gdb/btrace.c

   1 /* Branch trace support for GDB, the GNU debugger.
   2
   3    Copyright (C) 2013-2014 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 "btrace.h"
  23 #include "gdbthread.h"
  24 #include "exceptions.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 (sym->symtab);
  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 lbegin, lend, level;
 109
 110   fun = ftrace_print_function_name (bfun);
 111   file = ftrace_print_filename (bfun);
 112   level = bfun->level;
 113
 114   lbegin = bfun->lbegin;
 115   lend = bfun->lend;
 116
 117   ibegin = bfun->insn_offset;
 118   iend = ibegin + VEC_length (btrace_insn_s, bfun->insn);
 119
 120   DEBUG_FTRACE ("%s: fun = %s, file = %s, level = %d, lines = [%d; %d], "
 121                 "insn = [%u; %u)", prefix, fun, file, level, lbegin, lend,
 122                 ibegin, iend);
 123 }
 124
 125 /* Return non-zero if BFUN does not match MFUN and FUN,
 126    return zero otherwise.  */
 127
 128 static int
 129 ftrace_function_switched (const struct btrace_function *bfun,
 130                           const struct minimal_symbol *mfun,
 131                           const struct symbol *fun)
 132 {
 133   struct minimal_symbol *msym;
 134   struct symbol *sym;
 135
 136   msym = bfun->msym;
 137   sym = bfun->sym;
 138
 139   /* If the minimal symbol changed, we certainly switched functions.  */
 140   if (mfun != NULL && msym != NULL
 141       && strcmp (MSYMBOL_LINKAGE_NAME (mfun), MSYMBOL_LINKAGE_NAME (msym)) != 0)
 142     return 1;
 143
 144   /* If the symbol changed, we certainly switched functions.  */
 145   if (fun != NULL && sym != NULL)
 146     {
 147       const char *bfname, *fname;
 148
 149       /* Check the function name.  */
 150       if (strcmp (SYMBOL_LINKAGE_NAME (fun), SYMBOL_LINKAGE_NAME (sym)) != 0)
 151         return 1;
 152
 153       /* Check the location of those functions, as well.  */
 154       bfname = symtab_to_fullname (sym->symtab);
 155       fname = symtab_to_fullname (fun->symtab);
 156       if (filename_cmp (fname, bfname) != 0)
 157         return 1;
 158     }
 159
 160   /* If we lost symbol information, we switched functions.  */
 161   if (!(msym == NULL && sym == NULL) && mfun == NULL && fun == NULL)
 162     return 1;
 163
 164   /* If we gained symbol information, we switched functions.  */
 165   if (msym == NULL && sym == NULL && !(mfun == NULL && fun == NULL))
 166     return 1;
 167
 168   return 0;
 169 }
 170
 171 /* Return non-zero if we should skip this file when generating the function
 172    call history, zero otherwise.
 173    We would want to do that if, say, a macro that is defined in another file
 174    is expanded in this function.  */
 175
 176 static int
 177 ftrace_skip_file (const struct btrace_function *bfun, const char *fullname)
 178 {
 179   struct symbol *sym;
 180   const char *bfile;
 181
 182   sym = bfun->sym;
 183   if (sym == NULL)
 184     return 1;
 185
 186   bfile = symtab_to_fullname (sym->symtab);
 187
 188   return (filename_cmp (bfile, fullname) != 0);
 189 }
 190
 191 /* Allocate and initialize a new branch trace function segment.
 192    PREV is the chronologically preceding function segment.
 193    MFUN and FUN are the symbol information we have for this function.  */
 194
 195 static struct btrace_function *
 196 ftrace_new_function (struct btrace_function *prev,
 197                      struct minimal_symbol *mfun,
 198                      struct symbol *fun)
 199 {
 200   struct btrace_function *bfun;
 201
 202   bfun = xzalloc (sizeof (*bfun));
 203
 204   bfun->msym = mfun;
 205   bfun->sym = fun;
 206   bfun->flow.prev = prev;
 207
 208   /* We start with the identities of min and max, respectively.  */
 209   bfun->lbegin = INT_MAX;
 210   bfun->lend = INT_MIN;
 211
 212   if (prev == NULL)
 213     {
 214       /* Start counting at one.  */
 215       bfun->number = 1;
 216       bfun->insn_offset = 1;
 217     }
 218   else
 219     {
 220       gdb_assert (prev->flow.next == NULL);
 221       prev->flow.next = bfun;
 222
 223       bfun->number = prev->number + 1;
 224       bfun->insn_offset = (prev->insn_offset
 225                            + VEC_length (btrace_insn_s, prev->insn));
 226     }
 227
 228   return bfun;
 229 }
 230
 231 /* Update the UP field of a function segment.  */
 232
 233 static void
 234 ftrace_update_caller (struct btrace_function *bfun,
 235                       struct btrace_function *caller,
 236                       enum btrace_function_flag flags)
 237 {
 238   if (bfun->up != NULL)
 239     ftrace_debug (bfun, "updating caller");
 240
 241   bfun->up = caller;
 242   bfun->flags = flags;
 243
 244   ftrace_debug (bfun, "set caller");
 245 }
 246
 247 /* Fix up the caller for all segments of a function.  */
 248
 249 static void
 250 ftrace_fixup_caller (struct btrace_function *bfun,
 251                      struct btrace_function *caller,
 252                      enum btrace_function_flag flags)
 253 {
 254   struct btrace_function *prev, *next;
 255
 256   ftrace_update_caller (bfun, caller, flags);
 257
 258   /* Update all function segments belonging to the same function.  */
 259   for (prev = bfun->segment.prev; prev != NULL; prev = prev->segment.prev)
 260     ftrace_update_caller (prev, caller, flags);
 261
 262   for (next = bfun->segment.next; next != NULL; next = next->segment.next)
 263     ftrace_update_caller (next, caller, flags);
 264 }
 265
 266 /* Add a new function segment for a call.
 267    CALLER is the chronologically preceding function segment.
 268    MFUN and FUN are the symbol information we have for this function.  */
 269
 270 static struct btrace_function *
 271 ftrace_new_call (struct btrace_function *caller,
 272                  struct minimal_symbol *mfun,
 273                  struct symbol *fun)
 274 {
 275   struct btrace_function *bfun;
 276
 277   bfun = ftrace_new_function (caller, mfun, fun);
 278   bfun->up = caller;
 279   bfun->level = caller->level + 1;
 280
 281   ftrace_debug (bfun, "new call");
 282
 283   return bfun;
 284 }
 285
 286 /* Add a new function segment for a tail call.
 287    CALLER is the chronologically preceding function segment.
 288    MFUN and FUN are the symbol information we have for this function.  */
 289
 290 static struct btrace_function *
 291 ftrace_new_tailcall (struct btrace_function *caller,
 292                      struct minimal_symbol *mfun,
 293                      struct symbol *fun)
 294 {
 295   struct btrace_function *bfun;
 296
 297   bfun = ftrace_new_function (caller, mfun, fun);
 298   bfun->up = caller;
 299   bfun->level = caller->level + 1;
 300   bfun->flags |= BFUN_UP_LINKS_TO_TAILCALL;
 301
 302   ftrace_debug (bfun, "new tail call");
 303
 304   return bfun;
 305 }
 306
 307 /* Find the innermost caller in the back trace of BFUN with MFUN/FUN
 308    symbol information.  */
 309
 310 static struct btrace_function *
 311 ftrace_find_caller (struct btrace_function *bfun,
 312                     struct minimal_symbol *mfun,
 313                     struct symbol *fun)
 314 {
 315   for (; bfun != NULL; bfun = bfun->up)
 316     {
 317       /* Skip functions with incompatible symbol information.  */
 318       if (ftrace_function_switched (bfun, mfun, fun))
 319         continue;
 320
 321       /* This is the function segment we're looking for.  */
 322       break;
 323     }
 324
 325   return bfun;
 326 }
 327
 328 /* Find the innermost caller in the back trace of BFUN, skipping all
 329    function segments that do not end with a call instruction (e.g.
 330    tail calls ending with a jump).  */
 331
 332 static struct btrace_function *
 333 ftrace_find_call (struct gdbarch *gdbarch, struct btrace_function *bfun)
 334 {
 335   for (; bfun != NULL; bfun = bfun->up)
 336     {
 337       struct btrace_insn *last;
 338       CORE_ADDR pc;
 339
 340       /* We do not allow empty function segments.  */
 341       gdb_assert (!VEC_empty (btrace_insn_s, bfun->insn));
 342
 343       last = VEC_last (btrace_insn_s, bfun->insn);
 344       pc = last->pc;
 345
 346       if (gdbarch_insn_is_call (gdbarch, pc))
 347         break;
 348     }
 349
 350   return bfun;
 351 }
 352
 353 /* Add a continuation segment for a function into which we return.
 354    PREV is the chronologically preceding function segment.
 355    MFUN and FUN are the symbol information we have for this function.  */
 356
 357 static struct btrace_function *
 358 ftrace_new_return (struct gdbarch *gdbarch,
 359                    struct btrace_function *prev,
 360                    struct minimal_symbol *mfun,
 361                    struct symbol *fun)
 362 {
 363   struct btrace_function *bfun, *caller;
 364
 365   bfun = ftrace_new_function (prev, mfun, fun);
 366
 367   /* It is important to start at PREV's caller.  Otherwise, we might find
 368      PREV itself, if PREV is a recursive function.  */
 369   caller = ftrace_find_caller (prev->up, mfun, fun);
 370   if (caller != NULL)
 371     {
 372       /* The caller of PREV is the preceding btrace function segment in this
 373          function instance.  */
 374       gdb_assert (caller->segment.next == NULL);
 375
 376       caller->segment.next = bfun;
 377       bfun->segment.prev = caller;
 378
 379       /* Maintain the function level.  */
 380       bfun->level = caller->level;
 381
 382       /* Maintain the call stack.  */
 383       bfun->up = caller->up;
 384       bfun->flags = caller->flags;
 385
 386       ftrace_debug (bfun, "new return");
 387     }
 388   else
 389     {
 390       /* We did not find a caller.  This could mean that something went
 391          wrong or that the call is simply not included in the trace.  */
 392
 393       /* Let's search for some actual call.  */
 394       caller = ftrace_find_call (gdbarch, prev->up);
 395       if (caller == NULL)
 396         {
 397           /* There is no call in PREV's back trace.  We assume that the
 398              branch trace did not include it.  */
 399
 400           /* Let's find the topmost call function - this skips tail calls.  */
 401           while (prev->up != NULL)
 402             prev = prev->up;
 403
 404           /* We maintain levels for a series of returns for which we have
 405              not seen the calls.
 406              We start at the preceding function's level in case this has
 407              already been a return for which we have not seen the call.
 408              We start at level 0 otherwise, to handle tail calls correctly.  */
 409           bfun->level = min (0, prev->level) - 1;
 410
 411           /* Fix up the call stack for PREV.  */
 412           ftrace_fixup_caller (prev, bfun, BFUN_UP_LINKS_TO_RET);
 413
 414           ftrace_debug (bfun, "new return - no caller");
 415         }
 416       else
 417         {
 418           /* There is a call in PREV's back trace to which we should have
 419              returned.  Let's remain at this level.  */
 420           bfun->level = prev->level;
 421
 422           ftrace_debug (bfun, "new return - unknown caller");
 423         }
 424     }
 425
 426   return bfun;
 427 }
 428
 429 /* Add a new function segment for a function switch.
 430    PREV is the chronologically preceding function segment.
 431    MFUN and FUN are the symbol information we have for this function.  */
 432
 433 static struct btrace_function *
 434 ftrace_new_switch (struct btrace_function *prev,
 435                    struct minimal_symbol *mfun,
 436                    struct symbol *fun)
 437 {
 438   struct btrace_function *bfun;
 439
 440   /* This is an unexplained function switch.  The call stack will likely
 441      be wrong at this point.  */
 442   bfun = ftrace_new_function (prev, mfun, fun);
 443
 444   /* We keep the function level.  */
 445   bfun->level = prev->level;
 446
 447   ftrace_debug (bfun, "new switch");
 448
 449   return bfun;
 450 }
 451
 452 /* Update BFUN with respect to the instruction at PC.  This may create new
 453    function segments.
 454    Return the chronologically latest function segment, never NULL.  */
 455
 456 static struct btrace_function *
 457 ftrace_update_function (struct gdbarch *gdbarch,
 458                         struct btrace_function *bfun, CORE_ADDR pc)
 459 {
 460   struct bound_minimal_symbol bmfun;
 461   struct minimal_symbol *mfun;
 462   struct symbol *fun;
 463   struct btrace_insn *last;
 464
 465   /* Try to determine the function we're in.  We use both types of symbols
 466      to avoid surprises when we sometimes get a full symbol and sometimes
 467      only a minimal symbol.  */
 468   fun = find_pc_function (pc);
 469   bmfun = lookup_minimal_symbol_by_pc (pc);
 470   mfun = bmfun.minsym;
 471
 472   if (fun == NULL && mfun == NULL)
 473     DEBUG_FTRACE ("no symbol at %s", core_addr_to_string_nz (pc));
 474
 475   /* If we didn't have a function before, we create one.  */
 476   if (bfun == NULL)
 477     return ftrace_new_function (bfun, mfun, fun);
 478
 479   /* Check the last instruction, if we have one.
 480      We do this check first, since it allows us to fill in the call stack
 481      links in addition to the normal flow links.  */
 482   last = NULL;
 483   if (!VEC_empty (btrace_insn_s, bfun->insn))
 484     last = VEC_last (btrace_insn_s, bfun->insn);
 485
 486   if (last != NULL)
 487     {
 488       CORE_ADDR lpc;
 489
 490       lpc = last->pc;
 491
 492       /* Check for returns.  */
 493       if (gdbarch_insn_is_ret (gdbarch, lpc))
 494         return ftrace_new_return (gdbarch, bfun, mfun, fun);
 495
 496       /* Check for calls.  */
 497       if (gdbarch_insn_is_call (gdbarch, lpc))
 498         {
 499           int size;
 500
 501           size = gdb_insn_length (gdbarch, lpc);
 502
 503           /* Ignore calls to the next instruction.  They are used for PIC.  */
 504           if (lpc + size != pc)
 505             return ftrace_new_call (bfun, mfun, fun);
 506         }
 507     }
 508
 509   /* Check if we're switching functions for some other reason.  */
 510   if (ftrace_function_switched (bfun, mfun, fun))
 511     {
 512       DEBUG_FTRACE ("switching from %s in %s at %s",
 513                     ftrace_print_insn_addr (last),
 514                     ftrace_print_function_name (bfun),
 515                     ftrace_print_filename (bfun));
 516
 517       if (last != NULL)
 518         {
 519           CORE_ADDR start, lpc;
 520
 521           start = get_pc_function_start (pc);
 522
 523           /* If we can't determine the function for PC, we treat a jump at
 524              the end of the block as tail call.  */
 525           if (start == 0)
 526             start = pc;
 527
 528           lpc = last->pc;
 529
 530           /* Jumps indicate optimized tail calls.  */
 531           if (start == pc && gdbarch_insn_is_jump (gdbarch, lpc))
 532             return ftrace_new_tailcall (bfun, mfun, fun);
 533         }
 534
 535       return ftrace_new_switch (bfun, mfun, fun);
 536     }
 537
 538   return bfun;
 539 }
 540
 541 /* Update BFUN's source range with respect to the instruction at PC.  */
 542
 543 static void
 544 ftrace_update_lines (struct btrace_function *bfun, CORE_ADDR pc)
 545 {
 546   struct symtab_and_line sal;
 547   const char *fullname;
 548
 549   sal = find_pc_line (pc, 0);
 550   if (sal.symtab == NULL || sal.line == 0)
 551     {
 552       DEBUG_FTRACE ("no lines at %s", core_addr_to_string_nz (pc));
 553       return;
 554     }
 555
 556   /* Check if we switched files.  This could happen if, say, a macro that
 557      is defined in another file is expanded here.  */
 558   fullname = symtab_to_fullname (sal.symtab);
 559   if (ftrace_skip_file (bfun, fullname))
 560     {
 561       DEBUG_FTRACE ("ignoring file at %s, file=%s",
 562                     core_addr_to_string_nz (pc), fullname);
 563       return;
 564     }
 565
 566   /* Update the line range.  */
 567   bfun->lbegin = min (bfun->lbegin, sal.line);
 568   bfun->lend = max (bfun->lend, sal.line);
 569
 570   if (record_debug > 1)
 571     ftrace_debug (bfun, "update lines");
 572 }
 573
 574 /* Add the instruction at PC to BFUN's instructions.  */
 575
 576 static void
 577 ftrace_update_insns (struct btrace_function *bfun, CORE_ADDR pc)
 578 {
 579   struct btrace_insn *insn;
 580
 581   insn = VEC_safe_push (btrace_insn_s, bfun->insn, NULL);
 582   insn->pc = pc;
 583
 584   if (record_debug > 1)
 585     ftrace_debug (bfun, "update insn");
 586 }
 587
 588 /* Compute the function branch trace from a block branch trace BTRACE for
 589    a thread given by BTINFO.  */
 590
 591 static void
 592 btrace_compute_ftrace (struct btrace_thread_info *btinfo,
 593                        VEC (btrace_block_s) *btrace)
 594 {
 595   struct btrace_function *begin, *end;
 596   struct gdbarch *gdbarch;
 597   unsigned int blk;
 598   int level;
 599
 600   DEBUG ("compute ftrace");
 601
 602   gdbarch = target_gdbarch ();
 603   begin = btinfo->begin;
 604   end = btinfo->end;
 605   level = begin != NULL ? -btinfo->level : INT_MAX;
 606   blk = VEC_length (btrace_block_s, btrace);
 607
 608   while (blk != 0)
 609     {
 610       btrace_block_s *block;
 611       CORE_ADDR pc;
 612
 613       blk -= 1;
 614
 615       block = VEC_index (btrace_block_s, btrace, blk);
 616       pc = block->begin;
 617
 618       for (;;)
 619         {
 620           int size;
 621
 622           /* We should hit the end of the block.  Warn if we went too far.  */
 623           if (block->end < pc)
 624             {
 625               warning (_("Recorded trace may be corrupted around %s."),
 626                        core_addr_to_string_nz (pc));
 627               break;
 628             }
 629
 630           end = ftrace_update_function (gdbarch, end, pc);
 631           if (begin == NULL)
 632             begin = end;
 633
 634           /* Maintain the function level offset.
 635              For all but the last block, we do it here.  */
 636           if (blk != 0)
 637             level = min (level, end->level);
 638
 639           ftrace_update_insns (end, pc);
 640           ftrace_update_lines (end, pc);
 641
 642           /* We're done once we pushed the instruction at the end.  */
 643           if (block->end == pc)
 644             break;
 645
 646           size = gdb_insn_length (gdbarch, pc);
 647
 648           /* Make sure we terminate if we fail to compute the size.  */
 649           if (size <= 0)
 650             {
 651               warning (_("Recorded trace may be incomplete around %s."),
 652                        core_addr_to_string_nz (pc));
 653               break;
 654             }
 655
 656           pc += size;
 657
 658           /* Maintain the function level offset.
 659              For the last block, we do it here to not consider the last
 660              instruction.
 661              Since the last instruction corresponds to the current instruction
 662              and is not really part of the execution history, it shouldn't
 663              affect the level.  */
 664           if (blk == 0)
 665             level = min (level, end->level);
 666         }
 667     }
 668
 669   btinfo->begin = begin;
 670   btinfo->end = end;
 671
 672   /* LEVEL is the minimal function level of all btrace function segments.
 673      Define the global level offset to -LEVEL so all function levels are
 674      normalized to start at zero.  */
 675   btinfo->level = -level;
 676 }
 677
 678 /* Add an entry for the current PC.  */
 679
 680 static void
 681 btrace_add_pc (struct thread_info *tp)
 682 {
 683   VEC (btrace_block_s) *btrace;
 684   struct btrace_block *block;
 685   struct regcache *regcache;
 686   struct cleanup *cleanup;
 687   CORE_ADDR pc;
 688
 689   regcache = get_thread_regcache (tp->ptid);
 690   pc = regcache_read_pc (regcache);
 691
 692   btrace = NULL;
 693   cleanup = make_cleanup (VEC_cleanup (btrace_block_s), &btrace);
 694
 695   block = VEC_safe_push (btrace_block_s, btrace, NULL);
 696   block->begin = pc;
 697   block->end = pc;
 698
 699   btrace_compute_ftrace (&tp->btrace, btrace);
 700
 701   do_cleanups (cleanup);
 702 }
 703
 704 /* See btrace.h.  */
 705
 706 void
 707 btrace_enable (struct thread_info *tp)
 708 {
 709   if (tp->btrace.target != NULL)
 710     return;
 711
 712   if (!target_supports_btrace ())
 713     error (_("Target does not support branch tracing."));
 714
 715   DEBUG ("enable thread %d (%s)", tp->num, target_pid_to_str (tp->ptid));
 716
 717   tp->btrace.target = target_enable_btrace (tp->ptid);
 718
 719   /* Add an entry for the current PC so we start tracing from where we
 720      enabled it.  */
 721   if (tp->btrace.target != NULL)
 722     btrace_add_pc (tp);
 723 }
 724
 725 /* See btrace.h.  */
 726
 727 void
 728 btrace_disable (struct thread_info *tp)
 729 {
 730   struct btrace_thread_info *btp = &tp->btrace;
 731   int errcode = 0;
 732
 733   if (btp->target == NULL)
 734     return;
 735
 736   DEBUG ("disable thread %d (%s)", tp->num, target_pid_to_str (tp->ptid));
 737
 738   target_disable_btrace (btp->target);
 739   btp->target = NULL;
 740
 741   btrace_clear (tp);
 742 }
 743
 744 /* See btrace.h.  */
 745
 746 void
 747 btrace_teardown (struct thread_info *tp)
 748 {
 749   struct btrace_thread_info *btp = &tp->btrace;
 750   int errcode = 0;
 751
 752   if (btp->target == NULL)
 753     return;
 754
 755   DEBUG ("teardown thread %d (%s)", tp->num, target_pid_to_str (tp->ptid));
 756
 757   target_teardown_btrace (btp->target);
 758   btp->target = NULL;
 759
 760   btrace_clear (tp);
 761 }
 762
 763 /* Adjust the block trace in order to stitch old and new trace together.
 764    BTRACE is the new delta trace between the last and the current stop.
 765    BTINFO is the old branch trace until the last stop.
 766    May modify BTRACE as well as the existing trace in BTINFO.
 767    Return 0 on success, -1 otherwise.  */
 768
 769 static int
 770 btrace_stitch_trace (VEC (btrace_block_s) **btrace,
 771                      const struct btrace_thread_info *btinfo)
 772 {
 773   struct btrace_function *last_bfun;
 774   struct btrace_insn *last_insn;
 775   btrace_block_s *first_new_block;
 776
 777   /* If we don't have trace, there's nothing to do.  */
 778   if (VEC_empty (btrace_block_s, *btrace))
 779     return 0;
 780
 781   last_bfun = btinfo->end;
 782   gdb_assert (last_bfun != NULL);
 783
 784   /* Beware that block trace starts with the most recent block, so the
 785      chronologically first block in the new trace is the last block in
 786      the new trace's block vector.  */
 787   first_new_block = VEC_last (btrace_block_s, *btrace);
 788   last_insn = VEC_last (btrace_insn_s, last_bfun->insn);
 789
 790   /* If the current PC at the end of the block is the same as in our current
 791      trace, there are two explanations:
 792        1. we executed the instruction and some branch brought us back.
 793        2. we have not made any progress.
 794      In the first case, the delta trace vector should contain at least two
 795      entries.
 796      In the second case, the delta trace vector should contain exactly one
 797      entry for the partial block containing the current PC.  Remove it.  */
 798   if (first_new_block->end == last_insn->pc
 799       && VEC_length (btrace_block_s, *btrace) == 1)
 800     {
 801       VEC_pop (btrace_block_s, *btrace);
 802       return 0;
 803     }
 804
 805   DEBUG ("stitching %s to %s", ftrace_print_insn_addr (last_insn),
 806          core_addr_to_string_nz (first_new_block->end));
 807
 808   /* Do a simple sanity check to make sure we don't accidentally end up
 809      with a bad block.  This should not occur in practice.  */
 810   if (first_new_block->end < last_insn->pc)
 811     {
 812       warning (_("Error while trying to read delta trace.  Falling back to "
 813                  "a full read."));
 814       return -1;
 815     }
 816
 817   /* We adjust the last block to start at the end of our current trace.  */
 818   gdb_assert (first_new_block->begin == 0);
 819   first_new_block->begin = last_insn->pc;
 820
 821   /* We simply pop the last insn so we can insert it again as part of
 822      the normal branch trace computation.
 823      Since instruction iterators are based on indices in the instructions
 824      vector, we don't leave any pointers dangling.  */
 825   DEBUG ("pruning insn at %s for stitching",
 826          ftrace_print_insn_addr (last_insn));
 827
 828   VEC_pop (btrace_insn_s, last_bfun->insn);
 829
 830   /* The instructions vector may become empty temporarily if this has
 831      been the only instruction in this function segment.
 832      This violates the invariant but will be remedied shortly by
 833      btrace_compute_ftrace when we add the new trace.  */
 834   return 0;
 835 }
 836
 837 /* Clear the branch trace histories in BTINFO.  */
 838
 839 static void
 840 btrace_clear_history (struct btrace_thread_info *btinfo)
 841 {
 842   xfree (btinfo->insn_history);
 843   xfree (btinfo->call_history);
 844   xfree (btinfo->replay);
 845
 846   btinfo->insn_history = NULL;
 847   btinfo->call_history = NULL;
 848   btinfo->replay = NULL;
 849 }
 850
 851 /* See btrace.h.  */
 852
 853 void
 854 btrace_fetch (struct thread_info *tp)
 855 {
 856   struct btrace_thread_info *btinfo;
 857   struct btrace_target_info *tinfo;
 858   VEC (btrace_block_s) *btrace;
 859   struct cleanup *cleanup;
 860   int errcode;
 861
 862   DEBUG ("fetch thread %d (%s)", tp->num, target_pid_to_str (tp->ptid));
 863
 864   btrace = NULL;
 865   btinfo = &tp->btrace;
 866   tinfo = btinfo->target;
 867   if (tinfo == NULL)
 868     return;
 869
 870   /* There's no way we could get new trace while replaying.
 871      On the other hand, delta trace would return a partial record with the
 872      current PC, which is the replay PC, not the last PC, as expected.  */
 873   if (btinfo->replay != NULL)
 874     return;
 875
 876   cleanup = make_cleanup (VEC_cleanup (btrace_block_s), &btrace);
 877
 878   /* Let's first try to extend the trace we already have.  */
 879   if (btinfo->end != NULL)
 880     {
 881       errcode = target_read_btrace (&btrace, tinfo, BTRACE_READ_DELTA);
 882       if (errcode == 0)
 883         {
 884           /* Success.  Let's try to stitch the traces together.  */
 885           errcode = btrace_stitch_trace (&btrace, btinfo);
 886         }
 887       else
 888         {
 889           /* We failed to read delta trace.  Let's try to read new trace.  */
 890           errcode = target_read_btrace (&btrace, tinfo, BTRACE_READ_NEW);
 891
 892           /* If we got any new trace, discard what we have.  */
 893           if (errcode == 0 && !VEC_empty (btrace_block_s, btrace))
 894             btrace_clear (tp);
 895         }
 896
 897       /* If we were not able to read the trace, we start over.  */
 898       if (errcode != 0)
 899         {
 900           btrace_clear (tp);
 901           errcode = target_read_btrace (&btrace, tinfo, BTRACE_READ_ALL);
 902         }
 903     }
 904   else
 905     errcode = target_read_btrace (&btrace, tinfo, BTRACE_READ_ALL);
 906
 907   /* If we were not able to read the branch trace, signal an error.  */
 908   if (errcode != 0)
 909     error (_("Failed to read branch trace."));
 910
 911   /* Compute the trace, provided we have any.  */
 912   if (!VEC_empty (btrace_block_s, btrace))
 913     {
 914       btrace_clear_history (btinfo);
 915       btrace_compute_ftrace (btinfo, btrace);
 916     }
 917
 918   do_cleanups (cleanup);
 919 }
 920
 921 /* See btrace.h.  */
 922
 923 void
 924 btrace_clear (struct thread_info *tp)
 925 {
 926   struct btrace_thread_info *btinfo;
 927   struct btrace_function *it, *trash;
 928
 929   DEBUG ("clear thread %d (%s)", tp->num, target_pid_to_str (tp->ptid));
 930
 931   /* Make sure btrace frames that may hold a pointer into the branch
 932      trace data are destroyed.  */
 933   reinit_frame_cache ();
 934
 935   btinfo = &tp->btrace;
 936
 937   it = btinfo->begin;
 938   while (it != NULL)
 939     {
 940       trash = it;
 941       it = it->flow.next;
 942
 943       xfree (trash);
 944     }
 945
 946   btinfo->begin = NULL;
 947   btinfo->end = NULL;
 948
 949   btrace_clear_history (btinfo);
 950 }
 951
 952 /* See btrace.h.  */
 953
 954 void
 955 btrace_free_objfile (struct objfile *objfile)
 956 {
 957   struct thread_info *tp;
 958
 959   DEBUG ("free objfile");
 960
 961   ALL_THREADS (tp)
 962     btrace_clear (tp);
 963 }
 964
 965 #if defined (HAVE_LIBEXPAT)
 966
 967 /* Check the btrace document version.  */
 968
 969 static void
 970 check_xml_btrace_version (struct gdb_xml_parser *parser,
 971                           const struct gdb_xml_element *element,
 972                           void *user_data, VEC (gdb_xml_value_s) *attributes)
 973 {
 974   const char *version = xml_find_attribute (attributes, "version")->value;
 975
 976   if (strcmp (version, "1.0") != 0)
 977     gdb_xml_error (parser, _("Unsupported btrace version: \"%s\""), version);
 978 }
 979
 980 /* Parse a btrace "block" xml record.  */
 981
 982 static void
 983 parse_xml_btrace_block (struct gdb_xml_parser *parser,
 984                         const struct gdb_xml_element *element,
 985                         void *user_data, VEC (gdb_xml_value_s) *attributes)
 986 {
 987   VEC (btrace_block_s) **btrace;
 988   struct btrace_block *block;
 989   ULONGEST *begin, *end;
 990
 991   btrace = user_data;
 992   block = VEC_safe_push (btrace_block_s, *btrace, NULL);
 993
 994   begin = xml_find_attribute (attributes, "begin")->value;
 995   end = xml_find_attribute (attributes, "end")->value;
 996
 997   block->begin = *begin;
 998   block->end = *end;
 999 }
1000
1001 static const struct gdb_xml_attribute block_attributes[] = {
1002   { "begin", GDB_XML_AF_NONE, gdb_xml_parse_attr_ulongest, NULL },
1003   { "end", GDB_XML_AF_NONE, gdb_xml_parse_attr_ulongest, NULL },
1004   { NULL, GDB_XML_AF_NONE, NULL, NULL }
1005 };
1006
1007 static const struct gdb_xml_attribute btrace_attributes[] = {
1008   { "version", GDB_XML_AF_NONE, NULL, NULL },
1009   { NULL, GDB_XML_AF_NONE, NULL, NULL }
1010 };
1011
1012 static const struct gdb_xml_element btrace_children[] = {
1013   { "block", block_attributes, NULL,
1014     GDB_XML_EF_REPEATABLE | GDB_XML_EF_OPTIONAL, parse_xml_btrace_block, NULL },
1015   { NULL, NULL, NULL, GDB_XML_EF_NONE, NULL, NULL }
1016 };
1017
1018 static const struct gdb_xml_element btrace_elements[] = {
1019   { "btrace", btrace_attributes, btrace_children, GDB_XML_EF_NONE,
1020     check_xml_btrace_version, NULL },
1021   { NULL, NULL, NULL, GDB_XML_EF_NONE, NULL, NULL }
1022 };
1023
1024 #endif /* defined (HAVE_LIBEXPAT) */
1025
1026 /* See btrace.h.  */
1027
1028 VEC (btrace_block_s) *
1029 parse_xml_btrace (const char *buffer)
1030 {
1031   VEC (btrace_block_s) *btrace = NULL;
1032   struct cleanup *cleanup;
1033   int errcode;
1034
1035 #if defined (HAVE_LIBEXPAT)
1036
1037   cleanup = make_cleanup (VEC_cleanup (btrace_block_s), &btrace);
1038   errcode = gdb_xml_parse_quick (_("btrace"), "btrace.dtd", btrace_elements,
1039                                  buffer, &btrace);
1040   if (errcode != 0)
1041     error (_("Error parsing branch trace."));
1042
1043   /* Keep parse results.  */
1044   discard_cleanups (cleanup);
1045
1046 #else  /* !defined (HAVE_LIBEXPAT) */
1047
1048   error (_("Cannot process branch trace.  XML parsing is not supported."));
1049
1050 #endif  /* !defined (HAVE_LIBEXPAT) */
1051
1052   return btrace;
1053 }
1054
1055 /* See btrace.h.  */
1056
1057 const struct btrace_insn *
1058 btrace_insn_get (const struct btrace_insn_iterator *it)
1059 {
1060   const struct btrace_function *bfun;
1061   unsigned int index, end;
1062
1063   index = it->index;
1064   bfun = it->function;
1065
1066   /* The index is within the bounds of this function's instruction vector.  */
1067   end = VEC_length (btrace_insn_s, bfun->insn);
1068   gdb_assert (0 < end);
1069   gdb_assert (index < end);
1070
1071   return VEC_index (btrace_insn_s, bfun->insn, index);
1072 }
1073
1074 /* See btrace.h.  */
1075
1076 unsigned int
1077 btrace_insn_number (const struct btrace_insn_iterator *it)
1078 {
1079   const struct btrace_function *bfun;
1080
1081   bfun = it->function;
1082   return bfun->insn_offset + it->index;
1083 }
1084
1085 /* See btrace.h.  */
1086
1087 void
1088 btrace_insn_begin (struct btrace_insn_iterator *it,
1089                    const struct btrace_thread_info *btinfo)
1090 {
1091   const struct btrace_function *bfun;
1092
1093   bfun = btinfo->begin;
1094   if (bfun == NULL)
1095     error (_("No trace."));
1096
1097   it->function = bfun;
1098   it->index = 0;
1099 }
1100
1101 /* See btrace.h.  */
1102
1103 void
1104 btrace_insn_end (struct btrace_insn_iterator *it,
1105                  const struct btrace_thread_info *btinfo)
1106 {
1107   const struct btrace_function *bfun;
1108   unsigned int length;
1109
1110   bfun = btinfo->end;
1111   if (bfun == NULL)
1112     error (_("No trace."));
1113
1114   /* The last instruction in the last function is the current instruction.
1115      We point to it - it is one past the end of the execution trace.  */
1116   length = VEC_length (btrace_insn_s, bfun->insn);
1117
1118   it->function = bfun;
1119   it->index = length - 1;
1120 }
1121
1122 /* See btrace.h.  */
1123
1124 unsigned int
1125 btrace_insn_next (struct btrace_insn_iterator *it, unsigned int stride)
1126 {
1127   const struct btrace_function *bfun;
1128   unsigned int index, steps;
1129
1130   bfun = it->function;
1131   steps = 0;
1132   index = it->index;
1133
1134   while (stride != 0)
1135     {
1136       unsigned int end, space, adv;
1137
1138       end = VEC_length (btrace_insn_s, bfun->insn);
1139
1140       gdb_assert (0 < end);
1141       gdb_assert (index < end);
1142
1143       /* Compute the number of instructions remaining in this segment.  */
1144       space = end - index;
1145
1146       /* Advance the iterator as far as possible within this segment.  */
1147       adv = min (space, stride);
1148       stride -= adv;
1149       index += adv;
1150       steps += adv;
1151
1152       /* Move to the next function if we're at the end of this one.  */
1153       if (index == end)
1154         {
1155           const struct btrace_function *next;
1156
1157           next = bfun->flow.next;
1158           if (next == NULL)
1159             {
1160               /* We stepped past the last function.
1161
1162                  Let's adjust the index to point to the last instruction in
1163                  the previous function.  */
1164               index -= 1;
1165               steps -= 1;
1166               break;
1167             }
1168
1169           /* We now point to the first instruction in the new function.  */
1170           bfun = next;
1171           index = 0;
1172         }
1173
1174       /* We did make progress.  */
1175       gdb_assert (adv > 0);
1176     }
1177
1178   /* Update the iterator.  */
1179   it->function = bfun;
1180   it->index = index;
1181
1182   return steps;
1183 }
1184
1185 /* See btrace.h.  */
1186
1187 unsigned int
1188 btrace_insn_prev (struct btrace_insn_iterator *it, unsigned int stride)
1189 {
1190   const struct btrace_function *bfun;
1191   unsigned int index, steps;
1192
1193   bfun = it->function;
1194   steps = 0;
1195   index = it->index;
1196
1197   while (stride != 0)
1198     {
1199       unsigned int adv;
1200
1201       /* Move to the previous function if we're at the start of this one.  */
1202       if (index == 0)
1203         {
1204           const struct btrace_function *prev;
1205
1206           prev = bfun->flow.prev;
1207           if (prev == NULL)
1208             break;
1209
1210           /* We point to one after the last instruction in the new function.  */
1211           bfun = prev;
1212           index = VEC_length (btrace_insn_s, bfun->insn);
1213
1214           /* There is at least one instruction in this function segment.  */
1215           gdb_assert (index > 0);
1216         }
1217
1218       /* Advance the iterator as far as possible within this segment.  */
1219       adv = min (index, stride);
1220       stride -= adv;
1221       index -= adv;
1222       steps += adv;
1223
1224       /* We did make progress.  */
1225       gdb_assert (adv > 0);
1226     }
1227
1228   /* Update the iterator.  */
1229   it->function = bfun;
1230   it->index = index;
1231
1232   return steps;
1233 }
1234
1235 /* See btrace.h.  */
1236
1237 int
1238 btrace_insn_cmp (const struct btrace_insn_iterator *lhs,
1239                  const struct btrace_insn_iterator *rhs)
1240 {
1241   unsigned int lnum, rnum;
1242
1243   lnum = btrace_insn_number (lhs);
1244   rnum = btrace_insn_number (rhs);
1245
1246   return (int) (lnum - rnum);
1247 }
1248
1249 /* See btrace.h.  */
1250
1251 int
1252 btrace_find_insn_by_number (struct btrace_insn_iterator *it,
1253                             const struct btrace_thread_info *btinfo,
1254                             unsigned int number)
1255 {
1256   const struct btrace_function *bfun;
1257   unsigned int end;
1258
1259   for (bfun = btinfo->end; bfun != NULL; bfun = bfun->flow.prev)
1260     if (bfun->insn_offset <= number)
1261       break;
1262
1263   if (bfun == NULL)
1264     return 0;
1265
1266   end = bfun->insn_offset + VEC_length (btrace_insn_s, bfun->insn);
1267   if (end <= number)
1268     return 0;
1269
1270   it->function = bfun;
1271   it->index = number - bfun->insn_offset;
1272
1273   return 1;
1274 }
1275
1276 /* See btrace.h.  */
1277
1278 const struct btrace_function *
1279 btrace_call_get (const struct btrace_call_iterator *it)
1280 {
1281   return it->function;
1282 }
1283
1284 /* See btrace.h.  */
1285
1286 unsigned int
1287 btrace_call_number (const struct btrace_call_iterator *it)
1288 {
1289   const struct btrace_thread_info *btinfo;
1290   const struct btrace_function *bfun;
1291   unsigned int insns;
1292
1293   btinfo = it->btinfo;
1294   bfun = it->function;
1295   if (bfun != NULL)
1296     return bfun->number;
1297
1298   /* For the end iterator, i.e. bfun == NULL, we return one more than the
1299      number of the last function.  */
1300   bfun = btinfo->end;
1301   insns = VEC_length (btrace_insn_s, bfun->insn);
1302
1303   /* If the function contains only a single instruction (i.e. the current
1304      instruction), it will be skipped and its number is already the number
1305      we seek.  */
1306   if (insns == 1)
1307     return bfun->number;
1308
1309   /* Otherwise, return one more than the number of the last function.  */
1310   return bfun->number + 1;
1311 }
1312
1313 /* See btrace.h.  */
1314
1315 void
1316 btrace_call_begin (struct btrace_call_iterator *it,
1317                    const struct btrace_thread_info *btinfo)
1318 {
1319   const struct btrace_function *bfun;
1320
1321   bfun = btinfo->begin;
1322   if (bfun == NULL)
1323     error (_("No trace."));
1324
1325   it->btinfo = btinfo;
1326   it->function = bfun;
1327 }
1328
1329 /* See btrace.h.  */
1330
1331 void
1332 btrace_call_end (struct btrace_call_iterator *it,
1333                  const struct btrace_thread_info *btinfo)
1334 {
1335   const struct btrace_function *bfun;
1336
1337   bfun = btinfo->end;
1338   if (bfun == NULL)
1339     error (_("No trace."));
1340
1341   it->btinfo = btinfo;
1342   it->function = NULL;
1343 }
1344
1345 /* See btrace.h.  */
1346
1347 unsigned int
1348 btrace_call_next (struct btrace_call_iterator *it, unsigned int stride)
1349 {
1350   const struct btrace_function *bfun;
1351   unsigned int steps;
1352
1353   bfun = it->function;
1354   steps = 0;
1355   while (bfun != NULL)
1356     {
1357       const struct btrace_function *next;
1358       unsigned int insns;
1359
1360       next = bfun->flow.next;
1361       if (next == NULL)
1362         {
1363           /* Ignore the last function if it only contains a single
1364              (i.e. the current) instruction.  */
1365           insns = VEC_length (btrace_insn_s, bfun->insn);
1366           if (insns == 1)
1367             steps -= 1;
1368         }
1369
1370       if (stride == steps)
1371         break;
1372
1373       bfun = next;
1374       steps += 1;
1375     }
1376
1377   it->function = bfun;
1378   return steps;
1379 }
1380
1381 /* See btrace.h.  */
1382
1383 unsigned int
1384 btrace_call_prev (struct btrace_call_iterator *it, unsigned int stride)
1385 {
1386   const struct btrace_thread_info *btinfo;
1387   const struct btrace_function *bfun;
1388   unsigned int steps;
1389
1390   bfun = it->function;
1391   steps = 0;
1392
1393   if (bfun == NULL)
1394     {
1395       unsigned int insns;
1396
1397       btinfo = it->btinfo;
1398       bfun = btinfo->end;
1399       if (bfun == NULL)
1400         return 0;
1401
1402       /* Ignore the last function if it only contains a single
1403          (i.e. the current) instruction.  */
1404       insns = VEC_length (btrace_insn_s, bfun->insn);
1405       if (insns == 1)
1406         bfun = bfun->flow.prev;
1407
1408       if (bfun == NULL)
1409         return 0;
1410
1411       steps += 1;
1412     }
1413
1414   while (steps < stride)
1415     {
1416       const struct btrace_function *prev;
1417
1418       prev = bfun->flow.prev;
1419       if (prev == NULL)
1420         break;
1421
1422       bfun = prev;
1423       steps += 1;
1424     }
1425
1426   it->function = bfun;
1427   return steps;
1428 }
1429
1430 /* See btrace.h.  */
1431
1432 int
1433 btrace_call_cmp (const struct btrace_call_iterator *lhs,
1434                  const struct btrace_call_iterator *rhs)
1435 {
1436   unsigned int lnum, rnum;
1437
1438   lnum = btrace_call_number (lhs);
1439   rnum = btrace_call_number (rhs);
1440
1441   return (int) (lnum - rnum);
1442 }
1443
1444 /* See btrace.h.  */
1445
1446 int
1447 btrace_find_call_by_number (struct btrace_call_iterator *it,
1448                             const struct btrace_thread_info *btinfo,
1449                             unsigned int number)
1450 {
1451   const struct btrace_function *bfun;
1452
1453   for (bfun = btinfo->end; bfun != NULL; bfun = bfun->flow.prev)
1454     {
1455       unsigned int bnum;
1456
1457       bnum = bfun->number;
1458       if (number == bnum)
1459         {
1460           it->btinfo = btinfo;
1461           it->function = bfun;
1462           return 1;
1463         }
1464
1465       /* Functions are ordered and numbered consecutively.  We could bail out
1466          earlier.  On the other hand, it is very unlikely that we search for
1467          a nonexistent function.  */
1468   }
1469
1470   return 0;
1471 }
1472
1473 /* See btrace.h.  */
1474
1475 void
1476 btrace_set_insn_history (struct btrace_thread_info *btinfo,
1477                          const struct btrace_insn_iterator *begin,
1478                          const struct btrace_insn_iterator *end)
1479 {
1480   if (btinfo->insn_history == NULL)
1481     btinfo->insn_history = xzalloc (sizeof (*btinfo->insn_history));
1482
1483   btinfo->insn_history->begin = *begin;
1484   btinfo->insn_history->end = *end;
1485 }
1486
1487 /* See btrace.h.  */
1488
1489 void
1490 btrace_set_call_history (struct btrace_thread_info *btinfo,
1491                          const struct btrace_call_iterator *begin,
1492                          const struct btrace_call_iterator *end)
1493 {
1494   gdb_assert (begin->btinfo == end->btinfo);
1495
1496   if (btinfo->call_history == NULL)
1497     btinfo->call_history = xzalloc (sizeof (*btinfo->call_history));
1498
1499   btinfo->call_history->begin = *begin;
1500   btinfo->call_history->end = *end;
1501 }
1502
1503 /* See btrace.h.  */
1504
1505 int
1506 btrace_is_replaying (struct thread_info *tp)
1507 {
1508   return tp->btrace.replay != NULL;
1509 }
1510
1511 /* See btrace.h.  */
1512
1513 int
1514 btrace_is_empty (struct thread_info *tp)
1515 {
1516   struct btrace_insn_iterator begin, end;
1517   struct btrace_thread_info *btinfo;
1518
1519   btinfo = &tp->btrace;
1520
1521   if (btinfo->begin == NULL)
1522     return 1;
1523
1524   btrace_insn_begin (&begin, btinfo);
1525   btrace_insn_end (&end, btinfo);
1526
1527   return btrace_insn_cmp (&begin, &end) == 0;
1528 }