1 /* Read ELF (Executable and Linking Format) object files for GDB.
2 Copyright 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000,
4 Free Software Foundation, Inc.
5 Written by Fred Fish at Cygnus Support.
7 This file is part of GDB.
9 This program is free software; you can redistribute it and/or modify
10 it under the terms of the GNU General Public License as published by
11 the Free Software Foundation; either version 2 of the License, or
12 (at your option) any later version.
14 This program is distributed in the hope that it will be useful,
15 but WITHOUT ANY WARRANTY; without even the implied warranty of
16 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 GNU General Public License for more details.
19 You should have received a copy of the GNU General Public License
20 along with this program; if not, write to the Free Software
21 Foundation, Inc., 59 Temple Place - Suite 330,
22 Boston, MA 02111-1307, USA. */
26 #include "gdb_string.h"
33 #include "stabsread.h"
34 #include "gdb-stabs.h"
35 #include "complaints.h"
38 extern void _initialize_elfread (void);
40 /* The struct elfinfo is available only during ELF symbol table and
41 psymtab reading. It is destroyed at the completion of psymtab-reading.
42 It's local to elf_symfile_read. */
46 file_ptr dboffset
; /* Offset to dwarf debug section */
47 unsigned int dbsize
; /* Size of dwarf debug section */
48 file_ptr lnoffset
; /* Offset to dwarf line number section */
49 unsigned int lnsize
; /* Size of dwarf line number section */
50 asection
*stabsect
; /* Section pointer for .stab section */
51 asection
*stabindexsect
; /* Section pointer for .stab.index section */
52 asection
*mdebugsect
; /* Section pointer for .mdebug section */
55 /* Various things we might complain about... */
57 struct complaint section_info_complaint
=
58 {"elf/stab section information %s without a preceding file symbol", 0, 0};
60 struct complaint section_info_dup_complaint
=
61 {"duplicated elf/stab section information for %s", 0, 0};
63 struct complaint stab_info_mismatch_complaint
=
64 {"elf/stab section information missing for %s", 0, 0};
66 struct complaint stab_info_questionable_complaint
=
67 {"elf/stab section information questionable for %s", 0, 0};
69 static void free_elfinfo (void *);
71 /* We are called once per section from elf_symfile_read. We
72 need to examine each section we are passed, check to see
73 if it is something we are interested in processing, and
74 if so, stash away some access information for the section.
76 For now we recognize the dwarf debug information sections and
77 line number sections from matching their section names. The
78 ELF definition is no real help here since it has no direct
79 knowledge of DWARF (by design, so any debugging format can be
82 We also recognize the ".stab" sections used by the Sun compilers
83 released with Solaris 2.
85 FIXME: The section names should not be hardwired strings (what
86 should they be? I don't think most object file formats have enough
87 section flags to specify what kind of debug section it is
91 elf_locate_sections (bfd
*ignore_abfd
, asection
*sectp
, void *eip
)
93 register struct elfinfo
*ei
;
95 ei
= (struct elfinfo
*) eip
;
96 if (STREQ (sectp
->name
, ".debug"))
98 ei
->dboffset
= sectp
->filepos
;
99 ei
->dbsize
= bfd_get_section_size_before_reloc (sectp
);
101 else if (STREQ (sectp
->name
, ".line"))
103 ei
->lnoffset
= sectp
->filepos
;
104 ei
->lnsize
= bfd_get_section_size_before_reloc (sectp
);
106 else if (STREQ (sectp
->name
, ".stab"))
108 ei
->stabsect
= sectp
;
110 else if (STREQ (sectp
->name
, ".stab.index"))
112 ei
->stabindexsect
= sectp
;
114 else if (STREQ (sectp
->name
, ".mdebug"))
116 ei
->mdebugsect
= sectp
;
120 #if 0 /* Currently unused */
123 elf_interpreter (bfd
*abfd
)
129 interp_sec
= bfd_get_section_by_name (abfd
, ".interp");
132 size
= bfd_section_size (abfd
, interp_sec
);
133 interp
= alloca (size
);
134 if (bfd_get_section_contents (abfd
, interp_sec
, interp
, (file_ptr
) 0,
137 interp
= savestring (interp
, size
- 1);
149 static struct minimal_symbol
*
150 record_minimal_symbol_and_info (char *name
, CORE_ADDR address
,
151 enum minimal_symbol_type ms_type
, char *info
, /* FIXME, is this really char *? */
152 asection
*bfd_section
, struct objfile
*objfile
)
154 if (ms_type
== mst_text
|| ms_type
== mst_file_text
)
155 address
= SMASH_TEXT_ADDRESS (address
);
157 return prim_record_minimal_symbol_and_info
158 (name
, address
, ms_type
, info
, bfd_section
->index
, bfd_section
, objfile
);
165 elf_symtab_read -- read the symbol table of an ELF file
169 void elf_symtab_read (struct objfile *objfile, int dynamic)
173 Given an objfile and a flag that specifies whether or not the objfile
174 is for an executable or not (may be shared library for example), add
175 all the global function and data symbols to the minimal symbol table.
177 In stabs-in-ELF, as implemented by Sun, there are some local symbols
178 defined in the ELF symbol table, which can be used to locate
179 the beginnings of sections from each ".o" file that was linked to
180 form the executable objfile. We gather any such info and record it
181 in data structures hung off the objfile's private data.
186 elf_symtab_read (struct objfile
*objfile
, int dynamic
)
190 asymbol
**symbol_table
;
191 long number_of_symbols
;
194 struct cleanup
*back_to
;
197 enum minimal_symbol_type ms_type
;
198 /* If sectinfo is nonNULL, it contains section info that should end up
199 filed in the objfile. */
200 struct stab_section_info
*sectinfo
= NULL
;
201 /* If filesym is nonzero, it points to a file symbol, but we haven't
202 seen any section info for it yet. */
203 asymbol
*filesym
= 0;
204 #ifdef SOFUN_ADDRESS_MAYBE_MISSING
205 /* Name of filesym, as saved on the symbol_obstack. */
206 char *filesymname
= obsavestring ("", 0, &objfile
->symbol_obstack
);
208 struct dbx_symfile_info
*dbx
= objfile
->sym_stab_info
;
210 int stripped
= (bfd_get_symcount (objfile
->obfd
) == 0);
214 storage_needed
= bfd_get_dynamic_symtab_upper_bound (objfile
->obfd
);
216 /* Nothing to be done if there is no dynamic symtab. */
217 if (storage_needed
< 0)
222 storage_needed
= bfd_get_symtab_upper_bound (objfile
->obfd
);
223 if (storage_needed
< 0)
224 error ("Can't read symbols from %s: %s", bfd_get_filename (objfile
->obfd
),
225 bfd_errmsg (bfd_get_error ()));
227 if (storage_needed
> 0)
229 symbol_table
= (asymbol
**) xmalloc (storage_needed
);
230 back_to
= make_cleanup (xfree
, symbol_table
);
232 number_of_symbols
= bfd_canonicalize_dynamic_symtab (objfile
->obfd
,
235 number_of_symbols
= bfd_canonicalize_symtab (objfile
->obfd
, symbol_table
);
236 if (number_of_symbols
< 0)
237 error ("Can't read symbols from %s: %s", bfd_get_filename (objfile
->obfd
),
238 bfd_errmsg (bfd_get_error ()));
240 for (i
= 0; i
< number_of_symbols
; i
++)
242 sym
= symbol_table
[i
];
243 if (sym
->name
== NULL
|| *sym
->name
== '\0')
245 /* Skip names that don't exist (shouldn't happen), or names
246 that are null strings (may happen). */
250 offset
= ANOFFSET (objfile
->section_offsets
, sym
->section
->index
);
252 && sym
->section
== &bfd_und_section
253 && (sym
->flags
& BSF_FUNCTION
))
255 struct minimal_symbol
*msym
;
257 /* Symbol is a reference to a function defined in
259 If its value is non zero then it is usually the address
260 of the corresponding entry in the procedure linkage table,
261 plus the desired section offset.
262 If its value is zero then the dynamic linker has to resolve
263 the symbol. We are unable to find any meaningful address
264 for this symbol in the executable file, so we skip it. */
265 symaddr
= sym
->value
;
269 msym
= record_minimal_symbol_and_info
270 ((char *) sym
->name
, symaddr
,
271 mst_solib_trampoline
, NULL
, sym
->section
, objfile
);
272 #ifdef SOFUN_ADDRESS_MAYBE_MISSING
274 msym
->filename
= filesymname
;
279 /* If it is a nonstripped executable, do not enter dynamic
280 symbols, as the dynamic symbol table is usually a subset
281 of the main symbol table. */
282 if (dynamic
&& !stripped
)
284 if (sym
->flags
& BSF_FILE
)
286 /* STT_FILE debugging symbol that helps stabs-in-elf debugging.
287 Chain any old one onto the objfile; remember new sym. */
288 if (sectinfo
!= NULL
)
290 sectinfo
->next
= dbx
->stab_section_info
;
291 dbx
->stab_section_info
= sectinfo
;
295 #ifdef SOFUN_ADDRESS_MAYBE_MISSING
297 obsavestring ((char *) filesym
->name
, strlen (filesym
->name
),
298 &objfile
->symbol_obstack
);
301 else if (sym
->flags
& (BSF_GLOBAL
| BSF_LOCAL
| BSF_WEAK
))
303 struct minimal_symbol
*msym
;
305 /* Select global/local/weak symbols. Note that bfd puts abs
306 symbols in their own section, so all symbols we are
307 interested in will have a section. */
308 /* Bfd symbols are section relative. */
309 symaddr
= sym
->value
+ sym
->section
->vma
;
310 /* Relocate all non-absolute symbols by the section offset. */
311 if (sym
->section
!= &bfd_abs_section
)
315 /* For non-absolute symbols, use the type of the section
316 they are relative to, to intuit text/data. Bfd provides
317 no way of figuring this out for absolute symbols. */
318 if (sym
->section
== &bfd_abs_section
)
320 /* This is a hack to get the minimal symbol type
321 right for Irix 5, which has absolute addresses
322 with special section indices for dynamic symbols. */
323 unsigned short shndx
=
324 ((elf_symbol_type
*) sym
)->internal_elf_sym
.st_shndx
;
334 case SHN_MIPS_ACOMMON
:
341 /* If it is an Irix dynamic symbol, skip section name
342 symbols, relocate all others by section offset. */
343 if (ms_type
!= mst_abs
)
345 if (sym
->name
[0] == '.')
350 else if (sym
->section
->flags
& SEC_CODE
)
352 if (sym
->flags
& BSF_GLOBAL
)
356 else if ((sym
->name
[0] == '.' && sym
->name
[1] == 'L')
357 || ((sym
->flags
& BSF_LOCAL
)
358 && sym
->name
[0] == '$'
359 && sym
->name
[1] == 'L'))
360 /* Looks like a compiler-generated label. Skip
361 it. The assembler should be skipping these (to
362 keep executables small), but apparently with
363 gcc on the (OBSOLETE) delta m88k SVR4, it
364 loses. So to have us check too should be
365 harmless (but I encourage people to fix this in
366 the assembler instead of adding checks here). */
370 ms_type
= mst_file_text
;
373 else if (sym
->section
->flags
& SEC_ALLOC
)
375 if (sym
->flags
& (BSF_GLOBAL
| BSF_WEAK
))
377 if (sym
->section
->flags
& SEC_LOAD
)
386 else if (sym
->flags
& BSF_LOCAL
)
388 /* Named Local variable in a Data section. Check its
389 name for stabs-in-elf. The STREQ macro checks the
390 first character inline, so we only actually do a
391 strcmp function call on names that start with 'B'
393 index
= SECT_OFF_MAX
;
394 if (STREQ ("Bbss.bss", sym
->name
))
396 index
= SECT_OFF_BSS (objfile
);
398 else if (STREQ ("Ddata.data", sym
->name
))
400 index
= SECT_OFF_DATA (objfile
);
402 else if (STREQ ("Drodata.rodata", sym
->name
))
404 index
= SECT_OFF_RODATA (objfile
);
406 if (index
!= SECT_OFF_MAX
)
408 /* Found a special local symbol. Allocate a
409 sectinfo, if needed, and fill it in. */
410 if (sectinfo
== NULL
)
412 sectinfo
= (struct stab_section_info
*)
413 xmmalloc (objfile
->md
, sizeof (*sectinfo
));
418 complain (§ion_info_complaint
,
424 (char *) filesym
->name
;
429 if (sectinfo
->sections
[index
] != 0)
431 complain (§ion_info_dup_complaint
,
436 internal_error (__FILE__
, __LINE__
,
437 "Section index uninitialized.");
438 /* Bfd symbols are section relative. */
439 symaddr
= sym
->value
+ sym
->section
->vma
;
440 /* Relocate non-absolute symbols by the section offset. */
441 if (sym
->section
!= &bfd_abs_section
)
446 sectinfo
->sections
[index
] = symaddr
;
448 internal_error (__FILE__
, __LINE__
,
449 "Section index uninitialized.");
450 /* The special local symbols don't go in the
451 minimal symbol table, so ignore this one. */
454 /* Not a special stabs-in-elf symbol, do regular
455 symbol processing. */
456 if (sym
->section
->flags
& SEC_LOAD
)
458 ms_type
= mst_file_data
;
462 ms_type
= mst_file_bss
;
467 ms_type
= mst_unknown
;
472 /* FIXME: Solaris2 shared libraries include lots of
473 odd "absolute" and "undefined" symbols, that play
474 hob with actions like finding what function the PC
475 is in. Ignore them if they aren't text, data, or bss. */
476 /* ms_type = mst_unknown; */
477 continue; /* Skip this symbol. */
479 /* Pass symbol size field in via BFD. FIXME!!! */
480 size
= ((elf_symbol_type
*) sym
)->internal_elf_sym
.st_size
;
481 msym
= record_minimal_symbol_and_info
482 ((char *) sym
->name
, symaddr
,
483 ms_type
, (void *) size
, sym
->section
, objfile
);
484 #ifdef SOFUN_ADDRESS_MAYBE_MISSING
486 msym
->filename
= filesymname
;
488 ELF_MAKE_MSYMBOL_SPECIAL (sym
, msym
);
491 do_cleanups (back_to
);
495 /* Scan and build partial symbols for a symbol file.
496 We have been initialized by a call to elf_symfile_init, which
497 currently does nothing.
499 SECTION_OFFSETS is a set of offsets to apply to relocate the symbols
500 in each section. We simplify it down to a single offset for all
503 MAINLINE is true if we are reading the main symbol
504 table (as opposed to a shared lib or dynamically loaded file).
506 This function only does the minimum work necessary for letting the
507 user "name" things symbolically; it does not read the entire symtab.
508 Instead, it reads the external and static symbols and puts them in partial
509 symbol tables. When more extensive information is requested of a
510 file, the corresponding partial symbol table is mutated into a full
511 fledged symbol table by going back and reading the symbols
514 We look for sections with specific names, to tell us what debug
515 format to look for: FIXME!!!
517 dwarf_build_psymtabs() builds psymtabs for DWARF symbols;
518 elfstab_build_psymtabs() handles STABS symbols;
519 mdebug_build_psymtabs() handles ECOFF debugging information.
521 Note that ELF files have a "minimal" symbol table, which looks a lot
522 like a COFF symbol table, but has only the minimal information necessary
523 for linking. We process this also, and use the information to
524 build gdb's minimal symbol table. This gives us some minimal debugging
525 capability even for files compiled without -g. */
528 elf_symfile_read (struct objfile
*objfile
, int mainline
)
530 bfd
*abfd
= objfile
->obfd
;
532 struct cleanup
*back_to
;
535 init_minimal_symbol_collection ();
536 back_to
= make_cleanup_discard_minimal_symbols ();
538 memset ((char *) &ei
, 0, sizeof (ei
));
540 /* Allocate struct to keep track of the symfile */
541 objfile
->sym_stab_info
= (struct dbx_symfile_info
*)
542 xmmalloc (objfile
->md
, sizeof (struct dbx_symfile_info
));
543 memset ((char *) objfile
->sym_stab_info
, 0, sizeof (struct dbx_symfile_info
));
544 make_cleanup (free_elfinfo
, (void *) objfile
);
546 /* Process the normal ELF symbol table first. This may write some
547 chain of info into the dbx_symfile_info in objfile->sym_stab_info,
548 which can later be used by elfstab_offset_sections. */
550 elf_symtab_read (objfile
, 0);
552 /* Add the dynamic symbols. */
554 elf_symtab_read (objfile
, 1);
556 /* Now process debugging information, which is contained in
557 special ELF sections. */
559 /* If we are reinitializing, or if we have never loaded syms yet,
560 set table to empty. MAINLINE is cleared so that *_read_psymtab
561 functions do not all also re-initialize the psymbol table. */
564 init_psymbol_list (objfile
, 0);
568 /* We first have to find them... */
569 bfd_map_over_sections (abfd
, elf_locate_sections
, (void *) & ei
);
571 /* ELF debugging information is inserted into the psymtab in the
572 order of least informative first - most informative last. Since
573 the psymtab table is searched `most recent insertion first' this
574 increases the probability that more detailed debug information
575 for a section is found.
577 For instance, an object file might contain both .mdebug (XCOFF)
578 and .debug_info (DWARF2) sections then .mdebug is inserted first
579 (searched last) and DWARF2 is inserted last (searched first). If
580 we don't do this then the XCOFF info is found first - for code in
581 an included file XCOFF info is useless. */
585 const struct ecoff_debug_swap
*swap
;
587 /* .mdebug section, presumably holding ECOFF debugging
589 swap
= get_elf_backend_data (abfd
)->elf_backend_ecoff_debug_swap
;
591 elfmdebug_build_psymtabs (objfile
, swap
, ei
.mdebugsect
);
597 /* Stab sections have an associated string table that looks like
598 a separate section. */
599 str_sect
= bfd_get_section_by_name (abfd
, ".stabstr");
601 /* FIXME should probably warn about a stab section without a stabstr. */
603 elfstab_build_psymtabs (objfile
,
605 ei
.stabsect
->filepos
,
606 bfd_section_size (abfd
, ei
.stabsect
),
608 bfd_section_size (abfd
, str_sect
));
610 if (dwarf2_has_info (abfd
))
612 /* DWARF 2 sections */
613 dwarf2_build_psymtabs (objfile
, mainline
);
615 else if (ei
.dboffset
&& ei
.lnoffset
)
618 dwarf_build_psymtabs (objfile
,
620 ei
.dboffset
, ei
.dbsize
,
621 ei
.lnoffset
, ei
.lnsize
);
624 if (DWARF2_BUILD_FRAME_INFO_P ())
625 DWARF2_BUILD_FRAME_INFO(objfile
);
627 /* Install any minimal symbols that have been collected as the current
628 minimal symbols for this objfile. */
630 install_minimal_symbols (objfile
);
632 do_cleanups (back_to
);
635 /* This cleans up the objfile's sym_stab_info pointer, and the chain of
636 stab_section_info's, that might be dangling from it. */
639 free_elfinfo (void *objp
)
641 struct objfile
*objfile
= (struct objfile
*) objp
;
642 struct dbx_symfile_info
*dbxinfo
= objfile
->sym_stab_info
;
643 struct stab_section_info
*ssi
, *nssi
;
645 ssi
= dbxinfo
->stab_section_info
;
649 xmfree (objfile
->md
, ssi
);
653 dbxinfo
->stab_section_info
= 0; /* Just say No mo info about this. */
657 /* Initialize anything that needs initializing when a completely new symbol
658 file is specified (not just adding some symbols from another file, e.g. a
661 We reinitialize buildsym, since we may be reading stabs from an ELF file. */
664 elf_new_init (struct objfile
*ignore
)
666 stabsread_new_init ();
667 buildsym_new_init ();
670 /* Perform any local cleanups required when we are done with a particular
671 objfile. I.E, we are in the process of discarding all symbol information
672 for an objfile, freeing up all memory held for it, and unlinking the
673 objfile struct from the global list of known objfiles. */
676 elf_symfile_finish (struct objfile
*objfile
)
678 if (objfile
->sym_stab_info
!= NULL
)
680 xmfree (objfile
->md
, objfile
->sym_stab_info
);
684 /* ELF specific initialization routine for reading symbols.
686 It is passed a pointer to a struct sym_fns which contains, among other
687 things, the BFD for the file whose symbols are being read, and a slot for
688 a pointer to "private data" which we can fill with goodies.
690 For now at least, we have nothing in particular to do, so this function is
694 elf_symfile_init (struct objfile
*objfile
)
696 /* ELF objects may be reordered, so set OBJF_REORDERED. If we
697 find this causes a significant slowdown in gdb then we could
698 set it in the debug symbol readers only when necessary. */
699 objfile
->flags
|= OBJF_REORDERED
;
702 /* When handling an ELF file that contains Sun STABS debug info,
703 some of the debug info is relative to the particular chunk of the
704 section that was generated in its individual .o file. E.g.
705 offsets to static variables are relative to the start of the data
706 segment *for that module before linking*. This information is
707 painfully squirreled away in the ELF symbol table as local symbols
708 with wierd names. Go get 'em when needed. */
711 elfstab_offset_sections (struct objfile
*objfile
, struct partial_symtab
*pst
)
713 char *filename
= pst
->filename
;
714 struct dbx_symfile_info
*dbx
= objfile
->sym_stab_info
;
715 struct stab_section_info
*maybe
= dbx
->stab_section_info
;
716 struct stab_section_info
*questionable
= 0;
720 /* The ELF symbol info doesn't include path names, so strip the path
721 (if any) from the psymtab filename. */
722 while (0 != (p
= strchr (filename
, '/')))
725 /* FIXME: This linear search could speed up significantly
726 if it was chained in the right order to match how we search it,
727 and if we unchained when we found a match. */
728 for (; maybe
; maybe
= maybe
->next
)
730 if (filename
[0] == maybe
->filename
[0]
731 && STREQ (filename
, maybe
->filename
))
733 /* We found a match. But there might be several source files
734 (from different directories) with the same name. */
735 if (0 == maybe
->found
)
737 questionable
= maybe
; /* Might use it later. */
741 if (maybe
== 0 && questionable
!= 0)
743 complain (&stab_info_questionable_complaint
, filename
);
744 maybe
= questionable
;
749 /* Found it! Allocate a new psymtab struct, and fill it in. */
751 pst
->section_offsets
= (struct section_offsets
*)
752 obstack_alloc (&objfile
->psymbol_obstack
, SIZEOF_SECTION_OFFSETS
);
753 for (i
= 0; i
< SECT_OFF_MAX
; i
++)
754 (pst
->section_offsets
)->offsets
[i
] = maybe
->sections
[i
];
758 /* We were unable to find any offsets for this file. Complain. */
759 if (dbx
->stab_section_info
) /* If there *is* any info, */
760 complain (&stab_info_mismatch_complaint
, filename
);
763 /* Register that we are able to handle ELF object file formats. */
765 static struct sym_fns elf_sym_fns
=
767 bfd_target_elf_flavour
,
768 elf_new_init
, /* sym_new_init: init anything gbl to entire symtab */
769 elf_symfile_init
, /* sym_init: read initial info, setup for sym_read() */
770 elf_symfile_read
, /* sym_read: read a symbol file into symtab */
771 elf_symfile_finish
, /* sym_finish: finished with file, cleanup */
772 default_symfile_offsets
, /* sym_offsets: Translate ext. to int. relocation */
773 NULL
/* next: pointer to next struct sym_fns */
777 _initialize_elfread (void)
779 add_symtab_fns (&elf_sym_fns
);