1 /* OS ABI variant handling for GDB. 2 3 Copyright (C) 2001, 2002, 2003, 2004, 2007, 2008, 2009 4 Free Software Foundation, Inc. 5 6 This file is part of GDB. 7 8 This program is free software; you can redistribute it and/or modify 9 it under the terms of the GNU General Public License as published by 10 the Free Software Foundation; either version 3 of the License, or 11 (at your option) any later version. 12 13 This program is distributed in the hope that it will be useful, 14 but WITHOUT ANY WARRANTY; without even the implied warranty of 15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 16 GNU General Public License for more details. 17 18 You should have received a copy of the GNU General Public License 19 along with this program. If not, see <http://www.gnu.org/licenses/>. */ 20 21 #include "defs.h" 22 23 #include "gdb_assert.h" 24 #include "gdb_string.h" 25 26 #include "osabi.h" 27 #include "arch-utils.h" 28 #include "gdbcmd.h" 29 #include "command.h" 30 31 #include "elf-bfd.h" 32 33 #ifndef GDB_OSABI_DEFAULT 34 #define GDB_OSABI_DEFAULT GDB_OSABI_UNKNOWN 35 #endif 36 37 /* State for the "set osabi" command. */ 38 static enum { osabi_auto, osabi_default, osabi_user } user_osabi_state; 39 static enum gdb_osabi user_selected_osabi; 40 static const char *gdb_osabi_available_names[GDB_OSABI_INVALID + 3] = { 41 "auto", 42 "default", 43 "none", 44 NULL 45 }; 46 static const char *set_osabi_string; 47 48 /* This table matches the indices assigned to enum gdb_osabi. Keep 49 them in sync. */ 50 static const char * const gdb_osabi_names[] = 51 { 52 "none", 53 54 "SVR4", 55 "GNU/Hurd", 56 "Solaris", 57 "OSF/1", 58 "GNU/Linux", 59 "FreeBSD a.out", 60 "FreeBSD ELF", 61 "NetBSD a.out", 62 "NetBSD ELF", 63 "OpenBSD ELF", 64 "DragonFly", 65 "Windows CE", 66 "DJGPP", 67 "Irix", 68 "Interix", 69 "HP/UX ELF", 70 "HP/UX SOM", 71 72 "QNX Neutrino", 73 74 "Cygwin", 75 "AIX", 76 "DICOS", 77 "Darwin", 78 79 "<invalid>" 80 }; 81 82 const char * 83 gdbarch_osabi_name (enum gdb_osabi osabi) 84 { 85 if (osabi >= GDB_OSABI_UNKNOWN && osabi < GDB_OSABI_INVALID) 86 return gdb_osabi_names[osabi]; 87 88 return gdb_osabi_names[GDB_OSABI_INVALID]; 89 } 90 91 /* Lookup the OS ABI corresponding to the specified target description 92 string. */ 93 94 enum gdb_osabi 95 osabi_from_tdesc_string (const char *name) 96 { 97 int i; 98 99 for (i = 0; i < ARRAY_SIZE (gdb_osabi_names); i++) 100 if (strcmp (name, gdb_osabi_names[i]) == 0) 101 { 102 /* See note above: the name table matches the indices assigned 103 to enum gdb_osabi. */ 104 enum gdb_osabi osabi = (enum gdb_osabi) i; 105 106 if (osabi == GDB_OSABI_INVALID) 107 return GDB_OSABI_UNKNOWN; 108 else 109 return osabi; 110 } 111 112 return GDB_OSABI_UNKNOWN; 113 } 114 115 /* Handler for a given architecture/OS ABI pair. There should be only 116 one handler for a given OS ABI each architecture family. */ 117 struct gdb_osabi_handler 118 { 119 struct gdb_osabi_handler *next; 120 const struct bfd_arch_info *arch_info; 121 enum gdb_osabi osabi; 122 void (*init_osabi)(struct gdbarch_info, struct gdbarch *); 123 }; 124 125 static struct gdb_osabi_handler *gdb_osabi_handler_list; 126 127 void 128 gdbarch_register_osabi (enum bfd_architecture arch, unsigned long machine, 129 enum gdb_osabi osabi, 130 void (*init_osabi)(struct gdbarch_info, 131 struct gdbarch *)) 132 { 133 struct gdb_osabi_handler **handler_p; 134 const struct bfd_arch_info *arch_info = bfd_lookup_arch (arch, machine); 135 const char **name_ptr; 136 137 /* Registering an OS ABI handler for "unknown" is not allowed. */ 138 if (osabi == GDB_OSABI_UNKNOWN) 139 { 140 internal_error 141 (__FILE__, __LINE__, 142 _("gdbarch_register_osabi: An attempt to register a handler for " 143 "OS ABI \"%s\" for architecture %s was made. The handler will " 144 "not be registered"), 145 gdbarch_osabi_name (osabi), 146 bfd_printable_arch_mach (arch, machine)); 147 return; 148 } 149 150 gdb_assert (arch_info); 151 152 for (handler_p = &gdb_osabi_handler_list; *handler_p != NULL; 153 handler_p = &(*handler_p)->next) 154 { 155 if ((*handler_p)->arch_info == arch_info 156 && (*handler_p)->osabi == osabi) 157 { 158 internal_error 159 (__FILE__, __LINE__, 160 _("gdbarch_register_osabi: A handler for OS ABI \"%s\" " 161 "has already been registered for architecture %s"), 162 gdbarch_osabi_name (osabi), 163 arch_info->printable_name); 164 /* If user wants to continue, override previous definition. */ 165 (*handler_p)->init_osabi = init_osabi; 166 return; 167 } 168 } 169 170 (*handler_p) 171 = (struct gdb_osabi_handler *) xmalloc (sizeof (struct gdb_osabi_handler)); 172 (*handler_p)->next = NULL; 173 (*handler_p)->arch_info = arch_info; 174 (*handler_p)->osabi = osabi; 175 (*handler_p)->init_osabi = init_osabi; 176 177 /* Add this OS ABI to the list of enum values for "set osabi", if it isn't 178 already there. */ 179 for (name_ptr = gdb_osabi_available_names; *name_ptr; name_ptr ++) 180 { 181 if (*name_ptr == gdbarch_osabi_name (osabi)) 182 return; 183 } 184 *name_ptr++ = gdbarch_osabi_name (osabi); 185 *name_ptr = NULL; 186 } 187 188 189 /* Sniffer to find the OS ABI for a given file's architecture and flavour. 190 It is legal to have multiple sniffers for each arch/flavour pair, to 191 disambiguate one OS's a.out from another, for example. The first sniffer 192 to return something other than GDB_OSABI_UNKNOWN wins, so a sniffer should 193 be careful to claim a file only if it knows for sure what it is. */ 194 struct gdb_osabi_sniffer 195 { 196 struct gdb_osabi_sniffer *next; 197 enum bfd_architecture arch; /* bfd_arch_unknown == wildcard */ 198 enum bfd_flavour flavour; 199 enum gdb_osabi (*sniffer)(bfd *); 200 }; 201 202 static struct gdb_osabi_sniffer *gdb_osabi_sniffer_list; 203 204 void 205 gdbarch_register_osabi_sniffer (enum bfd_architecture arch, 206 enum bfd_flavour flavour, 207 enum gdb_osabi (*sniffer_fn)(bfd *)) 208 { 209 struct gdb_osabi_sniffer *sniffer; 210 211 sniffer = 212 (struct gdb_osabi_sniffer *) xmalloc (sizeof (struct gdb_osabi_sniffer)); 213 sniffer->arch = arch; 214 sniffer->flavour = flavour; 215 sniffer->sniffer = sniffer_fn; 216 217 sniffer->next = gdb_osabi_sniffer_list; 218 gdb_osabi_sniffer_list = sniffer; 219 } 220 221 222 enum gdb_osabi 223 gdbarch_lookup_osabi (bfd *abfd) 224 { 225 struct gdb_osabi_sniffer *sniffer; 226 enum gdb_osabi osabi, match; 227 int match_specific; 228 229 /* If we aren't in "auto" mode, return the specified OS ABI. */ 230 if (user_osabi_state == osabi_user) 231 return user_selected_osabi; 232 233 /* If we don't have a binary, just return unknown. The caller may 234 have other sources the OSABI can be extracted from, e.g., the 235 target description. */ 236 if (abfd == NULL) 237 return GDB_OSABI_UNKNOWN; 238 239 match = GDB_OSABI_UNKNOWN; 240 match_specific = 0; 241 242 for (sniffer = gdb_osabi_sniffer_list; sniffer != NULL; 243 sniffer = sniffer->next) 244 { 245 if ((sniffer->arch == bfd_arch_unknown /* wildcard */ 246 || sniffer->arch == bfd_get_arch (abfd)) 247 && sniffer->flavour == bfd_get_flavour (abfd)) 248 { 249 osabi = (*sniffer->sniffer) (abfd); 250 if (osabi < GDB_OSABI_UNKNOWN || osabi >= GDB_OSABI_INVALID) 251 { 252 internal_error 253 (__FILE__, __LINE__, 254 _("gdbarch_lookup_osabi: invalid OS ABI (%d) from sniffer " 255 "for architecture %s flavour %d"), 256 (int) osabi, 257 bfd_printable_arch_mach (bfd_get_arch (abfd), 0), 258 (int) bfd_get_flavour (abfd)); 259 } 260 else if (osabi != GDB_OSABI_UNKNOWN) 261 { 262 /* A specific sniffer always overrides a generic sniffer. 263 Croak on multiple match if the two matches are of the 264 same class. If the user wishes to continue, we'll use 265 the first match. */ 266 if (match != GDB_OSABI_UNKNOWN) 267 { 268 if ((match_specific && sniffer->arch != bfd_arch_unknown) 269 || (!match_specific && sniffer->arch == bfd_arch_unknown)) 270 { 271 internal_error 272 (__FILE__, __LINE__, 273 _("gdbarch_lookup_osabi: multiple %sspecific OS ABI " 274 "match for architecture %s flavour %d: first " 275 "match \"%s\", second match \"%s\""), 276 match_specific ? "" : "non-", 277 bfd_printable_arch_mach (bfd_get_arch (abfd), 0), 278 (int) bfd_get_flavour (abfd), 279 gdbarch_osabi_name (match), 280 gdbarch_osabi_name (osabi)); 281 } 282 else if (sniffer->arch != bfd_arch_unknown) 283 { 284 match = osabi; 285 match_specific = 1; 286 } 287 } 288 else 289 { 290 match = osabi; 291 if (sniffer->arch != bfd_arch_unknown) 292 match_specific = 1; 293 } 294 } 295 } 296 } 297 298 return match; 299 } 300 301 302 /* Return non-zero if architecture A can run code written for 303 architecture B. */ 304 static int 305 can_run_code_for (const struct bfd_arch_info *a, const struct bfd_arch_info *b) 306 { 307 /* BFD's 'A->compatible (A, B)' functions return zero if A and B are 308 incompatible. But if they are compatible, it returns the 'more 309 featureful' of the two arches. That is, if A can run code 310 written for B, but B can't run code written for A, then it'll 311 return A. 312 313 struct bfd_arch_info objects are singletons: that is, there's 314 supposed to be exactly one instance for a given machine. So you 315 can tell whether two are equivalent by comparing pointers. */ 316 return (a == b || a->compatible (a, b) == a); 317 } 318 319 320 void 321 gdbarch_init_osabi (struct gdbarch_info info, struct gdbarch *gdbarch) 322 { 323 struct gdb_osabi_handler *handler; 324 325 if (info.osabi == GDB_OSABI_UNKNOWN) 326 { 327 /* Don't complain about an unknown OSABI. Assume the user knows 328 what they are doing. */ 329 return; 330 } 331 332 for (handler = gdb_osabi_handler_list; handler != NULL; 333 handler = handler->next) 334 { 335 if (handler->osabi != info.osabi) 336 continue; 337 338 /* If the architecture described by ARCH_INFO can run code for 339 the architcture we registered the handler for, then the 340 handler is applicable. Note, though, that if the handler is 341 for an architecture that is a superset of ARCH_INFO, we can't 342 use that --- it would be perfectly correct for it to install 343 gdbarch methods that refer to registers / instructions / 344 other facilities ARCH_INFO doesn't have. 345 346 NOTE: kettenis/20021027: There may be more than one machine 347 type that is compatible with the desired machine type. Right 348 now we simply return the first match, which is fine for now. 349 However, we might want to do something smarter in the future. */ 350 /* NOTE: cagney/2003-10-23: The code for "a can_run_code_for b" 351 is implemented using BFD's compatible method (a->compatible 352 (b) == a -- the lowest common denominator between a and b is 353 a). That method's definition of compatible may not be as you 354 expect. For instance the test "amd64 can run code for i386" 355 (or more generally "64-bit ISA can run code for the 32-bit 356 ISA"). BFD doesn't normally consider 32-bit and 64-bit 357 "compatible" so it doesn't succeed. */ 358 if (can_run_code_for (info.bfd_arch_info, handler->arch_info)) 359 { 360 (*handler->init_osabi) (info, gdbarch); 361 return; 362 } 363 } 364 365 warning 366 ("A handler for the OS ABI \"%s\" is not built into this configuration\n" 367 "of GDB. Attempting to continue with the default %s settings.\n", 368 gdbarch_osabi_name (info.osabi), 369 info.bfd_arch_info->printable_name); 370 } 371 372 /* Limit on the amount of data to be read. */ 373 #define MAX_NOTESZ 128 374 375 /* Return non-zero if NOTE matches NAME, DESCSZ and TYPE. */ 376 377 static int 378 check_note (bfd *abfd, asection *sect, const char *note, 379 const char *name, unsigned long descsz, unsigned long type) 380 { 381 unsigned long notesz; 382 383 /* Calculate the size of this note. */ 384 notesz = strlen (name) + 1; 385 notesz = ((notesz + 3) & ~3); 386 notesz += descsz; 387 notesz = ((notesz + 3) & ~3); 388 389 /* If this assertion triggers, increase MAX_NOTESZ. */ 390 gdb_assert (notesz <= MAX_NOTESZ); 391 392 /* Check whether SECT is big enough to comtain the complete note. */ 393 if (notesz > bfd_section_size (abfd, sect)) 394 return 0; 395 396 /* Check the note name. */ 397 if (bfd_h_get_32 (abfd, note) != (strlen (name) + 1) 398 || strcmp (note + 12, name) != 0) 399 return 0; 400 401 /* Check the descriptor size. */ 402 if (bfd_h_get_32 (abfd, note + 4) != descsz) 403 return 0; 404 405 /* Check the note type. */ 406 if (bfd_h_get_32 (abfd, note + 8) != type) 407 return 0; 408 409 return 1; 410 } 411 412 /* Generic sniffer for ELF flavoured files. */ 413 414 void 415 generic_elf_osabi_sniff_abi_tag_sections (bfd *abfd, asection *sect, void *obj) 416 { 417 enum gdb_osabi *osabi = obj; 418 const char *name; 419 unsigned int sectsize; 420 char *note; 421 422 name = bfd_get_section_name (abfd, sect); 423 sectsize = bfd_section_size (abfd, sect); 424 425 /* Limit the amount of data to read. */ 426 if (sectsize > MAX_NOTESZ) 427 sectsize = MAX_NOTESZ; 428 429 note = alloca (sectsize); 430 bfd_get_section_contents (abfd, sect, note, 0, sectsize); 431 432 /* .note.ABI-tag notes, used by GNU/Linux and FreeBSD. */ 433 if (strcmp (name, ".note.ABI-tag") == 0) 434 { 435 /* GNU. */ 436 if (check_note (abfd, sect, note, "GNU", 16, NT_GNU_ABI_TAG)) 437 { 438 unsigned int abi_tag = bfd_h_get_32 (abfd, note + 16); 439 440 switch (abi_tag) 441 { 442 case GNU_ABI_TAG_LINUX: 443 *osabi = GDB_OSABI_LINUX; 444 break; 445 446 case GNU_ABI_TAG_HURD: 447 *osabi = GDB_OSABI_HURD; 448 break; 449 450 case GNU_ABI_TAG_SOLARIS: 451 *osabi = GDB_OSABI_SOLARIS; 452 break; 453 454 case GNU_ABI_TAG_FREEBSD: 455 *osabi = GDB_OSABI_FREEBSD_ELF; 456 break; 457 458 case GNU_ABI_TAG_NETBSD: 459 *osabi = GDB_OSABI_NETBSD_ELF; 460 break; 461 462 default: 463 internal_error (__FILE__, __LINE__, _("\ 464 generic_elf_osabi_sniff_abi_tag_sections: unknown OS number %d"), 465 abi_tag); 466 } 467 return; 468 } 469 470 /* FreeBSD. */ 471 if (check_note (abfd, sect, note, "FreeBSD", 4, NT_FREEBSD_ABI_TAG)) 472 { 473 /* There is no need to check the version yet. */ 474 *osabi = GDB_OSABI_FREEBSD_ELF; 475 return; 476 } 477 478 /* DragonFly. */ 479 if (check_note (abfd, sect, note, "DragonFly", 4, NT_DRAGONFLY_ABI_TAG)) 480 { 481 /* There is no need to check the version yet. */ 482 *osabi = GDB_OSABI_DRAGONFLY; 483 return; 484 } 485 486 return; 487 } 488 489 /* .note.netbsd.ident notes, used by NetBSD. */ 490 if (strcmp (name, ".note.netbsd.ident") == 0 491 && check_note (abfd, sect, note, "NetBSD", 4, NT_NETBSD_IDENT)) 492 { 493 /* There is no need to check the version yet. */ 494 *osabi = GDB_OSABI_NETBSD_ELF; 495 return; 496 } 497 498 /* .note.openbsd.ident notes, used by OpenBSD. */ 499 if (strcmp (name, ".note.openbsd.ident") == 0 500 && check_note (abfd, sect, note, "OpenBSD", 4, NT_OPENBSD_IDENT)) 501 { 502 /* There is no need to check the version yet. */ 503 *osabi = GDB_OSABI_OPENBSD_ELF; 504 return; 505 } 506 507 /* .note.netbsdcore.procinfo notes, used by NetBSD. */ 508 if (strcmp (name, ".note.netbsdcore.procinfo") == 0) 509 { 510 *osabi = GDB_OSABI_NETBSD_ELF; 511 return; 512 } 513 } 514 515 static enum gdb_osabi 516 generic_elf_osabi_sniffer (bfd *abfd) 517 { 518 unsigned int elfosabi; 519 enum gdb_osabi osabi = GDB_OSABI_UNKNOWN; 520 521 elfosabi = elf_elfheader (abfd)->e_ident[EI_OSABI]; 522 523 switch (elfosabi) 524 { 525 case ELFOSABI_NONE: 526 /* When the EI_OSABI field in the ELF header is ELFOSABI_NONE 527 (0), then the ELF structures in the file are conforming to 528 the base specification for that machine (there are no 529 OS-specific extensions). In order to determine the real OS 530 in use we must look for OS-specific notes. */ 531 bfd_map_over_sections (abfd, 532 generic_elf_osabi_sniff_abi_tag_sections, 533 &osabi); 534 break; 535 536 case ELFOSABI_FREEBSD: 537 osabi = GDB_OSABI_FREEBSD_ELF; 538 break; 539 540 case ELFOSABI_NETBSD: 541 osabi = GDB_OSABI_NETBSD_ELF; 542 break; 543 544 case ELFOSABI_LINUX: 545 osabi = GDB_OSABI_LINUX; 546 break; 547 548 case ELFOSABI_HURD: 549 osabi = GDB_OSABI_HURD; 550 break; 551 552 case ELFOSABI_SOLARIS: 553 osabi = GDB_OSABI_SOLARIS; 554 break; 555 556 case ELFOSABI_HPUX: 557 /* For some reason the default value for the EI_OSABI field is 558 ELFOSABI_HPUX for all PA-RISC targets (with the exception of 559 GNU/Linux). We use HP-UX ELF as the default, but let any 560 OS-specific notes override this. */ 561 osabi = GDB_OSABI_HPUX_ELF; 562 bfd_map_over_sections (abfd, 563 generic_elf_osabi_sniff_abi_tag_sections, 564 &osabi); 565 break; 566 } 567 568 if (osabi == GDB_OSABI_UNKNOWN) 569 { 570 /* The FreeBSD folks have been naughty; they stored the string 571 "FreeBSD" in the padding of the e_ident field of the ELF 572 header to "brand" their ELF binaries in FreeBSD 3.x. */ 573 if (memcmp (&elf_elfheader (abfd)->e_ident[8], 574 "FreeBSD", sizeof ("FreeBSD")) == 0) 575 osabi = GDB_OSABI_FREEBSD_ELF; 576 } 577 578 return osabi; 579 } 580 581 static void 582 set_osabi (char *args, int from_tty, struct cmd_list_element *c) 583 { 584 struct gdbarch_info info; 585 586 if (strcmp (set_osabi_string, "auto") == 0) 587 user_osabi_state = osabi_auto; 588 else if (strcmp (set_osabi_string, "default") == 0) 589 { 590 user_selected_osabi = GDB_OSABI_DEFAULT; 591 user_osabi_state = osabi_user; 592 } 593 else if (strcmp (set_osabi_string, "none") == 0) 594 { 595 user_selected_osabi = GDB_OSABI_UNKNOWN; 596 user_osabi_state = osabi_user; 597 } 598 else 599 { 600 int i; 601 for (i = 1; i < GDB_OSABI_INVALID; i++) 602 if (strcmp (set_osabi_string, gdbarch_osabi_name (i)) == 0) 603 { 604 user_selected_osabi = i; 605 user_osabi_state = osabi_user; 606 break; 607 } 608 if (i == GDB_OSABI_INVALID) 609 internal_error (__FILE__, __LINE__, 610 _("Invalid OS ABI \"%s\" passed to command handler."), 611 set_osabi_string); 612 } 613 614 /* NOTE: At some point (true multiple architectures) we'll need to be more 615 graceful here. */ 616 gdbarch_info_init (&info); 617 if (! gdbarch_update_p (info)) 618 internal_error (__FILE__, __LINE__, _("Updating OS ABI failed.")); 619 } 620 621 static void 622 show_osabi (struct ui_file *file, int from_tty, struct cmd_list_element *c, 623 const char *value) 624 { 625 if (user_osabi_state == osabi_auto) 626 fprintf_filtered (file, 627 _("The current OS ABI is \"auto\" (currently \"%s\").\n"), 628 gdbarch_osabi_name (gdbarch_osabi (get_current_arch ()))); 629 else 630 fprintf_filtered (file, _("The current OS ABI is \"%s\".\n"), 631 gdbarch_osabi_name (user_selected_osabi)); 632 633 if (GDB_OSABI_DEFAULT != GDB_OSABI_UNKNOWN) 634 fprintf_filtered (file, _("The default OS ABI is \"%s\".\n"), 635 gdbarch_osabi_name (GDB_OSABI_DEFAULT)); 636 } 637 638 extern initialize_file_ftype _initialize_gdb_osabi; /* -Wmissing-prototype */ 639 640 void 641 _initialize_gdb_osabi (void) 642 { 643 struct cmd_list_element *c; 644 645 if (strcmp (gdb_osabi_names[GDB_OSABI_INVALID], "<invalid>") != 0) 646 internal_error 647 (__FILE__, __LINE__, 648 _("_initialize_gdb_osabi: gdb_osabi_names[] is inconsistent")); 649 650 /* Register a generic sniffer for ELF flavoured files. */ 651 gdbarch_register_osabi_sniffer (bfd_arch_unknown, 652 bfd_target_elf_flavour, 653 generic_elf_osabi_sniffer); 654 655 /* Register the "set osabi" command. */ 656 add_setshow_enum_cmd ("osabi", class_support, gdb_osabi_available_names, 657 &set_osabi_string, _("\ 658 Set OS ABI of target."), _("\ 659 Show OS ABI of target."), NULL, 660 set_osabi, 661 show_osabi, 662 &setlist, &showlist); 663 user_osabi_state = osabi_auto; 664 } 665