gdb/btrace.c

   1 /* Branch trace support for GDB, the GNU debugger.
   2
   3    Copyright (C) 2013-2015 Free Software Foundation, Inc.
   4
   5    Contributed by Intel Corp. <markus.t.metzger@intel.com>
   6
   7    This file is part of GDB.
   8
   9    This program is free software; you can redistribute it and/or modify
  10    it under the terms of the GNU General Public License as published by
  11    the Free Software Foundation; either version 3 of the License, or
  12    (at your option) any later version.
  13
  14    This program is distributed in the hope that it will be useful,
  15    but WITHOUT ANY WARRANTY; without even the implied warranty of
  16    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17    GNU General Public License for more details.
  18
  19    You should have received a copy of the GNU General Public License
  20    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  21
  22 #include "defs.h"
  23 #include "btrace.h"
  24 #include "gdbthread.h"
  25 #include "inferior.h"
  26 #include "target.h"
  27 #include "record.h"
  28 #include "symtab.h"
  29 #include "disasm.h"
  30 #include "source.h"
  31 #include "filenames.h"
  32 #include "xml-support.h"
  33 #include "regcache.h"
  34
  35 /* Print a record debug message.  Use do ... while (0) to avoid ambiguities
  36    when used in if statements.  */
  37
  38 #define DEBUG(msg, args...)                                             \
  39   do                                                                    \
  40     {                                                                   \
  41       if (record_debug != 0)                                            \
  42         fprintf_unfiltered (gdb_stdlog,                                 \
  43                             "[btrace] " msg "\n", ##args);              \
  44     }                                                                   \
  45   while (0)
  46
  47 #define DEBUG_FTRACE(msg, args...) DEBUG ("[ftrace] " msg, ##args)
  48
  49 /* Return the function name of a recorded function segment for printing.
  50    This function never returns NULL.  */
  51
  52 static const char *
  53 ftrace_print_function_name (const struct btrace_function *bfun)
  54 {
  55   struct minimal_symbol *msym;
  56   struct symbol *sym;
  57
  58   msym = bfun->msym;
  59   sym = bfun->sym;
  60
  61   if (sym != NULL)
  62     return SYMBOL_PRINT_NAME (sym);
  63
  64   if (msym != NULL)
  65     return MSYMBOL_PRINT_NAME (msym);
  66
  67   return "<unknown>";
  68 }
  69
  70 /* Return the file name of a recorded function segment for printing.
  71    This function never returns NULL.  */
  72
  73 static const char *
  74 ftrace_print_filename (const struct btrace_function *bfun)
  75 {
  76   struct symbol *sym;
  77   const char *filename;
  78
  79   sym = bfun->sym;
  80
  81   if (sym != NULL)
  82     filename = symtab_to_filename_for_display (symbol_symtab (sym));
  83   else
  84     filename = "<unknown>";
  85
  86   return filename;
  87 }
  88
  89 /* Return a string representation of the address of an instruction.
  90    This function never returns NULL.  */
  91
  92 static const char *
  93 ftrace_print_insn_addr (const struct btrace_insn *insn)
  94 {
  95   if (insn == NULL)
  96     return "<nil>";
  97
  98   return core_addr_to_string_nz (insn->pc);
  99 }
 100
 101 /* Print an ftrace debug status message.  */
 102
 103 static void
 104 ftrace_debug (const struct btrace_function *bfun, const char *prefix)
 105 {
 106   const char *fun, *file;
 107   unsigned int ibegin, iend;
 108   int level;
 109
 110   fun = ftrace_print_function_name (bfun);
 111   file = ftrace_print_filename (bfun);
 112   level = bfun->level;
 113
 114   ibegin = bfun->insn_offset;
 115   iend = ibegin + VEC_length (btrace_insn_s, bfun->insn);
 116
 117   DEBUG_FTRACE ("%s: fun = %s, file = %s, level = %d, insn = [%u; %u)",
 118                 prefix, fun, file, level, ibegin, iend);
 119 }
 120
 121 /* Return non-zero if BFUN does not match MFUN and FUN,
 122    return zero otherwise.  */
 123
 124 static int
 125 ftrace_function_switched (const struct btrace_function *bfun,
 126                           const struct minimal_symbol *mfun,
 127                           const struct symbol *fun)
 128 {
 129   struct minimal_symbol *msym;
 130   struct symbol *sym;
 131
 132   msym = bfun->msym;
 133   sym = bfun->sym;
 134
 135   /* If the minimal symbol changed, we certainly switched functions.  */
 136   if (mfun != NULL && msym != NULL
 137       && strcmp (MSYMBOL_LINKAGE_NAME (mfun), MSYMBOL_LINKAGE_NAME (msym)) != 0)
 138     return 1;
 139
 140   /* If the symbol changed, we certainly switched functions.  */
 141   if (fun != NULL && sym != NULL)
 142     {
 143       const char *bfname, *fname;
 144
 145       /* Check the function name.  */
 146       if (strcmp (SYMBOL_LINKAGE_NAME (fun), SYMBOL_LINKAGE_NAME (sym)) != 0)
 147         return 1;
 148
 149       /* Check the location of those functions, as well.  */
 150       bfname = symtab_to_fullname (symbol_symtab (sym));
 151       fname = symtab_to_fullname (symbol_symtab (fun));
 152       if (filename_cmp (fname, bfname) != 0)
 153         return 1;
 154     }
 155
 156   /* If we lost symbol information, we switched functions.  */
 157   if (!(msym == NULL && sym == NULL) && mfun == NULL && fun == NULL)
 158     return 1;
 159
 160   /* If we gained symbol information, we switched functions.  */
 161   if (msym == NULL && sym == NULL && !(mfun == NULL && fun == NULL))
 162     return 1;
 163
 164   return 0;
 165 }
 166
 167 /* Allocate and initialize a new branch trace function segment.
 168    PREV is the chronologically preceding function segment.
 169    MFUN and FUN are the symbol information we have for this function.  */
 170
 171 static struct btrace_function *
 172 ftrace_new_function (struct btrace_function *prev,
 173                      struct minimal_symbol *mfun,
 174                      struct symbol *fun)
 175 {
 176   struct btrace_function *bfun;
 177
 178   bfun = xzalloc (sizeof (*bfun));
 179
 180   bfun->msym = mfun;
 181   bfun->sym = fun;
 182   bfun->flow.prev = prev;
 183
 184   if (prev == NULL)
 185     {
 186       /* Start counting at one.  */
 187       bfun->number = 1;
 188       bfun->insn_offset = 1;
 189     }
 190   else
 191     {
 192       gdb_assert (prev->flow.next == NULL);
 193       prev->flow.next = bfun;
 194
 195       bfun->number = prev->number + 1;
 196       bfun->insn_offset = (prev->insn_offset
 197                            + VEC_length (btrace_insn_s, prev->insn));
 198       bfun->level = prev->level;
 199     }
 200
 201   return bfun;
 202 }
 203
 204 /* Update the UP field of a function segment.  */
 205
 206 static void
 207 ftrace_update_caller (struct btrace_function *bfun,
 208                       struct btrace_function *caller,
 209                       enum btrace_function_flag flags)
 210 {
 211   if (bfun->up != NULL)
 212     ftrace_debug (bfun, "updating caller");
 213
 214   bfun->up = caller;
 215   bfun->flags = flags;
 216
 217   ftrace_debug (bfun, "set caller");
 218 }
 219
 220 /* Fix up the caller for all segments of a function.  */
 221
 222 static void
 223 ftrace_fixup_caller (struct btrace_function *bfun,
 224                      struct btrace_function *caller,
 225                      enum btrace_function_flag flags)
 226 {
 227   struct btrace_function *prev, *next;
 228
 229   ftrace_update_caller (bfun, caller, flags);
 230
 231   /* Update all function segments belonging to the same function.  */
 232   for (prev = bfun->segment.prev; prev != NULL; prev = prev->segment.prev)
 233     ftrace_update_caller (prev, caller, flags);
 234
 235   for (next = bfun->segment.next; next != NULL; next = next->segment.next)
 236     ftrace_update_caller (next, caller, flags);
 237 }
 238
 239 /* Add a new function segment for a call.
 240    CALLER is the chronologically preceding function segment.
 241    MFUN and FUN are the symbol information we have for this function.  */
 242
 243 static struct btrace_function *
 244 ftrace_new_call (struct btrace_function *caller,
 245                  struct minimal_symbol *mfun,
 246                  struct symbol *fun)
 247 {
 248   struct btrace_function *bfun;
 249
 250   bfun = ftrace_new_function (caller, mfun, fun);
 251   bfun->up = caller;
 252   bfun->level += 1;
 253
 254   ftrace_debug (bfun, "new call");
 255
 256   return bfun;
 257 }
 258
 259 /* Add a new function segment for a tail call.
 260    CALLER is the chronologically preceding function segment.
 261    MFUN and FUN are the symbol information we have for this function.  */
 262
 263 static struct btrace_function *
 264 ftrace_new_tailcall (struct btrace_function *caller,
 265                      struct minimal_symbol *mfun,
 266                      struct symbol *fun)
 267 {
 268   struct btrace_function *bfun;
 269
 270   bfun = ftrace_new_function (caller, mfun, fun);
 271   bfun->up = caller;
 272   bfun->level += 1;
 273   bfun->flags |= BFUN_UP_LINKS_TO_TAILCALL;
 274
 275   ftrace_debug (bfun, "new tail call");
 276
 277   return bfun;
 278 }
 279
 280 /* Find the innermost caller in the back trace of BFUN with MFUN/FUN
 281    symbol information.  */
 282
 283 static struct btrace_function *
 284 ftrace_find_caller (struct btrace_function *bfun,
 285                     struct minimal_symbol *mfun,
 286                     struct symbol *fun)
 287 {
 288   for (; bfun != NULL; bfun = bfun->up)
 289     {
 290       /* Skip functions with incompatible symbol information.  */
 291       if (ftrace_function_switched (bfun, mfun, fun))
 292         continue;
 293
 294       /* This is the function segment we're looking for.  */
 295       break;
 296     }
 297
 298   return bfun;
 299 }
 300
 301 /* Find the innermost caller in the back trace of BFUN, skipping all
 302    function segments that do not end with a call instruction (e.g.
 303    tail calls ending with a jump).  */
 304
 305 static struct btrace_function *
 306 ftrace_find_call (struct btrace_function *bfun)
 307 {
 308   for (; bfun != NULL; bfun = bfun->up)
 309     {
 310       struct btrace_insn *last;
 311
 312       /* Skip gaps.  */
 313       if (bfun->errcode != 0)
 314         continue;
 315
 316       last = VEC_last (btrace_insn_s, bfun->insn);
 317
 318       if (last->iclass == BTRACE_INSN_CALL)
 319         break;
 320     }
 321
 322   return bfun;
 323 }
 324
 325 /* Add a continuation segment for a function into which we return.
 326    PREV is the chronologically preceding function segment.
 327    MFUN and FUN are the symbol information we have for this function.  */
 328
 329 static struct btrace_function *
 330 ftrace_new_return (struct btrace_function *prev,
 331                    struct minimal_symbol *mfun,
 332                    struct symbol *fun)
 333 {
 334   struct btrace_function *bfun, *caller;
 335
 336   bfun = ftrace_new_function (prev, mfun, fun);
 337
 338   /* It is important to start at PREV's caller.  Otherwise, we might find
 339      PREV itself, if PREV is a recursive function.  */
 340   caller = ftrace_find_caller (prev->up, mfun, fun);
 341   if (caller != NULL)
 342     {
 343       /* The caller of PREV is the preceding btrace function segment in this
 344          function instance.  */
 345       gdb_assert (caller->segment.next == NULL);
 346
 347       caller->segment.next = bfun;
 348       bfun->segment.prev = caller;
 349
 350       /* Maintain the function level.  */
 351       bfun->level = caller->level;
 352
 353       /* Maintain the call stack.  */
 354       bfun->up = caller->up;
 355       bfun->flags = caller->flags;
 356
 357       ftrace_debug (bfun, "new return");
 358     }
 359   else
 360     {
 361       /* We did not find a caller.  This could mean that something went
 362          wrong or that the call is simply not included in the trace.  */
 363
 364       /* Let's search for some actual call.  */
 365       caller = ftrace_find_call (prev->up);
 366       if (caller == NULL)
 367         {
 368           /* There is no call in PREV's back trace.  We assume that the
 369              branch trace did not include it.  */
 370
 371           /* Let's find the topmost call function - this skips tail calls.  */
 372           while (prev->up != NULL)
 373             prev = prev->up;
 374
 375           /* We maintain levels for a series of returns for which we have
 376              not seen the calls.
 377              We start at the preceding function's level in case this has
 378              already been a return for which we have not seen the call.
 379              We start at level 0 otherwise, to handle tail calls correctly.  */
 380           bfun->level = min (0, prev->level) - 1;
 381
 382           /* Fix up the call stack for PREV.  */
 383           ftrace_fixup_caller (prev, bfun, BFUN_UP_LINKS_TO_RET);
 384
 385           ftrace_debug (bfun, "new return - no caller");
 386         }
 387       else
 388         {
 389           /* There is a call in PREV's back trace to which we should have
 390              returned.  Let's remain at this level.  */
 391           bfun->level = prev->level;
 392
 393           ftrace_debug (bfun, "new return - unknown caller");
 394         }
 395     }
 396
 397   return bfun;
 398 }
 399
 400 /* Add a new function segment for a function switch.
 401    PREV is the chronologically preceding function segment.
 402    MFUN and FUN are the symbol information we have for this function.  */
 403
 404 static struct btrace_function *
 405 ftrace_new_switch (struct btrace_function *prev,
 406                    struct minimal_symbol *mfun,
 407                    struct symbol *fun)
 408 {
 409   struct btrace_function *bfun;
 410
 411   /* This is an unexplained function switch.  The call stack will likely
 412      be wrong at this point.  */
 413   bfun = ftrace_new_function (prev, mfun, fun);
 414
 415   ftrace_debug (bfun, "new switch");
 416
 417   return bfun;
 418 }
 419
 420 /* Add a new function segment for a gap in the trace due to a decode error.
 421    PREV is the chronologically preceding function segment.
 422    ERRCODE is the format-specific error code.  */
 423
 424 static struct btrace_function *
 425 ftrace_new_gap (struct btrace_function *prev, int errcode)
 426 {
 427   struct btrace_function *bfun;
 428
 429   /* We hijack prev if it was empty.  */
 430   if (prev != NULL && prev->errcode == 0
 431       && VEC_empty (btrace_insn_s, prev->insn))
 432     bfun = prev;
 433   else
 434     bfun = ftrace_new_function (prev, NULL, NULL);
 435
 436   bfun->errcode = errcode;
 437
 438   ftrace_debug (bfun, "new gap");
 439
 440   return bfun;
 441 }
 442
 443 /* Update BFUN with respect to the instruction at PC.  This may create new
 444    function segments.
 445    Return the chronologically latest function segment, never NULL.  */
 446
 447 static struct btrace_function *
 448 ftrace_update_function (struct btrace_function *bfun, CORE_ADDR pc)
 449 {
 450   struct bound_minimal_symbol bmfun;
 451   struct minimal_symbol *mfun;
 452   struct symbol *fun;
 453   struct btrace_insn *last;
 454
 455   /* Try to determine the function we're in.  We use both types of symbols
 456      to avoid surprises when we sometimes get a full symbol and sometimes
 457      only a minimal symbol.  */
 458   fun = find_pc_function (pc);
 459   bmfun = lookup_minimal_symbol_by_pc (pc);
 460   mfun = bmfun.minsym;
 461
 462   if (fun == NULL && mfun == NULL)
 463     DEBUG_FTRACE ("no symbol at %s", core_addr_to_string_nz (pc));
 464
 465   /* If we didn't have a function or if we had a gap before, we create one.  */
 466   if (bfun == NULL || bfun->errcode != 0)
 467     return ftrace_new_function (bfun, mfun, fun);
 468
 469   /* Check the last instruction, if we have one.
 470      We do this check first, since it allows us to fill in the call stack
 471      links in addition to the normal flow links.  */
 472   last = NULL;
 473   if (!VEC_empty (btrace_insn_s, bfun->insn))
 474     last = VEC_last (btrace_insn_s, bfun->insn);
 475
 476   if (last != NULL)
 477     {
 478       switch (last->iclass)
 479         {
 480         case BTRACE_INSN_RETURN:
 481           {
 482             const char *fname;
 483
 484             /* On some systems, _dl_runtime_resolve returns to the resolved
 485                function instead of jumping to it.  From our perspective,
 486                however, this is a tailcall.
 487                If we treated it as return, we wouldn't be able to find the
 488                resolved function in our stack back trace.  Hence, we would
 489                lose the current stack back trace and start anew with an empty
 490                back trace.  When the resolved function returns, we would then
 491                create a stack back trace with the same function names but
 492                different frame id's.  This will confuse stepping.  */
 493             fname = ftrace_print_function_name (bfun);
 494             if (strcmp (fname, "_dl_runtime_resolve") == 0)
 495               return ftrace_new_tailcall (bfun, mfun, fun);
 496
 497             return ftrace_new_return (bfun, mfun, fun);
 498           }
 499
 500         case BTRACE_INSN_CALL:
 501           /* Ignore calls to the next instruction.  They are used for PIC.  */
 502           if (last->pc + last->size == pc)
 503             break;
 504
 505           return ftrace_new_call (bfun, mfun, fun);
 506
 507         case BTRACE_INSN_JUMP:
 508           {
 509             CORE_ADDR start;
 510
 511             start = get_pc_function_start (pc);
 512
 513             /* If we can't determine the function for PC, we treat a jump at
 514                the end of the block as tail call.  */
 515             if (start == 0 || start == pc)
 516               return ftrace_new_tailcall (bfun, mfun, fun);
 517           }
 518         }
 519     }
 520
 521   /* Check if we're switching functions for some other reason.  */
 522   if (ftrace_function_switched (bfun, mfun, fun))
 523     {
 524       DEBUG_FTRACE ("switching from %s in %s at %s",
 525                     ftrace_print_insn_addr (last),
 526                     ftrace_print_function_name (bfun),
 527                     ftrace_print_filename (bfun));
 528
 529       return ftrace_new_switch (bfun, mfun, fun);
 530     }
 531
 532   return bfun;
 533 }
 534
 535 /* Add the instruction at PC to BFUN's instructions.  */
 536
 537 static void
 538 ftrace_update_insns (struct btrace_function *bfun,
 539                      const struct btrace_insn *insn)
 540 {
 541   VEC_safe_push (btrace_insn_s, bfun->insn, insn);
 542
 543   if (record_debug > 1)
 544     ftrace_debug (bfun, "update insn");
 545 }
 546
 547 /* Classify the instruction at PC.  */
 548
 549 static enum btrace_insn_class
 550 ftrace_classify_insn (struct gdbarch *gdbarch, CORE_ADDR pc)
 551 {
 552   enum btrace_insn_class iclass;
 553
 554   iclass = BTRACE_INSN_OTHER;
 555   TRY
 556     {
 557       if (gdbarch_insn_is_call (gdbarch, pc))
 558         iclass = BTRACE_INSN_CALL;
 559       else if (gdbarch_insn_is_ret (gdbarch, pc))
 560         iclass = BTRACE_INSN_RETURN;
 561       else if (gdbarch_insn_is_jump (gdbarch, pc))
 562         iclass = BTRACE_INSN_JUMP;
 563     }
 564   CATCH (error, RETURN_MASK_ERROR)
 565     {
 566     }
 567   END_CATCH
 568
 569   return iclass;
 570 }
 571
 572 /* Compute the function branch trace from BTS trace.  */
 573
 574 static void
 575 btrace_compute_ftrace_bts (struct thread_info *tp,
 576                            const struct btrace_data_bts *btrace)
 577 {
 578   struct btrace_thread_info *btinfo;
 579   struct btrace_function *begin, *end;
 580   struct gdbarch *gdbarch;
 581   unsigned int blk, ngaps;
 582   int level;
 583
 584   gdbarch = target_gdbarch ();
 585   btinfo = &tp->btrace;
 586   begin = btinfo->begin;
 587   end = btinfo->end;
 588   ngaps = btinfo->ngaps;
 589   level = begin != NULL ? -btinfo->level : INT_MAX;
 590   blk = VEC_length (btrace_block_s, btrace->blocks);
 591
 592   while (blk != 0)
 593     {
 594       btrace_block_s *block;
 595       CORE_ADDR pc;
 596
 597       blk -= 1;
 598
 599       block = VEC_index (btrace_block_s, btrace->blocks, blk);
 600       pc = block->begin;
 601
 602       for (;;)
 603         {
 604           struct btrace_insn insn;
 605           int size;
 606
 607           /* We should hit the end of the block.  Warn if we went too far.  */
 608           if (block->end < pc)
 609             {
 610               /* Indicate the gap in the trace - unless we're at the
 611                  beginning.  */
 612               if (begin != NULL)
 613                 {
 614                   warning (_("Recorded trace may be corrupted around %s."),
 615                            core_addr_to_string_nz (pc));
 616
 617                   end = ftrace_new_gap (end, BDE_BTS_OVERFLOW);
 618                   ngaps += 1;
 619                 }
 620               break;
 621             }
 622
 623           end = ftrace_update_function (end, pc);
 624           if (begin == NULL)
 625             begin = end;
 626
 627           /* Maintain the function level offset.
 628              For all but the last block, we do it here.  */
 629           if (blk != 0)
 630             level = min (level, end->level);
 631
 632           size = 0;
 633           TRY
 634             {
 635               size = gdb_insn_length (gdbarch, pc);
 636             }
 637           CATCH (error, RETURN_MASK_ERROR)
 638             {
 639             }
 640           END_CATCH
 641
 642           insn.pc = pc;
 643           insn.size = size;
 644           insn.iclass = ftrace_classify_insn (gdbarch, pc);
 645
 646           ftrace_update_insns (end, &insn);
 647
 648           /* We're done once we pushed the instruction at the end.  */
 649           if (block->end == pc)
 650             break;
 651
 652           /* We can't continue if we fail to compute the size.  */
 653           if (size <= 0)
 654             {
 655               warning (_("Recorded trace may be incomplete around %s."),
 656                        core_addr_to_string_nz (pc));
 657
 658               /* Indicate the gap in the trace.  We just added INSN so we're
 659                  not at the beginning.  */
 660               end = ftrace_new_gap (end, BDE_BTS_INSN_SIZE);
 661               ngaps += 1;
 662
 663               break;
 664             }
 665
 666           pc += size;
 667
 668           /* Maintain the function level offset.
 669              For the last block, we do it here to not consider the last
 670              instruction.
 671              Since the last instruction corresponds to the current instruction
 672              and is not really part of the execution history, it shouldn't
 673              affect the level.  */
 674           if (blk == 0)
 675             level = min (level, end->level);
 676         }
 677     }
 678
 679   btinfo->begin = begin;
 680   btinfo->end = end;
 681   btinfo->ngaps = ngaps;
 682
 683   /* LEVEL is the minimal function level of all btrace function segments.
 684      Define the global level offset to -LEVEL so all function levels are
 685      normalized to start at zero.  */
 686   btinfo->level = -level;
 687 }
 688
 689 /* Compute the function branch trace from a block branch trace BTRACE for
 690    a thread given by BTINFO.  */
 691
 692 static void
 693 btrace_compute_ftrace (struct thread_info *tp, struct btrace_data *btrace)
 694 {
 695   DEBUG ("compute ftrace");
 696
 697   switch (btrace->format)
 698     {
 699     case BTRACE_FORMAT_NONE:
 700       return;
 701
 702     case BTRACE_FORMAT_BTS:
 703       btrace_compute_ftrace_bts (tp, &btrace->variant.bts);
 704       return;
 705     }
 706
 707   internal_error (__FILE__, __LINE__, _("Unkown branch trace format."));
 708 }
 709
 710 /* Add an entry for the current PC.  */
 711
 712 static void
 713 btrace_add_pc (struct thread_info *tp)
 714 {
 715   struct btrace_data btrace;
 716   struct btrace_block *block;
 717   struct regcache *regcache;
 718   struct cleanup *cleanup;
 719   CORE_ADDR pc;
 720
 721   regcache = get_thread_regcache (tp->ptid);
 722   pc = regcache_read_pc (regcache);
 723
 724   btrace_data_init (&btrace);
 725   btrace.format = BTRACE_FORMAT_BTS;
 726   btrace.variant.bts.blocks = NULL;
 727
 728   cleanup = make_cleanup_btrace_data (&btrace);
 729
 730   block = VEC_safe_push (btrace_block_s, btrace.variant.bts.blocks, NULL);
 731   block->begin = pc;
 732   block->end = pc;
 733
 734   btrace_compute_ftrace (tp, &btrace);
 735
 736   do_cleanups (cleanup);
 737 }
 738
 739 /* See btrace.h.  */
 740
 741 void
 742 btrace_enable (struct thread_info *tp, const struct btrace_config *conf)
 743 {
 744   if (tp->btrace.target != NULL)
 745     return;
 746
 747   if (!target_supports_btrace (conf->format))
 748     error (_("Target does not support branch tracing."));
 749
 750   DEBUG ("enable thread %d (%s)", tp->num, target_pid_to_str (tp->ptid));
 751
 752   tp->btrace.target = target_enable_btrace (tp->ptid, conf);
 753
 754   /* Add an entry for the current PC so we start tracing from where we
 755      enabled it.  */
 756   if (tp->btrace.target != NULL)
 757     btrace_add_pc (tp);
 758 }
 759
 760 /* See btrace.h.  */
 761
 762 const struct btrace_config *
 763 btrace_conf (const struct btrace_thread_info *btinfo)
 764 {
 765   if (btinfo->target == NULL)
 766     return NULL;
 767
 768   return target_btrace_conf (btinfo->target);
 769 }
 770
 771 /* See btrace.h.  */
 772
 773 void
 774 btrace_disable (struct thread_info *tp)
 775 {
 776   struct btrace_thread_info *btp = &tp->btrace;
 777   int errcode = 0;
 778
 779   if (btp->target == NULL)
 780     return;
 781
 782   DEBUG ("disable thread %d (%s)", tp->num, target_pid_to_str (tp->ptid));
 783
 784   target_disable_btrace (btp->target);
 785   btp->target = NULL;
 786
 787   btrace_clear (tp);
 788 }
 789
 790 /* See btrace.h.  */
 791
 792 void
 793 btrace_teardown (struct thread_info *tp)
 794 {
 795   struct btrace_thread_info *btp = &tp->btrace;
 796   int errcode = 0;
 797
 798   if (btp->target == NULL)
 799     return;
 800
 801   DEBUG ("teardown thread %d (%s)", tp->num, target_pid_to_str (tp->ptid));
 802
 803   target_teardown_btrace (btp->target);
 804   btp->target = NULL;
 805
 806   btrace_clear (tp);
 807 }
 808
 809 /* Stitch branch trace in BTS format.  */
 810
 811 static int
 812 btrace_stitch_bts (struct btrace_data_bts *btrace, struct thread_info *tp)
 813 {
 814   struct btrace_thread_info *btinfo;
 815   struct btrace_function *last_bfun;
 816   struct btrace_insn *last_insn;
 817   btrace_block_s *first_new_block;
 818
 819   btinfo = &tp->btrace;
 820   last_bfun = btinfo->end;
 821   gdb_assert (last_bfun != NULL);
 822   gdb_assert (!VEC_empty (btrace_block_s, btrace->blocks));
 823
 824   /* If the existing trace ends with a gap, we just glue the traces
 825      together.  We need to drop the last (i.e. chronologically first) block
 826      of the new trace,  though, since we can't fill in the start address.*/
 827   if (VEC_empty (btrace_insn_s, last_bfun->insn))
 828     {
 829       VEC_pop (btrace_block_s, btrace->blocks);
 830       return 0;
 831     }
 832
 833   /* Beware that block trace starts with the most recent block, so the
 834      chronologically first block in the new trace is the last block in
 835      the new trace's block vector.  */
 836   first_new_block = VEC_last (btrace_block_s, btrace->blocks);
 837   last_insn = VEC_last (btrace_insn_s, last_bfun->insn);
 838
 839   /* If the current PC at the end of the block is the same as in our current
 840      trace, there are two explanations:
 841        1. we executed the instruction and some branch brought us back.
 842        2. we have not made any progress.
 843      In the first case, the delta trace vector should contain at least two
 844      entries.
 845      In the second case, the delta trace vector should contain exactly one
 846      entry for the partial block containing the current PC.  Remove it.  */
 847   if (first_new_block->end == last_insn->pc
 848       && VEC_length (btrace_block_s, btrace->blocks) == 1)
 849     {
 850       VEC_pop (btrace_block_s, btrace->blocks);
 851       return 0;
 852     }
 853
 854   DEBUG ("stitching %s to %s", ftrace_print_insn_addr (last_insn),
 855          core_addr_to_string_nz (first_new_block->end));
 856
 857   /* Do a simple sanity check to make sure we don't accidentally end up
 858      with a bad block.  This should not occur in practice.  */
 859   if (first_new_block->end < last_insn->pc)
 860     {
 861       warning (_("Error while trying to read delta trace.  Falling back to "
 862                  "a full read."));
 863       return -1;
 864     }
 865
 866   /* We adjust the last block to start at the end of our current trace.  */
 867   gdb_assert (first_new_block->begin == 0);
 868   first_new_block->begin = last_insn->pc;
 869
 870   /* We simply pop the last insn so we can insert it again as part of
 871      the normal branch trace computation.
 872      Since instruction iterators are based on indices in the instructions
 873      vector, we don't leave any pointers dangling.  */
 874   DEBUG ("pruning insn at %s for stitching",
 875          ftrace_print_insn_addr (last_insn));
 876
 877   VEC_pop (btrace_insn_s, last_bfun->insn);
 878
 879   /* The instructions vector may become empty temporarily if this has
 880      been the only instruction in this function segment.
 881      This violates the invariant but will be remedied shortly by
 882      btrace_compute_ftrace when we add the new trace.  */
 883
 884   /* The only case where this would hurt is if the entire trace consisted
 885      of just that one instruction.  If we remove it, we might turn the now
 886      empty btrace function segment into a gap.  But we don't want gaps at
 887      the beginning.  To avoid this, we remove the entire old trace.  */
 888   if (last_bfun == btinfo->begin && VEC_empty (btrace_insn_s, last_bfun->insn))
 889     btrace_clear (tp);
 890
 891   return 0;
 892 }
 893
 894 /* Adjust the block trace in order to stitch old and new trace together.
 895    BTRACE is the new delta trace between the last and the current stop.
 896    TP is the traced thread.
 897    May modifx BTRACE as well as the existing trace in TP.
 898    Return 0 on success, -1 otherwise.  */
 899
 900 static int
 901 btrace_stitch_trace (struct btrace_data *btrace, struct thread_info *tp)
 902 {
 903   /* If we don't have trace, there's nothing to do.  */
 904   if (btrace_data_empty (btrace))
 905     return 0;
 906
 907   switch (btrace->format)
 908     {
 909     case BTRACE_FORMAT_NONE:
 910       return 0;
 911
 912     case BTRACE_FORMAT_BTS:
 913       return btrace_stitch_bts (&btrace->variant.bts, tp);
 914     }
 915
 916   internal_error (__FILE__, __LINE__, _("Unkown branch trace format."));
 917 }
 918
 919 /* Clear the branch trace histories in BTINFO.  */
 920
 921 static void
 922 btrace_clear_history (struct btrace_thread_info *btinfo)
 923 {
 924   xfree (btinfo->insn_history);
 925   xfree (btinfo->call_history);
 926   xfree (btinfo->replay);
 927
 928   btinfo->insn_history = NULL;
 929   btinfo->call_history = NULL;
 930   btinfo->replay = NULL;
 931 }
 932
 933 /* See btrace.h.  */
 934
 935 void
 936 btrace_fetch (struct thread_info *tp)
 937 {
 938   struct btrace_thread_info *btinfo;
 939   struct btrace_target_info *tinfo;
 940   struct btrace_data btrace;
 941   struct cleanup *cleanup;
 942   int errcode;
 943
 944   DEBUG ("fetch thread %d (%s)", tp->num, target_pid_to_str (tp->ptid));
 945
 946   btinfo = &tp->btrace;
 947   tinfo = btinfo->target;
 948   if (tinfo == NULL)
 949     return;
 950
 951   /* There's no way we could get new trace while replaying.
 952      On the other hand, delta trace would return a partial record with the
 953      current PC, which is the replay PC, not the last PC, as expected.  */
 954   if (btinfo->replay != NULL)
 955     return;
 956
 957   btrace_data_init (&btrace);
 958   cleanup = make_cleanup_btrace_data (&btrace);
 959
 960   /* Let's first try to extend the trace we already have.  */
 961   if (btinfo->end != NULL)
 962     {
 963       errcode = target_read_btrace (&btrace, tinfo, BTRACE_READ_DELTA);
 964       if (errcode == 0)
 965         {
 966           /* Success.  Let's try to stitch the traces together.  */
 967           errcode = btrace_stitch_trace (&btrace, tp);
 968         }
 969       else
 970         {
 971           /* We failed to read delta trace.  Let's try to read new trace.  */
 972           errcode = target_read_btrace (&btrace, tinfo, BTRACE_READ_NEW);
 973
 974           /* If we got any new trace, discard what we have.  */
 975           if (errcode == 0 && !btrace_data_empty (&btrace))
 976             btrace_clear (tp);
 977         }
 978
 979       /* If we were not able to read the trace, we start over.  */
 980       if (errcode != 0)
 981         {
 982           btrace_clear (tp);
 983           errcode = target_read_btrace (&btrace, tinfo, BTRACE_READ_ALL);
 984         }
 985     }
 986   else
 987     errcode = target_read_btrace (&btrace, tinfo, BTRACE_READ_ALL);
 988
 989   /* If we were not able to read the branch trace, signal an error.  */
 990   if (errcode != 0)
 991     error (_("Failed to read branch trace."));
 992
 993   /* Compute the trace, provided we have any.  */
 994   if (!btrace_data_empty (&btrace))
 995     {
 996       btrace_clear_history (btinfo);
 997       btrace_compute_ftrace (tp, &btrace);
 998     }
 999
1000   do_cleanups (cleanup);
1001 }
1002
1003 /* See btrace.h.  */
1004
1005 void
1006 btrace_clear (struct thread_info *tp)
1007 {
1008   struct btrace_thread_info *btinfo;
1009   struct btrace_function *it, *trash;
1010
1011   DEBUG ("clear thread %d (%s)", tp->num, target_pid_to_str (tp->ptid));
1012
1013   /* Make sure btrace frames that may hold a pointer into the branch
1014      trace data are destroyed.  */
1015   reinit_frame_cache ();
1016
1017   btinfo = &tp->btrace;
1018
1019   it = btinfo->begin;
1020   while (it != NULL)
1021     {
1022       trash = it;
1023       it = it->flow.next;
1024
1025       xfree (trash);
1026     }
1027
1028   btinfo->begin = NULL;
1029   btinfo->end = NULL;
1030   btinfo->ngaps = 0;
1031
1032   btrace_clear_history (btinfo);
1033 }
1034
1035 /* See btrace.h.  */
1036
1037 void
1038 btrace_free_objfile (struct objfile *objfile)
1039 {
1040   struct thread_info *tp;
1041
1042   DEBUG ("free objfile");
1043
1044   ALL_NON_EXITED_THREADS (tp)
1045     btrace_clear (tp);
1046 }
1047
1048 #if defined (HAVE_LIBEXPAT)
1049
1050 /* Check the btrace document version.  */
1051
1052 static void
1053 check_xml_btrace_version (struct gdb_xml_parser *parser,
1054                           const struct gdb_xml_element *element,
1055                           void *user_data, VEC (gdb_xml_value_s) *attributes)
1056 {
1057   const char *version = xml_find_attribute (attributes, "version")->value;
1058
1059   if (strcmp (version, "1.0") != 0)
1060     gdb_xml_error (parser, _("Unsupported btrace version: \"%s\""), version);
1061 }
1062
1063 /* Parse a btrace "block" xml record.  */
1064
1065 static void
1066 parse_xml_btrace_block (struct gdb_xml_parser *parser,
1067                         const struct gdb_xml_element *element,
1068                         void *user_data, VEC (gdb_xml_value_s) *attributes)
1069 {
1070   struct btrace_data *btrace;
1071   struct btrace_block *block;
1072   ULONGEST *begin, *end;
1073
1074   btrace = user_data;
1075
1076   switch (btrace->format)
1077     {
1078     case BTRACE_FORMAT_BTS:
1079       break;
1080
1081     case BTRACE_FORMAT_NONE:
1082       btrace->format = BTRACE_FORMAT_BTS;
1083       btrace->variant.bts.blocks = NULL;
1084       break;
1085
1086     default:
1087       gdb_xml_error (parser, _("Btrace format error."));
1088     }
1089
1090   begin = xml_find_attribute (attributes, "begin")->value;
1091   end = xml_find_attribute (attributes, "end")->value;
1092
1093   block = VEC_safe_push (btrace_block_s, btrace->variant.bts.blocks, NULL);
1094   block->begin = *begin;
1095   block->end = *end;
1096 }
1097
1098 static const struct gdb_xml_attribute block_attributes[] = {
1099   { "begin", GDB_XML_AF_NONE, gdb_xml_parse_attr_ulongest, NULL },
1100   { "end", GDB_XML_AF_NONE, gdb_xml_parse_attr_ulongest, NULL },
1101   { NULL, GDB_XML_AF_NONE, NULL, NULL }
1102 };
1103
1104 static const struct gdb_xml_attribute btrace_attributes[] = {
1105   { "version", GDB_XML_AF_NONE, NULL, NULL },
1106   { NULL, GDB_XML_AF_NONE, NULL, NULL }
1107 };
1108
1109 static const struct gdb_xml_element btrace_children[] = {
1110   { "block", block_attributes, NULL,
1111     GDB_XML_EF_REPEATABLE | GDB_XML_EF_OPTIONAL, parse_xml_btrace_block, NULL },
1112   { NULL, NULL, NULL, GDB_XML_EF_NONE, NULL, NULL }
1113 };
1114
1115 static const struct gdb_xml_element btrace_elements[] = {
1116   { "btrace", btrace_attributes, btrace_children, GDB_XML_EF_NONE,
1117     check_xml_btrace_version, NULL },
1118   { NULL, NULL, NULL, GDB_XML_EF_NONE, NULL, NULL }
1119 };
1120
1121 #endif /* defined (HAVE_LIBEXPAT) */
1122
1123 /* See btrace.h.  */
1124
1125 void
1126 parse_xml_btrace (struct btrace_data *btrace, const char *buffer)
1127 {
1128   struct cleanup *cleanup;
1129   int errcode;
1130
1131 #if defined (HAVE_LIBEXPAT)
1132
1133   btrace->format = BTRACE_FORMAT_NONE;
1134
1135   cleanup = make_cleanup_btrace_data (btrace);
1136   errcode = gdb_xml_parse_quick (_("btrace"), "btrace.dtd", btrace_elements,
1137                                  buffer, btrace);
1138   if (errcode != 0)
1139     error (_("Error parsing branch trace."));
1140
1141   /* Keep parse results.  */
1142   discard_cleanups (cleanup);
1143
1144 #else  /* !defined (HAVE_LIBEXPAT) */
1145
1146   error (_("Cannot process branch trace.  XML parsing is not supported."));
1147
1148 #endif  /* !defined (HAVE_LIBEXPAT) */
1149 }
1150
1151 #if defined (HAVE_LIBEXPAT)
1152
1153 /* Parse a btrace-conf "bts" xml record.  */
1154
1155 static void
1156 parse_xml_btrace_conf_bts (struct gdb_xml_parser *parser,
1157                           const struct gdb_xml_element *element,
1158                           void *user_data, VEC (gdb_xml_value_s) *attributes)
1159 {
1160   struct btrace_config *conf;
1161   struct gdb_xml_value *size;
1162
1163   conf = user_data;
1164   conf->format = BTRACE_FORMAT_BTS;
1165   conf->bts.size = 0;
1166
1167   size = xml_find_attribute (attributes, "size");
1168   if (size != NULL)
1169     conf->bts.size = (unsigned int) * (ULONGEST *) size->value;
1170 }
1171
1172 static const struct gdb_xml_attribute btrace_conf_bts_attributes[] = {
1173   { "size", GDB_XML_AF_OPTIONAL, gdb_xml_parse_attr_ulongest, NULL },
1174   { NULL, GDB_XML_AF_NONE, NULL, NULL }
1175 };
1176
1177 static const struct gdb_xml_element btrace_conf_children[] = {
1178   { "bts", btrace_conf_bts_attributes, NULL, GDB_XML_EF_OPTIONAL,
1179     parse_xml_btrace_conf_bts, NULL },
1180   { NULL, NULL, NULL, GDB_XML_EF_NONE, NULL, NULL }
1181 };
1182
1183 static const struct gdb_xml_attribute btrace_conf_attributes[] = {
1184   { "version", GDB_XML_AF_NONE, NULL, NULL },
1185   { NULL, GDB_XML_AF_NONE, NULL, NULL }
1186 };
1187
1188 static const struct gdb_xml_element btrace_conf_elements[] = {
1189   { "btrace-conf", btrace_conf_attributes, btrace_conf_children,
1190     GDB_XML_EF_NONE, NULL, NULL },
1191   { NULL, NULL, NULL, GDB_XML_EF_NONE, NULL, NULL }
1192 };
1193
1194 #endif /* defined (HAVE_LIBEXPAT) */
1195
1196 /* See btrace.h.  */
1197
1198 void
1199 parse_xml_btrace_conf (struct btrace_config *conf, const char *xml)
1200 {
1201   int errcode;
1202
1203 #if defined (HAVE_LIBEXPAT)
1204
1205   errcode = gdb_xml_parse_quick (_("btrace-conf"), "btrace-conf.dtd",
1206                                  btrace_conf_elements, xml, conf);
1207   if (errcode != 0)
1208     error (_("Error parsing branch trace configuration."));
1209
1210 #else  /* !defined (HAVE_LIBEXPAT) */
1211
1212   error (_("XML parsing is not supported."));
1213
1214 #endif  /* !defined (HAVE_LIBEXPAT) */
1215 }
1216
1217 /* See btrace.h.  */
1218
1219 const struct btrace_insn *
1220 btrace_insn_get (const struct btrace_insn_iterator *it)
1221 {
1222   const struct btrace_function *bfun;
1223   unsigned int index, end;
1224
1225   index = it->index;
1226   bfun = it->function;
1227
1228   /* Check if the iterator points to a gap in the trace.  */
1229   if (bfun->errcode != 0)
1230     return NULL;
1231
1232   /* The index is within the bounds of this function's instruction vector.  */
1233   end = VEC_length (btrace_insn_s, bfun->insn);
1234   gdb_assert (0 < end);
1235   gdb_assert (index < end);
1236
1237   return VEC_index (btrace_insn_s, bfun->insn, index);
1238 }
1239
1240 /* See btrace.h.  */
1241
1242 unsigned int
1243 btrace_insn_number (const struct btrace_insn_iterator *it)
1244 {
1245   const struct btrace_function *bfun;
1246
1247   bfun = it->function;
1248
1249   /* Return zero if the iterator points to a gap in the trace.  */
1250   if (bfun->errcode != 0)
1251     return 0;
1252
1253   return bfun->insn_offset + it->index;
1254 }
1255
1256 /* See btrace.h.  */
1257
1258 void
1259 btrace_insn_begin (struct btrace_insn_iterator *it,
1260                    const struct btrace_thread_info *btinfo)
1261 {
1262   const struct btrace_function *bfun;
1263
1264   bfun = btinfo->begin;
1265   if (bfun == NULL)
1266     error (_("No trace."));
1267
1268   it->function = bfun;
1269   it->index = 0;
1270 }
1271
1272 /* See btrace.h.  */
1273
1274 void
1275 btrace_insn_end (struct btrace_insn_iterator *it,
1276                  const struct btrace_thread_info *btinfo)
1277 {
1278   const struct btrace_function *bfun;
1279   unsigned int length;
1280
1281   bfun = btinfo->end;
1282   if (bfun == NULL)
1283     error (_("No trace."));
1284
1285   length = VEC_length (btrace_insn_s, bfun->insn);
1286
1287   /* The last function may either be a gap or it contains the current
1288      instruction, which is one past the end of the execution trace; ignore
1289      it.  */
1290   if (length > 0)
1291     length -= 1;
1292
1293   it->function = bfun;
1294   it->index = length;
1295 }
1296
1297 /* See btrace.h.  */
1298
1299 unsigned int
1300 btrace_insn_next (struct btrace_insn_iterator *it, unsigned int stride)
1301 {
1302   const struct btrace_function *bfun;
1303   unsigned int index, steps;
1304
1305   bfun = it->function;
1306   steps = 0;
1307   index = it->index;
1308
1309   while (stride != 0)
1310     {
1311       unsigned int end, space, adv;
1312
1313       end = VEC_length (btrace_insn_s, bfun->insn);
1314
1315       /* An empty function segment represents a gap in the trace.  We count
1316          it as one instruction.  */
1317       if (end == 0)
1318         {
1319           const struct btrace_function *next;
1320
1321           next = bfun->flow.next;
1322           if (next == NULL)
1323             break;
1324
1325           stride -= 1;
1326           steps += 1;
1327
1328           bfun = next;
1329           index = 0;
1330
1331           continue;
1332         }
1333
1334       gdb_assert (0 < end);
1335       gdb_assert (index < end);
1336
1337       /* Compute the number of instructions remaining in this segment.  */
1338       space = end - index;
1339
1340       /* Advance the iterator as far as possible within this segment.  */
1341       adv = min (space, stride);
1342       stride -= adv;
1343       index += adv;
1344       steps += adv;
1345
1346       /* Move to the next function if we're at the end of this one.  */
1347       if (index == end)
1348         {
1349           const struct btrace_function *next;
1350
1351           next = bfun->flow.next;
1352           if (next == NULL)
1353             {
1354               /* We stepped past the last function.
1355
1356                  Let's adjust the index to point to the last instruction in
1357                  the previous function.  */
1358               index -= 1;
1359               steps -= 1;
1360               break;
1361             }
1362
1363           /* We now point to the first instruction in the new function.  */
1364           bfun = next;
1365           index = 0;
1366         }
1367
1368       /* We did make progress.  */
1369       gdb_assert (adv > 0);
1370     }
1371
1372   /* Update the iterator.  */
1373   it->function = bfun;
1374   it->index = index;
1375
1376   return steps;
1377 }
1378
1379 /* See btrace.h.  */
1380
1381 unsigned int
1382 btrace_insn_prev (struct btrace_insn_iterator *it, unsigned int stride)
1383 {
1384   const struct btrace_function *bfun;
1385   unsigned int index, steps;
1386
1387   bfun = it->function;
1388   steps = 0;
1389   index = it->index;
1390
1391   while (stride != 0)
1392     {
1393       unsigned int adv;
1394
1395       /* Move to the previous function if we're at the start of this one.  */
1396       if (index == 0)
1397         {
1398           const struct btrace_function *prev;
1399
1400           prev = bfun->flow.prev;
1401           if (prev == NULL)
1402             break;
1403
1404           /* We point to one after the last instruction in the new function.  */
1405           bfun = prev;
1406           index = VEC_length (btrace_insn_s, bfun->insn);
1407
1408           /* An empty function segment represents a gap in the trace.  We count
1409              it as one instruction.  */
1410           if (index == 0)
1411             {
1412               stride -= 1;
1413               steps += 1;
1414
1415               continue;
1416             }
1417         }
1418
1419       /* Advance the iterator as far as possible within this segment.  */
1420       adv = min (index, stride);
1421
1422       stride -= adv;
1423       index -= adv;
1424       steps += adv;
1425
1426       /* We did make progress.  */
1427       gdb_assert (adv > 0);
1428     }
1429
1430   /* Update the iterator.  */
1431   it->function = bfun;
1432   it->index = index;
1433
1434   return steps;
1435 }
1436
1437 /* See btrace.h.  */
1438
1439 int
1440 btrace_insn_cmp (const struct btrace_insn_iterator *lhs,
1441                  const struct btrace_insn_iterator *rhs)
1442 {
1443   unsigned int lnum, rnum;
1444
1445   lnum = btrace_insn_number (lhs);
1446   rnum = btrace_insn_number (rhs);
1447
1448   /* A gap has an instruction number of zero.  Things are getting more
1449      complicated if gaps are involved.
1450
1451      We take the instruction number offset from the iterator's function.
1452      This is the number of the first instruction after the gap.
1453
1454      This is OK as long as both lhs and rhs point to gaps.  If only one of
1455      them does, we need to adjust the number based on the other's regular
1456      instruction number.  Otherwise, a gap might compare equal to an
1457      instruction.  */
1458
1459   if (lnum == 0 && rnum == 0)
1460     {
1461       lnum = lhs->function->insn_offset;
1462       rnum = rhs->function->insn_offset;
1463     }
1464   else if (lnum == 0)
1465     {
1466       lnum = lhs->function->insn_offset;
1467
1468       if (lnum == rnum)
1469         lnum -= 1;
1470     }
1471   else if (rnum == 0)
1472     {
1473       rnum = rhs->function->insn_offset;
1474
1475       if (rnum == lnum)
1476         rnum -= 1;
1477     }
1478
1479   return (int) (lnum - rnum);
1480 }
1481
1482 /* See btrace.h.  */
1483
1484 int
1485 btrace_find_insn_by_number (struct btrace_insn_iterator *it,
1486                             const struct btrace_thread_info *btinfo,
1487                             unsigned int number)
1488 {
1489   const struct btrace_function *bfun;
1490   unsigned int end, length;
1491
1492   for (bfun = btinfo->end; bfun != NULL; bfun = bfun->flow.prev)
1493     {
1494       /* Skip gaps. */
1495       if (bfun->errcode != 0)
1496         continue;
1497
1498       if (bfun->insn_offset <= number)
1499         break;
1500     }
1501
1502   if (bfun == NULL)
1503     return 0;
1504
1505   length = VEC_length (btrace_insn_s, bfun->insn);
1506   gdb_assert (length > 0);
1507
1508   end = bfun->insn_offset + length;
1509   if (end <= number)
1510     return 0;
1511
1512   it->function = bfun;
1513   it->index = number - bfun->insn_offset;
1514
1515   return 1;
1516 }
1517
1518 /* See btrace.h.  */
1519
1520 const struct btrace_function *
1521 btrace_call_get (const struct btrace_call_iterator *it)
1522 {
1523   return it->function;
1524 }
1525
1526 /* See btrace.h.  */
1527
1528 unsigned int
1529 btrace_call_number (const struct btrace_call_iterator *it)
1530 {
1531   const struct btrace_thread_info *btinfo;
1532   const struct btrace_function *bfun;
1533   unsigned int insns;
1534
1535   btinfo = it->btinfo;
1536   bfun = it->function;
1537   if (bfun != NULL)
1538     return bfun->number;
1539
1540   /* For the end iterator, i.e. bfun == NULL, we return one more than the
1541      number of the last function.  */
1542   bfun = btinfo->end;
1543   insns = VEC_length (btrace_insn_s, bfun->insn);
1544
1545   /* If the function contains only a single instruction (i.e. the current
1546      instruction), it will be skipped and its number is already the number
1547      we seek.  */
1548   if (insns == 1)
1549     return bfun->number;
1550
1551   /* Otherwise, return one more than the number of the last function.  */
1552   return bfun->number + 1;
1553 }
1554
1555 /* See btrace.h.  */
1556
1557 void
1558 btrace_call_begin (struct btrace_call_iterator *it,
1559                    const struct btrace_thread_info *btinfo)
1560 {
1561   const struct btrace_function *bfun;
1562
1563   bfun = btinfo->begin;
1564   if (bfun == NULL)
1565     error (_("No trace."));
1566
1567   it->btinfo = btinfo;
1568   it->function = bfun;
1569 }
1570
1571 /* See btrace.h.  */
1572
1573 void
1574 btrace_call_end (struct btrace_call_iterator *it,
1575                  const struct btrace_thread_info *btinfo)
1576 {
1577   const struct btrace_function *bfun;
1578
1579   bfun = btinfo->end;
1580   if (bfun == NULL)
1581     error (_("No trace."));
1582
1583   it->btinfo = btinfo;
1584   it->function = NULL;
1585 }
1586
1587 /* See btrace.h.  */
1588
1589 unsigned int
1590 btrace_call_next (struct btrace_call_iterator *it, unsigned int stride)
1591 {
1592   const struct btrace_function *bfun;
1593   unsigned int steps;
1594
1595   bfun = it->function;
1596   steps = 0;
1597   while (bfun != NULL)
1598     {
1599       const struct btrace_function *next;
1600       unsigned int insns;
1601
1602       next = bfun->flow.next;
1603       if (next == NULL)
1604         {
1605           /* Ignore the last function if it only contains a single
1606              (i.e. the current) instruction.  */
1607           insns = VEC_length (btrace_insn_s, bfun->insn);
1608           if (insns == 1)
1609             steps -= 1;
1610         }
1611
1612       if (stride == steps)
1613         break;
1614
1615       bfun = next;
1616       steps += 1;
1617     }
1618
1619   it->function = bfun;
1620   return steps;
1621 }
1622
1623 /* See btrace.h.  */
1624
1625 unsigned int
1626 btrace_call_prev (struct btrace_call_iterator *it, unsigned int stride)
1627 {
1628   const struct btrace_thread_info *btinfo;
1629   const struct btrace_function *bfun;
1630   unsigned int steps;
1631
1632   bfun = it->function;
1633   steps = 0;
1634
1635   if (bfun == NULL)
1636     {
1637       unsigned int insns;
1638
1639       btinfo = it->btinfo;
1640       bfun = btinfo->end;
1641       if (bfun == NULL)
1642         return 0;
1643
1644       /* Ignore the last function if it only contains a single
1645          (i.e. the current) instruction.  */
1646       insns = VEC_length (btrace_insn_s, bfun->insn);
1647       if (insns == 1)
1648         bfun = bfun->flow.prev;
1649
1650       if (bfun == NULL)
1651         return 0;
1652
1653       steps += 1;
1654     }
1655
1656   while (steps < stride)
1657     {
1658       const struct btrace_function *prev;
1659
1660       prev = bfun->flow.prev;
1661       if (prev == NULL)
1662         break;
1663
1664       bfun = prev;
1665       steps += 1;
1666     }
1667
1668   it->function = bfun;
1669   return steps;
1670 }
1671
1672 /* See btrace.h.  */
1673
1674 int
1675 btrace_call_cmp (const struct btrace_call_iterator *lhs,
1676                  const struct btrace_call_iterator *rhs)
1677 {
1678   unsigned int lnum, rnum;
1679
1680   lnum = btrace_call_number (lhs);
1681   rnum = btrace_call_number (rhs);
1682
1683   return (int) (lnum - rnum);
1684 }
1685
1686 /* See btrace.h.  */
1687
1688 int
1689 btrace_find_call_by_number (struct btrace_call_iterator *it,
1690                             const struct btrace_thread_info *btinfo,
1691                             unsigned int number)
1692 {
1693   const struct btrace_function *bfun;
1694
1695   for (bfun = btinfo->end; bfun != NULL; bfun = bfun->flow.prev)
1696     {
1697       unsigned int bnum;
1698
1699       bnum = bfun->number;
1700       if (number == bnum)
1701         {
1702           it->btinfo = btinfo;
1703           it->function = bfun;
1704           return 1;
1705         }
1706
1707       /* Functions are ordered and numbered consecutively.  We could bail out
1708          earlier.  On the other hand, it is very unlikely that we search for
1709          a nonexistent function.  */
1710   }
1711
1712   return 0;
1713 }
1714
1715 /* See btrace.h.  */
1716
1717 void
1718 btrace_set_insn_history (struct btrace_thread_info *btinfo,
1719                          const struct btrace_insn_iterator *begin,
1720                          const struct btrace_insn_iterator *end)
1721 {
1722   if (btinfo->insn_history == NULL)
1723     btinfo->insn_history = xzalloc (sizeof (*btinfo->insn_history));
1724
1725   btinfo->insn_history->begin = *begin;
1726   btinfo->insn_history->end = *end;
1727 }
1728
1729 /* See btrace.h.  */
1730
1731 void
1732 btrace_set_call_history (struct btrace_thread_info *btinfo,
1733                          const struct btrace_call_iterator *begin,
1734                          const struct btrace_call_iterator *end)
1735 {
1736   gdb_assert (begin->btinfo == end->btinfo);
1737
1738   if (btinfo->call_history == NULL)
1739     btinfo->call_history = xzalloc (sizeof (*btinfo->call_history));
1740
1741   btinfo->call_history->begin = *begin;
1742   btinfo->call_history->end = *end;
1743 }
1744
1745 /* See btrace.h.  */
1746
1747 int
1748 btrace_is_replaying (struct thread_info *tp)
1749 {
1750   return tp->btrace.replay != NULL;
1751 }
1752
1753 /* See btrace.h.  */
1754
1755 int
1756 btrace_is_empty (struct thread_info *tp)
1757 {
1758   struct btrace_insn_iterator begin, end;
1759   struct btrace_thread_info *btinfo;
1760
1761   btinfo = &tp->btrace;
1762
1763   if (btinfo->begin == NULL)
1764     return 1;
1765
1766   btrace_insn_begin (&begin, btinfo);
1767   btrace_insn_end (&end, btinfo);
1768
1769   return btrace_insn_cmp (&begin, &end) == 0;
1770 }
1771
1772 /* Forward the cleanup request.  */
1773
1774 static void
1775 do_btrace_data_cleanup (void *arg)
1776 {
1777   btrace_data_fini (arg);
1778 }
1779
1780 /* See btrace.h.  */
1781
1782 struct cleanup *
1783 make_cleanup_btrace_data (struct btrace_data *data)
1784 {
1785   return make_cleanup (do_btrace_data_cleanup, data);
1786 }