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