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 complation 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 ((bfd
*, CORE_ADDR
, 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
= SECT_OFF_TEXT
;
195 #ifdef SMASH_TEXT_ADDRESS
196 SMASH_TEXT_ADDRESS (address
);
201 section
= SECT_OFF_DATA
;
205 section
= SECT_OFF_BSS
;
212 return prim_record_minimal_symbol_and_info
213 (name
, address
, ms_type
, info
, section
, bfd_section
, objfile
);
220 elf_symtab_read -- read the symbol table of an ELF file
224 void elf_symtab_read (bfd *abfd, CORE_ADDR addr,
225 struct objfile *objfile, int dynamic)
229 Given an open bfd, a base address to relocate symbols to, and a
230 flag that specifies whether or not this bfd is for an executable
231 or not (may be shared library for example), add all the global
232 function and data symbols to the minimal symbol table.
234 In stabs-in-ELF, as implemented by Sun, there are some local symbols
235 defined in the ELF symbol table, which can be used to locate
236 the beginnings of sections from each ".o" file that was linked to
237 form the executable objfile. We gather any such info and record it
238 in data structures hung off the objfile's private data.
243 elf_symtab_read (abfd
, addr
, objfile
, dynamic
)
246 struct objfile
*objfile
;
251 asymbol
**symbol_table
;
252 long number_of_symbols
;
255 struct cleanup
*back_to
;
257 enum minimal_symbol_type ms_type
;
258 /* If sectinfo is nonNULL, it contains section info that should end up
259 filed in the objfile. */
260 struct stab_section_info
*sectinfo
= NULL
;
261 /* If filesym is nonzero, it points to a file symbol, but we haven't
262 seen any section info for it yet. */
263 asymbol
*filesym
= 0;
264 #ifdef SOFUN_ADDRESS_MAYBE_MISSING
265 /* Name of filesym, as saved on the symbol_obstack. */
266 char *filesymname
= obsavestring ("", 0, &objfile
->symbol_obstack
);
268 struct dbx_symfile_info
*dbx
= objfile
->sym_stab_info
;
270 int stripped
= (bfd_get_symcount (abfd
) == 0);
274 storage_needed
= bfd_get_dynamic_symtab_upper_bound (abfd
);
276 /* Nothing to be done if there is no dynamic symtab. */
277 if (storage_needed
< 0)
282 storage_needed
= bfd_get_symtab_upper_bound (abfd
);
283 if (storage_needed
< 0)
284 error ("Can't read symbols from %s: %s", bfd_get_filename (abfd
),
285 bfd_errmsg (bfd_get_error ()));
287 if (storage_needed
> 0)
289 symbol_table
= (asymbol
**) xmalloc (storage_needed
);
290 back_to
= make_cleanup (free
, symbol_table
);
292 number_of_symbols
= bfd_canonicalize_dynamic_symtab (abfd
,
295 number_of_symbols
= bfd_canonicalize_symtab (abfd
, symbol_table
);
296 if (number_of_symbols
< 0)
297 error ("Can't read symbols from %s: %s", bfd_get_filename (abfd
),
298 bfd_errmsg (bfd_get_error ()));
299 for (i
= 0; i
< number_of_symbols
; i
++)
301 sym
= symbol_table
[i
];
302 if (sym
->name
== NULL
|| *sym
->name
== '\0')
304 /* Skip names that don't exist (shouldn't happen), or names
305 that are null strings (may happen). */
310 && sym
->section
== &bfd_und_section
311 && (sym
->flags
& BSF_FUNCTION
))
313 struct minimal_symbol
*msym
;
315 /* Symbol is a reference to a function defined in
317 If its value is non zero then it is usually the address
318 of the corresponding entry in the procedure linkage table,
319 relative to the base address.
320 If its value is zero then the dynamic linker has to resolve
321 the symbol. We are unable to find any meaningful address
322 for this symbol in the executable file, so we skip it. */
323 symaddr
= sym
->value
;
327 msym
= record_minimal_symbol_and_info
328 ((char *) sym
->name
, symaddr
,
329 mst_solib_trampoline
, NULL
, sym
->section
, objfile
);
330 #ifdef SOFUN_ADDRESS_MAYBE_MISSING
332 msym
->filename
= filesymname
;
337 /* If it is a nonstripped executable, do not enter dynamic
338 symbols, as the dynamic symbol table is usually a subset
339 of the main symbol table. */
340 if (dynamic
&& !stripped
)
342 if (sym
->flags
& BSF_FILE
)
344 /* STT_FILE debugging symbol that helps stabs-in-elf debugging.
345 Chain any old one onto the objfile; remember new sym. */
346 if (sectinfo
!= NULL
)
348 sectinfo
->next
= dbx
->stab_section_info
;
349 dbx
->stab_section_info
= sectinfo
;
353 #ifdef SOFUN_ADDRESS_MAYBE_MISSING
355 obsavestring ((char *) filesym
->name
, strlen (filesym
->name
),
356 &objfile
->symbol_obstack
);
359 else if (sym
->flags
& (BSF_GLOBAL
| BSF_LOCAL
| BSF_WEAK
))
361 struct minimal_symbol
*msym
;
363 /* Select global/local/weak symbols. Note that bfd puts abs
364 symbols in their own section, so all symbols we are
365 interested in will have a section. */
366 /* Bfd symbols are section relative. */
367 symaddr
= sym
->value
+ sym
->section
->vma
;
368 /* Relocate all non-absolute symbols by base address. */
369 if (sym
->section
!= &bfd_abs_section
)
373 /* For non-absolute symbols, use the type of the section
374 they are relative to, to intuit text/data. Bfd provides
375 no way of figuring this out for absolute symbols. */
376 if (sym
->section
== &bfd_abs_section
)
378 /* This is a hack to get the minimal symbol type
379 right for Irix 5, which has absolute adresses
380 with special section indices for dynamic symbols. */
381 unsigned short shndx
=
382 ((elf_symbol_type
*) sym
)->internal_elf_sym
.st_shndx
;
392 case SHN_MIPS_ACOMMON
:
399 /* If it is an Irix dynamic symbol, skip section name
400 symbols, relocate all others. */
401 if (ms_type
!= mst_abs
)
403 if (sym
->name
[0] == '.')
408 else if (sym
->section
->flags
& SEC_CODE
)
410 if (sym
->flags
& BSF_GLOBAL
)
414 else if ((sym
->name
[0] == '.' && sym
->name
[1] == 'L')
415 || ((sym
->flags
& BSF_LOCAL
)
416 && sym
->name
[0] == '$'
417 && sym
->name
[1] == 'L'))
418 /* Looks like a compiler-generated label. Skip it.
419 The assembler should be skipping these (to keep
420 executables small), but apparently with gcc on the
421 delta m88k SVR4, it loses. So to have us check too
422 should be harmless (but I encourage people to fix this
423 in the assembler instead of adding checks here). */
426 else if (sym
->name
[0] == '.' && sym
->name
[1] == '.')
428 /* Looks like a Harris compiler generated label for the
429 purpose of marking instructions that are relevant to
430 DWARF dies. The assembler can't get rid of these
431 because they are relocatable addresses that the
432 linker needs to resolve. */
438 ms_type
= mst_file_text
;
441 else if (sym
->section
->flags
& SEC_ALLOC
)
443 if (sym
->flags
& BSF_GLOBAL
)
445 if (sym
->section
->flags
& SEC_LOAD
)
454 else if (sym
->flags
& BSF_LOCAL
)
456 /* Named Local variable in a Data section. Check its
457 name for stabs-in-elf. The STREQ macro checks the
458 first character inline, so we only actually do a
459 strcmp function call on names that start with 'B'
461 index
= SECT_OFF_MAX
;
462 if (STREQ ("Bbss.bss", sym
->name
))
464 index
= SECT_OFF_BSS
;
466 else if (STREQ ("Ddata.data", sym
->name
))
468 index
= SECT_OFF_DATA
;
470 else if (STREQ ("Drodata.rodata", sym
->name
))
472 index
= SECT_OFF_RODATA
;
474 if (index
!= SECT_OFF_MAX
)
476 /* Found a special local symbol. Allocate a
477 sectinfo, if needed, and fill it in. */
478 if (sectinfo
== NULL
)
480 sectinfo
= (struct stab_section_info
*)
481 xmmalloc (objfile
->md
, sizeof (*sectinfo
));
482 memset ((PTR
) sectinfo
, 0, sizeof (*sectinfo
));
485 complain (§ion_info_complaint
,
491 (char *) filesym
->name
;
494 if (sectinfo
->sections
[index
] != 0)
496 complain (§ion_info_dup_complaint
,
499 /* Bfd symbols are section relative. */
500 symaddr
= sym
->value
+ sym
->section
->vma
;
501 /* Relocate non-absolute symbols by base address. */
502 if (sym
->section
!= &bfd_abs_section
)
506 sectinfo
->sections
[index
] = symaddr
;
507 /* The special local symbols don't go in the
508 minimal symbol table, so ignore this one. */
511 /* Not a special stabs-in-elf symbol, do regular
512 symbol processing. */
513 if (sym
->section
->flags
& SEC_LOAD
)
515 ms_type
= mst_file_data
;
519 ms_type
= mst_file_bss
;
524 ms_type
= mst_unknown
;
529 /* FIXME: Solaris2 shared libraries include lots of
530 odd "absolute" and "undefined" symbols, that play
531 hob with actions like finding what function the PC
532 is in. Ignore them if they aren't text, data, or bss. */
533 /* ms_type = mst_unknown; */
534 continue; /* Skip this symbol. */
536 /* Pass symbol size field in via BFD. FIXME!!! */
537 size
= ((elf_symbol_type
*) sym
)->internal_elf_sym
.st_size
;
538 msym
= record_minimal_symbol_and_info
539 ((char *) sym
->name
, symaddr
,
540 ms_type
, (PTR
) size
, sym
->section
, objfile
);
541 #ifdef SOFUN_ADDRESS_MAYBE_MISSING
543 msym
->filename
= filesymname
;
545 #ifdef ELF_MAKE_MSYMBOL_SPECIAL
546 ELF_MAKE_MSYMBOL_SPECIAL (sym
, msym
);
550 do_cleanups (back_to
);
554 /* Scan and build partial symbols for a symbol file.
555 We have been initialized by a call to elf_symfile_init, which
556 currently does nothing.
558 SECTION_OFFSETS is a set of offsets to apply to relocate the symbols
559 in each section. We simplify it down to a single offset for all
562 MAINLINE is true if we are reading the main symbol
563 table (as opposed to a shared lib or dynamically loaded file).
565 This function only does the minimum work necessary for letting the
566 user "name" things symbolically; it does not read the entire symtab.
567 Instead, it reads the external and static symbols and puts them in partial
568 symbol tables. When more extensive information is requested of a
569 file, the corresponding partial symbol table is mutated into a full
570 fledged symbol table by going back and reading the symbols
573 We look for sections with specific names, to tell us what debug
574 format to look for: FIXME!!!
576 dwarf_build_psymtabs() builds psymtabs for DWARF symbols;
577 elfstab_build_psymtabs() handles STABS symbols;
578 mdebug_build_psymtabs() handles ECOFF debugging information.
580 Note that ELF files have a "minimal" symbol table, which looks a lot
581 like a COFF symbol table, but has only the minimal information necessary
582 for linking. We process this also, and use the information to
583 build gdb's minimal symbol table. This gives us some minimal debugging
584 capability even for files compiled without -g. */
587 elf_symfile_read (objfile
, mainline
)
588 struct objfile
*objfile
;
591 bfd
*abfd
= objfile
->obfd
;
593 struct cleanup
*back_to
;
596 init_minimal_symbol_collection ();
597 back_to
= make_cleanup ((make_cleanup_func
) discard_minimal_symbols
, 0);
599 memset ((char *) &ei
, 0, sizeof (ei
));
601 /* Allocate struct to keep track of the symfile */
602 objfile
->sym_stab_info
= (struct dbx_symfile_info
*)
603 xmmalloc (objfile
->md
, sizeof (struct dbx_symfile_info
));
604 memset ((char *) objfile
->sym_stab_info
, 0, sizeof (struct dbx_symfile_info
));
605 make_cleanup (free_elfinfo
, (PTR
) objfile
);
607 /* Process the normal ELF symbol table first. This may write some
608 chain of info into the dbx_symfile_info in objfile->sym_stab_info,
609 which can later be used by elfstab_offset_sections. */
611 /* FIXME, should take a section_offsets param, not just an offset. */
612 offset
= ANOFFSET (objfile
->section_offsets
, 0);
613 elf_symtab_read (abfd
, offset
, objfile
, 0);
615 /* Add the dynamic symbols. */
617 elf_symtab_read (abfd
, offset
, objfile
, 1);
619 /* Now process debugging information, which is contained in
620 special ELF sections. */
622 /* If we are reinitializing, or if we have never loaded syms yet,
623 set table to empty. MAINLINE is cleared so that *_read_psymtab
624 functions do not all also re-initialize the psymbol table. */
627 init_psymbol_list (objfile
, 0);
631 /* We first have to find them... */
632 bfd_map_over_sections (abfd
, elf_locate_sections
, (PTR
) & ei
);
634 /* ELF debugging information is inserted into the psymtab in the
635 order of least informative first - most informative last. Since
636 the psymtab table is searched `most recent insertion first' this
637 increases the probability that more detailed debug information
638 for a section is found.
640 For instance, an object file might contain both .mdebug (XCOFF)
641 and .debug_info (DWARF2) sections then .mdebug is inserted first
642 (searched last) and DWARF2 is inserted last (searched first). If
643 we don't do this then the XCOFF info is found first - for code in
644 an included file XCOFF info is useless. */
648 const struct ecoff_debug_swap
*swap
;
650 /* .mdebug section, presumably holding ECOFF debugging
652 swap
= get_elf_backend_data (abfd
)->elf_backend_ecoff_debug_swap
;
654 elfmdebug_build_psymtabs (objfile
, swap
, ei
.mdebugsect
,
655 objfile
->section_offsets
);
661 /* Stab sections have an associated string table that looks like
662 a separate section. */
663 str_sect
= bfd_get_section_by_name (abfd
, ".stabstr");
665 /* FIXME should probably warn about a stab section without a stabstr. */
667 elfstab_build_psymtabs (objfile
,
669 ei
.stabsect
->filepos
,
670 bfd_section_size (abfd
, ei
.stabsect
),
672 bfd_section_size (abfd
, str_sect
));
674 if (dwarf2_has_info (abfd
))
676 /* DWARF 2 sections */
677 dwarf2_build_psymtabs (objfile
, objfile
->section_offsets
, mainline
);
679 else if (ei
.dboffset
&& ei
.lnoffset
)
682 dwarf_build_psymtabs (objfile
,
683 objfile
->section_offsets
, mainline
,
684 ei
.dboffset
, ei
.dbsize
,
685 ei
.lnoffset
, ei
.lnsize
);
688 /* Install any minimal symbols that have been collected as the current
689 minimal symbols for this objfile. */
691 install_minimal_symbols (objfile
);
693 do_cleanups (back_to
);
696 /* This cleans up the objfile's sym_stab_info pointer, and the chain of
697 stab_section_info's, that might be dangling from it. */
703 struct objfile
*objfile
= (struct objfile
*) objp
;
704 struct dbx_symfile_info
*dbxinfo
= objfile
->sym_stab_info
;
705 struct stab_section_info
*ssi
, *nssi
;
707 ssi
= dbxinfo
->stab_section_info
;
711 mfree (objfile
->md
, ssi
);
715 dbxinfo
->stab_section_info
= 0; /* Just say No mo info about this. */
719 /* Initialize anything that needs initializing when a completely new symbol
720 file is specified (not just adding some symbols from another file, e.g. a
723 We reinitialize buildsym, since we may be reading stabs from an ELF file. */
726 elf_new_init (ignore
)
727 struct objfile
*ignore
;
729 stabsread_new_init ();
730 buildsym_new_init ();
733 /* Perform any local cleanups required when we are done with a particular
734 objfile. I.E, we are in the process of discarding all symbol information
735 for an objfile, freeing up all memory held for it, and unlinking the
736 objfile struct from the global list of known objfiles. */
739 elf_symfile_finish (objfile
)
740 struct objfile
*objfile
;
742 if (objfile
->sym_stab_info
!= NULL
)
744 mfree (objfile
->md
, objfile
->sym_stab_info
);
748 /* ELF specific initialization routine for reading symbols.
750 It is passed a pointer to a struct sym_fns which contains, among other
751 things, the BFD for the file whose symbols are being read, and a slot for
752 a pointer to "private data" which we can fill with goodies.
754 For now at least, we have nothing in particular to do, so this function is
758 elf_symfile_init (objfile
)
759 struct objfile
*objfile
;
761 /* ELF objects may be reordered, so set OBJF_REORDERED. If we
762 find this causes a significant slowdown in gdb then we could
763 set it in the debug symbol readers only when necessary. */
764 objfile
->flags
|= OBJF_REORDERED
;
767 /* When handling an ELF file that contains Sun STABS debug info,
768 some of the debug info is relative to the particular chunk of the
769 section that was generated in its individual .o file. E.g.
770 offsets to static variables are relative to the start of the data
771 segment *for that module before linking*. This information is
772 painfully squirreled away in the ELF symbol table as local symbols
773 with wierd names. Go get 'em when needed. */
776 elfstab_offset_sections (objfile
, pst
)
777 struct objfile
*objfile
;
778 struct partial_symtab
*pst
;
780 char *filename
= pst
->filename
;
781 struct dbx_symfile_info
*dbx
= objfile
->sym_stab_info
;
782 struct stab_section_info
*maybe
= dbx
->stab_section_info
;
783 struct stab_section_info
*questionable
= 0;
787 /* The ELF symbol info doesn't include path names, so strip the path
788 (if any) from the psymtab filename. */
789 while (0 != (p
= strchr (filename
, '/')))
792 /* FIXME: This linear search could speed up significantly
793 if it was chained in the right order to match how we search it,
794 and if we unchained when we found a match. */
795 for (; maybe
; maybe
= maybe
->next
)
797 if (filename
[0] == maybe
->filename
[0]
798 && STREQ (filename
, maybe
->filename
))
800 /* We found a match. But there might be several source files
801 (from different directories) with the same name. */
802 if (0 == maybe
->found
)
804 questionable
= maybe
; /* Might use it later. */
808 if (maybe
== 0 && questionable
!= 0)
810 complain (&stab_info_questionable_complaint
, filename
);
811 maybe
= questionable
;
816 /* Found it! Allocate a new psymtab struct, and fill it in. */
818 pst
->section_offsets
= (struct section_offsets
*)
819 obstack_alloc (&objfile
->psymbol_obstack
, SIZEOF_SECTION_OFFSETS
);
820 for (i
= 0; i
< SECT_OFF_MAX
; i
++)
821 ANOFFSET (pst
->section_offsets
, i
) = maybe
->sections
[i
];
825 /* We were unable to find any offsets for this file. Complain. */
826 if (dbx
->stab_section_info
) /* If there *is* any info, */
827 complain (&stab_info_mismatch_complaint
, filename
);
830 /* Register that we are able to handle ELF object file formats. */
832 static struct sym_fns elf_sym_fns
=
834 bfd_target_elf_flavour
,
835 elf_new_init
, /* sym_new_init: init anything gbl to entire symtab */
836 elf_symfile_init
, /* sym_init: read initial info, setup for sym_read() */
837 elf_symfile_read
, /* sym_read: read a symbol file into symtab */
838 elf_symfile_finish
, /* sym_finish: finished with file, cleanup */
839 default_symfile_offsets
, /* sym_offsets: Translate ext. to int. relocation */
840 NULL
/* next: pointer to next struct sym_fns */
844 _initialize_elfread ()
846 add_symtab_fns (&elf_sym_fns
);