1 /* GDB routines for manipulating the minimal symbol tables.
2 Copyright (C) 1992-2019 Free Software Foundation, Inc.
3 Contributed by Cygnus Support, using pieces from other GDB modules.
5 This file is part of GDB.
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.
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.
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/>. */
21 /* This file contains support routines for creating, manipulating, and
22 destroying minimal symbol tables.
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.
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.
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. */
43 #include "filenames.h"
50 #include "cp-support.h"
52 #include "cli/cli-utils.h"
53 #include "common/symbol.h"
55 #include "safe-ctype.h"
60 msymbol_is_function (struct objfile *objfile, minimal_symbol *minsym,
61 CORE_ADDR *func_address_p)
63 CORE_ADDR msym_addr = MSYMBOL_VALUE_ADDRESS (objfile, minsym);
67 case mst_slot_got_plt:
73 case mst_data_gnu_ifunc:
75 struct gdbarch *gdbarch = get_objfile_arch (objfile);
77 = gdbarch_convert_from_func_ptr_addr (gdbarch, msym_addr,
78 current_top_target ());
81 if (func_address_p != NULL)
88 if (func_address_p != NULL)
89 *func_address_p = msym_addr;
94 /* Accumulate the minimal symbols for each objfile in bunches of BUNCH_SIZE.
95 At the end, copy them all into one newly allocated location on an objfile's
96 per-BFD storage obstack. */
98 #define BUNCH_SIZE 127
102 struct msym_bunch *next;
103 struct minimal_symbol contents[BUNCH_SIZE];
109 msymbol_hash_iw (const char *string)
111 unsigned int hash = 0;
113 while (*string && *string != '(')
115 string = skip_spaces (string);
116 if (*string && *string != '(')
118 hash = SYMBOL_HASH_NEXT (hash, *string);
128 msymbol_hash (const char *string)
130 unsigned int hash = 0;
132 for (; *string; ++string)
133 hash = SYMBOL_HASH_NEXT (hash, *string);
137 /* Add the minimal symbol SYM to an objfile's minsym hash table, TABLE. */
139 add_minsym_to_hash_table (struct minimal_symbol *sym,
140 struct minimal_symbol **table)
142 if (sym->hash_next == NULL)
145 = msymbol_hash (MSYMBOL_LINKAGE_NAME (sym)) % MINIMAL_SYMBOL_HASH_SIZE;
147 sym->hash_next = table[hash];
152 /* Add the minimal symbol SYM to an objfile's minsym demangled hash table,
155 add_minsym_to_demangled_hash_table (struct minimal_symbol *sym,
156 struct objfile *objfile)
158 if (sym->demangled_hash_next == NULL)
160 unsigned int hash = search_name_hash (MSYMBOL_LANGUAGE (sym),
161 MSYMBOL_SEARCH_NAME (sym));
163 objfile->per_bfd->demangled_hash_languages.set (MSYMBOL_LANGUAGE (sym));
165 struct minimal_symbol **table
166 = objfile->per_bfd->msymbol_demangled_hash;
167 unsigned int hash_index = hash % MINIMAL_SYMBOL_HASH_SIZE;
168 sym->demangled_hash_next = table[hash_index];
169 table[hash_index] = sym;
173 /* Worker object for lookup_minimal_symbol. Stores temporary results
174 while walking the symbol tables. */
176 struct found_minimal_symbols
178 /* External symbols are best. */
179 bound_minimal_symbol external_symbol {};
181 /* File-local symbols are next best. */
182 bound_minimal_symbol file_symbol {};
184 /* Symbols for shared library trampolines are next best. */
185 bound_minimal_symbol trampoline_symbol {};
187 /* Called when a symbol name matches. Check if the minsym is a
188 better type than what we had already found, and record it in one
189 of the members fields if so. Returns true if we collected the
190 real symbol, in which case we can stop searching. */
191 bool maybe_collect (const char *sfile, objfile *objf,
192 minimal_symbol *msymbol);
195 /* See declaration above. */
198 found_minimal_symbols::maybe_collect (const char *sfile,
199 struct objfile *objfile,
200 minimal_symbol *msymbol)
202 switch (MSYMBOL_TYPE (msymbol))
208 || filename_cmp (msymbol->filename, sfile) == 0)
210 file_symbol.minsym = msymbol;
211 file_symbol.objfile = objfile;
215 case mst_solib_trampoline:
217 /* If a trampoline symbol is found, we prefer to keep
218 looking for the *real* symbol. If the actual symbol
219 is not found, then we'll use the trampoline
221 if (trampoline_symbol.minsym == NULL)
223 trampoline_symbol.minsym = msymbol;
224 trampoline_symbol.objfile = objfile;
230 external_symbol.minsym = msymbol;
231 external_symbol.objfile = objfile;
232 /* We have the real symbol. No use looking further. */
240 /* Walk the mangled name hash table, and pass each symbol whose name
241 matches LOOKUP_NAME according to NAMECMP to FOUND. */
244 lookup_minimal_symbol_mangled (const char *lookup_name,
246 struct objfile *objfile,
247 struct minimal_symbol **table,
249 int (*namecmp) (const char *, const char *),
250 found_minimal_symbols &found)
252 for (minimal_symbol *msymbol = table[hash];
254 msymbol = msymbol->hash_next)
256 const char *symbol_name = MSYMBOL_LINKAGE_NAME (msymbol);
258 if (namecmp (symbol_name, lookup_name) == 0
259 && found.maybe_collect (sfile, objfile, msymbol))
264 /* Walk the demangled name hash table, and pass each symbol whose name
265 matches LOOKUP_NAME according to MATCHER to FOUND. */
268 lookup_minimal_symbol_demangled (const lookup_name_info &lookup_name,
270 struct objfile *objfile,
271 struct minimal_symbol **table,
273 symbol_name_matcher_ftype *matcher,
274 found_minimal_symbols &found)
276 for (minimal_symbol *msymbol = table[hash];
278 msymbol = msymbol->demangled_hash_next)
280 const char *symbol_name = MSYMBOL_SEARCH_NAME (msymbol);
282 if (matcher (symbol_name, lookup_name, NULL)
283 && found.maybe_collect (sfile, objfile, msymbol))
288 /* Look through all the current minimal symbol tables and find the
289 first minimal symbol that matches NAME. If OBJF is non-NULL, limit
290 the search to that objfile. If SFILE is non-NULL, the only file-scope
291 symbols considered will be from that source file (global symbols are
292 still preferred). Returns a pointer to the minimal symbol that
293 matches, or NULL if no match is found.
295 Note: One instance where there may be duplicate minimal symbols with
296 the same name is when the symbol tables for a shared library and the
297 symbol tables for an executable contain global symbols with the same
298 names (the dynamic linker deals with the duplication).
300 It's also possible to have minimal symbols with different mangled
301 names, but identical demangled names. For example, the GNU C++ v3
302 ABI requires the generation of two (or perhaps three) copies of
303 constructor functions --- "in-charge", "not-in-charge", and
304 "allocate" copies; destructors may be duplicated as well.
305 Obviously, there must be distinct mangled names for each of these,
306 but the demangled names are all the same: S::S or S::~S. */
308 struct bound_minimal_symbol
309 lookup_minimal_symbol (const char *name, const char *sfile,
310 struct objfile *objf)
312 struct objfile *objfile;
313 found_minimal_symbols found;
315 unsigned int mangled_hash = msymbol_hash (name) % MINIMAL_SYMBOL_HASH_SIZE;
318 = (case_sensitivity == case_sensitive_on
323 sfile = lbasename (sfile);
325 lookup_name_info lookup_name (name, symbol_name_match_type::FULL);
327 for (objfile = object_files;
328 objfile != NULL && found.external_symbol.minsym == NULL;
329 objfile = objfile->next)
331 if (objf == NULL || objf == objfile
332 || objf == objfile->separate_debug_objfile_backlink)
334 if (symbol_lookup_debug)
336 fprintf_unfiltered (gdb_stdlog,
337 "lookup_minimal_symbol (%s, %s, %s)\n",
338 name, sfile != NULL ? sfile : "NULL",
339 objfile_debug_name (objfile));
342 /* Do two passes: the first over the ordinary hash table,
343 and the second over the demangled hash table. */
344 lookup_minimal_symbol_mangled (name, sfile, objfile,
345 objfile->per_bfd->msymbol_hash,
346 mangled_hash, mangled_cmp, found);
348 /* If not found, try the demangled hash table. */
349 if (found.external_symbol.minsym == NULL)
351 /* Once for each language in the demangled hash names
352 table (usually just zero or one languages). */
353 for (unsigned iter = 0; iter < nr_languages; ++iter)
355 if (!objfile->per_bfd->demangled_hash_languages.test (iter))
357 enum language lang = (enum language) iter;
360 = (lookup_name.search_name_hash (lang)
361 % MINIMAL_SYMBOL_HASH_SIZE);
363 symbol_name_matcher_ftype *match
364 = get_symbol_name_matcher (language_def (lang),
366 struct minimal_symbol **msymbol_demangled_hash
367 = objfile->per_bfd->msymbol_demangled_hash;
369 lookup_minimal_symbol_demangled (lookup_name, sfile, objfile,
370 msymbol_demangled_hash,
373 if (found.external_symbol.minsym != NULL)
380 /* External symbols are best. */
381 if (found.external_symbol.minsym != NULL)
383 if (symbol_lookup_debug)
385 minimal_symbol *minsym = found.external_symbol.minsym;
387 fprintf_unfiltered (gdb_stdlog,
388 "lookup_minimal_symbol (...) = %s (external)\n",
389 host_address_to_string (minsym));
391 return found.external_symbol;
394 /* File-local symbols are next best. */
395 if (found.file_symbol.minsym != NULL)
397 if (symbol_lookup_debug)
399 minimal_symbol *minsym = found.file_symbol.minsym;
401 fprintf_unfiltered (gdb_stdlog,
402 "lookup_minimal_symbol (...) = %s (file-local)\n",
403 host_address_to_string (minsym));
405 return found.file_symbol;
408 /* Symbols for shared library trampolines are next best. */
409 if (found.trampoline_symbol.minsym != NULL)
411 if (symbol_lookup_debug)
413 minimal_symbol *minsym = found.trampoline_symbol.minsym;
415 fprintf_unfiltered (gdb_stdlog,
416 "lookup_minimal_symbol (...) = %s (trampoline)\n",
417 host_address_to_string (minsym));
420 return found.trampoline_symbol;
424 if (symbol_lookup_debug)
425 fprintf_unfiltered (gdb_stdlog, "lookup_minimal_symbol (...) = NULL\n");
431 struct bound_minimal_symbol
432 lookup_bound_minimal_symbol (const char *name)
434 return lookup_minimal_symbol (name, NULL, NULL);
437 /* See common/symbol.h. */
440 find_minimal_symbol_address (const char *name, CORE_ADDR *addr,
441 struct objfile *objfile)
443 struct bound_minimal_symbol sym
444 = lookup_minimal_symbol (name, NULL, objfile);
446 if (sym.minsym != NULL)
447 *addr = BMSYMBOL_VALUE_ADDRESS (sym);
449 return sym.minsym == NULL;
452 /* Get the lookup name form best suitable for linkage name
456 linkage_name_str (const lookup_name_info &lookup_name)
458 /* Unlike most languages (including C++), Ada uses the
459 encoded/linkage name as the search name recorded in symbols. So
460 if debugging in Ada mode, prefer the Ada-encoded name. This also
461 makes Ada's verbatim match syntax ("<...>") work, because
462 "lookup_name.name()" includes the "<>"s, while
463 "lookup_name.ada().lookup_name()" is the encoded name with "<>"s
465 if (current_language->la_language == language_ada)
466 return lookup_name.ada ().lookup_name ().c_str ();
468 return lookup_name.name ().c_str ();
474 iterate_over_minimal_symbols
475 (struct objfile *objf, const lookup_name_info &lookup_name,
476 gdb::function_view<bool (struct minimal_symbol *)> callback)
478 /* The first pass is over the ordinary hash table. */
480 const char *name = linkage_name_str (lookup_name);
481 unsigned int hash = msymbol_hash (name) % MINIMAL_SYMBOL_HASH_SIZE;
483 = (case_sensitivity == case_sensitive_on
487 for (minimal_symbol *iter = objf->per_bfd->msymbol_hash[hash];
489 iter = iter->hash_next)
491 if (mangled_cmp (MSYMBOL_LINKAGE_NAME (iter), name) == 0)
497 /* The second pass is over the demangled table. Once for each
498 language in the demangled hash names table (usually just zero or
500 for (unsigned liter = 0; liter < nr_languages; ++liter)
502 if (!objf->per_bfd->demangled_hash_languages.test (liter))
505 enum language lang = (enum language) liter;
506 const language_defn *lang_def = language_def (lang);
507 symbol_name_matcher_ftype *name_match
508 = get_symbol_name_matcher (lang_def, lookup_name);
511 = lookup_name.search_name_hash (lang) % MINIMAL_SYMBOL_HASH_SIZE;
512 for (minimal_symbol *iter = objf->per_bfd->msymbol_demangled_hash[hash];
514 iter = iter->demangled_hash_next)
515 if (name_match (MSYMBOL_SEARCH_NAME (iter), lookup_name, NULL))
523 struct bound_minimal_symbol
524 lookup_minimal_symbol_text (const char *name, struct objfile *objf)
526 struct objfile *objfile;
527 struct minimal_symbol *msymbol;
528 struct bound_minimal_symbol found_symbol = { NULL, NULL };
529 struct bound_minimal_symbol found_file_symbol = { NULL, NULL };
531 unsigned int hash = msymbol_hash (name) % MINIMAL_SYMBOL_HASH_SIZE;
533 for (objfile = object_files;
534 objfile != NULL && found_symbol.minsym == NULL;
535 objfile = objfile->next)
537 if (objf == NULL || objf == objfile
538 || objf == objfile->separate_debug_objfile_backlink)
540 for (msymbol = objfile->per_bfd->msymbol_hash[hash];
541 msymbol != NULL && found_symbol.minsym == NULL;
542 msymbol = msymbol->hash_next)
544 if (strcmp (MSYMBOL_LINKAGE_NAME (msymbol), name) == 0 &&
545 (MSYMBOL_TYPE (msymbol) == mst_text
546 || MSYMBOL_TYPE (msymbol) == mst_text_gnu_ifunc
547 || MSYMBOL_TYPE (msymbol) == mst_file_text))
549 switch (MSYMBOL_TYPE (msymbol))
552 found_file_symbol.minsym = msymbol;
553 found_file_symbol.objfile = objfile;
556 found_symbol.minsym = msymbol;
557 found_symbol.objfile = objfile;
564 /* External symbols are best. */
565 if (found_symbol.minsym)
568 /* File-local symbols are next best. */
569 return found_file_symbol;
574 struct minimal_symbol *
575 lookup_minimal_symbol_by_pc_name (CORE_ADDR pc, const char *name,
576 struct objfile *objf)
578 struct objfile *objfile;
579 struct minimal_symbol *msymbol;
581 unsigned int hash = msymbol_hash (name) % MINIMAL_SYMBOL_HASH_SIZE;
583 for (objfile = object_files;
585 objfile = objfile->next)
587 if (objf == NULL || objf == objfile
588 || objf == objfile->separate_debug_objfile_backlink)
590 for (msymbol = objfile->per_bfd->msymbol_hash[hash];
592 msymbol = msymbol->hash_next)
594 if (MSYMBOL_VALUE_ADDRESS (objfile, msymbol) == pc
595 && strcmp (MSYMBOL_LINKAGE_NAME (msymbol), name) == 0)
606 struct bound_minimal_symbol
607 lookup_minimal_symbol_solib_trampoline (const char *name,
608 struct objfile *objf)
610 struct objfile *objfile;
611 struct minimal_symbol *msymbol;
612 struct bound_minimal_symbol found_symbol = { NULL, NULL };
614 unsigned int hash = msymbol_hash (name) % MINIMAL_SYMBOL_HASH_SIZE;
616 for (objfile = object_files;
618 objfile = objfile->next)
620 if (objf == NULL || objf == objfile
621 || objf == objfile->separate_debug_objfile_backlink)
623 for (msymbol = objfile->per_bfd->msymbol_hash[hash];
625 msymbol = msymbol->hash_next)
627 if (strcmp (MSYMBOL_LINKAGE_NAME (msymbol), name) == 0 &&
628 MSYMBOL_TYPE (msymbol) == mst_solib_trampoline)
630 found_symbol.objfile = objfile;
631 found_symbol.minsym = msymbol;
641 /* A helper function that makes *PC section-relative. This searches
642 the sections of OBJFILE and if *PC is in a section, it subtracts
643 the section offset and returns true. Otherwise it returns
647 frob_address (struct objfile *objfile, CORE_ADDR *pc)
649 struct obj_section *iter;
651 ALL_OBJFILE_OSECTIONS (objfile, iter)
653 if (*pc >= obj_section_addr (iter) && *pc < obj_section_endaddr (iter))
655 *pc -= obj_section_offset (iter);
663 /* Helper for lookup_minimal_symbol_by_pc_section. Convert a
664 lookup_msym_prefer to a minimal_symbol_type. */
666 static minimal_symbol_type
667 msym_prefer_to_msym_type (lookup_msym_prefer prefer)
671 case lookup_msym_prefer::TEXT:
673 case lookup_msym_prefer::TRAMPOLINE:
674 return mst_solib_trampoline;
675 case lookup_msym_prefer::GNU_IFUNC:
676 return mst_text_gnu_ifunc;
679 /* Assert here instead of in a default switch case above so that
680 -Wswitch warns if a new enumerator is added. */
681 gdb_assert_not_reached ("unhandled lookup_msym_prefer");
684 /* Search through the minimal symbol table for each objfile and find
685 the symbol whose address is the largest address that is still less
686 than or equal to PC, and matches SECTION (which is not NULL).
687 Returns a pointer to the minimal symbol if such a symbol is found,
688 or NULL if PC is not in a suitable range.
689 Note that we need to look through ALL the minimal symbol tables
690 before deciding on the symbol that comes closest to the specified PC.
691 This is because objfiles can overlap, for example objfile A has .text
692 at 0x100 and .data at 0x40000 and objfile B has .text at 0x234 and
695 If WANT_TRAMPOLINE is set, prefer mst_solib_trampoline symbols when
696 there are text and trampoline symbols at the same address.
697 Otherwise prefer mst_text symbols. */
700 lookup_minimal_symbol_by_pc_section (CORE_ADDR pc_in, struct obj_section *section,
701 lookup_msym_prefer prefer)
706 struct objfile *objfile;
707 struct minimal_symbol *msymbol;
708 struct minimal_symbol *best_symbol = NULL;
709 struct objfile *best_objfile = NULL;
710 struct bound_minimal_symbol result;
714 section = find_pc_section (pc_in);
719 minimal_symbol_type want_type = msym_prefer_to_msym_type (prefer);
721 /* We can not require the symbol found to be in section, because
722 e.g. IRIX 6.5 mdebug relies on this code returning an absolute
723 symbol - but find_pc_section won't return an absolute section and
724 hence the code below would skip over absolute symbols. We can
725 still take advantage of the call to find_pc_section, though - the
726 object file still must match. In case we have separate debug
727 files, search both the file and its separate debug file. There's
728 no telling which one will have the minimal symbols. */
730 gdb_assert (section != NULL);
732 for (objfile = section->objfile;
734 objfile = objfile_separate_debug_iterate (section->objfile, objfile))
736 CORE_ADDR pc = pc_in;
738 /* If this objfile has a minimal symbol table, go search it using
739 a binary search. Note that a minimal symbol table always consists
740 of at least two symbols, a "real" symbol and the terminating
741 "null symbol". If there are no real symbols, then there is no
742 minimal symbol table at all. */
744 if (objfile->per_bfd->minimal_symbol_count > 0)
746 int best_zero_sized = -1;
748 msymbol = objfile->per_bfd->msymbols;
750 hi = objfile->per_bfd->minimal_symbol_count - 1;
752 /* This code assumes that the minimal symbols are sorted by
753 ascending address values. If the pc value is greater than or
754 equal to the first symbol's address, then some symbol in this
755 minimal symbol table is a suitable candidate for being the
756 "best" symbol. This includes the last real symbol, for cases
757 where the pc value is larger than any address in this vector.
759 By iterating until the address associated with the current
760 hi index (the endpoint of the test interval) is less than
761 or equal to the desired pc value, we accomplish two things:
762 (1) the case where the pc value is larger than any minimal
763 symbol address is trivially solved, (2) the address associated
764 with the hi index is always the one we want when the interation
765 terminates. In essence, we are iterating the test interval
766 down until the pc value is pushed out of it from the high end.
768 Warning: this code is trickier than it would appear at first. */
770 if (frob_address (objfile, &pc)
771 && pc >= MSYMBOL_VALUE_RAW_ADDRESS (&msymbol[lo]))
773 while (MSYMBOL_VALUE_RAW_ADDRESS (&msymbol[hi]) > pc)
775 /* pc is still strictly less than highest address. */
776 /* Note "new" will always be >= lo. */
777 newobj = (lo + hi) / 2;
778 if ((MSYMBOL_VALUE_RAW_ADDRESS (&msymbol[newobj]) >= pc)
789 /* If we have multiple symbols at the same address, we want
790 hi to point to the last one. That way we can find the
791 right symbol if it has an index greater than hi. */
792 while (hi < objfile->per_bfd->minimal_symbol_count - 1
793 && (MSYMBOL_VALUE_RAW_ADDRESS (&msymbol[hi])
794 == MSYMBOL_VALUE_RAW_ADDRESS (&msymbol[hi + 1])))
797 /* Skip various undesirable symbols. */
800 /* Skip any absolute symbols. This is apparently
801 what adb and dbx do, and is needed for the CM-5.
802 There are two known possible problems: (1) on
803 ELF, apparently end, edata, etc. are absolute.
804 Not sure ignoring them here is a big deal, but if
805 we want to use them, the fix would go in
806 elfread.c. (2) I think shared library entry
807 points on the NeXT are absolute. If we want
808 special handling for this it probably should be
809 triggered by a special mst_abs_or_lib or some
812 if (MSYMBOL_TYPE (&msymbol[hi]) == mst_abs)
818 /* If SECTION was specified, skip any symbol from
821 /* Some types of debug info, such as COFF,
822 don't fill the bfd_section member, so don't
823 throw away symbols on those platforms. */
824 && MSYMBOL_OBJ_SECTION (objfile, &msymbol[hi]) != NULL
825 && (!matching_obj_sections
826 (MSYMBOL_OBJ_SECTION (objfile, &msymbol[hi]),
833 /* If we are looking for a trampoline and this is a
834 text symbol, or the other way around, check the
835 preceding symbol too. If they are otherwise
836 identical prefer that one. */
838 && MSYMBOL_TYPE (&msymbol[hi]) != want_type
839 && MSYMBOL_TYPE (&msymbol[hi - 1]) == want_type
840 && (MSYMBOL_SIZE (&msymbol[hi])
841 == MSYMBOL_SIZE (&msymbol[hi - 1]))
842 && (MSYMBOL_VALUE_RAW_ADDRESS (&msymbol[hi])
843 == MSYMBOL_VALUE_RAW_ADDRESS (&msymbol[hi - 1]))
844 && (MSYMBOL_OBJ_SECTION (objfile, &msymbol[hi])
845 == MSYMBOL_OBJ_SECTION (objfile, &msymbol[hi - 1])))
851 /* If the minimal symbol has a zero size, save it
852 but keep scanning backwards looking for one with
853 a non-zero size. A zero size may mean that the
854 symbol isn't an object or function (e.g. a
855 label), or it may just mean that the size was not
857 if (MSYMBOL_SIZE (&msymbol[hi]) == 0)
859 if (best_zero_sized == -1)
860 best_zero_sized = hi;
865 /* If we are past the end of the current symbol, try
866 the previous symbol if it has a larger overlapping
867 size. This happens on i686-pc-linux-gnu with glibc;
868 the nocancel variants of system calls are inside
869 the cancellable variants, but both have sizes. */
871 && MSYMBOL_SIZE (&msymbol[hi]) != 0
872 && pc >= (MSYMBOL_VALUE_RAW_ADDRESS (&msymbol[hi])
873 + MSYMBOL_SIZE (&msymbol[hi]))
874 && pc < (MSYMBOL_VALUE_RAW_ADDRESS (&msymbol[hi - 1])
875 + MSYMBOL_SIZE (&msymbol[hi - 1])))
881 /* Otherwise, this symbol must be as good as we're going
886 /* If HI has a zero size, and best_zero_sized is set,
887 then we had two or more zero-sized symbols; prefer
888 the first one we found (which may have a higher
889 address). Also, if we ran off the end, be sure
891 if (best_zero_sized != -1
892 && (hi < 0 || MSYMBOL_SIZE (&msymbol[hi]) == 0))
893 hi = best_zero_sized;
895 /* If the minimal symbol has a non-zero size, and this
896 PC appears to be outside the symbol's contents, then
897 refuse to use this symbol. If we found a zero-sized
898 symbol with an address greater than this symbol's,
899 use that instead. We assume that if symbols have
900 specified sizes, they do not overlap. */
903 && MSYMBOL_SIZE (&msymbol[hi]) != 0
904 && pc >= (MSYMBOL_VALUE_RAW_ADDRESS (&msymbol[hi])
905 + MSYMBOL_SIZE (&msymbol[hi])))
907 if (best_zero_sized != -1)
908 hi = best_zero_sized;
910 /* Go on to the next object file. */
914 /* The minimal symbol indexed by hi now is the best one in this
915 objfile's minimal symbol table. See if it is the best one
919 && ((best_symbol == NULL) ||
920 (MSYMBOL_VALUE_RAW_ADDRESS (best_symbol) <
921 MSYMBOL_VALUE_RAW_ADDRESS (&msymbol[hi]))))
923 best_symbol = &msymbol[hi];
924 best_objfile = objfile;
930 result.minsym = best_symbol;
931 result.objfile = best_objfile;
937 struct bound_minimal_symbol
938 lookup_minimal_symbol_by_pc (CORE_ADDR pc)
940 return lookup_minimal_symbol_by_pc_section (pc, NULL);
943 /* Return non-zero iff PC is in an STT_GNU_IFUNC function resolver. */
946 in_gnu_ifunc_stub (CORE_ADDR pc)
948 bound_minimal_symbol msymbol
949 = lookup_minimal_symbol_by_pc_section (pc, NULL,
950 lookup_msym_prefer::GNU_IFUNC);
951 return msymbol.minsym && MSYMBOL_TYPE (msymbol.minsym) == mst_text_gnu_ifunc;
954 /* See elf_gnu_ifunc_resolve_addr for its real implementation. */
957 stub_gnu_ifunc_resolve_addr (struct gdbarch *gdbarch, CORE_ADDR pc)
959 error (_("GDB cannot resolve STT_GNU_IFUNC symbol at address %s without "
960 "the ELF support compiled in."),
961 paddress (gdbarch, pc));
964 /* See elf_gnu_ifunc_resolve_name for its real implementation. */
967 stub_gnu_ifunc_resolve_name (const char *function_name,
968 CORE_ADDR *function_address_p)
970 error (_("GDB cannot resolve STT_GNU_IFUNC symbol \"%s\" without "
971 "the ELF support compiled in."),
975 /* See elf_gnu_ifunc_resolver_stop for its real implementation. */
978 stub_gnu_ifunc_resolver_stop (struct breakpoint *b)
980 internal_error (__FILE__, __LINE__,
981 _("elf_gnu_ifunc_resolver_stop cannot be reached."));
984 /* See elf_gnu_ifunc_resolver_return_stop for its real implementation. */
987 stub_gnu_ifunc_resolver_return_stop (struct breakpoint *b)
989 internal_error (__FILE__, __LINE__,
990 _("elf_gnu_ifunc_resolver_return_stop cannot be reached."));
993 /* See elf_gnu_ifunc_fns for its real implementation. */
995 static const struct gnu_ifunc_fns stub_gnu_ifunc_fns =
997 stub_gnu_ifunc_resolve_addr,
998 stub_gnu_ifunc_resolve_name,
999 stub_gnu_ifunc_resolver_stop,
1000 stub_gnu_ifunc_resolver_return_stop,
1003 /* A placeholder for &elf_gnu_ifunc_fns. */
1005 const struct gnu_ifunc_fns *gnu_ifunc_fns_p = &stub_gnu_ifunc_fns;
1009 /* Return leading symbol character for a BFD. If BFD is NULL,
1010 return the leading symbol character from the main objfile. */
1013 get_symbol_leading_char (bfd *abfd)
1016 return bfd_get_symbol_leading_char (abfd);
1017 if (symfile_objfile != NULL && symfile_objfile->obfd != NULL)
1018 return bfd_get_symbol_leading_char (symfile_objfile->obfd);
1022 /* See minsyms.h. */
1024 minimal_symbol_reader::minimal_symbol_reader (struct objfile *obj)
1026 m_msym_bunch (NULL),
1027 /* Note that presetting m_msym_bunch_index to BUNCH_SIZE causes the
1028 first call to save a minimal symbol to allocate the memory for
1030 m_msym_bunch_index (BUNCH_SIZE),
1035 /* Discard the currently collected minimal symbols, if any. If we wish
1036 to save them for later use, we must have already copied them somewhere
1037 else before calling this function.
1039 FIXME: We could allocate the minimal symbol bunches on their own
1040 obstack and then simply blow the obstack away when we are done with
1041 it. Is it worth the extra trouble though? */
1043 minimal_symbol_reader::~minimal_symbol_reader ()
1045 struct msym_bunch *next;
1047 while (m_msym_bunch != NULL)
1049 next = m_msym_bunch->next;
1050 xfree (m_msym_bunch);
1051 m_msym_bunch = next;
1055 /* See minsyms.h. */
1058 minimal_symbol_reader::record (const char *name, CORE_ADDR address,
1059 enum minimal_symbol_type ms_type)
1066 case mst_text_gnu_ifunc:
1068 case mst_solib_trampoline:
1069 section = SECT_OFF_TEXT (m_objfile);
1072 case mst_data_gnu_ifunc:
1074 section = SECT_OFF_DATA (m_objfile);
1078 section = SECT_OFF_BSS (m_objfile);
1084 record_with_info (name, address, ms_type, section);
1087 /* Convert an enumerator of type minimal_symbol_type to its string
1091 mst_str (minimal_symbol_type t)
1093 #define MST_TO_STR(x) case x: return #x;
1096 MST_TO_STR (mst_unknown);
1097 MST_TO_STR (mst_text);
1098 MST_TO_STR (mst_text_gnu_ifunc);
1099 MST_TO_STR (mst_slot_got_plt);
1100 MST_TO_STR (mst_data);
1101 MST_TO_STR (mst_bss);
1102 MST_TO_STR (mst_abs);
1103 MST_TO_STR (mst_solib_trampoline);
1104 MST_TO_STR (mst_file_text);
1105 MST_TO_STR (mst_file_data);
1106 MST_TO_STR (mst_file_bss);
1114 /* See minsyms.h. */
1116 struct minimal_symbol *
1117 minimal_symbol_reader::record_full (const char *name, int name_len,
1118 bool copy_name, CORE_ADDR address,
1119 enum minimal_symbol_type ms_type,
1122 struct msym_bunch *newobj;
1123 struct minimal_symbol *msymbol;
1125 /* Don't put gcc_compiled, __gnu_compiled_cplus, and friends into
1126 the minimal symbols, because if there is also another symbol
1127 at the same address (e.g. the first function of the file),
1128 lookup_minimal_symbol_by_pc would have no way of getting the
1130 if (ms_type == mst_file_text && name[0] == 'g'
1131 && (strcmp (name, GCC_COMPILED_FLAG_SYMBOL) == 0
1132 || strcmp (name, GCC2_COMPILED_FLAG_SYMBOL) == 0))
1135 /* It's safe to strip the leading char here once, since the name
1136 is also stored stripped in the minimal symbol table. */
1137 if (name[0] == get_symbol_leading_char (m_objfile->obfd))
1143 if (ms_type == mst_file_text && startswith (name, "__gnu_compiled"))
1146 if (symtab_create_debug >= 2)
1147 printf_unfiltered ("Recording minsym: %-21s %18s %4d %s\n",
1148 mst_str (ms_type), hex_string (address), section, name);
1150 if (m_msym_bunch_index == BUNCH_SIZE)
1152 newobj = XCNEW (struct msym_bunch);
1153 m_msym_bunch_index = 0;
1154 newobj->next = m_msym_bunch;
1155 m_msym_bunch = newobj;
1157 msymbol = &m_msym_bunch->contents[m_msym_bunch_index];
1158 MSYMBOL_SET_LANGUAGE (msymbol, language_auto,
1159 &m_objfile->per_bfd->storage_obstack);
1160 MSYMBOL_SET_NAMES (msymbol, name, name_len, copy_name, m_objfile);
1162 SET_MSYMBOL_VALUE_ADDRESS (msymbol, address);
1163 MSYMBOL_SECTION (msymbol) = section;
1165 MSYMBOL_TYPE (msymbol) = ms_type;
1167 /* If we already read minimal symbols for this objfile, then don't
1168 ever allocate a new one. */
1169 if (!m_objfile->per_bfd->minsyms_read)
1171 m_msym_bunch_index++;
1172 m_objfile->per_bfd->n_minsyms++;
1178 /* Compare two minimal symbols by address and return a signed result based
1179 on unsigned comparisons, so that we sort into unsigned numeric order.
1180 Within groups with the same address, sort by name. */
1183 compare_minimal_symbols (const void *fn1p, const void *fn2p)
1185 const struct minimal_symbol *fn1;
1186 const struct minimal_symbol *fn2;
1188 fn1 = (const struct minimal_symbol *) fn1p;
1189 fn2 = (const struct minimal_symbol *) fn2p;
1191 if (MSYMBOL_VALUE_RAW_ADDRESS (fn1) < MSYMBOL_VALUE_RAW_ADDRESS (fn2))
1193 return (-1); /* addr 1 is less than addr 2. */
1195 else if (MSYMBOL_VALUE_RAW_ADDRESS (fn1) > MSYMBOL_VALUE_RAW_ADDRESS (fn2))
1197 return (1); /* addr 1 is greater than addr 2. */
1200 /* addrs are equal: sort by name */
1202 const char *name1 = MSYMBOL_LINKAGE_NAME (fn1);
1203 const char *name2 = MSYMBOL_LINKAGE_NAME (fn2);
1205 if (name1 && name2) /* both have names */
1206 return strcmp (name1, name2);
1208 return 1; /* fn1 has no name, so it is "less". */
1209 else if (name1) /* fn2 has no name, so it is "less". */
1212 return (0); /* Neither has a name, so they're equal. */
1216 /* Compact duplicate entries out of a minimal symbol table by walking
1217 through the table and compacting out entries with duplicate addresses
1218 and matching names. Return the number of entries remaining.
1220 On entry, the table resides between msymbol[0] and msymbol[mcount].
1221 On exit, it resides between msymbol[0] and msymbol[result_count].
1223 When files contain multiple sources of symbol information, it is
1224 possible for the minimal symbol table to contain many duplicate entries.
1225 As an example, SVR4 systems use ELF formatted object files, which
1226 usually contain at least two different types of symbol tables (a
1227 standard ELF one and a smaller dynamic linking table), as well as
1228 DWARF debugging information for files compiled with -g.
1230 Without compacting, the minimal symbol table for gdb itself contains
1231 over a 1000 duplicates, about a third of the total table size. Aside
1232 from the potential trap of not noticing that two successive entries
1233 identify the same location, this duplication impacts the time required
1234 to linearly scan the table, which is done in a number of places. So we
1235 just do one linear scan here and toss out the duplicates.
1237 Note that we are not concerned here about recovering the space that
1238 is potentially freed up, because the strings themselves are allocated
1239 on the storage_obstack, and will get automatically freed when the symbol
1240 table is freed. The caller can free up the unused minimal symbols at
1241 the end of the compacted region if their allocation strategy allows it.
1243 Also note we only go up to the next to last entry within the loop
1244 and then copy the last entry explicitly after the loop terminates.
1246 Since the different sources of information for each symbol may
1247 have different levels of "completeness", we may have duplicates
1248 that have one entry with type "mst_unknown" and the other with a
1249 known type. So if the one we are leaving alone has type mst_unknown,
1250 overwrite its type with the type from the one we are compacting out. */
1253 compact_minimal_symbols (struct minimal_symbol *msymbol, int mcount,
1254 struct objfile *objfile)
1256 struct minimal_symbol *copyfrom;
1257 struct minimal_symbol *copyto;
1261 copyfrom = copyto = msymbol;
1262 while (copyfrom < msymbol + mcount - 1)
1264 if (MSYMBOL_VALUE_RAW_ADDRESS (copyfrom)
1265 == MSYMBOL_VALUE_RAW_ADDRESS ((copyfrom + 1))
1266 && MSYMBOL_SECTION (copyfrom) == MSYMBOL_SECTION (copyfrom + 1)
1267 && strcmp (MSYMBOL_LINKAGE_NAME (copyfrom),
1268 MSYMBOL_LINKAGE_NAME ((copyfrom + 1))) == 0)
1270 if (MSYMBOL_TYPE ((copyfrom + 1)) == mst_unknown)
1272 MSYMBOL_TYPE ((copyfrom + 1)) = MSYMBOL_TYPE (copyfrom);
1277 *copyto++ = *copyfrom++;
1279 *copyto++ = *copyfrom++;
1280 mcount = copyto - msymbol;
1285 /* Build (or rebuild) the minimal symbol hash tables. This is necessary
1286 after compacting or sorting the table since the entries move around
1287 thus causing the internal minimal_symbol pointers to become jumbled. */
1290 build_minimal_symbol_hash_tables (struct objfile *objfile)
1293 struct minimal_symbol *msym;
1295 /* Clear the hash tables. */
1296 for (i = 0; i < MINIMAL_SYMBOL_HASH_SIZE; i++)
1298 objfile->per_bfd->msymbol_hash[i] = 0;
1299 objfile->per_bfd->msymbol_demangled_hash[i] = 0;
1302 /* Now, (re)insert the actual entries. */
1303 for ((i = objfile->per_bfd->minimal_symbol_count,
1304 msym = objfile->per_bfd->msymbols);
1308 msym->hash_next = 0;
1309 add_minsym_to_hash_table (msym, objfile->per_bfd->msymbol_hash);
1311 msym->demangled_hash_next = 0;
1312 if (MSYMBOL_SEARCH_NAME (msym) != MSYMBOL_LINKAGE_NAME (msym))
1313 add_minsym_to_demangled_hash_table (msym, objfile);
1317 /* Add the minimal symbols in the existing bunches to the objfile's official
1318 minimal symbol table. In most cases there is no minimal symbol table yet
1319 for this objfile, and the existing bunches are used to create one. Once
1320 in a while (for shared libraries for example), we add symbols (e.g. common
1321 symbols) to an existing objfile.
1323 Because of the way minimal symbols are collected, we generally have no way
1324 of knowing what source language applies to any particular minimal symbol.
1325 Specifically, we have no way of knowing if the minimal symbol comes from a
1326 C++ compilation unit or not. So for the sake of supporting cached
1327 demangled C++ names, we have no choice but to try and demangle each new one
1328 that comes in. If the demangling succeeds, then we assume it is a C++
1329 symbol and set the symbol's language and demangled name fields
1330 appropriately. Note that in order to avoid unnecessary demanglings, and
1331 allocating obstack space that subsequently can't be freed for the demangled
1332 names, we mark all newly added symbols with language_auto. After
1333 compaction of the minimal symbols, we go back and scan the entire minimal
1334 symbol table looking for these new symbols. For each new symbol we attempt
1335 to demangle it, and if successful, record it as a language_cplus symbol
1336 and cache the demangled form on the symbol obstack. Symbols which don't
1337 demangle are marked as language_unknown symbols, which inhibits future
1338 attempts to demangle them if we later add more minimal symbols. */
1341 minimal_symbol_reader::install ()
1345 struct msym_bunch *bunch;
1346 struct minimal_symbol *msymbols;
1349 if (m_objfile->per_bfd->minsyms_read)
1352 if (m_msym_count > 0)
1354 if (symtab_create_debug)
1356 fprintf_unfiltered (gdb_stdlog,
1357 "Installing %d minimal symbols of objfile %s.\n",
1358 m_msym_count, objfile_name (m_objfile));
1361 /* Allocate enough space in the obstack, into which we will gather the
1362 bunches of new and existing minimal symbols, sort them, and then
1363 compact out the duplicate entries. Once we have a final table,
1364 we will give back the excess space. */
1366 alloc_count = m_msym_count + m_objfile->per_bfd->minimal_symbol_count + 1;
1367 obstack_blank (&m_objfile->per_bfd->storage_obstack,
1368 alloc_count * sizeof (struct minimal_symbol));
1369 msymbols = (struct minimal_symbol *)
1370 obstack_base (&m_objfile->per_bfd->storage_obstack);
1372 /* Copy in the existing minimal symbols, if there are any. */
1374 if (m_objfile->per_bfd->minimal_symbol_count)
1375 memcpy ((char *) msymbols, (char *) m_objfile->per_bfd->msymbols,
1376 m_objfile->per_bfd->minimal_symbol_count * sizeof (struct minimal_symbol));
1378 /* Walk through the list of minimal symbol bunches, adding each symbol
1379 to the new contiguous array of symbols. Note that we start with the
1380 current, possibly partially filled bunch (thus we use the current
1381 msym_bunch_index for the first bunch we copy over), and thereafter
1382 each bunch is full. */
1384 mcount = m_objfile->per_bfd->minimal_symbol_count;
1386 for (bunch = m_msym_bunch; bunch != NULL; bunch = bunch->next)
1388 for (bindex = 0; bindex < m_msym_bunch_index; bindex++, mcount++)
1389 msymbols[mcount] = bunch->contents[bindex];
1390 m_msym_bunch_index = BUNCH_SIZE;
1393 /* Sort the minimal symbols by address. */
1395 qsort (msymbols, mcount, sizeof (struct minimal_symbol),
1396 compare_minimal_symbols);
1398 /* Compact out any duplicates, and free up whatever space we are
1401 mcount = compact_minimal_symbols (msymbols, mcount, m_objfile);
1403 ssize_t shrink_bytes
1404 = (mcount + 1 - alloc_count) * sizeof (struct minimal_symbol);
1405 obstack_blank_fast (&m_objfile->per_bfd->storage_obstack, shrink_bytes);
1406 msymbols = (struct minimal_symbol *)
1407 obstack_finish (&m_objfile->per_bfd->storage_obstack);
1409 /* We also terminate the minimal symbol table with a "null symbol",
1410 which is *not* included in the size of the table. This makes it
1411 easier to find the end of the table when we are handed a pointer
1412 to some symbol in the middle of it. Zero out the fields in the
1413 "null symbol" allocated at the end of the array. Note that the
1414 symbol count does *not* include this null symbol, which is why it
1415 is indexed by mcount and not mcount-1. */
1417 memset (&msymbols[mcount], 0, sizeof (struct minimal_symbol));
1419 /* Attach the minimal symbol table to the specified objfile.
1420 The strings themselves are also located in the storage_obstack
1423 m_objfile->per_bfd->minimal_symbol_count = mcount;
1424 m_objfile->per_bfd->msymbols = msymbols;
1426 /* Now build the hash tables; we can't do this incrementally
1427 at an earlier point since we weren't finished with the obstack
1428 yet. (And if the msymbol obstack gets moved, all the internal
1429 pointers to other msymbols need to be adjusted.) */
1430 build_minimal_symbol_hash_tables (m_objfile);
1434 /* See minsyms.h. */
1437 terminate_minimal_symbol_table (struct objfile *objfile)
1439 if (! objfile->per_bfd->msymbols)
1440 objfile->per_bfd->msymbols = XOBNEW (&objfile->per_bfd->storage_obstack,
1444 struct minimal_symbol *m
1445 = &objfile->per_bfd->msymbols[objfile->per_bfd->minimal_symbol_count];
1447 memset (m, 0, sizeof (*m));
1448 /* Don't rely on these enumeration values being 0's. */
1449 MSYMBOL_TYPE (m) = mst_unknown;
1450 MSYMBOL_SET_LANGUAGE (m, language_unknown,
1451 &objfile->per_bfd->storage_obstack);
1455 /* Check if PC is in a shared library trampoline code stub.
1456 Return minimal symbol for the trampoline entry or NULL if PC is not
1457 in a trampoline code stub. */
1459 static struct minimal_symbol *
1460 lookup_solib_trampoline_symbol_by_pc (CORE_ADDR pc)
1462 bound_minimal_symbol msymbol
1463 = lookup_minimal_symbol_by_pc_section (pc, NULL,
1464 lookup_msym_prefer::TRAMPOLINE);
1466 if (msymbol.minsym != NULL
1467 && MSYMBOL_TYPE (msymbol.minsym) == mst_solib_trampoline)
1468 return msymbol.minsym;
1472 /* If PC is in a shared library trampoline code stub, return the
1473 address of the `real' function belonging to the stub.
1474 Return 0 if PC is not in a trampoline code stub or if the real
1475 function is not found in the minimal symbol table.
1477 We may fail to find the right function if a function with the
1478 same name is defined in more than one shared library, but this
1479 is considered bad programming style. We could return 0 if we find
1480 a duplicate function in case this matters someday. */
1483 find_solib_trampoline_target (struct frame_info *frame, CORE_ADDR pc)
1485 struct minimal_symbol *tsymbol = lookup_solib_trampoline_symbol_by_pc (pc);
1487 if (tsymbol != NULL)
1489 for (objfile *objfile : current_program_space->objfiles ())
1491 for (minimal_symbol *msymbol : objfile->msymbols ())
1493 /* Also handle minimal symbols pointing to function
1495 if ((MSYMBOL_TYPE (msymbol) == mst_text
1496 || MSYMBOL_TYPE (msymbol) == mst_text_gnu_ifunc
1497 || MSYMBOL_TYPE (msymbol) == mst_data
1498 || MSYMBOL_TYPE (msymbol) == mst_data_gnu_ifunc)
1499 && strcmp (MSYMBOL_LINKAGE_NAME (msymbol),
1500 MSYMBOL_LINKAGE_NAME (tsymbol)) == 0)
1504 /* Ignore data symbols that are not function
1506 if (msymbol_is_function (objfile, msymbol, &func))
1515 /* See minsyms.h. */
1518 minimal_symbol_upper_bound (struct bound_minimal_symbol minsym)
1522 struct obj_section *obj_section;
1524 struct minimal_symbol *msymbol;
1526 gdb_assert (minsym.minsym != NULL);
1528 /* If the minimal symbol has a size, use it. Otherwise use the
1529 lesser of the next minimal symbol in the same section, or the end
1530 of the section, as the end of the function. */
1532 if (MSYMBOL_SIZE (minsym.minsym) != 0)
1533 return BMSYMBOL_VALUE_ADDRESS (minsym) + MSYMBOL_SIZE (minsym.minsym);
1535 /* Step over other symbols at this same address, and symbols in
1536 other sections, to find the next symbol in this section with a
1537 different address. */
1539 msymbol = minsym.minsym;
1540 section = MSYMBOL_SECTION (msymbol);
1541 for (i = 1; MSYMBOL_LINKAGE_NAME (msymbol + i) != NULL; i++)
1543 if ((MSYMBOL_VALUE_RAW_ADDRESS (msymbol + i)
1544 != MSYMBOL_VALUE_RAW_ADDRESS (msymbol))
1545 && MSYMBOL_SECTION (msymbol + i) == section)
1549 obj_section = MSYMBOL_OBJ_SECTION (minsym.objfile, minsym.minsym);
1550 if (MSYMBOL_LINKAGE_NAME (msymbol + i) != NULL
1551 && (MSYMBOL_VALUE_ADDRESS (minsym.objfile, msymbol + i)
1552 < obj_section_endaddr (obj_section)))
1553 result = MSYMBOL_VALUE_ADDRESS (minsym.objfile, msymbol + i);
1555 /* We got the start address from the last msymbol in the objfile.
1556 So the end address is the end of the section. */
1557 result = obj_section_endaddr (obj_section);