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 void
 287 gdbarch_init_osabi (struct gdbarch_info info, struct gdbarch *gdbarch)
 288 {
 289   const struct bfd_arch_info *arch_info = gdbarch_bfd_arch_info (gdbarch);
 290   const struct bfd_arch_info *compatible;
 291   struct gdb_osabi_handler *handler;
 292
 293   if (info.osabi == GDB_OSABI_UNKNOWN)
 294     {
 295       /* Don't complain about an unknown OSABI.  Assume the user knows
 296          what they are doing.  */
 297       return;
 298     }
 299
 300   for (handler = gdb_osabi_handler_list; handler != NULL;
 301        handler = handler->next)
 302     {
 303       if (handler->osabi != info.osabi)
 304         continue;
 305
 306       /* Check whether the machine type and architecture of the
 307          handler are compatible with the desired machine type and
 308          architecture.
 309
 310          NOTE: kettenis/20021027: There may be more than one machine
 311          type that is compatible with the desired machine type.  Right
 312          now we simply return the first match, which is fine for now.
 313          However, we might want to do something smarter in the future.  */
 314       compatible = arch_info->compatible (arch_info, handler->arch_info);
 315       if (compatible == handler->arch_info)
 316         {
 317           (*handler->init_osabi) (info, gdbarch);
 318           return;
 319         }
 320     }
 321
 322   /* We assume that if GDB_MULTI_ARCH is less than GDB_MULTI_ARCH_TM
 323      that an ABI variant can be supported by overriding definitions in
 324      the tm-file.  */
 325   if (GDB_MULTI_ARCH > GDB_MULTI_ARCH_PARTIAL)
 326     fprintf_filtered
 327       (gdb_stderr,
 328        "A handler for the OS ABI \"%s\" is not built into this "
 329        "configuration of GDB.  "
 330        "Attempting to continue with the default %s settings",
 331        gdbarch_osabi_name (info.osabi),
 332        bfd_printable_arch_mach (arch_info->arch, arch_info->mach));
 333 }
 334 \f
 335
 336 /* Generic sniffer for ELF flavoured files.  */
 337
 338 void
 339 generic_elf_osabi_sniff_abi_tag_sections (bfd *abfd, asection *sect, void *obj)
 340 {
 341   enum gdb_osabi *os_ident_ptr = obj;
 342   const char *name;
 343   unsigned int sectsize;
 344
 345   name = bfd_get_section_name (abfd, sect);
 346   sectsize = bfd_section_size (abfd, sect);
 347
 348   /* .note.ABI-tag notes, used by GNU/Linux and FreeBSD.  */
 349   if (strcmp (name, ".note.ABI-tag") == 0 && sectsize > 0)
 350     {
 351       unsigned int name_length, data_length, note_type;
 352       char *note;
 353
 354       /* If the section is larger than this, it's probably not what we are
 355          looking for.  */
 356       if (sectsize > 128)
 357         sectsize = 128;
 358
 359       note = alloca (sectsize);
 360
 361       bfd_get_section_contents (abfd, sect, note,
 362                                 (file_ptr) 0, (bfd_size_type) sectsize);
 363
 364       name_length = bfd_h_get_32 (abfd, note);
 365       data_length = bfd_h_get_32 (abfd, note + 4);
 366       note_type   = bfd_h_get_32 (abfd, note + 8);
 367
 368       if (name_length == 4 && data_length == 16 && note_type == NT_GNU_ABI_TAG
 369           && strcmp (note + 12, "GNU") == 0)
 370         {
 371           int os_number = bfd_h_get_32 (abfd, note + 16);
 372
 373           switch (os_number)
 374             {
 375             case GNU_ABI_TAG_LINUX:
 376               *os_ident_ptr = GDB_OSABI_LINUX;
 377               break;
 378
 379             case GNU_ABI_TAG_HURD:
 380               *os_ident_ptr = GDB_OSABI_HURD;
 381               break;
 382
 383             case GNU_ABI_TAG_SOLARIS:
 384               *os_ident_ptr = GDB_OSABI_SOLARIS;
 385               break;
 386
 387             default:
 388               internal_error
 389                 (__FILE__, __LINE__,
 390                  "generic_elf_osabi_sniff_abi_tag_sections: unknown OS number %d",
 391                  os_number);
 392             }
 393           return;
 394         }
 395       else if (name_length == 8 && data_length == 4
 396                && note_type == NT_FREEBSD_ABI_TAG
 397                && strcmp (note + 12, "FreeBSD") == 0)
 398         {
 399           /* XXX Should we check the version here?  Probably not
 400              necessary yet.  */
 401           *os_ident_ptr = GDB_OSABI_FREEBSD_ELF;
 402         }
 403       return;
 404     }
 405
 406   /* .note.netbsd.ident notes, used by NetBSD.  */
 407   if (strcmp (name, ".note.netbsd.ident") == 0 && sectsize > 0)
 408     {
 409       unsigned int name_length, data_length, note_type;
 410       char *note;
 411
 412       /* If the section is larger than this, it's probably not what we are
 413          looking for.  */
 414       if (sectsize > 128)
 415         sectsize = 128;
 416
 417       note = alloca (sectsize);
 418
 419       bfd_get_section_contents (abfd, sect, note,
 420                                 (file_ptr) 0, (bfd_size_type) sectsize);
 421
 422       name_length = bfd_h_get_32 (abfd, note);
 423       data_length = bfd_h_get_32 (abfd, note + 4);
 424       note_type   = bfd_h_get_32 (abfd, note + 8);
 425
 426       if (name_length == 7 && data_length == 4 && note_type == NT_NETBSD_IDENT
 427           && strcmp (note + 12, "NetBSD") == 0)
 428         {
 429           /* XXX Should we check the version here?  Probably not
 430              necessary yet.  */
 431           *os_ident_ptr = GDB_OSABI_NETBSD_ELF;
 432         }
 433       return;
 434     }
 435 }
 436
 437 static enum gdb_osabi
 438 generic_elf_osabi_sniffer (bfd *abfd)
 439 {
 440   unsigned int elfosabi;
 441   enum gdb_osabi osabi = GDB_OSABI_UNKNOWN;
 442
 443   elfosabi = elf_elfheader (abfd)->e_ident[EI_OSABI];
 444
 445   switch (elfosabi)
 446     {
 447     case ELFOSABI_NONE:
 448       /* When elfosabi is ELFOSABI_NONE (0), then the ELF structures in the
 449          file are conforming to the base specification for that machine
 450          (there are no OS-specific extensions).  In order to determine the
 451          real OS in use we must look for OS notes that have been added.  */
 452       bfd_map_over_sections (abfd,
 453                              generic_elf_osabi_sniff_abi_tag_sections,
 454                              &osabi);
 455       break;
 456
 457     case ELFOSABI_FREEBSD:
 458       osabi = GDB_OSABI_FREEBSD_ELF;
 459       break;
 460
 461     case ELFOSABI_NETBSD:
 462       osabi = GDB_OSABI_NETBSD_ELF;
 463       break;
 464
 465     case ELFOSABI_LINUX:
 466       osabi = GDB_OSABI_LINUX;
 467       break;
 468
 469     case ELFOSABI_HURD:
 470       osabi = GDB_OSABI_HURD;
 471       break;
 472
 473     case ELFOSABI_SOLARIS:
 474       osabi = GDB_OSABI_SOLARIS;
 475       break;
 476
 477     case ELFOSABI_HPUX:
 478       osabi = GDB_OSABI_HPUX_ELF;
 479       break;
 480     }
 481
 482   if (osabi == GDB_OSABI_UNKNOWN)
 483     {
 484       /* The FreeBSD folks have been naughty; they stored the string
 485          "FreeBSD" in the padding of the e_ident field of the ELF
 486          header to "brand" their ELF binaries in FreeBSD 3.x.  */
 487       if (strcmp (&elf_elfheader (abfd)->e_ident[8], "FreeBSD") == 0)
 488         osabi = GDB_OSABI_FREEBSD_ELF;
 489     }
 490
 491   return osabi;
 492 }
 493 \f
 494 static void
 495 set_osabi (char *args, int from_tty, struct cmd_list_element *c)
 496 {
 497   struct gdbarch_info info;
 498
 499   if (strcmp (set_osabi_string, "auto") == 0)
 500     user_osabi_state = osabi_auto;
 501   else if (strcmp (set_osabi_string, "default") == 0)
 502     {
 503       user_selected_osabi = GDB_OSABI_DEFAULT;
 504       user_osabi_state = osabi_user;
 505     }
 506   else if (strcmp (set_osabi_string, "none") == 0)
 507     {
 508       user_selected_osabi = GDB_OSABI_UNKNOWN;
 509       user_osabi_state = osabi_user;
 510     }
 511   else
 512     {
 513       int i;
 514       for (i = 1; i < GDB_OSABI_INVALID; i++)
 515         if (strcmp (set_osabi_string, gdbarch_osabi_name (i)) == 0)
 516           {
 517             user_selected_osabi = i;
 518             user_osabi_state = osabi_user;
 519             break;
 520           }
 521       if (i == GDB_OSABI_INVALID)
 522         internal_error (__FILE__, __LINE__,
 523                         "Invalid OS ABI \"%s\" passed to command handler.",
 524                         set_osabi_string);
 525     }
 526
 527   /* NOTE: At some point (true multiple architectures) we'll need to be more
 528      graceful here.  */
 529   gdbarch_info_init (&info);
 530   if (! gdbarch_update_p (info))
 531     internal_error (__FILE__, __LINE__, "Updating OS ABI failed.");
 532 }
 533
 534 static void
 535 show_osabi (char *args, int from_tty)
 536 {
 537   if (user_osabi_state == osabi_auto)
 538     printf_filtered ("The current OS ABI is \"auto\" (currently \"%s\").\n",
 539                      gdbarch_osabi_name (gdbarch_osabi (current_gdbarch)));
 540   else
 541     printf_filtered ("The current OS ABI is \"%s\".\n",
 542                      gdbarch_osabi_name (user_selected_osabi));
 543
 544   if (GDB_OSABI_DEFAULT != GDB_OSABI_UNKNOWN)
 545     printf_filtered ("The default OS ABI is \"%s\".\n",
 546                      gdbarch_osabi_name (GDB_OSABI_DEFAULT));
 547 }
 548 \f
 549 extern initialize_file_ftype _initialize_gdb_osabi; /* -Wmissing-prototype */
 550
 551 void
 552 _initialize_gdb_osabi (void)
 553 {
 554   struct cmd_list_element *c;
 555
 556   if (strcmp (gdb_osabi_names[GDB_OSABI_INVALID], "<invalid>") != 0)
 557     internal_error
 558       (__FILE__, __LINE__,
 559        "_initialize_gdb_osabi: gdb_osabi_names[] is inconsistent");
 560
 561   /* Register a generic sniffer for ELF flavoured files.  */
 562   gdbarch_register_osabi_sniffer (bfd_arch_unknown,
 563                                   bfd_target_elf_flavour,
 564                                   generic_elf_osabi_sniffer);
 565
 566   if (!GDB_MULTI_ARCH)
 567     return;
 568
 569   /* Register the "set osabi" command.  */
 570   c = add_set_enum_cmd ("osabi", class_support, gdb_osabi_available_names,
 571                         &set_osabi_string, "Set OS ABI of target.", &setlist);
 572
 573   set_cmd_sfunc (c, set_osabi);
 574   add_cmd ("osabi", class_support, show_osabi, "Show OS/ABI of target.",
 575            &showlist);
 576   user_osabi_state = osabi_auto;
 577 }