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 60struct 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 69static struct msym_bunch *msym_bunch; 70 71/* Number of slots filled in current bunch. */ 72 73static int msym_bunch_index; 74 75/* Total number of minimal symbols recorded so far for the objfile. */ 76 77static int msym_count; 78 79/* Compute a hash code based using the same criteria as `strcmp_iw'. */ 80 81unsigned int 82msymbol_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 100unsigned int 101msymbol_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. */ 110void 111add_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. */ 125static void 126add_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 150struct minimal_symbol * 151lookup_minimal_symbol (const char *name, const char *sfile, 152 struct objfile *objf) 153{ 154 struct objfile *objfile; 155 struct minimal_symbol *msymbol; 156 struct minimal_symbol *found_symbol = NULL; 157 struct minimal_symbol *found_file_symbol = NULL; 158 struct minimal_symbol *trampoline_symbol = NULL; 159 160 unsigned int hash = msymbol_hash (name) % MINIMAL_SYMBOL_HASH_SIZE; 161 unsigned int dem_hash = msymbol_hash_iw (name) % MINIMAL_SYMBOL_HASH_SIZE; 162 163#ifdef SOFUN_ADDRESS_MAYBE_MISSING 164 if (sfile != NULL) 165 { 166 char *p = strrchr (sfile, '/'); 167 if (p != NULL) 168 sfile = p + 1; 169 } 170#endif 171 172 for (objfile = object_files; 173 objfile != NULL && found_symbol == NULL; 174 objfile = objfile->next) 175 { 176 if (objf == NULL || objf == objfile) 177 { 178 /* Do two passes: the first over the ordinary hash table, 179 and the second over the demangled hash table. */ 180 int pass; 181 182 for (pass = 1; pass <= 2 && found_symbol == NULL; pass++) 183 { 184 /* Select hash list according to pass. */ 185 if (pass == 1) 186 msymbol = objfile->msymbol_hash[hash]; 187 else 188 msymbol = objfile->msymbol_demangled_hash[dem_hash]; 189 190 while (msymbol != NULL && found_symbol == NULL) 191 { 192 /* FIXME: carlton/2003-02-27: This is an unholy 193 mixture of linkage names and natural names. If 194 you want to test the linkage names with strcmp, 195 do that. If you want to test the natural names 196 with strcmp_iw, use SYMBOL_MATCHES_NATURAL_NAME. */ 197 if (strcmp (DEPRECATED_SYMBOL_NAME (msymbol), (name)) == 0 198 || (SYMBOL_DEMANGLED_NAME (msymbol) != NULL 199 && strcmp_iw (SYMBOL_DEMANGLED_NAME (msymbol), 200 (name)) == 0)) 201 { 202 switch (MSYMBOL_TYPE (msymbol)) 203 { 204 case mst_file_text: 205 case mst_file_data: 206 case mst_file_bss: 207#ifdef SOFUN_ADDRESS_MAYBE_MISSING 208 if (sfile == NULL 209 || strcmp (msymbol->filename, sfile) == 0) 210 found_file_symbol = msymbol; 211#else 212 /* We have neither the ability nor the need to 213 deal with the SFILE parameter. If we find 214 more than one symbol, just return the latest 215 one (the user can't expect useful behavior in 216 that case). */ 217 found_file_symbol = msymbol; 218#endif 219 break; 220 221 case mst_solib_trampoline: 222 223 /* If a trampoline symbol is found, we prefer to 224 keep looking for the *real* symbol. If the 225 actual symbol is not found, then we'll use the 226 trampoline entry. */ 227 if (trampoline_symbol == NULL) 228 trampoline_symbol = msymbol; 229 break; 230 231 case mst_unknown: 232 default: 233 found_symbol = msymbol; 234 break; 235 } 236 } 237 238 /* Find the next symbol on the hash chain. */ 239 if (pass == 1) 240 msymbol = msymbol->hash_next; 241 else 242 msymbol = msymbol->demangled_hash_next; 243 } 244 } 245 } 246 } 247 /* External symbols are best. */ 248 if (found_symbol) 249 return found_symbol; 250 251 /* File-local symbols are next best. */ 252 if (found_file_symbol) 253 return found_file_symbol; 254 255 /* Symbols for shared library trampolines are next best. */ 256 if (trampoline_symbol) 257 return trampoline_symbol; 258 259 return NULL; 260} 261 262/* Look through all the current minimal symbol tables and find the 263 first minimal symbol that matches NAME and has text type. If OBJF 264 is non-NULL, limit the search to that objfile. Returns a pointer 265 to the minimal symbol that matches, or NULL if no match is found. 266 267 This function only searches the mangled (linkage) names. */ 268 269struct minimal_symbol * 270lookup_minimal_symbol_text (const char *name, struct objfile *objf) 271{ 272 struct objfile *objfile; 273 struct minimal_symbol *msymbol; 274 struct minimal_symbol *found_symbol = NULL; 275 struct minimal_symbol *found_file_symbol = NULL; 276 277 unsigned int hash = msymbol_hash (name) % MINIMAL_SYMBOL_HASH_SIZE; 278 279 for (objfile = object_files; 280 objfile != NULL && found_symbol == NULL; 281 objfile = objfile->next) 282 { 283 if (objf == NULL || objf == objfile) 284 { 285 for (msymbol = objfile->msymbol_hash[hash]; 286 msymbol != NULL && found_symbol == NULL; 287 msymbol = msymbol->hash_next) 288 { 289 if (strcmp (SYMBOL_LINKAGE_NAME (msymbol), name) == 0 && 290 (MSYMBOL_TYPE (msymbol) == mst_text || 291 MSYMBOL_TYPE (msymbol) == mst_file_text)) 292 { 293 switch (MSYMBOL_TYPE (msymbol)) 294 { 295 case mst_file_text: 296 found_file_symbol = msymbol; 297 break; 298 default: 299 found_symbol = msymbol; 300 break; 301 } 302 } 303 } 304 } 305 } 306 /* External symbols are best. */ 307 if (found_symbol) 308 return found_symbol; 309 310 /* File-local symbols are next best. */ 311 if (found_file_symbol) 312 return found_file_symbol; 313 314 return NULL; 315} 316 317/* Look through all the current minimal symbol tables and find the 318 first minimal symbol that matches NAME and is a solib trampoline. 319 If OBJF is non-NULL, limit the search to that objfile. Returns a 320 pointer to the minimal symbol that matches, or NULL if no match is 321 found. 322 323 This function only searches the mangled (linkage) names. */ 324 325struct minimal_symbol * 326lookup_minimal_symbol_solib_trampoline (const char *name, 327 struct objfile *objf) 328{ 329 struct objfile *objfile; 330 struct minimal_symbol *msymbol; 331 struct minimal_symbol *found_symbol = NULL; 332 333 unsigned int hash = msymbol_hash (name) % MINIMAL_SYMBOL_HASH_SIZE; 334 335 for (objfile = object_files; 336 objfile != NULL && found_symbol == NULL; 337 objfile = objfile->next) 338 { 339 if (objf == NULL || objf == objfile) 340 { 341 for (msymbol = objfile->msymbol_hash[hash]; 342 msymbol != NULL && found_symbol == NULL; 343 msymbol = msymbol->hash_next) 344 { 345 if (strcmp (SYMBOL_LINKAGE_NAME (msymbol), name) == 0 && 346 MSYMBOL_TYPE (msymbol) == mst_solib_trampoline) 347 return msymbol; 348 } 349 } 350 } 351 352 return NULL; 353} 354 355 356/* Search through the minimal symbol table for each objfile and find 357 the symbol whose address is the largest address that is still less 358 than or equal to PC, and matches SECTION (if non-NULL). Returns a 359 pointer to the minimal symbol if such a symbol is found, or NULL if 360 PC is not in a suitable range. Note that we need to look through 361 ALL the minimal symbol tables before deciding on the symbol that 362 comes closest to the specified PC. This is because objfiles can 363 overlap, for example objfile A has .text at 0x100 and .data at 364 0x40000 and objfile B has .text at 0x234 and .data at 0x40048. */ 365 366struct minimal_symbol * 367lookup_minimal_symbol_by_pc_section (CORE_ADDR pc, asection *section) 368{ 369 int lo; 370 int hi; 371 int new; 372 struct objfile *objfile; 373 struct minimal_symbol *msymbol; 374 struct minimal_symbol *best_symbol = NULL; 375 struct obj_section *pc_section; 376 377 /* PC has to be in a known section. This ensures that anything 378 beyond the end of the last segment doesn't appear to be part of 379 the last function in the last segment. */ 380 pc_section = find_pc_section (pc); 381 if (pc_section == NULL) 382 return NULL; 383 384 /* NOTE: cagney/2004-01-27: Removed code (added 2003-07-19) that was 385 trying to force the PC into a valid section as returned by 386 find_pc_section. It broke IRIX 6.5 mdebug which relies on this 387 code returning an absolute symbol - the problem was that 388 find_pc_section wasn't returning an absolute section and hence 389 the code below would skip over absolute symbols. Since the 390 original problem was with finding a frame's function, and that 391 uses [indirectly] lookup_minimal_symbol_by_pc, the original 392 problem has been fixed by having that function use 393 find_pc_section. */ 394 395 for (objfile = object_files; 396 objfile != NULL; 397 objfile = objfile->next) 398 { 399 /* If this objfile has a minimal symbol table, go search it using 400 a binary search. Note that a minimal symbol table always consists 401 of at least two symbols, a "real" symbol and the terminating 402 "null symbol". If there are no real symbols, then there is no 403 minimal symbol table at all. */ 404 405 if (objfile->minimal_symbol_count > 0) 406 { 407 msymbol = objfile->msymbols; 408 lo = 0; 409 hi = objfile->minimal_symbol_count - 1; 410 411 /* This code assumes that the minimal symbols are sorted by 412 ascending address values. If the pc value is greater than or 413 equal to the first symbol's address, then some symbol in this 414 minimal symbol table is a suitable candidate for being the 415 "best" symbol. This includes the last real symbol, for cases 416 where the pc value is larger than any address in this vector. 417 418 By iterating until the address associated with the current 419 hi index (the endpoint of the test interval) is less than 420 or equal to the desired pc value, we accomplish two things: 421 (1) the case where the pc value is larger than any minimal 422 symbol address is trivially solved, (2) the address associated 423 with the hi index is always the one we want when the interation 424 terminates. In essence, we are iterating the test interval 425 down until the pc value is pushed out of it from the high end. 426 427 Warning: this code is trickier than it would appear at first. */ 428 429 /* Should also require that pc is <= end of objfile. FIXME! */ 430 if (pc >= SYMBOL_VALUE_ADDRESS (&msymbol[lo])) 431 { 432 while (SYMBOL_VALUE_ADDRESS (&msymbol[hi]) > pc) 433 { 434 /* pc is still strictly less than highest address */ 435 /* Note "new" will always be >= lo */ 436 new = (lo + hi) / 2; 437 if ((SYMBOL_VALUE_ADDRESS (&msymbol[new]) >= pc) || 438 (lo == new)) 439 { 440 hi = new; 441 } 442 else 443 { 444 lo = new; 445 } 446 } 447 448 /* If we have multiple symbols at the same address, we want 449 hi to point to the last one. That way we can find the 450 right symbol if it has an index greater than hi. */ 451 while (hi < objfile->minimal_symbol_count - 1 452 && (SYMBOL_VALUE_ADDRESS (&msymbol[hi]) 453 == SYMBOL_VALUE_ADDRESS (&msymbol[hi + 1]))) 454 hi++; 455 456 /* The minimal symbol indexed by hi now is the best one in this 457 objfile's minimal symbol table. See if it is the best one 458 overall. */ 459 460 /* Skip any absolute symbols. This is apparently what adb 461 and dbx do, and is needed for the CM-5. There are two 462 known possible problems: (1) on ELF, apparently end, edata, 463 etc. are absolute. Not sure ignoring them here is a big 464 deal, but if we want to use them, the fix would go in 465 elfread.c. (2) I think shared library entry points on the 466 NeXT are absolute. If we want special handling for this 467 it probably should be triggered by a special 468 mst_abs_or_lib or some such. */ 469 while (hi >= 0 470 && msymbol[hi].type == mst_abs) 471 --hi; 472 473 /* If "section" specified, skip any symbol from wrong section */ 474 /* This is the new code that distinguishes it from the old function */ 475 if (section) 476 while (hi >= 0 477 /* Some types of debug info, such as COFF, 478 don't fill the bfd_section member, so don't 479 throw away symbols on those platforms. */ 480 && SYMBOL_BFD_SECTION (&msymbol[hi]) != NULL 481 && SYMBOL_BFD_SECTION (&msymbol[hi]) != section) 482 --hi; 483 484 if (hi >= 0 485 && ((best_symbol == NULL) || 486 (SYMBOL_VALUE_ADDRESS (best_symbol) < 487 SYMBOL_VALUE_ADDRESS (&msymbol[hi])))) 488 { 489 best_symbol = &msymbol[hi]; 490 } 491 } 492 } 493 } 494 return (best_symbol); 495} 496 497/* Backward compatibility: search through the minimal symbol table 498 for a matching PC (no section given) */ 499 500struct minimal_symbol * 501lookup_minimal_symbol_by_pc (CORE_ADDR pc) 502{ 503 /* NOTE: cagney/2004-01-27: This was using find_pc_mapped_section to 504 force the section but that (well unless you're doing overlay 505 debugging) always returns NULL making the call somewhat useless. */ 506 struct obj_section *section = find_pc_section (pc); 507 if (section == NULL) 508 return NULL; 509 return lookup_minimal_symbol_by_pc_section (pc, section->the_bfd_section); 510} 511 512 513/* Return leading symbol character for a BFD. If BFD is NULL, 514 return the leading symbol character from the main objfile. */ 515 516static int get_symbol_leading_char (bfd *); 517 518static int 519get_symbol_leading_char (bfd *abfd) 520{ 521 if (abfd != NULL) 522 return bfd_get_symbol_leading_char (abfd); 523 if (symfile_objfile != NULL && symfile_objfile->obfd != NULL) 524 return bfd_get_symbol_leading_char (symfile_objfile->obfd); 525 return 0; 526} 527 528/* Prepare to start collecting minimal symbols. Note that presetting 529 msym_bunch_index to BUNCH_SIZE causes the first call to save a minimal 530 symbol to allocate the memory for the first bunch. */ 531 532void 533init_minimal_symbol_collection (void) 534{ 535 msym_count = 0; 536 msym_bunch = NULL; 537 msym_bunch_index = BUNCH_SIZE; 538} 539 540void 541prim_record_minimal_symbol (const char *name, CORE_ADDR address, 542 enum minimal_symbol_type ms_type, 543 struct objfile *objfile) 544{ 545 int section; 546 547 switch (ms_type) 548 { 549 case mst_text: 550 case mst_file_text: 551 case mst_solib_trampoline: 552 section = SECT_OFF_TEXT (objfile); 553 break; 554 case mst_data: 555 case mst_file_data: 556 section = SECT_OFF_DATA (objfile); 557 break; 558 case mst_bss: 559 case mst_file_bss: 560 section = SECT_OFF_BSS (objfile); 561 break; 562 default: 563 section = -1; 564 } 565 566 prim_record_minimal_symbol_and_info (name, address, ms_type, 567 NULL, section, NULL, objfile); 568} 569 570/* Record a minimal symbol in the msym bunches. Returns the symbol 571 newly created. */ 572 573struct minimal_symbol * 574prim_record_minimal_symbol_and_info (const char *name, CORE_ADDR address, 575 enum minimal_symbol_type ms_type, 576 char *info, int section, 577 asection *bfd_section, 578 struct objfile *objfile) 579{ 580 struct msym_bunch *new; 581 struct minimal_symbol *msymbol; 582 583 if (ms_type == mst_file_text) 584 { 585 /* Don't put gcc_compiled, __gnu_compiled_cplus, and friends into 586 the minimal symbols, because if there is also another symbol 587 at the same address (e.g. the first function of the file), 588 lookup_minimal_symbol_by_pc would have no way of getting the 589 right one. */ 590 if (name[0] == 'g' 591 && (strcmp (name, GCC_COMPILED_FLAG_SYMBOL) == 0 592 || strcmp (name, GCC2_COMPILED_FLAG_SYMBOL) == 0)) 593 return (NULL); 594 595 { 596 const char *tempstring = name; 597 if (tempstring[0] == get_symbol_leading_char (objfile->obfd)) 598 ++tempstring; 599 if (strncmp (tempstring, "__gnu_compiled", 14) == 0) 600 return (NULL); 601 } 602 } 603 604 if (msym_bunch_index == BUNCH_SIZE) 605 { 606 new = (struct msym_bunch *) xmalloc (sizeof (struct msym_bunch)); 607 msym_bunch_index = 0; 608 new->next = msym_bunch; 609 msym_bunch = new; 610 } 611 msymbol = &msym_bunch->contents[msym_bunch_index]; 612 SYMBOL_INIT_LANGUAGE_SPECIFIC (msymbol, language_unknown); 613 SYMBOL_LANGUAGE (msymbol) = language_auto; 614 SYMBOL_SET_NAMES (msymbol, (char *)name, strlen (name), objfile); 615 616 SYMBOL_VALUE_ADDRESS (msymbol) = address; 617 SYMBOL_SECTION (msymbol) = section; 618 SYMBOL_BFD_SECTION (msymbol) = bfd_section; 619 620 MSYMBOL_TYPE (msymbol) = ms_type; 621 /* FIXME: This info, if it remains, needs its own field. */ 622 MSYMBOL_INFO (msymbol) = info; /* FIXME! */ 623 MSYMBOL_SIZE (msymbol) = 0; 624 625 /* The hash pointers must be cleared! If they're not, 626 add_minsym_to_hash_table will NOT add this msymbol to the hash table. */ 627 msymbol->hash_next = NULL; 628 msymbol->demangled_hash_next = NULL; 629 630 msym_bunch_index++; 631 msym_count++; 632 OBJSTAT (objfile, n_minsyms++); 633 return msymbol; 634} 635 636/* Compare two minimal symbols by address and return a signed result based 637 on unsigned comparisons, so that we sort into unsigned numeric order. 638 Within groups with the same address, sort by name. */ 639 640static int 641compare_minimal_symbols (const void *fn1p, const void *fn2p) 642{ 643 const struct minimal_symbol *fn1; 644 const struct minimal_symbol *fn2; 645 646 fn1 = (const struct minimal_symbol *) fn1p; 647 fn2 = (const struct minimal_symbol *) fn2p; 648 649 if (SYMBOL_VALUE_ADDRESS (fn1) < SYMBOL_VALUE_ADDRESS (fn2)) 650 { 651 return (-1); /* addr 1 is less than addr 2 */ 652 } 653 else if (SYMBOL_VALUE_ADDRESS (fn1) > SYMBOL_VALUE_ADDRESS (fn2)) 654 { 655 return (1); /* addr 1 is greater than addr 2 */ 656 } 657 else 658 /* addrs are equal: sort by name */ 659 { 660 char *name1 = SYMBOL_LINKAGE_NAME (fn1); 661 char *name2 = SYMBOL_LINKAGE_NAME (fn2); 662 663 if (name1 && name2) /* both have names */ 664 return strcmp (name1, name2); 665 else if (name2) 666 return 1; /* fn1 has no name, so it is "less" */ 667 else if (name1) /* fn2 has no name, so it is "less" */ 668 return -1; 669 else 670 return (0); /* neither has a name, so they're equal. */ 671 } 672} 673 674/* Discard the currently collected minimal symbols, if any. If we wish 675 to save them for later use, we must have already copied them somewhere 676 else before calling this function. 677 678 FIXME: We could allocate the minimal symbol bunches on their own 679 obstack and then simply blow the obstack away when we are done with 680 it. Is it worth the extra trouble though? */ 681 682static void 683do_discard_minimal_symbols_cleanup (void *arg) 684{ 685 struct msym_bunch *next; 686 687 while (msym_bunch != NULL) 688 { 689 next = msym_bunch->next; 690 xfree (msym_bunch); 691 msym_bunch = next; 692 } 693} 694 695struct cleanup * 696make_cleanup_discard_minimal_symbols (void) 697{ 698 return make_cleanup (do_discard_minimal_symbols_cleanup, 0); 699} 700 701 702 703/* Compact duplicate entries out of a minimal symbol table by walking 704 through the table and compacting out entries with duplicate addresses 705 and matching names. Return the number of entries remaining. 706 707 On entry, the table resides between msymbol[0] and msymbol[mcount]. 708 On exit, it resides between msymbol[0] and msymbol[result_count]. 709 710 When files contain multiple sources of symbol information, it is 711 possible for the minimal symbol table to contain many duplicate entries. 712 As an example, SVR4 systems use ELF formatted object files, which 713 usually contain at least two different types of symbol tables (a 714 standard ELF one and a smaller dynamic linking table), as well as 715 DWARF debugging information for files compiled with -g. 716 717 Without compacting, the minimal symbol table for gdb itself contains 718 over a 1000 duplicates, about a third of the total table size. Aside 719 from the potential trap of not noticing that two successive entries 720 identify the same location, this duplication impacts the time required 721 to linearly scan the table, which is done in a number of places. So we 722 just do one linear scan here and toss out the duplicates. 723 724 Note that we are not concerned here about recovering the space that 725 is potentially freed up, because the strings themselves are allocated 726 on the objfile_obstack, and will get automatically freed when the symbol 727 table is freed. The caller can free up the unused minimal symbols at 728 the end of the compacted region if their allocation strategy allows it. 729 730 Also note we only go up to the next to last entry within the loop 731 and then copy the last entry explicitly after the loop terminates. 732 733 Since the different sources of information for each symbol may 734 have different levels of "completeness", we may have duplicates 735 that have one entry with type "mst_unknown" and the other with a 736 known type. So if the one we are leaving alone has type mst_unknown, 737 overwrite its type with the type from the one we are compacting out. */ 738 739static int 740compact_minimal_symbols (struct minimal_symbol *msymbol, int mcount, 741 struct objfile *objfile) 742{ 743 struct minimal_symbol *copyfrom; 744 struct minimal_symbol *copyto; 745 746 if (mcount > 0) 747 { 748 copyfrom = copyto = msymbol; 749 while (copyfrom < msymbol + mcount - 1) 750 { 751 if (SYMBOL_VALUE_ADDRESS (copyfrom) 752 == SYMBOL_VALUE_ADDRESS ((copyfrom + 1)) 753 && strcmp (SYMBOL_LINKAGE_NAME (copyfrom), 754 SYMBOL_LINKAGE_NAME ((copyfrom + 1))) == 0) 755 { 756 if (MSYMBOL_TYPE ((copyfrom + 1)) == mst_unknown) 757 { 758 MSYMBOL_TYPE ((copyfrom + 1)) = MSYMBOL_TYPE (copyfrom); 759 } 760 copyfrom++; 761 } 762 else 763 *copyto++ = *copyfrom++; 764 } 765 *copyto++ = *copyfrom++; 766 mcount = copyto - msymbol; 767 } 768 return (mcount); 769} 770 771/* Build (or rebuild) the minimal symbol hash tables. This is necessary 772 after compacting or sorting the table since the entries move around 773 thus causing the internal minimal_symbol pointers to become jumbled. */ 774 775static void 776build_minimal_symbol_hash_tables (struct objfile *objfile) 777{ 778 int i; 779 struct minimal_symbol *msym; 780 781 /* Clear the hash tables. */ 782 for (i = 0; i < MINIMAL_SYMBOL_HASH_SIZE; i++) 783 { 784 objfile->msymbol_hash[i] = 0; 785 objfile->msymbol_demangled_hash[i] = 0; 786 } 787 788 /* Now, (re)insert the actual entries. */ 789 for (i = objfile->minimal_symbol_count, msym = objfile->msymbols; 790 i > 0; 791 i--, msym++) 792 { 793 msym->hash_next = 0; 794 add_minsym_to_hash_table (msym, objfile->msymbol_hash); 795 796 msym->demangled_hash_next = 0; 797 if (SYMBOL_DEMANGLED_NAME (msym) != NULL) 798 add_minsym_to_demangled_hash_table (msym, 799 objfile->msymbol_demangled_hash); 800 } 801} 802 803/* Add the minimal symbols in the existing bunches to the objfile's official 804 minimal symbol table. In most cases there is no minimal symbol table yet 805 for this objfile, and the existing bunches are used to create one. Once 806 in a while (for shared libraries for example), we add symbols (e.g. common 807 symbols) to an existing objfile. 808 809 Because of the way minimal symbols are collected, we generally have no way 810 of knowing what source language applies to any particular minimal symbol. 811 Specifically, we have no way of knowing if the minimal symbol comes from a 812 C++ compilation unit or not. So for the sake of supporting cached 813 demangled C++ names, we have no choice but to try and demangle each new one 814 that comes in. If the demangling succeeds, then we assume it is a C++ 815 symbol and set the symbol's language and demangled name fields 816 appropriately. Note that in order to avoid unnecessary demanglings, and 817 allocating obstack space that subsequently can't be freed for the demangled 818 names, we mark all newly added symbols with language_auto. After 819 compaction of the minimal symbols, we go back and scan the entire minimal 820 symbol table looking for these new symbols. For each new symbol we attempt 821 to demangle it, and if successful, record it as a language_cplus symbol 822 and cache the demangled form on the symbol obstack. Symbols which don't 823 demangle are marked as language_unknown symbols, which inhibits future 824 attempts to demangle them if we later add more minimal symbols. */ 825 826void 827install_minimal_symbols (struct objfile *objfile) 828{ 829 int bindex; 830 int mcount; 831 struct msym_bunch *bunch; 832 struct minimal_symbol *msymbols; 833 int alloc_count; 834 char leading_char; 835 836 if (msym_count > 0) 837 { 838 /* Allocate enough space in the obstack, into which we will gather the 839 bunches of new and existing minimal symbols, sort them, and then 840 compact out the duplicate entries. Once we have a final table, 841 we will give back the excess space. */ 842 843 alloc_count = msym_count + objfile->minimal_symbol_count + 1; 844 obstack_blank (&objfile->objfile_obstack, 845 alloc_count * sizeof (struct minimal_symbol)); 846 msymbols = (struct minimal_symbol *) 847 obstack_base (&objfile->objfile_obstack); 848 849 /* Copy in the existing minimal symbols, if there are any. */ 850 851 if (objfile->minimal_symbol_count) 852 memcpy ((char *) msymbols, (char *) objfile->msymbols, 853 objfile->minimal_symbol_count * sizeof (struct minimal_symbol)); 854 855 /* Walk through the list of minimal symbol bunches, adding each symbol 856 to the new contiguous array of symbols. Note that we start with the 857 current, possibly partially filled bunch (thus we use the current 858 msym_bunch_index for the first bunch we copy over), and thereafter 859 each bunch is full. */ 860 861 mcount = objfile->minimal_symbol_count; 862 leading_char = get_symbol_leading_char (objfile->obfd); 863 864 for (bunch = msym_bunch; bunch != NULL; bunch = bunch->next) 865 { 866 for (bindex = 0; bindex < msym_bunch_index; bindex++, mcount++) 867 { 868 msymbols[mcount] = bunch->contents[bindex]; 869 if (SYMBOL_LINKAGE_NAME (&msymbols[mcount])[0] == leading_char) 870 { 871 SYMBOL_LINKAGE_NAME (&msymbols[mcount])++; 872 } 873 } 874 msym_bunch_index = BUNCH_SIZE; 875 } 876 877 /* Sort the minimal symbols by address. */ 878 879 qsort (msymbols, mcount, sizeof (struct minimal_symbol), 880 compare_minimal_symbols); 881 882 /* Compact out any duplicates, and free up whatever space we are 883 no longer using. */ 884 885 mcount = compact_minimal_symbols (msymbols, mcount, objfile); 886 887 obstack_blank (&objfile->objfile_obstack, 888 (mcount + 1 - alloc_count) * sizeof (struct minimal_symbol)); 889 msymbols = (struct minimal_symbol *) 890 obstack_finish (&objfile->objfile_obstack); 891 892 /* We also terminate the minimal symbol table with a "null symbol", 893 which is *not* included in the size of the table. This makes it 894 easier to find the end of the table when we are handed a pointer 895 to some symbol in the middle of it. Zero out the fields in the 896 "null symbol" allocated at the end of the array. Note that the 897 symbol count does *not* include this null symbol, which is why it 898 is indexed by mcount and not mcount-1. */ 899 900 SYMBOL_LINKAGE_NAME (&msymbols[mcount]) = NULL; 901 SYMBOL_VALUE_ADDRESS (&msymbols[mcount]) = 0; 902 MSYMBOL_INFO (&msymbols[mcount]) = NULL; 903 MSYMBOL_SIZE (&msymbols[mcount]) = 0; 904 MSYMBOL_TYPE (&msymbols[mcount]) = mst_unknown; 905 SYMBOL_INIT_LANGUAGE_SPECIFIC (&msymbols[mcount], language_unknown); 906 907 /* Attach the minimal symbol table to the specified objfile. 908 The strings themselves are also located in the objfile_obstack 909 of this objfile. */ 910 911 objfile->minimal_symbol_count = mcount; 912 objfile->msymbols = msymbols; 913 914 /* Try to guess the appropriate C++ ABI by looking at the names 915 of the minimal symbols in the table. */ 916 { 917 int i; 918 919 for (i = 0; i < mcount; i++) 920 { 921 /* If a symbol's name starts with _Z and was successfully 922 demangled, then we can assume we've found a GNU v3 symbol. 923 For now we set the C++ ABI globally; if the user is 924 mixing ABIs then the user will need to "set cp-abi" 925 manually. */ 926 const char *name = SYMBOL_LINKAGE_NAME (&objfile->msymbols[i]); 927 if (name[0] == '_' && name[1] == 'Z' 928 && SYMBOL_DEMANGLED_NAME (&objfile->msymbols[i]) != NULL) 929 { 930 set_cp_abi_as_auto_default ("gnu-v3"); 931 break; 932 } 933 } 934 } 935 936 /* Now build the hash tables; we can't do this incrementally 937 at an earlier point since we weren't finished with the obstack 938 yet. (And if the msymbol obstack gets moved, all the internal 939 pointers to other msymbols need to be adjusted.) */ 940 build_minimal_symbol_hash_tables (objfile); 941 } 942} 943 944/* Sort all the minimal symbols in OBJFILE. */ 945 946void 947msymbols_sort (struct objfile *objfile) 948{ 949 qsort (objfile->msymbols, objfile->minimal_symbol_count, 950 sizeof (struct minimal_symbol), compare_minimal_symbols); 951 build_minimal_symbol_hash_tables (objfile); 952} 953 954/* Check if PC is in a shared library trampoline code stub. 955 Return minimal symbol for the trampoline entry or NULL if PC is not 956 in a trampoline code stub. */ 957 958struct minimal_symbol * 959lookup_solib_trampoline_symbol_by_pc (CORE_ADDR pc) 960{ 961 struct minimal_symbol *msymbol = lookup_minimal_symbol_by_pc (pc); 962 963 if (msymbol != NULL && MSYMBOL_TYPE (msymbol) == mst_solib_trampoline) 964 return msymbol; 965 return NULL; 966} 967 968/* If PC is in a shared library trampoline code stub, return the 969 address of the `real' function belonging to the stub. 970 Return 0 if PC is not in a trampoline code stub or if the real 971 function is not found in the minimal symbol table. 972 973 We may fail to find the right function if a function with the 974 same name is defined in more than one shared library, but this 975 is considered bad programming style. We could return 0 if we find 976 a duplicate function in case this matters someday. */ 977 978CORE_ADDR 979find_solib_trampoline_target (CORE_ADDR pc) 980{ 981 struct objfile *objfile; 982 struct minimal_symbol *msymbol; 983 struct minimal_symbol *tsymbol = lookup_solib_trampoline_symbol_by_pc (pc); 984 985 if (tsymbol != NULL) 986 { 987 ALL_MSYMBOLS (objfile, msymbol) 988 { 989 if (MSYMBOL_TYPE (msymbol) == mst_text 990 && strcmp (SYMBOL_LINKAGE_NAME (msymbol), 991 SYMBOL_LINKAGE_NAME (tsymbol)) == 0) 992 return SYMBOL_VALUE_ADDRESS (msymbol); 993 } 994 } 995 return 0; 996} 997