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32090b8e KR |
1 | /* ELF executable support for BFD. |
2 | Copyright 1993 Free Software Foundation, Inc. | |
3 | ||
4 | This file is part of BFD, the Binary File Descriptor library. | |
5 | ||
6 | This program is free software; you can redistribute it and/or modify | |
7 | it under the terms of the GNU General Public License as published by | |
8 | the Free Software Foundation; either version 2 of the License, or | |
9 | (at your option) any later version. | |
10 | ||
11 | This program is distributed in the hope that it will be useful, | |
12 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
14 | GNU General Public License for more details. | |
15 | ||
16 | You should have received a copy of the GNU General Public License | |
17 | along with this program; if not, write to the Free Software | |
18 | Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */ | |
19 | ||
d1b44e83 ILT |
20 | /* |
21 | ||
22 | SECTION | |
23 | ELF backends | |
24 | ||
25 | BFD support for ELF formats is being worked on. | |
26 | Currently, the best supported back ends are for sparc and i386 | |
27 | (running svr4 or Solaris 2). | |
28 | ||
29 | Documentation of the internals of the support code still needs | |
30 | to be written. The code is changing quickly enough that we | |
31 | haven't bothered yet. | |
32 | */ | |
33 | ||
32090b8e KR |
34 | #include "bfd.h" |
35 | #include "sysdep.h" | |
013dec1a | 36 | #include "bfdlink.h" |
32090b8e KR |
37 | #include "libbfd.h" |
38 | #define ARCH_SIZE 0 | |
39 | #include "libelf.h" | |
40 | ||
32090b8e KR |
41 | /* Standard ELF hash function. Do not change this function; you will |
42 | cause invalid hash tables to be generated. (Well, you would if this | |
43 | were being used yet.) */ | |
44 | unsigned long | |
013dec1a ILT |
45 | bfd_elf_hash (name) |
46 | CONST unsigned char *name; | |
32090b8e KR |
47 | { |
48 | unsigned long h = 0; | |
49 | unsigned long g; | |
50 | int ch; | |
51 | ||
52 | while ((ch = *name++) != '\0') | |
53 | { | |
54 | h = (h << 4) + ch; | |
55 | if ((g = (h & 0xf0000000)) != 0) | |
56 | { | |
57 | h ^= g >> 24; | |
58 | h &= ~g; | |
59 | } | |
60 | } | |
61 | return h; | |
62 | } | |
63 | ||
64 | /* Read a specified number of bytes at a specified offset in an ELF | |
65 | file, into a newly allocated buffer, and return a pointer to the | |
66 | buffer. */ | |
67 | ||
68 | static char * | |
013dec1a ILT |
69 | elf_read (abfd, offset, size) |
70 | bfd * abfd; | |
71 | long offset; | |
72 | int size; | |
32090b8e KR |
73 | { |
74 | char *buf; | |
75 | ||
76 | if ((buf = bfd_alloc (abfd, size)) == NULL) | |
77 | { | |
013dec1a | 78 | bfd_set_error (bfd_error_no_memory); |
32090b8e KR |
79 | return NULL; |
80 | } | |
81 | if (bfd_seek (abfd, offset, SEEK_SET) == -1) | |
013dec1a | 82 | return NULL; |
32090b8e KR |
83 | if (bfd_read ((PTR) buf, size, 1, abfd) != size) |
84 | { | |
013dec1a ILT |
85 | if (bfd_get_error () != bfd_error_system_call) |
86 | bfd_set_error (bfd_error_file_truncated); | |
32090b8e KR |
87 | return NULL; |
88 | } | |
89 | return buf; | |
90 | } | |
91 | ||
92 | boolean | |
013dec1a ILT |
93 | elf_mkobject (abfd) |
94 | bfd * abfd; | |
32090b8e KR |
95 | { |
96 | /* this just does initialization */ | |
97 | /* coff_mkobject zalloc's space for tdata.coff_obj_data ... */ | |
98 | elf_tdata (abfd) = (struct elf_obj_tdata *) | |
99 | bfd_zalloc (abfd, sizeof (struct elf_obj_tdata)); | |
100 | if (elf_tdata (abfd) == 0) | |
101 | { | |
013dec1a | 102 | bfd_set_error (bfd_error_no_memory); |
32090b8e KR |
103 | return false; |
104 | } | |
105 | /* since everything is done at close time, do we need any | |
106 | initialization? */ | |
107 | ||
108 | return true; | |
109 | } | |
110 | ||
111 | char * | |
013dec1a ILT |
112 | elf_get_str_section (abfd, shindex) |
113 | bfd * abfd; | |
114 | unsigned int shindex; | |
32090b8e KR |
115 | { |
116 | Elf_Internal_Shdr **i_shdrp; | |
117 | char *shstrtab = NULL; | |
118 | unsigned int offset; | |
119 | unsigned int shstrtabsize; | |
120 | ||
121 | i_shdrp = elf_elfsections (abfd); | |
122 | if (i_shdrp == 0 || i_shdrp[shindex] == 0) | |
123 | return 0; | |
124 | ||
125 | shstrtab = i_shdrp[shindex]->rawdata; | |
126 | if (shstrtab == NULL) | |
127 | { | |
128 | /* No cached one, attempt to read, and cache what we read. */ | |
129 | offset = i_shdrp[shindex]->sh_offset; | |
130 | shstrtabsize = i_shdrp[shindex]->sh_size; | |
131 | shstrtab = elf_read (abfd, offset, shstrtabsize); | |
132 | i_shdrp[shindex]->rawdata = (void *) shstrtab; | |
133 | } | |
134 | return shstrtab; | |
135 | } | |
136 | ||
137 | char * | |
013dec1a ILT |
138 | elf_string_from_elf_section (abfd, shindex, strindex) |
139 | bfd * abfd; | |
140 | unsigned int shindex; | |
141 | unsigned int strindex; | |
32090b8e KR |
142 | { |
143 | Elf_Internal_Shdr *hdr; | |
144 | ||
145 | if (strindex == 0) | |
146 | return ""; | |
147 | ||
148 | hdr = elf_elfsections (abfd)[shindex]; | |
149 | ||
150 | if (!hdr->rawdata | |
151 | && elf_get_str_section (abfd, shindex) == NULL) | |
152 | return NULL; | |
153 | ||
154 | return ((char *) hdr->rawdata) + strindex; | |
155 | } | |
156 | ||
497c5434 ILT |
157 | /* Make a BFD section from an ELF section. We store a pointer to the |
158 | BFD section in the rawdata field of the header. */ | |
159 | ||
160 | boolean | |
161 | _bfd_elf_make_section_from_shdr (abfd, hdr, name) | |
162 | bfd *abfd; | |
163 | Elf_Internal_Shdr *hdr; | |
164 | const char *name; | |
165 | { | |
166 | asection *newsect; | |
167 | flagword flags; | |
168 | ||
169 | if (hdr->rawdata != NULL) | |
170 | { | |
171 | BFD_ASSERT (strcmp (name, ((asection *) hdr->rawdata)->name) == 0); | |
172 | return true; | |
173 | } | |
174 | ||
175 | newsect = bfd_make_section_anyway (abfd, name); | |
176 | if (newsect == NULL) | |
177 | return false; | |
178 | ||
179 | newsect->filepos = hdr->sh_offset; | |
180 | ||
181 | if (! bfd_set_section_vma (abfd, newsect, hdr->sh_addr) | |
182 | || ! bfd_set_section_size (abfd, newsect, hdr->sh_size) | |
183 | || ! bfd_set_section_alignment (abfd, newsect, | |
184 | bfd_log2 (hdr->sh_addralign))) | |
185 | return false; | |
186 | ||
187 | flags = SEC_NO_FLAGS; | |
188 | if (hdr->sh_type != SHT_NOBITS) | |
189 | flags |= SEC_HAS_CONTENTS; | |
190 | if ((hdr->sh_flags & SHF_ALLOC) != 0) | |
191 | { | |
192 | flags |= SEC_ALLOC; | |
193 | if (hdr->sh_type != SHT_NOBITS) | |
194 | flags |= SEC_LOAD; | |
195 | } | |
196 | if ((hdr->sh_flags & SHF_WRITE) == 0) | |
197 | flags |= SEC_READONLY; | |
198 | if ((hdr->sh_flags & SHF_EXECINSTR) != 0) | |
199 | flags |= SEC_CODE; | |
200 | else if ((flags & SEC_ALLOC) != 0) | |
201 | flags |= SEC_DATA; | |
202 | ||
203 | /* The debugging sections appear to be recognized only by name, not | |
204 | any sort of flag. */ | |
205 | if (strncmp (name, ".debug", sizeof ".debug" - 1) == 0 | |
206 | || strncmp (name, ".line", sizeof ".line" - 1) == 0 | |
207 | || strncmp (name, ".stab", sizeof ".stab" - 1) == 0) | |
208 | flags |= SEC_DEBUGGING; | |
209 | ||
210 | if (! bfd_set_section_flags (abfd, newsect, flags)) | |
211 | return false; | |
212 | ||
213 | hdr->rawdata = (PTR) newsect; | |
214 | elf_section_data (newsect)->this_hdr = *hdr; | |
215 | ||
216 | return true; | |
217 | } | |
218 | ||
32090b8e KR |
219 | /* |
220 | INTERNAL_FUNCTION | |
221 | bfd_elf_find_section | |
222 | ||
223 | SYNOPSIS | |
224 | struct elf_internal_shdr *bfd_elf_find_section (bfd *abfd, char *name); | |
225 | ||
226 | DESCRIPTION | |
227 | Helper functions for GDB to locate the string tables. | |
228 | Since BFD hides string tables from callers, GDB needs to use an | |
229 | internal hook to find them. Sun's .stabstr, in particular, | |
230 | isn't even pointed to by the .stab section, so ordinary | |
231 | mechanisms wouldn't work to find it, even if we had some. | |
232 | */ | |
233 | ||
234 | struct elf_internal_shdr * | |
013dec1a ILT |
235 | bfd_elf_find_section (abfd, name) |
236 | bfd * abfd; | |
237 | char *name; | |
32090b8e KR |
238 | { |
239 | Elf_Internal_Shdr **i_shdrp; | |
240 | char *shstrtab; | |
241 | unsigned int max; | |
242 | unsigned int i; | |
243 | ||
244 | i_shdrp = elf_elfsections (abfd); | |
245 | if (i_shdrp != NULL) | |
246 | { | |
247 | shstrtab = elf_get_str_section (abfd, elf_elfheader (abfd)->e_shstrndx); | |
248 | if (shstrtab != NULL) | |
249 | { | |
250 | max = elf_elfheader (abfd)->e_shnum; | |
251 | for (i = 1; i < max; i++) | |
252 | if (!strcmp (&shstrtab[i_shdrp[i]->sh_name], name)) | |
253 | return i_shdrp[i]; | |
254 | } | |
255 | } | |
256 | return 0; | |
257 | } | |
258 | ||
32090b8e KR |
259 | const char *const bfd_elf_section_type_names[] = { |
260 | "SHT_NULL", "SHT_PROGBITS", "SHT_SYMTAB", "SHT_STRTAB", | |
261 | "SHT_RELA", "SHT_HASH", "SHT_DYNAMIC", "SHT_NOTE", | |
262 | "SHT_NOBITS", "SHT_REL", "SHT_SHLIB", "SHT_DYNSYM", | |
263 | }; | |
264 | ||
265 | /* ELF relocs are against symbols. If we are producing relocateable | |
266 | output, and the reloc is against an external symbol, and nothing | |
267 | has given us any additional addend, the resulting reloc will also | |
268 | be against the same symbol. In such a case, we don't want to | |
269 | change anything about the way the reloc is handled, since it will | |
270 | all be done at final link time. Rather than put special case code | |
271 | into bfd_perform_relocation, all the reloc types use this howto | |
272 | function. It just short circuits the reloc if producing | |
273 | relocateable output against an external symbol. */ | |
274 | ||
013dec1a | 275 | /*ARGSUSED*/ |
32090b8e KR |
276 | bfd_reloc_status_type |
277 | bfd_elf_generic_reloc (abfd, | |
278 | reloc_entry, | |
279 | symbol, | |
280 | data, | |
281 | input_section, | |
4c3721d5 ILT |
282 | output_bfd, |
283 | error_message) | |
32090b8e KR |
284 | bfd *abfd; |
285 | arelent *reloc_entry; | |
286 | asymbol *symbol; | |
287 | PTR data; | |
288 | asection *input_section; | |
289 | bfd *output_bfd; | |
4c3721d5 | 290 | char **error_message; |
32090b8e KR |
291 | { |
292 | if (output_bfd != (bfd *) NULL | |
293 | && (symbol->flags & BSF_SECTION_SYM) == 0 | |
d1b44e83 ILT |
294 | && (! reloc_entry->howto->partial_inplace |
295 | || reloc_entry->addend == 0)) | |
32090b8e KR |
296 | { |
297 | reloc_entry->address += input_section->output_offset; | |
298 | return bfd_reloc_ok; | |
299 | } | |
300 | ||
301 | return bfd_reloc_continue; | |
302 | } | |
013dec1a | 303 | \f |
013dec1a ILT |
304 | /* Create an entry in an ELF linker hash table. */ |
305 | ||
5315c428 ILT |
306 | struct bfd_hash_entry * |
307 | _bfd_elf_link_hash_newfunc (entry, table, string) | |
013dec1a ILT |
308 | struct bfd_hash_entry *entry; |
309 | struct bfd_hash_table *table; | |
310 | const char *string; | |
311 | { | |
312 | struct elf_link_hash_entry *ret = (struct elf_link_hash_entry *) entry; | |
313 | ||
314 | /* Allocate the structure if it has not already been allocated by a | |
315 | subclass. */ | |
316 | if (ret == (struct elf_link_hash_entry *) NULL) | |
317 | ret = ((struct elf_link_hash_entry *) | |
318 | bfd_hash_allocate (table, sizeof (struct elf_link_hash_entry))); | |
319 | if (ret == (struct elf_link_hash_entry *) NULL) | |
320 | { | |
321 | bfd_set_error (bfd_error_no_memory); | |
322 | return (struct bfd_hash_entry *) ret; | |
323 | } | |
324 | ||
325 | /* Call the allocation method of the superclass. */ | |
326 | ret = ((struct elf_link_hash_entry *) | |
327 | _bfd_link_hash_newfunc ((struct bfd_hash_entry *) ret, | |
328 | table, string)); | |
329 | if (ret != (struct elf_link_hash_entry *) NULL) | |
330 | { | |
331 | /* Set local fields. */ | |
332 | ret->indx = -1; | |
333 | ret->size = 0; | |
334 | ret->align = 0; | |
335 | ret->dynindx = -1; | |
336 | ret->dynstr_index = 0; | |
337 | ret->weakdef = NULL; | |
338 | ret->type = STT_NOTYPE; | |
339 | ret->elf_link_hash_flags = 0; | |
340 | } | |
341 | ||
342 | return (struct bfd_hash_entry *) ret; | |
343 | } | |
344 | ||
5315c428 ILT |
345 | /* Initialize an ELF linker hash table. */ |
346 | ||
347 | boolean | |
348 | _bfd_elf_link_hash_table_init (table, abfd, newfunc) | |
349 | struct elf_link_hash_table *table; | |
350 | bfd *abfd; | |
351 | struct bfd_hash_entry *(*newfunc) PARAMS ((struct bfd_hash_entry *, | |
352 | struct bfd_hash_table *, | |
353 | const char *)); | |
354 | { | |
355 | table->dynobj = NULL; | |
356 | table->dynsymcount = 0; | |
357 | table->dynstr = NULL; | |
358 | table->bucketcount = 0; | |
359 | return _bfd_link_hash_table_init (&table->root, abfd, newfunc); | |
360 | } | |
361 | ||
013dec1a ILT |
362 | /* Create an ELF linker hash table. */ |
363 | ||
364 | struct bfd_link_hash_table * | |
365 | _bfd_elf_link_hash_table_create (abfd) | |
366 | bfd *abfd; | |
367 | { | |
368 | struct elf_link_hash_table *ret; | |
369 | ||
370 | ret = ((struct elf_link_hash_table *) | |
371 | bfd_alloc (abfd, sizeof (struct elf_link_hash_table))); | |
372 | if (ret == (struct elf_link_hash_table *) NULL) | |
373 | { | |
374 | bfd_set_error (bfd_error_no_memory); | |
375 | return NULL; | |
376 | } | |
5315c428 ILT |
377 | |
378 | if (! _bfd_elf_link_hash_table_init (ret, abfd, _bfd_elf_link_hash_newfunc)) | |
013dec1a ILT |
379 | { |
380 | bfd_release (abfd, ret); | |
381 | return NULL; | |
382 | } | |
383 | ||
013dec1a ILT |
384 | return &ret->root; |
385 | } |