1 /* Read ELF (Executable and Linking Format) object files for GDB.
2 Copyright 1991, 1992, 1993, 1994, 1995 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. */
30 #include "stabsread.h"
31 #include "gdb-stabs.h"
32 #include "complaints.h"
35 /* The struct elfinfo is available only during ELF symbol table and
36 psymtab reading. It is destroyed at the complation of psymtab-reading.
37 It's local to elf_symfile_read. */
40 file_ptr dboffset
; /* Offset to dwarf debug section */
41 unsigned int dbsize
; /* Size of dwarf debug section */
42 file_ptr lnoffset
; /* Offset to dwarf line number section */
43 unsigned int lnsize
; /* Size of dwarf line number section */
44 asection
*stabsect
; /* Section pointer for .stab section */
45 asection
*stabindexsect
; /* Section pointer for .stab.index section */
46 asection
*mdebugsect
; /* Section pointer for .mdebug section */
49 /* Various things we might complain about... */
51 struct complaint section_info_complaint
=
52 {"elf/stab section information %s without a preceding file symbol", 0, 0};
54 struct complaint section_info_dup_complaint
=
55 {"duplicated elf/stab section information for %s", 0, 0};
57 struct complaint stab_info_mismatch_complaint
=
58 {"elf/stab section information missing for %s", 0, 0};
60 struct complaint stab_info_questionable_complaint
=
61 {"elf/stab section information questionable for %s", 0, 0};
64 elf_symfile_init
PARAMS ((struct objfile
*));
67 elf_new_init
PARAMS ((struct objfile
*));
70 elf_symfile_read
PARAMS ((struct objfile
*, struct section_offsets
*, int));
73 elf_symfile_finish
PARAMS ((struct objfile
*));
76 elf_symtab_read
PARAMS ((bfd
*, CORE_ADDR
, struct objfile
*, int));
79 free_elfinfo
PARAMS ((void *));
81 static struct section_offsets
*
82 elf_symfile_offsets
PARAMS ((struct objfile
*, CORE_ADDR
));
84 static struct minimal_symbol
*
85 record_minimal_symbol_and_info
PARAMS ((char *, CORE_ADDR
,
86 enum minimal_symbol_type
, char *,
90 elf_locate_sections
PARAMS ((bfd
*, asection
*, void *));
92 /* We are called once per section from elf_symfile_read. We
93 need to examine each section we are passed, check to see
94 if it is something we are interested in processing, and
95 if so, stash away some access information for the section.
97 For now we recognize the dwarf debug information sections and
98 line number sections from matching their section names. The
99 ELF definition is no real help here since it has no direct
100 knowledge of DWARF (by design, so any debugging format can be
103 We also recognize the ".stab" sections used by the Sun compilers
104 released with Solaris 2.
106 FIXME: The section names should not be hardwired strings (what
107 should they be? I don't think most object file formats have enough
108 section flags to specify what kind of debug section it is
112 elf_locate_sections (ignore_abfd
, sectp
, eip
)
117 register struct elfinfo
*ei
;
119 ei
= (struct elfinfo
*) eip
;
120 if (STREQ (sectp
-> name
, ".debug"))
122 ei
-> dboffset
= sectp
-> filepos
;
123 ei
-> dbsize
= bfd_get_section_size_before_reloc (sectp
);
125 else if (STREQ (sectp
-> name
, ".line"))
127 ei
-> lnoffset
= sectp
-> filepos
;
128 ei
-> lnsize
= bfd_get_section_size_before_reloc (sectp
);
130 else if (STREQ (sectp
-> name
, ".stab"))
132 ei
-> stabsect
= sectp
;
134 else if (STREQ (sectp
-> name
, ".stab.index"))
136 ei
-> stabindexsect
= sectp
;
138 else if (STREQ (sectp
-> name
, ".mdebug"))
140 ei
-> mdebugsect
= sectp
;
144 #if 0 /* Currently unused */
147 elf_interpreter (abfd
)
154 interp_sec
= bfd_get_section_by_name (abfd
, ".interp");
157 size
= bfd_section_size (abfd
, interp_sec
);
158 interp
= alloca (size
);
159 if (bfd_get_section_contents (abfd
, interp_sec
, interp
, (file_ptr
)0,
162 interp
= savestring (interp
, size
- 1);
174 static struct minimal_symbol
*
175 record_minimal_symbol_and_info (name
, address
, ms_type
, info
, objfile
)
178 enum minimal_symbol_type ms_type
;
179 char *info
; /* FIXME, is this really char *? */
180 struct objfile
*objfile
;
184 /* Guess the section from the type. This is likely to be wrong in
190 section
= SECT_OFF_TEXT
;
191 #ifdef SMASH_TEXT_ADDRESS
192 SMASH_TEXT_ADDRESS (address
);
197 section
= SECT_OFF_DATA
;
201 section
= SECT_OFF_BSS
;
208 name
= obsavestring (name
, strlen (name
), &objfile
-> symbol_obstack
);
209 return prim_record_minimal_symbol_and_info
210 (name
, address
, ms_type
, info
, section
, objfile
);
217 elf_symtab_read -- read the symbol table of an ELF file
221 void elf_symtab_read (bfd *abfd, CORE_ADDR addr,
222 struct objfile *objfile, int dynamic)
226 Given an open bfd, a base address to relocate symbols to, and a
227 flag that specifies whether or not this bfd is for an executable
228 or not (may be shared library for example), add all the global
229 function and data symbols to the minimal symbol table.
231 In stabs-in-ELF, as implemented by Sun, there are some local symbols
232 defined in the ELF symbol table, which can be used to locate
233 the beginnings of sections from each ".o" file that was linked to
234 form the executable objfile. We gather any such info and record it
235 in data structures hung off the objfile's private data.
240 elf_symtab_read (abfd
, addr
, objfile
, dynamic
)
243 struct objfile
*objfile
;
248 asymbol
**symbol_table
;
249 long number_of_symbols
;
252 struct cleanup
*back_to
;
254 enum minimal_symbol_type ms_type
;
255 /* If sectinfo is nonNULL, it contains section info that should end up
256 filed in the objfile. */
257 struct stab_section_info
*sectinfo
= NULL
;
258 /* If filesym is nonzero, it points to a file symbol, but we haven't
259 seen any section info for it yet. */
260 asymbol
*filesym
= 0;
261 #ifdef SOFUN_ADDRESS_MAYBE_MISSING
262 /* Name of filesym, as saved on the symbol_obstack. */
263 char *filesymname
= obsavestring ("", 0, &objfile
->symbol_obstack
);
265 struct dbx_symfile_info
*dbx
= (struct dbx_symfile_info
*)
266 objfile
->sym_stab_info
;
268 int stripped
= (bfd_get_symcount (abfd
) == 0);
272 storage_needed
= bfd_get_dynamic_symtab_upper_bound (abfd
);
274 /* Nothing to be done if there is no dynamic symtab. */
275 if (storage_needed
< 0)
280 storage_needed
= bfd_get_symtab_upper_bound (abfd
);
281 if (storage_needed
< 0)
282 error ("Can't read symbols from %s: %s", bfd_get_filename (abfd
),
283 bfd_errmsg (bfd_get_error ()));
285 if (storage_needed
> 0)
287 symbol_table
= (asymbol
**) xmalloc (storage_needed
);
288 back_to
= make_cleanup (free
, symbol_table
);
290 number_of_symbols
= bfd_canonicalize_dynamic_symtab (abfd
,
293 number_of_symbols
= bfd_canonicalize_symtab (abfd
, symbol_table
);
294 if (number_of_symbols
< 0)
295 error ("Can't read symbols from %s: %s", bfd_get_filename (abfd
),
296 bfd_errmsg (bfd_get_error ()));
297 for (i
= 0; i
< number_of_symbols
; i
++)
299 sym
= symbol_table
[i
];
300 if (sym
-> name
== NULL
|| *sym
-> name
== '\0')
302 /* Skip names that don't exist (shouldn't happen), or names
303 that are null strings (may happen). */
308 && sym
-> section
== &bfd_und_section
309 && (sym
-> flags
& BSF_FUNCTION
))
311 struct minimal_symbol
*msym
;
313 /* Symbol is a reference to a function defined in
315 If its value is non zero then it is usually the address
316 of the corresponding entry in the procedure linkage table,
317 relative to the base address.
318 If its value is zero then the dynamic linker has to resolve
319 the symbol. We are unable to find any meaningful address
320 for this symbol in the executable file, so we skip it. */
321 symaddr
= sym
-> value
;
325 msym
= record_minimal_symbol_and_info
326 ((char *) sym
-> name
, symaddr
,
327 mst_solib_trampoline
, NULL
, objfile
);
328 #ifdef SOFUN_ADDRESS_MAYBE_MISSING
329 msym
->filename
= filesymname
;
334 /* If it is a nonstripped executable, do not enter dynamic
335 symbols, as the dynamic symbol table is usually a subset
336 of the main symbol table. */
337 if (dynamic
&& !stripped
)
339 if (sym
-> flags
& BSF_FILE
)
341 /* STT_FILE debugging symbol that helps stabs-in-elf debugging.
342 Chain any old one onto the objfile; remember new sym. */
343 if (sectinfo
!= NULL
)
345 sectinfo
-> next
= dbx
-> stab_section_info
;
346 dbx
-> stab_section_info
= sectinfo
;
350 #ifdef SOFUN_ADDRESS_MAYBE_MISSING
352 obsavestring ((char *)filesym
->name
, strlen (filesym
->name
),
353 &objfile
->symbol_obstack
);
356 else if (sym
-> flags
& (BSF_GLOBAL
| BSF_LOCAL
| BSF_WEAK
))
358 struct minimal_symbol
*msym
;
360 /* Select global/local/weak symbols. Note that bfd puts abs
361 symbols in their own section, so all symbols we are
362 interested in will have a section. */
363 /* Bfd symbols are section relative. */
364 symaddr
= sym
-> value
+ sym
-> section
-> vma
;
365 /* Relocate all non-absolute symbols by base address. */
366 if (sym
-> section
!= &bfd_abs_section
)
370 /* For non-absolute symbols, use the type of the section
371 they are relative to, to intuit text/data. Bfd provides
372 no way of figuring this out for absolute symbols. */
373 if (sym
-> section
== &bfd_abs_section
)
375 /* This is a hack to get the minimal symbol type
376 right for Irix 5, which has absolute adresses
377 with special section indices for dynamic symbols. */
378 unsigned short shndx
=
379 ((elf_symbol_type
*) sym
)->internal_elf_sym
.st_shndx
;
389 case SHN_MIPS_ACOMMON
:
396 else if (sym
-> section
-> flags
& SEC_CODE
)
398 if (sym
-> flags
& BSF_GLOBAL
)
402 else if ((sym
->name
[0] == '.' && sym
->name
[1] == 'L')
403 || ((sym
-> flags
& BSF_LOCAL
)
404 && sym
->name
[0] == '$'
405 && sym
->name
[1] == 'L'))
406 /* Looks like a compiler-generated label. Skip it.
407 The assembler should be skipping these (to keep
408 executables small), but apparently with gcc on the
409 delta m88k SVR4, it loses. So to have us check too
410 should be harmless (but I encourage people to fix this
411 in the assembler instead of adding checks here). */
415 ms_type
= mst_file_text
;
418 else if (sym
-> section
-> flags
& SEC_ALLOC
)
420 if (sym
-> flags
& BSF_GLOBAL
)
422 if (sym
-> section
-> flags
& SEC_LOAD
)
431 else if (sym
-> flags
& BSF_LOCAL
)
433 /* Named Local variable in a Data section. Check its
434 name for stabs-in-elf. The STREQ macro checks the
435 first character inline, so we only actually do a
436 strcmp function call on names that start with 'B'
438 index
= SECT_OFF_MAX
;
439 if (STREQ ("Bbss.bss", sym
-> name
))
441 index
= SECT_OFF_BSS
;
443 else if (STREQ ("Ddata.data", sym
-> name
))
445 index
= SECT_OFF_DATA
;
447 else if (STREQ ("Drodata.rodata", sym
-> name
))
449 index
= SECT_OFF_RODATA
;
451 if (index
!= SECT_OFF_MAX
)
453 /* Found a special local symbol. Allocate a
454 sectinfo, if needed, and fill it in. */
455 if (sectinfo
== NULL
)
457 sectinfo
= (struct stab_section_info
*)
458 xmmalloc (objfile
-> md
, sizeof (*sectinfo
));
459 memset ((PTR
) sectinfo
, 0, sizeof (*sectinfo
));
462 complain (§ion_info_complaint
,
467 sectinfo
-> filename
=
468 (char *) filesym
-> name
;
471 if (sectinfo
-> sections
[index
] != 0)
473 complain (§ion_info_dup_complaint
,
474 sectinfo
-> filename
);
476 /* Bfd symbols are section relative. */
477 symaddr
= sym
-> value
+ sym
-> section
-> vma
;
478 /* Relocate non-absolute symbols by base address. */
479 if (sym
-> section
!= &bfd_abs_section
)
483 sectinfo
-> sections
[index
] = symaddr
;
484 /* The special local symbols don't go in the
485 minimal symbol table, so ignore this one. */
488 /* Not a special stabs-in-elf symbol, do regular
489 symbol processing. */
490 if (sym
-> section
-> flags
& SEC_LOAD
)
492 ms_type
= mst_file_data
;
496 ms_type
= mst_file_bss
;
501 ms_type
= mst_unknown
;
506 /* FIXME: Solaris2 shared libraries include lots of
507 odd "absolute" and "undefined" symbols, that play
508 hob with actions like finding what function the PC
509 is in. Ignore them if they aren't text, data, or bss. */
510 /* ms_type = mst_unknown; */
511 continue; /* Skip this symbol. */
513 /* Pass symbol size field in via BFD. FIXME!!! */
514 size
= ((elf_symbol_type
*) sym
) -> internal_elf_sym
.st_size
;
515 msym
= record_minimal_symbol_and_info
516 ((char *) sym
-> name
, symaddr
,
517 ms_type
, (PTR
) size
, objfile
);
518 #ifdef SOFUN_ADDRESS_MAYBE_MISSING
519 msym
->filename
= filesymname
;
523 do_cleanups (back_to
);
527 /* Scan and build partial symbols for a symbol file.
528 We have been initialized by a call to elf_symfile_init, which
529 currently does nothing.
531 SECTION_OFFSETS is a set of offsets to apply to relocate the symbols
532 in each section. We simplify it down to a single offset for all
535 MAINLINE is true if we are reading the main symbol
536 table (as opposed to a shared lib or dynamically loaded file).
538 This function only does the minimum work necessary for letting the
539 user "name" things symbolically; it does not read the entire symtab.
540 Instead, it reads the external and static symbols and puts them in partial
541 symbol tables. When more extensive information is requested of a
542 file, the corresponding partial symbol table is mutated into a full
543 fledged symbol table by going back and reading the symbols
546 We look for sections with specific names, to tell us what debug
547 format to look for: FIXME!!!
549 dwarf_build_psymtabs() builds psymtabs for DWARF symbols;
550 elfstab_build_psymtabs() handles STABS symbols;
551 mdebug_build_psymtabs() handles ECOFF debugging information.
553 Note that ELF files have a "minimal" symbol table, which looks a lot
554 like a COFF symbol table, but has only the minimal information necessary
555 for linking. We process this also, and use the information to
556 build gdb's minimal symbol table. This gives us some minimal debugging
557 capability even for files compiled without -g. */
560 elf_symfile_read (objfile
, section_offsets
, mainline
)
561 struct objfile
*objfile
;
562 struct section_offsets
*section_offsets
;
565 bfd
*abfd
= objfile
->obfd
;
567 struct cleanup
*back_to
;
570 init_minimal_symbol_collection ();
571 back_to
= make_cleanup (discard_minimal_symbols
, 0);
573 memset ((char *) &ei
, 0, sizeof (ei
));
575 /* Allocate struct to keep track of the symfile */
576 objfile
->sym_stab_info
= (PTR
)
577 xmmalloc (objfile
-> md
, sizeof (struct dbx_symfile_info
));
578 memset ((char *) objfile
->sym_stab_info
, 0, sizeof (struct dbx_symfile_info
));
579 make_cleanup (free_elfinfo
, (PTR
) objfile
);
581 /* Process the normal ELF symbol table first. This may write some
582 chain of info into the dbx_symfile_info in objfile->sym_stab_info,
583 which can later be used by elfstab_offset_sections. */
585 /* FIXME, should take a section_offsets param, not just an offset. */
586 offset
= ANOFFSET (section_offsets
, 0);
587 elf_symtab_read (abfd
, offset
, objfile
, 0);
589 /* Add the dynamic symbols. */
591 elf_symtab_read (abfd
, offset
, objfile
, 1);
593 /* Now process debugging information, which is contained in
594 special ELF sections. We first have to find them... */
596 bfd_map_over_sections (abfd
, elf_locate_sections
, (PTR
) &ei
);
597 if (ei
.dboffset
&& ei
.lnoffset
)
600 dwarf_build_psymtabs (objfile
,
601 section_offsets
, mainline
,
602 ei
.dboffset
, ei
.dbsize
,
603 ei
.lnoffset
, ei
.lnsize
);
609 /* Stab sections have an associated string table that looks like
610 a separate section. */
611 str_sect
= bfd_get_section_by_name (abfd
, ".stabstr");
613 /* FIXME should probably warn about a stab section without a stabstr. */
615 elfstab_build_psymtabs (objfile
,
618 ei
.stabsect
->filepos
,
619 bfd_section_size (abfd
, ei
.stabsect
),
621 bfd_section_size (abfd
, str_sect
));
625 const struct ecoff_debug_swap
*swap
;
627 /* .mdebug section, presumably holding ECOFF debugging
629 swap
= get_elf_backend_data (abfd
)->elf_backend_ecoff_debug_swap
;
631 elfmdebug_build_psymtabs (objfile
, swap
, ei
.mdebugsect
,
635 /* Install any minimal symbols that have been collected as the current
636 minimal symbols for this objfile. */
638 install_minimal_symbols (objfile
);
640 do_cleanups (back_to
);
643 /* This cleans up the objfile's sym_stab_info pointer, and the chain of
644 stab_section_info's, that might be dangling from it. */
650 struct objfile
*objfile
= (struct objfile
*)objp
;
651 struct dbx_symfile_info
*dbxinfo
= (struct dbx_symfile_info
*)
652 objfile
->sym_stab_info
;
653 struct stab_section_info
*ssi
, *nssi
;
655 ssi
= dbxinfo
->stab_section_info
;
659 mfree (objfile
->md
, ssi
);
663 dbxinfo
->stab_section_info
= 0; /* Just say No mo info about this. */
667 /* Initialize anything that needs initializing when a completely new symbol
668 file is specified (not just adding some symbols from another file, e.g. a
671 We reinitialize buildsym, since we may be reading stabs from an ELF file. */
674 elf_new_init (ignore
)
675 struct objfile
*ignore
;
677 stabsread_new_init ();
678 buildsym_new_init ();
681 /* Perform any local cleanups required when we are done with a particular
682 objfile. I.E, we are in the process of discarding all symbol information
683 for an objfile, freeing up all memory held for it, and unlinking the
684 objfile struct from the global list of known objfiles. */
687 elf_symfile_finish (objfile
)
688 struct objfile
*objfile
;
690 if (objfile
-> sym_stab_info
!= NULL
)
692 mfree (objfile
-> md
, objfile
-> sym_stab_info
);
696 /* ELF specific initialization routine for reading symbols.
698 It is passed a pointer to a struct sym_fns which contains, among other
699 things, the BFD for the file whose symbols are being read, and a slot for
700 a pointer to "private data" which we can fill with goodies.
702 For now at least, we have nothing in particular to do, so this function is
706 elf_symfile_init (ignore
)
707 struct objfile
*ignore
;
711 /* ELF specific parsing routine for section offsets.
713 Plain and simple for now. */
716 struct section_offsets
*
717 elf_symfile_offsets (objfile
, addr
)
718 struct objfile
*objfile
;
721 struct section_offsets
*section_offsets
;
724 objfile
->num_sections
= SECT_OFF_MAX
;
725 section_offsets
= (struct section_offsets
*)
726 obstack_alloc (&objfile
-> psymbol_obstack
,
727 sizeof (struct section_offsets
)
728 + sizeof (section_offsets
->offsets
) * (SECT_OFF_MAX
-1));
730 for (i
= 0; i
< SECT_OFF_MAX
; i
++)
731 ANOFFSET (section_offsets
, i
) = addr
;
733 return section_offsets
;
736 /* When handling an ELF file that contains Sun STABS debug info,
737 some of the debug info is relative to the particular chunk of the
738 section that was generated in its individual .o file. E.g.
739 offsets to static variables are relative to the start of the data
740 segment *for that module before linking*. This information is
741 painfully squirreled away in the ELF symbol table as local symbols
742 with wierd names. Go get 'em when needed. */
745 elfstab_offset_sections (objfile
, pst
)
746 struct objfile
*objfile
;
747 struct partial_symtab
*pst
;
749 char *filename
= pst
->filename
;
750 struct dbx_symfile_info
*dbx
= (struct dbx_symfile_info
*)
751 objfile
->sym_stab_info
;
752 struct stab_section_info
*maybe
= dbx
->stab_section_info
;
753 struct stab_section_info
*questionable
= 0;
757 /* The ELF symbol info doesn't include path names, so strip the path
758 (if any) from the psymtab filename. */
759 while (0 != (p
= strchr (filename
, '/')))
762 /* FIXME: This linear search could speed up significantly
763 if it was chained in the right order to match how we search it,
764 and if we unchained when we found a match. */
765 for (; maybe
; maybe
= maybe
->next
)
767 if (filename
[0] == maybe
->filename
[0]
768 && STREQ (filename
, maybe
->filename
))
770 /* We found a match. But there might be several source files
771 (from different directories) with the same name. */
772 if (0 == maybe
->found
)
774 questionable
= maybe
; /* Might use it later. */
778 if (maybe
== 0 && questionable
!= 0)
780 complain (&stab_info_questionable_complaint
, filename
);
781 maybe
= questionable
;
786 /* Found it! Allocate a new psymtab struct, and fill it in. */
788 pst
->section_offsets
= (struct section_offsets
*)
789 obstack_alloc (&objfile
-> psymbol_obstack
,
790 sizeof (struct section_offsets
) +
791 sizeof (pst
->section_offsets
->offsets
) * (SECT_OFF_MAX
-1));
793 for (i
= 0; i
< SECT_OFF_MAX
; i
++)
794 ANOFFSET (pst
->section_offsets
, i
) = maybe
->sections
[i
];
798 /* We were unable to find any offsets for this file. Complain. */
799 if (dbx
->stab_section_info
) /* If there *is* any info, */
800 complain (&stab_info_mismatch_complaint
, filename
);
803 /* Register that we are able to handle ELF object file formats. */
805 static struct sym_fns elf_sym_fns
=
807 bfd_target_elf_flavour
,
808 elf_new_init
, /* sym_new_init: init anything gbl to entire symtab */
809 elf_symfile_init
, /* sym_init: read initial info, setup for sym_read() */
810 elf_symfile_read
, /* sym_read: read a symbol file into symtab */
811 elf_symfile_finish
, /* sym_finish: finished with file, cleanup */
812 elf_symfile_offsets
, /* sym_offsets: Translate ext. to int. relocation */
813 NULL
/* next: pointer to next struct sym_fns */
817 _initialize_elfread ()
819 add_symtab_fns (&elf_sym_fns
);