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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 | ||
f8b76e70 FF |
96 | char * |
97 | DEFUN(elf_interpreter, (abfd), | |
98 | bfd *abfd) | |
99 | { | |
100 | sec_ptr interp_sec; | |
101 | unsigned size; | |
102 | char *interp = NULL; | |
103 | ||
104 | interp_sec = bfd_get_section_by_name (abfd, ".interp"); | |
105 | if (interp_sec) | |
106 | { | |
107 | size = bfd_section_size (abfd, interp_sec); | |
108 | interp = alloca (size); | |
109 | if (bfd_get_section_contents (abfd, interp_sec, interp, (file_ptr)0, | |
110 | size)) | |
111 | { | |
112 | interp = savestring (interp, size - 1); | |
113 | } | |
114 | else | |
115 | { | |
116 | interp = NULL; | |
117 | } | |
118 | } | |
119 | return (interp); | |
120 | } | |
121 | ||
a7446af6 FF |
122 | /* |
123 | ||
124 | LOCAL FUNCTION | |
125 | ||
126 | record_misc_function -- add entry to miscellaneous function vector | |
127 | ||
128 | SYNOPSIS | |
129 | ||
130 | static void record_misc_function (char *name, CORE_ADDR address) | |
131 | ||
132 | DESCRIPTION | |
133 | ||
134 | Given a pointer to the name of a symbol that should be added to the | |
135 | miscellaneous function vector, and the address associated with that | |
136 | symbol, records this information for later use in building the | |
137 | miscellaneous function vector. | |
138 | ||
139 | NOTES | |
140 | ||
141 | FIXME: For now we just use mf_unknown as the type. This should be | |
142 | fixed. | |
143 | */ | |
144 | ||
145 | static void | |
f8b76e70 FF |
146 | DEFUN(record_misc_function, (name, address, mf_type), |
147 | char *name AND CORE_ADDR address AND enum misc_function_type mf_type) | |
a7446af6 FF |
148 | { |
149 | prim_record_misc_function (obsavestring (name, strlen (name)), address, | |
f8b76e70 | 150 | mf_type); |
a7446af6 FF |
151 | } |
152 | ||
f8b76e70 FF |
153 | /* |
154 | ||
155 | LOCAL FUNCTION | |
156 | ||
157 | elf_symtab_read -- read the symbol table of an ELF file | |
158 | ||
159 | SYNOPSIS | |
160 | ||
161 | void elf_symtab_read (bfd *abfd, CORE_ADDR addr, int mainline) | |
162 | ||
163 | DESCRIPTION | |
164 | ||
165 | Given an open bfd, a base address to relocate symbols to, and a | |
166 | flag that specifies whether or not this bfd is for an executable | |
167 | or not (may be shared library for example), add all the global | |
168 | function and data symbols to the miscellaneous function vector. | |
169 | ||
170 | */ | |
171 | ||
a7446af6 | 172 | static void |
f8b76e70 | 173 | DEFUN (elf_symtab_read, (abfd, addr, mainline), |
a7446af6 | 174 | bfd *abfd AND |
f8b76e70 FF |
175 | CORE_ADDR addr AND |
176 | int mainline) | |
a7446af6 FF |
177 | { |
178 | unsigned int storage_needed; | |
179 | asymbol *sym; | |
180 | asymbol **symbol_table; | |
181 | unsigned int number_of_symbols; | |
182 | unsigned int i; | |
183 | struct cleanup *back_to; | |
f8b76e70 FF |
184 | CORE_ADDR symaddr; |
185 | enum misc_function_type mf_type; | |
a7446af6 FF |
186 | |
187 | storage_needed = get_symtab_upper_bound (abfd); | |
188 | ||
189 | if (storage_needed > 0) | |
190 | { | |
191 | symbol_table = (asymbol **) bfd_xmalloc (storage_needed); | |
192 | back_to = make_cleanup (free, symbol_table); | |
193 | number_of_symbols = bfd_canonicalize_symtab (abfd, symbol_table); | |
194 | ||
195 | for (i = 0; i < number_of_symbols; i++) | |
196 | { | |
197 | sym = *symbol_table++; | |
198 | /* Select global symbols that are defined in a specific section | |
199 | or are absolute. */ | |
200 | if (sym -> flags & BSF_GLOBAL | |
201 | && ((sym -> section != NULL) || (sym -> flags & BSF_ABSOLUTE))) | |
202 | { | |
f8b76e70 FF |
203 | symaddr = sym -> value; |
204 | if (!mainline) | |
205 | { | |
206 | /* Relocate all symbols by base address */ | |
207 | symaddr += addr; | |
208 | } | |
209 | /* For non-absolute symbols, use the type of the section | |
210 | they are relative to, to intuit text/data. Bfd provides | |
211 | no way of figuring this out for absolute symbols. */ | |
212 | if (sym -> section && (sym -> section -> flags & SEC_CODE)) | |
213 | { | |
214 | mf_type = mf_text; | |
215 | } | |
216 | else if (sym -> section && (sym -> section -> flags & SEC_DATA)) | |
217 | { | |
218 | mf_type = mf_data; | |
219 | } | |
220 | else | |
221 | { | |
222 | mf_type = mf_unknown; | |
223 | } | |
224 | record_misc_function ((char *) sym -> name, symaddr, mf_type); | |
a7446af6 FF |
225 | } |
226 | } | |
227 | do_cleanups (back_to); | |
228 | } | |
229 | } | |
230 | ||
35f5886e FF |
231 | /* Scan and build partial symbols for a symbol file. |
232 | We have been initialized by a call to elf_symfile_init, which | |
233 | currently does nothing. | |
234 | ||
235 | ADDR is the address relative to which the symbols in it are (e.g. | |
236 | the base address of the text segment). | |
237 | ||
238 | MAINLINE is true if we are reading the main symbol | |
239 | table (as opposed to a shared lib or dynamically loaded file). | |
240 | ||
241 | This function only does the minimum work necessary for letting the | |
242 | user "name" things symbolically; it does not read the entire symtab. | |
243 | Instead, it reads the external and static symbols and puts them in partial | |
244 | symbol tables. When more extensive information is requested of a | |
245 | file, the corresponding partial symbol table is mutated into a full | |
246 | fledged symbol table by going back and reading the symbols | |
247 | for real. The function dwarf_psymtab_to_symtab() is the function that | |
a7446af6 FF |
248 | does this for DWARF symbols. |
249 | ||
250 | Note that ELF files have a "minimal" symbol table, which looks a lot | |
251 | like a COFF symbol table, but has only the minimal information necessary | |
252 | for linking. We process this also, and just use the information to | |
253 | add to the misc function vector. This gives us some minimal debugging | |
254 | capability even for files compiled without -g. | |
255 | */ | |
35f5886e FF |
256 | |
257 | static void | |
258 | DEFUN(elf_symfile_read, (sf, addr, mainline), | |
259 | struct sym_fns *sf AND | |
260 | CORE_ADDR addr AND | |
261 | int mainline) | |
262 | { | |
a048c8f5 | 263 | bfd *abfd = sf->objfile->obfd; |
35f5886e | 264 | struct elfinfo ei; |
a7446af6 | 265 | struct cleanup *back_to; |
35f5886e | 266 | |
a7446af6 FF |
267 | init_misc_bunches (); |
268 | back_to = make_cleanup (discard_misc_bunches, 0); | |
269 | ||
270 | /* Process the normal ELF symbol table first. */ | |
271 | ||
f8b76e70 | 272 | elf_symtab_read (abfd, addr, mainline); |
a7446af6 FF |
273 | |
274 | /* Now process the DWARF debugging information, which is contained in | |
275 | special ELF sections. We first have to find them... */ | |
276 | ||
277 | (void) memset ((char *) &ei, 0, sizeof (ei)); | |
35f5886e FF |
278 | bfd_map_over_sections (abfd, elf_locate_sections, &ei); |
279 | if (ei.dboffset && ei.lnoffset) | |
280 | { | |
35f5886e FF |
281 | dwarf_build_psymtabs (fileno ((FILE *)(abfd -> iostream)), |
282 | bfd_get_filename (abfd), | |
283 | addr, mainline, | |
284 | ei.dboffset, ei.dbsize, | |
a048c8f5 | 285 | ei.lnoffset, ei.lnsize, sf->objfile); |
35f5886e | 286 | } |
a7446af6 | 287 | |
35f5886e FF |
288 | if (!partial_symtab_list) |
289 | { | |
290 | wrap_here (""); | |
291 | printf_filtered ("(no debugging symbols found)..."); | |
292 | wrap_here (""); | |
293 | } | |
a7446af6 FF |
294 | |
295 | /* Go over the miscellaneous functions and install them in the | |
296 | miscellaneous function vector. */ | |
297 | ||
298 | condense_misc_bunches (!mainline); | |
299 | do_cleanups (back_to); | |
35f5886e FF |
300 | } |
301 | ||
302 | /* Initialize anything that needs initializing when a completely new symbol | |
303 | file is specified (not just adding some symbols from another file, e.g. a | |
304 | shared library). | |
305 | ||
306 | For now at least, we have nothing in particular to do, so this function is | |
307 | just a stub. */ | |
308 | ||
309 | static void | |
310 | DEFUN_VOID (elf_new_init) | |
311 | { | |
312 | } | |
313 | ||
314 | /* ELF specific initialization routine for reading symbols. | |
315 | ||
316 | It is passed a pointer to a struct sym_fns which contains, among other | |
317 | things, the BFD for the file whose symbols are being read, and a slot for | |
318 | a pointer to "private data" which we can fill with goodies. | |
319 | ||
320 | For now at least, we have nothing in particular to do, so this function is | |
321 | just a stub. */ | |
322 | ||
323 | static void | |
324 | DEFUN(elf_symfile_init, (sf), | |
325 | struct sym_fns *sf) | |
326 | { | |
327 | } | |
328 | ||
329 | \f | |
330 | /* Register that we are able to handle ELF object file formats and DWARF | |
331 | debugging formats. | |
332 | ||
333 | Unlike other object file formats, where the debugging information format | |
334 | is implied by the object file format, the ELF object file format and the | |
335 | DWARF debugging information format are two distinct, and potentially | |
336 | separate entities. I.E. it is perfectly possible to have ELF objects | |
337 | with debugging formats other than DWARF. And it is conceivable that the | |
338 | DWARF debugging format might be used with another object file format, | |
339 | like COFF, by simply using COFF's custom section feature. | |
340 | ||
341 | GDB, and to a lesser extent BFD, should support the notion of separate | |
342 | object file formats and debugging information formats. For now, we just | |
343 | use "elf" in the same sense as "a.out" or "coff", to imply both the ELF | |
344 | object file format and the DWARF debugging format. */ | |
345 | ||
346 | static struct sym_fns elf_sym_fns = { | |
347 | "elf", /* sym_name: name or name prefix of BFD target type */ | |
348 | 3, /* sym_namelen: number of significant sym_name chars */ | |
349 | elf_new_init, /* sym_new_init: init anything gbl to entire symtab */ | |
350 | elf_symfile_init, /* sym_init: read initial info, setup for sym_read() */ | |
351 | elf_symfile_read, /* sym_read: read a symbol file into symtab */ | |
352 | NULL, /* sym_bfd: accessor for symbol file being read */ | |
353 | NULL, /* sym_private: sym_init & sym_read shared info */ | |
354 | NULL /* next: pointer to next struct sym_fns */ | |
355 | }; | |
356 | ||
357 | void | |
358 | DEFUN_VOID (_initialize_elfread) | |
359 | { | |
360 | add_symtab_fns (&elf_sym_fns); | |
361 | } |