gdb/somread.c

   1 /* Read HP PA/Risc object files for GDB.
   2    Copyright (C) 1991, 1992, 1994, 1995, 1996, 1998, 1999, 2000, 2001, 2002,
   3    2004, 2007 Free Software Foundation, Inc.
   4    Written by Fred Fish at Cygnus Support.
   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 2 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, write to the Free Software
  20    Foundation, Inc., 51 Franklin Street, Fifth Floor,
  21    Boston, MA 02110-1301, USA.  */
  22
  23 #include "defs.h"
  24 #include "bfd.h"
  25 #include <syms.h>
  26 #include "symtab.h"
  27 #include "symfile.h"
  28 #include "objfiles.h"
  29 #include "buildsym.h"
  30 #include "stabsread.h"
  31 #include "gdb-stabs.h"
  32 #include "complaints.h"
  33 #include "gdb_string.h"
  34 #include "demangle.h"
  35 #include "som.h"
  36 #include "libhppa.h"
  37
  38 #include "solib-som.h"
  39
  40 /*
  41
  42    LOCAL FUNCTION
  43
  44    som_symtab_read -- read the symbol table of a SOM file
  45
  46    SYNOPSIS
  47
  48    void som_symtab_read (bfd *abfd, struct objfile *objfile,
  49    struct section_offsets *section_offsets)
  50
  51    DESCRIPTION
  52
  53    Given an open bfd, a base address to relocate symbols to, and a
  54    flag that specifies whether or not this bfd is for an executable
  55    or not (may be shared library for example), add all the global
  56    function and data symbols to the minimal symbol table.
  57  */
  58
  59 static void
  60 som_symtab_read (bfd *abfd, struct objfile *objfile,
  61                  struct section_offsets *section_offsets)
  62 {
  63   unsigned int number_of_symbols;
  64   int val, dynamic;
  65   char *stringtab;
  66   asection *shlib_info;
  67   struct symbol_dictionary_record *buf, *bufp, *endbufp;
  68   char *symname;
  69   CONST int symsize = sizeof (struct symbol_dictionary_record);
  70   CORE_ADDR text_offset, data_offset;
  71
  72
  73   text_offset = ANOFFSET (section_offsets, 0);
  74   data_offset = ANOFFSET (section_offsets, 1);
  75
  76   number_of_symbols = bfd_get_symcount (abfd);
  77
  78   /* Allocate a buffer to read in the debug info.
  79      We avoid using alloca because the memory size could be so large
  80      that we could hit the stack size limit.  */
  81   buf = xmalloc (symsize * number_of_symbols);
  82   make_cleanup (xfree, buf);
  83   bfd_seek (abfd, obj_som_sym_filepos (abfd), SEEK_SET);
  84   val = bfd_bread (buf, symsize * number_of_symbols, abfd);
  85   if (val != symsize * number_of_symbols)
  86     error (_("Couldn't read symbol dictionary!"));
  87
  88   /* Allocate a buffer to read in the som stringtab section of
  89      the debugging info.  Again, we avoid using alloca because
  90      the data could be so large that we could potentially hit
  91      the stack size limitat.  */
  92   stringtab = xmalloc (obj_som_stringtab_size (abfd));
  93   make_cleanup (xfree, stringtab);
  94   bfd_seek (abfd, obj_som_str_filepos (abfd), SEEK_SET);
  95   val = bfd_bread (stringtab, obj_som_stringtab_size (abfd), abfd);
  96   if (val != obj_som_stringtab_size (abfd))
  97     error (_("Can't read in HP string table."));
  98
  99   /* We need to determine if objfile is a dynamic executable (so we
 100      can do the right thing for ST_ENTRY vs ST_CODE symbols).
 101
 102      There's nothing in the header which easily allows us to do
 103      this.
 104
 105      This code used to rely upon the existence of a $SHLIB_INFO$
 106      section to make this determination.  HP claims that it is
 107      more accurate to check for a nonzero text offset, but they
 108      have not provided any information about why that test is
 109      more accurate.  */
 110   dynamic = (text_offset != 0);
 111
 112   endbufp = buf + number_of_symbols;
 113   for (bufp = buf; bufp < endbufp; ++bufp)
 114     {
 115       enum minimal_symbol_type ms_type;
 116
 117       QUIT;
 118
 119       switch (bufp->symbol_scope)
 120         {
 121         case SS_UNIVERSAL:
 122         case SS_EXTERNAL:
 123           switch (bufp->symbol_type)
 124             {
 125             case ST_SYM_EXT:
 126             case ST_ARG_EXT:
 127               continue;
 128
 129             case ST_CODE:
 130             case ST_PRI_PROG:
 131             case ST_SEC_PROG:
 132             case ST_MILLICODE:
 133               symname = bufp->name.n_strx + stringtab;
 134               ms_type = mst_text;
 135               bufp->symbol_value += text_offset;
 136               bufp->symbol_value = gdbarch_smash_text_address
 137                                      (current_gdbarch, bufp->symbol_value);
 138               break;
 139
 140             case ST_ENTRY:
 141               symname = bufp->name.n_strx + stringtab;
 142               /* For a dynamic executable, ST_ENTRY symbols are
 143                  the stubs, while the ST_CODE symbol is the real
 144                  function.  */
 145               if (dynamic)
 146                 ms_type = mst_solib_trampoline;
 147               else
 148                 ms_type = mst_text;
 149               bufp->symbol_value += text_offset;
 150               bufp->symbol_value = gdbarch_smash_text_address
 151                                      (current_gdbarch, bufp->symbol_value);
 152               break;
 153
 154             case ST_STUB:
 155               symname = bufp->name.n_strx + stringtab;
 156               ms_type = mst_solib_trampoline;
 157               bufp->symbol_value += text_offset;
 158               bufp->symbol_value = gdbarch_smash_text_address
 159                                      (current_gdbarch, bufp->symbol_value);
 160               break;
 161
 162             case ST_DATA:
 163               symname = bufp->name.n_strx + stringtab;
 164               bufp->symbol_value += data_offset;
 165               ms_type = mst_data;
 166               break;
 167             default:
 168               continue;
 169             }
 170           break;
 171
 172 #if 0
 173           /* SS_GLOBAL and SS_LOCAL are two names for the same thing (!).  */
 174         case SS_GLOBAL:
 175 #endif
 176         case SS_LOCAL:
 177           switch (bufp->symbol_type)
 178             {
 179             case ST_SYM_EXT:
 180             case ST_ARG_EXT:
 181               continue;
 182
 183             case ST_CODE:
 184               symname = bufp->name.n_strx + stringtab;
 185               ms_type = mst_file_text;
 186               bufp->symbol_value += text_offset;
 187               bufp->symbol_value = gdbarch_smash_text_address
 188                                      (current_gdbarch, bufp->symbol_value);
 189
 190             check_strange_names:
 191               /* Utah GCC 2.5, FSF GCC 2.6 and later generate correct local
 192                  label prefixes for stabs, constant data, etc.  So we need
 193                  only filter out L$ symbols which are left in due to
 194                  limitations in how GAS generates SOM relocations.
 195
 196                  When linking in the HPUX C-library the HP linker has
 197                  the nasty habit of placing section symbols from the literal
 198                  subspaces in the middle of the program's text.  Filter
 199                  those out as best we can.  Check for first and last character
 200                  being '$'.
 201
 202                  And finally, the newer HP compilers emit crud like $PIC_foo$N
 203                  in some circumstance (PIC code I guess).  It's also claimed
 204                  that they emit D$ symbols too.  What stupidity.  */
 205               if ((symname[0] == 'L' && symname[1] == '$')
 206               || (symname[0] == '$' && symname[strlen (symname) - 1] == '$')
 207                   || (symname[0] == 'D' && symname[1] == '$')
 208                   || (strncmp (symname, "L0\001", 3) == 0)
 209                   || (strncmp (symname, "$PIC", 4) == 0))
 210                 continue;
 211               break;
 212
 213             case ST_PRI_PROG:
 214             case ST_SEC_PROG:
 215             case ST_MILLICODE:
 216               symname = bufp->name.n_strx + stringtab;
 217               ms_type = mst_file_text;
 218               bufp->symbol_value += text_offset;
 219               bufp->symbol_value = gdbarch_smash_text_address
 220                                      (current_gdbarch, bufp->symbol_value);
 221               break;
 222
 223             case ST_ENTRY:
 224               symname = bufp->name.n_strx + stringtab;
 225               /* SS_LOCAL symbols in a shared library do not have
 226                  export stubs, so we do not have to worry about
 227                  using mst_file_text vs mst_solib_trampoline here like
 228                  we do for SS_UNIVERSAL and SS_EXTERNAL symbols above.  */
 229               ms_type = mst_file_text;
 230               bufp->symbol_value += text_offset;
 231               bufp->symbol_value = gdbarch_smash_text_address
 232                                      (current_gdbarch, bufp->symbol_value);
 233               break;
 234
 235             case ST_STUB:
 236               symname = bufp->name.n_strx + stringtab;
 237               ms_type = mst_solib_trampoline;
 238               bufp->symbol_value += text_offset;
 239               bufp->symbol_value = gdbarch_smash_text_address
 240                                      (current_gdbarch, bufp->symbol_value);
 241               break;
 242
 243
 244             case ST_DATA:
 245               symname = bufp->name.n_strx + stringtab;
 246               bufp->symbol_value += data_offset;
 247               ms_type = mst_file_data;
 248               goto check_strange_names;
 249
 250             default:
 251               continue;
 252             }
 253           break;
 254
 255           /* This can happen for common symbols when -E is passed to the
 256              final link.  No idea _why_ that would make the linker force
 257              common symbols to have an SS_UNSAT scope, but it does.
 258
 259              This also happens for weak symbols, but their type is
 260              ST_DATA.  */
 261         case SS_UNSAT:
 262           switch (bufp->symbol_type)
 263             {
 264             case ST_STORAGE:
 265             case ST_DATA:
 266               symname = bufp->name.n_strx + stringtab;
 267               bufp->symbol_value += data_offset;
 268               ms_type = mst_data;
 269               break;
 270
 271             default:
 272               continue;
 273             }
 274           break;
 275
 276         default:
 277           continue;
 278         }
 279
 280       if (bufp->name.n_strx > obj_som_stringtab_size (abfd))
 281         error (_("Invalid symbol data; bad HP string table offset: %d"),
 282                bufp->name.n_strx);
 283
 284       prim_record_minimal_symbol (symname, bufp->symbol_value, ms_type,
 285                                   objfile);
 286     }
 287 }
 288
 289 /* Scan and build partial symbols for a symbol file.
 290    We have been initialized by a call to som_symfile_init, which
 291    currently does nothing.
 292
 293    SECTION_OFFSETS is a set of offsets to apply to relocate the symbols
 294    in each section.  This is ignored, as it isn't needed for SOM.
 295
 296    MAINLINE is true if we are reading the main symbol
 297    table (as opposed to a shared lib or dynamically loaded file).
 298
 299    This function only does the minimum work necessary for letting the
 300    user "name" things symbolically; it does not read the entire symtab.
 301    Instead, it reads the external and static symbols and puts them in partial
 302    symbol tables.  When more extensive information is requested of a
 303    file, the corresponding partial symbol table is mutated into a full
 304    fledged symbol table by going back and reading the symbols
 305    for real.
 306
 307    We look for sections with specific names, to tell us what debug
 308    format to look for:  FIXME!!!
 309
 310    somstab_build_psymtabs() handles STABS symbols.
 311
 312    Note that SOM files have a "minimal" symbol table, which is vaguely
 313    reminiscent of a COFF symbol table, but has only the minimal information
 314    necessary for linking.  We process this also, and use the information to
 315    build gdb's minimal symbol table.  This gives us some minimal debugging
 316    capability even for files compiled without -g.  */
 317
 318 static void
 319 som_symfile_read (struct objfile *objfile, int mainline)
 320 {
 321   bfd *abfd = objfile->obfd;
 322   struct cleanup *back_to;
 323
 324   init_minimal_symbol_collection ();
 325   back_to = make_cleanup_discard_minimal_symbols ();
 326
 327   /* Process the normal SOM symbol table first.
 328      This reads in the DNTT and string table, but doesn't
 329      actually scan the DNTT. It does scan the linker symbol
 330      table and thus build up a "minimal symbol table". */
 331
 332   som_symtab_read (abfd, objfile, objfile->section_offsets);
 333
 334   /* Install any minimal symbols that have been collected as the current
 335      minimal symbols for this objfile.
 336      Further symbol-reading is done incrementally, file-by-file,
 337      in a step known as "psymtab-to-symtab" expansion. hp-symtab-read.c
 338      contains the code to do the actual DNTT scanning and symtab building. */
 339   install_minimal_symbols (objfile);
 340   do_cleanups (back_to);
 341
 342   /* Now read information from the stabs debug sections.
 343      This is emitted by gcc.  */
 344   stabsect_build_psymtabs (objfile, mainline,
 345                            "$GDB_SYMBOLS$", "$GDB_STRINGS$", "$TEXT$");
 346 }
 347
 348 /* Initialize anything that needs initializing when a completely new symbol
 349    file is specified (not just adding some symbols from another file, e.g. a
 350    shared library).
 351
 352    We reinitialize buildsym, since we may be reading stabs from a SOM file.  */
 353
 354 static void
 355 som_new_init (struct objfile *ignore)
 356 {
 357   stabsread_new_init ();
 358   buildsym_new_init ();
 359 }
 360
 361 /* Perform any local cleanups required when we are done with a particular
 362    objfile.  I.E, we are in the process of discarding all symbol information
 363    for an objfile, freeing up all memory held for it, and unlinking the
 364    objfile struct from the global list of known objfiles. */
 365
 366 static void
 367 som_symfile_finish (struct objfile *objfile)
 368 {
 369   if (objfile->deprecated_sym_stab_info != NULL)
 370     {
 371       xfree (objfile->deprecated_sym_stab_info);
 372     }
 373 }
 374
 375 /* SOM specific initialization routine for reading symbols.  */
 376
 377 static void
 378 som_symfile_init (struct objfile *objfile)
 379 {
 380   /* SOM objects may be reordered, so set OBJF_REORDERED.  If we
 381      find this causes a significant slowdown in gdb then we could
 382      set it in the debug symbol readers only when necessary.  */
 383   objfile->flags |= OBJF_REORDERED;
 384 }
 385
 386 /* SOM specific parsing routine for section offsets.
 387
 388    Plain and simple for now.  */
 389
 390 static void
 391 som_symfile_offsets (struct objfile *objfile, struct section_addr_info *addrs)
 392 {
 393   int i;
 394   CORE_ADDR text_addr;
 395
 396   objfile->num_sections = bfd_count_sections (objfile->obfd);
 397   objfile->section_offsets = (struct section_offsets *)
 398     obstack_alloc (&objfile->objfile_obstack,
 399                    SIZEOF_N_SECTION_OFFSETS (objfile->num_sections));
 400
 401   /* FIXME: ezannoni 2000-04-20 The section names in SOM are not
 402      .text, .data, etc, but $TEXT$, $DATA$,... We should initialize
 403      SET_OFF_* from bfd. (See default_symfile_offsets()). But I don't
 404      know the correspondence between SOM sections and GDB's idea of
 405      section names. So for now we default to what is was before these
 406      changes.*/
 407   objfile->sect_index_text = 0;
 408   objfile->sect_index_data = 1;
 409   objfile->sect_index_bss = 2;
 410   objfile->sect_index_rodata = 3;
 411
 412   /* First see if we're a shared library.  If so, get the section
 413      offsets from the library, else get them from addrs.  */
 414   if (!som_solib_section_offsets (objfile, objfile->section_offsets))
 415     {
 416       /* Note: Here is OK to compare with ".text" because this is the
 417          name that gdb itself gives to that section, not the SOM
 418          name. */
 419       for (i = 0; i < addrs->num_sections && addrs->other[i].name; i++)
 420         if (strcmp (addrs->other[i].name, ".text") == 0)
 421           break;
 422       text_addr = addrs->other[i].addr;
 423
 424       for (i = 0; i < objfile->num_sections; i++)
 425         (objfile->section_offsets)->offsets[i] = text_addr;
 426     }
 427 }
 428 \f
 429
 430
 431 /* Register that we are able to handle SOM object file formats.  */
 432
 433 static struct sym_fns som_sym_fns =
 434 {
 435   bfd_target_som_flavour,
 436   som_new_init,                 /* sym_new_init: init anything gbl to entire symtab */
 437   som_symfile_init,             /* sym_init: read initial info, setup for sym_read() */
 438   som_symfile_read,             /* sym_read: read a symbol file into symtab */
 439   som_symfile_finish,           /* sym_finish: finished with file, cleanup */
 440   som_symfile_offsets,          /* sym_offsets:  Translate ext. to int. relocation */
 441   default_symfile_segments,     /* sym_segments: Get segment information from
 442                                    a file.  */
 443   NULL                          /* next: pointer to next struct sym_fns */
 444 };
 445
 446 void
 447 _initialize_somread (void)
 448 {
 449   add_symtab_fns (&som_sym_fns);
 450 }