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1 | /* Read ELF (Executable and Linking Format) object files for GDB. | |
2 | ||
3 | Copyright (C) 1991-2015 Free Software Foundation, Inc. | |
4 | ||
5 | Written by Fred Fish at Cygnus Support. | |
6 | ||
7 | This file is part of GDB. | |
8 | ||
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 3 of the License, or | |
12 | (at your option) any later version. | |
13 | ||
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. | |
18 | ||
19 | You should have received a copy of the GNU General Public License | |
20 | along with this program. If not, see <http://www.gnu.org/licenses/>. */ | |
21 | ||
22 | #include "defs.h" | |
23 | #include "bfd.h" | |
24 | #include "elf-bfd.h" | |
25 | #include "elf/common.h" | |
26 | #include "elf/internal.h" | |
27 | #include "elf/mips.h" | |
28 | #include "symtab.h" | |
29 | #include "symfile.h" | |
30 | #include "objfiles.h" | |
31 | #include "buildsym.h" | |
32 | #include "stabsread.h" | |
33 | #include "gdb-stabs.h" | |
34 | #include "complaints.h" | |
35 | #include "demangle.h" | |
36 | #include "psympriv.h" | |
37 | #include "filenames.h" | |
38 | #include "probe.h" | |
39 | #include "arch-utils.h" | |
40 | #include "gdbtypes.h" | |
41 | #include "value.h" | |
42 | #include "infcall.h" | |
43 | #include "gdbthread.h" | |
44 | #include "regcache.h" | |
45 | #include "bcache.h" | |
46 | #include "gdb_bfd.h" | |
47 | #include "build-id.h" | |
48 | #include "location.h" | |
49 | ||
50 | extern void _initialize_elfread (void); | |
51 | ||
52 | /* Forward declarations. */ | |
53 | extern const struct sym_fns elf_sym_fns_gdb_index; | |
54 | extern const struct sym_fns elf_sym_fns_lazy_psyms; | |
55 | ||
56 | /* The struct elfinfo is available only during ELF symbol table and | |
57 | psymtab reading. It is destroyed at the completion of psymtab-reading. | |
58 | It's local to elf_symfile_read. */ | |
59 | ||
60 | struct elfinfo | |
61 | { | |
62 | asection *stabsect; /* Section pointer for .stab section */ | |
63 | asection *mdebugsect; /* Section pointer for .mdebug section */ | |
64 | }; | |
65 | ||
66 | /* Per-BFD data for probe info. */ | |
67 | ||
68 | static const struct bfd_data *probe_key = NULL; | |
69 | ||
70 | /* Minimal symbols located at the GOT entries for .plt - that is the real | |
71 | pointer where the given entry will jump to. It gets updated by the real | |
72 | function address during lazy ld.so resolving in the inferior. These | |
73 | minimal symbols are indexed for <tab>-completion. */ | |
74 | ||
75 | #define SYMBOL_GOT_PLT_SUFFIX "@got.plt" | |
76 | ||
77 | /* Locate the segments in ABFD. */ | |
78 | ||
79 | static struct symfile_segment_data * | |
80 | elf_symfile_segments (bfd *abfd) | |
81 | { | |
82 | Elf_Internal_Phdr *phdrs, **segments; | |
83 | long phdrs_size; | |
84 | int num_phdrs, num_segments, num_sections, i; | |
85 | asection *sect; | |
86 | struct symfile_segment_data *data; | |
87 | ||
88 | phdrs_size = bfd_get_elf_phdr_upper_bound (abfd); | |
89 | if (phdrs_size == -1) | |
90 | return NULL; | |
91 | ||
92 | phdrs = alloca (phdrs_size); | |
93 | num_phdrs = bfd_get_elf_phdrs (abfd, phdrs); | |
94 | if (num_phdrs == -1) | |
95 | return NULL; | |
96 | ||
97 | num_segments = 0; | |
98 | segments = alloca (sizeof (Elf_Internal_Phdr *) * num_phdrs); | |
99 | for (i = 0; i < num_phdrs; i++) | |
100 | if (phdrs[i].p_type == PT_LOAD) | |
101 | segments[num_segments++] = &phdrs[i]; | |
102 | ||
103 | if (num_segments == 0) | |
104 | return NULL; | |
105 | ||
106 | data = XCNEW (struct symfile_segment_data); | |
107 | data->num_segments = num_segments; | |
108 | data->segment_bases = XCNEWVEC (CORE_ADDR, num_segments); | |
109 | data->segment_sizes = XCNEWVEC (CORE_ADDR, num_segments); | |
110 | ||
111 | for (i = 0; i < num_segments; i++) | |
112 | { | |
113 | data->segment_bases[i] = segments[i]->p_vaddr; | |
114 | data->segment_sizes[i] = segments[i]->p_memsz; | |
115 | } | |
116 | ||
117 | num_sections = bfd_count_sections (abfd); | |
118 | data->segment_info = XCNEWVEC (int, num_sections); | |
119 | ||
120 | for (i = 0, sect = abfd->sections; sect != NULL; i++, sect = sect->next) | |
121 | { | |
122 | int j; | |
123 | CORE_ADDR vma; | |
124 | ||
125 | if ((bfd_get_section_flags (abfd, sect) & SEC_ALLOC) == 0) | |
126 | continue; | |
127 | ||
128 | vma = bfd_get_section_vma (abfd, sect); | |
129 | ||
130 | for (j = 0; j < num_segments; j++) | |
131 | if (segments[j]->p_memsz > 0 | |
132 | && vma >= segments[j]->p_vaddr | |
133 | && (vma - segments[j]->p_vaddr) < segments[j]->p_memsz) | |
134 | { | |
135 | data->segment_info[i] = j + 1; | |
136 | break; | |
137 | } | |
138 | ||
139 | /* We should have found a segment for every non-empty section. | |
140 | If we haven't, we will not relocate this section by any | |
141 | offsets we apply to the segments. As an exception, do not | |
142 | warn about SHT_NOBITS sections; in normal ELF execution | |
143 | environments, SHT_NOBITS means zero-initialized and belongs | |
144 | in a segment, but in no-OS environments some tools (e.g. ARM | |
145 | RealView) use SHT_NOBITS for uninitialized data. Since it is | |
146 | uninitialized, it doesn't need a program header. Such | |
147 | binaries are not relocatable. */ | |
148 | if (bfd_get_section_size (sect) > 0 && j == num_segments | |
149 | && (bfd_get_section_flags (abfd, sect) & SEC_LOAD) != 0) | |
150 | warning (_("Loadable section \"%s\" outside of ELF segments"), | |
151 | bfd_section_name (abfd, sect)); | |
152 | } | |
153 | ||
154 | return data; | |
155 | } | |
156 | ||
157 | /* We are called once per section from elf_symfile_read. We | |
158 | need to examine each section we are passed, check to see | |
159 | if it is something we are interested in processing, and | |
160 | if so, stash away some access information for the section. | |
161 | ||
162 | For now we recognize the dwarf debug information sections and | |
163 | line number sections from matching their section names. The | |
164 | ELF definition is no real help here since it has no direct | |
165 | knowledge of DWARF (by design, so any debugging format can be | |
166 | used). | |
167 | ||
168 | We also recognize the ".stab" sections used by the Sun compilers | |
169 | released with Solaris 2. | |
170 | ||
171 | FIXME: The section names should not be hardwired strings (what | |
172 | should they be? I don't think most object file formats have enough | |
173 | section flags to specify what kind of debug section it is. | |
174 | -kingdon). */ | |
175 | ||
176 | static void | |
177 | elf_locate_sections (bfd *ignore_abfd, asection *sectp, void *eip) | |
178 | { | |
179 | struct elfinfo *ei; | |
180 | ||
181 | ei = (struct elfinfo *) eip; | |
182 | if (strcmp (sectp->name, ".stab") == 0) | |
183 | { | |
184 | ei->stabsect = sectp; | |
185 | } | |
186 | else if (strcmp (sectp->name, ".mdebug") == 0) | |
187 | { | |
188 | ei->mdebugsect = sectp; | |
189 | } | |
190 | } | |
191 | ||
192 | static struct minimal_symbol * | |
193 | record_minimal_symbol (const char *name, int name_len, int copy_name, | |
194 | CORE_ADDR address, | |
195 | enum minimal_symbol_type ms_type, | |
196 | asection *bfd_section, struct objfile *objfile) | |
197 | { | |
198 | struct gdbarch *gdbarch = get_objfile_arch (objfile); | |
199 | ||
200 | if (ms_type == mst_text || ms_type == mst_file_text | |
201 | || ms_type == mst_text_gnu_ifunc) | |
202 | address = gdbarch_addr_bits_remove (gdbarch, address); | |
203 | ||
204 | return prim_record_minimal_symbol_full (name, name_len, copy_name, address, | |
205 | ms_type, | |
206 | gdb_bfd_section_index (objfile->obfd, | |
207 | bfd_section), | |
208 | objfile); | |
209 | } | |
210 | ||
211 | /* Read the symbol table of an ELF file. | |
212 | ||
213 | Given an objfile, a symbol table, and a flag indicating whether the | |
214 | symbol table contains regular, dynamic, or synthetic symbols, add all | |
215 | the global function and data symbols to the minimal symbol table. | |
216 | ||
217 | In stabs-in-ELF, as implemented by Sun, there are some local symbols | |
218 | defined in the ELF symbol table, which can be used to locate | |
219 | the beginnings of sections from each ".o" file that was linked to | |
220 | form the executable objfile. We gather any such info and record it | |
221 | in data structures hung off the objfile's private data. */ | |
222 | ||
223 | #define ST_REGULAR 0 | |
224 | #define ST_DYNAMIC 1 | |
225 | #define ST_SYNTHETIC 2 | |
226 | ||
227 | static void | |
228 | elf_symtab_read (struct objfile *objfile, int type, | |
229 | long number_of_symbols, asymbol **symbol_table, | |
230 | int copy_names) | |
231 | { | |
232 | struct gdbarch *gdbarch = get_objfile_arch (objfile); | |
233 | asymbol *sym; | |
234 | long i; | |
235 | CORE_ADDR symaddr; | |
236 | CORE_ADDR offset; | |
237 | enum minimal_symbol_type ms_type; | |
238 | /* Name of the last file symbol. This is either a constant string or is | |
239 | saved on the objfile's filename cache. */ | |
240 | const char *filesymname = ""; | |
241 | struct dbx_symfile_info *dbx = DBX_SYMFILE_INFO (objfile); | |
242 | int stripped = (bfd_get_symcount (objfile->obfd) == 0); | |
243 | int elf_make_msymbol_special_p | |
244 | = gdbarch_elf_make_msymbol_special_p (gdbarch); | |
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, | |
267 | gdb_bfd_section_index (objfile->obfd, sym->section)); | |
268 | if (type == ST_DYNAMIC | |
269 | && sym->section == bfd_und_section_ptr | |
270 | && (sym->flags & BSF_FUNCTION)) | |
271 | { | |
272 | struct minimal_symbol *msym; | |
273 | bfd *abfd = objfile->obfd; | |
274 | asection *sect; | |
275 | ||
276 | /* Symbol is a reference to a function defined in | |
277 | a shared library. | |
278 | If its value is non zero then it is usually the address | |
279 | of the corresponding entry in the procedure linkage table, | |
280 | plus the desired section offset. | |
281 | If its value is zero then the dynamic linker has to resolve | |
282 | the symbol. We are unable to find any meaningful address | |
283 | for this symbol in the executable file, so we skip it. */ | |
284 | symaddr = sym->value; | |
285 | if (symaddr == 0) | |
286 | continue; | |
287 | ||
288 | /* sym->section is the undefined section. However, we want to | |
289 | record the section where the PLT stub resides with the | |
290 | minimal symbol. Search the section table for the one that | |
291 | covers the stub's address. */ | |
292 | for (sect = abfd->sections; sect != NULL; sect = sect->next) | |
293 | { | |
294 | if ((bfd_get_section_flags (abfd, sect) & SEC_ALLOC) == 0) | |
295 | continue; | |
296 | ||
297 | if (symaddr >= bfd_get_section_vma (abfd, sect) | |
298 | && symaddr < bfd_get_section_vma (abfd, sect) | |
299 | + bfd_get_section_size (sect)) | |
300 | break; | |
301 | } | |
302 | if (!sect) | |
303 | continue; | |
304 | ||
305 | /* On ia64-hpux, we have discovered that the system linker | |
306 | adds undefined symbols with nonzero addresses that cannot | |
307 | be right (their address points inside the code of another | |
308 | function in the .text section). This creates problems | |
309 | when trying to determine which symbol corresponds to | |
310 | a given address. | |
311 | ||
312 | We try to detect those buggy symbols by checking which | |
313 | section we think they correspond to. Normally, PLT symbols | |
314 | are stored inside their own section, and the typical name | |
315 | for that section is ".plt". So, if there is a ".plt" | |
316 | section, and yet the section name of our symbol does not | |
317 | start with ".plt", we ignore that symbol. */ | |
318 | if (!startswith (sect->name, ".plt") | |
319 | && bfd_get_section_by_name (abfd, ".plt") != NULL) | |
320 | continue; | |
321 | ||
322 | msym = record_minimal_symbol | |
323 | (sym->name, strlen (sym->name), copy_names, | |
324 | symaddr, mst_solib_trampoline, sect, objfile); | |
325 | if (msym != NULL) | |
326 | { | |
327 | msym->filename = filesymname; | |
328 | if (elf_make_msymbol_special_p) | |
329 | gdbarch_elf_make_msymbol_special (gdbarch, sym, msym); | |
330 | } | |
331 | continue; | |
332 | } | |
333 | ||
334 | /* If it is a nonstripped executable, do not enter dynamic | |
335 | symbols, as the dynamic symbol table is usually a subset | |
336 | of the main symbol table. */ | |
337 | if (type == ST_DYNAMIC && !stripped) | |
338 | continue; | |
339 | if (sym->flags & BSF_FILE) | |
340 | { | |
341 | filesymname = bcache (sym->name, strlen (sym->name) + 1, | |
342 | objfile->per_bfd->filename_cache); | |
343 | } | |
344 | else if (sym->flags & BSF_SECTION_SYM) | |
345 | continue; | |
346 | else if (sym->flags & (BSF_GLOBAL | BSF_LOCAL | BSF_WEAK | |
347 | | BSF_GNU_UNIQUE)) | |
348 | { | |
349 | struct minimal_symbol *msym; | |
350 | ||
351 | /* Select global/local/weak symbols. Note that bfd puts abs | |
352 | symbols in their own section, so all symbols we are | |
353 | interested in will have a section. */ | |
354 | /* Bfd symbols are section relative. */ | |
355 | symaddr = sym->value + sym->section->vma; | |
356 | /* For non-absolute symbols, use the type of the section | |
357 | they are relative to, to intuit text/data. Bfd provides | |
358 | no way of figuring this out for absolute symbols. */ | |
359 | if (sym->section == bfd_abs_section_ptr) | |
360 | { | |
361 | /* This is a hack to get the minimal symbol type | |
362 | right for Irix 5, which has absolute addresses | |
363 | with special section indices for dynamic symbols. | |
364 | ||
365 | NOTE: uweigand-20071112: Synthetic symbols do not | |
366 | have an ELF-private part, so do not touch those. */ | |
367 | unsigned int shndx = type == ST_SYNTHETIC ? 0 : | |
368 | ((elf_symbol_type *) sym)->internal_elf_sym.st_shndx; | |
369 | ||
370 | switch (shndx) | |
371 | { | |
372 | case SHN_MIPS_TEXT: | |
373 | ms_type = mst_text; | |
374 | break; | |
375 | case SHN_MIPS_DATA: | |
376 | ms_type = mst_data; | |
377 | break; | |
378 | case SHN_MIPS_ACOMMON: | |
379 | ms_type = mst_bss; | |
380 | break; | |
381 | default: | |
382 | ms_type = mst_abs; | |
383 | } | |
384 | ||
385 | /* If it is an Irix dynamic symbol, skip section name | |
386 | symbols, relocate all others by section offset. */ | |
387 | if (ms_type != mst_abs) | |
388 | { | |
389 | if (sym->name[0] == '.') | |
390 | continue; | |
391 | } | |
392 | } | |
393 | else if (sym->section->flags & SEC_CODE) | |
394 | { | |
395 | if (sym->flags & (BSF_GLOBAL | BSF_WEAK | BSF_GNU_UNIQUE)) | |
396 | { | |
397 | if (sym->flags & BSF_GNU_INDIRECT_FUNCTION) | |
398 | ms_type = mst_text_gnu_ifunc; | |
399 | else | |
400 | ms_type = mst_text; | |
401 | } | |
402 | /* The BSF_SYNTHETIC check is there to omit ppc64 function | |
403 | descriptors mistaken for static functions starting with 'L'. | |
404 | */ | |
405 | else if ((sym->name[0] == '.' && sym->name[1] == 'L' | |
406 | && (sym->flags & BSF_SYNTHETIC) == 0) | |
407 | || ((sym->flags & BSF_LOCAL) | |
408 | && sym->name[0] == '$' | |
409 | && sym->name[1] == 'L')) | |
410 | /* Looks like a compiler-generated label. Skip | |
411 | it. The assembler should be skipping these (to | |
412 | keep executables small), but apparently with | |
413 | gcc on the (deleted) delta m88k SVR4, it loses. | |
414 | So to have us check too should be harmless (but | |
415 | I encourage people to fix this in the assembler | |
416 | instead of adding checks here). */ | |
417 | continue; | |
418 | else | |
419 | { | |
420 | ms_type = mst_file_text; | |
421 | } | |
422 | } | |
423 | else if (sym->section->flags & SEC_ALLOC) | |
424 | { | |
425 | if (sym->flags & (BSF_GLOBAL | BSF_WEAK | BSF_GNU_UNIQUE)) | |
426 | { | |
427 | if (sym->section->flags & SEC_LOAD) | |
428 | { | |
429 | ms_type = mst_data; | |
430 | } | |
431 | else | |
432 | { | |
433 | ms_type = mst_bss; | |
434 | } | |
435 | } | |
436 | else if (sym->flags & BSF_LOCAL) | |
437 | { | |
438 | if (sym->section->flags & SEC_LOAD) | |
439 | { | |
440 | ms_type = mst_file_data; | |
441 | } | |
442 | else | |
443 | { | |
444 | ms_type = mst_file_bss; | |
445 | } | |
446 | } | |
447 | else | |
448 | { | |
449 | ms_type = mst_unknown; | |
450 | } | |
451 | } | |
452 | else | |
453 | { | |
454 | /* FIXME: Solaris2 shared libraries include lots of | |
455 | odd "absolute" and "undefined" symbols, that play | |
456 | hob with actions like finding what function the PC | |
457 | is in. Ignore them if they aren't text, data, or bss. */ | |
458 | /* ms_type = mst_unknown; */ | |
459 | continue; /* Skip this symbol. */ | |
460 | } | |
461 | msym = record_minimal_symbol | |
462 | (sym->name, strlen (sym->name), copy_names, symaddr, | |
463 | ms_type, sym->section, objfile); | |
464 | ||
465 | if (msym) | |
466 | { | |
467 | /* NOTE: uweigand-20071112: A synthetic symbol does not have an | |
468 | ELF-private part. */ | |
469 | if (type != ST_SYNTHETIC) | |
470 | { | |
471 | /* Pass symbol size field in via BFD. FIXME!!! */ | |
472 | elf_symbol_type *elf_sym = (elf_symbol_type *) sym; | |
473 | SET_MSYMBOL_SIZE (msym, elf_sym->internal_elf_sym.st_size); | |
474 | } | |
475 | ||
476 | msym->filename = filesymname; | |
477 | if (elf_make_msymbol_special_p) | |
478 | gdbarch_elf_make_msymbol_special (gdbarch, sym, msym); | |
479 | } | |
480 | ||
481 | /* If we see a default versioned symbol, install it under | |
482 | its version-less name. */ | |
483 | if (msym != NULL) | |
484 | { | |
485 | const char *atsign = strchr (sym->name, '@'); | |
486 | ||
487 | if (atsign != NULL && atsign[1] == '@' && atsign > sym->name) | |
488 | { | |
489 | int len = atsign - sym->name; | |
490 | ||
491 | record_minimal_symbol (sym->name, len, 1, symaddr, | |
492 | ms_type, sym->section, objfile); | |
493 | } | |
494 | } | |
495 | ||
496 | /* For @plt symbols, also record a trampoline to the | |
497 | destination symbol. The @plt symbol will be used in | |
498 | disassembly, and the trampoline will be used when we are | |
499 | trying to find the target. */ | |
500 | if (msym && ms_type == mst_text && type == ST_SYNTHETIC) | |
501 | { | |
502 | int len = strlen (sym->name); | |
503 | ||
504 | if (len > 4 && strcmp (sym->name + len - 4, "@plt") == 0) | |
505 | { | |
506 | struct minimal_symbol *mtramp; | |
507 | ||
508 | mtramp = record_minimal_symbol (sym->name, len - 4, 1, | |
509 | symaddr, | |
510 | mst_solib_trampoline, | |
511 | sym->section, objfile); | |
512 | if (mtramp) | |
513 | { | |
514 | SET_MSYMBOL_SIZE (mtramp, MSYMBOL_SIZE (msym)); | |
515 | mtramp->created_by_gdb = 1; | |
516 | mtramp->filename = filesymname; | |
517 | if (elf_make_msymbol_special_p) | |
518 | gdbarch_elf_make_msymbol_special (gdbarch, | |
519 | sym, mtramp); | |
520 | } | |
521 | } | |
522 | } | |
523 | } | |
524 | } | |
525 | } | |
526 | ||
527 | /* Build minimal symbols named `function@got.plt' (see SYMBOL_GOT_PLT_SUFFIX) | |
528 | for later look ups of which function to call when user requests | |
529 | a STT_GNU_IFUNC function. As the STT_GNU_IFUNC type is found at the target | |
530 | library defining `function' we cannot yet know while reading OBJFILE which | |
531 | of the SYMBOL_GOT_PLT_SUFFIX entries will be needed and later | |
532 | DYN_SYMBOL_TABLE is no longer easily available for OBJFILE. */ | |
533 | ||
534 | static void | |
535 | elf_rel_plt_read (struct objfile *objfile, asymbol **dyn_symbol_table) | |
536 | { | |
537 | bfd *obfd = objfile->obfd; | |
538 | const struct elf_backend_data *bed = get_elf_backend_data (obfd); | |
539 | asection *plt, *relplt, *got_plt; | |
540 | int plt_elf_idx; | |
541 | bfd_size_type reloc_count, reloc; | |
542 | char *string_buffer = NULL; | |
543 | size_t string_buffer_size = 0; | |
544 | struct cleanup *back_to; | |
545 | struct gdbarch *gdbarch = get_objfile_arch (objfile); | |
546 | struct type *ptr_type = builtin_type (gdbarch)->builtin_data_ptr; | |
547 | size_t ptr_size = TYPE_LENGTH (ptr_type); | |
548 | ||
549 | if (objfile->separate_debug_objfile_backlink) | |
550 | return; | |
551 | ||
552 | plt = bfd_get_section_by_name (obfd, ".plt"); | |
553 | if (plt == NULL) | |
554 | return; | |
555 | plt_elf_idx = elf_section_data (plt)->this_idx; | |
556 | ||
557 | got_plt = bfd_get_section_by_name (obfd, ".got.plt"); | |
558 | if (got_plt == NULL) | |
559 | { | |
560 | /* For platforms where there is no separate .got.plt. */ | |
561 | got_plt = bfd_get_section_by_name (obfd, ".got"); | |
562 | if (got_plt == NULL) | |
563 | return; | |
564 | } | |
565 | ||
566 | /* This search algorithm is from _bfd_elf_canonicalize_dynamic_reloc. */ | |
567 | for (relplt = obfd->sections; relplt != NULL; relplt = relplt->next) | |
568 | if (elf_section_data (relplt)->this_hdr.sh_info == plt_elf_idx | |
569 | && (elf_section_data (relplt)->this_hdr.sh_type == SHT_REL | |
570 | || elf_section_data (relplt)->this_hdr.sh_type == SHT_RELA)) | |
571 | break; | |
572 | if (relplt == NULL) | |
573 | return; | |
574 | ||
575 | if (! bed->s->slurp_reloc_table (obfd, relplt, dyn_symbol_table, TRUE)) | |
576 | return; | |
577 | ||
578 | back_to = make_cleanup (free_current_contents, &string_buffer); | |
579 | ||
580 | reloc_count = relplt->size / elf_section_data (relplt)->this_hdr.sh_entsize; | |
581 | for (reloc = 0; reloc < reloc_count; reloc++) | |
582 | { | |
583 | const char *name; | |
584 | struct minimal_symbol *msym; | |
585 | CORE_ADDR address; | |
586 | const size_t got_suffix_len = strlen (SYMBOL_GOT_PLT_SUFFIX); | |
587 | size_t name_len; | |
588 | ||
589 | name = bfd_asymbol_name (*relplt->relocation[reloc].sym_ptr_ptr); | |
590 | name_len = strlen (name); | |
591 | address = relplt->relocation[reloc].address; | |
592 | ||
593 | /* Does the pointer reside in the .got.plt section? */ | |
594 | if (!(bfd_get_section_vma (obfd, got_plt) <= address | |
595 | && address < bfd_get_section_vma (obfd, got_plt) | |
596 | + bfd_get_section_size (got_plt))) | |
597 | continue; | |
598 | ||
599 | /* We cannot check if NAME is a reference to mst_text_gnu_ifunc as in | |
600 | OBJFILE the symbol is undefined and the objfile having NAME defined | |
601 | may not yet have been loaded. */ | |
602 | ||
603 | if (string_buffer_size < name_len + got_suffix_len + 1) | |
604 | { | |
605 | string_buffer_size = 2 * (name_len + got_suffix_len); | |
606 | string_buffer = xrealloc (string_buffer, string_buffer_size); | |
607 | } | |
608 | memcpy (string_buffer, name, name_len); | |
609 | memcpy (&string_buffer[name_len], SYMBOL_GOT_PLT_SUFFIX, | |
610 | got_suffix_len + 1); | |
611 | ||
612 | msym = record_minimal_symbol (string_buffer, name_len + got_suffix_len, | |
613 | 1, address, mst_slot_got_plt, got_plt, | |
614 | objfile); | |
615 | if (msym) | |
616 | SET_MSYMBOL_SIZE (msym, ptr_size); | |
617 | } | |
618 | ||
619 | do_cleanups (back_to); | |
620 | } | |
621 | ||
622 | /* The data pointer is htab_t for gnu_ifunc_record_cache_unchecked. */ | |
623 | ||
624 | static const struct objfile_data *elf_objfile_gnu_ifunc_cache_data; | |
625 | ||
626 | /* Map function names to CORE_ADDR in elf_objfile_gnu_ifunc_cache_data. */ | |
627 | ||
628 | struct elf_gnu_ifunc_cache | |
629 | { | |
630 | /* This is always a function entry address, not a function descriptor. */ | |
631 | CORE_ADDR addr; | |
632 | ||
633 | char name[1]; | |
634 | }; | |
635 | ||
636 | /* htab_hash for elf_objfile_gnu_ifunc_cache_data. */ | |
637 | ||
638 | static hashval_t | |
639 | elf_gnu_ifunc_cache_hash (const void *a_voidp) | |
640 | { | |
641 | const struct elf_gnu_ifunc_cache *a = a_voidp; | |
642 | ||
643 | return htab_hash_string (a->name); | |
644 | } | |
645 | ||
646 | /* htab_eq for elf_objfile_gnu_ifunc_cache_data. */ | |
647 | ||
648 | static int | |
649 | elf_gnu_ifunc_cache_eq (const void *a_voidp, const void *b_voidp) | |
650 | { | |
651 | const struct elf_gnu_ifunc_cache *a = a_voidp; | |
652 | const struct elf_gnu_ifunc_cache *b = b_voidp; | |
653 | ||
654 | return strcmp (a->name, b->name) == 0; | |
655 | } | |
656 | ||
657 | /* Record the target function address of a STT_GNU_IFUNC function NAME is the | |
658 | function entry address ADDR. Return 1 if NAME and ADDR are considered as | |
659 | valid and therefore they were successfully recorded, return 0 otherwise. | |
660 | ||
661 | Function does not expect a duplicate entry. Use | |
662 | elf_gnu_ifunc_resolve_by_cache first to check if the entry for NAME already | |
663 | exists. */ | |
664 | ||
665 | static int | |
666 | elf_gnu_ifunc_record_cache (const char *name, CORE_ADDR addr) | |
667 | { | |
668 | struct bound_minimal_symbol msym; | |
669 | asection *sect; | |
670 | struct objfile *objfile; | |
671 | htab_t htab; | |
672 | struct elf_gnu_ifunc_cache entry_local, *entry_p; | |
673 | void **slot; | |
674 | ||
675 | msym = lookup_minimal_symbol_by_pc (addr); | |
676 | if (msym.minsym == NULL) | |
677 | return 0; | |
678 | if (BMSYMBOL_VALUE_ADDRESS (msym) != addr) | |
679 | return 0; | |
680 | /* minimal symbols have always SYMBOL_OBJ_SECTION non-NULL. */ | |
681 | sect = MSYMBOL_OBJ_SECTION (msym.objfile, msym.minsym)->the_bfd_section; | |
682 | objfile = msym.objfile; | |
683 | ||
684 | /* If .plt jumps back to .plt the symbol is still deferred for later | |
685 | resolution and it has no use for GDB. Besides ".text" this symbol can | |
686 | reside also in ".opd" for ppc64 function descriptor. */ | |
687 | if (strcmp (bfd_get_section_name (objfile->obfd, sect), ".plt") == 0) | |
688 | return 0; | |
689 | ||
690 | htab = objfile_data (objfile, elf_objfile_gnu_ifunc_cache_data); | |
691 | if (htab == NULL) | |
692 | { | |
693 | htab = htab_create_alloc_ex (1, elf_gnu_ifunc_cache_hash, | |
694 | elf_gnu_ifunc_cache_eq, | |
695 | NULL, &objfile->objfile_obstack, | |
696 | hashtab_obstack_allocate, | |
697 | dummy_obstack_deallocate); | |
698 | set_objfile_data (objfile, elf_objfile_gnu_ifunc_cache_data, htab); | |
699 | } | |
700 | ||
701 | entry_local.addr = addr; | |
702 | obstack_grow (&objfile->objfile_obstack, &entry_local, | |
703 | offsetof (struct elf_gnu_ifunc_cache, name)); | |
704 | obstack_grow_str0 (&objfile->objfile_obstack, name); | |
705 | entry_p = obstack_finish (&objfile->objfile_obstack); | |
706 | ||
707 | slot = htab_find_slot (htab, entry_p, INSERT); | |
708 | if (*slot != NULL) | |
709 | { | |
710 | struct elf_gnu_ifunc_cache *entry_found_p = *slot; | |
711 | struct gdbarch *gdbarch = get_objfile_arch (objfile); | |
712 | ||
713 | if (entry_found_p->addr != addr) | |
714 | { | |
715 | /* This case indicates buggy inferior program, the resolved address | |
716 | should never change. */ | |
717 | ||
718 | warning (_("gnu-indirect-function \"%s\" has changed its resolved " | |
719 | "function_address from %s to %s"), | |
720 | name, paddress (gdbarch, entry_found_p->addr), | |
721 | paddress (gdbarch, addr)); | |
722 | } | |
723 | ||
724 | /* New ENTRY_P is here leaked/duplicate in the OBJFILE obstack. */ | |
725 | } | |
726 | *slot = entry_p; | |
727 | ||
728 | return 1; | |
729 | } | |
730 | ||
731 | /* Try to find the target resolved function entry address of a STT_GNU_IFUNC | |
732 | function NAME. If the address is found it is stored to *ADDR_P (if ADDR_P | |
733 | is not NULL) and the function returns 1. It returns 0 otherwise. | |
734 | ||
735 | Only the elf_objfile_gnu_ifunc_cache_data hash table is searched by this | |
736 | function. */ | |
737 | ||
738 | static int | |
739 | elf_gnu_ifunc_resolve_by_cache (const char *name, CORE_ADDR *addr_p) | |
740 | { | |
741 | struct objfile *objfile; | |
742 | ||
743 | ALL_PSPACE_OBJFILES (current_program_space, objfile) | |
744 | { | |
745 | htab_t htab; | |
746 | struct elf_gnu_ifunc_cache *entry_p; | |
747 | void **slot; | |
748 | ||
749 | htab = objfile_data (objfile, elf_objfile_gnu_ifunc_cache_data); | |
750 | if (htab == NULL) | |
751 | continue; | |
752 | ||
753 | entry_p = alloca (sizeof (*entry_p) + strlen (name)); | |
754 | strcpy (entry_p->name, name); | |
755 | ||
756 | slot = htab_find_slot (htab, entry_p, NO_INSERT); | |
757 | if (slot == NULL) | |
758 | continue; | |
759 | entry_p = *slot; | |
760 | gdb_assert (entry_p != NULL); | |
761 | ||
762 | if (addr_p) | |
763 | *addr_p = entry_p->addr; | |
764 | return 1; | |
765 | } | |
766 | ||
767 | return 0; | |
768 | } | |
769 | ||
770 | /* Try to find the target resolved function entry address of a STT_GNU_IFUNC | |
771 | function NAME. If the address is found it is stored to *ADDR_P (if ADDR_P | |
772 | is not NULL) and the function returns 1. It returns 0 otherwise. | |
773 | ||
774 | Only the SYMBOL_GOT_PLT_SUFFIX locations are searched by this function. | |
775 | elf_gnu_ifunc_resolve_by_cache must have been already called for NAME to | |
776 | prevent cache entries duplicates. */ | |
777 | ||
778 | static int | |
779 | elf_gnu_ifunc_resolve_by_got (const char *name, CORE_ADDR *addr_p) | |
780 | { | |
781 | char *name_got_plt; | |
782 | struct objfile *objfile; | |
783 | const size_t got_suffix_len = strlen (SYMBOL_GOT_PLT_SUFFIX); | |
784 | ||
785 | name_got_plt = alloca (strlen (name) + got_suffix_len + 1); | |
786 | sprintf (name_got_plt, "%s" SYMBOL_GOT_PLT_SUFFIX, name); | |
787 | ||
788 | ALL_PSPACE_OBJFILES (current_program_space, objfile) | |
789 | { | |
790 | bfd *obfd = objfile->obfd; | |
791 | struct gdbarch *gdbarch = get_objfile_arch (objfile); | |
792 | struct type *ptr_type = builtin_type (gdbarch)->builtin_data_ptr; | |
793 | size_t ptr_size = TYPE_LENGTH (ptr_type); | |
794 | CORE_ADDR pointer_address, addr; | |
795 | asection *plt; | |
796 | gdb_byte *buf = alloca (ptr_size); | |
797 | struct bound_minimal_symbol msym; | |
798 | ||
799 | msym = lookup_minimal_symbol (name_got_plt, NULL, objfile); | |
800 | if (msym.minsym == NULL) | |
801 | continue; | |
802 | if (MSYMBOL_TYPE (msym.minsym) != mst_slot_got_plt) | |
803 | continue; | |
804 | pointer_address = BMSYMBOL_VALUE_ADDRESS (msym); | |
805 | ||
806 | plt = bfd_get_section_by_name (obfd, ".plt"); | |
807 | if (plt == NULL) | |
808 | continue; | |
809 | ||
810 | if (MSYMBOL_SIZE (msym.minsym) != ptr_size) | |
811 | continue; | |
812 | if (target_read_memory (pointer_address, buf, ptr_size) != 0) | |
813 | continue; | |
814 | addr = extract_typed_address (buf, ptr_type); | |
815 | addr = gdbarch_convert_from_func_ptr_addr (gdbarch, addr, | |
816 | ¤t_target); | |
817 | addr = gdbarch_addr_bits_remove (gdbarch, addr); | |
818 | ||
819 | if (addr_p) | |
820 | *addr_p = addr; | |
821 | if (elf_gnu_ifunc_record_cache (name, addr)) | |
822 | return 1; | |
823 | } | |
824 | ||
825 | return 0; | |
826 | } | |
827 | ||
828 | /* Try to find the target resolved function entry address of a STT_GNU_IFUNC | |
829 | function NAME. If the address is found it is stored to *ADDR_P (if ADDR_P | |
830 | is not NULL) and the function returns 1. It returns 0 otherwise. | |
831 | ||
832 | Both the elf_objfile_gnu_ifunc_cache_data hash table and | |
833 | SYMBOL_GOT_PLT_SUFFIX locations are searched by this function. */ | |
834 | ||
835 | static int | |
836 | elf_gnu_ifunc_resolve_name (const char *name, CORE_ADDR *addr_p) | |
837 | { | |
838 | if (elf_gnu_ifunc_resolve_by_cache (name, addr_p)) | |
839 | return 1; | |
840 | ||
841 | if (elf_gnu_ifunc_resolve_by_got (name, addr_p)) | |
842 | return 1; | |
843 | ||
844 | return 0; | |
845 | } | |
846 | ||
847 | /* Call STT_GNU_IFUNC - a function returning addresss of a real function to | |
848 | call. PC is theSTT_GNU_IFUNC resolving function entry. The value returned | |
849 | is the entry point of the resolved STT_GNU_IFUNC target function to call. | |
850 | */ | |
851 | ||
852 | static CORE_ADDR | |
853 | elf_gnu_ifunc_resolve_addr (struct gdbarch *gdbarch, CORE_ADDR pc) | |
854 | { | |
855 | const char *name_at_pc; | |
856 | CORE_ADDR start_at_pc, address; | |
857 | struct type *func_func_type = builtin_type (gdbarch)->builtin_func_func; | |
858 | struct value *function, *address_val; | |
859 | ||
860 | /* Try first any non-intrusive methods without an inferior call. */ | |
861 | ||
862 | if (find_pc_partial_function (pc, &name_at_pc, &start_at_pc, NULL) | |
863 | && start_at_pc == pc) | |
864 | { | |
865 | if (elf_gnu_ifunc_resolve_name (name_at_pc, &address)) | |
866 | return address; | |
867 | } | |
868 | else | |
869 | name_at_pc = NULL; | |
870 | ||
871 | function = allocate_value (func_func_type); | |
872 | set_value_address (function, pc); | |
873 | ||
874 | /* STT_GNU_IFUNC resolver functions have no parameters. FUNCTION is the | |
875 | function entry address. ADDRESS may be a function descriptor. */ | |
876 | ||
877 | address_val = call_function_by_hand (function, 0, NULL); | |
878 | address = value_as_address (address_val); | |
879 | address = gdbarch_convert_from_func_ptr_addr (gdbarch, address, | |
880 | ¤t_target); | |
881 | address = gdbarch_addr_bits_remove (gdbarch, address); | |
882 | ||
883 | if (name_at_pc) | |
884 | elf_gnu_ifunc_record_cache (name_at_pc, address); | |
885 | ||
886 | return address; | |
887 | } | |
888 | ||
889 | /* Handle inferior hit of bp_gnu_ifunc_resolver, see its definition. */ | |
890 | ||
891 | static void | |
892 | elf_gnu_ifunc_resolver_stop (struct breakpoint *b) | |
893 | { | |
894 | struct breakpoint *b_return; | |
895 | struct frame_info *prev_frame = get_prev_frame (get_current_frame ()); | |
896 | struct frame_id prev_frame_id = get_stack_frame_id (prev_frame); | |
897 | CORE_ADDR prev_pc = get_frame_pc (prev_frame); | |
898 | int thread_id = pid_to_thread_id (inferior_ptid); | |
899 | ||
900 | gdb_assert (b->type == bp_gnu_ifunc_resolver); | |
901 | ||
902 | for (b_return = b->related_breakpoint; b_return != b; | |
903 | b_return = b_return->related_breakpoint) | |
904 | { | |
905 | gdb_assert (b_return->type == bp_gnu_ifunc_resolver_return); | |
906 | gdb_assert (b_return->loc != NULL && b_return->loc->next == NULL); | |
907 | gdb_assert (frame_id_p (b_return->frame_id)); | |
908 | ||
909 | if (b_return->thread == thread_id | |
910 | && b_return->loc->requested_address == prev_pc | |
911 | && frame_id_eq (b_return->frame_id, prev_frame_id)) | |
912 | break; | |
913 | } | |
914 | ||
915 | if (b_return == b) | |
916 | { | |
917 | struct symtab_and_line sal; | |
918 | ||
919 | /* No need to call find_pc_line for symbols resolving as this is only | |
920 | a helper breakpointer never shown to the user. */ | |
921 | ||
922 | init_sal (&sal); | |
923 | sal.pspace = current_inferior ()->pspace; | |
924 | sal.pc = prev_pc; | |
925 | sal.section = find_pc_overlay (sal.pc); | |
926 | sal.explicit_pc = 1; | |
927 | b_return = set_momentary_breakpoint (get_frame_arch (prev_frame), sal, | |
928 | prev_frame_id, | |
929 | bp_gnu_ifunc_resolver_return); | |
930 | ||
931 | /* set_momentary_breakpoint invalidates PREV_FRAME. */ | |
932 | prev_frame = NULL; | |
933 | ||
934 | /* Add new b_return to the ring list b->related_breakpoint. */ | |
935 | gdb_assert (b_return->related_breakpoint == b_return); | |
936 | b_return->related_breakpoint = b->related_breakpoint; | |
937 | b->related_breakpoint = b_return; | |
938 | } | |
939 | } | |
940 | ||
941 | /* Handle inferior hit of bp_gnu_ifunc_resolver_return, see its definition. */ | |
942 | ||
943 | static void | |
944 | elf_gnu_ifunc_resolver_return_stop (struct breakpoint *b) | |
945 | { | |
946 | struct gdbarch *gdbarch = get_frame_arch (get_current_frame ()); | |
947 | struct type *func_func_type = builtin_type (gdbarch)->builtin_func_func; | |
948 | struct type *value_type = TYPE_TARGET_TYPE (func_func_type); | |
949 | struct regcache *regcache = get_thread_regcache (inferior_ptid); | |
950 | struct value *func_func; | |
951 | struct value *value; | |
952 | CORE_ADDR resolved_address, resolved_pc; | |
953 | struct symtab_and_line sal; | |
954 | struct symtabs_and_lines sals, sals_end; | |
955 | ||
956 | gdb_assert (b->type == bp_gnu_ifunc_resolver_return); | |
957 | ||
958 | while (b->related_breakpoint != b) | |
959 | { | |
960 | struct breakpoint *b_next = b->related_breakpoint; | |
961 | ||
962 | switch (b->type) | |
963 | { | |
964 | case bp_gnu_ifunc_resolver: | |
965 | break; | |
966 | case bp_gnu_ifunc_resolver_return: | |
967 | delete_breakpoint (b); | |
968 | break; | |
969 | default: | |
970 | internal_error (__FILE__, __LINE__, | |
971 | _("handle_inferior_event: Invalid " | |
972 | "gnu-indirect-function breakpoint type %d"), | |
973 | (int) b->type); | |
974 | } | |
975 | b = b_next; | |
976 | } | |
977 | gdb_assert (b->type == bp_gnu_ifunc_resolver); | |
978 | gdb_assert (b->loc->next == NULL); | |
979 | ||
980 | func_func = allocate_value (func_func_type); | |
981 | set_value_address (func_func, b->loc->related_address); | |
982 | ||
983 | value = allocate_value (value_type); | |
984 | gdbarch_return_value (gdbarch, func_func, value_type, regcache, | |
985 | value_contents_raw (value), NULL); | |
986 | resolved_address = value_as_address (value); | |
987 | resolved_pc = gdbarch_convert_from_func_ptr_addr (gdbarch, | |
988 | resolved_address, | |
989 | ¤t_target); | |
990 | resolved_pc = gdbarch_addr_bits_remove (gdbarch, resolved_pc); | |
991 | ||
992 | gdb_assert (current_program_space == b->pspace || b->pspace == NULL); | |
993 | elf_gnu_ifunc_record_cache (event_location_to_string (b->location), | |
994 | resolved_pc); | |
995 | ||
996 | sal = find_pc_line (resolved_pc, 0); | |
997 | sals.nelts = 1; | |
998 | sals.sals = &sal; | |
999 | sals_end.nelts = 0; | |
1000 | ||
1001 | b->type = bp_breakpoint; | |
1002 | update_breakpoint_locations (b, sals, sals_end); | |
1003 | } | |
1004 | ||
1005 | /* A helper function for elf_symfile_read that reads the minimal | |
1006 | symbols. */ | |
1007 | ||
1008 | static void | |
1009 | elf_read_minimal_symbols (struct objfile *objfile, int symfile_flags, | |
1010 | const struct elfinfo *ei) | |
1011 | { | |
1012 | bfd *synth_abfd, *abfd = objfile->obfd; | |
1013 | struct cleanup *back_to; | |
1014 | long symcount = 0, dynsymcount = 0, synthcount, storage_needed; | |
1015 | asymbol **symbol_table = NULL, **dyn_symbol_table = NULL; | |
1016 | asymbol *synthsyms; | |
1017 | struct dbx_symfile_info *dbx; | |
1018 | ||
1019 | if (symtab_create_debug) | |
1020 | { | |
1021 | fprintf_unfiltered (gdb_stdlog, | |
1022 | "Reading minimal symbols of objfile %s ...\n", | |
1023 | objfile_name (objfile)); | |
1024 | } | |
1025 | ||
1026 | /* If we already have minsyms, then we can skip some work here. | |
1027 | However, if there were stabs or mdebug sections, we go ahead and | |
1028 | redo all the work anyway, because the psym readers for those | |
1029 | kinds of debuginfo need extra information found here. This can | |
1030 | go away once all types of symbols are in the per-BFD object. */ | |
1031 | if (objfile->per_bfd->minsyms_read | |
1032 | && ei->stabsect == NULL | |
1033 | && ei->mdebugsect == NULL) | |
1034 | { | |
1035 | if (symtab_create_debug) | |
1036 | fprintf_unfiltered (gdb_stdlog, | |
1037 | "... minimal symbols previously read\n"); | |
1038 | return; | |
1039 | } | |
1040 | ||
1041 | init_minimal_symbol_collection (); | |
1042 | back_to = make_cleanup_discard_minimal_symbols (); | |
1043 | ||
1044 | /* Allocate struct to keep track of the symfile. */ | |
1045 | dbx = XCNEW (struct dbx_symfile_info); | |
1046 | set_objfile_data (objfile, dbx_objfile_data_key, dbx); | |
1047 | ||
1048 | /* Process the normal ELF symbol table first. */ | |
1049 | ||
1050 | storage_needed = bfd_get_symtab_upper_bound (objfile->obfd); | |
1051 | if (storage_needed < 0) | |
1052 | error (_("Can't read symbols from %s: %s"), | |
1053 | bfd_get_filename (objfile->obfd), | |
1054 | bfd_errmsg (bfd_get_error ())); | |
1055 | ||
1056 | if (storage_needed > 0) | |
1057 | { | |
1058 | /* Memory gets permanently referenced from ABFD after | |
1059 | bfd_canonicalize_symtab so it must not get freed before ABFD gets. */ | |
1060 | ||
1061 | symbol_table = bfd_alloc (abfd, storage_needed); | |
1062 | symcount = bfd_canonicalize_symtab (objfile->obfd, symbol_table); | |
1063 | ||
1064 | if (symcount < 0) | |
1065 | error (_("Can't read symbols from %s: %s"), | |
1066 | bfd_get_filename (objfile->obfd), | |
1067 | bfd_errmsg (bfd_get_error ())); | |
1068 | ||
1069 | elf_symtab_read (objfile, ST_REGULAR, symcount, symbol_table, 0); | |
1070 | } | |
1071 | ||
1072 | /* Add the dynamic symbols. */ | |
1073 | ||
1074 | storage_needed = bfd_get_dynamic_symtab_upper_bound (objfile->obfd); | |
1075 | ||
1076 | if (storage_needed > 0) | |
1077 | { | |
1078 | /* Memory gets permanently referenced from ABFD after | |
1079 | bfd_get_synthetic_symtab so it must not get freed before ABFD gets. | |
1080 | It happens only in the case when elf_slurp_reloc_table sees | |
1081 | asection->relocation NULL. Determining which section is asection is | |
1082 | done by _bfd_elf_get_synthetic_symtab which is all a bfd | |
1083 | implementation detail, though. */ | |
1084 | ||
1085 | dyn_symbol_table = bfd_alloc (abfd, storage_needed); | |
1086 | dynsymcount = bfd_canonicalize_dynamic_symtab (objfile->obfd, | |
1087 | dyn_symbol_table); | |
1088 | ||
1089 | if (dynsymcount < 0) | |
1090 | error (_("Can't read symbols from %s: %s"), | |
1091 | bfd_get_filename (objfile->obfd), | |
1092 | bfd_errmsg (bfd_get_error ())); | |
1093 | ||
1094 | elf_symtab_read (objfile, ST_DYNAMIC, dynsymcount, dyn_symbol_table, 0); | |
1095 | ||
1096 | elf_rel_plt_read (objfile, dyn_symbol_table); | |
1097 | } | |
1098 | ||
1099 | /* Contrary to binutils --strip-debug/--only-keep-debug the strip command from | |
1100 | elfutils (eu-strip) moves even the .symtab section into the .debug file. | |
1101 | ||
1102 | bfd_get_synthetic_symtab on ppc64 for each function descriptor ELF symbol | |
1103 | 'name' creates a new BSF_SYNTHETIC ELF symbol '.name' with its code | |
1104 | address. But with eu-strip files bfd_get_synthetic_symtab would fail to | |
1105 | read the code address from .opd while it reads the .symtab section from | |
1106 | a separate debug info file as the .opd section is SHT_NOBITS there. | |
1107 | ||
1108 | With SYNTH_ABFD the .opd section will be read from the original | |
1109 | backlinked binary where it is valid. */ | |
1110 | ||
1111 | if (objfile->separate_debug_objfile_backlink) | |
1112 | synth_abfd = objfile->separate_debug_objfile_backlink->obfd; | |
1113 | else | |
1114 | synth_abfd = abfd; | |
1115 | ||
1116 | /* Add synthetic symbols - for instance, names for any PLT entries. */ | |
1117 | ||
1118 | synthcount = bfd_get_synthetic_symtab (synth_abfd, symcount, symbol_table, | |
1119 | dynsymcount, dyn_symbol_table, | |
1120 | &synthsyms); | |
1121 | if (synthcount > 0) | |
1122 | { | |
1123 | asymbol **synth_symbol_table; | |
1124 | long i; | |
1125 | ||
1126 | make_cleanup (xfree, synthsyms); | |
1127 | synth_symbol_table = xmalloc (sizeof (asymbol *) * synthcount); | |
1128 | for (i = 0; i < synthcount; i++) | |
1129 | synth_symbol_table[i] = synthsyms + i; | |
1130 | make_cleanup (xfree, synth_symbol_table); | |
1131 | elf_symtab_read (objfile, ST_SYNTHETIC, synthcount, | |
1132 | synth_symbol_table, 1); | |
1133 | } | |
1134 | ||
1135 | /* Install any minimal symbols that have been collected as the current | |
1136 | minimal symbols for this objfile. The debug readers below this point | |
1137 | should not generate new minimal symbols; if they do it's their | |
1138 | responsibility to install them. "mdebug" appears to be the only one | |
1139 | which will do this. */ | |
1140 | ||
1141 | install_minimal_symbols (objfile); | |
1142 | do_cleanups (back_to); | |
1143 | ||
1144 | if (symtab_create_debug) | |
1145 | fprintf_unfiltered (gdb_stdlog, "Done reading minimal symbols.\n"); | |
1146 | } | |
1147 | ||
1148 | /* Scan and build partial symbols for a symbol file. | |
1149 | We have been initialized by a call to elf_symfile_init, which | |
1150 | currently does nothing. | |
1151 | ||
1152 | This function only does the minimum work necessary for letting the | |
1153 | user "name" things symbolically; it does not read the entire symtab. | |
1154 | Instead, it reads the external and static symbols and puts them in partial | |
1155 | symbol tables. When more extensive information is requested of a | |
1156 | file, the corresponding partial symbol table is mutated into a full | |
1157 | fledged symbol table by going back and reading the symbols | |
1158 | for real. | |
1159 | ||
1160 | We look for sections with specific names, to tell us what debug | |
1161 | format to look for: FIXME!!! | |
1162 | ||
1163 | elfstab_build_psymtabs() handles STABS symbols; | |
1164 | mdebug_build_psymtabs() handles ECOFF debugging information. | |
1165 | ||
1166 | Note that ELF files have a "minimal" symbol table, which looks a lot | |
1167 | like a COFF symbol table, but has only the minimal information necessary | |
1168 | for linking. We process this also, and use the information to | |
1169 | build gdb's minimal symbol table. This gives us some minimal debugging | |
1170 | capability even for files compiled without -g. */ | |
1171 | ||
1172 | static void | |
1173 | elf_symfile_read (struct objfile *objfile, int symfile_flags) | |
1174 | { | |
1175 | bfd *abfd = objfile->obfd; | |
1176 | struct elfinfo ei; | |
1177 | ||
1178 | memset ((char *) &ei, 0, sizeof (ei)); | |
1179 | bfd_map_over_sections (abfd, elf_locate_sections, (void *) & ei); | |
1180 | ||
1181 | elf_read_minimal_symbols (objfile, symfile_flags, &ei); | |
1182 | ||
1183 | /* ELF debugging information is inserted into the psymtab in the | |
1184 | order of least informative first - most informative last. Since | |
1185 | the psymtab table is searched `most recent insertion first' this | |
1186 | increases the probability that more detailed debug information | |
1187 | for a section is found. | |
1188 | ||
1189 | For instance, an object file might contain both .mdebug (XCOFF) | |
1190 | and .debug_info (DWARF2) sections then .mdebug is inserted first | |
1191 | (searched last) and DWARF2 is inserted last (searched first). If | |
1192 | we don't do this then the XCOFF info is found first - for code in | |
1193 | an included file XCOFF info is useless. */ | |
1194 | ||
1195 | if (ei.mdebugsect) | |
1196 | { | |
1197 | const struct ecoff_debug_swap *swap; | |
1198 | ||
1199 | /* .mdebug section, presumably holding ECOFF debugging | |
1200 | information. */ | |
1201 | swap = get_elf_backend_data (abfd)->elf_backend_ecoff_debug_swap; | |
1202 | if (swap) | |
1203 | elfmdebug_build_psymtabs (objfile, swap, ei.mdebugsect); | |
1204 | } | |
1205 | if (ei.stabsect) | |
1206 | { | |
1207 | asection *str_sect; | |
1208 | ||
1209 | /* Stab sections have an associated string table that looks like | |
1210 | a separate section. */ | |
1211 | str_sect = bfd_get_section_by_name (abfd, ".stabstr"); | |
1212 | ||
1213 | /* FIXME should probably warn about a stab section without a stabstr. */ | |
1214 | if (str_sect) | |
1215 | elfstab_build_psymtabs (objfile, | |
1216 | ei.stabsect, | |
1217 | str_sect->filepos, | |
1218 | bfd_section_size (abfd, str_sect)); | |
1219 | } | |
1220 | ||
1221 | if (dwarf2_has_info (objfile, NULL)) | |
1222 | { | |
1223 | /* elf_sym_fns_gdb_index cannot handle simultaneous non-DWARF debug | |
1224 | information present in OBJFILE. If there is such debug info present | |
1225 | never use .gdb_index. */ | |
1226 | ||
1227 | if (!objfile_has_partial_symbols (objfile) | |
1228 | && dwarf2_initialize_objfile (objfile)) | |
1229 | objfile_set_sym_fns (objfile, &elf_sym_fns_gdb_index); | |
1230 | else | |
1231 | { | |
1232 | /* It is ok to do this even if the stabs reader made some | |
1233 | partial symbols, because OBJF_PSYMTABS_READ has not been | |
1234 | set, and so our lazy reader function will still be called | |
1235 | when needed. */ | |
1236 | objfile_set_sym_fns (objfile, &elf_sym_fns_lazy_psyms); | |
1237 | } | |
1238 | } | |
1239 | /* If the file has its own symbol tables it has no separate debug | |
1240 | info. `.dynsym'/`.symtab' go to MSYMBOLS, `.debug_info' goes to | |
1241 | SYMTABS/PSYMTABS. `.gnu_debuglink' may no longer be present with | |
1242 | `.note.gnu.build-id'. | |
1243 | ||
1244 | .gnu_debugdata is !objfile_has_partial_symbols because it contains only | |
1245 | .symtab, not .debug_* section. But if we already added .gnu_debugdata as | |
1246 | an objfile via find_separate_debug_file_in_section there was no separate | |
1247 | debug info available. Therefore do not attempt to search for another one, | |
1248 | objfile->separate_debug_objfile->separate_debug_objfile GDB guarantees to | |
1249 | be NULL and we would possibly violate it. */ | |
1250 | ||
1251 | else if (!objfile_has_partial_symbols (objfile) | |
1252 | && objfile->separate_debug_objfile == NULL | |
1253 | && objfile->separate_debug_objfile_backlink == NULL) | |
1254 | { | |
1255 | char *debugfile; | |
1256 | ||
1257 | debugfile = find_separate_debug_file_by_buildid (objfile); | |
1258 | ||
1259 | if (debugfile == NULL) | |
1260 | debugfile = find_separate_debug_file_by_debuglink (objfile); | |
1261 | ||
1262 | if (debugfile) | |
1263 | { | |
1264 | struct cleanup *cleanup = make_cleanup (xfree, debugfile); | |
1265 | bfd *abfd = symfile_bfd_open (debugfile); | |
1266 | ||
1267 | make_cleanup_bfd_unref (abfd); | |
1268 | symbol_file_add_separate (abfd, debugfile, symfile_flags, objfile); | |
1269 | do_cleanups (cleanup); | |
1270 | } | |
1271 | } | |
1272 | } | |
1273 | ||
1274 | /* Callback to lazily read psymtabs. */ | |
1275 | ||
1276 | static void | |
1277 | read_psyms (struct objfile *objfile) | |
1278 | { | |
1279 | if (dwarf2_has_info (objfile, NULL)) | |
1280 | dwarf2_build_psymtabs (objfile); | |
1281 | } | |
1282 | ||
1283 | /* Initialize anything that needs initializing when a completely new symbol | |
1284 | file is specified (not just adding some symbols from another file, e.g. a | |
1285 | shared library). | |
1286 | ||
1287 | We reinitialize buildsym, since we may be reading stabs from an ELF | |
1288 | file. */ | |
1289 | ||
1290 | static void | |
1291 | elf_new_init (struct objfile *ignore) | |
1292 | { | |
1293 | stabsread_new_init (); | |
1294 | buildsym_new_init (); | |
1295 | } | |
1296 | ||
1297 | /* Perform any local cleanups required when we are done with a particular | |
1298 | objfile. I.E, we are in the process of discarding all symbol information | |
1299 | for an objfile, freeing up all memory held for it, and unlinking the | |
1300 | objfile struct from the global list of known objfiles. */ | |
1301 | ||
1302 | static void | |
1303 | elf_symfile_finish (struct objfile *objfile) | |
1304 | { | |
1305 | dwarf2_free_objfile (objfile); | |
1306 | } | |
1307 | ||
1308 | /* ELF specific initialization routine for reading symbols. */ | |
1309 | ||
1310 | static void | |
1311 | elf_symfile_init (struct objfile *objfile) | |
1312 | { | |
1313 | /* ELF objects may be reordered, so set OBJF_REORDERED. If we | |
1314 | find this causes a significant slowdown in gdb then we could | |
1315 | set it in the debug symbol readers only when necessary. */ | |
1316 | objfile->flags |= OBJF_REORDERED; | |
1317 | } | |
1318 | ||
1319 | /* Implementation of `sym_get_probes', as documented in symfile.h. */ | |
1320 | ||
1321 | static VEC (probe_p) * | |
1322 | elf_get_probes (struct objfile *objfile) | |
1323 | { | |
1324 | VEC (probe_p) *probes_per_bfd; | |
1325 | ||
1326 | /* Have we parsed this objfile's probes already? */ | |
1327 | probes_per_bfd = bfd_data (objfile->obfd, probe_key); | |
1328 | ||
1329 | if (!probes_per_bfd) | |
1330 | { | |
1331 | int ix; | |
1332 | const struct probe_ops *probe_ops; | |
1333 | ||
1334 | /* Here we try to gather information about all types of probes from the | |
1335 | objfile. */ | |
1336 | for (ix = 0; VEC_iterate (probe_ops_cp, all_probe_ops, ix, probe_ops); | |
1337 | ix++) | |
1338 | probe_ops->get_probes (&probes_per_bfd, objfile); | |
1339 | ||
1340 | if (probes_per_bfd == NULL) | |
1341 | { | |
1342 | VEC_reserve (probe_p, probes_per_bfd, 1); | |
1343 | gdb_assert (probes_per_bfd != NULL); | |
1344 | } | |
1345 | ||
1346 | set_bfd_data (objfile->obfd, probe_key, probes_per_bfd); | |
1347 | } | |
1348 | ||
1349 | return probes_per_bfd; | |
1350 | } | |
1351 | ||
1352 | /* Helper function used to free the space allocated for storing SystemTap | |
1353 | probe information. */ | |
1354 | ||
1355 | static void | |
1356 | probe_key_free (bfd *abfd, void *d) | |
1357 | { | |
1358 | int ix; | |
1359 | VEC (probe_p) *probes = d; | |
1360 | struct probe *probe; | |
1361 | ||
1362 | for (ix = 0; VEC_iterate (probe_p, probes, ix, probe); ix++) | |
1363 | probe->pops->destroy (probe); | |
1364 | ||
1365 | VEC_free (probe_p, probes); | |
1366 | } | |
1367 | ||
1368 | \f | |
1369 | ||
1370 | /* Implementation `sym_probe_fns', as documented in symfile.h. */ | |
1371 | ||
1372 | static const struct sym_probe_fns elf_probe_fns = | |
1373 | { | |
1374 | elf_get_probes, /* sym_get_probes */ | |
1375 | }; | |
1376 | ||
1377 | /* Register that we are able to handle ELF object file formats. */ | |
1378 | ||
1379 | static const struct sym_fns elf_sym_fns = | |
1380 | { | |
1381 | elf_new_init, /* init anything gbl to entire symtab */ | |
1382 | elf_symfile_init, /* read initial info, setup for sym_read() */ | |
1383 | elf_symfile_read, /* read a symbol file into symtab */ | |
1384 | NULL, /* sym_read_psymbols */ | |
1385 | elf_symfile_finish, /* finished with file, cleanup */ | |
1386 | default_symfile_offsets, /* Translate ext. to int. relocation */ | |
1387 | elf_symfile_segments, /* Get segment information from a file. */ | |
1388 | NULL, | |
1389 | default_symfile_relocate, /* Relocate a debug section. */ | |
1390 | &elf_probe_fns, /* sym_probe_fns */ | |
1391 | &psym_functions | |
1392 | }; | |
1393 | ||
1394 | /* The same as elf_sym_fns, but not registered and lazily reads | |
1395 | psymbols. */ | |
1396 | ||
1397 | const struct sym_fns elf_sym_fns_lazy_psyms = | |
1398 | { | |
1399 | elf_new_init, /* init anything gbl to entire symtab */ | |
1400 | elf_symfile_init, /* read initial info, setup for sym_read() */ | |
1401 | elf_symfile_read, /* read a symbol file into symtab */ | |
1402 | read_psyms, /* sym_read_psymbols */ | |
1403 | elf_symfile_finish, /* finished with file, cleanup */ | |
1404 | default_symfile_offsets, /* Translate ext. to int. relocation */ | |
1405 | elf_symfile_segments, /* Get segment information from a file. */ | |
1406 | NULL, | |
1407 | default_symfile_relocate, /* Relocate a debug section. */ | |
1408 | &elf_probe_fns, /* sym_probe_fns */ | |
1409 | &psym_functions | |
1410 | }; | |
1411 | ||
1412 | /* The same as elf_sym_fns, but not registered and uses the | |
1413 | DWARF-specific GNU index rather than psymtab. */ | |
1414 | const struct sym_fns elf_sym_fns_gdb_index = | |
1415 | { | |
1416 | elf_new_init, /* init anything gbl to entire symab */ | |
1417 | elf_symfile_init, /* read initial info, setup for sym_red() */ | |
1418 | elf_symfile_read, /* read a symbol file into symtab */ | |
1419 | NULL, /* sym_read_psymbols */ | |
1420 | elf_symfile_finish, /* finished with file, cleanup */ | |
1421 | default_symfile_offsets, /* Translate ext. to int. relocatin */ | |
1422 | elf_symfile_segments, /* Get segment information from a file. */ | |
1423 | NULL, | |
1424 | default_symfile_relocate, /* Relocate a debug section. */ | |
1425 | &elf_probe_fns, /* sym_probe_fns */ | |
1426 | &dwarf2_gdb_index_functions | |
1427 | }; | |
1428 | ||
1429 | /* STT_GNU_IFUNC resolver vector to be installed to gnu_ifunc_fns_p. */ | |
1430 | ||
1431 | static const struct gnu_ifunc_fns elf_gnu_ifunc_fns = | |
1432 | { | |
1433 | elf_gnu_ifunc_resolve_addr, | |
1434 | elf_gnu_ifunc_resolve_name, | |
1435 | elf_gnu_ifunc_resolver_stop, | |
1436 | elf_gnu_ifunc_resolver_return_stop | |
1437 | }; | |
1438 | ||
1439 | void | |
1440 | _initialize_elfread (void) | |
1441 | { | |
1442 | probe_key = register_bfd_data_with_cleanup (NULL, probe_key_free); | |
1443 | add_symtab_fns (bfd_target_elf_flavour, &elf_sym_fns); | |
1444 | ||
1445 | elf_objfile_gnu_ifunc_cache_data = register_objfile_data (); | |
1446 | gnu_ifunc_fns_p = &elf_gnu_ifunc_fns; | |
1447 | } |