1 /* Read ELF (Executable and Linking Format) object files for GDB.
2 Copyright 1991, 92, 93, 94, 95, 96, 1998 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., 59 Temple Place - Suite 330,
20 Boston, MA 02111-1307, USA. */
24 #include "gdb_string.h"
31 #include "stabsread.h"
32 #include "gdb-stabs.h"
33 #include "complaints.h"
36 extern void _initialize_elfread
PARAMS ((void));
38 /* The struct elfinfo is available only during ELF symbol table and
39 psymtab reading. It is destroyed at the completion of psymtab-reading.
40 It's local to elf_symfile_read. */
44 file_ptr dboffset
; /* Offset to dwarf debug section */
45 unsigned int dbsize
; /* Size of dwarf debug section */
46 file_ptr lnoffset
; /* Offset to dwarf line number section */
47 unsigned int lnsize
; /* Size of dwarf line number section */
48 asection
*stabsect
; /* Section pointer for .stab section */
49 asection
*stabindexsect
; /* Section pointer for .stab.index section */
50 asection
*mdebugsect
; /* Section pointer for .mdebug section */
53 /* Various things we might complain about... */
55 struct complaint section_info_complaint
=
56 {"elf/stab section information %s without a preceding file symbol", 0, 0};
58 struct complaint section_info_dup_complaint
=
59 {"duplicated elf/stab section information for %s", 0, 0};
61 struct complaint stab_info_mismatch_complaint
=
62 {"elf/stab section information missing for %s", 0, 0};
64 struct complaint stab_info_questionable_complaint
=
65 {"elf/stab section information questionable for %s", 0, 0};
68 elf_symfile_init
PARAMS ((struct objfile
*));
71 elf_new_init
PARAMS ((struct objfile
*));
74 elf_symfile_read
PARAMS ((struct objfile
*, int));
77 elf_symfile_finish
PARAMS ((struct objfile
*));
80 elf_symtab_read
PARAMS ((struct objfile
*, int));
83 free_elfinfo
PARAMS ((void *));
85 static struct minimal_symbol
*
86 record_minimal_symbol_and_info
PARAMS ((char *, CORE_ADDR
,
87 enum minimal_symbol_type
, char *,
88 asection
* bfd_section
,
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);
176 static struct minimal_symbol
*
177 record_minimal_symbol_and_info (name
, address
, ms_type
, info
, bfd_section
,
181 enum minimal_symbol_type ms_type
;
182 char *info
; /* FIXME, is this really char *? */
183 asection
*bfd_section
;
184 struct objfile
*objfile
;
188 /* Guess the section from the type. This is likely to be wrong in
194 section
= bfd_section
->index
;
195 #ifdef SMASH_TEXT_ADDRESS
196 SMASH_TEXT_ADDRESS (address
);
203 section
= bfd_section
->index
;
210 return prim_record_minimal_symbol_and_info
211 (name
, address
, ms_type
, info
, section
, bfd_section
, objfile
);
218 elf_symtab_read -- read the symbol table of an ELF file
222 void elf_symtab_read (struct objfile *objfile, int dynamic)
226 Given an objfile and a flag that specifies whether or not the objfile
227 is for an executable or not (may be shared library for example), add
228 all the global function and data symbols to the minimal symbol table.
230 In stabs-in-ELF, as implemented by Sun, there are some local symbols
231 defined in the ELF symbol table, which can be used to locate
232 the beginnings of sections from each ".o" file that was linked to
233 form the executable objfile. We gather any such info and record it
234 in data structures hung off the objfile's private data.
239 elf_symtab_read (objfile
, dynamic
)
240 struct objfile
*objfile
;
245 asymbol
**symbol_table
;
246 long number_of_symbols
;
249 struct cleanup
*back_to
;
252 enum minimal_symbol_type ms_type
;
253 /* If sectinfo is nonNULL, it contains section info that should end up
254 filed in the objfile. */
255 struct stab_section_info
*sectinfo
= NULL
;
256 /* If filesym is nonzero, it points to a file symbol, but we haven't
257 seen any section info for it yet. */
258 asymbol
*filesym
= 0;
259 #ifdef SOFUN_ADDRESS_MAYBE_MISSING
260 /* Name of filesym, as saved on the symbol_obstack. */
261 char *filesymname
= obsavestring ("", 0, &objfile
->symbol_obstack
);
263 struct dbx_symfile_info
*dbx
= objfile
->sym_stab_info
;
265 int stripped
= (bfd_get_symcount (objfile
->obfd
) == 0);
269 storage_needed
= bfd_get_dynamic_symtab_upper_bound (objfile
->obfd
);
271 /* Nothing to be done if there is no dynamic symtab. */
272 if (storage_needed
< 0)
277 storage_needed
= bfd_get_symtab_upper_bound (objfile
->obfd
);
278 if (storage_needed
< 0)
279 error ("Can't read symbols from %s: %s", bfd_get_filename (objfile
->obfd
),
280 bfd_errmsg (bfd_get_error ()));
282 if (storage_needed
> 0)
284 symbol_table
= (asymbol
**) xmalloc (storage_needed
);
285 back_to
= make_cleanup (free
, symbol_table
);
287 number_of_symbols
= bfd_canonicalize_dynamic_symtab (objfile
->obfd
,
290 number_of_symbols
= bfd_canonicalize_symtab (objfile
->obfd
, symbol_table
);
291 if (number_of_symbols
< 0)
292 error ("Can't read symbols from %s: %s", bfd_get_filename (objfile
->obfd
),
293 bfd_errmsg (bfd_get_error ()));
295 for (i
= 0; i
< number_of_symbols
; i
++)
297 sym
= symbol_table
[i
];
298 if (sym
->name
== NULL
|| *sym
->name
== '\0')
300 /* Skip names that don't exist (shouldn't happen), or names
301 that are null strings (may happen). */
305 offset
= ANOFFSET (objfile
->section_offsets
, sym
->section
->index
);
307 && sym
->section
== &bfd_und_section
308 && (sym
->flags
& BSF_FUNCTION
))
310 struct minimal_symbol
*msym
;
312 /* Symbol is a reference to a function defined in
314 If its value is non zero then it is usually the address
315 of the corresponding entry in the procedure linkage table,
316 plus the desired section offset.
317 If its value is zero then the dynamic linker has to resolve
318 the symbol. We are unable to find any meaningful address
319 for this symbol in the executable file, so we skip it. */
320 symaddr
= sym
->value
;
324 msym
= record_minimal_symbol_and_info
325 ((char *) sym
->name
, symaddr
,
326 mst_solib_trampoline
, NULL
, sym
->section
, objfile
);
327 #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 the section offset. */
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 addresses
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 /* If it is an Irix dynamic symbol, skip section name
397 symbols, relocate all others by section offset. */
398 if (ms_type
!= mst_abs
)
400 if (sym
->name
[0] == '.')
405 else if (sym
->section
->flags
& SEC_CODE
)
407 if (sym
->flags
& BSF_GLOBAL
)
411 else if ((sym
->name
[0] == '.' && sym
->name
[1] == 'L')
412 || ((sym
->flags
& BSF_LOCAL
)
413 && sym
->name
[0] == '$'
414 && sym
->name
[1] == 'L'))
415 /* Looks like a compiler-generated label. Skip it.
416 The assembler should be skipping these (to keep
417 executables small), but apparently with gcc on the
418 delta m88k SVR4, it loses. So to have us check too
419 should be harmless (but I encourage people to fix this
420 in the assembler instead of adding checks here). */
423 else if (sym
->name
[0] == '.' && sym
->name
[1] == '.')
425 /* Looks like a Harris compiler generated label for the
426 purpose of marking instructions that are relevant to
427 DWARF dies. The assembler can't get rid of these
428 because they are relocatable addresses that the
429 linker needs to resolve. */
435 ms_type
= mst_file_text
;
438 else if (sym
->section
->flags
& SEC_ALLOC
)
440 if (sym
->flags
& BSF_GLOBAL
)
442 if (sym
->section
->flags
& SEC_LOAD
)
451 else if (sym
->flags
& BSF_LOCAL
)
453 /* Named Local variable in a Data section. Check its
454 name for stabs-in-elf. The STREQ macro checks the
455 first character inline, so we only actually do a
456 strcmp function call on names that start with 'B'
458 index
= SECT_OFF_MAX
;
459 if (STREQ ("Bbss.bss", sym
->name
))
461 index
= SECT_OFF_BSS (objfile
);
463 else if (STREQ ("Ddata.data", sym
->name
))
465 index
= SECT_OFF_DATA (objfile
);
467 else if (STREQ ("Drodata.rodata", sym
->name
))
469 index
= SECT_OFF_RODATA (objfile
);
471 if (index
!= SECT_OFF_MAX
)
473 /* Found a special local symbol. Allocate a
474 sectinfo, if needed, and fill it in. */
475 if (sectinfo
== NULL
)
477 sectinfo
= (struct stab_section_info
*)
478 xmmalloc (objfile
->md
, sizeof (*sectinfo
));
479 memset ((PTR
) sectinfo
, 0, sizeof (*sectinfo
));
482 complain (§ion_info_complaint
,
488 (char *) filesym
->name
;
491 if (sectinfo
->sections
[index
] != 0)
493 complain (§ion_info_dup_complaint
,
496 /* Bfd symbols are section relative. */
497 symaddr
= sym
->value
+ sym
->section
->vma
;
498 /* Relocate non-absolute symbols by the section offset. */
499 if (sym
->section
!= &bfd_abs_section
)
503 sectinfo
->sections
[index
] = symaddr
;
504 /* The special local symbols don't go in the
505 minimal symbol table, so ignore this one. */
508 /* Not a special stabs-in-elf symbol, do regular
509 symbol processing. */
510 if (sym
->section
->flags
& SEC_LOAD
)
512 ms_type
= mst_file_data
;
516 ms_type
= mst_file_bss
;
521 ms_type
= mst_unknown
;
526 /* FIXME: Solaris2 shared libraries include lots of
527 odd "absolute" and "undefined" symbols, that play
528 hob with actions like finding what function the PC
529 is in. Ignore them if they aren't text, data, or bss. */
530 /* ms_type = mst_unknown; */
531 continue; /* Skip this symbol. */
533 /* Pass symbol size field in via BFD. FIXME!!! */
534 size
= ((elf_symbol_type
*) sym
)->internal_elf_sym
.st_size
;
535 msym
= record_minimal_symbol_and_info
536 ((char *) sym
->name
, symaddr
,
537 ms_type
, (PTR
) size
, sym
->section
, objfile
);
538 #ifdef SOFUN_ADDRESS_MAYBE_MISSING
540 msym
->filename
= filesymname
;
542 #ifdef ELF_MAKE_MSYMBOL_SPECIAL
543 ELF_MAKE_MSYMBOL_SPECIAL (sym
, msym
);
547 do_cleanups (back_to
);
551 /* Scan and build partial symbols for a symbol file.
552 We have been initialized by a call to elf_symfile_init, which
553 currently does nothing.
555 SECTION_OFFSETS is a set of offsets to apply to relocate the symbols
556 in each section. We simplify it down to a single offset for all
559 MAINLINE is true if we are reading the main symbol
560 table (as opposed to a shared lib or dynamically loaded file).
562 This function only does the minimum work necessary for letting the
563 user "name" things symbolically; it does not read the entire symtab.
564 Instead, it reads the external and static symbols and puts them in partial
565 symbol tables. When more extensive information is requested of a
566 file, the corresponding partial symbol table is mutated into a full
567 fledged symbol table by going back and reading the symbols
570 We look for sections with specific names, to tell us what debug
571 format to look for: FIXME!!!
573 dwarf_build_psymtabs() builds psymtabs for DWARF symbols;
574 elfstab_build_psymtabs() handles STABS symbols;
575 mdebug_build_psymtabs() handles ECOFF debugging information.
577 Note that ELF files have a "minimal" symbol table, which looks a lot
578 like a COFF symbol table, but has only the minimal information necessary
579 for linking. We process this also, and use the information to
580 build gdb's minimal symbol table. This gives us some minimal debugging
581 capability even for files compiled without -g. */
584 elf_symfile_read (objfile
, mainline
)
585 struct objfile
*objfile
;
588 bfd
*abfd
= objfile
->obfd
;
590 struct cleanup
*back_to
;
593 init_minimal_symbol_collection ();
594 back_to
= make_cleanup ((make_cleanup_func
) discard_minimal_symbols
, 0);
596 memset ((char *) &ei
, 0, sizeof (ei
));
598 /* Allocate struct to keep track of the symfile */
599 objfile
->sym_stab_info
= (struct dbx_symfile_info
*)
600 xmmalloc (objfile
->md
, sizeof (struct dbx_symfile_info
));
601 memset ((char *) objfile
->sym_stab_info
, 0, sizeof (struct dbx_symfile_info
));
602 make_cleanup (free_elfinfo
, (PTR
) objfile
);
604 /* Process the normal ELF symbol table first. This may write some
605 chain of info into the dbx_symfile_info in objfile->sym_stab_info,
606 which can later be used by elfstab_offset_sections. */
608 elf_symtab_read (objfile
, 0);
610 /* Add the dynamic symbols. */
612 elf_symtab_read (objfile
, 1);
614 /* Now process debugging information, which is contained in
615 special ELF sections. */
617 /* If we are reinitializing, or if we have never loaded syms yet,
618 set table to empty. MAINLINE is cleared so that *_read_psymtab
619 functions do not all also re-initialize the psymbol table. */
622 init_psymbol_list (objfile
, 0);
626 /* We first have to find them... */
627 bfd_map_over_sections (abfd
, elf_locate_sections
, (PTR
) & ei
);
629 /* ELF debugging information is inserted into the psymtab in the
630 order of least informative first - most informative last. Since
631 the psymtab table is searched `most recent insertion first' this
632 increases the probability that more detailed debug information
633 for a section is found.
635 For instance, an object file might contain both .mdebug (XCOFF)
636 and .debug_info (DWARF2) sections then .mdebug is inserted first
637 (searched last) and DWARF2 is inserted last (searched first). If
638 we don't do this then the XCOFF info is found first - for code in
639 an included file XCOFF info is useless. */
643 const struct ecoff_debug_swap
*swap
;
645 /* .mdebug section, presumably holding ECOFF debugging
647 swap
= get_elf_backend_data (abfd
)->elf_backend_ecoff_debug_swap
;
649 elfmdebug_build_psymtabs (objfile
, swap
, ei
.mdebugsect
);
655 /* Stab sections have an associated string table that looks like
656 a separate section. */
657 str_sect
= bfd_get_section_by_name (abfd
, ".stabstr");
659 /* FIXME should probably warn about a stab section without a stabstr. */
661 elfstab_build_psymtabs (objfile
,
663 ei
.stabsect
->filepos
,
664 bfd_section_size (abfd
, ei
.stabsect
),
666 bfd_section_size (abfd
, str_sect
));
668 if (dwarf2_has_info (abfd
))
670 /* DWARF 2 sections */
671 dwarf2_build_psymtabs (objfile
, mainline
);
673 else if (ei
.dboffset
&& ei
.lnoffset
)
676 dwarf_build_psymtabs (objfile
,
678 ei
.dboffset
, ei
.dbsize
,
679 ei
.lnoffset
, ei
.lnsize
);
682 /* Install any minimal symbols that have been collected as the current
683 minimal symbols for this objfile. */
685 install_minimal_symbols (objfile
);
687 do_cleanups (back_to
);
690 /* This cleans up the objfile's sym_stab_info pointer, and the chain of
691 stab_section_info's, that might be dangling from it. */
697 struct objfile
*objfile
= (struct objfile
*) objp
;
698 struct dbx_symfile_info
*dbxinfo
= objfile
->sym_stab_info
;
699 struct stab_section_info
*ssi
, *nssi
;
701 ssi
= dbxinfo
->stab_section_info
;
705 mfree (objfile
->md
, ssi
);
709 dbxinfo
->stab_section_info
= 0; /* Just say No mo info about this. */
713 /* Initialize anything that needs initializing when a completely new symbol
714 file is specified (not just adding some symbols from another file, e.g. a
717 We reinitialize buildsym, since we may be reading stabs from an ELF file. */
720 elf_new_init (ignore
)
721 struct objfile
*ignore
;
723 stabsread_new_init ();
724 buildsym_new_init ();
727 /* Perform any local cleanups required when we are done with a particular
728 objfile. I.E, we are in the process of discarding all symbol information
729 for an objfile, freeing up all memory held for it, and unlinking the
730 objfile struct from the global list of known objfiles. */
733 elf_symfile_finish (objfile
)
734 struct objfile
*objfile
;
736 if (objfile
->sym_stab_info
!= NULL
)
738 mfree (objfile
->md
, objfile
->sym_stab_info
);
742 /* ELF specific initialization routine for reading symbols.
744 It is passed a pointer to a struct sym_fns which contains, among other
745 things, the BFD for the file whose symbols are being read, and a slot for
746 a pointer to "private data" which we can fill with goodies.
748 For now at least, we have nothing in particular to do, so this function is
752 elf_symfile_init (objfile
)
753 struct objfile
*objfile
;
755 /* ELF objects may be reordered, so set OBJF_REORDERED. If we
756 find this causes a significant slowdown in gdb then we could
757 set it in the debug symbol readers only when necessary. */
758 objfile
->flags
|= OBJF_REORDERED
;
761 /* When handling an ELF file that contains Sun STABS debug info,
762 some of the debug info is relative to the particular chunk of the
763 section that was generated in its individual .o file. E.g.
764 offsets to static variables are relative to the start of the data
765 segment *for that module before linking*. This information is
766 painfully squirreled away in the ELF symbol table as local symbols
767 with wierd names. Go get 'em when needed. */
770 elfstab_offset_sections (objfile
, pst
)
771 struct objfile
*objfile
;
772 struct partial_symtab
*pst
;
774 char *filename
= pst
->filename
;
775 struct dbx_symfile_info
*dbx
= objfile
->sym_stab_info
;
776 struct stab_section_info
*maybe
= dbx
->stab_section_info
;
777 struct stab_section_info
*questionable
= 0;
781 /* The ELF symbol info doesn't include path names, so strip the path
782 (if any) from the psymtab filename. */
783 while (0 != (p
= strchr (filename
, '/')))
786 /* FIXME: This linear search could speed up significantly
787 if it was chained in the right order to match how we search it,
788 and if we unchained when we found a match. */
789 for (; maybe
; maybe
= maybe
->next
)
791 if (filename
[0] == maybe
->filename
[0]
792 && STREQ (filename
, maybe
->filename
))
794 /* We found a match. But there might be several source files
795 (from different directories) with the same name. */
796 if (0 == maybe
->found
)
798 questionable
= maybe
; /* Might use it later. */
802 if (maybe
== 0 && questionable
!= 0)
804 complain (&stab_info_questionable_complaint
, filename
);
805 maybe
= questionable
;
810 /* Found it! Allocate a new psymtab struct, and fill it in. */
812 pst
->section_offsets
= (struct section_offsets
*)
813 obstack_alloc (&objfile
->psymbol_obstack
, SIZEOF_SECTION_OFFSETS
);
814 for (i
= 0; i
< SECT_OFF_MAX
; i
++)
815 ANOFFSET (pst
->section_offsets
, i
) = maybe
->sections
[i
];
819 /* We were unable to find any offsets for this file. Complain. */
820 if (dbx
->stab_section_info
) /* If there *is* any info, */
821 complain (&stab_info_mismatch_complaint
, filename
);
824 /* Register that we are able to handle ELF object file formats. */
826 static struct sym_fns elf_sym_fns
=
828 bfd_target_elf_flavour
,
829 elf_new_init
, /* sym_new_init: init anything gbl to entire symtab */
830 elf_symfile_init
, /* sym_init: read initial info, setup for sym_read() */
831 elf_symfile_read
, /* sym_read: read a symbol file into symtab */
832 elf_symfile_finish
, /* sym_finish: finished with file, cleanup */
833 default_symfile_offsets
, /* sym_offsets: Translate ext. to int. relocation */
834 NULL
/* next: pointer to next struct sym_fns */
838 _initialize_elfread ()
840 add_symtab_fns (&elf_sym_fns
);