| 1 | /* Read ELF (Executable and Linking Format) object files for GDB. |
| 2 | |
| 3 | Copyright (C) 1991-2019 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 "stabsread.h" |
| 32 | #include "gdb-stabs.h" |
| 33 | #include "complaints.h" |
| 34 | #include "demangle.h" |
| 35 | #include "psympriv.h" |
| 36 | #include "filenames.h" |
| 37 | #include "probe.h" |
| 38 | #include "arch-utils.h" |
| 39 | #include "gdbtypes.h" |
| 40 | #include "value.h" |
| 41 | #include "infcall.h" |
| 42 | #include "gdbthread.h" |
| 43 | #include "inferior.h" |
| 44 | #include "regcache.h" |
| 45 | #include "bcache.h" |
| 46 | #include "gdb_bfd.h" |
| 47 | #include "build-id.h" |
| 48 | #include "location.h" |
| 49 | #include "auxv.h" |
| 50 | |
| 51 | /* Forward declarations. */ |
| 52 | extern const struct sym_fns elf_sym_fns_gdb_index; |
| 53 | extern const struct sym_fns elf_sym_fns_debug_names; |
| 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 = (Elf_Internal_Phdr *) 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 = XALLOCAVEC (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 | |
| 124 | if ((bfd_get_section_flags (abfd, sect) & SEC_ALLOC) == 0) |
| 125 | continue; |
| 126 | |
| 127 | Elf_Internal_Shdr *this_hdr = &elf_section_data (sect)->this_hdr; |
| 128 | |
| 129 | for (j = 0; j < num_segments; j++) |
| 130 | if (ELF_SECTION_IN_SEGMENT (this_hdr, segments[j])) |
| 131 | { |
| 132 | data->segment_info[i] = j + 1; |
| 133 | break; |
| 134 | } |
| 135 | |
| 136 | /* We should have found a segment for every non-empty section. |
| 137 | If we haven't, we will not relocate this section by any |
| 138 | offsets we apply to the segments. As an exception, do not |
| 139 | warn about SHT_NOBITS sections; in normal ELF execution |
| 140 | environments, SHT_NOBITS means zero-initialized and belongs |
| 141 | in a segment, but in no-OS environments some tools (e.g. ARM |
| 142 | RealView) use SHT_NOBITS for uninitialized data. Since it is |
| 143 | uninitialized, it doesn't need a program header. Such |
| 144 | binaries are not relocatable. */ |
| 145 | if (bfd_get_section_size (sect) > 0 && j == num_segments |
| 146 | && (bfd_get_section_flags (abfd, sect) & SEC_LOAD) != 0) |
| 147 | warning (_("Loadable section \"%s\" outside of ELF segments"), |
| 148 | bfd_section_name (abfd, sect)); |
| 149 | } |
| 150 | |
| 151 | return data; |
| 152 | } |
| 153 | |
| 154 | /* We are called once per section from elf_symfile_read. We |
| 155 | need to examine each section we are passed, check to see |
| 156 | if it is something we are interested in processing, and |
| 157 | if so, stash away some access information for the section. |
| 158 | |
| 159 | For now we recognize the dwarf debug information sections and |
| 160 | line number sections from matching their section names. The |
| 161 | ELF definition is no real help here since it has no direct |
| 162 | knowledge of DWARF (by design, so any debugging format can be |
| 163 | used). |
| 164 | |
| 165 | We also recognize the ".stab" sections used by the Sun compilers |
| 166 | released with Solaris 2. |
| 167 | |
| 168 | FIXME: The section names should not be hardwired strings (what |
| 169 | should they be? I don't think most object file formats have enough |
| 170 | section flags to specify what kind of debug section it is. |
| 171 | -kingdon). */ |
| 172 | |
| 173 | static void |
| 174 | elf_locate_sections (bfd *ignore_abfd, asection *sectp, void *eip) |
| 175 | { |
| 176 | struct elfinfo *ei; |
| 177 | |
| 178 | ei = (struct elfinfo *) eip; |
| 179 | if (strcmp (sectp->name, ".stab") == 0) |
| 180 | { |
| 181 | ei->stabsect = sectp; |
| 182 | } |
| 183 | else if (strcmp (sectp->name, ".mdebug") == 0) |
| 184 | { |
| 185 | ei->mdebugsect = sectp; |
| 186 | } |
| 187 | } |
| 188 | |
| 189 | static struct minimal_symbol * |
| 190 | record_minimal_symbol (minimal_symbol_reader &reader, |
| 191 | const char *name, int name_len, bool copy_name, |
| 192 | CORE_ADDR address, |
| 193 | enum minimal_symbol_type ms_type, |
| 194 | asection *bfd_section, struct objfile *objfile) |
| 195 | { |
| 196 | struct gdbarch *gdbarch = get_objfile_arch (objfile); |
| 197 | |
| 198 | if (ms_type == mst_text || ms_type == mst_file_text |
| 199 | || ms_type == mst_text_gnu_ifunc) |
| 200 | address = gdbarch_addr_bits_remove (gdbarch, address); |
| 201 | |
| 202 | return reader.record_full (name, name_len, copy_name, address, |
| 203 | ms_type, |
| 204 | gdb_bfd_section_index (objfile->obfd, |
| 205 | bfd_section)); |
| 206 | } |
| 207 | |
| 208 | /* Read the symbol table of an ELF file. |
| 209 | |
| 210 | Given an objfile, a symbol table, and a flag indicating whether the |
| 211 | symbol table contains regular, dynamic, or synthetic symbols, add all |
| 212 | the global function and data symbols to the minimal symbol table. |
| 213 | |
| 214 | In stabs-in-ELF, as implemented by Sun, there are some local symbols |
| 215 | defined in the ELF symbol table, which can be used to locate |
| 216 | the beginnings of sections from each ".o" file that was linked to |
| 217 | form the executable objfile. We gather any such info and record it |
| 218 | in data structures hung off the objfile's private data. */ |
| 219 | |
| 220 | #define ST_REGULAR 0 |
| 221 | #define ST_DYNAMIC 1 |
| 222 | #define ST_SYNTHETIC 2 |
| 223 | |
| 224 | static void |
| 225 | elf_symtab_read (minimal_symbol_reader &reader, |
| 226 | struct objfile *objfile, int type, |
| 227 | long number_of_symbols, asymbol **symbol_table, |
| 228 | bool copy_names) |
| 229 | { |
| 230 | struct gdbarch *gdbarch = get_objfile_arch (objfile); |
| 231 | asymbol *sym; |
| 232 | long i; |
| 233 | CORE_ADDR symaddr; |
| 234 | enum minimal_symbol_type ms_type; |
| 235 | /* Name of the last file symbol. This is either a constant string or is |
| 236 | saved on the objfile's filename cache. */ |
| 237 | const char *filesymname = ""; |
| 238 | int stripped = (bfd_get_symcount (objfile->obfd) == 0); |
| 239 | int elf_make_msymbol_special_p |
| 240 | = gdbarch_elf_make_msymbol_special_p (gdbarch); |
| 241 | |
| 242 | for (i = 0; i < number_of_symbols; i++) |
| 243 | { |
| 244 | sym = symbol_table[i]; |
| 245 | if (sym->name == NULL || *sym->name == '\0') |
| 246 | { |
| 247 | /* Skip names that don't exist (shouldn't happen), or names |
| 248 | that are null strings (may happen). */ |
| 249 | continue; |
| 250 | } |
| 251 | |
| 252 | /* Skip "special" symbols, e.g. ARM mapping symbols. These are |
| 253 | symbols which do not correspond to objects in the symbol table, |
| 254 | but have some other target-specific meaning. */ |
| 255 | if (bfd_is_target_special_symbol (objfile->obfd, sym)) |
| 256 | { |
| 257 | if (gdbarch_record_special_symbol_p (gdbarch)) |
| 258 | gdbarch_record_special_symbol (gdbarch, objfile, sym); |
| 259 | continue; |
| 260 | } |
| 261 | |
| 262 | if (type == ST_DYNAMIC |
| 263 | && sym->section == bfd_und_section_ptr |
| 264 | && (sym->flags & BSF_FUNCTION)) |
| 265 | { |
| 266 | struct minimal_symbol *msym; |
| 267 | bfd *abfd = objfile->obfd; |
| 268 | asection *sect; |
| 269 | |
| 270 | /* Symbol is a reference to a function defined in |
| 271 | a shared library. |
| 272 | If its value is non zero then it is usually the address |
| 273 | of the corresponding entry in the procedure linkage table, |
| 274 | plus the desired section offset. |
| 275 | If its value is zero then the dynamic linker has to resolve |
| 276 | the symbol. We are unable to find any meaningful address |
| 277 | for this symbol in the executable file, so we skip it. */ |
| 278 | symaddr = sym->value; |
| 279 | if (symaddr == 0) |
| 280 | continue; |
| 281 | |
| 282 | /* sym->section is the undefined section. However, we want to |
| 283 | record the section where the PLT stub resides with the |
| 284 | minimal symbol. Search the section table for the one that |
| 285 | covers the stub's address. */ |
| 286 | for (sect = abfd->sections; sect != NULL; sect = sect->next) |
| 287 | { |
| 288 | if ((bfd_get_section_flags (abfd, sect) & SEC_ALLOC) == 0) |
| 289 | continue; |
| 290 | |
| 291 | if (symaddr >= bfd_get_section_vma (abfd, sect) |
| 292 | && symaddr < bfd_get_section_vma (abfd, sect) |
| 293 | + bfd_get_section_size (sect)) |
| 294 | break; |
| 295 | } |
| 296 | if (!sect) |
| 297 | continue; |
| 298 | |
| 299 | /* On ia64-hpux, we have discovered that the system linker |
| 300 | adds undefined symbols with nonzero addresses that cannot |
| 301 | be right (their address points inside the code of another |
| 302 | function in the .text section). This creates problems |
| 303 | when trying to determine which symbol corresponds to |
| 304 | a given address. |
| 305 | |
| 306 | We try to detect those buggy symbols by checking which |
| 307 | section we think they correspond to. Normally, PLT symbols |
| 308 | are stored inside their own section, and the typical name |
| 309 | for that section is ".plt". So, if there is a ".plt" |
| 310 | section, and yet the section name of our symbol does not |
| 311 | start with ".plt", we ignore that symbol. */ |
| 312 | if (!startswith (sect->name, ".plt") |
| 313 | && bfd_get_section_by_name (abfd, ".plt") != NULL) |
| 314 | continue; |
| 315 | |
| 316 | msym = record_minimal_symbol |
| 317 | (reader, sym->name, strlen (sym->name), copy_names, |
| 318 | symaddr, mst_solib_trampoline, sect, objfile); |
| 319 | if (msym != NULL) |
| 320 | { |
| 321 | msym->filename = filesymname; |
| 322 | if (elf_make_msymbol_special_p) |
| 323 | gdbarch_elf_make_msymbol_special (gdbarch, sym, msym); |
| 324 | } |
| 325 | continue; |
| 326 | } |
| 327 | |
| 328 | /* If it is a nonstripped executable, do not enter dynamic |
| 329 | symbols, as the dynamic symbol table is usually a subset |
| 330 | of the main symbol table. */ |
| 331 | if (type == ST_DYNAMIC && !stripped) |
| 332 | continue; |
| 333 | if (sym->flags & BSF_FILE) |
| 334 | { |
| 335 | filesymname |
| 336 | = (const char *) bcache (sym->name, strlen (sym->name) + 1, |
| 337 | objfile->per_bfd->filename_cache); |
| 338 | } |
| 339 | else if (sym->flags & BSF_SECTION_SYM) |
| 340 | continue; |
| 341 | else if (sym->flags & (BSF_GLOBAL | BSF_LOCAL | BSF_WEAK |
| 342 | | BSF_GNU_UNIQUE)) |
| 343 | { |
| 344 | struct minimal_symbol *msym; |
| 345 | |
| 346 | /* Select global/local/weak symbols. Note that bfd puts abs |
| 347 | symbols in their own section, so all symbols we are |
| 348 | interested in will have a section. */ |
| 349 | /* Bfd symbols are section relative. */ |
| 350 | symaddr = sym->value + sym->section->vma; |
| 351 | /* For non-absolute symbols, use the type of the section |
| 352 | they are relative to, to intuit text/data. Bfd provides |
| 353 | no way of figuring this out for absolute symbols. */ |
| 354 | if (sym->section == bfd_abs_section_ptr) |
| 355 | { |
| 356 | /* This is a hack to get the minimal symbol type |
| 357 | right for Irix 5, which has absolute addresses |
| 358 | with special section indices for dynamic symbols. |
| 359 | |
| 360 | NOTE: uweigand-20071112: Synthetic symbols do not |
| 361 | have an ELF-private part, so do not touch those. */ |
| 362 | unsigned int shndx = type == ST_SYNTHETIC ? 0 : |
| 363 | ((elf_symbol_type *) sym)->internal_elf_sym.st_shndx; |
| 364 | |
| 365 | switch (shndx) |
| 366 | { |
| 367 | case SHN_MIPS_TEXT: |
| 368 | ms_type = mst_text; |
| 369 | break; |
| 370 | case SHN_MIPS_DATA: |
| 371 | ms_type = mst_data; |
| 372 | break; |
| 373 | case SHN_MIPS_ACOMMON: |
| 374 | ms_type = mst_bss; |
| 375 | break; |
| 376 | default: |
| 377 | ms_type = mst_abs; |
| 378 | } |
| 379 | |
| 380 | /* If it is an Irix dynamic symbol, skip section name |
| 381 | symbols, relocate all others by section offset. */ |
| 382 | if (ms_type != mst_abs) |
| 383 | { |
| 384 | if (sym->name[0] == '.') |
| 385 | continue; |
| 386 | } |
| 387 | } |
| 388 | else if (sym->section->flags & SEC_CODE) |
| 389 | { |
| 390 | if (sym->flags & (BSF_GLOBAL | BSF_WEAK | BSF_GNU_UNIQUE)) |
| 391 | { |
| 392 | if (sym->flags & BSF_GNU_INDIRECT_FUNCTION) |
| 393 | ms_type = mst_text_gnu_ifunc; |
| 394 | else |
| 395 | ms_type = mst_text; |
| 396 | } |
| 397 | /* The BSF_SYNTHETIC check is there to omit ppc64 function |
| 398 | descriptors mistaken for static functions starting with 'L'. |
| 399 | */ |
| 400 | else if ((sym->name[0] == '.' && sym->name[1] == 'L' |
| 401 | && (sym->flags & BSF_SYNTHETIC) == 0) |
| 402 | || ((sym->flags & BSF_LOCAL) |
| 403 | && sym->name[0] == '$' |
| 404 | && sym->name[1] == 'L')) |
| 405 | /* Looks like a compiler-generated label. Skip |
| 406 | it. The assembler should be skipping these (to |
| 407 | keep executables small), but apparently with |
| 408 | gcc on the (deleted) delta m88k SVR4, it loses. |
| 409 | So to have us check too should be harmless (but |
| 410 | I encourage people to fix this in the assembler |
| 411 | instead of adding checks here). */ |
| 412 | continue; |
| 413 | else |
| 414 | { |
| 415 | ms_type = mst_file_text; |
| 416 | } |
| 417 | } |
| 418 | else if (sym->section->flags & SEC_ALLOC) |
| 419 | { |
| 420 | if (sym->flags & (BSF_GLOBAL | BSF_WEAK | BSF_GNU_UNIQUE)) |
| 421 | { |
| 422 | if (sym->flags & BSF_GNU_INDIRECT_FUNCTION) |
| 423 | { |
| 424 | ms_type = mst_data_gnu_ifunc; |
| 425 | } |
| 426 | else if (sym->section->flags & SEC_LOAD) |
| 427 | { |
| 428 | ms_type = mst_data; |
| 429 | } |
| 430 | else |
| 431 | { |
| 432 | ms_type = mst_bss; |
| 433 | } |
| 434 | } |
| 435 | else if (sym->flags & BSF_LOCAL) |
| 436 | { |
| 437 | if (sym->section->flags & SEC_LOAD) |
| 438 | { |
| 439 | ms_type = mst_file_data; |
| 440 | } |
| 441 | else |
| 442 | { |
| 443 | ms_type = mst_file_bss; |
| 444 | } |
| 445 | } |
| 446 | else |
| 447 | { |
| 448 | ms_type = mst_unknown; |
| 449 | } |
| 450 | } |
| 451 | else |
| 452 | { |
| 453 | /* FIXME: Solaris2 shared libraries include lots of |
| 454 | odd "absolute" and "undefined" symbols, that play |
| 455 | hob with actions like finding what function the PC |
| 456 | is in. Ignore them if they aren't text, data, or bss. */ |
| 457 | /* ms_type = mst_unknown; */ |
| 458 | continue; /* Skip this symbol. */ |
| 459 | } |
| 460 | msym = record_minimal_symbol |
| 461 | (reader, sym->name, strlen (sym->name), copy_names, symaddr, |
| 462 | ms_type, sym->section, objfile); |
| 463 | |
| 464 | if (msym) |
| 465 | { |
| 466 | /* NOTE: uweigand-20071112: A synthetic symbol does not have an |
| 467 | ELF-private part. */ |
| 468 | if (type != ST_SYNTHETIC) |
| 469 | { |
| 470 | /* Pass symbol size field in via BFD. FIXME!!! */ |
| 471 | elf_symbol_type *elf_sym = (elf_symbol_type *) sym; |
| 472 | SET_MSYMBOL_SIZE (msym, elf_sym->internal_elf_sym.st_size); |
| 473 | } |
| 474 | |
| 475 | msym->filename = filesymname; |
| 476 | if (elf_make_msymbol_special_p) |
| 477 | gdbarch_elf_make_msymbol_special (gdbarch, sym, msym); |
| 478 | } |
| 479 | |
| 480 | /* If we see a default versioned symbol, install it under |
| 481 | its version-less name. */ |
| 482 | if (msym != NULL) |
| 483 | { |
| 484 | const char *atsign = strchr (sym->name, '@'); |
| 485 | |
| 486 | if (atsign != NULL && atsign[1] == '@' && atsign > sym->name) |
| 487 | { |
| 488 | int len = atsign - sym->name; |
| 489 | |
| 490 | record_minimal_symbol (reader, sym->name, len, true, symaddr, |
| 491 | ms_type, sym->section, objfile); |
| 492 | } |
| 493 | } |
| 494 | |
| 495 | /* For @plt symbols, also record a trampoline to the |
| 496 | destination symbol. The @plt symbol will be used in |
| 497 | disassembly, and the trampoline will be used when we are |
| 498 | trying to find the target. */ |
| 499 | if (msym && ms_type == mst_text && type == ST_SYNTHETIC) |
| 500 | { |
| 501 | int len = strlen (sym->name); |
| 502 | |
| 503 | if (len > 4 && strcmp (sym->name + len - 4, "@plt") == 0) |
| 504 | { |
| 505 | struct minimal_symbol *mtramp; |
| 506 | |
| 507 | mtramp = record_minimal_symbol (reader, sym->name, len - 4, |
| 508 | true, symaddr, |
| 509 | mst_solib_trampoline, |
| 510 | sym->section, objfile); |
| 511 | if (mtramp) |
| 512 | { |
| 513 | SET_MSYMBOL_SIZE (mtramp, MSYMBOL_SIZE (msym)); |
| 514 | mtramp->created_by_gdb = 1; |
| 515 | mtramp->filename = filesymname; |
| 516 | if (elf_make_msymbol_special_p) |
| 517 | gdbarch_elf_make_msymbol_special (gdbarch, |
| 518 | sym, mtramp); |
| 519 | } |
| 520 | } |
| 521 | } |
| 522 | } |
| 523 | } |
| 524 | } |
| 525 | |
| 526 | /* Build minimal symbols named `function@got.plt' (see SYMBOL_GOT_PLT_SUFFIX) |
| 527 | for later look ups of which function to call when user requests |
| 528 | a STT_GNU_IFUNC function. As the STT_GNU_IFUNC type is found at the target |
| 529 | library defining `function' we cannot yet know while reading OBJFILE which |
| 530 | of the SYMBOL_GOT_PLT_SUFFIX entries will be needed and later |
| 531 | DYN_SYMBOL_TABLE is no longer easily available for OBJFILE. */ |
| 532 | |
| 533 | static void |
| 534 | elf_rel_plt_read (minimal_symbol_reader &reader, |
| 535 | 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 *relplt, *got_plt; |
| 540 | bfd_size_type reloc_count, reloc; |
| 541 | struct gdbarch *gdbarch = get_objfile_arch (objfile); |
| 542 | struct type *ptr_type = builtin_type (gdbarch)->builtin_data_ptr; |
| 543 | size_t ptr_size = TYPE_LENGTH (ptr_type); |
| 544 | |
| 545 | if (objfile->separate_debug_objfile_backlink) |
| 546 | return; |
| 547 | |
| 548 | got_plt = bfd_get_section_by_name (obfd, ".got.plt"); |
| 549 | if (got_plt == NULL) |
| 550 | { |
| 551 | /* For platforms where there is no separate .got.plt. */ |
| 552 | got_plt = bfd_get_section_by_name (obfd, ".got"); |
| 553 | if (got_plt == NULL) |
| 554 | return; |
| 555 | } |
| 556 | |
| 557 | /* Depending on system, we may find jump slots in a relocation |
| 558 | section for either .got.plt or .plt. */ |
| 559 | asection *plt = bfd_get_section_by_name (obfd, ".plt"); |
| 560 | int plt_elf_idx = (plt != NULL) ? elf_section_data (plt)->this_idx : -1; |
| 561 | |
| 562 | int got_plt_elf_idx = elf_section_data (got_plt)->this_idx; |
| 563 | |
| 564 | /* This search algorithm is from _bfd_elf_canonicalize_dynamic_reloc. */ |
| 565 | for (relplt = obfd->sections; relplt != NULL; relplt = relplt->next) |
| 566 | { |
| 567 | const auto &this_hdr = elf_section_data (relplt)->this_hdr; |
| 568 | |
| 569 | if (this_hdr.sh_type == SHT_REL || this_hdr.sh_type == SHT_RELA) |
| 570 | { |
| 571 | if (this_hdr.sh_info == plt_elf_idx |
| 572 | || this_hdr.sh_info == got_plt_elf_idx) |
| 573 | break; |
| 574 | } |
| 575 | } |
| 576 | if (relplt == NULL) |
| 577 | return; |
| 578 | |
| 579 | if (! bed->s->slurp_reloc_table (obfd, relplt, dyn_symbol_table, TRUE)) |
| 580 | return; |
| 581 | |
| 582 | std::string string_buffer; |
| 583 | |
| 584 | /* Does ADDRESS reside in SECTION of OBFD? */ |
| 585 | auto within_section = [obfd] (asection *section, CORE_ADDR address) |
| 586 | { |
| 587 | if (section == NULL) |
| 588 | return false; |
| 589 | |
| 590 | return (bfd_get_section_vma (obfd, section) <= address |
| 591 | && (address < bfd_get_section_vma (obfd, section) |
| 592 | + bfd_get_section_size (section))); |
| 593 | }; |
| 594 | |
| 595 | reloc_count = relplt->size / elf_section_data (relplt)->this_hdr.sh_entsize; |
| 596 | for (reloc = 0; reloc < reloc_count; reloc++) |
| 597 | { |
| 598 | const char *name; |
| 599 | struct minimal_symbol *msym; |
| 600 | CORE_ADDR address; |
| 601 | const char *got_suffix = SYMBOL_GOT_PLT_SUFFIX; |
| 602 | const size_t got_suffix_len = strlen (SYMBOL_GOT_PLT_SUFFIX); |
| 603 | |
| 604 | name = bfd_asymbol_name (*relplt->relocation[reloc].sym_ptr_ptr); |
| 605 | address = relplt->relocation[reloc].address; |
| 606 | |
| 607 | asection *msym_section; |
| 608 | |
| 609 | /* Does the pointer reside in either the .got.plt or .plt |
| 610 | sections? */ |
| 611 | if (within_section (got_plt, address)) |
| 612 | msym_section = got_plt; |
| 613 | else if (within_section (plt, address)) |
| 614 | msym_section = plt; |
| 615 | else |
| 616 | continue; |
| 617 | |
| 618 | /* We cannot check if NAME is a reference to |
| 619 | mst_text_gnu_ifunc/mst_data_gnu_ifunc as in OBJFILE the |
| 620 | symbol is undefined and the objfile having NAME defined may |
| 621 | not yet have been loaded. */ |
| 622 | |
| 623 | string_buffer.assign (name); |
| 624 | string_buffer.append (got_suffix, got_suffix + got_suffix_len); |
| 625 | |
| 626 | msym = record_minimal_symbol (reader, string_buffer.c_str (), |
| 627 | string_buffer.size (), |
| 628 | true, address, mst_slot_got_plt, |
| 629 | msym_section, objfile); |
| 630 | if (msym) |
| 631 | SET_MSYMBOL_SIZE (msym, ptr_size); |
| 632 | } |
| 633 | } |
| 634 | |
| 635 | /* The data pointer is htab_t for gnu_ifunc_record_cache_unchecked. */ |
| 636 | |
| 637 | static const struct objfile_data *elf_objfile_gnu_ifunc_cache_data; |
| 638 | |
| 639 | /* Map function names to CORE_ADDR in elf_objfile_gnu_ifunc_cache_data. */ |
| 640 | |
| 641 | struct elf_gnu_ifunc_cache |
| 642 | { |
| 643 | /* This is always a function entry address, not a function descriptor. */ |
| 644 | CORE_ADDR addr; |
| 645 | |
| 646 | char name[1]; |
| 647 | }; |
| 648 | |
| 649 | /* htab_hash for elf_objfile_gnu_ifunc_cache_data. */ |
| 650 | |
| 651 | static hashval_t |
| 652 | elf_gnu_ifunc_cache_hash (const void *a_voidp) |
| 653 | { |
| 654 | const struct elf_gnu_ifunc_cache *a |
| 655 | = (const struct elf_gnu_ifunc_cache *) a_voidp; |
| 656 | |
| 657 | return htab_hash_string (a->name); |
| 658 | } |
| 659 | |
| 660 | /* htab_eq for elf_objfile_gnu_ifunc_cache_data. */ |
| 661 | |
| 662 | static int |
| 663 | elf_gnu_ifunc_cache_eq (const void *a_voidp, const void *b_voidp) |
| 664 | { |
| 665 | const struct elf_gnu_ifunc_cache *a |
| 666 | = (const struct elf_gnu_ifunc_cache *) a_voidp; |
| 667 | const struct elf_gnu_ifunc_cache *b |
| 668 | = (const struct elf_gnu_ifunc_cache *) b_voidp; |
| 669 | |
| 670 | return strcmp (a->name, b->name) == 0; |
| 671 | } |
| 672 | |
| 673 | /* Record the target function address of a STT_GNU_IFUNC function NAME is the |
| 674 | function entry address ADDR. Return 1 if NAME and ADDR are considered as |
| 675 | valid and therefore they were successfully recorded, return 0 otherwise. |
| 676 | |
| 677 | Function does not expect a duplicate entry. Use |
| 678 | elf_gnu_ifunc_resolve_by_cache first to check if the entry for NAME already |
| 679 | exists. */ |
| 680 | |
| 681 | static int |
| 682 | elf_gnu_ifunc_record_cache (const char *name, CORE_ADDR addr) |
| 683 | { |
| 684 | struct bound_minimal_symbol msym; |
| 685 | struct objfile *objfile; |
| 686 | htab_t htab; |
| 687 | struct elf_gnu_ifunc_cache entry_local, *entry_p; |
| 688 | void **slot; |
| 689 | |
| 690 | msym = lookup_minimal_symbol_by_pc (addr); |
| 691 | if (msym.minsym == NULL) |
| 692 | return 0; |
| 693 | if (BMSYMBOL_VALUE_ADDRESS (msym) != addr) |
| 694 | return 0; |
| 695 | objfile = msym.objfile; |
| 696 | |
| 697 | /* If .plt jumps back to .plt the symbol is still deferred for later |
| 698 | resolution and it has no use for GDB. */ |
| 699 | const char *target_name = MSYMBOL_LINKAGE_NAME (msym.minsym); |
| 700 | size_t len = strlen (target_name); |
| 701 | |
| 702 | /* Note we check the symbol's name instead of checking whether the |
| 703 | symbol is in the .plt section because some systems have @plt |
| 704 | symbols in the .text section. */ |
| 705 | if (len > 4 && strcmp (target_name + len - 4, "@plt") == 0) |
| 706 | return 0; |
| 707 | |
| 708 | htab = (htab_t) objfile_data (objfile, elf_objfile_gnu_ifunc_cache_data); |
| 709 | if (htab == NULL) |
| 710 | { |
| 711 | htab = htab_create_alloc_ex (1, elf_gnu_ifunc_cache_hash, |
| 712 | elf_gnu_ifunc_cache_eq, |
| 713 | NULL, &objfile->objfile_obstack, |
| 714 | hashtab_obstack_allocate, |
| 715 | dummy_obstack_deallocate); |
| 716 | set_objfile_data (objfile, elf_objfile_gnu_ifunc_cache_data, htab); |
| 717 | } |
| 718 | |
| 719 | entry_local.addr = addr; |
| 720 | obstack_grow (&objfile->objfile_obstack, &entry_local, |
| 721 | offsetof (struct elf_gnu_ifunc_cache, name)); |
| 722 | obstack_grow_str0 (&objfile->objfile_obstack, name); |
| 723 | entry_p |
| 724 | = (struct elf_gnu_ifunc_cache *) obstack_finish (&objfile->objfile_obstack); |
| 725 | |
| 726 | slot = htab_find_slot (htab, entry_p, INSERT); |
| 727 | if (*slot != NULL) |
| 728 | { |
| 729 | struct elf_gnu_ifunc_cache *entry_found_p |
| 730 | = (struct elf_gnu_ifunc_cache *) *slot; |
| 731 | struct gdbarch *gdbarch = get_objfile_arch (objfile); |
| 732 | |
| 733 | if (entry_found_p->addr != addr) |
| 734 | { |
| 735 | /* This case indicates buggy inferior program, the resolved address |
| 736 | should never change. */ |
| 737 | |
| 738 | warning (_("gnu-indirect-function \"%s\" has changed its resolved " |
| 739 | "function_address from %s to %s"), |
| 740 | name, paddress (gdbarch, entry_found_p->addr), |
| 741 | paddress (gdbarch, addr)); |
| 742 | } |
| 743 | |
| 744 | /* New ENTRY_P is here leaked/duplicate in the OBJFILE obstack. */ |
| 745 | } |
| 746 | *slot = entry_p; |
| 747 | |
| 748 | return 1; |
| 749 | } |
| 750 | |
| 751 | /* Try to find the target resolved function entry address of a STT_GNU_IFUNC |
| 752 | function NAME. If the address is found it is stored to *ADDR_P (if ADDR_P |
| 753 | is not NULL) and the function returns 1. It returns 0 otherwise. |
| 754 | |
| 755 | Only the elf_objfile_gnu_ifunc_cache_data hash table is searched by this |
| 756 | function. */ |
| 757 | |
| 758 | static int |
| 759 | elf_gnu_ifunc_resolve_by_cache (const char *name, CORE_ADDR *addr_p) |
| 760 | { |
| 761 | for (objfile *objfile : all_objfiles (current_program_space)) |
| 762 | { |
| 763 | htab_t htab; |
| 764 | struct elf_gnu_ifunc_cache *entry_p; |
| 765 | void **slot; |
| 766 | |
| 767 | htab = (htab_t) objfile_data (objfile, elf_objfile_gnu_ifunc_cache_data); |
| 768 | if (htab == NULL) |
| 769 | continue; |
| 770 | |
| 771 | entry_p = ((struct elf_gnu_ifunc_cache *) |
| 772 | alloca (sizeof (*entry_p) + strlen (name))); |
| 773 | strcpy (entry_p->name, name); |
| 774 | |
| 775 | slot = htab_find_slot (htab, entry_p, NO_INSERT); |
| 776 | if (slot == NULL) |
| 777 | continue; |
| 778 | entry_p = (struct elf_gnu_ifunc_cache *) *slot; |
| 779 | gdb_assert (entry_p != NULL); |
| 780 | |
| 781 | if (addr_p) |
| 782 | *addr_p = entry_p->addr; |
| 783 | return 1; |
| 784 | } |
| 785 | |
| 786 | return 0; |
| 787 | } |
| 788 | |
| 789 | /* Try to find the target resolved function entry address of a STT_GNU_IFUNC |
| 790 | function NAME. If the address is found it is stored to *ADDR_P (if ADDR_P |
| 791 | is not NULL) and the function returns 1. It returns 0 otherwise. |
| 792 | |
| 793 | Only the SYMBOL_GOT_PLT_SUFFIX locations are searched by this function. |
| 794 | elf_gnu_ifunc_resolve_by_cache must have been already called for NAME to |
| 795 | prevent cache entries duplicates. */ |
| 796 | |
| 797 | static int |
| 798 | elf_gnu_ifunc_resolve_by_got (const char *name, CORE_ADDR *addr_p) |
| 799 | { |
| 800 | char *name_got_plt; |
| 801 | const size_t got_suffix_len = strlen (SYMBOL_GOT_PLT_SUFFIX); |
| 802 | |
| 803 | name_got_plt = (char *) alloca (strlen (name) + got_suffix_len + 1); |
| 804 | sprintf (name_got_plt, "%s" SYMBOL_GOT_PLT_SUFFIX, name); |
| 805 | |
| 806 | for (objfile *objfile : all_objfiles (current_program_space)) |
| 807 | { |
| 808 | bfd *obfd = objfile->obfd; |
| 809 | struct gdbarch *gdbarch = get_objfile_arch (objfile); |
| 810 | struct type *ptr_type = builtin_type (gdbarch)->builtin_data_ptr; |
| 811 | size_t ptr_size = TYPE_LENGTH (ptr_type); |
| 812 | CORE_ADDR pointer_address, addr; |
| 813 | asection *plt; |
| 814 | gdb_byte *buf = (gdb_byte *) alloca (ptr_size); |
| 815 | struct bound_minimal_symbol msym; |
| 816 | |
| 817 | msym = lookup_minimal_symbol (name_got_plt, NULL, objfile); |
| 818 | if (msym.minsym == NULL) |
| 819 | continue; |
| 820 | if (MSYMBOL_TYPE (msym.minsym) != mst_slot_got_plt) |
| 821 | continue; |
| 822 | pointer_address = BMSYMBOL_VALUE_ADDRESS (msym); |
| 823 | |
| 824 | plt = bfd_get_section_by_name (obfd, ".plt"); |
| 825 | if (plt == NULL) |
| 826 | continue; |
| 827 | |
| 828 | if (MSYMBOL_SIZE (msym.minsym) != ptr_size) |
| 829 | continue; |
| 830 | if (target_read_memory (pointer_address, buf, ptr_size) != 0) |
| 831 | continue; |
| 832 | addr = extract_typed_address (buf, ptr_type); |
| 833 | addr = gdbarch_convert_from_func_ptr_addr (gdbarch, addr, |
| 834 | current_top_target ()); |
| 835 | addr = gdbarch_addr_bits_remove (gdbarch, addr); |
| 836 | |
| 837 | if (elf_gnu_ifunc_record_cache (name, addr)) |
| 838 | { |
| 839 | if (addr_p != NULL) |
| 840 | *addr_p = addr; |
| 841 | return 1; |
| 842 | } |
| 843 | } |
| 844 | |
| 845 | return 0; |
| 846 | } |
| 847 | |
| 848 | /* Try to find the target resolved function entry address of a STT_GNU_IFUNC |
| 849 | function NAME. If the address is found it is stored to *ADDR_P (if ADDR_P |
| 850 | is not NULL) and the function returns 1. It returns 0 otherwise. |
| 851 | |
| 852 | Both the elf_objfile_gnu_ifunc_cache_data hash table and |
| 853 | SYMBOL_GOT_PLT_SUFFIX locations are searched by this function. */ |
| 854 | |
| 855 | static int |
| 856 | elf_gnu_ifunc_resolve_name (const char *name, CORE_ADDR *addr_p) |
| 857 | { |
| 858 | if (elf_gnu_ifunc_resolve_by_cache (name, addr_p)) |
| 859 | return 1; |
| 860 | |
| 861 | if (elf_gnu_ifunc_resolve_by_got (name, addr_p)) |
| 862 | return 1; |
| 863 | |
| 864 | return 0; |
| 865 | } |
| 866 | |
| 867 | /* Call STT_GNU_IFUNC - a function returning addresss of a real function to |
| 868 | call. PC is theSTT_GNU_IFUNC resolving function entry. The value returned |
| 869 | is the entry point of the resolved STT_GNU_IFUNC target function to call. |
| 870 | */ |
| 871 | |
| 872 | static CORE_ADDR |
| 873 | elf_gnu_ifunc_resolve_addr (struct gdbarch *gdbarch, CORE_ADDR pc) |
| 874 | { |
| 875 | const char *name_at_pc; |
| 876 | CORE_ADDR start_at_pc, address; |
| 877 | struct type *func_func_type = builtin_type (gdbarch)->builtin_func_func; |
| 878 | struct value *function, *address_val; |
| 879 | CORE_ADDR hwcap = 0; |
| 880 | struct value *hwcap_val; |
| 881 | |
| 882 | /* Try first any non-intrusive methods without an inferior call. */ |
| 883 | |
| 884 | if (find_pc_partial_function (pc, &name_at_pc, &start_at_pc, NULL) |
| 885 | && start_at_pc == pc) |
| 886 | { |
| 887 | if (elf_gnu_ifunc_resolve_name (name_at_pc, &address)) |
| 888 | return address; |
| 889 | } |
| 890 | else |
| 891 | name_at_pc = NULL; |
| 892 | |
| 893 | function = allocate_value (func_func_type); |
| 894 | VALUE_LVAL (function) = lval_memory; |
| 895 | set_value_address (function, pc); |
| 896 | |
| 897 | /* STT_GNU_IFUNC resolver functions usually receive the HWCAP vector as |
| 898 | parameter. FUNCTION is the function entry address. ADDRESS may be a |
| 899 | function descriptor. */ |
| 900 | |
| 901 | target_auxv_search (current_top_target (), AT_HWCAP, &hwcap); |
| 902 | hwcap_val = value_from_longest (builtin_type (gdbarch) |
| 903 | ->builtin_unsigned_long, hwcap); |
| 904 | address_val = call_function_by_hand (function, NULL, hwcap_val); |
| 905 | address = value_as_address (address_val); |
| 906 | address = gdbarch_convert_from_func_ptr_addr (gdbarch, address, current_top_target ()); |
| 907 | address = gdbarch_addr_bits_remove (gdbarch, address); |
| 908 | |
| 909 | if (name_at_pc) |
| 910 | elf_gnu_ifunc_record_cache (name_at_pc, address); |
| 911 | |
| 912 | return address; |
| 913 | } |
| 914 | |
| 915 | /* Handle inferior hit of bp_gnu_ifunc_resolver, see its definition. */ |
| 916 | |
| 917 | static void |
| 918 | elf_gnu_ifunc_resolver_stop (struct breakpoint *b) |
| 919 | { |
| 920 | struct breakpoint *b_return; |
| 921 | struct frame_info *prev_frame = get_prev_frame (get_current_frame ()); |
| 922 | struct frame_id prev_frame_id = get_stack_frame_id (prev_frame); |
| 923 | CORE_ADDR prev_pc = get_frame_pc (prev_frame); |
| 924 | int thread_id = inferior_thread ()->global_num; |
| 925 | |
| 926 | gdb_assert (b->type == bp_gnu_ifunc_resolver); |
| 927 | |
| 928 | for (b_return = b->related_breakpoint; b_return != b; |
| 929 | b_return = b_return->related_breakpoint) |
| 930 | { |
| 931 | gdb_assert (b_return->type == bp_gnu_ifunc_resolver_return); |
| 932 | gdb_assert (b_return->loc != NULL && b_return->loc->next == NULL); |
| 933 | gdb_assert (frame_id_p (b_return->frame_id)); |
| 934 | |
| 935 | if (b_return->thread == thread_id |
| 936 | && b_return->loc->requested_address == prev_pc |
| 937 | && frame_id_eq (b_return->frame_id, prev_frame_id)) |
| 938 | break; |
| 939 | } |
| 940 | |
| 941 | if (b_return == b) |
| 942 | { |
| 943 | /* No need to call find_pc_line for symbols resolving as this is only |
| 944 | a helper breakpointer never shown to the user. */ |
| 945 | |
| 946 | symtab_and_line sal; |
| 947 | sal.pspace = current_inferior ()->pspace; |
| 948 | sal.pc = prev_pc; |
| 949 | sal.section = find_pc_overlay (sal.pc); |
| 950 | sal.explicit_pc = 1; |
| 951 | b_return |
| 952 | = set_momentary_breakpoint (get_frame_arch (prev_frame), sal, |
| 953 | prev_frame_id, |
| 954 | bp_gnu_ifunc_resolver_return).release (); |
| 955 | |
| 956 | /* set_momentary_breakpoint invalidates PREV_FRAME. */ |
| 957 | prev_frame = NULL; |
| 958 | |
| 959 | /* Add new b_return to the ring list b->related_breakpoint. */ |
| 960 | gdb_assert (b_return->related_breakpoint == b_return); |
| 961 | b_return->related_breakpoint = b->related_breakpoint; |
| 962 | b->related_breakpoint = b_return; |
| 963 | } |
| 964 | } |
| 965 | |
| 966 | /* Handle inferior hit of bp_gnu_ifunc_resolver_return, see its definition. */ |
| 967 | |
| 968 | static void |
| 969 | elf_gnu_ifunc_resolver_return_stop (struct breakpoint *b) |
| 970 | { |
| 971 | thread_info *thread = inferior_thread (); |
| 972 | struct gdbarch *gdbarch = get_frame_arch (get_current_frame ()); |
| 973 | struct type *func_func_type = builtin_type (gdbarch)->builtin_func_func; |
| 974 | struct type *value_type = TYPE_TARGET_TYPE (func_func_type); |
| 975 | struct regcache *regcache = get_thread_regcache (thread); |
| 976 | struct value *func_func; |
| 977 | struct value *value; |
| 978 | CORE_ADDR resolved_address, resolved_pc; |
| 979 | |
| 980 | gdb_assert (b->type == bp_gnu_ifunc_resolver_return); |
| 981 | |
| 982 | while (b->related_breakpoint != b) |
| 983 | { |
| 984 | struct breakpoint *b_next = b->related_breakpoint; |
| 985 | |
| 986 | switch (b->type) |
| 987 | { |
| 988 | case bp_gnu_ifunc_resolver: |
| 989 | break; |
| 990 | case bp_gnu_ifunc_resolver_return: |
| 991 | delete_breakpoint (b); |
| 992 | break; |
| 993 | default: |
| 994 | internal_error (__FILE__, __LINE__, |
| 995 | _("handle_inferior_event: Invalid " |
| 996 | "gnu-indirect-function breakpoint type %d"), |
| 997 | (int) b->type); |
| 998 | } |
| 999 | b = b_next; |
| 1000 | } |
| 1001 | gdb_assert (b->type == bp_gnu_ifunc_resolver); |
| 1002 | gdb_assert (b->loc->next == NULL); |
| 1003 | |
| 1004 | func_func = allocate_value (func_func_type); |
| 1005 | VALUE_LVAL (func_func) = lval_memory; |
| 1006 | set_value_address (func_func, b->loc->related_address); |
| 1007 | |
| 1008 | value = allocate_value (value_type); |
| 1009 | gdbarch_return_value (gdbarch, func_func, value_type, regcache, |
| 1010 | value_contents_raw (value), NULL); |
| 1011 | resolved_address = value_as_address (value); |
| 1012 | resolved_pc = gdbarch_convert_from_func_ptr_addr (gdbarch, |
| 1013 | resolved_address, |
| 1014 | current_top_target ()); |
| 1015 | resolved_pc = gdbarch_addr_bits_remove (gdbarch, resolved_pc); |
| 1016 | |
| 1017 | gdb_assert (current_program_space == b->pspace || b->pspace == NULL); |
| 1018 | elf_gnu_ifunc_record_cache (event_location_to_string (b->location.get ()), |
| 1019 | resolved_pc); |
| 1020 | |
| 1021 | b->type = bp_breakpoint; |
| 1022 | update_breakpoint_locations (b, current_program_space, |
| 1023 | find_function_start_sal (resolved_pc, NULL, true), |
| 1024 | {}); |
| 1025 | } |
| 1026 | |
| 1027 | /* A helper function for elf_symfile_read that reads the minimal |
| 1028 | symbols. */ |
| 1029 | |
| 1030 | static void |
| 1031 | elf_read_minimal_symbols (struct objfile *objfile, int symfile_flags, |
| 1032 | const struct elfinfo *ei) |
| 1033 | { |
| 1034 | bfd *synth_abfd, *abfd = objfile->obfd; |
| 1035 | long symcount = 0, dynsymcount = 0, synthcount, storage_needed; |
| 1036 | asymbol **symbol_table = NULL, **dyn_symbol_table = NULL; |
| 1037 | asymbol *synthsyms; |
| 1038 | struct dbx_symfile_info *dbx; |
| 1039 | |
| 1040 | if (symtab_create_debug) |
| 1041 | { |
| 1042 | fprintf_unfiltered (gdb_stdlog, |
| 1043 | "Reading minimal symbols of objfile %s ...\n", |
| 1044 | objfile_name (objfile)); |
| 1045 | } |
| 1046 | |
| 1047 | /* If we already have minsyms, then we can skip some work here. |
| 1048 | However, if there were stabs or mdebug sections, we go ahead and |
| 1049 | redo all the work anyway, because the psym readers for those |
| 1050 | kinds of debuginfo need extra information found here. This can |
| 1051 | go away once all types of symbols are in the per-BFD object. */ |
| 1052 | if (objfile->per_bfd->minsyms_read |
| 1053 | && ei->stabsect == NULL |
| 1054 | && ei->mdebugsect == NULL) |
| 1055 | { |
| 1056 | if (symtab_create_debug) |
| 1057 | fprintf_unfiltered (gdb_stdlog, |
| 1058 | "... minimal symbols previously read\n"); |
| 1059 | return; |
| 1060 | } |
| 1061 | |
| 1062 | minimal_symbol_reader reader (objfile); |
| 1063 | |
| 1064 | /* Allocate struct to keep track of the symfile. */ |
| 1065 | dbx = XCNEW (struct dbx_symfile_info); |
| 1066 | set_objfile_data (objfile, dbx_objfile_data_key, dbx); |
| 1067 | |
| 1068 | /* Process the normal ELF symbol table first. */ |
| 1069 | |
| 1070 | storage_needed = bfd_get_symtab_upper_bound (objfile->obfd); |
| 1071 | if (storage_needed < 0) |
| 1072 | error (_("Can't read symbols from %s: %s"), |
| 1073 | bfd_get_filename (objfile->obfd), |
| 1074 | bfd_errmsg (bfd_get_error ())); |
| 1075 | |
| 1076 | if (storage_needed > 0) |
| 1077 | { |
| 1078 | /* Memory gets permanently referenced from ABFD after |
| 1079 | bfd_canonicalize_symtab so it must not get freed before ABFD gets. */ |
| 1080 | |
| 1081 | symbol_table = (asymbol **) bfd_alloc (abfd, storage_needed); |
| 1082 | symcount = bfd_canonicalize_symtab (objfile->obfd, symbol_table); |
| 1083 | |
| 1084 | if (symcount < 0) |
| 1085 | error (_("Can't read symbols from %s: %s"), |
| 1086 | bfd_get_filename (objfile->obfd), |
| 1087 | bfd_errmsg (bfd_get_error ())); |
| 1088 | |
| 1089 | elf_symtab_read (reader, objfile, ST_REGULAR, symcount, symbol_table, |
| 1090 | false); |
| 1091 | } |
| 1092 | |
| 1093 | /* Add the dynamic symbols. */ |
| 1094 | |
| 1095 | storage_needed = bfd_get_dynamic_symtab_upper_bound (objfile->obfd); |
| 1096 | |
| 1097 | if (storage_needed > 0) |
| 1098 | { |
| 1099 | /* Memory gets permanently referenced from ABFD after |
| 1100 | bfd_get_synthetic_symtab so it must not get freed before ABFD gets. |
| 1101 | It happens only in the case when elf_slurp_reloc_table sees |
| 1102 | asection->relocation NULL. Determining which section is asection is |
| 1103 | done by _bfd_elf_get_synthetic_symtab which is all a bfd |
| 1104 | implementation detail, though. */ |
| 1105 | |
| 1106 | dyn_symbol_table = (asymbol **) bfd_alloc (abfd, storage_needed); |
| 1107 | dynsymcount = bfd_canonicalize_dynamic_symtab (objfile->obfd, |
| 1108 | dyn_symbol_table); |
| 1109 | |
| 1110 | if (dynsymcount < 0) |
| 1111 | error (_("Can't read symbols from %s: %s"), |
| 1112 | bfd_get_filename (objfile->obfd), |
| 1113 | bfd_errmsg (bfd_get_error ())); |
| 1114 | |
| 1115 | elf_symtab_read (reader, objfile, ST_DYNAMIC, dynsymcount, |
| 1116 | dyn_symbol_table, false); |
| 1117 | |
| 1118 | elf_rel_plt_read (reader, objfile, dyn_symbol_table); |
| 1119 | } |
| 1120 | |
| 1121 | /* Contrary to binutils --strip-debug/--only-keep-debug the strip command from |
| 1122 | elfutils (eu-strip) moves even the .symtab section into the .debug file. |
| 1123 | |
| 1124 | bfd_get_synthetic_symtab on ppc64 for each function descriptor ELF symbol |
| 1125 | 'name' creates a new BSF_SYNTHETIC ELF symbol '.name' with its code |
| 1126 | address. But with eu-strip files bfd_get_synthetic_symtab would fail to |
| 1127 | read the code address from .opd while it reads the .symtab section from |
| 1128 | a separate debug info file as the .opd section is SHT_NOBITS there. |
| 1129 | |
| 1130 | With SYNTH_ABFD the .opd section will be read from the original |
| 1131 | backlinked binary where it is valid. */ |
| 1132 | |
| 1133 | if (objfile->separate_debug_objfile_backlink) |
| 1134 | synth_abfd = objfile->separate_debug_objfile_backlink->obfd; |
| 1135 | else |
| 1136 | synth_abfd = abfd; |
| 1137 | |
| 1138 | /* Add synthetic symbols - for instance, names for any PLT entries. */ |
| 1139 | |
| 1140 | synthcount = bfd_get_synthetic_symtab (synth_abfd, symcount, symbol_table, |
| 1141 | dynsymcount, dyn_symbol_table, |
| 1142 | &synthsyms); |
| 1143 | if (synthcount > 0) |
| 1144 | { |
| 1145 | long i; |
| 1146 | |
| 1147 | std::unique_ptr<asymbol *[]> |
| 1148 | synth_symbol_table (new asymbol *[synthcount]); |
| 1149 | for (i = 0; i < synthcount; i++) |
| 1150 | synth_symbol_table[i] = synthsyms + i; |
| 1151 | elf_symtab_read (reader, objfile, ST_SYNTHETIC, synthcount, |
| 1152 | synth_symbol_table.get (), true); |
| 1153 | |
| 1154 | xfree (synthsyms); |
| 1155 | synthsyms = NULL; |
| 1156 | } |
| 1157 | |
| 1158 | /* Install any minimal symbols that have been collected as the current |
| 1159 | minimal symbols for this objfile. The debug readers below this point |
| 1160 | should not generate new minimal symbols; if they do it's their |
| 1161 | responsibility to install them. "mdebug" appears to be the only one |
| 1162 | which will do this. */ |
| 1163 | |
| 1164 | reader.install (); |
| 1165 | |
| 1166 | if (symtab_create_debug) |
| 1167 | fprintf_unfiltered (gdb_stdlog, "Done reading minimal symbols.\n"); |
| 1168 | } |
| 1169 | |
| 1170 | /* Scan and build partial symbols for a symbol file. |
| 1171 | We have been initialized by a call to elf_symfile_init, which |
| 1172 | currently does nothing. |
| 1173 | |
| 1174 | This function only does the minimum work necessary for letting the |
| 1175 | user "name" things symbolically; it does not read the entire symtab. |
| 1176 | Instead, it reads the external and static symbols and puts them in partial |
| 1177 | symbol tables. When more extensive information is requested of a |
| 1178 | file, the corresponding partial symbol table is mutated into a full |
| 1179 | fledged symbol table by going back and reading the symbols |
| 1180 | for real. |
| 1181 | |
| 1182 | We look for sections with specific names, to tell us what debug |
| 1183 | format to look for: FIXME!!! |
| 1184 | |
| 1185 | elfstab_build_psymtabs() handles STABS symbols; |
| 1186 | mdebug_build_psymtabs() handles ECOFF debugging information. |
| 1187 | |
| 1188 | Note that ELF files have a "minimal" symbol table, which looks a lot |
| 1189 | like a COFF symbol table, but has only the minimal information necessary |
| 1190 | for linking. We process this also, and use the information to |
| 1191 | build gdb's minimal symbol table. This gives us some minimal debugging |
| 1192 | capability even for files compiled without -g. */ |
| 1193 | |
| 1194 | static void |
| 1195 | elf_symfile_read (struct objfile *objfile, symfile_add_flags symfile_flags) |
| 1196 | { |
| 1197 | bfd *abfd = objfile->obfd; |
| 1198 | struct elfinfo ei; |
| 1199 | |
| 1200 | memset ((char *) &ei, 0, sizeof (ei)); |
| 1201 | if (!(objfile->flags & OBJF_READNEVER)) |
| 1202 | bfd_map_over_sections (abfd, elf_locate_sections, (void *) & ei); |
| 1203 | |
| 1204 | elf_read_minimal_symbols (objfile, symfile_flags, &ei); |
| 1205 | |
| 1206 | /* ELF debugging information is inserted into the psymtab in the |
| 1207 | order of least informative first - most informative last. Since |
| 1208 | the psymtab table is searched `most recent insertion first' this |
| 1209 | increases the probability that more detailed debug information |
| 1210 | for a section is found. |
| 1211 | |
| 1212 | For instance, an object file might contain both .mdebug (XCOFF) |
| 1213 | and .debug_info (DWARF2) sections then .mdebug is inserted first |
| 1214 | (searched last) and DWARF2 is inserted last (searched first). If |
| 1215 | we don't do this then the XCOFF info is found first - for code in |
| 1216 | an included file XCOFF info is useless. */ |
| 1217 | |
| 1218 | if (ei.mdebugsect) |
| 1219 | { |
| 1220 | const struct ecoff_debug_swap *swap; |
| 1221 | |
| 1222 | /* .mdebug section, presumably holding ECOFF debugging |
| 1223 | information. */ |
| 1224 | swap = get_elf_backend_data (abfd)->elf_backend_ecoff_debug_swap; |
| 1225 | if (swap) |
| 1226 | elfmdebug_build_psymtabs (objfile, swap, ei.mdebugsect); |
| 1227 | } |
| 1228 | if (ei.stabsect) |
| 1229 | { |
| 1230 | asection *str_sect; |
| 1231 | |
| 1232 | /* Stab sections have an associated string table that looks like |
| 1233 | a separate section. */ |
| 1234 | str_sect = bfd_get_section_by_name (abfd, ".stabstr"); |
| 1235 | |
| 1236 | /* FIXME should probably warn about a stab section without a stabstr. */ |
| 1237 | if (str_sect) |
| 1238 | elfstab_build_psymtabs (objfile, |
| 1239 | ei.stabsect, |
| 1240 | str_sect->filepos, |
| 1241 | bfd_section_size (abfd, str_sect)); |
| 1242 | } |
| 1243 | |
| 1244 | if (dwarf2_has_info (objfile, NULL)) |
| 1245 | { |
| 1246 | dw_index_kind index_kind; |
| 1247 | |
| 1248 | /* elf_sym_fns_gdb_index cannot handle simultaneous non-DWARF |
| 1249 | debug information present in OBJFILE. If there is such debug |
| 1250 | info present never use an index. */ |
| 1251 | if (!objfile_has_partial_symbols (objfile) |
| 1252 | && dwarf2_initialize_objfile (objfile, &index_kind)) |
| 1253 | { |
| 1254 | switch (index_kind) |
| 1255 | { |
| 1256 | case dw_index_kind::GDB_INDEX: |
| 1257 | objfile_set_sym_fns (objfile, &elf_sym_fns_gdb_index); |
| 1258 | break; |
| 1259 | case dw_index_kind::DEBUG_NAMES: |
| 1260 | objfile_set_sym_fns (objfile, &elf_sym_fns_debug_names); |
| 1261 | break; |
| 1262 | } |
| 1263 | } |
| 1264 | else |
| 1265 | { |
| 1266 | /* It is ok to do this even if the stabs reader made some |
| 1267 | partial symbols, because OBJF_PSYMTABS_READ has not been |
| 1268 | set, and so our lazy reader function will still be called |
| 1269 | when needed. */ |
| 1270 | objfile_set_sym_fns (objfile, &elf_sym_fns_lazy_psyms); |
| 1271 | } |
| 1272 | } |
| 1273 | /* If the file has its own symbol tables it has no separate debug |
| 1274 | info. `.dynsym'/`.symtab' go to MSYMBOLS, `.debug_info' goes to |
| 1275 | SYMTABS/PSYMTABS. `.gnu_debuglink' may no longer be present with |
| 1276 | `.note.gnu.build-id'. |
| 1277 | |
| 1278 | .gnu_debugdata is !objfile_has_partial_symbols because it contains only |
| 1279 | .symtab, not .debug_* section. But if we already added .gnu_debugdata as |
| 1280 | an objfile via find_separate_debug_file_in_section there was no separate |
| 1281 | debug info available. Therefore do not attempt to search for another one, |
| 1282 | objfile->separate_debug_objfile->separate_debug_objfile GDB guarantees to |
| 1283 | be NULL and we would possibly violate it. */ |
| 1284 | |
| 1285 | else if (!objfile_has_partial_symbols (objfile) |
| 1286 | && objfile->separate_debug_objfile == NULL |
| 1287 | && objfile->separate_debug_objfile_backlink == NULL) |
| 1288 | { |
| 1289 | std::string debugfile = find_separate_debug_file_by_buildid (objfile); |
| 1290 | |
| 1291 | if (debugfile.empty ()) |
| 1292 | debugfile = find_separate_debug_file_by_debuglink (objfile); |
| 1293 | |
| 1294 | if (!debugfile.empty ()) |
| 1295 | { |
| 1296 | gdb_bfd_ref_ptr debug_bfd (symfile_bfd_open (debugfile.c_str ())); |
| 1297 | |
| 1298 | symbol_file_add_separate (debug_bfd.get (), debugfile.c_str (), |
| 1299 | symfile_flags, objfile); |
| 1300 | } |
| 1301 | } |
| 1302 | } |
| 1303 | |
| 1304 | /* Callback to lazily read psymtabs. */ |
| 1305 | |
| 1306 | static void |
| 1307 | read_psyms (struct objfile *objfile) |
| 1308 | { |
| 1309 | if (dwarf2_has_info (objfile, NULL)) |
| 1310 | dwarf2_build_psymtabs (objfile); |
| 1311 | } |
| 1312 | |
| 1313 | /* Initialize anything that needs initializing when a completely new symbol |
| 1314 | file is specified (not just adding some symbols from another file, e.g. a |
| 1315 | shared library). |
| 1316 | |
| 1317 | We reinitialize buildsym, since we may be reading stabs from an ELF |
| 1318 | file. */ |
| 1319 | |
| 1320 | static void |
| 1321 | elf_new_init (struct objfile *ignore) |
| 1322 | { |
| 1323 | stabsread_new_init (); |
| 1324 | } |
| 1325 | |
| 1326 | /* Perform any local cleanups required when we are done with a particular |
| 1327 | objfile. I.E, we are in the process of discarding all symbol information |
| 1328 | for an objfile, freeing up all memory held for it, and unlinking the |
| 1329 | objfile struct from the global list of known objfiles. */ |
| 1330 | |
| 1331 | static void |
| 1332 | elf_symfile_finish (struct objfile *objfile) |
| 1333 | { |
| 1334 | } |
| 1335 | |
| 1336 | /* ELF specific initialization routine for reading symbols. */ |
| 1337 | |
| 1338 | static void |
| 1339 | elf_symfile_init (struct objfile *objfile) |
| 1340 | { |
| 1341 | /* ELF objects may be reordered, so set OBJF_REORDERED. If we |
| 1342 | find this causes a significant slowdown in gdb then we could |
| 1343 | set it in the debug symbol readers only when necessary. */ |
| 1344 | objfile->flags |= OBJF_REORDERED; |
| 1345 | } |
| 1346 | |
| 1347 | /* Implementation of `sym_get_probes', as documented in symfile.h. */ |
| 1348 | |
| 1349 | static const std::vector<probe *> & |
| 1350 | elf_get_probes (struct objfile *objfile) |
| 1351 | { |
| 1352 | std::vector<probe *> *probes_per_bfd; |
| 1353 | |
| 1354 | /* Have we parsed this objfile's probes already? */ |
| 1355 | probes_per_bfd = (std::vector<probe *> *) bfd_data (objfile->obfd, probe_key); |
| 1356 | |
| 1357 | if (probes_per_bfd == NULL) |
| 1358 | { |
| 1359 | probes_per_bfd = new std::vector<probe *>; |
| 1360 | |
| 1361 | /* Here we try to gather information about all types of probes from the |
| 1362 | objfile. */ |
| 1363 | for (const static_probe_ops *ops : all_static_probe_ops) |
| 1364 | ops->get_probes (probes_per_bfd, objfile); |
| 1365 | |
| 1366 | set_bfd_data (objfile->obfd, probe_key, probes_per_bfd); |
| 1367 | } |
| 1368 | |
| 1369 | return *probes_per_bfd; |
| 1370 | } |
| 1371 | |
| 1372 | /* Helper function used to free the space allocated for storing SystemTap |
| 1373 | probe information. */ |
| 1374 | |
| 1375 | static void |
| 1376 | probe_key_free (bfd *abfd, void *d) |
| 1377 | { |
| 1378 | std::vector<probe *> *probes = (std::vector<probe *> *) d; |
| 1379 | |
| 1380 | for (probe *p : *probes) |
| 1381 | delete p; |
| 1382 | |
| 1383 | delete probes; |
| 1384 | } |
| 1385 | |
| 1386 | \f |
| 1387 | |
| 1388 | /* Implementation `sym_probe_fns', as documented in symfile.h. */ |
| 1389 | |
| 1390 | static const struct sym_probe_fns elf_probe_fns = |
| 1391 | { |
| 1392 | elf_get_probes, /* sym_get_probes */ |
| 1393 | }; |
| 1394 | |
| 1395 | /* Register that we are able to handle ELF object file formats. */ |
| 1396 | |
| 1397 | static const struct sym_fns elf_sym_fns = |
| 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 | NULL, /* 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 lazily reads |
| 1413 | psymbols. */ |
| 1414 | |
| 1415 | const struct sym_fns elf_sym_fns_lazy_psyms = |
| 1416 | { |
| 1417 | elf_new_init, /* init anything gbl to entire symtab */ |
| 1418 | elf_symfile_init, /* read initial info, setup for sym_read() */ |
| 1419 | elf_symfile_read, /* read a symbol file into symtab */ |
| 1420 | read_psyms, /* sym_read_psymbols */ |
| 1421 | elf_symfile_finish, /* finished with file, cleanup */ |
| 1422 | default_symfile_offsets, /* Translate ext. to int. relocation */ |
| 1423 | elf_symfile_segments, /* Get segment information from a file. */ |
| 1424 | NULL, |
| 1425 | default_symfile_relocate, /* Relocate a debug section. */ |
| 1426 | &elf_probe_fns, /* sym_probe_fns */ |
| 1427 | &psym_functions |
| 1428 | }; |
| 1429 | |
| 1430 | /* The same as elf_sym_fns, but not registered and uses the |
| 1431 | DWARF-specific GNU index rather than psymtab. */ |
| 1432 | const struct sym_fns elf_sym_fns_gdb_index = |
| 1433 | { |
| 1434 | elf_new_init, /* init anything gbl to entire symab */ |
| 1435 | elf_symfile_init, /* read initial info, setup for sym_red() */ |
| 1436 | elf_symfile_read, /* read a symbol file into symtab */ |
| 1437 | NULL, /* sym_read_psymbols */ |
| 1438 | elf_symfile_finish, /* finished with file, cleanup */ |
| 1439 | default_symfile_offsets, /* Translate ext. to int. relocatin */ |
| 1440 | elf_symfile_segments, /* Get segment information from a file. */ |
| 1441 | NULL, |
| 1442 | default_symfile_relocate, /* Relocate a debug section. */ |
| 1443 | &elf_probe_fns, /* sym_probe_fns */ |
| 1444 | &dwarf2_gdb_index_functions |
| 1445 | }; |
| 1446 | |
| 1447 | /* The same as elf_sym_fns, but not registered and uses the |
| 1448 | DWARF-specific .debug_names index rather than psymtab. */ |
| 1449 | const struct sym_fns elf_sym_fns_debug_names = |
| 1450 | { |
| 1451 | elf_new_init, /* init anything gbl to entire symab */ |
| 1452 | elf_symfile_init, /* read initial info, setup for sym_red() */ |
| 1453 | elf_symfile_read, /* read a symbol file into symtab */ |
| 1454 | NULL, /* sym_read_psymbols */ |
| 1455 | elf_symfile_finish, /* finished with file, cleanup */ |
| 1456 | default_symfile_offsets, /* Translate ext. to int. relocatin */ |
| 1457 | elf_symfile_segments, /* Get segment information from a file. */ |
| 1458 | NULL, |
| 1459 | default_symfile_relocate, /* Relocate a debug section. */ |
| 1460 | &elf_probe_fns, /* sym_probe_fns */ |
| 1461 | &dwarf2_debug_names_functions |
| 1462 | }; |
| 1463 | |
| 1464 | /* STT_GNU_IFUNC resolver vector to be installed to gnu_ifunc_fns_p. */ |
| 1465 | |
| 1466 | static const struct gnu_ifunc_fns elf_gnu_ifunc_fns = |
| 1467 | { |
| 1468 | elf_gnu_ifunc_resolve_addr, |
| 1469 | elf_gnu_ifunc_resolve_name, |
| 1470 | elf_gnu_ifunc_resolver_stop, |
| 1471 | elf_gnu_ifunc_resolver_return_stop |
| 1472 | }; |
| 1473 | |
| 1474 | void |
| 1475 | _initialize_elfread (void) |
| 1476 | { |
| 1477 | probe_key = register_bfd_data_with_cleanup (NULL, probe_key_free); |
| 1478 | add_symtab_fns (bfd_target_elf_flavour, &elf_sym_fns); |
| 1479 | |
| 1480 | elf_objfile_gnu_ifunc_cache_data = register_objfile_data (); |
| 1481 | gnu_ifunc_fns_p = &elf_gnu_ifunc_fns; |
| 1482 | } |