1 /* GDB routines for manipulating the minimal symbol tables. 2 Copyright 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 3 2002, 2003, 2004 4 Free Software Foundation, Inc. 5 Contributed by Cygnus Support, using pieces from other GDB modules. 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 2 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, write to the Free Software 21 Foundation, Inc., 59 Temple Place - Suite 330, 22 Boston, MA 02111-1307, USA. */ 23 24 25 /* This file contains support routines for creating, manipulating, and 26 destroying minimal symbol tables. 27 28 Minimal symbol tables are used to hold some very basic information about 29 all defined global symbols (text, data, bss, abs, etc). The only two 30 required pieces of information are the symbol's name and the address 31 associated with that symbol. 32 33 In many cases, even if a file was compiled with no special options for 34 debugging at all, as long as was not stripped it will contain sufficient 35 information to build useful minimal symbol tables using this structure. 36 37 Even when a file contains enough debugging information to build a full 38 symbol table, these minimal symbols are still useful for quickly mapping 39 between names and addresses, and vice versa. They are also sometimes used 40 to figure out what full symbol table entries need to be read in. */ 41 42 43 #include "defs.h" 44 #include <ctype.h> 45 #include "gdb_string.h" 46 #include "symtab.h" 47 #include "bfd.h" 48 #include "symfile.h" 49 #include "objfiles.h" 50 #include "demangle.h" 51 #include "value.h" 52 #include "cp-abi.h" 53 54 /* Accumulate the minimal symbols for each objfile in bunches of BUNCH_SIZE. 55 At the end, copy them all into one newly allocated location on an objfile's 56 symbol obstack. */ 57 58 #define BUNCH_SIZE 127 59 60 struct msym_bunch 61 { 62 struct msym_bunch *next; 63 struct minimal_symbol contents[BUNCH_SIZE]; 64 }; 65 66 /* Bunch currently being filled up. 67 The next field points to chain of filled bunches. */ 68 69 static struct msym_bunch *msym_bunch; 70 71 /* Number of slots filled in current bunch. */ 72 73 static int msym_bunch_index; 74 75 /* Total number of minimal symbols recorded so far for the objfile. */ 76 77 static int msym_count; 78 79 /* Compute a hash code based using the same criteria as `strcmp_iw'. */ 80 81 unsigned int 82 msymbol_hash_iw (const char *string) 83 { 84 unsigned int hash = 0; 85 while (*string && *string != '(') 86 { 87 while (isspace (*string)) 88 ++string; 89 if (*string && *string != '(') 90 { 91 hash = hash * 67 + *string - 113; 92 ++string; 93 } 94 } 95 return hash; 96 } 97 98 /* Compute a hash code for a string. */ 99 100 unsigned int 101 msymbol_hash (const char *string) 102 { 103 unsigned int hash = 0; 104 for (; *string; ++string) 105 hash = hash * 67 + *string - 113; 106 return hash; 107 } 108 109 /* Add the minimal symbol SYM to an objfile's minsym hash table, TABLE. */ 110 void 111 add_minsym_to_hash_table (struct minimal_symbol *sym, 112 struct minimal_symbol **table) 113 { 114 if (sym->hash_next == NULL) 115 { 116 unsigned int hash 117 = msymbol_hash (SYMBOL_LINKAGE_NAME (sym)) % MINIMAL_SYMBOL_HASH_SIZE; 118 sym->hash_next = table[hash]; 119 table[hash] = sym; 120 } 121 } 122 123 /* Add the minimal symbol SYM to an objfile's minsym demangled hash table, 124 TABLE. */ 125 static void 126 add_minsym_to_demangled_hash_table (struct minimal_symbol *sym, 127 struct minimal_symbol **table) 128 { 129 if (sym->demangled_hash_next == NULL) 130 { 131 unsigned int hash = msymbol_hash_iw (SYMBOL_DEMANGLED_NAME (sym)) % MINIMAL_SYMBOL_HASH_SIZE; 132 sym->demangled_hash_next = table[hash]; 133 table[hash] = sym; 134 } 135 } 136 137 138 /* Look through all the current minimal symbol tables and find the 139 first minimal symbol that matches NAME. If OBJF is non-NULL, limit 140 the search to that objfile. If SFILE is non-NULL, the only file-scope 141 symbols considered will be from that source file (global symbols are 142 still preferred). Returns a pointer to the minimal symbol that 143 matches, or NULL if no match is found. 144 145 Note: One instance where there may be duplicate minimal symbols with 146 the same name is when the symbol tables for a shared library and the 147 symbol tables for an executable contain global symbols with the same 148 names (the dynamic linker deals with the duplication). 149 150 It's also possible to have minimal symbols with different mangled 151 names, but identical demangled names. For example, the GNU C++ v3 152 ABI requires the generation of two (or perhaps three) copies of 153 constructor functions --- "in-charge", "not-in-charge", and 154 "allocate" copies; destructors may be duplicated as well. 155 Obviously, there must be distinct mangled names for each of these, 156 but the demangled names are all the same: S::S or S::~S. */ 157 158 struct minimal_symbol * 159 lookup_minimal_symbol (const char *name, const char *sfile, 160 struct objfile *objf) 161 { 162 struct objfile *objfile; 163 struct minimal_symbol *msymbol; 164 struct minimal_symbol *found_symbol = NULL; 165 struct minimal_symbol *found_file_symbol = NULL; 166 struct minimal_symbol *trampoline_symbol = NULL; 167 168 unsigned int hash = msymbol_hash (name) % MINIMAL_SYMBOL_HASH_SIZE; 169 unsigned int dem_hash = msymbol_hash_iw (name) % MINIMAL_SYMBOL_HASH_SIZE; 170 171 #ifdef SOFUN_ADDRESS_MAYBE_MISSING 172 if (sfile != NULL) 173 { 174 char *p = strrchr (sfile, '/'); 175 if (p != NULL) 176 sfile = p + 1; 177 } 178 #endif 179 180 for (objfile = object_files; 181 objfile != NULL && found_symbol == NULL; 182 objfile = objfile->next) 183 { 184 if (objf == NULL || objf == objfile) 185 { 186 /* Do two passes: the first over the ordinary hash table, 187 and the second over the demangled hash table. */ 188 int pass; 189 190 for (pass = 1; pass <= 2 && found_symbol == NULL; pass++) 191 { 192 /* Select hash list according to pass. */ 193 if (pass == 1) 194 msymbol = objfile->msymbol_hash[hash]; 195 else 196 msymbol = objfile->msymbol_demangled_hash[dem_hash]; 197 198 while (msymbol != NULL && found_symbol == NULL) 199 { 200 /* FIXME: carlton/2003-02-27: This is an unholy 201 mixture of linkage names and natural names. If 202 you want to test the linkage names with strcmp, 203 do that. If you want to test the natural names 204 with strcmp_iw, use SYMBOL_MATCHES_NATURAL_NAME. */ 205 if (strcmp (DEPRECATED_SYMBOL_NAME (msymbol), (name)) == 0 206 || (SYMBOL_DEMANGLED_NAME (msymbol) != NULL 207 && strcmp_iw (SYMBOL_DEMANGLED_NAME (msymbol), 208 (name)) == 0)) 209 { 210 switch (MSYMBOL_TYPE (msymbol)) 211 { 212 case mst_file_text: 213 case mst_file_data: 214 case mst_file_bss: 215 #ifdef SOFUN_ADDRESS_MAYBE_MISSING 216 if (sfile == NULL 217 || strcmp (msymbol->filename, sfile) == 0) 218 found_file_symbol = msymbol; 219 #else 220 /* We have neither the ability nor the need to 221 deal with the SFILE parameter. If we find 222 more than one symbol, just return the latest 223 one (the user can't expect useful behavior in 224 that case). */ 225 found_file_symbol = msymbol; 226 #endif 227 break; 228 229 case mst_solib_trampoline: 230 231 /* If a trampoline symbol is found, we prefer to 232 keep looking for the *real* symbol. If the 233 actual symbol is not found, then we'll use the 234 trampoline entry. */ 235 if (trampoline_symbol == NULL) 236 trampoline_symbol = msymbol; 237 break; 238 239 case mst_unknown: 240 default: 241 found_symbol = msymbol; 242 break; 243 } 244 } 245 246 /* Find the next symbol on the hash chain. */ 247 if (pass == 1) 248 msymbol = msymbol->hash_next; 249 else 250 msymbol = msymbol->demangled_hash_next; 251 } 252 } 253 } 254 } 255 /* External symbols are best. */ 256 if (found_symbol) 257 return found_symbol; 258 259 /* File-local symbols are next best. */ 260 if (found_file_symbol) 261 return found_file_symbol; 262 263 /* Symbols for shared library trampolines are next best. */ 264 if (trampoline_symbol) 265 return trampoline_symbol; 266 267 return NULL; 268 } 269 270 /* Look through all the current minimal symbol tables and find the 271 first minimal symbol that matches NAME and has text type. If OBJF 272 is non-NULL, limit the search to that objfile. Returns a pointer 273 to the minimal symbol that matches, or NULL if no match is found. 274 275 This function only searches the mangled (linkage) names. */ 276 277 struct minimal_symbol * 278 lookup_minimal_symbol_text (const char *name, struct objfile *objf) 279 { 280 struct objfile *objfile; 281 struct minimal_symbol *msymbol; 282 struct minimal_symbol *found_symbol = NULL; 283 struct minimal_symbol *found_file_symbol = NULL; 284 285 unsigned int hash = msymbol_hash (name) % MINIMAL_SYMBOL_HASH_SIZE; 286 287 for (objfile = object_files; 288 objfile != NULL && found_symbol == NULL; 289 objfile = objfile->next) 290 { 291 if (objf == NULL || objf == objfile) 292 { 293 for (msymbol = objfile->msymbol_hash[hash]; 294 msymbol != NULL && found_symbol == NULL; 295 msymbol = msymbol->hash_next) 296 { 297 if (strcmp (SYMBOL_LINKAGE_NAME (msymbol), name) == 0 && 298 (MSYMBOL_TYPE (msymbol) == mst_text || 299 MSYMBOL_TYPE (msymbol) == mst_file_text)) 300 { 301 switch (MSYMBOL_TYPE (msymbol)) 302 { 303 case mst_file_text: 304 found_file_symbol = msymbol; 305 break; 306 default: 307 found_symbol = msymbol; 308 break; 309 } 310 } 311 } 312 } 313 } 314 /* External symbols are best. */ 315 if (found_symbol) 316 return found_symbol; 317 318 /* File-local symbols are next best. */ 319 if (found_file_symbol) 320 return found_file_symbol; 321 322 return NULL; 323 } 324 325 /* Look through all the current minimal symbol tables and find the 326 first minimal symbol that matches NAME and is a solib trampoline. 327 If OBJF is non-NULL, limit the search to that objfile. Returns a 328 pointer to the minimal symbol that matches, or NULL if no match is 329 found. 330 331 This function only searches the mangled (linkage) names. */ 332 333 struct minimal_symbol * 334 lookup_minimal_symbol_solib_trampoline (const char *name, 335 struct objfile *objf) 336 { 337 struct objfile *objfile; 338 struct minimal_symbol *msymbol; 339 struct minimal_symbol *found_symbol = NULL; 340 341 unsigned int hash = msymbol_hash (name) % MINIMAL_SYMBOL_HASH_SIZE; 342 343 for (objfile = object_files; 344 objfile != NULL && found_symbol == NULL; 345 objfile = objfile->next) 346 { 347 if (objf == NULL || objf == objfile) 348 { 349 for (msymbol = objfile->msymbol_hash[hash]; 350 msymbol != NULL && found_symbol == NULL; 351 msymbol = msymbol->hash_next) 352 { 353 if (strcmp (SYMBOL_LINKAGE_NAME (msymbol), name) == 0 && 354 MSYMBOL_TYPE (msymbol) == mst_solib_trampoline) 355 return msymbol; 356 } 357 } 358 } 359 360 return NULL; 361 } 362 363 364 /* Search through the minimal symbol table for each objfile and find 365 the symbol whose address is the largest address that is still less 366 than or equal to PC, and matches SECTION (if non-NULL). Returns a 367 pointer to the minimal symbol if such a symbol is found, or NULL if 368 PC is not in a suitable range. Note that we need to look through 369 ALL the minimal symbol tables before deciding on the symbol that 370 comes closest to the specified PC. This is because objfiles can 371 overlap, for example objfile A has .text at 0x100 and .data at 372 0x40000 and objfile B has .text at 0x234 and .data at 0x40048. */ 373 374 struct minimal_symbol * 375 lookup_minimal_symbol_by_pc_section (CORE_ADDR pc, asection *section) 376 { 377 int lo; 378 int hi; 379 int new; 380 struct objfile *objfile; 381 struct minimal_symbol *msymbol; 382 struct minimal_symbol *best_symbol = NULL; 383 struct obj_section *pc_section; 384 385 /* PC has to be in a known section. This ensures that anything 386 beyond the end of the last segment doesn't appear to be part of 387 the last function in the last segment. */ 388 pc_section = find_pc_section (pc); 389 if (pc_section == NULL) 390 return NULL; 391 392 /* NOTE: cagney/2004-01-27: Removed code (added 2003-07-19) that was 393 trying to force the PC into a valid section as returned by 394 find_pc_section. It broke IRIX 6.5 mdebug which relies on this 395 code returning an absolute symbol - the problem was that 396 find_pc_section wasn't returning an absolute section and hence 397 the code below would skip over absolute symbols. Since the 398 original problem was with finding a frame's function, and that 399 uses [indirectly] lookup_minimal_symbol_by_pc, the original 400 problem has been fixed by having that function use 401 find_pc_section. */ 402 403 for (objfile = object_files; 404 objfile != NULL; 405 objfile = objfile->next) 406 { 407 /* If this objfile has a minimal symbol table, go search it using 408 a binary search. Note that a minimal symbol table always consists 409 of at least two symbols, a "real" symbol and the terminating 410 "null symbol". If there are no real symbols, then there is no 411 minimal symbol table at all. */ 412 413 if (objfile->minimal_symbol_count > 0) 414 { 415 msymbol = objfile->msymbols; 416 lo = 0; 417 hi = objfile->minimal_symbol_count - 1; 418 419 /* This code assumes that the minimal symbols are sorted by 420 ascending address values. If the pc value is greater than or 421 equal to the first symbol's address, then some symbol in this 422 minimal symbol table is a suitable candidate for being the 423 "best" symbol. This includes the last real symbol, for cases 424 where the pc value is larger than any address in this vector. 425 426 By iterating until the address associated with the current 427 hi index (the endpoint of the test interval) is less than 428 or equal to the desired pc value, we accomplish two things: 429 (1) the case where the pc value is larger than any minimal 430 symbol address is trivially solved, (2) the address associated 431 with the hi index is always the one we want when the interation 432 terminates. In essence, we are iterating the test interval 433 down until the pc value is pushed out of it from the high end. 434 435 Warning: this code is trickier than it would appear at first. */ 436 437 /* Should also require that pc is <= end of objfile. FIXME! */ 438 if (pc >= SYMBOL_VALUE_ADDRESS (&msymbol[lo])) 439 { 440 while (SYMBOL_VALUE_ADDRESS (&msymbol[hi]) > pc) 441 { 442 /* pc is still strictly less than highest address */ 443 /* Note "new" will always be >= lo */ 444 new = (lo + hi) / 2; 445 if ((SYMBOL_VALUE_ADDRESS (&msymbol[new]) >= pc) || 446 (lo == new)) 447 { 448 hi = new; 449 } 450 else 451 { 452 lo = new; 453 } 454 } 455 456 /* If we have multiple symbols at the same address, we want 457 hi to point to the last one. That way we can find the 458 right symbol if it has an index greater than hi. */ 459 while (hi < objfile->minimal_symbol_count - 1 460 && (SYMBOL_VALUE_ADDRESS (&msymbol[hi]) 461 == SYMBOL_VALUE_ADDRESS (&msymbol[hi + 1]))) 462 hi++; 463 464 /* The minimal symbol indexed by hi now is the best one in this 465 objfile's minimal symbol table. See if it is the best one 466 overall. */ 467 468 /* Skip any absolute symbols. This is apparently what adb 469 and dbx do, and is needed for the CM-5. There are two 470 known possible problems: (1) on ELF, apparently end, edata, 471 etc. are absolute. Not sure ignoring them here is a big 472 deal, but if we want to use them, the fix would go in 473 elfread.c. (2) I think shared library entry points on the 474 NeXT are absolute. If we want special handling for this 475 it probably should be triggered by a special 476 mst_abs_or_lib or some such. */ 477 while (hi >= 0 478 && msymbol[hi].type == mst_abs) 479 --hi; 480 481 /* If "section" specified, skip any symbol from wrong section */ 482 /* This is the new code that distinguishes it from the old function */ 483 if (section) 484 while (hi >= 0 485 /* Some types of debug info, such as COFF, 486 don't fill the bfd_section member, so don't 487 throw away symbols on those platforms. */ 488 && SYMBOL_BFD_SECTION (&msymbol[hi]) != NULL 489 && SYMBOL_BFD_SECTION (&msymbol[hi]) != section) 490 --hi; 491 492 if (hi >= 0 493 && ((best_symbol == NULL) || 494 (SYMBOL_VALUE_ADDRESS (best_symbol) < 495 SYMBOL_VALUE_ADDRESS (&msymbol[hi])))) 496 { 497 best_symbol = &msymbol[hi]; 498 } 499 } 500 } 501 } 502 return (best_symbol); 503 } 504 505 /* Backward compatibility: search through the minimal symbol table 506 for a matching PC (no section given) */ 507 508 struct minimal_symbol * 509 lookup_minimal_symbol_by_pc (CORE_ADDR pc) 510 { 511 /* NOTE: cagney/2004-01-27: This was using find_pc_mapped_section to 512 force the section but that (well unless you're doing overlay 513 debugging) always returns NULL making the call somewhat useless. */ 514 struct obj_section *section = find_pc_section (pc); 515 if (section == NULL) 516 return NULL; 517 return lookup_minimal_symbol_by_pc_section (pc, section->the_bfd_section); 518 } 519 520 521 /* Return leading symbol character for a BFD. If BFD is NULL, 522 return the leading symbol character from the main objfile. */ 523 524 static int get_symbol_leading_char (bfd *); 525 526 static int 527 get_symbol_leading_char (bfd *abfd) 528 { 529 if (abfd != NULL) 530 return bfd_get_symbol_leading_char (abfd); 531 if (symfile_objfile != NULL && symfile_objfile->obfd != NULL) 532 return bfd_get_symbol_leading_char (symfile_objfile->obfd); 533 return 0; 534 } 535 536 /* Prepare to start collecting minimal symbols. Note that presetting 537 msym_bunch_index to BUNCH_SIZE causes the first call to save a minimal 538 symbol to allocate the memory for the first bunch. */ 539 540 void 541 init_minimal_symbol_collection (void) 542 { 543 msym_count = 0; 544 msym_bunch = NULL; 545 msym_bunch_index = BUNCH_SIZE; 546 } 547 548 void 549 prim_record_minimal_symbol (const char *name, CORE_ADDR address, 550 enum minimal_symbol_type ms_type, 551 struct objfile *objfile) 552 { 553 int section; 554 555 switch (ms_type) 556 { 557 case mst_text: 558 case mst_file_text: 559 case mst_solib_trampoline: 560 section = SECT_OFF_TEXT (objfile); 561 break; 562 case mst_data: 563 case mst_file_data: 564 section = SECT_OFF_DATA (objfile); 565 break; 566 case mst_bss: 567 case mst_file_bss: 568 section = SECT_OFF_BSS (objfile); 569 break; 570 default: 571 section = -1; 572 } 573 574 prim_record_minimal_symbol_and_info (name, address, ms_type, 575 NULL, section, NULL, objfile); 576 } 577 578 /* Record a minimal symbol in the msym bunches. Returns the symbol 579 newly created. */ 580 581 struct minimal_symbol * 582 prim_record_minimal_symbol_and_info (const char *name, CORE_ADDR address, 583 enum minimal_symbol_type ms_type, 584 char *info, int section, 585 asection *bfd_section, 586 struct objfile *objfile) 587 { 588 struct msym_bunch *new; 589 struct minimal_symbol *msymbol; 590 591 /* Don't put gcc_compiled, __gnu_compiled_cplus, and friends into 592 the minimal symbols, because if there is also another symbol 593 at the same address (e.g. the first function of the file), 594 lookup_minimal_symbol_by_pc would have no way of getting the 595 right one. */ 596 if (ms_type == mst_file_text && name[0] == 'g' 597 && (strcmp (name, GCC_COMPILED_FLAG_SYMBOL) == 0 598 || strcmp (name, GCC2_COMPILED_FLAG_SYMBOL) == 0)) 599 return (NULL); 600 601 /* It's safe to strip the leading char here once, since the name 602 is also stored stripped in the minimal symbol table. */ 603 if (name[0] == get_symbol_leading_char (objfile->obfd)) 604 ++name; 605 606 if (ms_type == mst_file_text && strncmp (name, "__gnu_compiled", 14) == 0) 607 return (NULL); 608 609 if (msym_bunch_index == BUNCH_SIZE) 610 { 611 new = (struct msym_bunch *) xmalloc (sizeof (struct msym_bunch)); 612 msym_bunch_index = 0; 613 new->next = msym_bunch; 614 msym_bunch = new; 615 } 616 msymbol = &msym_bunch->contents[msym_bunch_index]; 617 SYMBOL_INIT_LANGUAGE_SPECIFIC (msymbol, language_unknown); 618 SYMBOL_LANGUAGE (msymbol) = language_auto; 619 SYMBOL_SET_NAMES (msymbol, (char *)name, strlen (name), objfile); 620 621 SYMBOL_VALUE_ADDRESS (msymbol) = address; 622 SYMBOL_SECTION (msymbol) = section; 623 SYMBOL_BFD_SECTION (msymbol) = bfd_section; 624 625 MSYMBOL_TYPE (msymbol) = ms_type; 626 /* FIXME: This info, if it remains, needs its own field. */ 627 MSYMBOL_INFO (msymbol) = info; /* FIXME! */ 628 MSYMBOL_SIZE (msymbol) = 0; 629 630 /* The hash pointers must be cleared! If they're not, 631 add_minsym_to_hash_table will NOT add this msymbol to the hash table. */ 632 msymbol->hash_next = NULL; 633 msymbol->demangled_hash_next = NULL; 634 635 msym_bunch_index++; 636 msym_count++; 637 OBJSTAT (objfile, n_minsyms++); 638 return msymbol; 639 } 640 641 /* Compare two minimal symbols by address and return a signed result based 642 on unsigned comparisons, so that we sort into unsigned numeric order. 643 Within groups with the same address, sort by name. */ 644 645 static int 646 compare_minimal_symbols (const void *fn1p, const void *fn2p) 647 { 648 const struct minimal_symbol *fn1; 649 const struct minimal_symbol *fn2; 650 651 fn1 = (const struct minimal_symbol *) fn1p; 652 fn2 = (const struct minimal_symbol *) fn2p; 653 654 if (SYMBOL_VALUE_ADDRESS (fn1) < SYMBOL_VALUE_ADDRESS (fn2)) 655 { 656 return (-1); /* addr 1 is less than addr 2 */ 657 } 658 else if (SYMBOL_VALUE_ADDRESS (fn1) > SYMBOL_VALUE_ADDRESS (fn2)) 659 { 660 return (1); /* addr 1 is greater than addr 2 */ 661 } 662 else 663 /* addrs are equal: sort by name */ 664 { 665 char *name1 = SYMBOL_LINKAGE_NAME (fn1); 666 char *name2 = SYMBOL_LINKAGE_NAME (fn2); 667 668 if (name1 && name2) /* both have names */ 669 return strcmp (name1, name2); 670 else if (name2) 671 return 1; /* fn1 has no name, so it is "less" */ 672 else if (name1) /* fn2 has no name, so it is "less" */ 673 return -1; 674 else 675 return (0); /* neither has a name, so they're equal. */ 676 } 677 } 678 679 /* Discard the currently collected minimal symbols, if any. If we wish 680 to save them for later use, we must have already copied them somewhere 681 else before calling this function. 682 683 FIXME: We could allocate the minimal symbol bunches on their own 684 obstack and then simply blow the obstack away when we are done with 685 it. Is it worth the extra trouble though? */ 686 687 static void 688 do_discard_minimal_symbols_cleanup (void *arg) 689 { 690 struct msym_bunch *next; 691 692 while (msym_bunch != NULL) 693 { 694 next = msym_bunch->next; 695 xfree (msym_bunch); 696 msym_bunch = next; 697 } 698 } 699 700 struct cleanup * 701 make_cleanup_discard_minimal_symbols (void) 702 { 703 return make_cleanup (do_discard_minimal_symbols_cleanup, 0); 704 } 705 706 707 708 /* Compact duplicate entries out of a minimal symbol table by walking 709 through the table and compacting out entries with duplicate addresses 710 and matching names. Return the number of entries remaining. 711 712 On entry, the table resides between msymbol[0] and msymbol[mcount]. 713 On exit, it resides between msymbol[0] and msymbol[result_count]. 714 715 When files contain multiple sources of symbol information, it is 716 possible for the minimal symbol table to contain many duplicate entries. 717 As an example, SVR4 systems use ELF formatted object files, which 718 usually contain at least two different types of symbol tables (a 719 standard ELF one and a smaller dynamic linking table), as well as 720 DWARF debugging information for files compiled with -g. 721 722 Without compacting, the minimal symbol table for gdb itself contains 723 over a 1000 duplicates, about a third of the total table size. Aside 724 from the potential trap of not noticing that two successive entries 725 identify the same location, this duplication impacts the time required 726 to linearly scan the table, which is done in a number of places. So we 727 just do one linear scan here and toss out the duplicates. 728 729 Note that we are not concerned here about recovering the space that 730 is potentially freed up, because the strings themselves are allocated 731 on the objfile_obstack, and will get automatically freed when the symbol 732 table is freed. The caller can free up the unused minimal symbols at 733 the end of the compacted region if their allocation strategy allows it. 734 735 Also note we only go up to the next to last entry within the loop 736 and then copy the last entry explicitly after the loop terminates. 737 738 Since the different sources of information for each symbol may 739 have different levels of "completeness", we may have duplicates 740 that have one entry with type "mst_unknown" and the other with a 741 known type. So if the one we are leaving alone has type mst_unknown, 742 overwrite its type with the type from the one we are compacting out. */ 743 744 static int 745 compact_minimal_symbols (struct minimal_symbol *msymbol, int mcount, 746 struct objfile *objfile) 747 { 748 struct minimal_symbol *copyfrom; 749 struct minimal_symbol *copyto; 750 751 if (mcount > 0) 752 { 753 copyfrom = copyto = msymbol; 754 while (copyfrom < msymbol + mcount - 1) 755 { 756 if (SYMBOL_VALUE_ADDRESS (copyfrom) 757 == SYMBOL_VALUE_ADDRESS ((copyfrom + 1)) 758 && strcmp (SYMBOL_LINKAGE_NAME (copyfrom), 759 SYMBOL_LINKAGE_NAME ((copyfrom + 1))) == 0) 760 { 761 if (MSYMBOL_TYPE ((copyfrom + 1)) == mst_unknown) 762 { 763 MSYMBOL_TYPE ((copyfrom + 1)) = MSYMBOL_TYPE (copyfrom); 764 } 765 copyfrom++; 766 } 767 else 768 *copyto++ = *copyfrom++; 769 } 770 *copyto++ = *copyfrom++; 771 mcount = copyto - msymbol; 772 } 773 return (mcount); 774 } 775 776 /* Build (or rebuild) the minimal symbol hash tables. This is necessary 777 after compacting or sorting the table since the entries move around 778 thus causing the internal minimal_symbol pointers to become jumbled. */ 779 780 static void 781 build_minimal_symbol_hash_tables (struct objfile *objfile) 782 { 783 int i; 784 struct minimal_symbol *msym; 785 786 /* Clear the hash tables. */ 787 for (i = 0; i < MINIMAL_SYMBOL_HASH_SIZE; i++) 788 { 789 objfile->msymbol_hash[i] = 0; 790 objfile->msymbol_demangled_hash[i] = 0; 791 } 792 793 /* Now, (re)insert the actual entries. */ 794 for (i = objfile->minimal_symbol_count, msym = objfile->msymbols; 795 i > 0; 796 i--, msym++) 797 { 798 msym->hash_next = 0; 799 add_minsym_to_hash_table (msym, objfile->msymbol_hash); 800 801 msym->demangled_hash_next = 0; 802 if (SYMBOL_SEARCH_NAME (msym) != SYMBOL_LINKAGE_NAME (msym)) 803 add_minsym_to_demangled_hash_table (msym, 804 objfile->msymbol_demangled_hash); 805 } 806 } 807 808 /* Add the minimal symbols in the existing bunches to the objfile's official 809 minimal symbol table. In most cases there is no minimal symbol table yet 810 for this objfile, and the existing bunches are used to create one. Once 811 in a while (for shared libraries for example), we add symbols (e.g. common 812 symbols) to an existing objfile. 813 814 Because of the way minimal symbols are collected, we generally have no way 815 of knowing what source language applies to any particular minimal symbol. 816 Specifically, we have no way of knowing if the minimal symbol comes from a 817 C++ compilation unit or not. So for the sake of supporting cached 818 demangled C++ names, we have no choice but to try and demangle each new one 819 that comes in. If the demangling succeeds, then we assume it is a C++ 820 symbol and set the symbol's language and demangled name fields 821 appropriately. Note that in order to avoid unnecessary demanglings, and 822 allocating obstack space that subsequently can't be freed for the demangled 823 names, we mark all newly added symbols with language_auto. After 824 compaction of the minimal symbols, we go back and scan the entire minimal 825 symbol table looking for these new symbols. For each new symbol we attempt 826 to demangle it, and if successful, record it as a language_cplus symbol 827 and cache the demangled form on the symbol obstack. Symbols which don't 828 demangle are marked as language_unknown symbols, which inhibits future 829 attempts to demangle them if we later add more minimal symbols. */ 830 831 void 832 install_minimal_symbols (struct objfile *objfile) 833 { 834 int bindex; 835 int mcount; 836 struct msym_bunch *bunch; 837 struct minimal_symbol *msymbols; 838 int alloc_count; 839 840 if (msym_count > 0) 841 { 842 /* Allocate enough space in the obstack, into which we will gather the 843 bunches of new and existing minimal symbols, sort them, and then 844 compact out the duplicate entries. Once we have a final table, 845 we will give back the excess space. */ 846 847 alloc_count = msym_count + objfile->minimal_symbol_count + 1; 848 obstack_blank (&objfile->objfile_obstack, 849 alloc_count * sizeof (struct minimal_symbol)); 850 msymbols = (struct minimal_symbol *) 851 obstack_base (&objfile->objfile_obstack); 852 853 /* Copy in the existing minimal symbols, if there are any. */ 854 855 if (objfile->minimal_symbol_count) 856 memcpy ((char *) msymbols, (char *) objfile->msymbols, 857 objfile->minimal_symbol_count * sizeof (struct minimal_symbol)); 858 859 /* Walk through the list of minimal symbol bunches, adding each symbol 860 to the new contiguous array of symbols. Note that we start with the 861 current, possibly partially filled bunch (thus we use the current 862 msym_bunch_index for the first bunch we copy over), and thereafter 863 each bunch is full. */ 864 865 mcount = objfile->minimal_symbol_count; 866 867 for (bunch = msym_bunch; bunch != NULL; bunch = bunch->next) 868 { 869 for (bindex = 0; bindex < msym_bunch_index; bindex++, mcount++) 870 msymbols[mcount] = bunch->contents[bindex]; 871 msym_bunch_index = BUNCH_SIZE; 872 } 873 874 /* Sort the minimal symbols by address. */ 875 876 qsort (msymbols, mcount, sizeof (struct minimal_symbol), 877 compare_minimal_symbols); 878 879 /* Compact out any duplicates, and free up whatever space we are 880 no longer using. */ 881 882 mcount = compact_minimal_symbols (msymbols, mcount, objfile); 883 884 obstack_blank (&objfile->objfile_obstack, 885 (mcount + 1 - alloc_count) * sizeof (struct minimal_symbol)); 886 msymbols = (struct minimal_symbol *) 887 obstack_finish (&objfile->objfile_obstack); 888 889 /* We also terminate the minimal symbol table with a "null symbol", 890 which is *not* included in the size of the table. This makes it 891 easier to find the end of the table when we are handed a pointer 892 to some symbol in the middle of it. Zero out the fields in the 893 "null symbol" allocated at the end of the array. Note that the 894 symbol count does *not* include this null symbol, which is why it 895 is indexed by mcount and not mcount-1. */ 896 897 SYMBOL_LINKAGE_NAME (&msymbols[mcount]) = NULL; 898 SYMBOL_VALUE_ADDRESS (&msymbols[mcount]) = 0; 899 MSYMBOL_INFO (&msymbols[mcount]) = NULL; 900 MSYMBOL_SIZE (&msymbols[mcount]) = 0; 901 MSYMBOL_TYPE (&msymbols[mcount]) = mst_unknown; 902 SYMBOL_INIT_LANGUAGE_SPECIFIC (&msymbols[mcount], language_unknown); 903 904 /* Attach the minimal symbol table to the specified objfile. 905 The strings themselves are also located in the objfile_obstack 906 of this objfile. */ 907 908 objfile->minimal_symbol_count = mcount; 909 objfile->msymbols = msymbols; 910 911 /* Try to guess the appropriate C++ ABI by looking at the names 912 of the minimal symbols in the table. */ 913 { 914 int i; 915 916 for (i = 0; i < mcount; i++) 917 { 918 /* If a symbol's name starts with _Z and was successfully 919 demangled, then we can assume we've found a GNU v3 symbol. 920 For now we set the C++ ABI globally; if the user is 921 mixing ABIs then the user will need to "set cp-abi" 922 manually. */ 923 const char *name = SYMBOL_LINKAGE_NAME (&objfile->msymbols[i]); 924 if (name[0] == '_' && name[1] == 'Z' 925 && SYMBOL_DEMANGLED_NAME (&objfile->msymbols[i]) != NULL) 926 { 927 set_cp_abi_as_auto_default ("gnu-v3"); 928 break; 929 } 930 } 931 } 932 933 /* Now build the hash tables; we can't do this incrementally 934 at an earlier point since we weren't finished with the obstack 935 yet. (And if the msymbol obstack gets moved, all the internal 936 pointers to other msymbols need to be adjusted.) */ 937 build_minimal_symbol_hash_tables (objfile); 938 } 939 } 940 941 /* Sort all the minimal symbols in OBJFILE. */ 942 943 void 944 msymbols_sort (struct objfile *objfile) 945 { 946 qsort (objfile->msymbols, objfile->minimal_symbol_count, 947 sizeof (struct minimal_symbol), compare_minimal_symbols); 948 build_minimal_symbol_hash_tables (objfile); 949 } 950 951 /* Check if PC is in a shared library trampoline code stub. 952 Return minimal symbol for the trampoline entry or NULL if PC is not 953 in a trampoline code stub. */ 954 955 struct minimal_symbol * 956 lookup_solib_trampoline_symbol_by_pc (CORE_ADDR pc) 957 { 958 struct minimal_symbol *msymbol = lookup_minimal_symbol_by_pc (pc); 959 960 if (msymbol != NULL && MSYMBOL_TYPE (msymbol) == mst_solib_trampoline) 961 return msymbol; 962 return NULL; 963 } 964 965 /* If PC is in a shared library trampoline code stub, return the 966 address of the `real' function belonging to the stub. 967 Return 0 if PC is not in a trampoline code stub or if the real 968 function is not found in the minimal symbol table. 969 970 We may fail to find the right function if a function with the 971 same name is defined in more than one shared library, but this 972 is considered bad programming style. We could return 0 if we find 973 a duplicate function in case this matters someday. */ 974 975 CORE_ADDR 976 find_solib_trampoline_target (CORE_ADDR pc) 977 { 978 struct objfile *objfile; 979 struct minimal_symbol *msymbol; 980 struct minimal_symbol *tsymbol = lookup_solib_trampoline_symbol_by_pc (pc); 981 982 if (tsymbol != NULL) 983 { 984 ALL_MSYMBOLS (objfile, msymbol) 985 { 986 if (MSYMBOL_TYPE (msymbol) == mst_text 987 && strcmp (SYMBOL_LINKAGE_NAME (msymbol), 988 SYMBOL_LINKAGE_NAME (tsymbol)) == 0) 989 return SYMBOL_VALUE_ADDRESS (msymbol); 990 } 991 } 992 return 0; 993 } 994