1 /* GDB routines for manipulating the minimal symbol tables. 2 Copyright (C) 1992-2013 Free Software Foundation, Inc. 3 Contributed by Cygnus Support, using pieces from other GDB modules. 4 5 This file is part of GDB. 6 7 This program is free software; you can redistribute it and/or modify 8 it under the terms of the GNU General Public License as published by 9 the Free Software Foundation; either version 3 of the License, or 10 (at your option) any later version. 11 12 This program is distributed in the hope that it will be useful, 13 but WITHOUT ANY WARRANTY; without even the implied warranty of 14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 15 GNU General Public License for more details. 16 17 You should have received a copy of the GNU General Public License 18 along with this program. If not, see <http://www.gnu.org/licenses/>. */ 19 20 21 /* This file contains support routines for creating, manipulating, and 22 destroying minimal symbol tables. 23 24 Minimal symbol tables are used to hold some very basic information about 25 all defined global symbols (text, data, bss, abs, etc). The only two 26 required pieces of information are the symbol's name and the address 27 associated with that symbol. 28 29 In many cases, even if a file was compiled with no special options for 30 debugging at all, as long as was not stripped it will contain sufficient 31 information to build useful minimal symbol tables using this structure. 32 33 Even when a file contains enough debugging information to build a full 34 symbol table, these minimal symbols are still useful for quickly mapping 35 between names and addresses, and vice versa. They are also sometimes used 36 to figure out what full symbol table entries need to be read in. */ 37 38 39 #include "defs.h" 40 #include <ctype.h> 41 #include "gdb_string.h" 42 #include "symtab.h" 43 #include "bfd.h" 44 #include "filenames.h" 45 #include "symfile.h" 46 #include "objfiles.h" 47 #include "demangle.h" 48 #include "value.h" 49 #include "cp-abi.h" 50 #include "target.h" 51 #include "cp-support.h" 52 #include "language.h" 53 #include "cli/cli-utils.h" 54 55 /* Accumulate the minimal symbols for each objfile in bunches of BUNCH_SIZE. 56 At the end, copy them all into one newly allocated location on an objfile's 57 symbol obstack. */ 58 59 #define BUNCH_SIZE 127 60 61 struct msym_bunch 62 { 63 struct msym_bunch *next; 64 struct minimal_symbol contents[BUNCH_SIZE]; 65 }; 66 67 /* Bunch currently being filled up. 68 The next field points to chain of filled bunches. */ 69 70 static struct msym_bunch *msym_bunch; 71 72 /* Number of slots filled in current bunch. */ 73 74 static int msym_bunch_index; 75 76 /* Total number of minimal symbols recorded so far for the objfile. */ 77 78 static int msym_count; 79 80 /* See minsyms.h. */ 81 82 unsigned int 83 msymbol_hash_iw (const char *string) 84 { 85 unsigned int hash = 0; 86 87 while (*string && *string != '(') 88 { 89 string = skip_spaces_const (string); 90 if (*string && *string != '(') 91 { 92 hash = SYMBOL_HASH_NEXT (hash, *string); 93 ++string; 94 } 95 } 96 return hash; 97 } 98 99 /* See minsyms.h. */ 100 101 unsigned int 102 msymbol_hash (const char *string) 103 { 104 unsigned int hash = 0; 105 106 for (; *string; ++string) 107 hash = SYMBOL_HASH_NEXT (hash, *string); 108 return hash; 109 } 110 111 /* Add the minimal symbol SYM to an objfile's minsym hash table, TABLE. */ 112 static void 113 add_minsym_to_hash_table (struct minimal_symbol *sym, 114 struct minimal_symbol **table) 115 { 116 if (sym->hash_next == NULL) 117 { 118 unsigned int hash 119 = msymbol_hash (SYMBOL_LINKAGE_NAME (sym)) % MINIMAL_SYMBOL_HASH_SIZE; 120 121 sym->hash_next = table[hash]; 122 table[hash] = sym; 123 } 124 } 125 126 /* Add the minimal symbol SYM to an objfile's minsym demangled hash table, 127 TABLE. */ 128 static void 129 add_minsym_to_demangled_hash_table (struct minimal_symbol *sym, 130 struct minimal_symbol **table) 131 { 132 if (sym->demangled_hash_next == NULL) 133 { 134 unsigned int hash = msymbol_hash_iw (SYMBOL_SEARCH_NAME (sym)) 135 % MINIMAL_SYMBOL_HASH_SIZE; 136 137 sym->demangled_hash_next = table[hash]; 138 table[hash] = sym; 139 } 140 } 141 142 /* See minsyms.h. */ 143 144 struct objfile * 145 msymbol_objfile (struct minimal_symbol *sym) 146 { 147 struct objfile *objf; 148 struct minimal_symbol *tsym; 149 150 unsigned int hash 151 = msymbol_hash (SYMBOL_LINKAGE_NAME (sym)) % MINIMAL_SYMBOL_HASH_SIZE; 152 153 for (objf = object_files; objf; objf = objf->next) 154 for (tsym = objf->msymbol_hash[hash]; tsym; tsym = tsym->hash_next) 155 if (tsym == sym) 156 return objf; 157 158 /* We should always be able to find the objfile ... */ 159 internal_error (__FILE__, __LINE__, _("failed internal consistency check")); 160 } 161 162 163 /* Look through all the current minimal symbol tables and find the 164 first minimal symbol that matches NAME. If OBJF is non-NULL, limit 165 the search to that objfile. If SFILE is non-NULL, the only file-scope 166 symbols considered will be from that source file (global symbols are 167 still preferred). Returns a pointer to the minimal symbol that 168 matches, or NULL if no match is found. 169 170 Note: One instance where there may be duplicate minimal symbols with 171 the same name is when the symbol tables for a shared library and the 172 symbol tables for an executable contain global symbols with the same 173 names (the dynamic linker deals with the duplication). 174 175 It's also possible to have minimal symbols with different mangled 176 names, but identical demangled names. For example, the GNU C++ v3 177 ABI requires the generation of two (or perhaps three) copies of 178 constructor functions --- "in-charge", "not-in-charge", and 179 "allocate" copies; destructors may be duplicated as well. 180 Obviously, there must be distinct mangled names for each of these, 181 but the demangled names are all the same: S::S or S::~S. */ 182 183 struct minimal_symbol * 184 lookup_minimal_symbol (const char *name, const char *sfile, 185 struct objfile *objf) 186 { 187 struct objfile *objfile; 188 struct minimal_symbol *msymbol; 189 struct minimal_symbol *found_symbol = NULL; 190 struct minimal_symbol *found_file_symbol = NULL; 191 struct minimal_symbol *trampoline_symbol = NULL; 192 193 unsigned int hash = msymbol_hash (name) % MINIMAL_SYMBOL_HASH_SIZE; 194 unsigned int dem_hash = msymbol_hash_iw (name) % MINIMAL_SYMBOL_HASH_SIZE; 195 196 int needtofreename = 0; 197 const char *modified_name; 198 199 if (sfile != NULL) 200 sfile = lbasename (sfile); 201 202 /* For C++, canonicalize the input name. */ 203 modified_name = name; 204 if (current_language->la_language == language_cplus) 205 { 206 char *cname = cp_canonicalize_string (name); 207 208 if (cname) 209 { 210 modified_name = cname; 211 needtofreename = 1; 212 } 213 } 214 215 for (objfile = object_files; 216 objfile != NULL && found_symbol == NULL; 217 objfile = objfile->next) 218 { 219 if (objf == NULL || objf == objfile 220 || objf == objfile->separate_debug_objfile_backlink) 221 { 222 /* Do two passes: the first over the ordinary hash table, 223 and the second over the demangled hash table. */ 224 int pass; 225 226 for (pass = 1; pass <= 2 && found_symbol == NULL; pass++) 227 { 228 /* Select hash list according to pass. */ 229 if (pass == 1) 230 msymbol = objfile->msymbol_hash[hash]; 231 else 232 msymbol = objfile->msymbol_demangled_hash[dem_hash]; 233 234 while (msymbol != NULL && found_symbol == NULL) 235 { 236 int match; 237 238 if (pass == 1) 239 { 240 int (*cmp) (const char *, const char *); 241 242 cmp = (case_sensitivity == case_sensitive_on 243 ? strcmp : strcasecmp); 244 match = cmp (SYMBOL_LINKAGE_NAME (msymbol), 245 modified_name) == 0; 246 } 247 else 248 { 249 /* The function respects CASE_SENSITIVITY. */ 250 match = SYMBOL_MATCHES_SEARCH_NAME (msymbol, 251 modified_name); 252 } 253 254 if (match) 255 { 256 switch (MSYMBOL_TYPE (msymbol)) 257 { 258 case mst_file_text: 259 case mst_file_data: 260 case mst_file_bss: 261 if (sfile == NULL 262 || filename_cmp (msymbol->filename, sfile) == 0) 263 found_file_symbol = msymbol; 264 break; 265 266 case mst_solib_trampoline: 267 268 /* If a trampoline symbol is found, we prefer to 269 keep looking for the *real* symbol. If the 270 actual symbol is not found, then we'll use the 271 trampoline entry. */ 272 if (trampoline_symbol == NULL) 273 trampoline_symbol = msymbol; 274 break; 275 276 case mst_unknown: 277 default: 278 found_symbol = msymbol; 279 break; 280 } 281 } 282 283 /* Find the next symbol on the hash chain. */ 284 if (pass == 1) 285 msymbol = msymbol->hash_next; 286 else 287 msymbol = msymbol->demangled_hash_next; 288 } 289 } 290 } 291 } 292 293 if (needtofreename) 294 xfree ((void *) modified_name); 295 296 /* External symbols are best. */ 297 if (found_symbol) 298 return found_symbol; 299 300 /* File-local symbols are next best. */ 301 if (found_file_symbol) 302 return found_file_symbol; 303 304 /* Symbols for shared library trampolines are next best. */ 305 if (trampoline_symbol) 306 return trampoline_symbol; 307 308 return NULL; 309 } 310 311 /* See minsyms.h. */ 312 313 void 314 iterate_over_minimal_symbols (struct objfile *objf, const char *name, 315 void (*callback) (struct minimal_symbol *, 316 void *), 317 void *user_data) 318 { 319 unsigned int hash; 320 struct minimal_symbol *iter; 321 int (*cmp) (const char *, const char *); 322 323 /* The first pass is over the ordinary hash table. */ 324 hash = msymbol_hash (name) % MINIMAL_SYMBOL_HASH_SIZE; 325 iter = objf->msymbol_hash[hash]; 326 cmp = (case_sensitivity == case_sensitive_on ? strcmp : strcasecmp); 327 while (iter) 328 { 329 if (cmp (SYMBOL_LINKAGE_NAME (iter), name) == 0) 330 (*callback) (iter, user_data); 331 iter = iter->hash_next; 332 } 333 334 /* The second pass is over the demangled table. */ 335 hash = msymbol_hash_iw (name) % MINIMAL_SYMBOL_HASH_SIZE; 336 iter = objf->msymbol_demangled_hash[hash]; 337 while (iter) 338 { 339 if (SYMBOL_MATCHES_SEARCH_NAME (iter, name)) 340 (*callback) (iter, user_data); 341 iter = iter->demangled_hash_next; 342 } 343 } 344 345 /* See minsyms.h. */ 346 347 struct minimal_symbol * 348 lookup_minimal_symbol_text (const char *name, struct objfile *objf) 349 { 350 struct objfile *objfile; 351 struct minimal_symbol *msymbol; 352 struct minimal_symbol *found_symbol = NULL; 353 struct minimal_symbol *found_file_symbol = NULL; 354 355 unsigned int hash = msymbol_hash (name) % MINIMAL_SYMBOL_HASH_SIZE; 356 357 for (objfile = object_files; 358 objfile != NULL && found_symbol == NULL; 359 objfile = objfile->next) 360 { 361 if (objf == NULL || objf == objfile 362 || objf == objfile->separate_debug_objfile_backlink) 363 { 364 for (msymbol = objfile->msymbol_hash[hash]; 365 msymbol != NULL && found_symbol == NULL; 366 msymbol = msymbol->hash_next) 367 { 368 if (strcmp (SYMBOL_LINKAGE_NAME (msymbol), name) == 0 && 369 (MSYMBOL_TYPE (msymbol) == mst_text 370 || MSYMBOL_TYPE (msymbol) == mst_text_gnu_ifunc 371 || MSYMBOL_TYPE (msymbol) == mst_file_text)) 372 { 373 switch (MSYMBOL_TYPE (msymbol)) 374 { 375 case mst_file_text: 376 found_file_symbol = msymbol; 377 break; 378 default: 379 found_symbol = msymbol; 380 break; 381 } 382 } 383 } 384 } 385 } 386 /* External symbols are best. */ 387 if (found_symbol) 388 return found_symbol; 389 390 /* File-local symbols are next best. */ 391 if (found_file_symbol) 392 return found_file_symbol; 393 394 return NULL; 395 } 396 397 /* See minsyms.h. */ 398 399 struct minimal_symbol * 400 lookup_minimal_symbol_by_pc_name (CORE_ADDR pc, const char *name, 401 struct objfile *objf) 402 { 403 struct objfile *objfile; 404 struct minimal_symbol *msymbol; 405 406 unsigned int hash = msymbol_hash (name) % MINIMAL_SYMBOL_HASH_SIZE; 407 408 for (objfile = object_files; 409 objfile != NULL; 410 objfile = objfile->next) 411 { 412 if (objf == NULL || objf == objfile 413 || objf == objfile->separate_debug_objfile_backlink) 414 { 415 for (msymbol = objfile->msymbol_hash[hash]; 416 msymbol != NULL; 417 msymbol = msymbol->hash_next) 418 { 419 if (SYMBOL_VALUE_ADDRESS (msymbol) == pc 420 && strcmp (SYMBOL_LINKAGE_NAME (msymbol), name) == 0) 421 return msymbol; 422 } 423 } 424 } 425 426 return NULL; 427 } 428 429 /* See minsyms.h. */ 430 431 struct minimal_symbol * 432 lookup_minimal_symbol_solib_trampoline (const char *name, 433 struct objfile *objf) 434 { 435 struct objfile *objfile; 436 struct minimal_symbol *msymbol; 437 struct minimal_symbol *found_symbol = NULL; 438 439 unsigned int hash = msymbol_hash (name) % MINIMAL_SYMBOL_HASH_SIZE; 440 441 for (objfile = object_files; 442 objfile != NULL && found_symbol == NULL; 443 objfile = objfile->next) 444 { 445 if (objf == NULL || objf == objfile 446 || objf == objfile->separate_debug_objfile_backlink) 447 { 448 for (msymbol = objfile->msymbol_hash[hash]; 449 msymbol != NULL && found_symbol == NULL; 450 msymbol = msymbol->hash_next) 451 { 452 if (strcmp (SYMBOL_LINKAGE_NAME (msymbol), name) == 0 && 453 MSYMBOL_TYPE (msymbol) == mst_solib_trampoline) 454 return msymbol; 455 } 456 } 457 } 458 459 return NULL; 460 } 461 462 /* Search through the minimal symbol table for each objfile and find 463 the symbol whose address is the largest address that is still less 464 than or equal to PC, and matches SECTION (which is not NULL). 465 Returns a pointer to the minimal symbol if such a symbol is found, 466 or NULL if PC is not in a suitable range. 467 Note that we need to look through ALL the minimal symbol tables 468 before deciding on the symbol that comes closest to the specified PC. 469 This is because objfiles can overlap, for example objfile A has .text 470 at 0x100 and .data at 0x40000 and objfile B has .text at 0x234 and 471 .data at 0x40048. 472 473 If WANT_TRAMPOLINE is set, prefer mst_solib_trampoline symbols when 474 there are text and trampoline symbols at the same address. 475 Otherwise prefer mst_text symbols. */ 476 477 static struct minimal_symbol * 478 lookup_minimal_symbol_by_pc_section_1 (CORE_ADDR pc, 479 struct obj_section *section, 480 int want_trampoline) 481 { 482 int lo; 483 int hi; 484 int new; 485 struct objfile *objfile; 486 struct minimal_symbol *msymbol; 487 struct minimal_symbol *best_symbol = NULL; 488 enum minimal_symbol_type want_type, other_type; 489 490 want_type = want_trampoline ? mst_solib_trampoline : mst_text; 491 other_type = want_trampoline ? mst_text : mst_solib_trampoline; 492 493 /* We can not require the symbol found to be in section, because 494 e.g. IRIX 6.5 mdebug relies on this code returning an absolute 495 symbol - but find_pc_section won't return an absolute section and 496 hence the code below would skip over absolute symbols. We can 497 still take advantage of the call to find_pc_section, though - the 498 object file still must match. In case we have separate debug 499 files, search both the file and its separate debug file. There's 500 no telling which one will have the minimal symbols. */ 501 502 gdb_assert (section != NULL); 503 504 for (objfile = section->objfile; 505 objfile != NULL; 506 objfile = objfile_separate_debug_iterate (section->objfile, objfile)) 507 { 508 /* If this objfile has a minimal symbol table, go search it using 509 a binary search. Note that a minimal symbol table always consists 510 of at least two symbols, a "real" symbol and the terminating 511 "null symbol". If there are no real symbols, then there is no 512 minimal symbol table at all. */ 513 514 if (objfile->minimal_symbol_count > 0) 515 { 516 int best_zero_sized = -1; 517 518 msymbol = objfile->msymbols; 519 lo = 0; 520 hi = objfile->minimal_symbol_count - 1; 521 522 /* This code assumes that the minimal symbols are sorted by 523 ascending address values. If the pc value is greater than or 524 equal to the first symbol's address, then some symbol in this 525 minimal symbol table is a suitable candidate for being the 526 "best" symbol. This includes the last real symbol, for cases 527 where the pc value is larger than any address in this vector. 528 529 By iterating until the address associated with the current 530 hi index (the endpoint of the test interval) is less than 531 or equal to the desired pc value, we accomplish two things: 532 (1) the case where the pc value is larger than any minimal 533 symbol address is trivially solved, (2) the address associated 534 with the hi index is always the one we want when the interation 535 terminates. In essence, we are iterating the test interval 536 down until the pc value is pushed out of it from the high end. 537 538 Warning: this code is trickier than it would appear at first. */ 539 540 /* Should also require that pc is <= end of objfile. FIXME! */ 541 if (pc >= SYMBOL_VALUE_ADDRESS (&msymbol[lo])) 542 { 543 while (SYMBOL_VALUE_ADDRESS (&msymbol[hi]) > pc) 544 { 545 /* pc is still strictly less than highest address. */ 546 /* Note "new" will always be >= lo. */ 547 new = (lo + hi) / 2; 548 if ((SYMBOL_VALUE_ADDRESS (&msymbol[new]) >= pc) || 549 (lo == new)) 550 { 551 hi = new; 552 } 553 else 554 { 555 lo = new; 556 } 557 } 558 559 /* If we have multiple symbols at the same address, we want 560 hi to point to the last one. That way we can find the 561 right symbol if it has an index greater than hi. */ 562 while (hi < objfile->minimal_symbol_count - 1 563 && (SYMBOL_VALUE_ADDRESS (&msymbol[hi]) 564 == SYMBOL_VALUE_ADDRESS (&msymbol[hi + 1]))) 565 hi++; 566 567 /* Skip various undesirable symbols. */ 568 while (hi >= 0) 569 { 570 /* Skip any absolute symbols. This is apparently 571 what adb and dbx do, and is needed for the CM-5. 572 There are two known possible problems: (1) on 573 ELF, apparently end, edata, etc. are absolute. 574 Not sure ignoring them here is a big deal, but if 575 we want to use them, the fix would go in 576 elfread.c. (2) I think shared library entry 577 points on the NeXT are absolute. If we want 578 special handling for this it probably should be 579 triggered by a special mst_abs_or_lib or some 580 such. */ 581 582 if (MSYMBOL_TYPE (&msymbol[hi]) == mst_abs) 583 { 584 hi--; 585 continue; 586 } 587 588 /* If SECTION was specified, skip any symbol from 589 wrong section. */ 590 if (section 591 /* Some types of debug info, such as COFF, 592 don't fill the bfd_section member, so don't 593 throw away symbols on those platforms. */ 594 && SYMBOL_OBJ_SECTION (&msymbol[hi]) != NULL 595 && (!matching_obj_sections 596 (SYMBOL_OBJ_SECTION (&msymbol[hi]), section))) 597 { 598 hi--; 599 continue; 600 } 601 602 /* If we are looking for a trampoline and this is a 603 text symbol, or the other way around, check the 604 preceding symbol too. If they are otherwise 605 identical prefer that one. */ 606 if (hi > 0 607 && MSYMBOL_TYPE (&msymbol[hi]) == other_type 608 && MSYMBOL_TYPE (&msymbol[hi - 1]) == want_type 609 && (MSYMBOL_SIZE (&msymbol[hi]) 610 == MSYMBOL_SIZE (&msymbol[hi - 1])) 611 && (SYMBOL_VALUE_ADDRESS (&msymbol[hi]) 612 == SYMBOL_VALUE_ADDRESS (&msymbol[hi - 1])) 613 && (SYMBOL_OBJ_SECTION (&msymbol[hi]) 614 == SYMBOL_OBJ_SECTION (&msymbol[hi - 1]))) 615 { 616 hi--; 617 continue; 618 } 619 620 /* If the minimal symbol has a zero size, save it 621 but keep scanning backwards looking for one with 622 a non-zero size. A zero size may mean that the 623 symbol isn't an object or function (e.g. a 624 label), or it may just mean that the size was not 625 specified. */ 626 if (MSYMBOL_SIZE (&msymbol[hi]) == 0 627 && best_zero_sized == -1) 628 { 629 best_zero_sized = hi; 630 hi--; 631 continue; 632 } 633 634 /* If we are past the end of the current symbol, try 635 the previous symbol if it has a larger overlapping 636 size. This happens on i686-pc-linux-gnu with glibc; 637 the nocancel variants of system calls are inside 638 the cancellable variants, but both have sizes. */ 639 if (hi > 0 640 && MSYMBOL_SIZE (&msymbol[hi]) != 0 641 && pc >= (SYMBOL_VALUE_ADDRESS (&msymbol[hi]) 642 + MSYMBOL_SIZE (&msymbol[hi])) 643 && pc < (SYMBOL_VALUE_ADDRESS (&msymbol[hi - 1]) 644 + MSYMBOL_SIZE (&msymbol[hi - 1]))) 645 { 646 hi--; 647 continue; 648 } 649 650 /* Otherwise, this symbol must be as good as we're going 651 to get. */ 652 break; 653 } 654 655 /* If HI has a zero size, and best_zero_sized is set, 656 then we had two or more zero-sized symbols; prefer 657 the first one we found (which may have a higher 658 address). Also, if we ran off the end, be sure 659 to back up. */ 660 if (best_zero_sized != -1 661 && (hi < 0 || MSYMBOL_SIZE (&msymbol[hi]) == 0)) 662 hi = best_zero_sized; 663 664 /* If the minimal symbol has a non-zero size, and this 665 PC appears to be outside the symbol's contents, then 666 refuse to use this symbol. If we found a zero-sized 667 symbol with an address greater than this symbol's, 668 use that instead. We assume that if symbols have 669 specified sizes, they do not overlap. */ 670 671 if (hi >= 0 672 && MSYMBOL_SIZE (&msymbol[hi]) != 0 673 && pc >= (SYMBOL_VALUE_ADDRESS (&msymbol[hi]) 674 + MSYMBOL_SIZE (&msymbol[hi]))) 675 { 676 if (best_zero_sized != -1) 677 hi = best_zero_sized; 678 else 679 /* Go on to the next object file. */ 680 continue; 681 } 682 683 /* The minimal symbol indexed by hi now is the best one in this 684 objfile's minimal symbol table. See if it is the best one 685 overall. */ 686 687 if (hi >= 0 688 && ((best_symbol == NULL) || 689 (SYMBOL_VALUE_ADDRESS (best_symbol) < 690 SYMBOL_VALUE_ADDRESS (&msymbol[hi])))) 691 { 692 best_symbol = &msymbol[hi]; 693 } 694 } 695 } 696 } 697 return (best_symbol); 698 } 699 700 struct minimal_symbol * 701 lookup_minimal_symbol_by_pc_section (CORE_ADDR pc, struct obj_section *section) 702 { 703 if (section == NULL) 704 { 705 /* NOTE: cagney/2004-01-27: This was using find_pc_mapped_section to 706 force the section but that (well unless you're doing overlay 707 debugging) always returns NULL making the call somewhat useless. */ 708 section = find_pc_section (pc); 709 if (section == NULL) 710 return NULL; 711 } 712 return lookup_minimal_symbol_by_pc_section_1 (pc, section, 0); 713 } 714 715 /* See minsyms.h. */ 716 717 struct minimal_symbol * 718 lookup_minimal_symbol_by_pc (CORE_ADDR pc) 719 { 720 return lookup_minimal_symbol_by_pc_section (pc, NULL); 721 } 722 723 /* Return non-zero iff PC is in an STT_GNU_IFUNC function resolver. */ 724 725 int 726 in_gnu_ifunc_stub (CORE_ADDR pc) 727 { 728 struct minimal_symbol *msymbol = lookup_minimal_symbol_by_pc (pc); 729 730 return msymbol && MSYMBOL_TYPE (msymbol) == mst_text_gnu_ifunc; 731 } 732 733 /* See elf_gnu_ifunc_resolve_addr for its real implementation. */ 734 735 static CORE_ADDR 736 stub_gnu_ifunc_resolve_addr (struct gdbarch *gdbarch, CORE_ADDR pc) 737 { 738 error (_("GDB cannot resolve STT_GNU_IFUNC symbol at address %s without " 739 "the ELF support compiled in."), 740 paddress (gdbarch, pc)); 741 } 742 743 /* See elf_gnu_ifunc_resolve_name for its real implementation. */ 744 745 static int 746 stub_gnu_ifunc_resolve_name (const char *function_name, 747 CORE_ADDR *function_address_p) 748 { 749 error (_("GDB cannot resolve STT_GNU_IFUNC symbol \"%s\" without " 750 "the ELF support compiled in."), 751 function_name); 752 } 753 754 /* See elf_gnu_ifunc_resolver_stop for its real implementation. */ 755 756 static void 757 stub_gnu_ifunc_resolver_stop (struct breakpoint *b) 758 { 759 internal_error (__FILE__, __LINE__, 760 _("elf_gnu_ifunc_resolver_stop cannot be reached.")); 761 } 762 763 /* See elf_gnu_ifunc_resolver_return_stop for its real implementation. */ 764 765 static void 766 stub_gnu_ifunc_resolver_return_stop (struct breakpoint *b) 767 { 768 internal_error (__FILE__, __LINE__, 769 _("elf_gnu_ifunc_resolver_return_stop cannot be reached.")); 770 } 771 772 /* See elf_gnu_ifunc_fns for its real implementation. */ 773 774 static const struct gnu_ifunc_fns stub_gnu_ifunc_fns = 775 { 776 stub_gnu_ifunc_resolve_addr, 777 stub_gnu_ifunc_resolve_name, 778 stub_gnu_ifunc_resolver_stop, 779 stub_gnu_ifunc_resolver_return_stop, 780 }; 781 782 /* A placeholder for &elf_gnu_ifunc_fns. */ 783 784 const struct gnu_ifunc_fns *gnu_ifunc_fns_p = &stub_gnu_ifunc_fns; 785 786 /* See minsyms.h. */ 787 788 struct minimal_symbol * 789 lookup_minimal_symbol_and_objfile (const char *name, 790 struct objfile **objfile_p) 791 { 792 struct objfile *objfile; 793 unsigned int hash = msymbol_hash (name) % MINIMAL_SYMBOL_HASH_SIZE; 794 795 ALL_OBJFILES (objfile) 796 { 797 struct minimal_symbol *msym; 798 799 for (msym = objfile->msymbol_hash[hash]; 800 msym != NULL; 801 msym = msym->hash_next) 802 { 803 if (strcmp (SYMBOL_LINKAGE_NAME (msym), name) == 0) 804 { 805 *objfile_p = objfile; 806 return msym; 807 } 808 } 809 } 810 811 return 0; 812 } 813 814 815 /* Return leading symbol character for a BFD. If BFD is NULL, 816 return the leading symbol character from the main objfile. */ 817 818 static int get_symbol_leading_char (bfd *); 819 820 static int 821 get_symbol_leading_char (bfd *abfd) 822 { 823 if (abfd != NULL) 824 return bfd_get_symbol_leading_char (abfd); 825 if (symfile_objfile != NULL && symfile_objfile->obfd != NULL) 826 return bfd_get_symbol_leading_char (symfile_objfile->obfd); 827 return 0; 828 } 829 830 /* See minsyms.h. */ 831 832 void 833 init_minimal_symbol_collection (void) 834 { 835 msym_count = 0; 836 msym_bunch = NULL; 837 /* Note that presetting msym_bunch_index to BUNCH_SIZE causes the 838 first call to save a minimal symbol to allocate the memory for 839 the first bunch. */ 840 msym_bunch_index = BUNCH_SIZE; 841 } 842 843 /* See minsyms.h. */ 844 845 void 846 prim_record_minimal_symbol (const char *name, CORE_ADDR address, 847 enum minimal_symbol_type ms_type, 848 struct objfile *objfile) 849 { 850 int section; 851 852 switch (ms_type) 853 { 854 case mst_text: 855 case mst_text_gnu_ifunc: 856 case mst_file_text: 857 case mst_solib_trampoline: 858 section = SECT_OFF_TEXT (objfile); 859 break; 860 case mst_data: 861 case mst_file_data: 862 section = SECT_OFF_DATA (objfile); 863 break; 864 case mst_bss: 865 case mst_file_bss: 866 section = SECT_OFF_BSS (objfile); 867 break; 868 default: 869 section = -1; 870 } 871 872 prim_record_minimal_symbol_and_info (name, address, ms_type, 873 section, NULL, objfile); 874 } 875 876 /* See minsyms.h. */ 877 878 struct minimal_symbol * 879 prim_record_minimal_symbol_full (const char *name, int name_len, int copy_name, 880 CORE_ADDR address, 881 enum minimal_symbol_type ms_type, 882 int section, 883 asection *bfd_section, 884 struct objfile *objfile) 885 { 886 struct obj_section *obj_section; 887 struct msym_bunch *new; 888 struct minimal_symbol *msymbol; 889 890 /* Don't put gcc_compiled, __gnu_compiled_cplus, and friends into 891 the minimal symbols, because if there is also another symbol 892 at the same address (e.g. the first function of the file), 893 lookup_minimal_symbol_by_pc would have no way of getting the 894 right one. */ 895 if (ms_type == mst_file_text && name[0] == 'g' 896 && (strcmp (name, GCC_COMPILED_FLAG_SYMBOL) == 0 897 || strcmp (name, GCC2_COMPILED_FLAG_SYMBOL) == 0)) 898 return (NULL); 899 900 /* It's safe to strip the leading char here once, since the name 901 is also stored stripped in the minimal symbol table. */ 902 if (name[0] == get_symbol_leading_char (objfile->obfd)) 903 { 904 ++name; 905 --name_len; 906 } 907 908 if (ms_type == mst_file_text && strncmp (name, "__gnu_compiled", 14) == 0) 909 return (NULL); 910 911 if (msym_bunch_index == BUNCH_SIZE) 912 { 913 new = XCALLOC (1, struct msym_bunch); 914 msym_bunch_index = 0; 915 new->next = msym_bunch; 916 msym_bunch = new; 917 } 918 msymbol = &msym_bunch->contents[msym_bunch_index]; 919 SYMBOL_SET_LANGUAGE (msymbol, language_auto); 920 SYMBOL_SET_NAMES (msymbol, name, name_len, copy_name, objfile); 921 922 SYMBOL_VALUE_ADDRESS (msymbol) = address; 923 SYMBOL_SECTION (msymbol) = section; 924 SYMBOL_OBJ_SECTION (msymbol) = NULL; 925 926 /* Find obj_section corresponding to bfd_section. */ 927 if (bfd_section) 928 ALL_OBJFILE_OSECTIONS (objfile, obj_section) 929 { 930 if (obj_section->the_bfd_section == bfd_section) 931 { 932 SYMBOL_OBJ_SECTION (msymbol) = obj_section; 933 break; 934 } 935 } 936 937 MSYMBOL_TYPE (msymbol) = ms_type; 938 MSYMBOL_TARGET_FLAG_1 (msymbol) = 0; 939 MSYMBOL_TARGET_FLAG_2 (msymbol) = 0; 940 /* Do not use the SET_MSYMBOL_SIZE macro to initialize the size, 941 as it would also set the has_size flag. */ 942 msymbol->size = 0; 943 944 /* The hash pointers must be cleared! If they're not, 945 add_minsym_to_hash_table will NOT add this msymbol to the hash table. */ 946 msymbol->hash_next = NULL; 947 msymbol->demangled_hash_next = NULL; 948 949 msym_bunch_index++; 950 msym_count++; 951 OBJSTAT (objfile, n_minsyms++); 952 return msymbol; 953 } 954 955 /* See minsyms.h. */ 956 957 struct minimal_symbol * 958 prim_record_minimal_symbol_and_info (const char *name, CORE_ADDR address, 959 enum minimal_symbol_type ms_type, 960 int section, 961 asection *bfd_section, 962 struct objfile *objfile) 963 { 964 return prim_record_minimal_symbol_full (name, strlen (name), 1, 965 address, ms_type, section, 966 bfd_section, objfile); 967 } 968 969 /* Compare two minimal symbols by address and return a signed result based 970 on unsigned comparisons, so that we sort into unsigned numeric order. 971 Within groups with the same address, sort by name. */ 972 973 static int 974 compare_minimal_symbols (const void *fn1p, const void *fn2p) 975 { 976 const struct minimal_symbol *fn1; 977 const struct minimal_symbol *fn2; 978 979 fn1 = (const struct minimal_symbol *) fn1p; 980 fn2 = (const struct minimal_symbol *) fn2p; 981 982 if (SYMBOL_VALUE_ADDRESS (fn1) < SYMBOL_VALUE_ADDRESS (fn2)) 983 { 984 return (-1); /* addr 1 is less than addr 2. */ 985 } 986 else if (SYMBOL_VALUE_ADDRESS (fn1) > SYMBOL_VALUE_ADDRESS (fn2)) 987 { 988 return (1); /* addr 1 is greater than addr 2. */ 989 } 990 else 991 /* addrs are equal: sort by name */ 992 { 993 const char *name1 = SYMBOL_LINKAGE_NAME (fn1); 994 const char *name2 = SYMBOL_LINKAGE_NAME (fn2); 995 996 if (name1 && name2) /* both have names */ 997 return strcmp (name1, name2); 998 else if (name2) 999 return 1; /* fn1 has no name, so it is "less". */ 1000 else if (name1) /* fn2 has no name, so it is "less". */ 1001 return -1; 1002 else 1003 return (0); /* Neither has a name, so they're equal. */ 1004 } 1005 } 1006 1007 /* Discard the currently collected minimal symbols, if any. If we wish 1008 to save them for later use, we must have already copied them somewhere 1009 else before calling this function. 1010 1011 FIXME: We could allocate the minimal symbol bunches on their own 1012 obstack and then simply blow the obstack away when we are done with 1013 it. Is it worth the extra trouble though? */ 1014 1015 static void 1016 do_discard_minimal_symbols_cleanup (void *arg) 1017 { 1018 struct msym_bunch *next; 1019 1020 while (msym_bunch != NULL) 1021 { 1022 next = msym_bunch->next; 1023 xfree (msym_bunch); 1024 msym_bunch = next; 1025 } 1026 } 1027 1028 /* See minsyms.h. */ 1029 1030 struct cleanup * 1031 make_cleanup_discard_minimal_symbols (void) 1032 { 1033 return make_cleanup (do_discard_minimal_symbols_cleanup, 0); 1034 } 1035 1036 1037 1038 /* Compact duplicate entries out of a minimal symbol table by walking 1039 through the table and compacting out entries with duplicate addresses 1040 and matching names. Return the number of entries remaining. 1041 1042 On entry, the table resides between msymbol[0] and msymbol[mcount]. 1043 On exit, it resides between msymbol[0] and msymbol[result_count]. 1044 1045 When files contain multiple sources of symbol information, it is 1046 possible for the minimal symbol table to contain many duplicate entries. 1047 As an example, SVR4 systems use ELF formatted object files, which 1048 usually contain at least two different types of symbol tables (a 1049 standard ELF one and a smaller dynamic linking table), as well as 1050 DWARF debugging information for files compiled with -g. 1051 1052 Without compacting, the minimal symbol table for gdb itself contains 1053 over a 1000 duplicates, about a third of the total table size. Aside 1054 from the potential trap of not noticing that two successive entries 1055 identify the same location, this duplication impacts the time required 1056 to linearly scan the table, which is done in a number of places. So we 1057 just do one linear scan here and toss out the duplicates. 1058 1059 Note that we are not concerned here about recovering the space that 1060 is potentially freed up, because the strings themselves are allocated 1061 on the objfile_obstack, and will get automatically freed when the symbol 1062 table is freed. The caller can free up the unused minimal symbols at 1063 the end of the compacted region if their allocation strategy allows it. 1064 1065 Also note we only go up to the next to last entry within the loop 1066 and then copy the last entry explicitly after the loop terminates. 1067 1068 Since the different sources of information for each symbol may 1069 have different levels of "completeness", we may have duplicates 1070 that have one entry with type "mst_unknown" and the other with a 1071 known type. So if the one we are leaving alone has type mst_unknown, 1072 overwrite its type with the type from the one we are compacting out. */ 1073 1074 static int 1075 compact_minimal_symbols (struct minimal_symbol *msymbol, int mcount, 1076 struct objfile *objfile) 1077 { 1078 struct minimal_symbol *copyfrom; 1079 struct minimal_symbol *copyto; 1080 1081 if (mcount > 0) 1082 { 1083 copyfrom = copyto = msymbol; 1084 while (copyfrom < msymbol + mcount - 1) 1085 { 1086 if (SYMBOL_VALUE_ADDRESS (copyfrom) 1087 == SYMBOL_VALUE_ADDRESS ((copyfrom + 1)) 1088 && strcmp (SYMBOL_LINKAGE_NAME (copyfrom), 1089 SYMBOL_LINKAGE_NAME ((copyfrom + 1))) == 0) 1090 { 1091 if (MSYMBOL_TYPE ((copyfrom + 1)) == mst_unknown) 1092 { 1093 MSYMBOL_TYPE ((copyfrom + 1)) = MSYMBOL_TYPE (copyfrom); 1094 } 1095 copyfrom++; 1096 } 1097 else 1098 *copyto++ = *copyfrom++; 1099 } 1100 *copyto++ = *copyfrom++; 1101 mcount = copyto - msymbol; 1102 } 1103 return (mcount); 1104 } 1105 1106 /* Build (or rebuild) the minimal symbol hash tables. This is necessary 1107 after compacting or sorting the table since the entries move around 1108 thus causing the internal minimal_symbol pointers to become jumbled. */ 1109 1110 static void 1111 build_minimal_symbol_hash_tables (struct objfile *objfile) 1112 { 1113 int i; 1114 struct minimal_symbol *msym; 1115 1116 /* Clear the hash tables. */ 1117 for (i = 0; i < MINIMAL_SYMBOL_HASH_SIZE; i++) 1118 { 1119 objfile->msymbol_hash[i] = 0; 1120 objfile->msymbol_demangled_hash[i] = 0; 1121 } 1122 1123 /* Now, (re)insert the actual entries. */ 1124 for (i = objfile->minimal_symbol_count, msym = objfile->msymbols; 1125 i > 0; 1126 i--, msym++) 1127 { 1128 msym->hash_next = 0; 1129 add_minsym_to_hash_table (msym, objfile->msymbol_hash); 1130 1131 msym->demangled_hash_next = 0; 1132 if (SYMBOL_SEARCH_NAME (msym) != SYMBOL_LINKAGE_NAME (msym)) 1133 add_minsym_to_demangled_hash_table (msym, 1134 objfile->msymbol_demangled_hash); 1135 } 1136 } 1137 1138 /* Add the minimal symbols in the existing bunches to the objfile's official 1139 minimal symbol table. In most cases there is no minimal symbol table yet 1140 for this objfile, and the existing bunches are used to create one. Once 1141 in a while (for shared libraries for example), we add symbols (e.g. common 1142 symbols) to an existing objfile. 1143 1144 Because of the way minimal symbols are collected, we generally have no way 1145 of knowing what source language applies to any particular minimal symbol. 1146 Specifically, we have no way of knowing if the minimal symbol comes from a 1147 C++ compilation unit or not. So for the sake of supporting cached 1148 demangled C++ names, we have no choice but to try and demangle each new one 1149 that comes in. If the demangling succeeds, then we assume it is a C++ 1150 symbol and set the symbol's language and demangled name fields 1151 appropriately. Note that in order to avoid unnecessary demanglings, and 1152 allocating obstack space that subsequently can't be freed for the demangled 1153 names, we mark all newly added symbols with language_auto. After 1154 compaction of the minimal symbols, we go back and scan the entire minimal 1155 symbol table looking for these new symbols. For each new symbol we attempt 1156 to demangle it, and if successful, record it as a language_cplus symbol 1157 and cache the demangled form on the symbol obstack. Symbols which don't 1158 demangle are marked as language_unknown symbols, which inhibits future 1159 attempts to demangle them if we later add more minimal symbols. */ 1160 1161 void 1162 install_minimal_symbols (struct objfile *objfile) 1163 { 1164 int bindex; 1165 int mcount; 1166 struct msym_bunch *bunch; 1167 struct minimal_symbol *msymbols; 1168 int alloc_count; 1169 1170 if (msym_count > 0) 1171 { 1172 if (symtab_create_debug) 1173 { 1174 fprintf_unfiltered (gdb_stdlog, 1175 "Installing %d minimal symbols of objfile %s.\n", 1176 msym_count, objfile->name); 1177 } 1178 1179 /* Allocate enough space in the obstack, into which we will gather the 1180 bunches of new and existing minimal symbols, sort them, and then 1181 compact out the duplicate entries. Once we have a final table, 1182 we will give back the excess space. */ 1183 1184 alloc_count = msym_count + objfile->minimal_symbol_count + 1; 1185 obstack_blank (&objfile->objfile_obstack, 1186 alloc_count * sizeof (struct minimal_symbol)); 1187 msymbols = (struct minimal_symbol *) 1188 obstack_base (&objfile->objfile_obstack); 1189 1190 /* Copy in the existing minimal symbols, if there are any. */ 1191 1192 if (objfile->minimal_symbol_count) 1193 memcpy ((char *) msymbols, (char *) objfile->msymbols, 1194 objfile->minimal_symbol_count * sizeof (struct minimal_symbol)); 1195 1196 /* Walk through the list of minimal symbol bunches, adding each symbol 1197 to the new contiguous array of symbols. Note that we start with the 1198 current, possibly partially filled bunch (thus we use the current 1199 msym_bunch_index for the first bunch we copy over), and thereafter 1200 each bunch is full. */ 1201 1202 mcount = objfile->minimal_symbol_count; 1203 1204 for (bunch = msym_bunch; bunch != NULL; bunch = bunch->next) 1205 { 1206 for (bindex = 0; bindex < msym_bunch_index; bindex++, mcount++) 1207 msymbols[mcount] = bunch->contents[bindex]; 1208 msym_bunch_index = BUNCH_SIZE; 1209 } 1210 1211 /* Sort the minimal symbols by address. */ 1212 1213 qsort (msymbols, mcount, sizeof (struct minimal_symbol), 1214 compare_minimal_symbols); 1215 1216 /* Compact out any duplicates, and free up whatever space we are 1217 no longer using. */ 1218 1219 mcount = compact_minimal_symbols (msymbols, mcount, objfile); 1220 1221 obstack_blank (&objfile->objfile_obstack, 1222 (mcount + 1 - alloc_count) * sizeof (struct minimal_symbol)); 1223 msymbols = (struct minimal_symbol *) 1224 obstack_finish (&objfile->objfile_obstack); 1225 1226 /* We also terminate the minimal symbol table with a "null symbol", 1227 which is *not* included in the size of the table. This makes it 1228 easier to find the end of the table when we are handed a pointer 1229 to some symbol in the middle of it. Zero out the fields in the 1230 "null symbol" allocated at the end of the array. Note that the 1231 symbol count does *not* include this null symbol, which is why it 1232 is indexed by mcount and not mcount-1. */ 1233 1234 memset (&msymbols[mcount], 0, sizeof (struct minimal_symbol)); 1235 1236 /* Attach the minimal symbol table to the specified objfile. 1237 The strings themselves are also located in the objfile_obstack 1238 of this objfile. */ 1239 1240 objfile->minimal_symbol_count = mcount; 1241 objfile->msymbols = msymbols; 1242 1243 /* Now build the hash tables; we can't do this incrementally 1244 at an earlier point since we weren't finished with the obstack 1245 yet. (And if the msymbol obstack gets moved, all the internal 1246 pointers to other msymbols need to be adjusted.) */ 1247 build_minimal_symbol_hash_tables (objfile); 1248 } 1249 } 1250 1251 /* See minsyms.h. */ 1252 1253 void 1254 terminate_minimal_symbol_table (struct objfile *objfile) 1255 { 1256 if (! objfile->msymbols) 1257 objfile->msymbols = ((struct minimal_symbol *) 1258 obstack_alloc (&objfile->objfile_obstack, 1259 sizeof (objfile->msymbols[0]))); 1260 1261 { 1262 struct minimal_symbol *m 1263 = &objfile->msymbols[objfile->minimal_symbol_count]; 1264 1265 memset (m, 0, sizeof (*m)); 1266 /* Don't rely on these enumeration values being 0's. */ 1267 MSYMBOL_TYPE (m) = mst_unknown; 1268 SYMBOL_SET_LANGUAGE (m, language_unknown); 1269 } 1270 } 1271 1272 /* Sort all the minimal symbols in OBJFILE. */ 1273 1274 void 1275 msymbols_sort (struct objfile *objfile) 1276 { 1277 qsort (objfile->msymbols, objfile->minimal_symbol_count, 1278 sizeof (struct minimal_symbol), compare_minimal_symbols); 1279 build_minimal_symbol_hash_tables (objfile); 1280 } 1281 1282 /* Check if PC is in a shared library trampoline code stub. 1283 Return minimal symbol for the trampoline entry or NULL if PC is not 1284 in a trampoline code stub. */ 1285 1286 static struct minimal_symbol * 1287 lookup_solib_trampoline_symbol_by_pc (CORE_ADDR pc) 1288 { 1289 struct obj_section *section = find_pc_section (pc); 1290 struct minimal_symbol *msymbol; 1291 1292 if (section == NULL) 1293 return NULL; 1294 msymbol = lookup_minimal_symbol_by_pc_section_1 (pc, section, 1); 1295 1296 if (msymbol != NULL && MSYMBOL_TYPE (msymbol) == mst_solib_trampoline) 1297 return msymbol; 1298 return NULL; 1299 } 1300 1301 /* If PC is in a shared library trampoline code stub, return the 1302 address of the `real' function belonging to the stub. 1303 Return 0 if PC is not in a trampoline code stub or if the real 1304 function is not found in the minimal symbol table. 1305 1306 We may fail to find the right function if a function with the 1307 same name is defined in more than one shared library, but this 1308 is considered bad programming style. We could return 0 if we find 1309 a duplicate function in case this matters someday. */ 1310 1311 CORE_ADDR 1312 find_solib_trampoline_target (struct frame_info *frame, CORE_ADDR pc) 1313 { 1314 struct objfile *objfile; 1315 struct minimal_symbol *msymbol; 1316 struct minimal_symbol *tsymbol = lookup_solib_trampoline_symbol_by_pc (pc); 1317 1318 if (tsymbol != NULL) 1319 { 1320 ALL_MSYMBOLS (objfile, msymbol) 1321 { 1322 if ((MSYMBOL_TYPE (msymbol) == mst_text 1323 || MSYMBOL_TYPE (msymbol) == mst_text_gnu_ifunc) 1324 && strcmp (SYMBOL_LINKAGE_NAME (msymbol), 1325 SYMBOL_LINKAGE_NAME (tsymbol)) == 0) 1326 return SYMBOL_VALUE_ADDRESS (msymbol); 1327 1328 /* Also handle minimal symbols pointing to function descriptors. */ 1329 if (MSYMBOL_TYPE (msymbol) == mst_data 1330 && strcmp (SYMBOL_LINKAGE_NAME (msymbol), 1331 SYMBOL_LINKAGE_NAME (tsymbol)) == 0) 1332 { 1333 CORE_ADDR func; 1334 1335 func = gdbarch_convert_from_func_ptr_addr 1336 (get_objfile_arch (objfile), 1337 SYMBOL_VALUE_ADDRESS (msymbol), 1338 ¤t_target); 1339 1340 /* Ignore data symbols that are not function descriptors. */ 1341 if (func != SYMBOL_VALUE_ADDRESS (msymbol)) 1342 return func; 1343 } 1344 } 1345 } 1346 return 0; 1347 } 1348