1 /* Read ELF (Executable and Linking Format) object files for GDB.
2 Copyright 1991, 1992, 1993, 1994, 1995, 1996 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, Boston, MA 02111-1307, USA. */
23 #include "gdb_string.h"
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 minimal_symbol
*
82 record_minimal_symbol_and_info
PARAMS ((char *, CORE_ADDR
,
83 enum minimal_symbol_type
, char *,
87 elf_locate_sections
PARAMS ((bfd
*, asection
*, void *));
89 /* We are called once per section from elf_symfile_read. We
90 need to examine each section we are passed, check to see
91 if it is something we are interested in processing, and
92 if so, stash away some access information for the section.
94 For now we recognize the dwarf debug information sections and
95 line number sections from matching their section names. The
96 ELF definition is no real help here since it has no direct
97 knowledge of DWARF (by design, so any debugging format can be
100 We also recognize the ".stab" sections used by the Sun compilers
101 released with Solaris 2.
103 FIXME: The section names should not be hardwired strings (what
104 should they be? I don't think most object file formats have enough
105 section flags to specify what kind of debug section it is
109 elf_locate_sections (ignore_abfd
, sectp
, eip
)
114 register struct elfinfo
*ei
;
116 ei
= (struct elfinfo
*) eip
;
117 if (STREQ (sectp
-> name
, ".debug"))
119 ei
-> dboffset
= sectp
-> filepos
;
120 ei
-> dbsize
= bfd_get_section_size_before_reloc (sectp
);
122 else if (STREQ (sectp
-> name
, ".line"))
124 ei
-> lnoffset
= sectp
-> filepos
;
125 ei
-> lnsize
= bfd_get_section_size_before_reloc (sectp
);
127 else if (STREQ (sectp
-> name
, ".stab"))
129 ei
-> stabsect
= sectp
;
131 else if (STREQ (sectp
-> name
, ".stab.index"))
133 ei
-> stabindexsect
= sectp
;
135 else if (STREQ (sectp
-> name
, ".mdebug"))
137 ei
-> mdebugsect
= sectp
;
141 #if 0 /* Currently unused */
144 elf_interpreter (abfd
)
151 interp_sec
= bfd_get_section_by_name (abfd
, ".interp");
154 size
= bfd_section_size (abfd
, interp_sec
);
155 interp
= alloca (size
);
156 if (bfd_get_section_contents (abfd
, interp_sec
, interp
, (file_ptr
)0,
159 interp
= savestring (interp
, size
- 1);
171 static struct minimal_symbol
*
172 record_minimal_symbol_and_info (name
, address
, ms_type
, info
, objfile
)
175 enum minimal_symbol_type ms_type
;
176 char *info
; /* FIXME, is this really char *? */
177 struct objfile
*objfile
;
181 /* Guess the section from the type. This is likely to be wrong in
187 section
= SECT_OFF_TEXT
;
188 #ifdef SMASH_TEXT_ADDRESS
189 SMASH_TEXT_ADDRESS (address
);
194 section
= SECT_OFF_DATA
;
198 section
= SECT_OFF_BSS
;
205 name
= obsavestring (name
, strlen (name
), &objfile
-> symbol_obstack
);
206 return prim_record_minimal_symbol_and_info
207 (name
, address
, ms_type
, info
, section
, objfile
);
214 elf_symtab_read -- read the symbol table of an ELF file
218 void elf_symtab_read (bfd *abfd, CORE_ADDR addr,
219 struct objfile *objfile, int dynamic)
223 Given an open bfd, a base address to relocate symbols to, and a
224 flag that specifies whether or not this bfd is for an executable
225 or not (may be shared library for example), add all the global
226 function and data symbols to the minimal symbol table.
228 In stabs-in-ELF, as implemented by Sun, there are some local symbols
229 defined in the ELF symbol table, which can be used to locate
230 the beginnings of sections from each ".o" file that was linked to
231 form the executable objfile. We gather any such info and record it
232 in data structures hung off the objfile's private data.
237 elf_symtab_read (abfd
, addr
, objfile
, dynamic
)
240 struct objfile
*objfile
;
245 asymbol
**symbol_table
;
246 long number_of_symbols
;
249 struct cleanup
*back_to
;
251 enum minimal_symbol_type ms_type
;
252 /* If sectinfo is nonNULL, it contains section info that should end up
253 filed in the objfile. */
254 struct stab_section_info
*sectinfo
= NULL
;
255 /* If filesym is nonzero, it points to a file symbol, but we haven't
256 seen any section info for it yet. */
257 asymbol
*filesym
= 0;
258 #ifdef SOFUN_ADDRESS_MAYBE_MISSING
259 /* Name of filesym, as saved on the symbol_obstack. */
260 char *filesymname
= obsavestring ("", 0, &objfile
->symbol_obstack
);
262 struct dbx_symfile_info
*dbx
= (struct dbx_symfile_info
*)
263 objfile
->sym_stab_info
;
265 int stripped
= (bfd_get_symcount (abfd
) == 0);
269 storage_needed
= bfd_get_dynamic_symtab_upper_bound (abfd
);
271 /* Nothing to be done if there is no dynamic symtab. */
272 if (storage_needed
< 0)
277 storage_needed
= bfd_get_symtab_upper_bound (abfd
);
278 if (storage_needed
< 0)
279 error ("Can't read symbols from %s: %s", bfd_get_filename (abfd
),
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 (abfd
,
290 number_of_symbols
= bfd_canonicalize_symtab (abfd
, symbol_table
);
291 if (number_of_symbols
< 0)
292 error ("Can't read symbols from %s: %s", bfd_get_filename (abfd
),
293 bfd_errmsg (bfd_get_error ()));
294 for (i
= 0; i
< number_of_symbols
; i
++)
296 sym
= symbol_table
[i
];
297 if (sym
-> name
== NULL
|| *sym
-> name
== '\0')
299 /* Skip names that don't exist (shouldn't happen), or names
300 that are null strings (may happen). */
305 && sym
-> section
== &bfd_und_section
306 && (sym
-> flags
& BSF_FUNCTION
))
308 struct minimal_symbol
*msym
;
310 /* Symbol is a reference to a function defined in
312 If its value is non zero then it is usually the address
313 of the corresponding entry in the procedure linkage table,
314 relative to the base address.
315 If its value is zero then the dynamic linker has to resolve
316 the symbol. We are unable to find any meaningful address
317 for this symbol in the executable file, so we skip it. */
318 symaddr
= sym
-> value
;
322 msym
= record_minimal_symbol_and_info
323 ((char *) sym
-> name
, symaddr
,
324 mst_solib_trampoline
, NULL
, objfile
);
325 #ifdef SOFUN_ADDRESS_MAYBE_MISSING
327 msym
->filename
= filesymname
;
332 /* If it is a nonstripped executable, do not enter dynamic
333 symbols, as the dynamic symbol table is usually a subset
334 of the main symbol table. */
335 if (dynamic
&& !stripped
)
337 if (sym
-> flags
& BSF_FILE
)
339 /* STT_FILE debugging symbol that helps stabs-in-elf debugging.
340 Chain any old one onto the objfile; remember new sym. */
341 if (sectinfo
!= NULL
)
343 sectinfo
-> next
= dbx
-> stab_section_info
;
344 dbx
-> stab_section_info
= sectinfo
;
348 #ifdef SOFUN_ADDRESS_MAYBE_MISSING
350 obsavestring ((char *)filesym
->name
, strlen (filesym
->name
),
351 &objfile
->symbol_obstack
);
354 else if (sym
-> flags
& (BSF_GLOBAL
| BSF_LOCAL
| BSF_WEAK
))
356 struct minimal_symbol
*msym
;
358 /* Select global/local/weak symbols. Note that bfd puts abs
359 symbols in their own section, so all symbols we are
360 interested in will have a section. */
361 /* Bfd symbols are section relative. */
362 symaddr
= sym
-> value
+ sym
-> section
-> vma
;
363 /* Relocate all non-absolute symbols by base address. */
364 if (sym
-> section
!= &bfd_abs_section
)
368 /* For non-absolute symbols, use the type of the section
369 they are relative to, to intuit text/data. Bfd provides
370 no way of figuring this out for absolute symbols. */
371 if (sym
-> section
== &bfd_abs_section
)
373 /* This is a hack to get the minimal symbol type
374 right for Irix 5, which has absolute adresses
375 with special section indices for dynamic symbols. */
376 unsigned short shndx
=
377 ((elf_symbol_type
*) sym
)->internal_elf_sym
.st_shndx
;
387 case SHN_MIPS_ACOMMON
:
394 else if (sym
-> section
-> flags
& SEC_CODE
)
396 if (sym
-> flags
& BSF_GLOBAL
)
400 else if ((sym
->name
[0] == '.' && sym
->name
[1] == 'L')
401 || ((sym
-> flags
& BSF_LOCAL
)
402 && sym
->name
[0] == '$'
403 && sym
->name
[1] == 'L'))
404 /* Looks like a compiler-generated label. Skip it.
405 The assembler should be skipping these (to keep
406 executables small), but apparently with gcc on the
407 delta m88k SVR4, it loses. So to have us check too
408 should be harmless (but I encourage people to fix this
409 in the assembler instead of adding checks here). */
413 ms_type
= mst_file_text
;
416 else if (sym
-> section
-> flags
& SEC_ALLOC
)
418 if (sym
-> flags
& BSF_GLOBAL
)
420 if (sym
-> section
-> flags
& SEC_LOAD
)
429 else if (sym
-> flags
& BSF_LOCAL
)
431 /* Named Local variable in a Data section. Check its
432 name for stabs-in-elf. The STREQ macro checks the
433 first character inline, so we only actually do a
434 strcmp function call on names that start with 'B'
436 index
= SECT_OFF_MAX
;
437 if (STREQ ("Bbss.bss", sym
-> name
))
439 index
= SECT_OFF_BSS
;
441 else if (STREQ ("Ddata.data", sym
-> name
))
443 index
= SECT_OFF_DATA
;
445 else if (STREQ ("Drodata.rodata", sym
-> name
))
447 index
= SECT_OFF_RODATA
;
449 if (index
!= SECT_OFF_MAX
)
451 /* Found a special local symbol. Allocate a
452 sectinfo, if needed, and fill it in. */
453 if (sectinfo
== NULL
)
455 sectinfo
= (struct stab_section_info
*)
456 xmmalloc (objfile
-> md
, sizeof (*sectinfo
));
457 memset ((PTR
) sectinfo
, 0, sizeof (*sectinfo
));
460 complain (§ion_info_complaint
,
465 sectinfo
-> filename
=
466 (char *) filesym
-> name
;
469 if (sectinfo
-> sections
[index
] != 0)
471 complain (§ion_info_dup_complaint
,
472 sectinfo
-> filename
);
474 /* Bfd symbols are section relative. */
475 symaddr
= sym
-> value
+ sym
-> section
-> vma
;
476 /* Relocate non-absolute symbols by base address. */
477 if (sym
-> section
!= &bfd_abs_section
)
481 sectinfo
-> sections
[index
] = symaddr
;
482 /* The special local symbols don't go in the
483 minimal symbol table, so ignore this one. */
486 /* Not a special stabs-in-elf symbol, do regular
487 symbol processing. */
488 if (sym
-> section
-> flags
& SEC_LOAD
)
490 ms_type
= mst_file_data
;
494 ms_type
= mst_file_bss
;
499 ms_type
= mst_unknown
;
504 /* FIXME: Solaris2 shared libraries include lots of
505 odd "absolute" and "undefined" symbols, that play
506 hob with actions like finding what function the PC
507 is in. Ignore them if they aren't text, data, or bss. */
508 /* ms_type = mst_unknown; */
509 continue; /* Skip this symbol. */
511 /* Pass symbol size field in via BFD. FIXME!!! */
512 size
= ((elf_symbol_type
*) sym
) -> internal_elf_sym
.st_size
;
513 msym
= record_minimal_symbol_and_info
514 ((char *) sym
-> name
, symaddr
,
515 ms_type
, (PTR
) size
, objfile
);
516 #ifdef SOFUN_ADDRESS_MAYBE_MISSING
518 msym
->filename
= filesymname
;
522 do_cleanups (back_to
);
526 /* Scan and build partial symbols for a symbol file.
527 We have been initialized by a call to elf_symfile_init, which
528 currently does nothing.
530 SECTION_OFFSETS is a set of offsets to apply to relocate the symbols
531 in each section. We simplify it down to a single offset for all
534 MAINLINE is true if we are reading the main symbol
535 table (as opposed to a shared lib or dynamically loaded file).
537 This function only does the minimum work necessary for letting the
538 user "name" things symbolically; it does not read the entire symtab.
539 Instead, it reads the external and static symbols and puts them in partial
540 symbol tables. When more extensive information is requested of a
541 file, the corresponding partial symbol table is mutated into a full
542 fledged symbol table by going back and reading the symbols
545 We look for sections with specific names, to tell us what debug
546 format to look for: FIXME!!!
548 dwarf_build_psymtabs() builds psymtabs for DWARF symbols;
549 elfstab_build_psymtabs() handles STABS symbols;
550 mdebug_build_psymtabs() handles ECOFF debugging information.
552 Note that ELF files have a "minimal" symbol table, which looks a lot
553 like a COFF symbol table, but has only the minimal information necessary
554 for linking. We process this also, and use the information to
555 build gdb's minimal symbol table. This gives us some minimal debugging
556 capability even for files compiled without -g. */
559 elf_symfile_read (objfile
, section_offsets
, mainline
)
560 struct objfile
*objfile
;
561 struct section_offsets
*section_offsets
;
564 bfd
*abfd
= objfile
->obfd
;
566 struct cleanup
*back_to
;
569 init_minimal_symbol_collection ();
570 back_to
= make_cleanup (discard_minimal_symbols
, 0);
572 memset ((char *) &ei
, 0, sizeof (ei
));
574 /* Allocate struct to keep track of the symfile */
575 objfile
->sym_stab_info
= (PTR
)
576 xmmalloc (objfile
-> md
, sizeof (struct dbx_symfile_info
));
577 memset ((char *) objfile
->sym_stab_info
, 0, sizeof (struct dbx_symfile_info
));
578 make_cleanup (free_elfinfo
, (PTR
) objfile
);
580 /* Process the normal ELF symbol table first. This may write some
581 chain of info into the dbx_symfile_info in objfile->sym_stab_info,
582 which can later be used by elfstab_offset_sections. */
584 /* FIXME, should take a section_offsets param, not just an offset. */
585 offset
= ANOFFSET (section_offsets
, 0);
586 elf_symtab_read (abfd
, offset
, objfile
, 0);
588 /* Add the dynamic symbols. */
590 elf_symtab_read (abfd
, offset
, objfile
, 1);
592 /* Now process debugging information, which is contained in
593 special ELF sections. We first have to find them... */
595 bfd_map_over_sections (abfd
, elf_locate_sections
, (PTR
) &ei
);
596 if (ei
.dboffset
&& ei
.lnoffset
)
599 dwarf_build_psymtabs (objfile
,
600 section_offsets
, mainline
,
601 ei
.dboffset
, ei
.dbsize
,
602 ei
.lnoffset
, ei
.lnsize
);
608 /* Stab sections have an associated string table that looks like
609 a separate section. */
610 str_sect
= bfd_get_section_by_name (abfd
, ".stabstr");
612 /* FIXME should probably warn about a stab section without a stabstr. */
614 elfstab_build_psymtabs (objfile
,
617 ei
.stabsect
->filepos
,
618 bfd_section_size (abfd
, ei
.stabsect
),
620 bfd_section_size (abfd
, str_sect
));
624 const struct ecoff_debug_swap
*swap
;
626 /* .mdebug section, presumably holding ECOFF debugging
628 swap
= get_elf_backend_data (abfd
)->elf_backend_ecoff_debug_swap
;
630 elfmdebug_build_psymtabs (objfile
, swap
, ei
.mdebugsect
,
634 /* Install any minimal symbols that have been collected as the current
635 minimal symbols for this objfile. */
637 install_minimal_symbols (objfile
);
639 do_cleanups (back_to
);
642 /* This cleans up the objfile's sym_stab_info pointer, and the chain of
643 stab_section_info's, that might be dangling from it. */
649 struct objfile
*objfile
= (struct objfile
*)objp
;
650 struct dbx_symfile_info
*dbxinfo
= (struct dbx_symfile_info
*)
651 objfile
->sym_stab_info
;
652 struct stab_section_info
*ssi
, *nssi
;
654 ssi
= dbxinfo
->stab_section_info
;
658 mfree (objfile
->md
, ssi
);
662 dbxinfo
->stab_section_info
= 0; /* Just say No mo info about this. */
666 /* Initialize anything that needs initializing when a completely new symbol
667 file is specified (not just adding some symbols from another file, e.g. a
670 We reinitialize buildsym, since we may be reading stabs from an ELF file. */
673 elf_new_init (ignore
)
674 struct objfile
*ignore
;
676 stabsread_new_init ();
677 buildsym_new_init ();
680 /* Perform any local cleanups required when we are done with a particular
681 objfile. I.E, we are in the process of discarding all symbol information
682 for an objfile, freeing up all memory held for it, and unlinking the
683 objfile struct from the global list of known objfiles. */
686 elf_symfile_finish (objfile
)
687 struct objfile
*objfile
;
689 if (objfile
-> sym_stab_info
!= NULL
)
691 mfree (objfile
-> md
, objfile
-> sym_stab_info
);
695 /* ELF specific initialization routine for reading symbols.
697 It is passed a pointer to a struct sym_fns which contains, among other
698 things, the BFD for the file whose symbols are being read, and a slot for
699 a pointer to "private data" which we can fill with goodies.
701 For now at least, we have nothing in particular to do, so this function is
705 elf_symfile_init (objfile
)
706 struct objfile
*objfile
;
708 /* ELF objects may be reordered, so set OBJF_REORDERED. If we
709 find this causes a significant slowdown in gdb then we could
710 set it in the debug symbol readers only when necessary. */
711 objfile
->flags
|= OBJF_REORDERED
;
714 /* When handling an ELF file that contains Sun STABS debug info,
715 some of the debug info is relative to the particular chunk of the
716 section that was generated in its individual .o file. E.g.
717 offsets to static variables are relative to the start of the data
718 segment *for that module before linking*. This information is
719 painfully squirreled away in the ELF symbol table as local symbols
720 with wierd names. Go get 'em when needed. */
723 elfstab_offset_sections (objfile
, pst
)
724 struct objfile
*objfile
;
725 struct partial_symtab
*pst
;
727 char *filename
= pst
->filename
;
728 struct dbx_symfile_info
*dbx
= (struct dbx_symfile_info
*)
729 objfile
->sym_stab_info
;
730 struct stab_section_info
*maybe
= dbx
->stab_section_info
;
731 struct stab_section_info
*questionable
= 0;
735 /* The ELF symbol info doesn't include path names, so strip the path
736 (if any) from the psymtab filename. */
737 while (0 != (p
= strchr (filename
, '/')))
740 /* FIXME: This linear search could speed up significantly
741 if it was chained in the right order to match how we search it,
742 and if we unchained when we found a match. */
743 for (; maybe
; maybe
= maybe
->next
)
745 if (filename
[0] == maybe
->filename
[0]
746 && STREQ (filename
, maybe
->filename
))
748 /* We found a match. But there might be several source files
749 (from different directories) with the same name. */
750 if (0 == maybe
->found
)
752 questionable
= maybe
; /* Might use it later. */
756 if (maybe
== 0 && questionable
!= 0)
758 complain (&stab_info_questionable_complaint
, filename
);
759 maybe
= questionable
;
764 /* Found it! Allocate a new psymtab struct, and fill it in. */
766 pst
->section_offsets
= (struct section_offsets
*)
767 obstack_alloc (&objfile
-> psymbol_obstack
,
768 sizeof (struct section_offsets
) +
769 sizeof (pst
->section_offsets
->offsets
) * (SECT_OFF_MAX
-1));
771 for (i
= 0; i
< SECT_OFF_MAX
; i
++)
772 ANOFFSET (pst
->section_offsets
, i
) = maybe
->sections
[i
];
776 /* We were unable to find any offsets for this file. Complain. */
777 if (dbx
->stab_section_info
) /* If there *is* any info, */
778 complain (&stab_info_mismatch_complaint
, filename
);
781 /* Register that we are able to handle ELF object file formats. */
783 static struct sym_fns elf_sym_fns
=
785 bfd_target_elf_flavour
,
786 elf_new_init
, /* sym_new_init: init anything gbl to entire symtab */
787 elf_symfile_init
, /* sym_init: read initial info, setup for sym_read() */
788 elf_symfile_read
, /* sym_read: read a symbol file into symtab */
789 elf_symfile_finish
, /* sym_finish: finished with file, cleanup */
790 default_symfile_offsets
,
791 /* sym_offsets: Translate ext. to int. relocation */
792 NULL
/* next: pointer to next struct sym_fns */
796 _initialize_elfread ()
798 add_symtab_fns (&elf_sym_fns
);