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35f5886e FF |
1 | /* Read ELF (Executable and Linking Format) object files for GDB. |
2 | Copyright (C) 1991 Free Software Foundation, Inc. | |
3 | Written by Fred Fish at Cygnus Support. | |
4 | ||
5 | This file is part of GDB. | |
6 | ||
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. | |
11 | ||
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. | |
16 | ||
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., 675 Mass Ave, Cambridge, MA 02139, USA. */ | |
20 | ||
21 | /************************************************************************ | |
22 | * * | |
23 | * NOTICE * | |
24 | * * | |
25 | * This file is still under construction. When it is complete, this * | |
26 | * notice will be removed. Until then, direct any questions or changes * | |
27 | * to Fred Fish at Cygnus Support (fnf@cygint) * | |
28 | * * | |
29 | * FIXME Still needs support for shared libraries. * | |
30 | * FIXME Still needs support for core files. * | |
31 | * FIXME The ".debug" and ".line" section names are hardwired. * | |
32 | * FIXME Still needs support ELF symbol tables (as distinct * | |
33 | * from DWARF support). Can use them to build the misc * | |
34 | * function vector at least. This is fairly trivial once * | |
35 | * bfd is extended to handle ELF symbol tables. * | |
36 | * * | |
37 | ************************************************************************/ | |
38 | ||
39 | #include <stdio.h> | |
40 | ||
41 | #include "defs.h" | |
f5f0679a SC |
42 | #include "elf/common.h" |
43 | #include "elf/external.h" | |
44 | #include "elf/internal.h" | |
35f5886e FF |
45 | #include "bfd.h" |
46 | #include "symfile.h" | |
47 | #include "symtab.h" | |
48 | #include "ansidecl.h" | |
49 | ||
a048c8f5 JG |
50 | extern int EXFUN (strcmp, (CONST char *a, CONST char *b)); |
51 | extern int EXFUN (dwarf_build_psymtabs, | |
52 | (int desc, char *filename, CORE_ADDR addr, int mainline, | |
53 | unsigned int dbfoff, unsigned int dbsize, unsigned int lnoffset, | |
54 | unsigned int lnsize, struct objfile *objfile)); | |
55 | ||
35f5886e FF |
56 | #define STREQ(a,b) (strcmp((a),(b))==0) |
57 | ||
58 | struct elfinfo { | |
59 | unsigned int dboffset; /* Offset to dwarf debug section */ | |
60 | unsigned int dbsize; /* Size of dwarf debug section */ | |
61 | unsigned int lnoffset; /* Offset to dwarf line number section */ | |
62 | unsigned int lnsize; /* Size of dwarf line number section */ | |
63 | }; | |
64 | ||
35f5886e FF |
65 | /* We are called once per section from elf_symfile_read. We |
66 | need to examine each section we are passed, check to see | |
67 | if it is something we are interested in processing, and | |
68 | if so, stash away some access information for the section. | |
69 | ||
70 | For now we recognize the dwarf debug information sections and | |
71 | line number sections from matching their section names. The | |
72 | ELF definition is no real help here since it has no direct | |
73 | knowledge of DWARF (by design, so any debugging format can be | |
74 | used). | |
75 | ||
76 | FIXME: The section names should not be hardwired strings. */ | |
77 | ||
78 | static void | |
79 | DEFUN(elf_locate_sections, (abfd, sectp, ei), | |
80 | bfd *abfd AND | |
81 | asection *sectp AND | |
82 | struct elfinfo *ei) | |
83 | { | |
84 | if (STREQ (sectp -> name, ".debug")) | |
85 | { | |
86 | ei -> dboffset = sectp -> filepos; | |
87 | ei -> dbsize = sectp -> size; | |
88 | } | |
89 | else if (STREQ (sectp -> name, ".line")) | |
90 | { | |
91 | ei -> lnoffset = sectp -> filepos; | |
92 | ei -> lnsize = sectp -> size; | |
93 | } | |
94 | } | |
95 | ||
a7446af6 FF |
96 | /* |
97 | ||
98 | LOCAL FUNCTION | |
99 | ||
100 | record_misc_function -- add entry to miscellaneous function vector | |
101 | ||
102 | SYNOPSIS | |
103 | ||
104 | static void record_misc_function (char *name, CORE_ADDR address) | |
105 | ||
106 | DESCRIPTION | |
107 | ||
108 | Given a pointer to the name of a symbol that should be added to the | |
109 | miscellaneous function vector, and the address associated with that | |
110 | symbol, records this information for later use in building the | |
111 | miscellaneous function vector. | |
112 | ||
113 | NOTES | |
114 | ||
115 | FIXME: For now we just use mf_unknown as the type. This should be | |
116 | fixed. | |
117 | */ | |
118 | ||
119 | static void | |
120 | DEFUN(record_misc_function, (name, address), char *name AND CORE_ADDR address) | |
121 | { | |
122 | prim_record_misc_function (obsavestring (name, strlen (name)), address, | |
123 | mf_unknown); | |
124 | } | |
125 | ||
126 | static void | |
127 | DEFUN (elf_symtab_read, (abfd, addr), | |
128 | bfd *abfd AND | |
129 | CORE_ADDR addr) | |
130 | { | |
131 | unsigned int storage_needed; | |
132 | asymbol *sym; | |
133 | asymbol **symbol_table; | |
134 | unsigned int number_of_symbols; | |
135 | unsigned int i; | |
136 | struct cleanup *back_to; | |
137 | ||
138 | storage_needed = get_symtab_upper_bound (abfd); | |
139 | ||
140 | if (storage_needed > 0) | |
141 | { | |
142 | symbol_table = (asymbol **) bfd_xmalloc (storage_needed); | |
143 | back_to = make_cleanup (free, symbol_table); | |
144 | number_of_symbols = bfd_canonicalize_symtab (abfd, symbol_table); | |
145 | ||
146 | for (i = 0; i < number_of_symbols; i++) | |
147 | { | |
148 | sym = *symbol_table++; | |
149 | /* Select global symbols that are defined in a specific section | |
150 | or are absolute. */ | |
151 | if (sym -> flags & BSF_GLOBAL | |
152 | && ((sym -> section != NULL) || (sym -> flags & BSF_ABSOLUTE))) | |
153 | { | |
154 | record_misc_function ((char *) sym -> name, sym -> value); | |
155 | } | |
156 | } | |
157 | do_cleanups (back_to); | |
158 | } | |
159 | } | |
160 | ||
35f5886e FF |
161 | /* Scan and build partial symbols for a symbol file. |
162 | We have been initialized by a call to elf_symfile_init, which | |
163 | currently does nothing. | |
164 | ||
165 | ADDR is the address relative to which the symbols in it are (e.g. | |
166 | the base address of the text segment). | |
167 | ||
168 | MAINLINE is true if we are reading the main symbol | |
169 | table (as opposed to a shared lib or dynamically loaded file). | |
170 | ||
171 | This function only does the minimum work necessary for letting the | |
172 | user "name" things symbolically; it does not read the entire symtab. | |
173 | Instead, it reads the external and static symbols and puts them in partial | |
174 | symbol tables. When more extensive information is requested of a | |
175 | file, the corresponding partial symbol table is mutated into a full | |
176 | fledged symbol table by going back and reading the symbols | |
177 | for real. The function dwarf_psymtab_to_symtab() is the function that | |
a7446af6 FF |
178 | does this for DWARF symbols. |
179 | ||
180 | Note that ELF files have a "minimal" symbol table, which looks a lot | |
181 | like a COFF symbol table, but has only the minimal information necessary | |
182 | for linking. We process this also, and just use the information to | |
183 | add to the misc function vector. This gives us some minimal debugging | |
184 | capability even for files compiled without -g. | |
185 | */ | |
35f5886e FF |
186 | |
187 | static void | |
188 | DEFUN(elf_symfile_read, (sf, addr, mainline), | |
189 | struct sym_fns *sf AND | |
190 | CORE_ADDR addr AND | |
191 | int mainline) | |
192 | { | |
a048c8f5 | 193 | bfd *abfd = sf->objfile->obfd; |
35f5886e | 194 | struct elfinfo ei; |
a7446af6 | 195 | struct cleanup *back_to; |
35f5886e | 196 | |
a7446af6 FF |
197 | init_misc_bunches (); |
198 | back_to = make_cleanup (discard_misc_bunches, 0); | |
199 | ||
200 | /* Process the normal ELF symbol table first. */ | |
201 | ||
202 | elf_symtab_read (abfd, addr); | |
203 | ||
204 | /* Now process the DWARF debugging information, which is contained in | |
205 | special ELF sections. We first have to find them... */ | |
206 | ||
207 | (void) memset ((char *) &ei, 0, sizeof (ei)); | |
35f5886e FF |
208 | bfd_map_over_sections (abfd, elf_locate_sections, &ei); |
209 | if (ei.dboffset && ei.lnoffset) | |
210 | { | |
211 | addr = 0; /* FIXME: force address base to zero for now */ | |
212 | dwarf_build_psymtabs (fileno ((FILE *)(abfd -> iostream)), | |
213 | bfd_get_filename (abfd), | |
214 | addr, mainline, | |
215 | ei.dboffset, ei.dbsize, | |
a048c8f5 | 216 | ei.lnoffset, ei.lnsize, sf->objfile); |
35f5886e | 217 | } |
a7446af6 | 218 | |
35f5886e FF |
219 | if (!partial_symtab_list) |
220 | { | |
221 | wrap_here (""); | |
222 | printf_filtered ("(no debugging symbols found)..."); | |
223 | wrap_here (""); | |
224 | } | |
a7446af6 FF |
225 | |
226 | /* Go over the miscellaneous functions and install them in the | |
227 | miscellaneous function vector. */ | |
228 | ||
229 | condense_misc_bunches (!mainline); | |
230 | do_cleanups (back_to); | |
35f5886e FF |
231 | } |
232 | ||
233 | /* Initialize anything that needs initializing when a completely new symbol | |
234 | file is specified (not just adding some symbols from another file, e.g. a | |
235 | shared library). | |
236 | ||
237 | For now at least, we have nothing in particular to do, so this function is | |
238 | just a stub. */ | |
239 | ||
240 | static void | |
241 | DEFUN_VOID (elf_new_init) | |
242 | { | |
243 | } | |
244 | ||
245 | /* ELF specific initialization routine for reading symbols. | |
246 | ||
247 | It is passed a pointer to a struct sym_fns which contains, among other | |
248 | things, the BFD for the file whose symbols are being read, and a slot for | |
249 | a pointer to "private data" which we can fill with goodies. | |
250 | ||
251 | For now at least, we have nothing in particular to do, so this function is | |
252 | just a stub. */ | |
253 | ||
254 | static void | |
255 | DEFUN(elf_symfile_init, (sf), | |
256 | struct sym_fns *sf) | |
257 | { | |
258 | } | |
259 | ||
260 | \f | |
261 | /* Register that we are able to handle ELF object file formats and DWARF | |
262 | debugging formats. | |
263 | ||
264 | Unlike other object file formats, where the debugging information format | |
265 | is implied by the object file format, the ELF object file format and the | |
266 | DWARF debugging information format are two distinct, and potentially | |
267 | separate entities. I.E. it is perfectly possible to have ELF objects | |
268 | with debugging formats other than DWARF. And it is conceivable that the | |
269 | DWARF debugging format might be used with another object file format, | |
270 | like COFF, by simply using COFF's custom section feature. | |
271 | ||
272 | GDB, and to a lesser extent BFD, should support the notion of separate | |
273 | object file formats and debugging information formats. For now, we just | |
274 | use "elf" in the same sense as "a.out" or "coff", to imply both the ELF | |
275 | object file format and the DWARF debugging format. */ | |
276 | ||
277 | static struct sym_fns elf_sym_fns = { | |
278 | "elf", /* sym_name: name or name prefix of BFD target type */ | |
279 | 3, /* sym_namelen: number of significant sym_name chars */ | |
280 | elf_new_init, /* sym_new_init: init anything gbl to entire symtab */ | |
281 | elf_symfile_init, /* sym_init: read initial info, setup for sym_read() */ | |
282 | elf_symfile_read, /* sym_read: read a symbol file into symtab */ | |
283 | NULL, /* sym_bfd: accessor for symbol file being read */ | |
284 | NULL, /* sym_private: sym_init & sym_read shared info */ | |
285 | NULL /* next: pointer to next struct sym_fns */ | |
286 | }; | |
287 | ||
288 | void | |
289 | DEFUN_VOID (_initialize_elfread) | |
290 | { | |
291 | add_symtab_fns (&elf_sym_fns); | |
292 | } |