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_abs_section)
318 else if (sym -> section -> flags & SEC_CODE)
320 if (sym -> flags & BSF_GLOBAL)
324 else if (sym->name[0] == '.' && sym->name[1] == 'L')
325 /* Looks like a compiler-generated label. Skip it.
326 The assembler should be skipping these (to keep
327 executables small), but apparently with gcc on the
328 delta m88k SVR4, it loses. So to have us check too
329 should be harmless (but I encourage people to fix this
330 in the assembler instead of adding checks here). */
334 ms_type = mst_file_text;
337 else if (sym -> section -> flags & SEC_ALLOC)
339 if (sym -> flags & BSF_GLOBAL)
341 if (sym -> section -> flags & SEC_LOAD)
350 else if (sym -> flags & BSF_LOCAL)
352 /* Named Local variable in a Data section. Check its
353 name for stabs-in-elf. The STREQ macro checks the
354 first character inline, so we only actually do a
355 strcmp function call on names that start with 'B'
357 index = SECT_OFF_MAX;
358 if (STREQ ("Bbss.bss", sym -> name))
360 index = SECT_OFF_BSS;
362 else if (STREQ ("Ddata.data", sym -> name))
364 index = SECT_OFF_DATA;
366 else if (STREQ ("Drodata.rodata", sym -> name))
368 index = SECT_OFF_RODATA;
370 if (index != SECT_OFF_MAX)
372 /* Found a special local symbol. Allocate a
373 sectinfo, if needed, and fill it in. */
374 if (sectinfo == NULL)
376 sectinfo = (struct stab_section_info *)
377 xmmalloc (objfile -> md, sizeof (*sectinfo));
378 memset ((PTR) sectinfo, 0, sizeof (*sectinfo));
381 complain (§ion_info_complaint,
386 sectinfo -> filename =
387 (char *) filesym -> name;
390 if (sectinfo -> sections[index] != 0)
392 complain (§ion_info_dup_complaint,
393 sectinfo -> filename);
395 /* Bfd symbols are section relative. */
396 symaddr = sym -> value + sym -> section -> vma;
397 /* Relocate non-absolute symbols by base address. */
398 if (sym -> section != &bfd_abs_section)
402 sectinfo -> sections[index] = symaddr;
403 /* The special local symbols don't go in the
404 minimal symbol table, so ignore this one. */
407 /* Not a special stabs-in-elf symbol, do regular
408 symbol processing. */
409 if (sym -> section -> flags & SEC_LOAD)
411 ms_type = mst_file_data;
415 ms_type = mst_file_bss;
420 ms_type = mst_unknown;
425 /* FIXME: Solaris2 shared libraries include lots of
426 odd "absolute" and "undefined" symbols, that play
427 hob with actions like finding what function the PC
428 is in. Ignore them if they aren't text, data, or bss. */
429 /* ms_type = mst_unknown; */
430 continue; /* Skip this symbol. */
432 /* Pass symbol size field in via BFD. FIXME!!! */
433 size = ((elf_symbol_type *) sym) -> internal_elf_sym.st_size;
434 record_minimal_symbol_and_info ((char *) sym -> name, symaddr,
435 ms_type, (PTR) size, objfile);
438 do_cleanups (back_to);
442 /* Scan and build partial symbols for a symbol file.
443 We have been initialized by a call to elf_symfile_init, which
444 currently does nothing.
446 SECTION_OFFSETS is a set of offsets to apply to relocate the symbols
447 in each section. We simplify it down to a single offset for all
450 MAINLINE is true if we are reading the main symbol
451 table (as opposed to a shared lib or dynamically loaded file).
453 This function only does the minimum work necessary for letting the
454 user "name" things symbolically; it does not read the entire symtab.
455 Instead, it reads the external and static symbols and puts them in partial
456 symbol tables. When more extensive information is requested of a
457 file, the corresponding partial symbol table is mutated into a full
458 fledged symbol table by going back and reading the symbols
461 We look for sections with specific names, to tell us what debug
462 format to look for: FIXME!!!
464 dwarf_build_psymtabs() builds psymtabs for DWARF symbols;
465 elfstab_build_psymtabs() handles STABS symbols;
466 mdebug_build_psymtabs() handles ECOFF debugging information.
468 Note that ELF files have a "minimal" symbol table, which looks a lot
469 like a COFF symbol table, but has only the minimal information necessary
470 for linking. We process this also, and use the information to
471 build gdb's minimal symbol table. This gives us some minimal debugging
472 capability even for files compiled without -g. */
475 elf_symfile_read (objfile, section_offsets, mainline)
476 struct objfile *objfile;
477 struct section_offsets *section_offsets;
480 bfd *abfd = objfile->obfd;
482 struct cleanup *back_to;
485 init_minimal_symbol_collection ();
486 back_to = make_cleanup (discard_minimal_symbols, 0);
488 memset ((char *) &ei, 0, sizeof (ei));
490 /* Allocate struct to keep track of the symfile */
491 objfile->sym_stab_info = (PTR)
492 xmmalloc (objfile -> md, sizeof (struct dbx_symfile_info));
493 memset ((char *) objfile->sym_stab_info, 0, sizeof (struct dbx_symfile_info));
494 make_cleanup (free_elfinfo, (PTR) objfile);
496 /* Process the normal ELF symbol table first. This may write some
497 chain of info into the dbx_symfile_info in objfile->sym_stab_info,
498 which can later be used by elfstab_offset_sections. */
500 /* FIXME, should take a section_offsets param, not just an offset. */
501 offset = ANOFFSET (section_offsets, 0);
502 elf_symtab_read (abfd, offset, objfile);
504 /* Now process debugging information, which is contained in
505 special ELF sections. We first have to find them... */
507 bfd_map_over_sections (abfd, elf_locate_sections, (PTR) &ei);
508 if (ei.dboffset && ei.lnoffset)
511 dwarf_build_psymtabs (objfile,
512 section_offsets, mainline,
513 ei.dboffset, ei.dbsize,
514 ei.lnoffset, ei.lnsize);
520 /* FIXME: Sun didn't really know how to implement this well.
521 They made .stab sections that don't point to the .stabstr
522 section with the sh_link field. BFD doesn't make string table
523 sections visible to the caller. So we have to search the
524 ELF section table, not the BFD section table, for the string
526 struct elf32_internal_shdr *elf_sect;
528 elf_sect = bfd_elf_find_section (abfd, ".stabstr");
530 elfstab_build_psymtabs (objfile,
533 ei.stabsect->filepos, /* .stab offset */
534 bfd_get_section_size_before_reloc (ei.stabsect),/* .stab size */
535 (file_ptr) elf_sect->sh_offset, /* .stabstr offset */
536 elf_sect->sh_size); /* .stabstr size */
540 const struct ecoff_debug_swap *swap;
542 /* .mdebug section, presumably holding ECOFF debugging
544 swap = get_elf_backend_data (abfd)->elf_backend_ecoff_debug_swap;
546 elfmdebug_build_psymtabs (objfile, swap, ei.mdebugsect,
550 if (!have_partial_symbols ())
553 printf_filtered ("(no debugging symbols found)...");
557 /* Install any minimal symbols that have been collected as the current
558 minimal symbols for this objfile. */
560 install_minimal_symbols (objfile);
562 do_cleanups (back_to);
565 /* This cleans up the objfile's sym_stab_info pointer, and the chain of
566 stab_section_info's, that might be dangling from it. */
572 struct objfile *objfile = (struct objfile *)objp;
573 struct dbx_symfile_info *dbxinfo = (struct dbx_symfile_info *)
574 objfile->sym_stab_info;
575 struct stab_section_info *ssi, *nssi;
577 ssi = dbxinfo->stab_section_info;
581 mfree (objfile->md, ssi);
585 dbxinfo->stab_section_info = 0; /* Just say No mo info about this. */
589 /* Initialize anything that needs initializing when a completely new symbol
590 file is specified (not just adding some symbols from another file, e.g. a
593 We reinitialize buildsym, since we may be reading stabs from an ELF file. */
596 elf_new_init (ignore)
597 struct objfile *ignore;
599 stabsread_new_init ();
600 buildsym_new_init ();
603 /* Perform any local cleanups required when we are done with a particular
604 objfile. I.E, we are in the process of discarding all symbol information
605 for an objfile, freeing up all memory held for it, and unlinking the
606 objfile struct from the global list of known objfiles. */
609 elf_symfile_finish (objfile)
610 struct objfile *objfile;
612 if (objfile -> sym_stab_info != NULL)
614 mfree (objfile -> md, objfile -> sym_stab_info);
618 /* ELF specific initialization routine for reading symbols.
620 It is passed a pointer to a struct sym_fns which contains, among other
621 things, the BFD for the file whose symbols are being read, and a slot for
622 a pointer to "private data" which we can fill with goodies.
624 For now at least, we have nothing in particular to do, so this function is
628 elf_symfile_init (ignore)
629 struct objfile *ignore;
633 /* ELF specific parsing routine for section offsets.
635 Plain and simple for now. */
638 struct section_offsets *
639 elf_symfile_offsets (objfile, addr)
640 struct objfile *objfile;
643 struct section_offsets *section_offsets;
646 objfile->num_sections = SECT_OFF_MAX;
647 section_offsets = (struct section_offsets *)
648 obstack_alloc (&objfile -> psymbol_obstack,
649 sizeof (struct section_offsets)
650 + sizeof (section_offsets->offsets) * (SECT_OFF_MAX-1));
652 for (i = 0; i < SECT_OFF_MAX; i++)
653 ANOFFSET (section_offsets, i) = addr;
655 return section_offsets;
658 /* When handling an ELF file that contains Sun STABS debug info,
659 some of the debug info is relative to the particular chunk of the
660 section that was generated in its individual .o file. E.g.
661 offsets to static variables are relative to the start of the data
662 segment *for that module before linking*. This information is
663 painfully squirreled away in the ELF symbol table as local symbols
664 with wierd names. Go get 'em when needed. */
667 elfstab_offset_sections (objfile, pst)
668 struct objfile *objfile;
669 struct partial_symtab *pst;
671 char *filename = pst->filename;
672 struct dbx_symfile_info *dbx = (struct dbx_symfile_info *)
673 objfile->sym_stab_info;
674 struct stab_section_info *maybe = dbx->stab_section_info;
675 struct stab_section_info *questionable = 0;
679 /* The ELF symbol info doesn't include path names, so strip the path
680 (if any) from the psymtab filename. */
681 while (0 != (p = strchr (filename, '/')))
684 /* FIXME: This linear search could speed up significantly
685 if it was chained in the right order to match how we search it,
686 and if we unchained when we found a match. */
687 for (; maybe; maybe = maybe->next)
689 if (filename[0] == maybe->filename[0]
690 && STREQ (filename, maybe->filename))
692 /* We found a match. But there might be several source files
693 (from different directories) with the same name. */
694 if (0 == maybe->found)
696 questionable = maybe; /* Might use it later. */
700 if (maybe == 0 && questionable != 0)
702 complain (&stab_info_questionable_complaint, filename);
703 maybe = questionable;
708 /* Found it! Allocate a new psymtab struct, and fill it in. */
710 pst->section_offsets = (struct section_offsets *)
711 obstack_alloc (&objfile -> psymbol_obstack,
712 sizeof (struct section_offsets) +
713 sizeof (pst->section_offsets->offsets) * (SECT_OFF_MAX-1));
715 for (i = 0; i < SECT_OFF_MAX; i++)
716 ANOFFSET (pst->section_offsets, i) = maybe->sections[i];
720 /* We were unable to find any offsets for this file. Complain. */
721 if (dbx->stab_section_info) /* If there *is* any info, */
722 complain (&stab_info_mismatch_complaint, filename);
725 /* Register that we are able to handle ELF object file formats. */
727 static struct sym_fns elf_sym_fns =
729 bfd_target_elf_flavour,
730 elf_new_init, /* sym_new_init: init anything gbl to entire symtab */
731 elf_symfile_init, /* sym_init: read initial info, setup for sym_read() */
732 elf_symfile_read, /* sym_read: read a symbol file into symtab */
733 elf_symfile_finish, /* sym_finish: finished with file, cleanup */
734 elf_symfile_offsets, /* sym_offsets: Translate ext. to int. relocation */
735 NULL /* next: pointer to next struct sym_fns */
739 _initialize_elfread ()
741 add_symtab_fns (&elf_sym_fns);