, cp,
 660                                      false);
 661 }
 662
 663 int thread_stack__process(struct thread *thread, struct comm *comm,
 664                           struct perf_sample *sample,
 665                           struct addr_location *from_al,
 666                           struct addr_location *to_al, u64 ref,
 667                           struct call_return_processor *crp)
 668 {
 669         struct thread_stack *ts = thread->ts;
 670         int err = 0;
 671
 672         if (ts) {
 673                 if (!ts->crp) {
 674                         /* Supersede thread_stack__event() */
 675                         thread_stack__free(thread);
 676                         thread->ts = thread_stack__new(thread, crp);
 677                         if (!thread->ts)
 678                                 return -ENOMEM;
 679                         ts = thread->ts;
 680                         ts->comm = comm;
 681                 }
 682         } else {
 683                 thread->ts = thread_stack__new(thread, crp);
 684                 if (!thread->ts)
 685                         return -ENOMEM;
 686                 ts = thread->ts;
 687                 ts->comm = comm;
 688         }
 689
 690         /* Flush stack on exec */
 691         if (ts->comm != comm && thread->pid_ == thread->tid) {
 692                 err = thread_stack__flush(thread, ts);
 693                 if (err)
 694                         return err;
 695                 ts->comm = comm;
 696         }
 697
 698         /* If the stack is empty, put the current symbol on the stack */
 699         if (!ts->cnt) {
 700                 err = thread_stack__bottom(thread, ts, sample, from_al, to_al,
 701                                            ref);
 702                 if (err)
 703                         return err;
 704         }
 705
 706         ts->branch_count += 1;
 707         ts->last_time = sample->time;
 708
 709         if (sample->flags & PERF_IP_FLAG_CALL) {
 710                 struct call_path_root *cpr = ts->crp->cpr;
 711                 struct call_path *cp;
 712                 u64 ret_addr;
 713
 714                 if (!sample->ip || !sample->addr)
 715                         return 0;
 716
 717                 ret_addr = sample->ip + sample->insn_len;
 718                 if (ret_addr == sample->addr)
 719                         return 0; /* Zero-length calls are excluded */
 720
 721                 cp = call_path__findnew(cpr, ts->stack[ts->cnt - 1].cp,
 722                                         to_al->sym, sample->addr,
 723                                         ts->kernel_start);
 724                 if (!cp)
 725                         return -ENOMEM;
 726                 err = thread_stack__push_cp(ts, ret_addr, sample->time, ref,
 727                                             cp, false);
 728         } else if (sample->flags & PERF_IP_FLAG_RETURN) {
 729                 if (!sample->ip || !sample->addr)
 730                         return 0;
 731
 732                 err = thread_stack__pop_cp(thread, ts, sample->addr,
 733                                            sample->time, ref, from_al->sym);
 734                 if (err) {
 735                         if (err < 0)
 736                                 return err;
 737                         err = thread_stack__no_call_return(thread, ts, sample,
 738                                                            from_al, to_al, ref);
 739                 }
 740         } else if (sample->flags & PERF_IP_FLAG_TRACE_BEGIN) {
 741                 err = thread_stack__trace_begin(thread, ts, sample->time, ref);
 742         } else if (sample->flags & PERF_IP_FLAG_TRACE_END) {
 743                 err = thread_stack__trace_end(ts, sample, ref);
 744         }
 745
 746         return err;
 747 }