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
->name
[0] == '.'
353 && (strncmp (sym
->name
+ 1, "objc_", 4) == 0))
355 /* Looks like an Objective-C special symbol */
358 else if (sym
->flags
& BSF_GLOBAL
)
362 else if ((sym
->name
[0] == '.' && sym
->name
[1] == 'L')
363 || ((sym
->flags
& BSF_LOCAL
)
364 && sym
->name
[0] == '$'
365 && sym
->name
[1] == 'L'))
366 /* Looks like a compiler-generated label. Skip
367 it. The assembler should be skipping these (to
368 keep executables small), but apparently with
369 gcc on the (OBSOLETE) delta m88k SVR4, it
370 loses. So to have us check too should be
371 harmless (but I encourage people to fix this in
372 the assembler instead of adding checks here). */
376 ms_type
= mst_file_text
;
379 else if (sym
->section
->flags
& SEC_ALLOC
)
381 if (sym
->flags
& (BSF_GLOBAL
| BSF_WEAK
))
383 if (sym
->section
->flags
& SEC_LOAD
)
392 else if (sym
->flags
& BSF_LOCAL
)
394 /* Named Local variable in a Data section. Check its
395 name for stabs-in-elf. The STREQ macro checks the
396 first character inline, so we only actually do a
397 strcmp function call on names that start with 'B'
399 index
= SECT_OFF_MAX
;
400 if (STREQ ("Bbss.bss", sym
->name
))
402 index
= SECT_OFF_BSS (objfile
);
404 else if (STREQ ("Ddata.data", sym
->name
))
406 index
= SECT_OFF_DATA (objfile
);
408 else if (STREQ ("Drodata.rodata", sym
->name
))
410 index
= SECT_OFF_RODATA (objfile
);
412 if (index
!= SECT_OFF_MAX
)
414 /* Found a special local symbol. Allocate a
415 sectinfo, if needed, and fill it in. */
416 if (sectinfo
== NULL
)
418 sectinfo
= (struct stab_section_info
*)
419 xmmalloc (objfile
->md
, sizeof (*sectinfo
));
424 complain (§ion_info_complaint
,
430 (char *) filesym
->name
;
435 if (sectinfo
->sections
[index
] != 0)
437 complain (§ion_info_dup_complaint
,
442 internal_error (__FILE__
, __LINE__
,
443 "Section index uninitialized.");
444 /* Bfd symbols are section relative. */
445 symaddr
= sym
->value
+ sym
->section
->vma
;
446 /* Relocate non-absolute symbols by the section offset. */
447 if (sym
->section
!= &bfd_abs_section
)
452 sectinfo
->sections
[index
] = symaddr
;
454 internal_error (__FILE__
, __LINE__
,
455 "Section index uninitialized.");
456 /* The special local symbols don't go in the
457 minimal symbol table, so ignore this one. */
460 /* Not a special stabs-in-elf symbol, do regular
461 symbol processing. */
462 if (sym
->section
->flags
& SEC_LOAD
)
464 ms_type
= mst_file_data
;
468 ms_type
= mst_file_bss
;
473 ms_type
= mst_unknown
;
478 /* FIXME: Solaris2 shared libraries include lots of
479 odd "absolute" and "undefined" symbols, that play
480 hob with actions like finding what function the PC
481 is in. Ignore them if they aren't text, data, or bss. */
482 /* ms_type = mst_unknown; */
483 continue; /* Skip this symbol. */
485 /* Pass symbol size field in via BFD. FIXME!!! */
486 size
= ((elf_symbol_type
*) sym
)->internal_elf_sym
.st_size
;
487 msym
= record_minimal_symbol_and_info
488 ((char *) sym
->name
, symaddr
,
489 ms_type
, (void *) size
, sym
->section
, objfile
);
490 #ifdef SOFUN_ADDRESS_MAYBE_MISSING
492 msym
->filename
= filesymname
;
494 ELF_MAKE_MSYMBOL_SPECIAL (sym
, msym
);
497 do_cleanups (back_to
);
501 /* Scan and build partial symbols for a symbol file.
502 We have been initialized by a call to elf_symfile_init, which
503 currently does nothing.
505 SECTION_OFFSETS is a set of offsets to apply to relocate the symbols
506 in each section. We simplify it down to a single offset for all
509 MAINLINE is true if we are reading the main symbol
510 table (as opposed to a shared lib or dynamically loaded file).
512 This function only does the minimum work necessary for letting the
513 user "name" things symbolically; it does not read the entire symtab.
514 Instead, it reads the external and static symbols and puts them in partial
515 symbol tables. When more extensive information is requested of a
516 file, the corresponding partial symbol table is mutated into a full
517 fledged symbol table by going back and reading the symbols
520 We look for sections with specific names, to tell us what debug
521 format to look for: FIXME!!!
523 dwarf_build_psymtabs() builds psymtabs for DWARF symbols;
524 elfstab_build_psymtabs() handles STABS symbols;
525 mdebug_build_psymtabs() handles ECOFF debugging information.
527 Note that ELF files have a "minimal" symbol table, which looks a lot
528 like a COFF symbol table, but has only the minimal information necessary
529 for linking. We process this also, and use the information to
530 build gdb's minimal symbol table. This gives us some minimal debugging
531 capability even for files compiled without -g. */
534 elf_symfile_read (struct objfile
*objfile
, int mainline
)
536 bfd
*abfd
= objfile
->obfd
;
538 struct cleanup
*back_to
;
541 init_minimal_symbol_collection ();
542 back_to
= make_cleanup_discard_minimal_symbols ();
544 memset ((char *) &ei
, 0, sizeof (ei
));
546 /* Allocate struct to keep track of the symfile */
547 objfile
->sym_stab_info
= (struct dbx_symfile_info
*)
548 xmmalloc (objfile
->md
, sizeof (struct dbx_symfile_info
));
549 memset ((char *) objfile
->sym_stab_info
, 0, sizeof (struct dbx_symfile_info
));
550 make_cleanup (free_elfinfo
, (void *) objfile
);
552 /* Process the normal ELF symbol table first. This may write some
553 chain of info into the dbx_symfile_info in objfile->sym_stab_info,
554 which can later be used by elfstab_offset_sections. */
556 elf_symtab_read (objfile
, 0);
558 /* Add the dynamic symbols. */
560 elf_symtab_read (objfile
, 1);
562 /* Now process debugging information, which is contained in
563 special ELF sections. */
565 /* If we are reinitializing, or if we have never loaded syms yet,
566 set table to empty. MAINLINE is cleared so that *_read_psymtab
567 functions do not all also re-initialize the psymbol table. */
570 init_psymbol_list (objfile
, 0);
574 /* We first have to find them... */
575 bfd_map_over_sections (abfd
, elf_locate_sections
, (void *) & ei
);
577 /* ELF debugging information is inserted into the psymtab in the
578 order of least informative first - most informative last. Since
579 the psymtab table is searched `most recent insertion first' this
580 increases the probability that more detailed debug information
581 for a section is found.
583 For instance, an object file might contain both .mdebug (XCOFF)
584 and .debug_info (DWARF2) sections then .mdebug is inserted first
585 (searched last) and DWARF2 is inserted last (searched first). If
586 we don't do this then the XCOFF info is found first - for code in
587 an included file XCOFF info is useless. */
591 const struct ecoff_debug_swap
*swap
;
593 /* .mdebug section, presumably holding ECOFF debugging
595 swap
= get_elf_backend_data (abfd
)->elf_backend_ecoff_debug_swap
;
597 elfmdebug_build_psymtabs (objfile
, swap
, ei
.mdebugsect
);
603 /* Stab sections have an associated string table that looks like
604 a separate section. */
605 str_sect
= bfd_get_section_by_name (abfd
, ".stabstr");
607 /* FIXME should probably warn about a stab section without a stabstr. */
609 elfstab_build_psymtabs (objfile
,
611 ei
.stabsect
->filepos
,
612 bfd_section_size (abfd
, ei
.stabsect
),
614 bfd_section_size (abfd
, str_sect
));
616 if (dwarf2_has_info (abfd
))
618 /* DWARF 2 sections */
619 dwarf2_build_psymtabs (objfile
, mainline
);
621 else if (ei
.dboffset
&& ei
.lnoffset
)
624 dwarf_build_psymtabs (objfile
,
626 ei
.dboffset
, ei
.dbsize
,
627 ei
.lnoffset
, ei
.lnsize
);
630 if (DWARF2_BUILD_FRAME_INFO_P ())
631 DWARF2_BUILD_FRAME_INFO(objfile
);
633 /* Install any minimal symbols that have been collected as the current
634 minimal symbols for this objfile. */
636 install_minimal_symbols (objfile
);
638 do_cleanups (back_to
);
641 /* This cleans up the objfile's sym_stab_info pointer, and the chain of
642 stab_section_info's, that might be dangling from it. */
645 free_elfinfo (void *objp
)
647 struct objfile
*objfile
= (struct objfile
*) objp
;
648 struct dbx_symfile_info
*dbxinfo
= objfile
->sym_stab_info
;
649 struct stab_section_info
*ssi
, *nssi
;
651 ssi
= dbxinfo
->stab_section_info
;
655 xmfree (objfile
->md
, ssi
);
659 dbxinfo
->stab_section_info
= 0; /* Just say No mo info about this. */
663 /* Initialize anything that needs initializing when a completely new symbol
664 file is specified (not just adding some symbols from another file, e.g. a
667 We reinitialize buildsym, since we may be reading stabs from an ELF file. */
670 elf_new_init (struct objfile
*ignore
)
672 stabsread_new_init ();
673 buildsym_new_init ();
676 /* Perform any local cleanups required when we are done with a particular
677 objfile. I.E, we are in the process of discarding all symbol information
678 for an objfile, freeing up all memory held for it, and unlinking the
679 objfile struct from the global list of known objfiles. */
682 elf_symfile_finish (struct objfile
*objfile
)
684 if (objfile
->sym_stab_info
!= NULL
)
686 xmfree (objfile
->md
, objfile
->sym_stab_info
);
690 /* ELF specific initialization routine for reading symbols.
692 It is passed a pointer to a struct sym_fns which contains, among other
693 things, the BFD for the file whose symbols are being read, and a slot for
694 a pointer to "private data" which we can fill with goodies.
696 For now at least, we have nothing in particular to do, so this function is
700 elf_symfile_init (struct objfile
*objfile
)
702 /* ELF objects may be reordered, so set OBJF_REORDERED. If we
703 find this causes a significant slowdown in gdb then we could
704 set it in the debug symbol readers only when necessary. */
705 objfile
->flags
|= OBJF_REORDERED
;
708 /* When handling an ELF file that contains Sun STABS debug info,
709 some of the debug info is relative to the particular chunk of the
710 section that was generated in its individual .o file. E.g.
711 offsets to static variables are relative to the start of the data
712 segment *for that module before linking*. This information is
713 painfully squirreled away in the ELF symbol table as local symbols
714 with wierd names. Go get 'em when needed. */
717 elfstab_offset_sections (struct objfile
*objfile
, struct partial_symtab
*pst
)
719 char *filename
= pst
->filename
;
720 struct dbx_symfile_info
*dbx
= objfile
->sym_stab_info
;
721 struct stab_section_info
*maybe
= dbx
->stab_section_info
;
722 struct stab_section_info
*questionable
= 0;
726 /* The ELF symbol info doesn't include path names, so strip the path
727 (if any) from the psymtab filename. */
728 while (0 != (p
= strchr (filename
, '/')))
731 /* FIXME: This linear search could speed up significantly
732 if it was chained in the right order to match how we search it,
733 and if we unchained when we found a match. */
734 for (; maybe
; maybe
= maybe
->next
)
736 if (filename
[0] == maybe
->filename
[0]
737 && STREQ (filename
, maybe
->filename
))
739 /* We found a match. But there might be several source files
740 (from different directories) with the same name. */
741 if (0 == maybe
->found
)
743 questionable
= maybe
; /* Might use it later. */
747 if (maybe
== 0 && questionable
!= 0)
749 complain (&stab_info_questionable_complaint
, filename
);
750 maybe
= questionable
;
755 /* Found it! Allocate a new psymtab struct, and fill it in. */
757 pst
->section_offsets
= (struct section_offsets
*)
758 obstack_alloc (&objfile
->psymbol_obstack
, SIZEOF_SECTION_OFFSETS
);
759 for (i
= 0; i
< SECT_OFF_MAX
; i
++)
760 (pst
->section_offsets
)->offsets
[i
] = maybe
->sections
[i
];
764 /* We were unable to find any offsets for this file. Complain. */
765 if (dbx
->stab_section_info
) /* If there *is* any info, */
766 complain (&stab_info_mismatch_complaint
, filename
);
769 /* Register that we are able to handle ELF object file formats. */
771 static struct sym_fns elf_sym_fns
=
773 bfd_target_elf_flavour
,
774 elf_new_init
, /* sym_new_init: init anything gbl to entire symtab */
775 elf_symfile_init
, /* sym_init: read initial info, setup for sym_read() */
776 elf_symfile_read
, /* sym_read: read a symbol file into symtab */
777 elf_symfile_finish
, /* sym_finish: finished with file, cleanup */
778 default_symfile_offsets
, /* sym_offsets: Translate ext. to int. relocation */
779 NULL
/* next: pointer to next struct sym_fns */
783 _initialize_elfread (void)
785 add_symtab_fns (&elf_sym_fns
);