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1 | /* Read ELF (Executable and Linking Format) object files for GDB. | |
2 | ||
3 | Copyright (C) 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, | |
4 | 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 | |
5 | Free Software Foundation, Inc. | |
6 | ||
7 | Written by Fred Fish at Cygnus Support. | |
8 | ||
9 | This file is part of GDB. | |
10 | ||
11 | This program is free software; you can redistribute it and/or modify | |
12 | it under the terms of the GNU General Public License as published by | |
13 | the Free Software Foundation; either version 3 of the License, or | |
14 | (at your option) any later version. | |
15 | ||
16 | This program is distributed in the hope that it will be useful, | |
17 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
18 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
19 | GNU General Public License for more details. | |
20 | ||
21 | You should have received a copy of the GNU General Public License | |
22 | along with this program. If not, see <http://www.gnu.org/licenses/>. */ | |
23 | ||
24 | #include "defs.h" | |
25 | #include "bfd.h" | |
26 | #include "gdb_string.h" | |
27 | #include "elf-bfd.h" | |
28 | #include "elf/common.h" | |
29 | #include "elf/internal.h" | |
30 | #include "elf/mips.h" | |
31 | #include "symtab.h" | |
32 | #include "symfile.h" | |
33 | #include "objfiles.h" | |
34 | #include "buildsym.h" | |
35 | #include "stabsread.h" | |
36 | #include "gdb-stabs.h" | |
37 | #include "complaints.h" | |
38 | #include "demangle.h" | |
39 | #include "psympriv.h" | |
40 | ||
41 | extern void _initialize_elfread (void); | |
42 | ||
43 | /* Forward declaration. */ | |
44 | static const struct sym_fns elf_sym_fns_gdb_index; | |
45 | ||
46 | /* The struct elfinfo is available only during ELF symbol table and | |
47 | psymtab reading. It is destroyed at the completion of psymtab-reading. | |
48 | It's local to elf_symfile_read. */ | |
49 | ||
50 | struct elfinfo | |
51 | { | |
52 | asection *stabsect; /* Section pointer for .stab section */ | |
53 | asection *stabindexsect; /* Section pointer for .stab.index section */ | |
54 | asection *mdebugsect; /* Section pointer for .mdebug section */ | |
55 | }; | |
56 | ||
57 | static void free_elfinfo (void *); | |
58 | ||
59 | /* Locate the segments in ABFD. */ | |
60 | ||
61 | static struct symfile_segment_data * | |
62 | elf_symfile_segments (bfd *abfd) | |
63 | { | |
64 | Elf_Internal_Phdr *phdrs, **segments; | |
65 | long phdrs_size; | |
66 | int num_phdrs, num_segments, num_sections, i; | |
67 | asection *sect; | |
68 | struct symfile_segment_data *data; | |
69 | ||
70 | phdrs_size = bfd_get_elf_phdr_upper_bound (abfd); | |
71 | if (phdrs_size == -1) | |
72 | return NULL; | |
73 | ||
74 | phdrs = alloca (phdrs_size); | |
75 | num_phdrs = bfd_get_elf_phdrs (abfd, phdrs); | |
76 | if (num_phdrs == -1) | |
77 | return NULL; | |
78 | ||
79 | num_segments = 0; | |
80 | segments = alloca (sizeof (Elf_Internal_Phdr *) * num_phdrs); | |
81 | for (i = 0; i < num_phdrs; i++) | |
82 | if (phdrs[i].p_type == PT_LOAD) | |
83 | segments[num_segments++] = &phdrs[i]; | |
84 | ||
85 | if (num_segments == 0) | |
86 | return NULL; | |
87 | ||
88 | data = XZALLOC (struct symfile_segment_data); | |
89 | data->num_segments = num_segments; | |
90 | data->segment_bases = XCALLOC (num_segments, CORE_ADDR); | |
91 | data->segment_sizes = XCALLOC (num_segments, CORE_ADDR); | |
92 | ||
93 | for (i = 0; i < num_segments; i++) | |
94 | { | |
95 | data->segment_bases[i] = segments[i]->p_vaddr; | |
96 | data->segment_sizes[i] = segments[i]->p_memsz; | |
97 | } | |
98 | ||
99 | num_sections = bfd_count_sections (abfd); | |
100 | data->segment_info = XCALLOC (num_sections, int); | |
101 | ||
102 | for (i = 0, sect = abfd->sections; sect != NULL; i++, sect = sect->next) | |
103 | { | |
104 | int j; | |
105 | CORE_ADDR vma; | |
106 | ||
107 | if ((bfd_get_section_flags (abfd, sect) & SEC_ALLOC) == 0) | |
108 | continue; | |
109 | ||
110 | vma = bfd_get_section_vma (abfd, sect); | |
111 | ||
112 | for (j = 0; j < num_segments; j++) | |
113 | if (segments[j]->p_memsz > 0 | |
114 | && vma >= segments[j]->p_vaddr | |
115 | && (vma - segments[j]->p_vaddr) < segments[j]->p_memsz) | |
116 | { | |
117 | data->segment_info[i] = j + 1; | |
118 | break; | |
119 | } | |
120 | ||
121 | /* We should have found a segment for every non-empty section. | |
122 | If we haven't, we will not relocate this section by any | |
123 | offsets we apply to the segments. As an exception, do not | |
124 | warn about SHT_NOBITS sections; in normal ELF execution | |
125 | environments, SHT_NOBITS means zero-initialized and belongs | |
126 | in a segment, but in no-OS environments some tools (e.g. ARM | |
127 | RealView) use SHT_NOBITS for uninitialized data. Since it is | |
128 | uninitialized, it doesn't need a program header. Such | |
129 | binaries are not relocatable. */ | |
130 | if (bfd_get_section_size (sect) > 0 && j == num_segments | |
131 | && (bfd_get_section_flags (abfd, sect) & SEC_LOAD) != 0) | |
132 | warning (_("Loadable segment \"%s\" outside of ELF segments"), | |
133 | bfd_section_name (abfd, sect)); | |
134 | } | |
135 | ||
136 | return data; | |
137 | } | |
138 | ||
139 | /* We are called once per section from elf_symfile_read. We | |
140 | need to examine each section we are passed, check to see | |
141 | if it is something we are interested in processing, and | |
142 | if so, stash away some access information for the section. | |
143 | ||
144 | For now we recognize the dwarf debug information sections and | |
145 | line number sections from matching their section names. The | |
146 | ELF definition is no real help here since it has no direct | |
147 | knowledge of DWARF (by design, so any debugging format can be | |
148 | used). | |
149 | ||
150 | We also recognize the ".stab" sections used by the Sun compilers | |
151 | released with Solaris 2. | |
152 | ||
153 | FIXME: The section names should not be hardwired strings (what | |
154 | should they be? I don't think most object file formats have enough | |
155 | section flags to specify what kind of debug section it is | |
156 | -kingdon). */ | |
157 | ||
158 | static void | |
159 | elf_locate_sections (bfd *ignore_abfd, asection *sectp, void *eip) | |
160 | { | |
161 | struct elfinfo *ei; | |
162 | ||
163 | ei = (struct elfinfo *) eip; | |
164 | if (strcmp (sectp->name, ".stab") == 0) | |
165 | { | |
166 | ei->stabsect = sectp; | |
167 | } | |
168 | else if (strcmp (sectp->name, ".stab.index") == 0) | |
169 | { | |
170 | ei->stabindexsect = sectp; | |
171 | } | |
172 | else if (strcmp (sectp->name, ".mdebug") == 0) | |
173 | { | |
174 | ei->mdebugsect = sectp; | |
175 | } | |
176 | } | |
177 | ||
178 | static struct minimal_symbol * | |
179 | record_minimal_symbol (const char *name, int name_len, int copy_name, | |
180 | CORE_ADDR address, | |
181 | enum minimal_symbol_type ms_type, | |
182 | asection *bfd_section, struct objfile *objfile) | |
183 | { | |
184 | struct gdbarch *gdbarch = get_objfile_arch (objfile); | |
185 | ||
186 | if (ms_type == mst_text || ms_type == mst_file_text) | |
187 | address = gdbarch_smash_text_address (gdbarch, address); | |
188 | ||
189 | return prim_record_minimal_symbol_full (name, name_len, copy_name, address, | |
190 | ms_type, bfd_section->index, | |
191 | bfd_section, objfile); | |
192 | } | |
193 | ||
194 | /* | |
195 | ||
196 | LOCAL FUNCTION | |
197 | ||
198 | elf_symtab_read -- read the symbol table of an ELF file | |
199 | ||
200 | SYNOPSIS | |
201 | ||
202 | void elf_symtab_read (struct objfile *objfile, int type, | |
203 | long number_of_symbols, asymbol **symbol_table) | |
204 | ||
205 | DESCRIPTION | |
206 | ||
207 | Given an objfile, a symbol table, and a flag indicating whether the | |
208 | symbol table contains regular, dynamic, or synthetic symbols, add all | |
209 | the global function and data symbols to the minimal symbol table. | |
210 | ||
211 | In stabs-in-ELF, as implemented by Sun, there are some local symbols | |
212 | defined in the ELF symbol table, which can be used to locate | |
213 | the beginnings of sections from each ".o" file that was linked to | |
214 | form the executable objfile. We gather any such info and record it | |
215 | in data structures hung off the objfile's private data. | |
216 | ||
217 | */ | |
218 | ||
219 | #define ST_REGULAR 0 | |
220 | #define ST_DYNAMIC 1 | |
221 | #define ST_SYNTHETIC 2 | |
222 | ||
223 | static void | |
224 | elf_symtab_read (struct objfile *objfile, int type, | |
225 | long number_of_symbols, asymbol **symbol_table, | |
226 | int copy_names) | |
227 | { | |
228 | struct gdbarch *gdbarch = get_objfile_arch (objfile); | |
229 | asymbol *sym; | |
230 | long i; | |
231 | CORE_ADDR symaddr; | |
232 | CORE_ADDR offset; | |
233 | enum minimal_symbol_type ms_type; | |
234 | /* If sectinfo is nonNULL, it contains section info that should end up | |
235 | filed in the objfile. */ | |
236 | struct stab_section_info *sectinfo = NULL; | |
237 | /* If filesym is nonzero, it points to a file symbol, but we haven't | |
238 | seen any section info for it yet. */ | |
239 | asymbol *filesym = 0; | |
240 | /* Name of filesym. This is either a constant string or is saved on | |
241 | the objfile's obstack. */ | |
242 | char *filesymname = ""; | |
243 | struct dbx_symfile_info *dbx = objfile->deprecated_sym_stab_info; | |
244 | int stripped = (bfd_get_symcount (objfile->obfd) == 0); | |
245 | ||
246 | for (i = 0; i < number_of_symbols; i++) | |
247 | { | |
248 | sym = symbol_table[i]; | |
249 | if (sym->name == NULL || *sym->name == '\0') | |
250 | { | |
251 | /* Skip names that don't exist (shouldn't happen), or names | |
252 | that are null strings (may happen). */ | |
253 | continue; | |
254 | } | |
255 | ||
256 | /* Skip "special" symbols, e.g. ARM mapping symbols. These are | |
257 | symbols which do not correspond to objects in the symbol table, | |
258 | but have some other target-specific meaning. */ | |
259 | if (bfd_is_target_special_symbol (objfile->obfd, sym)) | |
260 | { | |
261 | if (gdbarch_record_special_symbol_p (gdbarch)) | |
262 | gdbarch_record_special_symbol (gdbarch, objfile, sym); | |
263 | continue; | |
264 | } | |
265 | ||
266 | offset = ANOFFSET (objfile->section_offsets, sym->section->index); | |
267 | if (type == ST_DYNAMIC | |
268 | && sym->section == &bfd_und_section | |
269 | && (sym->flags & BSF_FUNCTION)) | |
270 | { | |
271 | struct minimal_symbol *msym; | |
272 | bfd *abfd = objfile->obfd; | |
273 | asection *sect; | |
274 | ||
275 | /* Symbol is a reference to a function defined in | |
276 | a shared library. | |
277 | If its value is non zero then it is usually the address | |
278 | of the corresponding entry in the procedure linkage table, | |
279 | plus the desired section offset. | |
280 | If its value is zero then the dynamic linker has to resolve | |
281 | the symbol. We are unable to find any meaningful address | |
282 | for this symbol in the executable file, so we skip it. */ | |
283 | symaddr = sym->value; | |
284 | if (symaddr == 0) | |
285 | continue; | |
286 | ||
287 | /* sym->section is the undefined section. However, we want to | |
288 | record the section where the PLT stub resides with the | |
289 | minimal symbol. Search the section table for the one that | |
290 | covers the stub's address. */ | |
291 | for (sect = abfd->sections; sect != NULL; sect = sect->next) | |
292 | { | |
293 | if ((bfd_get_section_flags (abfd, sect) & SEC_ALLOC) == 0) | |
294 | continue; | |
295 | ||
296 | if (symaddr >= bfd_get_section_vma (abfd, sect) | |
297 | && symaddr < bfd_get_section_vma (abfd, sect) | |
298 | + bfd_get_section_size (sect)) | |
299 | break; | |
300 | } | |
301 | if (!sect) | |
302 | continue; | |
303 | ||
304 | symaddr += ANOFFSET (objfile->section_offsets, sect->index); | |
305 | ||
306 | msym = record_minimal_symbol | |
307 | (sym->name, strlen (sym->name), copy_names, | |
308 | symaddr, mst_solib_trampoline, sect, objfile); | |
309 | if (msym != NULL) | |
310 | msym->filename = filesymname; | |
311 | continue; | |
312 | } | |
313 | ||
314 | /* If it is a nonstripped executable, do not enter dynamic | |
315 | symbols, as the dynamic symbol table is usually a subset | |
316 | of the main symbol table. */ | |
317 | if (type == ST_DYNAMIC && !stripped) | |
318 | continue; | |
319 | if (sym->flags & BSF_FILE) | |
320 | { | |
321 | /* STT_FILE debugging symbol that helps stabs-in-elf debugging. | |
322 | Chain any old one onto the objfile; remember new sym. */ | |
323 | if (sectinfo != NULL) | |
324 | { | |
325 | sectinfo->next = dbx->stab_section_info; | |
326 | dbx->stab_section_info = sectinfo; | |
327 | sectinfo = NULL; | |
328 | } | |
329 | filesym = sym; | |
330 | filesymname = | |
331 | obsavestring ((char *) filesym->name, strlen (filesym->name), | |
332 | &objfile->objfile_obstack); | |
333 | } | |
334 | else if (sym->flags & BSF_SECTION_SYM) | |
335 | continue; | |
336 | else if (sym->flags & (BSF_GLOBAL | BSF_LOCAL | BSF_WEAK)) | |
337 | { | |
338 | struct minimal_symbol *msym; | |
339 | ||
340 | /* Select global/local/weak symbols. Note that bfd puts abs | |
341 | symbols in their own section, so all symbols we are | |
342 | interested in will have a section. */ | |
343 | /* Bfd symbols are section relative. */ | |
344 | symaddr = sym->value + sym->section->vma; | |
345 | /* Relocate all non-absolute and non-TLS symbols by the | |
346 | section offset. */ | |
347 | if (sym->section != &bfd_abs_section | |
348 | && !(sym->section->flags & SEC_THREAD_LOCAL)) | |
349 | { | |
350 | symaddr += offset; | |
351 | } | |
352 | /* For non-absolute symbols, use the type of the section | |
353 | they are relative to, to intuit text/data. Bfd provides | |
354 | no way of figuring this out for absolute symbols. */ | |
355 | if (sym->section == &bfd_abs_section) | |
356 | { | |
357 | /* This is a hack to get the minimal symbol type | |
358 | right for Irix 5, which has absolute addresses | |
359 | with special section indices for dynamic symbols. | |
360 | ||
361 | NOTE: uweigand-20071112: Synthetic symbols do not | |
362 | have an ELF-private part, so do not touch those. */ | |
363 | unsigned int shndx = type == ST_SYNTHETIC ? 0 : | |
364 | ((elf_symbol_type *) sym)->internal_elf_sym.st_shndx; | |
365 | ||
366 | switch (shndx) | |
367 | { | |
368 | case SHN_MIPS_TEXT: | |
369 | ms_type = mst_text; | |
370 | break; | |
371 | case SHN_MIPS_DATA: | |
372 | ms_type = mst_data; | |
373 | break; | |
374 | case SHN_MIPS_ACOMMON: | |
375 | ms_type = mst_bss; | |
376 | break; | |
377 | default: | |
378 | ms_type = mst_abs; | |
379 | } | |
380 | ||
381 | /* If it is an Irix dynamic symbol, skip section name | |
382 | symbols, relocate all others by section offset. */ | |
383 | if (ms_type != mst_abs) | |
384 | { | |
385 | if (sym->name[0] == '.') | |
386 | continue; | |
387 | symaddr += offset; | |
388 | } | |
389 | } | |
390 | else if (sym->section->flags & SEC_CODE) | |
391 | { | |
392 | if (sym->flags & (BSF_GLOBAL | BSF_WEAK)) | |
393 | { | |
394 | ms_type = mst_text; | |
395 | } | |
396 | else if ((sym->name[0] == '.' && sym->name[1] == 'L') | |
397 | || ((sym->flags & BSF_LOCAL) | |
398 | && sym->name[0] == '$' | |
399 | && sym->name[1] == 'L')) | |
400 | /* Looks like a compiler-generated label. Skip | |
401 | it. The assembler should be skipping these (to | |
402 | keep executables small), but apparently with | |
403 | gcc on the (deleted) delta m88k SVR4, it loses. | |
404 | So to have us check too should be harmless (but | |
405 | I encourage people to fix this in the assembler | |
406 | instead of adding checks here). */ | |
407 | continue; | |
408 | else | |
409 | { | |
410 | ms_type = mst_file_text; | |
411 | } | |
412 | } | |
413 | else if (sym->section->flags & SEC_ALLOC) | |
414 | { | |
415 | if (sym->flags & (BSF_GLOBAL | BSF_WEAK)) | |
416 | { | |
417 | if (sym->section->flags & SEC_LOAD) | |
418 | { | |
419 | ms_type = mst_data; | |
420 | } | |
421 | else | |
422 | { | |
423 | ms_type = mst_bss; | |
424 | } | |
425 | } | |
426 | else if (sym->flags & BSF_LOCAL) | |
427 | { | |
428 | /* Named Local variable in a Data section. | |
429 | Check its name for stabs-in-elf. */ | |
430 | int special_local_sect; | |
431 | ||
432 | if (strcmp ("Bbss.bss", sym->name) == 0) | |
433 | special_local_sect = SECT_OFF_BSS (objfile); | |
434 | else if (strcmp ("Ddata.data", sym->name) == 0) | |
435 | special_local_sect = SECT_OFF_DATA (objfile); | |
436 | else if (strcmp ("Drodata.rodata", sym->name) == 0) | |
437 | special_local_sect = SECT_OFF_RODATA (objfile); | |
438 | else | |
439 | special_local_sect = -1; | |
440 | if (special_local_sect >= 0) | |
441 | { | |
442 | /* Found a special local symbol. Allocate a | |
443 | sectinfo, if needed, and fill it in. */ | |
444 | if (sectinfo == NULL) | |
445 | { | |
446 | int max_index; | |
447 | size_t size; | |
448 | ||
449 | max_index = SECT_OFF_BSS (objfile); | |
450 | if (objfile->sect_index_data > max_index) | |
451 | max_index = objfile->sect_index_data; | |
452 | if (objfile->sect_index_rodata > max_index) | |
453 | max_index = objfile->sect_index_rodata; | |
454 | ||
455 | /* max_index is the largest index we'll | |
456 | use into this array, so we must | |
457 | allocate max_index+1 elements for it. | |
458 | However, 'struct stab_section_info' | |
459 | already includes one element, so we | |
460 | need to allocate max_index aadditional | |
461 | elements. */ | |
462 | size = (sizeof (struct stab_section_info) | |
463 | + (sizeof (CORE_ADDR) | |
464 | * max_index)); | |
465 | sectinfo = (struct stab_section_info *) | |
466 | xmalloc (size); | |
467 | memset (sectinfo, 0, size); | |
468 | sectinfo->num_sections = max_index; | |
469 | if (filesym == NULL) | |
470 | { | |
471 | complaint (&symfile_complaints, | |
472 | _("elf/stab section information %s " | |
473 | "without a preceding file symbol"), | |
474 | sym->name); | |
475 | } | |
476 | else | |
477 | { | |
478 | sectinfo->filename = | |
479 | (char *) filesym->name; | |
480 | } | |
481 | } | |
482 | if (sectinfo->sections[special_local_sect] != 0) | |
483 | complaint (&symfile_complaints, | |
484 | _("duplicated elf/stab section " | |
485 | "information for %s"), | |
486 | sectinfo->filename); | |
487 | /* BFD symbols are section relative. */ | |
488 | symaddr = sym->value + sym->section->vma; | |
489 | /* Relocate non-absolute symbols by the | |
490 | section offset. */ | |
491 | if (sym->section != &bfd_abs_section) | |
492 | symaddr += offset; | |
493 | sectinfo->sections[special_local_sect] = symaddr; | |
494 | /* The special local symbols don't go in the | |
495 | minimal symbol table, so ignore this one. */ | |
496 | continue; | |
497 | } | |
498 | /* Not a special stabs-in-elf symbol, do regular | |
499 | symbol processing. */ | |
500 | if (sym->section->flags & SEC_LOAD) | |
501 | { | |
502 | ms_type = mst_file_data; | |
503 | } | |
504 | else | |
505 | { | |
506 | ms_type = mst_file_bss; | |
507 | } | |
508 | } | |
509 | else | |
510 | { | |
511 | ms_type = mst_unknown; | |
512 | } | |
513 | } | |
514 | else | |
515 | { | |
516 | /* FIXME: Solaris2 shared libraries include lots of | |
517 | odd "absolute" and "undefined" symbols, that play | |
518 | hob with actions like finding what function the PC | |
519 | is in. Ignore them if they aren't text, data, or bss. */ | |
520 | /* ms_type = mst_unknown; */ | |
521 | continue; /* Skip this symbol. */ | |
522 | } | |
523 | msym = record_minimal_symbol | |
524 | (sym->name, strlen (sym->name), copy_names, symaddr, | |
525 | ms_type, sym->section, objfile); | |
526 | ||
527 | if (msym) | |
528 | { | |
529 | /* Pass symbol size field in via BFD. FIXME!!! */ | |
530 | elf_symbol_type *elf_sym; | |
531 | ||
532 | /* NOTE: uweigand-20071112: A synthetic symbol does not have an | |
533 | ELF-private part. However, in some cases (e.g. synthetic | |
534 | 'dot' symbols on ppc64) the udata.p entry is set to point back | |
535 | to the original ELF symbol it was derived from. Get the size | |
536 | from that symbol. */ | |
537 | if (type != ST_SYNTHETIC) | |
538 | elf_sym = (elf_symbol_type *) sym; | |
539 | else | |
540 | elf_sym = (elf_symbol_type *) sym->udata.p; | |
541 | ||
542 | if (elf_sym) | |
543 | MSYMBOL_SIZE(msym) = elf_sym->internal_elf_sym.st_size; | |
544 | ||
545 | msym->filename = filesymname; | |
546 | gdbarch_elf_make_msymbol_special (gdbarch, sym, msym); | |
547 | } | |
548 | ||
549 | /* For @plt symbols, also record a trampoline to the | |
550 | destination symbol. The @plt symbol will be used in | |
551 | disassembly, and the trampoline will be used when we are | |
552 | trying to find the target. */ | |
553 | if (msym && ms_type == mst_text && type == ST_SYNTHETIC) | |
554 | { | |
555 | int len = strlen (sym->name); | |
556 | ||
557 | if (len > 4 && strcmp (sym->name + len - 4, "@plt") == 0) | |
558 | { | |
559 | struct minimal_symbol *mtramp; | |
560 | ||
561 | mtramp = record_minimal_symbol (sym->name, len - 4, 1, | |
562 | symaddr, | |
563 | mst_solib_trampoline, | |
564 | sym->section, objfile); | |
565 | if (mtramp) | |
566 | { | |
567 | MSYMBOL_SIZE (mtramp) = MSYMBOL_SIZE (msym); | |
568 | mtramp->filename = filesymname; | |
569 | gdbarch_elf_make_msymbol_special (gdbarch, sym, mtramp); | |
570 | } | |
571 | } | |
572 | } | |
573 | } | |
574 | } | |
575 | } | |
576 | ||
577 | struct build_id | |
578 | { | |
579 | size_t size; | |
580 | gdb_byte data[1]; | |
581 | }; | |
582 | ||
583 | /* Locate NT_GNU_BUILD_ID from ABFD and return its content. */ | |
584 | ||
585 | static struct build_id * | |
586 | build_id_bfd_get (bfd *abfd) | |
587 | { | |
588 | struct build_id *retval; | |
589 | ||
590 | if (!bfd_check_format (abfd, bfd_object) | |
591 | || bfd_get_flavour (abfd) != bfd_target_elf_flavour | |
592 | || elf_tdata (abfd)->build_id == NULL) | |
593 | return NULL; | |
594 | ||
595 | retval = xmalloc (sizeof *retval - 1 + elf_tdata (abfd)->build_id_size); | |
596 | retval->size = elf_tdata (abfd)->build_id_size; | |
597 | memcpy (retval->data, elf_tdata (abfd)->build_id, retval->size); | |
598 | ||
599 | return retval; | |
600 | } | |
601 | ||
602 | /* Return if FILENAME has NT_GNU_BUILD_ID matching the CHECK value. */ | |
603 | ||
604 | static int | |
605 | build_id_verify (const char *filename, struct build_id *check) | |
606 | { | |
607 | bfd *abfd; | |
608 | struct build_id *found = NULL; | |
609 | int retval = 0; | |
610 | ||
611 | /* We expect to be silent on the non-existing files. */ | |
612 | abfd = bfd_open_maybe_remote (filename); | |
613 | if (abfd == NULL) | |
614 | return 0; | |
615 | ||
616 | found = build_id_bfd_get (abfd); | |
617 | ||
618 | if (found == NULL) | |
619 | warning (_("File \"%s\" has no build-id, file skipped"), filename); | |
620 | else if (found->size != check->size | |
621 | || memcmp (found->data, check->data, found->size) != 0) | |
622 | warning (_("File \"%s\" has a different build-id, file skipped"), | |
623 | filename); | |
624 | else | |
625 | retval = 1; | |
626 | ||
627 | gdb_bfd_close_or_warn (abfd); | |
628 | ||
629 | xfree (found); | |
630 | ||
631 | return retval; | |
632 | } | |
633 | ||
634 | static char * | |
635 | build_id_to_debug_filename (struct build_id *build_id) | |
636 | { | |
637 | char *link, *debugdir, *retval = NULL; | |
638 | ||
639 | /* DEBUG_FILE_DIRECTORY/.build-id/ab/cdef */ | |
640 | link = alloca (strlen (debug_file_directory) + (sizeof "/.build-id/" - 1) + 1 | |
641 | + 2 * build_id->size + (sizeof ".debug" - 1) + 1); | |
642 | ||
643 | /* Keep backward compatibility so that DEBUG_FILE_DIRECTORY being "" will | |
644 | cause "/.build-id/..." lookups. */ | |
645 | ||
646 | debugdir = debug_file_directory; | |
647 | do | |
648 | { | |
649 | char *s, *debugdir_end; | |
650 | gdb_byte *data = build_id->data; | |
651 | size_t size = build_id->size; | |
652 | ||
653 | while (*debugdir == DIRNAME_SEPARATOR) | |
654 | debugdir++; | |
655 | ||
656 | debugdir_end = strchr (debugdir, DIRNAME_SEPARATOR); | |
657 | if (debugdir_end == NULL) | |
658 | debugdir_end = &debugdir[strlen (debugdir)]; | |
659 | ||
660 | memcpy (link, debugdir, debugdir_end - debugdir); | |
661 | s = &link[debugdir_end - debugdir]; | |
662 | s += sprintf (s, "/.build-id/"); | |
663 | if (size > 0) | |
664 | { | |
665 | size--; | |
666 | s += sprintf (s, "%02x", (unsigned) *data++); | |
667 | } | |
668 | if (size > 0) | |
669 | *s++ = '/'; | |
670 | while (size-- > 0) | |
671 | s += sprintf (s, "%02x", (unsigned) *data++); | |
672 | strcpy (s, ".debug"); | |
673 | ||
674 | /* lrealpath() is expensive even for the usually non-existent files. */ | |
675 | if (access (link, F_OK) == 0) | |
676 | retval = lrealpath (link); | |
677 | ||
678 | if (retval != NULL && !build_id_verify (retval, build_id)) | |
679 | { | |
680 | xfree (retval); | |
681 | retval = NULL; | |
682 | } | |
683 | ||
684 | if (retval != NULL) | |
685 | break; | |
686 | ||
687 | debugdir = debugdir_end; | |
688 | } | |
689 | while (*debugdir != 0); | |
690 | ||
691 | return retval; | |
692 | } | |
693 | ||
694 | static char * | |
695 | find_separate_debug_file_by_buildid (struct objfile *objfile) | |
696 | { | |
697 | struct build_id *build_id; | |
698 | ||
699 | build_id = build_id_bfd_get (objfile->obfd); | |
700 | if (build_id != NULL) | |
701 | { | |
702 | char *build_id_name; | |
703 | ||
704 | build_id_name = build_id_to_debug_filename (build_id); | |
705 | xfree (build_id); | |
706 | /* Prevent looping on a stripped .debug file. */ | |
707 | if (build_id_name != NULL && strcmp (build_id_name, objfile->name) == 0) | |
708 | { | |
709 | warning (_("\"%s\": separate debug info file has no debug info"), | |
710 | build_id_name); | |
711 | xfree (build_id_name); | |
712 | } | |
713 | else if (build_id_name != NULL) | |
714 | return build_id_name; | |
715 | } | |
716 | return NULL; | |
717 | } | |
718 | ||
719 | /* Scan and build partial symbols for a symbol file. | |
720 | We have been initialized by a call to elf_symfile_init, which | |
721 | currently does nothing. | |
722 | ||
723 | SECTION_OFFSETS is a set of offsets to apply to relocate the symbols | |
724 | in each section. We simplify it down to a single offset for all | |
725 | symbols. FIXME. | |
726 | ||
727 | This function only does the minimum work necessary for letting the | |
728 | user "name" things symbolically; it does not read the entire symtab. | |
729 | Instead, it reads the external and static symbols and puts them in partial | |
730 | symbol tables. When more extensive information is requested of a | |
731 | file, the corresponding partial symbol table is mutated into a full | |
732 | fledged symbol table by going back and reading the symbols | |
733 | for real. | |
734 | ||
735 | We look for sections with specific names, to tell us what debug | |
736 | format to look for: FIXME!!! | |
737 | ||
738 | elfstab_build_psymtabs() handles STABS symbols; | |
739 | mdebug_build_psymtabs() handles ECOFF debugging information. | |
740 | ||
741 | Note that ELF files have a "minimal" symbol table, which looks a lot | |
742 | like a COFF symbol table, but has only the minimal information necessary | |
743 | for linking. We process this also, and use the information to | |
744 | build gdb's minimal symbol table. This gives us some minimal debugging | |
745 | capability even for files compiled without -g. */ | |
746 | ||
747 | static void | |
748 | elf_symfile_read (struct objfile *objfile, int symfile_flags) | |
749 | { | |
750 | bfd *abfd = objfile->obfd; | |
751 | struct elfinfo ei; | |
752 | struct cleanup *back_to; | |
753 | long symcount = 0, dynsymcount = 0, synthcount, storage_needed; | |
754 | asymbol **symbol_table = NULL, **dyn_symbol_table = NULL; | |
755 | asymbol *synthsyms; | |
756 | ||
757 | init_minimal_symbol_collection (); | |
758 | back_to = make_cleanup_discard_minimal_symbols (); | |
759 | ||
760 | memset ((char *) &ei, 0, sizeof (ei)); | |
761 | ||
762 | /* Allocate struct to keep track of the symfile */ | |
763 | objfile->deprecated_sym_stab_info = (struct dbx_symfile_info *) | |
764 | xmalloc (sizeof (struct dbx_symfile_info)); | |
765 | memset ((char *) objfile->deprecated_sym_stab_info, | |
766 | 0, sizeof (struct dbx_symfile_info)); | |
767 | make_cleanup (free_elfinfo, (void *) objfile); | |
768 | ||
769 | /* Process the normal ELF symbol table first. This may write some | |
770 | chain of info into the dbx_symfile_info in | |
771 | objfile->deprecated_sym_stab_info, which can later be used by | |
772 | elfstab_offset_sections. */ | |
773 | ||
774 | storage_needed = bfd_get_symtab_upper_bound (objfile->obfd); | |
775 | if (storage_needed < 0) | |
776 | error (_("Can't read symbols from %s: %s"), | |
777 | bfd_get_filename (objfile->obfd), | |
778 | bfd_errmsg (bfd_get_error ())); | |
779 | ||
780 | if (storage_needed > 0) | |
781 | { | |
782 | symbol_table = (asymbol **) xmalloc (storage_needed); | |
783 | make_cleanup (xfree, symbol_table); | |
784 | symcount = bfd_canonicalize_symtab (objfile->obfd, symbol_table); | |
785 | ||
786 | if (symcount < 0) | |
787 | error (_("Can't read symbols from %s: %s"), | |
788 | bfd_get_filename (objfile->obfd), | |
789 | bfd_errmsg (bfd_get_error ())); | |
790 | ||
791 | elf_symtab_read (objfile, ST_REGULAR, symcount, symbol_table, 0); | |
792 | } | |
793 | ||
794 | /* Add the dynamic symbols. */ | |
795 | ||
796 | storage_needed = bfd_get_dynamic_symtab_upper_bound (objfile->obfd); | |
797 | ||
798 | if (storage_needed > 0) | |
799 | { | |
800 | /* Memory gets permanently referenced from ABFD after | |
801 | bfd_get_synthetic_symtab so it must not get freed before ABFD gets. | |
802 | It happens only in the case when elf_slurp_reloc_table sees | |
803 | asection->relocation NULL. Determining which section is asection is | |
804 | done by _bfd_elf_get_synthetic_symtab which is all a bfd | |
805 | implementation detail, though. */ | |
806 | ||
807 | dyn_symbol_table = bfd_alloc (abfd, storage_needed); | |
808 | dynsymcount = bfd_canonicalize_dynamic_symtab (objfile->obfd, | |
809 | dyn_symbol_table); | |
810 | ||
811 | if (dynsymcount < 0) | |
812 | error (_("Can't read symbols from %s: %s"), | |
813 | bfd_get_filename (objfile->obfd), | |
814 | bfd_errmsg (bfd_get_error ())); | |
815 | ||
816 | elf_symtab_read (objfile, ST_DYNAMIC, dynsymcount, dyn_symbol_table, 0); | |
817 | } | |
818 | ||
819 | /* Add synthetic symbols - for instance, names for any PLT entries. */ | |
820 | ||
821 | synthcount = bfd_get_synthetic_symtab (abfd, symcount, symbol_table, | |
822 | dynsymcount, dyn_symbol_table, | |
823 | &synthsyms); | |
824 | if (synthcount > 0) | |
825 | { | |
826 | asymbol **synth_symbol_table; | |
827 | long i; | |
828 | ||
829 | make_cleanup (xfree, synthsyms); | |
830 | synth_symbol_table = xmalloc (sizeof (asymbol *) * synthcount); | |
831 | for (i = 0; i < synthcount; i++) | |
832 | synth_symbol_table[i] = synthsyms + i; | |
833 | make_cleanup (xfree, synth_symbol_table); | |
834 | elf_symtab_read (objfile, ST_SYNTHETIC, synthcount, | |
835 | synth_symbol_table, 1); | |
836 | } | |
837 | ||
838 | /* Install any minimal symbols that have been collected as the current | |
839 | minimal symbols for this objfile. The debug readers below this point | |
840 | should not generate new minimal symbols; if they do it's their | |
841 | responsibility to install them. "mdebug" appears to be the only one | |
842 | which will do this. */ | |
843 | ||
844 | install_minimal_symbols (objfile); | |
845 | do_cleanups (back_to); | |
846 | ||
847 | /* Now process debugging information, which is contained in | |
848 | special ELF sections. */ | |
849 | ||
850 | /* We first have to find them... */ | |
851 | bfd_map_over_sections (abfd, elf_locate_sections, (void *) & ei); | |
852 | ||
853 | /* ELF debugging information is inserted into the psymtab in the | |
854 | order of least informative first - most informative last. Since | |
855 | the psymtab table is searched `most recent insertion first' this | |
856 | increases the probability that more detailed debug information | |
857 | for a section is found. | |
858 | ||
859 | For instance, an object file might contain both .mdebug (XCOFF) | |
860 | and .debug_info (DWARF2) sections then .mdebug is inserted first | |
861 | (searched last) and DWARF2 is inserted last (searched first). If | |
862 | we don't do this then the XCOFF info is found first - for code in | |
863 | an included file XCOFF info is useless. */ | |
864 | ||
865 | if (ei.mdebugsect) | |
866 | { | |
867 | const struct ecoff_debug_swap *swap; | |
868 | ||
869 | /* .mdebug section, presumably holding ECOFF debugging | |
870 | information. */ | |
871 | swap = get_elf_backend_data (abfd)->elf_backend_ecoff_debug_swap; | |
872 | if (swap) | |
873 | elfmdebug_build_psymtabs (objfile, swap, ei.mdebugsect); | |
874 | } | |
875 | if (ei.stabsect) | |
876 | { | |
877 | asection *str_sect; | |
878 | ||
879 | /* Stab sections have an associated string table that looks like | |
880 | a separate section. */ | |
881 | str_sect = bfd_get_section_by_name (abfd, ".stabstr"); | |
882 | ||
883 | /* FIXME should probably warn about a stab section without a stabstr. */ | |
884 | if (str_sect) | |
885 | elfstab_build_psymtabs (objfile, | |
886 | ei.stabsect, | |
887 | str_sect->filepos, | |
888 | bfd_section_size (abfd, str_sect)); | |
889 | } | |
890 | ||
891 | if (dwarf2_has_info (objfile) && dwarf2_initialize_objfile (objfile)) | |
892 | objfile->sf = &elf_sym_fns_gdb_index; | |
893 | ||
894 | /* If the file has its own symbol tables it has no separate debug | |
895 | info. `.dynsym'/`.symtab' go to MSYMBOLS, `.debug_info' goes to | |
896 | SYMTABS/PSYMTABS. `.gnu_debuglink' may no longer be present with | |
897 | `.note.gnu.build-id'. */ | |
898 | if (!objfile_has_partial_symbols (objfile)) | |
899 | { | |
900 | char *debugfile; | |
901 | ||
902 | debugfile = find_separate_debug_file_by_buildid (objfile); | |
903 | ||
904 | if (debugfile == NULL) | |
905 | debugfile = find_separate_debug_file_by_debuglink (objfile); | |
906 | ||
907 | if (debugfile) | |
908 | { | |
909 | bfd *abfd = symfile_bfd_open (debugfile); | |
910 | ||
911 | symbol_file_add_separate (abfd, symfile_flags, objfile); | |
912 | xfree (debugfile); | |
913 | } | |
914 | } | |
915 | } | |
916 | ||
917 | /* This cleans up the objfile's deprecated_sym_stab_info pointer, and | |
918 | the chain of stab_section_info's, that might be dangling from | |
919 | it. */ | |
920 | ||
921 | static void | |
922 | free_elfinfo (void *objp) | |
923 | { | |
924 | struct objfile *objfile = (struct objfile *) objp; | |
925 | struct dbx_symfile_info *dbxinfo = objfile->deprecated_sym_stab_info; | |
926 | struct stab_section_info *ssi, *nssi; | |
927 | ||
928 | ssi = dbxinfo->stab_section_info; | |
929 | while (ssi) | |
930 | { | |
931 | nssi = ssi->next; | |
932 | xfree (ssi); | |
933 | ssi = nssi; | |
934 | } | |
935 | ||
936 | dbxinfo->stab_section_info = 0; /* Just say No mo info about this. */ | |
937 | } | |
938 | ||
939 | ||
940 | /* Initialize anything that needs initializing when a completely new symbol | |
941 | file is specified (not just adding some symbols from another file, e.g. a | |
942 | shared library). | |
943 | ||
944 | We reinitialize buildsym, since we may be reading stabs from an ELF | |
945 | file. */ | |
946 | ||
947 | static void | |
948 | elf_new_init (struct objfile *ignore) | |
949 | { | |
950 | stabsread_new_init (); | |
951 | buildsym_new_init (); | |
952 | } | |
953 | ||
954 | /* Perform any local cleanups required when we are done with a particular | |
955 | objfile. I.E, we are in the process of discarding all symbol information | |
956 | for an objfile, freeing up all memory held for it, and unlinking the | |
957 | objfile struct from the global list of known objfiles. */ | |
958 | ||
959 | static void | |
960 | elf_symfile_finish (struct objfile *objfile) | |
961 | { | |
962 | if (objfile->deprecated_sym_stab_info != NULL) | |
963 | { | |
964 | xfree (objfile->deprecated_sym_stab_info); | |
965 | } | |
966 | ||
967 | dwarf2_free_objfile (objfile); | |
968 | } | |
969 | ||
970 | /* ELF specific initialization routine for reading symbols. | |
971 | ||
972 | It is passed a pointer to a struct sym_fns which contains, among other | |
973 | things, the BFD for the file whose symbols are being read, and a slot for | |
974 | a pointer to "private data" which we can fill with goodies. | |
975 | ||
976 | For now at least, we have nothing in particular to do, so this function is | |
977 | just a stub. */ | |
978 | ||
979 | static void | |
980 | elf_symfile_init (struct objfile *objfile) | |
981 | { | |
982 | /* ELF objects may be reordered, so set OBJF_REORDERED. If we | |
983 | find this causes a significant slowdown in gdb then we could | |
984 | set it in the debug symbol readers only when necessary. */ | |
985 | objfile->flags |= OBJF_REORDERED; | |
986 | } | |
987 | ||
988 | /* When handling an ELF file that contains Sun STABS debug info, | |
989 | some of the debug info is relative to the particular chunk of the | |
990 | section that was generated in its individual .o file. E.g. | |
991 | offsets to static variables are relative to the start of the data | |
992 | segment *for that module before linking*. This information is | |
993 | painfully squirreled away in the ELF symbol table as local symbols | |
994 | with wierd names. Go get 'em when needed. */ | |
995 | ||
996 | void | |
997 | elfstab_offset_sections (struct objfile *objfile, struct partial_symtab *pst) | |
998 | { | |
999 | const char *filename = pst->filename; | |
1000 | struct dbx_symfile_info *dbx = objfile->deprecated_sym_stab_info; | |
1001 | struct stab_section_info *maybe = dbx->stab_section_info; | |
1002 | struct stab_section_info *questionable = 0; | |
1003 | int i; | |
1004 | char *p; | |
1005 | ||
1006 | /* The ELF symbol info doesn't include path names, so strip the path | |
1007 | (if any) from the psymtab filename. */ | |
1008 | while (0 != (p = strchr (filename, '/'))) | |
1009 | filename = p + 1; | |
1010 | ||
1011 | /* FIXME: This linear search could speed up significantly | |
1012 | if it was chained in the right order to match how we search it, | |
1013 | and if we unchained when we found a match. */ | |
1014 | for (; maybe; maybe = maybe->next) | |
1015 | { | |
1016 | if (filename[0] == maybe->filename[0] | |
1017 | && strcmp (filename, maybe->filename) == 0) | |
1018 | { | |
1019 | /* We found a match. But there might be several source files | |
1020 | (from different directories) with the same name. */ | |
1021 | if (0 == maybe->found) | |
1022 | break; | |
1023 | questionable = maybe; /* Might use it later. */ | |
1024 | } | |
1025 | } | |
1026 | ||
1027 | if (maybe == 0 && questionable != 0) | |
1028 | { | |
1029 | complaint (&symfile_complaints, | |
1030 | _("elf/stab section information questionable for %s"), | |
1031 | filename); | |
1032 | maybe = questionable; | |
1033 | } | |
1034 | ||
1035 | if (maybe) | |
1036 | { | |
1037 | /* Found it! Allocate a new psymtab struct, and fill it in. */ | |
1038 | maybe->found++; | |
1039 | pst->section_offsets = (struct section_offsets *) | |
1040 | obstack_alloc (&objfile->objfile_obstack, | |
1041 | SIZEOF_N_SECTION_OFFSETS (objfile->num_sections)); | |
1042 | for (i = 0; i < maybe->num_sections; i++) | |
1043 | (pst->section_offsets)->offsets[i] = maybe->sections[i]; | |
1044 | return; | |
1045 | } | |
1046 | ||
1047 | /* We were unable to find any offsets for this file. Complain. */ | |
1048 | if (dbx->stab_section_info) /* If there *is* any info, */ | |
1049 | complaint (&symfile_complaints, | |
1050 | _("elf/stab section information missing for %s"), filename); | |
1051 | } | |
1052 | \f | |
1053 | /* Register that we are able to handle ELF object file formats. */ | |
1054 | ||
1055 | static const struct sym_fns elf_sym_fns = | |
1056 | { | |
1057 | bfd_target_elf_flavour, | |
1058 | elf_new_init, /* init anything gbl to entire symtab */ | |
1059 | elf_symfile_init, /* read initial info, setup for sym_read() */ | |
1060 | elf_symfile_read, /* read a symbol file into symtab */ | |
1061 | elf_symfile_finish, /* finished with file, cleanup */ | |
1062 | default_symfile_offsets, /* Translate ext. to int. relocation */ | |
1063 | elf_symfile_segments, /* Get segment information from a file. */ | |
1064 | NULL, | |
1065 | default_symfile_relocate, /* Relocate a debug section. */ | |
1066 | &psym_functions | |
1067 | }; | |
1068 | ||
1069 | /* The same as elf_sym_fns, but not registered and uses the | |
1070 | DWARF-specific GNU index rather than psymtab. */ | |
1071 | static const struct sym_fns elf_sym_fns_gdb_index = | |
1072 | { | |
1073 | bfd_target_elf_flavour, | |
1074 | elf_new_init, /* init anything gbl to entire symab */ | |
1075 | elf_symfile_init, /* read initial info, setup for sym_red() */ | |
1076 | elf_symfile_read, /* read a symbol file into symtab */ | |
1077 | elf_symfile_finish, /* finished with file, cleanup */ | |
1078 | default_symfile_offsets, /* Translate ext. to int. relocatin */ | |
1079 | elf_symfile_segments, /* Get segment information from a file. */ | |
1080 | NULL, | |
1081 | default_symfile_relocate, /* Relocate a debug section. */ | |
1082 | &dwarf2_gdb_index_functions | |
1083 | }; | |
1084 | ||
1085 | void | |
1086 | _initialize_elfread (void) | |
1087 | { | |
1088 | add_symtab_fns (&elf_sym_fns); | |
1089 | } |