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 singletons: that is, there's
 299      supposed to be exactly one instance for a given machine.  So you
 300      can tell 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   struct gdb_osabi_handler *handler;
 309
 310   if (info.osabi == GDB_OSABI_UNKNOWN)
 311     {
 312       /* Don't complain about an unknown OSABI.  Assume the user knows
 313          what they are doing.  */
 314       return;
 315     }
 316
 317   for (handler = gdb_osabi_handler_list; handler != NULL;
 318        handler = handler->next)
 319     {
 320       if (handler->osabi != info.osabi)
 321         continue;
 322
 323       /* If the architecture described by ARCH_INFO can run code for
 324          the architcture we registered the handler for, then the
 325          handler is applicable.  Note, though, that if the handler is
 326          for an architecture that is a superset of ARCH_INFO, we can't
 327          use that --- it would be perfectly correct for it to install
 328          gdbarch methods that refer to registers / instructions /
 329          other facilities ARCH_INFO doesn't have.
 330
 331          NOTE: kettenis/20021027: There may be more than one machine
 332          type that is compatible with the desired machine type.  Right
 333          now we simply return the first match, which is fine for now.
 334          However, we might want to do something smarter in the future.  */
 335       /* NOTE: cagney/2003-10-23: The code for "a can_run_code_for b"
 336          is implemented using BFD's compatible method (a->compatible
 337          (b) == a -- the lowest common denominator between a and b is
 338          a).  That method's definition of compatible may not be as you
 339          expect.  For instance the test "amd64 can run code for i386"
 340          (or more generally "64-bit ISA can run code for the 32-bit
 341          ISA").  BFD doesn't normally consider 32-bit and 64-bit
 342          "compatible" so it doesn't succeed.  */
 343       if (can_run_code_for (info.bfd_arch_info, handler->arch_info))
 344         {
 345           (*handler->init_osabi) (info, gdbarch);
 346           return;
 347         }
 348     }
 349
 350   warning ("A handler for the OS ABI \"%s\" is not built into this "
 351            "configuration of GDB.  "
 352            "Attempting to continue with the default %s settings",
 353            gdbarch_osabi_name (info.osabi),
 354            info.bfd_arch_info->printable_name);
 355 }
 356 \f
 357
 358 /* Generic sniffer for ELF flavoured files.  */
 359
 360 void
 361 generic_elf_osabi_sniff_abi_tag_sections (bfd *abfd, asection *sect, void *obj)
 362 {
 363   enum gdb_osabi *os_ident_ptr = obj;
 364   const char *name;
 365   unsigned int sectsize;
 366
 367   name = bfd_get_section_name (abfd, sect);
 368   sectsize = bfd_section_size (abfd, sect);
 369
 370   /* .note.ABI-tag notes, used by GNU/Linux and FreeBSD.  */
 371   if (strcmp (name, ".note.ABI-tag") == 0 && sectsize > 0)
 372     {
 373       unsigned int name_length, data_length, note_type;
 374       char *note;
 375
 376       /* If the section is larger than this, it's probably not what we are
 377          looking for.  */
 378       if (sectsize > 128)
 379         sectsize = 128;
 380
 381       note = alloca (sectsize);
 382
 383       bfd_get_section_contents (abfd, sect, note,
 384                                 (file_ptr) 0, (bfd_size_type) sectsize);
 385
 386       name_length = bfd_h_get_32 (abfd, note);
 387       data_length = bfd_h_get_32 (abfd, note + 4);
 388       note_type   = bfd_h_get_32 (abfd, note + 8);
 389
 390       if (name_length == 4 && data_length == 16 && note_type == NT_GNU_ABI_TAG
 391           && strcmp (note + 12, "GNU") == 0)
 392         {
 393           int os_number = bfd_h_get_32 (abfd, note + 16);
 394
 395           switch (os_number)
 396             {
 397             case GNU_ABI_TAG_LINUX:
 398               *os_ident_ptr = GDB_OSABI_LINUX;
 399               break;
 400
 401             case GNU_ABI_TAG_HURD:
 402               *os_ident_ptr = GDB_OSABI_HURD;
 403               break;
 404
 405             case GNU_ABI_TAG_SOLARIS:
 406               *os_ident_ptr = GDB_OSABI_SOLARIS;
 407               break;
 408
 409             case GNU_ABI_TAG_FREEBSD:
 410               *os_ident_ptr = GDB_OSABI_FREEBSD_ELF;
 411               break;
 412
 413             case GNU_ABI_TAG_NETBSD:
 414               *os_ident_ptr = GDB_OSABI_NETBSD_ELF;
 415               break;
 416
 417             default:
 418               internal_error
 419                 (__FILE__, __LINE__,
 420                  "generic_elf_osabi_sniff_abi_tag_sections: unknown OS number %d",
 421                  os_number);
 422             }
 423           return;
 424         }
 425       else if (name_length == 8 && data_length == 4
 426                && note_type == NT_FREEBSD_ABI_TAG
 427                && strcmp (note + 12, "FreeBSD") == 0)
 428         {
 429           /* XXX Should we check the version here?  Probably not
 430              necessary yet.  */
 431           *os_ident_ptr = GDB_OSABI_FREEBSD_ELF;
 432         }
 433       return;
 434     }
 435
 436   /* .note.netbsd.ident notes, used by NetBSD.  */
 437   if (strcmp (name, ".note.netbsd.ident") == 0 && sectsize > 0)
 438     {
 439       unsigned int name_length, data_length, note_type;
 440       char *note;
 441
 442       /* If the section is larger than this, it's probably not what we are
 443          looking for.  */
 444       if (sectsize > 128)
 445         sectsize = 128;
 446
 447       note = alloca (sectsize);
 448
 449       bfd_get_section_contents (abfd, sect, note,
 450                                 (file_ptr) 0, (bfd_size_type) sectsize);
 451
 452       name_length = bfd_h_get_32 (abfd, note);
 453       data_length = bfd_h_get_32 (abfd, note + 4);
 454       note_type   = bfd_h_get_32 (abfd, note + 8);
 455
 456       if (name_length == 7 && data_length == 4 && note_type == NT_NETBSD_IDENT
 457           && strcmp (note + 12, "NetBSD") == 0)
 458         {
 459           /* XXX Should we check the version here?  Probably not
 460              necessary yet.  */
 461           *os_ident_ptr = GDB_OSABI_NETBSD_ELF;
 462         }
 463       return;
 464     }
 465 }
 466
 467 static enum gdb_osabi
 468 generic_elf_osabi_sniffer (bfd *abfd)
 469 {
 470   unsigned int elfosabi;
 471   enum gdb_osabi osabi = GDB_OSABI_UNKNOWN;
 472
 473   elfosabi = elf_elfheader (abfd)->e_ident[EI_OSABI];
 474
 475   switch (elfosabi)
 476     {
 477     case ELFOSABI_NONE:
 478       /* When elfosabi is ELFOSABI_NONE (0), then the ELF structures in the
 479          file are conforming to the base specification for that machine
 480          (there are no OS-specific extensions).  In order to determine the
 481          real OS in use we must look for OS notes that have been added.  */
 482       bfd_map_over_sections (abfd,
 483                              generic_elf_osabi_sniff_abi_tag_sections,
 484                              &osabi);
 485       break;
 486
 487     case ELFOSABI_FREEBSD:
 488       osabi = GDB_OSABI_FREEBSD_ELF;
 489       break;
 490
 491     case ELFOSABI_NETBSD:
 492       osabi = GDB_OSABI_NETBSD_ELF;
 493       break;
 494
 495     case ELFOSABI_LINUX:
 496       osabi = GDB_OSABI_LINUX;
 497       break;
 498
 499     case ELFOSABI_HURD:
 500       osabi = GDB_OSABI_HURD;
 501       break;
 502
 503     case ELFOSABI_SOLARIS:
 504       osabi = GDB_OSABI_SOLARIS;
 505       break;
 506
 507     case ELFOSABI_HPUX:
 508       osabi = GDB_OSABI_HPUX_ELF;
 509       break;
 510     }
 511
 512   if (osabi == GDB_OSABI_UNKNOWN)
 513     {
 514       /* The FreeBSD folks have been naughty; they stored the string
 515          "FreeBSD" in the padding of the e_ident field of the ELF
 516          header to "brand" their ELF binaries in FreeBSD 3.x.  */
 517       if (strcmp (&elf_elfheader (abfd)->e_ident[8], "FreeBSD") == 0)
 518         osabi = GDB_OSABI_FREEBSD_ELF;
 519     }
 520
 521   return osabi;
 522 }
 523 \f
 524 static void
 525 set_osabi (char *args, int from_tty, struct cmd_list_element *c)
 526 {
 527   struct gdbarch_info info;
 528
 529   if (strcmp (set_osabi_string, "auto") == 0)
 530     user_osabi_state = osabi_auto;
 531   else if (strcmp (set_osabi_string, "default") == 0)
 532     {
 533       user_selected_osabi = GDB_OSABI_DEFAULT;
 534       user_osabi_state = osabi_user;
 535     }
 536   else if (strcmp (set_osabi_string, "none") == 0)
 537     {
 538       user_selected_osabi = GDB_OSABI_UNKNOWN;
 539       user_osabi_state = osabi_user;
 540     }
 541   else
 542     {
 543       int i;
 544       for (i = 1; i < GDB_OSABI_INVALID; i++)
 545         if (strcmp (set_osabi_string, gdbarch_osabi_name (i)) == 0)
 546           {
 547             user_selected_osabi = i;
 548             user_osabi_state = osabi_user;
 549             break;
 550           }
 551       if (i == GDB_OSABI_INVALID)
 552         internal_error (__FILE__, __LINE__,
 553                         "Invalid OS ABI \"%s\" passed to command handler.",
 554                         set_osabi_string);
 555     }
 556
 557   /* NOTE: At some point (true multiple architectures) we'll need to be more
 558      graceful here.  */
 559   gdbarch_info_init (&info);
 560   if (! gdbarch_update_p (info))
 561     internal_error (__FILE__, __LINE__, "Updating OS ABI failed.");
 562 }
 563
 564 static void
 565 show_osabi (char *args, int from_tty)
 566 {
 567   if (user_osabi_state == osabi_auto)
 568     printf_filtered ("The current OS ABI is \"auto\" (currently \"%s\").\n",
 569                      gdbarch_osabi_name (gdbarch_osabi (current_gdbarch)));
 570   else
 571     printf_filtered ("The current OS ABI is \"%s\".\n",
 572                      gdbarch_osabi_name (user_selected_osabi));
 573
 574   if (GDB_OSABI_DEFAULT != GDB_OSABI_UNKNOWN)
 575     printf_filtered ("The default OS ABI is \"%s\".\n",
 576                      gdbarch_osabi_name (GDB_OSABI_DEFAULT));
 577 }
 578 \f
 579 extern initialize_file_ftype _initialize_gdb_osabi; /* -Wmissing-prototype */
 580
 581 void
 582 _initialize_gdb_osabi (void)
 583 {
 584   struct cmd_list_element *c;
 585
 586   if (strcmp (gdb_osabi_names[GDB_OSABI_INVALID], "<invalid>") != 0)
 587     internal_error
 588       (__FILE__, __LINE__,
 589        "_initialize_gdb_osabi: gdb_osabi_names[] is inconsistent");
 590
 591   /* Register a generic sniffer for ELF flavoured files.  */
 592   gdbarch_register_osabi_sniffer (bfd_arch_unknown,
 593                                   bfd_target_elf_flavour,
 594                                   generic_elf_osabi_sniffer);
 595
 596   return;
 597
 598   /* Register the "set osabi" command.  */
 599   c = add_set_enum_cmd ("osabi", class_support, gdb_osabi_available_names,
 600                         &set_osabi_string, "Set OS ABI of target.", &setlist);
 601
 602   set_cmd_sfunc (c, set_osabi);
 603   add_cmd ("osabi", class_support, show_osabi, "Show OS/ABI of target.",
 604            &showlist);
 605   user_osabi_state = osabi_auto;
 606 }