1 /* Read ELF (Executable and Linking Format) object files for GDB.
2 Copyright 1991, 1992 Free Software Foundation, Inc.
3 Written by Fred Fish at Cygnus Support.
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 2 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, write to the Free Software
19 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
23 #include <time.h> /* For time_t in libbfd.h. */
24 #include <sys/types.h> /* For time_t, if not in time.h. */
25 #include "libbfd.h" /* For bfd_elf_find_section */
31 #include "stabsread.h"
32 #include "gdb-stabs.h"
33 #include "complaints.h"
37 /* The struct elfinfo is available only during ELF symbol table and
38 psymtab reading. It is destroyed at the complation of psymtab-reading.
39 It's local to elf_symfile_read. */
42 file_ptr dboffset; /* Offset to dwarf debug section */
43 unsigned int dbsize; /* Size of dwarf debug section */
44 file_ptr lnoffset; /* Offset to dwarf line number section */
45 unsigned int lnsize; /* Size of dwarf line number section */
46 asection *stabsect; /* Section pointer for .stab section */
47 asection *stabindexsect; /* Section pointer for .stab.index section */
48 asection *mdebugsect; /* Section pointer for .mdebug section */
51 /* Various things we might complain about... */
53 struct complaint section_info_complaint =
54 {"elf/stab section information %s without a preceding file symbol", 0, 0};
56 struct complaint section_info_dup_complaint =
57 {"duplicated elf/stab section information for %s", 0, 0};
59 struct complaint stab_info_mismatch_complaint =
60 {"elf/stab section information missing for %s", 0, 0};
62 struct complaint stab_info_questionable_complaint =
63 {"elf/stab section information questionable for %s", 0, 0};
66 elf_symfile_init PARAMS ((struct objfile *));
69 elf_new_init PARAMS ((struct objfile *));
72 elf_symfile_read PARAMS ((struct objfile *, struct section_offsets *, int));
75 elf_symfile_finish PARAMS ((struct objfile *));
78 elf_symtab_read PARAMS ((bfd *, CORE_ADDR, struct objfile *));
81 free_elfinfo PARAMS ((void *));
83 static struct section_offsets *
84 elf_symfile_offsets PARAMS ((struct objfile *, CORE_ADDR));
87 record_minimal_symbol_and_info PARAMS ((char *, CORE_ADDR,
88 enum minimal_symbol_type, char *,
92 elf_locate_sections PARAMS ((bfd *, asection *, void *));
94 /* We are called once per section from elf_symfile_read. We
95 need to examine each section we are passed, check to see
96 if it is something we are interested in processing, and
97 if so, stash away some access information for the section.
99 For now we recognize the dwarf debug information sections and
100 line number sections from matching their section names. The
101 ELF definition is no real help here since it has no direct
102 knowledge of DWARF (by design, so any debugging format can be
105 We also recognize the ".stab" sections used by the Sun compilers
106 released with Solaris 2.
108 FIXME: The section names should not be hardwired strings (what
109 should they be? I don't think most object file formats have enough
110 section flags to specify what kind of debug section it is
114 elf_locate_sections (ignore_abfd, sectp, eip)
119 register struct elfinfo *ei;
121 ei = (struct elfinfo *) eip;
122 if (STREQ (sectp -> name, ".debug"))
124 ei -> dboffset = sectp -> filepos;
125 ei -> dbsize = bfd_get_section_size_before_reloc (sectp);
127 else if (STREQ (sectp -> name, ".line"))
129 ei -> lnoffset = sectp -> filepos;
130 ei -> lnsize = bfd_get_section_size_before_reloc (sectp);
132 else if (STREQ (sectp -> name, ".stab"))
134 ei -> stabsect = sectp;
136 else if (STREQ (sectp -> name, ".stab.index"))
138 ei -> stabindexsect = sectp;
140 else if (STREQ (sectp -> name, ".mdebug"))
142 ei -> mdebugsect = sectp;
146 #if 0 /* Currently unused */
149 elf_interpreter (abfd)
156 interp_sec = bfd_get_section_by_name (abfd, ".interp");
159 size = bfd_section_size (abfd, interp_sec);
160 interp = alloca (size);
161 if (bfd_get_section_contents (abfd, interp_sec, interp, (file_ptr)0,
164 interp = savestring (interp, size - 1);
177 record_minimal_symbol_and_info (name, address, ms_type, info, objfile)
180 enum minimal_symbol_type ms_type;
181 char *info; /* FIXME, is this really char *? */
182 struct objfile *objfile;
186 /* Guess the section from the type. This is likely to be wrong in
192 section = SECT_OFF_TEXT;
193 #ifdef SMASH_TEXT_ADDRESS
194 SMASH_TEXT_ADDRESS (address);
199 section = SECT_OFF_DATA;
203 section = SECT_OFF_BSS;
210 name = obsavestring (name, strlen (name), &objfile -> symbol_obstack);
211 prim_record_minimal_symbol_and_info (name, address, ms_type, info, section,
219 elf_symtab_read -- read the symbol table of an ELF file
223 void elf_symtab_read (bfd *abfd, CORE_ADDR addr,
224 struct objfile *objfile)
228 Given an open bfd, a base address to relocate symbols to, and a
229 flag that specifies whether or not this bfd is for an executable
230 or not (may be shared library for example), add all the global
231 function and data symbols to the minimal symbol table.
233 In stabs-in-ELF, as implemented by Sun, there are some local symbols
234 defined in the ELF symbol table, which can be used to locate
235 the beginnings of sections from each ".o" file that was linked to
236 form the executable objfile. We gather any such info and record it
237 in data structures hung off the objfile's private data.
242 elf_symtab_read (abfd, addr, objfile)
245 struct objfile *objfile;
249 asymbol **symbol_table;
250 long number_of_symbols;
253 struct cleanup *back_to;
255 enum minimal_symbol_type ms_type;
256 /* If sectinfo is nonNULL, it contains section info that should end up
257 filed in the objfile. */
258 struct stab_section_info *sectinfo = NULL;
259 /* If filesym is nonzero, it points to a file symbol, but we haven't
260 seen any section info for it yet. */
261 asymbol *filesym = 0;
262 struct dbx_symfile_info *dbx = (struct dbx_symfile_info *)
263 objfile->sym_stab_info;
266 storage_needed = bfd_get_symtab_upper_bound (abfd);
267 if (storage_needed < 0)
268 error ("Can't read symbols from %s: %s", bfd_get_filename (abfd),
269 bfd_errmsg (bfd_get_error ()));
270 if (storage_needed > 0)
272 symbol_table = (asymbol **) xmalloc (storage_needed);
273 back_to = make_cleanup (free, symbol_table);
274 number_of_symbols = bfd_canonicalize_symtab (abfd, symbol_table);
275 if (number_of_symbols < 0)
276 error ("Can't read symbols from %s: %s", bfd_get_filename (abfd),
277 bfd_errmsg (bfd_get_error ()));
278 for (i = 0; i < number_of_symbols; i++)
280 sym = symbol_table[i];
281 if (sym -> name == NULL || *sym -> name == '\0')
283 /* Skip names that don't exist (shouldn't happen), or names
284 that are null strings (may happen). */
287 if (sym -> flags & BSF_FILE)
289 /* STT_FILE debugging symbol that helps stabs-in-elf debugging.
290 Chain any old one onto the objfile; remember new sym. */
291 if (sectinfo != NULL)
293 sectinfo -> next = dbx -> stab_section_info;
294 dbx -> stab_section_info = sectinfo;
299 else if (sym -> flags & (BSF_GLOBAL | BSF_LOCAL | BSF_WEAK))
301 /* Select global/local/weak symbols. Note that bfd puts abs
302 symbols in their own section, so all symbols we are
303 interested in will have a section. */
304 /* Bfd symbols are section relative. */
305 symaddr = sym -> value + sym -> section -> vma;
306 /* Relocate all non-absolute symbols by base address. */
307 if (sym -> section != &bfd_abs_section)
311 /* For non-absolute symbols, use the type of the section
312 they are relative to, to intuit text/data. Bfd provides
313 no way of figuring this out for absolute symbols. */
314 if (sym -> section == &bfd_und_section
315 && (sym -> flags & BSF_GLOBAL)
316 && (sym -> flags & BSF_FUNCTION))
318 /* Symbol is a reference to a function defined in
320 If its value is non zero then it is usually the
321 absolute address of the corresponding entry in
322 the procedure linkage table.
323 If its value is zero then the dynamic linker has to
324 resolve the symbol. We are unable to find any
325 meaningful address for this symbol in the
326 executable file, so we skip it.
327 Irix 5 has a zero value for all shared library functions
328 in the main symbol table. The dynamic symbol table
329 would provide the right values, but BFD currently
330 cannot handle dynamic ELF symbol tables. */
331 ms_type = mst_solib_trampoline;
332 symaddr = sym -> value;
336 else if (sym -> section == &bfd_abs_section)
340 else if (sym -> section -> flags & SEC_CODE)
342 if (sym -> flags & BSF_GLOBAL)
346 else if (sym->name[0] == '.' && sym->name[1] == 'L')
347 /* Looks like a compiler-generated label. Skip it.
348 The assembler should be skipping these (to keep
349 executables small), but apparently with gcc on the
350 delta m88k SVR4, it loses. So to have us check too
351 should be harmless (but I encourage people to fix this
352 in the assembler instead of adding checks here). */
356 ms_type = mst_file_text;
359 else if (sym -> section -> flags & SEC_ALLOC)
361 if (sym -> flags & BSF_GLOBAL)
363 if (sym -> section -> flags & SEC_LOAD)
372 else if (sym -> flags & BSF_LOCAL)
374 /* Named Local variable in a Data section. Check its
375 name for stabs-in-elf. The STREQ macro checks the
376 first character inline, so we only actually do a
377 strcmp function call on names that start with 'B'
379 index = SECT_OFF_MAX;
380 if (STREQ ("Bbss.bss", sym -> name))
382 index = SECT_OFF_BSS;
384 else if (STREQ ("Ddata.data", sym -> name))
386 index = SECT_OFF_DATA;
388 else if (STREQ ("Drodata.rodata", sym -> name))
390 index = SECT_OFF_RODATA;
392 if (index != SECT_OFF_MAX)
394 /* Found a special local symbol. Allocate a
395 sectinfo, if needed, and fill it in. */
396 if (sectinfo == NULL)
398 sectinfo = (struct stab_section_info *)
399 xmmalloc (objfile -> md, sizeof (*sectinfo));
400 memset ((PTR) sectinfo, 0, sizeof (*sectinfo));
403 complain (§ion_info_complaint,
408 sectinfo -> filename =
409 (char *) filesym -> name;
412 if (sectinfo -> sections[index] != 0)
414 complain (§ion_info_dup_complaint,
415 sectinfo -> filename);
417 /* Bfd symbols are section relative. */
418 symaddr = sym -> value + sym -> section -> vma;
419 /* Relocate non-absolute symbols by base address. */
420 if (sym -> section != &bfd_abs_section)
424 sectinfo -> sections[index] = symaddr;
425 /* The special local symbols don't go in the
426 minimal symbol table, so ignore this one. */
429 /* Not a special stabs-in-elf symbol, do regular
430 symbol processing. */
431 if (sym -> section -> flags & SEC_LOAD)
433 ms_type = mst_file_data;
437 ms_type = mst_file_bss;
442 ms_type = mst_unknown;
447 /* FIXME: Solaris2 shared libraries include lots of
448 odd "absolute" and "undefined" symbols, that play
449 hob with actions like finding what function the PC
450 is in. Ignore them if they aren't text, data, or bss. */
451 /* ms_type = mst_unknown; */
452 continue; /* Skip this symbol. */
454 /* Pass symbol size field in via BFD. FIXME!!! */
455 size = ((elf_symbol_type *) sym) -> internal_elf_sym.st_size;
456 record_minimal_symbol_and_info ((char *) sym -> name, symaddr,
457 ms_type, (PTR) size, objfile);
460 do_cleanups (back_to);
464 /* Scan and build partial symbols for a symbol file.
465 We have been initialized by a call to elf_symfile_init, which
466 currently does nothing.
468 SECTION_OFFSETS is a set of offsets to apply to relocate the symbols
469 in each section. We simplify it down to a single offset for all
472 MAINLINE is true if we are reading the main symbol
473 table (as opposed to a shared lib or dynamically loaded file).
475 This function only does the minimum work necessary for letting the
476 user "name" things symbolically; it does not read the entire symtab.
477 Instead, it reads the external and static symbols and puts them in partial
478 symbol tables. When more extensive information is requested of a
479 file, the corresponding partial symbol table is mutated into a full
480 fledged symbol table by going back and reading the symbols
483 We look for sections with specific names, to tell us what debug
484 format to look for: FIXME!!!
486 dwarf_build_psymtabs() builds psymtabs for DWARF symbols;
487 elfstab_build_psymtabs() handles STABS symbols;
488 mdebug_build_psymtabs() handles ECOFF debugging information.
490 Note that ELF files have a "minimal" symbol table, which looks a lot
491 like a COFF symbol table, but has only the minimal information necessary
492 for linking. We process this also, and use the information to
493 build gdb's minimal symbol table. This gives us some minimal debugging
494 capability even for files compiled without -g. */
497 elf_symfile_read (objfile, section_offsets, mainline)
498 struct objfile *objfile;
499 struct section_offsets *section_offsets;
502 bfd *abfd = objfile->obfd;
504 struct cleanup *back_to;
507 init_minimal_symbol_collection ();
508 back_to = make_cleanup (discard_minimal_symbols, 0);
510 memset ((char *) &ei, 0, sizeof (ei));
512 /* Allocate struct to keep track of the symfile */
513 objfile->sym_stab_info = (PTR)
514 xmmalloc (objfile -> md, sizeof (struct dbx_symfile_info));
515 memset ((char *) objfile->sym_stab_info, 0, sizeof (struct dbx_symfile_info));
516 make_cleanup (free_elfinfo, (PTR) objfile);
518 /* Process the normal ELF symbol table first. This may write some
519 chain of info into the dbx_symfile_info in objfile->sym_stab_info,
520 which can later be used by elfstab_offset_sections. */
522 /* FIXME, should take a section_offsets param, not just an offset. */
523 offset = ANOFFSET (section_offsets, 0);
524 elf_symtab_read (abfd, offset, objfile);
526 /* Now process debugging information, which is contained in
527 special ELF sections. We first have to find them... */
529 bfd_map_over_sections (abfd, elf_locate_sections, (PTR) &ei);
530 if (ei.dboffset && ei.lnoffset)
533 dwarf_build_psymtabs (objfile,
534 section_offsets, mainline,
535 ei.dboffset, ei.dbsize,
536 ei.lnoffset, ei.lnsize);
542 /* FIXME: Sun didn't really know how to implement this well.
543 They made .stab sections that don't point to the .stabstr
544 section with the sh_link field. BFD doesn't make string table
545 sections visible to the caller. So we have to search the
546 ELF section table, not the BFD section table, for the string
548 struct elf32_internal_shdr *elf_sect;
550 elf_sect = bfd_elf_find_section (abfd, ".stabstr");
552 elfstab_build_psymtabs (objfile,
555 ei.stabsect->filepos, /* .stab offset */
556 bfd_get_section_size_before_reloc (ei.stabsect),/* .stab size */
557 (file_ptr) elf_sect->sh_offset, /* .stabstr offset */
558 elf_sect->sh_size); /* .stabstr size */
562 const struct ecoff_debug_swap *swap;
564 /* .mdebug section, presumably holding ECOFF debugging
566 swap = get_elf_backend_data (abfd)->elf_backend_ecoff_debug_swap;
568 elfmdebug_build_psymtabs (objfile, swap, ei.mdebugsect,
572 if (!have_partial_symbols ())
575 printf_filtered ("(no debugging symbols found)...");
579 /* Install any minimal symbols that have been collected as the current
580 minimal symbols for this objfile. */
582 install_minimal_symbols (objfile);
584 do_cleanups (back_to);
587 /* This cleans up the objfile's sym_stab_info pointer, and the chain of
588 stab_section_info's, that might be dangling from it. */
594 struct objfile *objfile = (struct objfile *)objp;
595 struct dbx_symfile_info *dbxinfo = (struct dbx_symfile_info *)
596 objfile->sym_stab_info;
597 struct stab_section_info *ssi, *nssi;
599 ssi = dbxinfo->stab_section_info;
603 mfree (objfile->md, ssi);
607 dbxinfo->stab_section_info = 0; /* Just say No mo info about this. */
611 /* Initialize anything that needs initializing when a completely new symbol
612 file is specified (not just adding some symbols from another file, e.g. a
615 We reinitialize buildsym, since we may be reading stabs from an ELF file. */
618 elf_new_init (ignore)
619 struct objfile *ignore;
621 stabsread_new_init ();
622 buildsym_new_init ();
625 /* Perform any local cleanups required when we are done with a particular
626 objfile. I.E, we are in the process of discarding all symbol information
627 for an objfile, freeing up all memory held for it, and unlinking the
628 objfile struct from the global list of known objfiles. */
631 elf_symfile_finish (objfile)
632 struct objfile *objfile;
634 if (objfile -> sym_stab_info != NULL)
636 mfree (objfile -> md, objfile -> sym_stab_info);
640 /* ELF specific initialization routine for reading symbols.
642 It is passed a pointer to a struct sym_fns which contains, among other
643 things, the BFD for the file whose symbols are being read, and a slot for
644 a pointer to "private data" which we can fill with goodies.
646 For now at least, we have nothing in particular to do, so this function is
650 elf_symfile_init (ignore)
651 struct objfile *ignore;
655 /* ELF specific parsing routine for section offsets.
657 Plain and simple for now. */
660 struct section_offsets *
661 elf_symfile_offsets (objfile, addr)
662 struct objfile *objfile;
665 struct section_offsets *section_offsets;
668 objfile->num_sections = SECT_OFF_MAX;
669 section_offsets = (struct section_offsets *)
670 obstack_alloc (&objfile -> psymbol_obstack,
671 sizeof (struct section_offsets)
672 + sizeof (section_offsets->offsets) * (SECT_OFF_MAX-1));
674 for (i = 0; i < SECT_OFF_MAX; i++)
675 ANOFFSET (section_offsets, i) = addr;
677 return section_offsets;
680 /* When handling an ELF file that contains Sun STABS debug info,
681 some of the debug info is relative to the particular chunk of the
682 section that was generated in its individual .o file. E.g.
683 offsets to static variables are relative to the start of the data
684 segment *for that module before linking*. This information is
685 painfully squirreled away in the ELF symbol table as local symbols
686 with wierd names. Go get 'em when needed. */
689 elfstab_offset_sections (objfile, pst)
690 struct objfile *objfile;
691 struct partial_symtab *pst;
693 char *filename = pst->filename;
694 struct dbx_symfile_info *dbx = (struct dbx_symfile_info *)
695 objfile->sym_stab_info;
696 struct stab_section_info *maybe = dbx->stab_section_info;
697 struct stab_section_info *questionable = 0;
701 /* The ELF symbol info doesn't include path names, so strip the path
702 (if any) from the psymtab filename. */
703 while (0 != (p = strchr (filename, '/')))
706 /* FIXME: This linear search could speed up significantly
707 if it was chained in the right order to match how we search it,
708 and if we unchained when we found a match. */
709 for (; maybe; maybe = maybe->next)
711 if (filename[0] == maybe->filename[0]
712 && STREQ (filename, maybe->filename))
714 /* We found a match. But there might be several source files
715 (from different directories) with the same name. */
716 if (0 == maybe->found)
718 questionable = maybe; /* Might use it later. */
722 if (maybe == 0 && questionable != 0)
724 complain (&stab_info_questionable_complaint, filename);
725 maybe = questionable;
730 /* Found it! Allocate a new psymtab struct, and fill it in. */
732 pst->section_offsets = (struct section_offsets *)
733 obstack_alloc (&objfile -> psymbol_obstack,
734 sizeof (struct section_offsets) +
735 sizeof (pst->section_offsets->offsets) * (SECT_OFF_MAX-1));
737 for (i = 0; i < SECT_OFF_MAX; i++)
738 ANOFFSET (pst->section_offsets, i) = maybe->sections[i];
742 /* We were unable to find any offsets for this file. Complain. */
743 if (dbx->stab_section_info) /* If there *is* any info, */
744 complain (&stab_info_mismatch_complaint, filename);
747 /* Register that we are able to handle ELF object file formats. */
749 static struct sym_fns elf_sym_fns =
751 bfd_target_elf_flavour,
752 elf_new_init, /* sym_new_init: init anything gbl to entire symtab */
753 elf_symfile_init, /* sym_init: read initial info, setup for sym_read() */
754 elf_symfile_read, /* sym_read: read a symbol file into symtab */
755 elf_symfile_finish, /* sym_finish: finished with file, cleanup */
756 elf_symfile_offsets, /* sym_offsets: Translate ext. to int. relocation */
757 NULL /* next: pointer to next struct sym_fns */
761 _initialize_elfread ()
763 add_symtab_fns (&elf_sym_fns);