bfd/dwarf1.c

   1 /* DWARF 1 find nearest line (_bfd_dwarf1_find_nearest_line).
   2    Copyright (C) 1998-2023 Free Software Foundation, Inc.
   3
   4    Written by Gavin Romig-Koch of Cygnus Solutions (gavin@cygnus.com).
   5
   6    This file is part of BFD.
   7
   8    This program is free software; you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation; either version 3 of the License, or (at
  11    your option) any later version.
  12
  13    This program is distributed in the hope that it will be useful, but
  14    WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16    General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program; if not, write to the Free Software
  20    Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
  21    MA 02110-1301, USA.  */
  22
  23 #include "sysdep.h"
  24 #include "bfd.h"
  25 #include "libiberty.h"
  26 #include "libbfd.h"
  27 #include "elf-bfd.h"
  28 #include "elf/dwarf.h"
  29
  30 /* dwarf1_debug is the starting point for all dwarf1 info.  */
  31
  32 struct dwarf1_debug
  33 {
  34   /* The bfd we are working with.  */
  35   bfd* abfd;
  36
  37   /* Pointer to the symbol table.  */
  38   asymbol** syms;
  39
  40   /* List of already parsed compilation units.  */
  41   struct dwarf1_unit* lastUnit;
  42
  43   /* The buffer for the .debug section.
  44      Zero indicates that the .debug section failed to load.  */
  45   bfd_byte *debug_section;
  46
  47   /* Pointer to the end of the .debug_info section memory buffer.  */
  48   bfd_byte *debug_section_end;
  49
  50   /* The buffer for the .line section.  */
  51   bfd_byte *line_section;
  52
  53   /* End of that buffer.  */
  54   bfd_byte *line_section_end;
  55
  56   /* The current or next unread die within the .debug section.  */
  57   bfd_byte *currentDie;
  58 };
  59
  60 /* One dwarf1_unit for each parsed compilation unit die.  */
  61
  62 struct dwarf1_unit
  63 {
  64   /* Linked starting from stash->lastUnit.  */
  65   struct dwarf1_unit* prev;
  66
  67   /* Name of the compilation unit.  */
  68   char *name;
  69
  70   /* The highest and lowest address used in the compilation unit.  */
  71   unsigned long low_pc;
  72   unsigned long high_pc;
  73
  74   /* Does this unit have a statement list?  */
  75   int has_stmt_list;
  76
  77   /* If any, the offset of the line number table in the .line section.  */
  78   unsigned long stmt_list_offset;
  79
  80   /* If non-zero, a pointer to the first child of this unit.  */
  81   bfd_byte *first_child;
  82
  83   /* How many line entries?  */
  84   unsigned long line_count;
  85
  86   /* The decoded line number table (line_count entries).  */
  87   struct linenumber* linenumber_table;
  88
  89   /* The list of functions in this unit.  */
  90   struct dwarf1_func* func_list;
  91 };
  92
  93 /* One dwarf1_func for each parsed function die.  */
  94
  95 struct dwarf1_func
  96 {
  97   /* Linked starting from aUnit->func_list.  */
  98   struct dwarf1_func* prev;
  99
 100   /* Name of function.  */
 101   char* name;
 102
 103   /* The highest and lowest address used in the compilation unit.  */
 104   unsigned long low_pc;
 105   unsigned long high_pc;
 106 };
 107
 108 /* Used to return info about a parsed die.  */
 109 struct die_info
 110 {
 111   unsigned long length;
 112   unsigned long sibling;
 113   unsigned long low_pc;
 114   unsigned long high_pc;
 115   unsigned long stmt_list_offset;
 116
 117   char* name;
 118
 119   int has_stmt_list;
 120
 121   unsigned short tag;
 122 };
 123
 124 /* Parsed line number information.  */
 125 struct linenumber
 126 {
 127   /* First address in the line.  */
 128   unsigned long addr;
 129
 130   /* The line number.  */
 131   unsigned long linenumber;
 132 };
 133
 134 /* Find the form of an attr, from the attr field.  */
 135 #define FORM_FROM_ATTR(attr)    ((attr) & 0xF)  /* Implicitly specified.  */
 136
 137 /* Return a newly allocated dwarf1_unit.  It should be cleared and
 138    then attached into the 'stash' at 'stash->lastUnit'.  */
 139
 140 static struct dwarf1_unit*
 141 alloc_dwarf1_unit (struct dwarf1_debug* stash)
 142 {
 143   size_t amt = sizeof (struct dwarf1_unit);
 144
 145   struct dwarf1_unit* x = (struct dwarf1_unit *) bfd_zalloc (stash->abfd, amt);
 146   if (x)
 147     {
 148       x->prev = stash->lastUnit;
 149       stash->lastUnit = x;
 150     }
 151
 152   return x;
 153 }
 154
 155 /* Return a newly allocated dwarf1_func.  It must be cleared and
 156    attached into 'aUnit' at 'aUnit->func_list'.  */
 157
 158 static struct dwarf1_func *
 159 alloc_dwarf1_func (struct dwarf1_debug* stash, struct dwarf1_unit* aUnit)
 160 {
 161   size_t amt = sizeof (struct dwarf1_func);
 162
 163   struct dwarf1_func* x = (struct dwarf1_func *) bfd_zalloc (stash->abfd, amt);
 164   if (x)
 165     {
 166       x->prev = aUnit->func_list;
 167       aUnit->func_list = x;
 168     }
 169
 170   return x;
 171 }
 172
 173 /* parse_die - parse a Dwarf1 die.
 174    Parse the die starting at 'aDiePtr' into 'aDieInfo'.
 175    'abfd' must be the bfd from which the section that 'aDiePtr'
 176    points to was pulled from.
 177
 178    Return FALSE if the die is invalidly formatted; TRUE otherwise.  */
 179
 180 static bool
 181 parse_die (bfd *             abfd,
 182            struct die_info * aDieInfo,
 183            bfd_byte *        aDiePtr,
 184            bfd_byte *        aDiePtrEnd)
 185 {
 186   bfd_byte *this_die = aDiePtr;
 187   bfd_byte *xptr = this_die;
 188
 189   memset (aDieInfo, 0, sizeof (* aDieInfo));
 190
 191   /* First comes the length.  */
 192   if (xptr + 4 > aDiePtrEnd)
 193     return false;
 194   aDieInfo->length = bfd_get_32 (abfd, xptr);
 195   xptr += 4;
 196   if (aDieInfo->length <= 4
 197       || (size_t) (aDiePtrEnd - this_die) < aDieInfo->length)
 198     return false;
 199   aDiePtrEnd = this_die + aDieInfo->length;
 200   if (aDieInfo->length < 6)
 201     {
 202       /* Just padding bytes.  */
 203       aDieInfo->tag = TAG_padding;
 204       return true;
 205     }
 206
 207   /* Then the tag.  */
 208   if (xptr + 2 > aDiePtrEnd)
 209     return false;
 210   aDieInfo->tag = bfd_get_16 (abfd, xptr);
 211   xptr += 2;
 212
 213   /* Then the attributes.  */
 214   while (xptr + 2 <= aDiePtrEnd)
 215     {
 216       unsigned int   block_len;
 217       unsigned short attr;
 218
 219       /* Parse the attribute based on its form.  This section
 220          must handle all dwarf1 forms, but need only handle the
 221          actual attributes that we care about.  */
 222       attr = bfd_get_16 (abfd, xptr);
 223       xptr += 2;
 224
 225       switch (FORM_FROM_ATTR (attr))
 226         {
 227         case FORM_DATA2:
 228           xptr += 2;
 229           break;
 230         case FORM_DATA4:
 231         case FORM_REF:
 232           if (xptr + 4 <= aDiePtrEnd)
 233             {
 234               if (attr == AT_sibling)
 235                 aDieInfo->sibling = bfd_get_32 (abfd, xptr);
 236               else if (attr == AT_stmt_list)
 237                 {
 238                   aDieInfo->stmt_list_offset = bfd_get_32 (abfd, xptr);
 239                   aDieInfo->has_stmt_list = 1;
 240                 }
 241             }
 242           xptr += 4;
 243           break;
 244         case FORM_DATA8:
 245           xptr += 8;
 246           break;
 247         case FORM_ADDR:
 248           if (xptr + 4 <= aDiePtrEnd)
 249             {
 250               if (attr == AT_low_pc)
 251                 aDieInfo->low_pc = bfd_get_32 (abfd, xptr);
 252               else if (attr == AT_high_pc)
 253                 aDieInfo->high_pc = bfd_get_32 (abfd, xptr);
 254             }
 255           xptr += 4;
 256           break;
 257         case FORM_BLOCK2:
 258           if (xptr + 2 <= aDiePtrEnd)
 259             {
 260               block_len = bfd_get_16 (abfd, xptr);
 261               if ((size_t) (aDiePtrEnd - xptr) < block_len)
 262                 return false;
 263               xptr += block_len;
 264             }
 265           xptr += 2;
 266           break;
 267         case FORM_BLOCK4:
 268           if (xptr + 4 <= aDiePtrEnd)
 269             {
 270               block_len = bfd_get_32 (abfd, xptr);
 271               if ((size_t) (aDiePtrEnd - xptr) < block_len)
 272                 return false;
 273               xptr += block_len;
 274             }
 275           xptr += 4;
 276           break;
 277         case FORM_STRING:
 278           if (attr == AT_name)
 279             aDieInfo->name = (char *) xptr;
 280           xptr += strnlen ((char *) xptr, aDiePtrEnd - xptr) + 1;
 281           break;
 282         }
 283     }
 284
 285   return true;
 286 }
 287
 288 /* Parse a dwarf1 line number table for 'aUnit->stmt_list_offset'
 289    into 'aUnit->linenumber_table'.  Return FALSE if an error
 290    occurs; TRUE otherwise.  */
 291
 292 static bool
 293 parse_line_table (struct dwarf1_debug* stash, struct dwarf1_unit* aUnit)
 294 {
 295   bfd_byte *xptr;
 296
 297   /* Load the ".line" section from the bfd if we haven't already.  */
 298   if (stash->line_section == 0)
 299     {
 300       asection *msec;
 301       bfd_size_type size;
 302
 303       msec = bfd_get_section_by_name (stash->abfd, ".line");
 304       if (! msec || (msec->flags & SEC_HAS_CONTENTS) == 0)
 305         return false;
 306
 307       size = msec->rawsize ? msec->rawsize : msec->size;
 308       stash->line_section
 309         = bfd_simple_get_relocated_section_contents (stash->abfd, msec, NULL,
 310                                                      stash->syms);
 311
 312       if (! stash->line_section)
 313         return false;
 314
 315       stash->line_section_end = stash->line_section + size;
 316     }
 317
 318   xptr = stash->line_section + aUnit->stmt_list_offset;
 319   if (xptr + 8 <= stash->line_section_end)
 320     {
 321       unsigned long eachLine;
 322       bfd_byte *tblend;
 323       unsigned long base;
 324       bfd_size_type amt;
 325
 326       /* First comes the length.  */
 327       tblend = bfd_get_32 (stash->abfd, (bfd_byte *) xptr) + xptr;
 328       xptr += 4;
 329
 330       /* Then the base address for each address in the table.  */
 331       base = bfd_get_32 (stash->abfd, (bfd_byte *) xptr);
 332       xptr += 4;
 333
 334       /* How many line entrys?
 335          10 = 4 (line number) + 2 (pos in line) + 4 (address in line).  */
 336       aUnit->line_count = (tblend - xptr) / 10;
 337
 338       /* Allocate an array for the entries.  */
 339       amt = sizeof (struct linenumber) * aUnit->line_count;
 340       aUnit->linenumber_table = (struct linenumber *) bfd_alloc (stash->abfd,
 341                                                                  amt);
 342       if (!aUnit->linenumber_table)
 343         return false;
 344
 345       for (eachLine = 0; eachLine < aUnit->line_count; eachLine++)
 346         {
 347           if (xptr + 10 > stash->line_section_end)
 348             {
 349               aUnit->line_count = eachLine;
 350               break;
 351             }
 352           /* A line number.  */
 353           aUnit->linenumber_table[eachLine].linenumber
 354             = bfd_get_32 (stash->abfd, (bfd_byte *) xptr);
 355           xptr += 4;
 356
 357           /* Skip the position within the line.  */
 358           xptr += 2;
 359
 360           /* And finally the address.  */
 361           aUnit->linenumber_table[eachLine].addr
 362             = base + bfd_get_32 (stash->abfd, (bfd_byte *) xptr);
 363           xptr += 4;
 364         }
 365     }
 366
 367   return true;
 368 }
 369
 370 /* Parse each function die in a compilation unit 'aUnit'.
 371    The first child die of 'aUnit' should be in 'aUnit->first_child',
 372    the result is placed in 'aUnit->func_list'.
 373    Return FALSE if error; TRUE otherwise.  */
 374
 375 static bool
 376 parse_functions_in_unit (struct dwarf1_debug* stash, struct dwarf1_unit* aUnit)
 377 {
 378   bfd_byte *eachDie;
 379
 380   if (aUnit->first_child)
 381     for (eachDie = aUnit->first_child;
 382          eachDie < stash->debug_section_end;
 383          )
 384       {
 385         struct die_info eachDieInfo;
 386
 387         if (! parse_die (stash->abfd, &eachDieInfo, eachDie,
 388                          stash->debug_section_end))
 389           return false;
 390
 391         if (eachDieInfo.tag == TAG_global_subroutine
 392             || eachDieInfo.tag == TAG_subroutine
 393             || eachDieInfo.tag == TAG_inlined_subroutine
 394             || eachDieInfo.tag == TAG_entry_point)
 395           {
 396             struct dwarf1_func* aFunc = alloc_dwarf1_func (stash,aUnit);
 397             if (!aFunc)
 398               return false;
 399
 400             aFunc->name = eachDieInfo.name;
 401             aFunc->low_pc = eachDieInfo.low_pc;
 402             aFunc->high_pc = eachDieInfo.high_pc;
 403           }
 404
 405         /* Move to next sibling, if none, end loop */
 406         if (eachDieInfo.sibling)
 407           eachDie = stash->debug_section + eachDieInfo.sibling;
 408         else
 409           break;
 410       }
 411
 412   return true;
 413 }
 414
 415 /* Find the nearest line to 'addr' in 'aUnit'.
 416    Return whether we found the line (or a function) without error.  */
 417
 418 static bool
 419 dwarf1_unit_find_nearest_line (struct dwarf1_debug* stash,
 420                                struct dwarf1_unit* aUnit,
 421                                unsigned long addr,
 422                                const char **filename_ptr,
 423                                const char **functionname_ptr,
 424                                unsigned int *linenumber_ptr)
 425 {
 426   int line_p = false;
 427   int func_p = false;
 428
 429   if (aUnit->low_pc <= addr && addr < aUnit->high_pc)
 430     {
 431       if (aUnit->has_stmt_list)
 432         {
 433           unsigned long i;
 434           struct dwarf1_func* eachFunc;
 435
 436           if (! aUnit->linenumber_table)
 437             {
 438               if (! parse_line_table (stash, aUnit))
 439                 return false;
 440             }
 441
 442           if (! aUnit->func_list)
 443             {
 444               if (! parse_functions_in_unit (stash, aUnit))
 445                 return false;
 446             }
 447
 448           for (i = 0; i < aUnit->line_count; i++)
 449             {
 450               if (aUnit->linenumber_table[i].addr <= addr
 451                   && addr < aUnit->linenumber_table[i+1].addr)
 452                 {
 453                   *filename_ptr = aUnit->name;
 454                   *linenumber_ptr = aUnit->linenumber_table[i].linenumber;
 455                   line_p = true;
 456                   break;
 457                 }
 458             }
 459
 460           for (eachFunc = aUnit->func_list;
 461                eachFunc;
 462                eachFunc = eachFunc->prev)
 463             {
 464               if (eachFunc->low_pc <= addr
 465                   && addr < eachFunc->high_pc)
 466                 {
 467                   *functionname_ptr = eachFunc->name;
 468                   func_p = true;
 469                   break;
 470                 }
 471             }
 472         }
 473     }
 474
 475   return line_p || func_p;
 476 }
 477
 478 /* The DWARF 1 version of find_nearest line.
 479    Return TRUE if the line is found without error.  */
 480
 481 bool
 482 _bfd_dwarf1_find_nearest_line (bfd *abfd,
 483                                asymbol **symbols,
 484                                asection *section,
 485                                bfd_vma offset,
 486                                const char **filename_ptr,
 487                                const char **functionname_ptr,
 488                                unsigned int *linenumber_ptr)
 489 {
 490   struct dwarf1_debug *stash = elf_tdata (abfd)->dwarf1_find_line_info;
 491
 492   struct dwarf1_unit* eachUnit;
 493
 494   /* What address are we looking for? */
 495   unsigned long addr = (unsigned long)(offset + section->vma);
 496
 497   *filename_ptr = NULL;
 498   *functionname_ptr = NULL;
 499   *linenumber_ptr = 0;
 500
 501   if (! stash)
 502     {
 503       asection *msec;
 504       bfd_size_type size = sizeof (struct dwarf1_debug);
 505
 506       stash = elf_tdata (abfd)->dwarf1_find_line_info
 507         = (struct dwarf1_debug *) bfd_zalloc (abfd, size);
 508
 509       if (! stash)
 510         return false;
 511
 512       msec = bfd_get_section_by_name (abfd, ".debug");
 513       if (! msec
 514           || (msec->flags & SEC_HAS_CONTENTS) == 0)
 515         /* No dwarf1 info.  Note that at this point the stash
 516            has been allocated, but contains zeros, this lets
 517            future calls to this function fail quicker.  */
 518         return false;
 519
 520       size = msec->rawsize ? msec->rawsize : msec->size;
 521       stash->debug_section
 522         = bfd_simple_get_relocated_section_contents (abfd, msec, NULL,
 523                                                      symbols);
 524
 525       if (! stash->debug_section)
 526         return false;
 527
 528       stash->debug_section_end = stash->debug_section + size;
 529       stash->currentDie = stash->debug_section;
 530       stash->abfd = abfd;
 531       stash->syms = symbols;
 532     }
 533
 534   /* A null debug_section indicates that there was no dwarf1 info
 535      or that an error occured while setting up the stash.  */
 536
 537   if (! stash->debug_section)
 538     return false;
 539
 540   /* Look at the previously parsed units to see if any contain
 541      the addr.  */
 542   for (eachUnit = stash->lastUnit; eachUnit; eachUnit = eachUnit->prev)
 543     if (eachUnit->low_pc <= addr && addr < eachUnit->high_pc)
 544       return dwarf1_unit_find_nearest_line (stash, eachUnit, addr,
 545                                             filename_ptr,
 546                                             functionname_ptr,
 547                                             linenumber_ptr);
 548
 549   while (stash->currentDie < stash->debug_section_end)
 550     {
 551       struct die_info aDieInfo;
 552
 553       if (! parse_die (stash->abfd, &aDieInfo, stash->currentDie,
 554                        stash->debug_section_end))
 555         return false;
 556
 557       if (aDieInfo.tag == TAG_compile_unit)
 558         {
 559           struct dwarf1_unit* aUnit
 560             = alloc_dwarf1_unit (stash);
 561           if (!aUnit)
 562             return false;
 563
 564           aUnit->name = aDieInfo.name;
 565           aUnit->low_pc = aDieInfo.low_pc;
 566           aUnit->high_pc = aDieInfo.high_pc;
 567           aUnit->has_stmt_list = aDieInfo.has_stmt_list;
 568           aUnit->stmt_list_offset = aDieInfo.stmt_list_offset;
 569
 570           /* A die has a child if it's followed by a die that is
 571              not it's sibling.  */
 572           if (aDieInfo.sibling
 573               && stash->currentDie + aDieInfo.length
 574                     < stash->debug_section_end
 575               && stash->currentDie + aDieInfo.length
 576                     != stash->debug_section + aDieInfo.sibling)
 577             aUnit->first_child = stash->currentDie + aDieInfo.length;
 578           else
 579             aUnit->first_child = 0;
 580
 581           if (aUnit->low_pc <= addr && addr < aUnit->high_pc)
 582             return dwarf1_unit_find_nearest_line (stash, aUnit, addr,
 583                                                   filename_ptr,
 584                                                   functionname_ptr,
 585                                                   linenumber_ptr);
 586         }
 587
 588       if (aDieInfo.sibling != 0)
 589         stash->currentDie = stash->debug_section + aDieInfo.sibling;
 590       else
 591         stash->currentDie += aDieInfo.length;
 592     }
 593
 594   return false;
 595 }
 596
 597 void
 598 _bfd_dwarf1_cleanup_debug_info (bfd *abfd ATTRIBUTE_UNUSED, void **pinfo)
 599 {
 600   struct dwarf1_debug* stash = *pinfo;
 601
 602   if (stash == NULL)
 603     return;
 604
 605   free (stash->debug_section);
 606   free (stash->line_section);
 607 }