gdb/osabi.c

   1 /* OS ABI variant handling for GDB.
   2    Copyright 2001, 2002, 2003 Free Software Foundation, Inc.
   3
   4    This file is part of GDB.
   5
   6    This program is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 2 of the License, or
   9    (at your option) any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program; if not, write to the Free Software
  18    Foundation, Inc., 59 Temple Place - Suite 330,
  19    Boston, MA 02111-1307, USA.  */
  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   "Windows CE",
  64   "DJGPP",
  65   "NetWare",
  66   "Irix",
  67   "LynxOS",
  68   "Interix",
  69   "HP/UX ELF",
  70   "HP/UX SOM",
  71
  72   "ARM EABI v1",
  73   "ARM EABI v2",
  74   "ARM APCS",
  75   "QNX Neutrino",
  76
  77   "Cygwin",
  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 /* Handler for a given architecture/OS ABI pair.  There should be only
  92    one handler for a given OS ABI each architecture family.  */
  93 struct gdb_osabi_handler
  94 {
  95   struct gdb_osabi_handler *next;
  96   const struct bfd_arch_info *arch_info;
  97   enum gdb_osabi osabi;
  98   void (*init_osabi)(struct gdbarch_info, struct gdbarch *);
  99 };
 100
 101 static struct gdb_osabi_handler *gdb_osabi_handler_list;
 102
 103 void
 104 gdbarch_register_osabi (enum bfd_architecture arch, unsigned long machine,
 105                         enum gdb_osabi osabi,
 106                         void (*init_osabi)(struct gdbarch_info,
 107                                            struct gdbarch *))
 108 {
 109   struct gdb_osabi_handler **handler_p;
 110   const struct bfd_arch_info *arch_info = bfd_lookup_arch (arch, machine);
 111   const char **name_ptr;
 112
 113   /* Registering an OS ABI handler for "unknown" is not allowed.  */
 114   if (osabi == GDB_OSABI_UNKNOWN)
 115     {
 116       internal_error
 117         (__FILE__, __LINE__,
 118          "gdbarch_register_osabi: An attempt to register a handler for "
 119          "OS ABI \"%s\" for architecture %s was made.  The handler will "
 120          "not be registered",
 121          gdbarch_osabi_name (osabi),
 122          bfd_printable_arch_mach (arch, machine));
 123       return;
 124     }
 125
 126   gdb_assert (arch_info);
 127
 128   for (handler_p = &gdb_osabi_handler_list; *handler_p != NULL;
 129        handler_p = &(*handler_p)->next)
 130     {
 131       if ((*handler_p)->arch_info == arch_info
 132           && (*handler_p)->osabi == osabi)
 133         {
 134           internal_error
 135             (__FILE__, __LINE__,
 136              "gdbarch_register_osabi: A handler for OS ABI \"%s\" "
 137              "has already been registered for architecture %s",
 138              gdbarch_osabi_name (osabi),
 139              arch_info->printable_name);
 140           /* If user wants to continue, override previous definition.  */
 141           (*handler_p)->init_osabi = init_osabi;
 142           return;
 143         }
 144     }
 145
 146   (*handler_p)
 147     = (struct gdb_osabi_handler *) xmalloc (sizeof (struct gdb_osabi_handler));
 148   (*handler_p)->next = NULL;
 149   (*handler_p)->arch_info = arch_info;
 150   (*handler_p)->osabi = osabi;
 151   (*handler_p)->init_osabi = init_osabi;
 152
 153   /* Add this OS ABI to the list of enum values for "set osabi", if it isn't
 154      already there.  */
 155   for (name_ptr = gdb_osabi_available_names; *name_ptr; name_ptr ++)
 156     {
 157       if (*name_ptr == gdbarch_osabi_name (osabi))
 158         return;
 159     }
 160   *name_ptr++ = gdbarch_osabi_name (osabi);
 161   *name_ptr = NULL;
 162 }
 163 \f
 164
 165 /* Sniffer to find the OS ABI for a given file's architecture and flavour.
 166    It is legal to have multiple sniffers for each arch/flavour pair, to
 167    disambiguate one OS's a.out from another, for example.  The first sniffer
 168    to return something other than GDB_OSABI_UNKNOWN wins, so a sniffer should
 169    be careful to claim a file only if it knows for sure what it is.  */
 170 struct gdb_osabi_sniffer
 171 {
 172   struct gdb_osabi_sniffer *next;
 173   enum bfd_architecture arch;   /* bfd_arch_unknown == wildcard */
 174   enum bfd_flavour flavour;
 175   enum gdb_osabi (*sniffer)(bfd *);
 176 };
 177
 178 static struct gdb_osabi_sniffer *gdb_osabi_sniffer_list;
 179
 180 void
 181 gdbarch_register_osabi_sniffer (enum bfd_architecture arch,
 182                                 enum bfd_flavour flavour,
 183                                 enum gdb_osabi (*sniffer_fn)(bfd *))
 184 {
 185   struct gdb_osabi_sniffer *sniffer;
 186
 187   sniffer =
 188     (struct gdb_osabi_sniffer *) xmalloc (sizeof (struct gdb_osabi_sniffer));
 189   sniffer->arch = arch;
 190   sniffer->flavour = flavour;
 191   sniffer->sniffer = sniffer_fn;
 192
 193   sniffer->next = gdb_osabi_sniffer_list;
 194   gdb_osabi_sniffer_list = sniffer;
 195 }
 196 \f
 197
 198 enum gdb_osabi
 199 gdbarch_lookup_osabi (bfd *abfd)
 200 {
 201   struct gdb_osabi_sniffer *sniffer;
 202   enum gdb_osabi osabi, match;
 203   int match_specific;
 204
 205   /* If we aren't in "auto" mode, return the specified OS ABI.  */
 206   if (user_osabi_state == osabi_user)
 207     return user_selected_osabi;
 208
 209   /* If we don't have a binary, return the default OS ABI (if set) or
 210      an inconclusive result (otherwise).  */
 211   if (abfd == NULL)
 212     {
 213       if (GDB_OSABI_DEFAULT != GDB_OSABI_UNKNOWN)
 214         return GDB_OSABI_DEFAULT;
 215       else
 216         return GDB_OSABI_UNINITIALIZED;
 217     }
 218
 219   match = GDB_OSABI_UNKNOWN;
 220   match_specific = 0;
 221
 222   for (sniffer = gdb_osabi_sniffer_list; sniffer != NULL;
 223        sniffer = sniffer->next)
 224     {
 225       if ((sniffer->arch == bfd_arch_unknown /* wildcard */
 226            || sniffer->arch == bfd_get_arch (abfd))
 227           && sniffer->flavour == bfd_get_flavour (abfd))
 228         {
 229           osabi = (*sniffer->sniffer) (abfd);
 230           if (osabi < GDB_OSABI_UNKNOWN || osabi >= GDB_OSABI_INVALID)
 231             {
 232               internal_error
 233                 (__FILE__, __LINE__,
 234                  "gdbarch_lookup_osabi: invalid OS ABI (%d) from sniffer "
 235                  "for architecture %s flavour %d",
 236                  (int) osabi,
 237                  bfd_printable_arch_mach (bfd_get_arch (abfd), 0),
 238                  (int) bfd_get_flavour (abfd));
 239             }
 240           else if (osabi != GDB_OSABI_UNKNOWN)
 241             {
 242               /* A specific sniffer always overrides a generic sniffer.
 243                  Croak on multiple match if the two matches are of the
 244                  same class.  If the user wishes to continue, we'll use
 245                  the first match.  */
 246               if (match != GDB_OSABI_UNKNOWN)
 247                 {
 248                   if ((match_specific && sniffer->arch != bfd_arch_unknown)
 249                    || (!match_specific && sniffer->arch == bfd_arch_unknown))
 250                     {
 251                       internal_error
 252                         (__FILE__, __LINE__,
 253                          "gdbarch_lookup_osabi: multiple %sspecific OS ABI "
 254                          "match for architecture %s flavour %d: first "
 255                          "match \"%s\", second match \"%s\"",
 256                          match_specific ? "" : "non-",
 257                          bfd_printable_arch_mach (bfd_get_arch (abfd), 0),
 258                          (int) bfd_get_flavour (abfd),
 259                          gdbarch_osabi_name (match),
 260                          gdbarch_osabi_name (osabi));
 261                     }
 262                   else if (sniffer->arch != bfd_arch_unknown)
 263                     {
 264                       match = osabi;
 265                       match_specific = 1;
 266                     }
 267                 }
 268               else
 269                 {
 270                   match = osabi;
 271                   if (sniffer->arch != bfd_arch_unknown)
 272                     match_specific = 1;
 273                 }
 274             }
 275         }
 276     }
 277
 278   /* If we didn't find a match, but a default was specified at configure
 279      time, return the default.  */
 280   if (GDB_OSABI_DEFAULT != GDB_OSABI_UNKNOWN && match == GDB_OSABI_UNKNOWN)
 281     return GDB_OSABI_DEFAULT;
 282   else
 283     return match;
 284 }
 285
 286
 287 /* Return non-zero if architecture A can run code written for
 288    architecture B.  */
 289 static int
 290 can_run_code_for (const struct bfd_arch_info *a, const struct bfd_arch_info *b)
 291 {
 292   /* BFD's 'A->compatible (A, B)' functions return zero if A and B are
 293      incompatible.  But if they are compatible, it returns the 'more
 294      featureful' of the two arches.  That is, if A can run code
 295      written for B, but B can't run code written for A, then it'll
 296      return A.
 297
 298      struct bfd_arch_info objects are atoms: that is, there's supposed
 299      to be exactly one instance for a given machine.  So you can tell
 300      whether two are equivalent by comparing pointers.  */
 301   return (a == b || a->compatible (a, b) == a);
 302 }
 303
 304
 305 void
 306 gdbarch_init_osabi (struct gdbarch_info info, struct gdbarch *gdbarch)
 307 {
 308   const struct bfd_arch_info *arch_info = gdbarch_bfd_arch_info (gdbarch);
 309   struct gdb_osabi_handler *handler;
 310
 311   if (info.osabi == GDB_OSABI_UNKNOWN)
 312     {
 313       /* Don't complain about an unknown OSABI.  Assume the user knows
 314          what they are doing.  */
 315       return;
 316     }
 317
 318   for (handler = gdb_osabi_handler_list; handler != NULL;
 319        handler = handler->next)
 320     {
 321       if (handler->osabi != info.osabi)
 322         continue;
 323
 324       /* If the architecture described by ARCH_INFO can run code for
 325          the architcture we registered the handler for, then the
 326          handler is applicable.  Note, though, that if the handler is
 327          for an architecture that is a superset of ARCH_INFO, we can't
 328          use that --- it would be perfectly correct for it to install
 329          gdbarch methods that refer to registers / instructions /
 330          other facilities ARCH_INFO doesn't have.
 331
 332          NOTE: kettenis/20021027: There may be more than one machine
 333          type that is compatible with the desired machine type.  Right
 334          now we simply return the first match, which is fine for now.
 335          However, we might want to do something smarter in the future.  */
 336       if (can_run_code_for (arch_info, handler->arch_info))
 337         {
 338           (*handler->init_osabi) (info, gdbarch);
 339           return;
 340         }
 341     }
 342
 343   fprintf_filtered
 344     (gdb_stderr,
 345      "A handler for the OS ABI \"%s\" is not built into this "
 346      "configuration of GDB.  "
 347      "Attempting to continue with the default %s settings",
 348      gdbarch_osabi_name (info.osabi),
 349      bfd_printable_arch_mach (arch_info->arch, arch_info->mach));
 350 }
 351 \f
 352
 353 /* Generic sniffer for ELF flavoured files.  */
 354
 355 void
 356 generic_elf_osabi_sniff_abi_tag_sections (bfd *abfd, asection *sect, void *obj)
 357 {
 358   enum gdb_osabi *os_ident_ptr = obj;
 359   const char *name;
 360   unsigned int sectsize;
 361
 362   name = bfd_get_section_name (abfd, sect);
 363   sectsize = bfd_section_size (abfd, sect);
 364
 365   /* .note.ABI-tag notes, used by GNU/Linux and FreeBSD.  */
 366   if (strcmp (name, ".note.ABI-tag") == 0 && sectsize > 0)
 367     {
 368       unsigned int name_length, data_length, note_type;
 369       char *note;
 370
 371       /* If the section is larger than this, it's probably not what we are
 372          looking for.  */
 373       if (sectsize > 128)
 374         sectsize = 128;
 375
 376       note = alloca (sectsize);
 377
 378       bfd_get_section_contents (abfd, sect, note,
 379                                 (file_ptr) 0, (bfd_size_type) sectsize);
 380
 381       name_length = bfd_h_get_32 (abfd, note);
 382       data_length = bfd_h_get_32 (abfd, note + 4);
 383       note_type   = bfd_h_get_32 (abfd, note + 8);
 384
 385       if (name_length == 4 && data_length == 16 && note_type == NT_GNU_ABI_TAG
 386           && strcmp (note + 12, "GNU") == 0)
 387         {
 388           int os_number = bfd_h_get_32 (abfd, note + 16);
 389
 390           switch (os_number)
 391             {
 392             case GNU_ABI_TAG_LINUX:
 393               *os_ident_ptr = GDB_OSABI_LINUX;
 394               break;
 395
 396             case GNU_ABI_TAG_HURD:
 397               *os_ident_ptr = GDB_OSABI_HURD;
 398               break;
 399
 400             case GNU_ABI_TAG_SOLARIS:
 401               *os_ident_ptr = GDB_OSABI_SOLARIS;
 402               break;
 403
 404             case GNU_ABI_TAG_FREEBSD:
 405               *os_ident_ptr = GDB_OSABI_FREEBSD_ELF;
 406               break;
 407
 408             case GNU_ABI_TAG_NETBSD:
 409               *os_ident_ptr = GDB_OSABI_NETBSD_ELF;
 410               break;
 411
 412             default:
 413               internal_error
 414                 (__FILE__, __LINE__,
 415                  "generic_elf_osabi_sniff_abi_tag_sections: unknown OS number %d",
 416                  os_number);
 417             }
 418           return;
 419         }
 420       else if (name_length == 8 && data_length == 4
 421                && note_type == NT_FREEBSD_ABI_TAG
 422                && strcmp (note + 12, "FreeBSD") == 0)
 423         {
 424           /* XXX Should we check the version here?  Probably not
 425              necessary yet.  */
 426           *os_ident_ptr = GDB_OSABI_FREEBSD_ELF;
 427         }
 428       return;
 429     }
 430
 431   /* .note.netbsd.ident notes, used by NetBSD.  */
 432   if (strcmp (name, ".note.netbsd.ident") == 0 && sectsize > 0)
 433     {
 434       unsigned int name_length, data_length, note_type;
 435       char *note;
 436
 437       /* If the section is larger than this, it's probably not what we are
 438          looking for.  */
 439       if (sectsize > 128)
 440         sectsize = 128;
 441
 442       note = alloca (sectsize);
 443
 444       bfd_get_section_contents (abfd, sect, note,
 445                                 (file_ptr) 0, (bfd_size_type) sectsize);
 446
 447       name_length = bfd_h_get_32 (abfd, note);
 448       data_length = bfd_h_get_32 (abfd, note + 4);
 449       note_type   = bfd_h_get_32 (abfd, note + 8);
 450
 451       if (name_length == 7 && data_length == 4 && note_type == NT_NETBSD_IDENT
 452           && strcmp (note + 12, "NetBSD") == 0)
 453         {
 454           /* XXX Should we check the version here?  Probably not
 455              necessary yet.  */
 456           *os_ident_ptr = GDB_OSABI_NETBSD_ELF;
 457         }
 458       return;
 459     }
 460 }
 461
 462 static enum gdb_osabi
 463 generic_elf_osabi_sniffer (bfd *abfd)
 464 {
 465   unsigned int elfosabi;
 466   enum gdb_osabi osabi = GDB_OSABI_UNKNOWN;
 467
 468   elfosabi = elf_elfheader (abfd)->e_ident[EI_OSABI];
 469
 470   switch (elfosabi)
 471     {
 472     case ELFOSABI_NONE:
 473       /* When elfosabi is ELFOSABI_NONE (0), then the ELF structures in the
 474          file are conforming to the base specification for that machine
 475          (there are no OS-specific extensions).  In order to determine the
 476          real OS in use we must look for OS notes that have been added.  */
 477       bfd_map_over_sections (abfd,
 478                              generic_elf_osabi_sniff_abi_tag_sections,
 479                              &osabi);
 480       break;
 481
 482     case ELFOSABI_FREEBSD:
 483       osabi = GDB_OSABI_FREEBSD_ELF;
 484       break;
 485
 486     case ELFOSABI_NETBSD:
 487       osabi = GDB_OSABI_NETBSD_ELF;
 488       break;
 489
 490     case ELFOSABI_LINUX:
 491       osabi = GDB_OSABI_LINUX;
 492       break;
 493
 494     case ELFOSABI_HURD:
 495       osabi = GDB_OSABI_HURD;
 496       break;
 497
 498     case ELFOSABI_SOLARIS:
 499       osabi = GDB_OSABI_SOLARIS;
 500       break;
 501
 502     case ELFOSABI_HPUX:
 503       osabi = GDB_OSABI_HPUX_ELF;
 504       break;
 505     }
 506
 507   if (osabi == GDB_OSABI_UNKNOWN)
 508     {
 509       /* The FreeBSD folks have been naughty; they stored the string
 510          "FreeBSD" in the padding of the e_ident field of the ELF
 511          header to "brand" their ELF binaries in FreeBSD 3.x.  */
 512       if (strcmp (&elf_elfheader (abfd)->e_ident[8], "FreeBSD") == 0)
 513         osabi = GDB_OSABI_FREEBSD_ELF;
 514     }
 515
 516   return osabi;
 517 }
 518 \f
 519 static void
 520 set_osabi (char *args, int from_tty, struct cmd_list_element *c)
 521 {
 522   struct gdbarch_info info;
 523
 524   if (strcmp (set_osabi_string, "auto") == 0)
 525     user_osabi_state = osabi_auto;
 526   else if (strcmp (set_osabi_string, "default") == 0)
 527     {
 528       user_selected_osabi = GDB_OSABI_DEFAULT;
 529       user_osabi_state = osabi_user;
 530     }
 531   else if (strcmp (set_osabi_string, "none") == 0)
 532     {
 533       user_selected_osabi = GDB_OSABI_UNKNOWN;
 534       user_osabi_state = osabi_user;
 535     }
 536   else
 537     {
 538       int i;
 539       for (i = 1; i < GDB_OSABI_INVALID; i++)
 540         if (strcmp (set_osabi_string, gdbarch_osabi_name (i)) == 0)
 541           {
 542             user_selected_osabi = i;
 543             user_osabi_state = osabi_user;
 544             break;
 545           }
 546       if (i == GDB_OSABI_INVALID)
 547         internal_error (__FILE__, __LINE__,
 548                         "Invalid OS ABI \"%s\" passed to command handler.",
 549                         set_osabi_string);
 550     }
 551
 552   /* NOTE: At some point (true multiple architectures) we'll need to be more
 553      graceful here.  */
 554   gdbarch_info_init (&info);
 555   if (! gdbarch_update_p (info))
 556     internal_error (__FILE__, __LINE__, "Updating OS ABI failed.");
 557 }
 558
 559 static void
 560 show_osabi (char *args, int from_tty)
 561 {
 562   if (user_osabi_state == osabi_auto)
 563     printf_filtered ("The current OS ABI is \"auto\" (currently \"%s\").\n",
 564                      gdbarch_osabi_name (gdbarch_osabi (current_gdbarch)));
 565   else
 566     printf_filtered ("The current OS ABI is \"%s\".\n",
 567                      gdbarch_osabi_name (user_selected_osabi));
 568
 569   if (GDB_OSABI_DEFAULT != GDB_OSABI_UNKNOWN)
 570     printf_filtered ("The default OS ABI is \"%s\".\n",
 571                      gdbarch_osabi_name (GDB_OSABI_DEFAULT));
 572 }
 573 \f
 574 extern initialize_file_ftype _initialize_gdb_osabi; /* -Wmissing-prototype */
 575
 576 void
 577 _initialize_gdb_osabi (void)
 578 {
 579   struct cmd_list_element *c;
 580
 581   if (strcmp (gdb_osabi_names[GDB_OSABI_INVALID], "<invalid>") != 0)
 582     internal_error
 583       (__FILE__, __LINE__,
 584        "_initialize_gdb_osabi: gdb_osabi_names[] is inconsistent");
 585
 586   /* Register a generic sniffer for ELF flavoured files.  */
 587   gdbarch_register_osabi_sniffer (bfd_arch_unknown,
 588                                   bfd_target_elf_flavour,
 589                                   generic_elf_osabi_sniffer);
 590
 591   return;
 592
 593   /* Register the "set osabi" command.  */
 594   c = add_set_enum_cmd ("osabi", class_support, gdb_osabi_available_names,
 595                         &set_osabi_string, "Set OS ABI of target.", &setlist);
 596
 597   set_cmd_sfunc (c, set_osabi);
 598   add_cmd ("osabi", class_support, show_osabi, "Show OS/ABI of target.",
 599            &showlist);
 600   user_osabi_state = osabi_auto;
 601 }