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   "OpenBSD ELF",
  64   "Windows CE",
  65   "DJGPP",
  66   "NetWare",
  67   "Irix",
  68   "LynxOS",
  69   "Interix",
  70   "HP/UX ELF",
  71   "HP/UX SOM",
  72
  73   "ARM EABI v1",
  74   "ARM EABI v2",
  75   "ARM APCS",
  76   "QNX Neutrino",
  77
  78   "Cygwin",
  79
  80   "<invalid>"
  81 };
  82
  83 const char *
  84 gdbarch_osabi_name (enum gdb_osabi osabi)
  85 {
  86   if (osabi >= GDB_OSABI_UNKNOWN && osabi < GDB_OSABI_INVALID)
  87     return gdb_osabi_names[osabi];
  88
  89   return gdb_osabi_names[GDB_OSABI_INVALID];
  90 }
  91
  92 /* Handler for a given architecture/OS ABI pair.  There should be only
  93    one handler for a given OS ABI each architecture family.  */
  94 struct gdb_osabi_handler
  95 {
  96   struct gdb_osabi_handler *next;
  97   const struct bfd_arch_info *arch_info;
  98   enum gdb_osabi osabi;
  99   void (*init_osabi)(struct gdbarch_info, struct gdbarch *);
 100 };
 101
 102 static struct gdb_osabi_handler *gdb_osabi_handler_list;
 103
 104 void
 105 gdbarch_register_osabi (enum bfd_architecture arch, unsigned long machine,
 106                         enum gdb_osabi osabi,
 107                         void (*init_osabi)(struct gdbarch_info,
 108                                            struct gdbarch *))
 109 {
 110   struct gdb_osabi_handler **handler_p;
 111   const struct bfd_arch_info *arch_info = bfd_lookup_arch (arch, machine);
 112   const char **name_ptr;
 113
 114   /* Registering an OS ABI handler for "unknown" is not allowed.  */
 115   if (osabi == GDB_OSABI_UNKNOWN)
 116     {
 117       internal_error
 118         (__FILE__, __LINE__,
 119          "gdbarch_register_osabi: An attempt to register a handler for "
 120          "OS ABI \"%s\" for architecture %s was made.  The handler will "
 121          "not be registered",
 122          gdbarch_osabi_name (osabi),
 123          bfd_printable_arch_mach (arch, machine));
 124       return;
 125     }
 126
 127   gdb_assert (arch_info);
 128
 129   for (handler_p = &gdb_osabi_handler_list; *handler_p != NULL;
 130        handler_p = &(*handler_p)->next)
 131     {
 132       if ((*handler_p)->arch_info == arch_info
 133           && (*handler_p)->osabi == osabi)
 134         {
 135           internal_error
 136             (__FILE__, __LINE__,
 137              "gdbarch_register_osabi: A handler for OS ABI \"%s\" "
 138              "has already been registered for architecture %s",
 139              gdbarch_osabi_name (osabi),
 140              arch_info->printable_name);
 141           /* If user wants to continue, override previous definition.  */
 142           (*handler_p)->init_osabi = init_osabi;
 143           return;
 144         }
 145     }
 146
 147   (*handler_p)
 148     = (struct gdb_osabi_handler *) xmalloc (sizeof (struct gdb_osabi_handler));
 149   (*handler_p)->next = NULL;
 150   (*handler_p)->arch_info = arch_info;
 151   (*handler_p)->osabi = osabi;
 152   (*handler_p)->init_osabi = init_osabi;
 153
 154   /* Add this OS ABI to the list of enum values for "set osabi", if it isn't
 155      already there.  */
 156   for (name_ptr = gdb_osabi_available_names; *name_ptr; name_ptr ++)
 157     {
 158       if (*name_ptr == gdbarch_osabi_name (osabi))
 159         return;
 160     }
 161   *name_ptr++ = gdbarch_osabi_name (osabi);
 162   *name_ptr = NULL;
 163 }
 164 \f
 165
 166 /* Sniffer to find the OS ABI for a given file's architecture and flavour.
 167    It is legal to have multiple sniffers for each arch/flavour pair, to
 168    disambiguate one OS's a.out from another, for example.  The first sniffer
 169    to return something other than GDB_OSABI_UNKNOWN wins, so a sniffer should
 170    be careful to claim a file only if it knows for sure what it is.  */
 171 struct gdb_osabi_sniffer
 172 {
 173   struct gdb_osabi_sniffer *next;
 174   enum bfd_architecture arch;   /* bfd_arch_unknown == wildcard */
 175   enum bfd_flavour flavour;
 176   enum gdb_osabi (*sniffer)(bfd *);
 177 };
 178
 179 static struct gdb_osabi_sniffer *gdb_osabi_sniffer_list;
 180
 181 void
 182 gdbarch_register_osabi_sniffer (enum bfd_architecture arch,
 183                                 enum bfd_flavour flavour,
 184                                 enum gdb_osabi (*sniffer_fn)(bfd *))
 185 {
 186   struct gdb_osabi_sniffer *sniffer;
 187
 188   sniffer =
 189     (struct gdb_osabi_sniffer *) xmalloc (sizeof (struct gdb_osabi_sniffer));
 190   sniffer->arch = arch;
 191   sniffer->flavour = flavour;
 192   sniffer->sniffer = sniffer_fn;
 193
 194   sniffer->next = gdb_osabi_sniffer_list;
 195   gdb_osabi_sniffer_list = sniffer;
 196 }
 197 \f
 198
 199 enum gdb_osabi
 200 gdbarch_lookup_osabi (bfd *abfd)
 201 {
 202   struct gdb_osabi_sniffer *sniffer;
 203   enum gdb_osabi osabi, match;
 204   int match_specific;
 205
 206   /* If we aren't in "auto" mode, return the specified OS ABI.  */
 207   if (user_osabi_state == osabi_user)
 208     return user_selected_osabi;
 209
 210   /* If we don't have a binary, return the default OS ABI (if set) or
 211      an inconclusive result (otherwise).  */
 212   if (abfd == NULL)
 213     {
 214       if (GDB_OSABI_DEFAULT != GDB_OSABI_UNKNOWN)
 215         return GDB_OSABI_DEFAULT;
 216       else
 217         return GDB_OSABI_UNINITIALIZED;
 218     }
 219
 220   match = GDB_OSABI_UNKNOWN;
 221   match_specific = 0;
 222
 223   for (sniffer = gdb_osabi_sniffer_list; sniffer != NULL;
 224        sniffer = sniffer->next)
 225     {
 226       if ((sniffer->arch == bfd_arch_unknown /* wildcard */
 227            || sniffer->arch == bfd_get_arch (abfd))
 228           && sniffer->flavour == bfd_get_flavour (abfd))
 229         {
 230           osabi = (*sniffer->sniffer) (abfd);
 231           if (osabi < GDB_OSABI_UNKNOWN || osabi >= GDB_OSABI_INVALID)
 232             {
 233               internal_error
 234                 (__FILE__, __LINE__,
 235                  "gdbarch_lookup_osabi: invalid OS ABI (%d) from sniffer "
 236                  "for architecture %s flavour %d",
 237                  (int) osabi,
 238                  bfd_printable_arch_mach (bfd_get_arch (abfd), 0),
 239                  (int) bfd_get_flavour (abfd));
 240             }
 241           else if (osabi != GDB_OSABI_UNKNOWN)
 242             {
 243               /* A specific sniffer always overrides a generic sniffer.
 244                  Croak on multiple match if the two matches are of the
 245                  same class.  If the user wishes to continue, we'll use
 246                  the first match.  */
 247               if (match != GDB_OSABI_UNKNOWN)
 248                 {
 249                   if ((match_specific && sniffer->arch != bfd_arch_unknown)
 250                    || (!match_specific && sniffer->arch == bfd_arch_unknown))
 251                     {
 252                       internal_error
 253                         (__FILE__, __LINE__,
 254                          "gdbarch_lookup_osabi: multiple %sspecific OS ABI "
 255                          "match for architecture %s flavour %d: first "
 256                          "match \"%s\", second match \"%s\"",
 257                          match_specific ? "" : "non-",
 258                          bfd_printable_arch_mach (bfd_get_arch (abfd), 0),
 259                          (int) bfd_get_flavour (abfd),
 260                          gdbarch_osabi_name (match),
 261                          gdbarch_osabi_name (osabi));
 262                     }
 263                   else if (sniffer->arch != bfd_arch_unknown)
 264                     {
 265                       match = osabi;
 266                       match_specific = 1;
 267                     }
 268                 }
 269               else
 270                 {
 271                   match = osabi;
 272                   if (sniffer->arch != bfd_arch_unknown)
 273                     match_specific = 1;
 274                 }
 275             }
 276         }
 277     }
 278
 279   /* If we didn't find a match, but a default was specified at configure
 280      time, return the default.  */
 281   if (GDB_OSABI_DEFAULT != GDB_OSABI_UNKNOWN && match == GDB_OSABI_UNKNOWN)
 282     return GDB_OSABI_DEFAULT;
 283   else
 284     return match;
 285 }
 286
 287
 288 /* Return non-zero if architecture A can run code written for
 289    architecture B.  */
 290 static int
 291 can_run_code_for (const struct bfd_arch_info *a, const struct bfd_arch_info *b)
 292 {
 293   /* BFD's 'A->compatible (A, B)' functions return zero if A and B are
 294      incompatible.  But if they are compatible, it returns the 'more
 295      featureful' of the two arches.  That is, if A can run code
 296      written for B, but B can't run code written for A, then it'll
 297      return A.
 298
 299      struct bfd_arch_info objects are singletons: that is, there's
 300      supposed to be exactly one instance for a given machine.  So you
 301      can tell whether two are equivalent by comparing pointers.  */
 302   return (a == b || a->compatible (a, b) == a);
 303 }
 304
 305
 306 void
 307 gdbarch_init_osabi (struct gdbarch_info info, struct gdbarch *gdbarch)
 308 {
 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       /* NOTE: cagney/2003-10-23: The code for "a can_run_code_for b"
 337          is implemented using BFD's compatible method (a->compatible
 338          (b) == a -- the lowest common denominator between a and b is
 339          a).  That method's definition of compatible may not be as you
 340          expect.  For instance the test "amd64 can run code for i386"
 341          (or more generally "64-bit ISA can run code for the 32-bit
 342          ISA").  BFD doesn't normally consider 32-bit and 64-bit
 343          "compatible" so it doesn't succeed.  */
 344       if (can_run_code_for (info.bfd_arch_info, handler->arch_info))
 345         {
 346           (*handler->init_osabi) (info, gdbarch);
 347           return;
 348         }
 349     }
 350
 351   warning
 352     ("A handler for the OS ABI \"%s\" is not built into this configuration\n"
 353      "of GDB.  Attempting to continue with the default %s settings.\n",
 354      gdbarch_osabi_name (info.osabi),
 355      info.bfd_arch_info->printable_name);
 356 }
 357 \f
 358
 359 /* Generic sniffer for ELF flavoured files.  */
 360
 361 void
 362 generic_elf_osabi_sniff_abi_tag_sections (bfd *abfd, asection *sect, void *obj)
 363 {
 364   enum gdb_osabi *os_ident_ptr = obj;
 365   const char *name;
 366   unsigned int sectsize;
 367
 368   name = bfd_get_section_name (abfd, sect);
 369   sectsize = bfd_section_size (abfd, sect);
 370
 371   /* .note.ABI-tag notes, used by GNU/Linux and FreeBSD.  */
 372   if (strcmp (name, ".note.ABI-tag") == 0 && sectsize > 0)
 373     {
 374       unsigned int name_length, data_length, note_type;
 375       char *note;
 376
 377       /* If the section is larger than this, it's probably not what we are
 378          looking for.  */
 379       if (sectsize > 128)
 380         sectsize = 128;
 381
 382       note = alloca (sectsize);
 383
 384       bfd_get_section_contents (abfd, sect, note,
 385                                 (file_ptr) 0, (bfd_size_type) sectsize);
 386
 387       name_length = bfd_h_get_32 (abfd, note);
 388       data_length = bfd_h_get_32 (abfd, note + 4);
 389       note_type   = bfd_h_get_32 (abfd, note + 8);
 390
 391       if (name_length == 4 && data_length == 16 && note_type == NT_GNU_ABI_TAG
 392           && strcmp (note + 12, "GNU") == 0)
 393         {
 394           int os_number = bfd_h_get_32 (abfd, note + 16);
 395
 396           switch (os_number)
 397             {
 398             case GNU_ABI_TAG_LINUX:
 399               *os_ident_ptr = GDB_OSABI_LINUX;
 400               break;
 401
 402             case GNU_ABI_TAG_HURD:
 403               *os_ident_ptr = GDB_OSABI_HURD;
 404               break;
 405
 406             case GNU_ABI_TAG_SOLARIS:
 407               *os_ident_ptr = GDB_OSABI_SOLARIS;
 408               break;
 409
 410             case GNU_ABI_TAG_FREEBSD:
 411               *os_ident_ptr = GDB_OSABI_FREEBSD_ELF;
 412               break;
 413
 414             case GNU_ABI_TAG_NETBSD:
 415               *os_ident_ptr = GDB_OSABI_NETBSD_ELF;
 416               break;
 417
 418             default:
 419               internal_error
 420                 (__FILE__, __LINE__,
 421                  "generic_elf_osabi_sniff_abi_tag_sections: unknown OS number %d",
 422                  os_number);
 423             }
 424           return;
 425         }
 426       else if (name_length == 8 && data_length == 4
 427                && note_type == NT_FREEBSD_ABI_TAG
 428                && strcmp (note + 12, "FreeBSD") == 0)
 429         {
 430           /* XXX Should we check the version here?  Probably not
 431              necessary yet.  */
 432           *os_ident_ptr = GDB_OSABI_FREEBSD_ELF;
 433         }
 434       return;
 435     }
 436
 437   /* .note.netbsd.ident notes, used by NetBSD.  */
 438   if (strcmp (name, ".note.netbsd.ident") == 0 && sectsize > 0)
 439     {
 440       unsigned int name_length, data_length, note_type;
 441       char *note;
 442
 443       /* If the section is larger than this, it's probably not what we are
 444          looking for.  */
 445       if (sectsize > 128)
 446         sectsize = 128;
 447
 448       note = alloca (sectsize);
 449
 450       bfd_get_section_contents (abfd, sect, note,
 451                                 (file_ptr) 0, (bfd_size_type) sectsize);
 452
 453       name_length = bfd_h_get_32 (abfd, note);
 454       data_length = bfd_h_get_32 (abfd, note + 4);
 455       note_type   = bfd_h_get_32 (abfd, note + 8);
 456
 457       if (name_length == 7 && data_length == 4 && note_type == NT_NETBSD_IDENT
 458           && strcmp (note + 12, "NetBSD") == 0)
 459         {
 460           /* XXX Should we check the version here?  Probably not
 461              necessary yet.  */
 462           *os_ident_ptr = GDB_OSABI_NETBSD_ELF;
 463         }
 464       return;
 465     }
 466
 467   /* .note.netbsdcore.procinfo notes, used by NetBSD.  */
 468   if (strcmp (name, ".note.netbsdcore.procinfo") == 0 && sectsize > 0)
 469     {
 470       *os_ident_ptr = GDB_OSABI_NETBSD_ELF;
 471       return;
 472     }
 473 }
 474
 475 static enum gdb_osabi
 476 generic_elf_osabi_sniffer (bfd *abfd)
 477 {
 478   unsigned int elfosabi;
 479   enum gdb_osabi osabi = GDB_OSABI_UNKNOWN;
 480
 481   elfosabi = elf_elfheader (abfd)->e_ident[EI_OSABI];
 482
 483   switch (elfosabi)
 484     {
 485     case ELFOSABI_NONE:
 486       /* When elfosabi is ELFOSABI_NONE (0), then the ELF structures in the
 487          file are conforming to the base specification for that machine
 488          (there are no OS-specific extensions).  In order to determine the
 489          real OS in use we must look for OS notes that have been added.  */
 490       bfd_map_over_sections (abfd,
 491                              generic_elf_osabi_sniff_abi_tag_sections,
 492                              &osabi);
 493       break;
 494
 495     case ELFOSABI_FREEBSD:
 496       osabi = GDB_OSABI_FREEBSD_ELF;
 497       break;
 498
 499     case ELFOSABI_NETBSD:
 500       osabi = GDB_OSABI_NETBSD_ELF;
 501       break;
 502
 503     case ELFOSABI_LINUX:
 504       osabi = GDB_OSABI_LINUX;
 505       break;
 506
 507     case ELFOSABI_HURD:
 508       osabi = GDB_OSABI_HURD;
 509       break;
 510
 511     case ELFOSABI_SOLARIS:
 512       osabi = GDB_OSABI_SOLARIS;
 513       break;
 514
 515     case ELFOSABI_HPUX:
 516       osabi = GDB_OSABI_HPUX_ELF;
 517       break;
 518     }
 519
 520   if (osabi == GDB_OSABI_UNKNOWN)
 521     {
 522       /* The FreeBSD folks have been naughty; they stored the string
 523          "FreeBSD" in the padding of the e_ident field of the ELF
 524          header to "brand" their ELF binaries in FreeBSD 3.x.  */
 525       if (strcmp (&elf_elfheader (abfd)->e_ident[8], "FreeBSD") == 0)
 526         osabi = GDB_OSABI_FREEBSD_ELF;
 527     }
 528
 529   return osabi;
 530 }
 531 \f
 532 static void
 533 set_osabi (char *args, int from_tty, struct cmd_list_element *c)
 534 {
 535   struct gdbarch_info info;
 536
 537   if (strcmp (set_osabi_string, "auto") == 0)
 538     user_osabi_state = osabi_auto;
 539   else if (strcmp (set_osabi_string, "default") == 0)
 540     {
 541       user_selected_osabi = GDB_OSABI_DEFAULT;
 542       user_osabi_state = osabi_user;
 543     }
 544   else if (strcmp (set_osabi_string, "none") == 0)
 545     {
 546       user_selected_osabi = GDB_OSABI_UNKNOWN;
 547       user_osabi_state = osabi_user;
 548     }
 549   else
 550     {
 551       int i;
 552       for (i = 1; i < GDB_OSABI_INVALID; i++)
 553         if (strcmp (set_osabi_string, gdbarch_osabi_name (i)) == 0)
 554           {
 555             user_selected_osabi = i;
 556             user_osabi_state = osabi_user;
 557             break;
 558           }
 559       if (i == GDB_OSABI_INVALID)
 560         internal_error (__FILE__, __LINE__,
 561                         "Invalid OS ABI \"%s\" passed to command handler.",
 562                         set_osabi_string);
 563     }
 564
 565   /* NOTE: At some point (true multiple architectures) we'll need to be more
 566      graceful here.  */
 567   gdbarch_info_init (&info);
 568   if (! gdbarch_update_p (info))
 569     internal_error (__FILE__, __LINE__, "Updating OS ABI failed.");
 570 }
 571
 572 static void
 573 show_osabi (char *args, int from_tty)
 574 {
 575   if (user_osabi_state == osabi_auto)
 576     printf_filtered ("The current OS ABI is \"auto\" (currently \"%s\").\n",
 577                      gdbarch_osabi_name (gdbarch_osabi (current_gdbarch)));
 578   else
 579     printf_filtered ("The current OS ABI is \"%s\".\n",
 580                      gdbarch_osabi_name (user_selected_osabi));
 581
 582   if (GDB_OSABI_DEFAULT != GDB_OSABI_UNKNOWN)
 583     printf_filtered ("The default OS ABI is \"%s\".\n",
 584                      gdbarch_osabi_name (GDB_OSABI_DEFAULT));
 585 }
 586 \f
 587 extern initialize_file_ftype _initialize_gdb_osabi; /* -Wmissing-prototype */
 588
 589 void
 590 _initialize_gdb_osabi (void)
 591 {
 592   struct cmd_list_element *c;
 593
 594   if (strcmp (gdb_osabi_names[GDB_OSABI_INVALID], "<invalid>") != 0)
 595     internal_error
 596       (__FILE__, __LINE__,
 597        "_initialize_gdb_osabi: gdb_osabi_names[] is inconsistent");
 598
 599   /* Register a generic sniffer for ELF flavoured files.  */
 600   gdbarch_register_osabi_sniffer (bfd_arch_unknown,
 601                                   bfd_target_elf_flavour,
 602                                   generic_elf_osabi_sniffer);
 603
 604   /* Register the "set osabi" command.  */
 605   c = add_set_enum_cmd ("osabi", class_support, gdb_osabi_available_names,
 606                         &set_osabi_string, "Set OS ABI of target.", &setlist);
 607
 608   set_cmd_sfunc (c, set_osabi);
 609   add_cmd ("osabi", class_support, show_osabi, "Show OS/ABI of target.",
 610            &showlist);
 611   user_osabi_state = osabi_auto;
 612 }