ld/ldcref.c

   1 /* ldcref.c -- output a cross reference table
   2    Copyright 1996, 1997, 1998, 2000, 2002, 2003
   3    Free Software Foundation, Inc.
   4    Written by Ian Lance Taylor <ian@cygnus.com>
   5
   6 This file is part of GLD, the Gnu Linker.
   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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  21
  22 /* This file holds routines that manage the cross reference table.
  23    The table is used to generate cross reference reports.  It is also
  24    used to implement the NOCROSSREFS command in the linker script.  */
  25
  26 #include "bfd.h"
  27 #include "sysdep.h"
  28 #include "bfdlink.h"
  29 #include "libiberty.h"
  30
  31 #include "ld.h"
  32 #include "ldmain.h"
  33 #include "ldmisc.h"
  34 #include "ldexp.h"
  35 #include "ldlang.h"
  36
  37 /* We keep an instance of this structure for each reference to a
  38    symbol from a given object.  */
  39
  40 struct cref_ref {
  41   /* The next reference.  */
  42   struct cref_ref *next;
  43   /* The object.  */
  44   bfd *abfd;
  45   /* True if the symbol is defined.  */
  46   unsigned int def : 1;
  47   /* True if the symbol is common.  */
  48   unsigned int common : 1;
  49   /* True if the symbol is undefined.  */
  50   unsigned int undef : 1;
  51 };
  52
  53 /* We keep a hash table of symbols.  Each entry looks like this.  */
  54
  55 struct cref_hash_entry {
  56   struct bfd_hash_entry root;
  57   /* The demangled name.  */
  58   char *demangled;
  59   /* References to and definitions of this symbol.  */
  60   struct cref_ref *refs;
  61 };
  62
  63 /* This is what the hash table looks like.  */
  64
  65 struct cref_hash_table {
  66   struct bfd_hash_table root;
  67 };
  68
  69 /* Forward declarations.  */
  70
  71 static void output_one_cref (FILE *, struct cref_hash_entry *);
  72 static void check_section_sym_xref (lang_input_statement_type *);
  73 static bfd_boolean check_nocrossref (struct cref_hash_entry *, void *);
  74 static void check_refs (const char *, asection *, bfd *,
  75                         struct lang_nocrossrefs *);
  76 static void check_reloc_refs (bfd *, asection *, void *);
  77
  78 /* Look up an entry in the cref hash table.  */
  79
  80 #define cref_hash_lookup(table, string, create, copy)           \
  81   ((struct cref_hash_entry *)                                   \
  82    bfd_hash_lookup (&(table)->root, (string), (create), (copy)))
  83
  84 /* Traverse the cref hash table.  */
  85
  86 #define cref_hash_traverse(table, func, info)                           \
  87   (bfd_hash_traverse                                                    \
  88    (&(table)->root,                                                     \
  89     (bfd_boolean (*) (struct bfd_hash_entry *, void *)) (func),         \
  90     (info)))
  91
  92 /* The cref hash table.  */
  93
  94 static struct cref_hash_table cref_table;
  95
  96 /* Whether the cref hash table has been initialized.  */
  97
  98 static bfd_boolean cref_initialized;
  99
 100 /* The number of symbols seen so far.  */
 101
 102 static size_t cref_symcount;
 103
 104 /* Create an entry in a cref hash table.  */
 105
 106 static struct bfd_hash_entry *
 107 cref_hash_newfunc (struct bfd_hash_entry *entry,
 108                    struct bfd_hash_table *table,
 109                    const char *string)
 110 {
 111   struct cref_hash_entry *ret = (struct cref_hash_entry *) entry;
 112
 113   /* Allocate the structure if it has not already been allocated by a
 114      subclass.  */
 115   if (ret == NULL)
 116     ret = ((struct cref_hash_entry *)
 117            bfd_hash_allocate (table, sizeof (struct cref_hash_entry)));
 118   if (ret == NULL)
 119     return NULL;
 120
 121   /* Call the allocation method of the superclass.  */
 122   ret = ((struct cref_hash_entry *)
 123          bfd_hash_newfunc ((struct bfd_hash_entry *) ret, table, string));
 124   if (ret != NULL)
 125     {
 126       /* Set local fields.  */
 127       ret->demangled = NULL;
 128       ret->refs = NULL;
 129
 130       /* Keep a count of the number of entries created in the hash
 131          table.  */
 132       ++cref_symcount;
 133     }
 134
 135   return &ret->root;
 136 }
 137
 138 /* Add a symbol to the cref hash table.  This is called for every
 139    symbol that is seen during the link.  */
 140
 141 void
 142 add_cref (const char *name,
 143           bfd *abfd,
 144           asection *section,
 145           bfd_vma value ATTRIBUTE_UNUSED)
 146 {
 147   struct cref_hash_entry *h;
 148   struct cref_ref *r;
 149
 150   if (! cref_initialized)
 151     {
 152       if (! bfd_hash_table_init (&cref_table.root, cref_hash_newfunc))
 153         einfo (_("%X%P: bfd_hash_table_init of cref table failed: %E\n"));
 154       cref_initialized = TRUE;
 155     }
 156
 157   h = cref_hash_lookup (&cref_table, name, TRUE, FALSE);
 158   if (h == NULL)
 159     einfo (_("%X%P: cref_hash_lookup failed: %E\n"));
 160
 161   for (r = h->refs; r != NULL; r = r->next)
 162     if (r->abfd == abfd)
 163       break;
 164
 165   if (r == NULL)
 166     {
 167       r = xmalloc (sizeof *r);
 168       r->next = h->refs;
 169       h->refs = r;
 170       r->abfd = abfd;
 171       r->def = FALSE;
 172       r->common = FALSE;
 173       r->undef = FALSE;
 174     }
 175
 176   if (bfd_is_und_section (section))
 177     r->undef = TRUE;
 178   else if (bfd_is_com_section (section))
 179     r->common = TRUE;
 180   else
 181     r->def = TRUE;
 182 }
 183
 184 /* Copy the addresses of the hash table entries into an array.  This
 185    is called via cref_hash_traverse.  We also fill in the demangled
 186    name.  */
 187
 188 static bfd_boolean
 189 cref_fill_array (struct cref_hash_entry *h, void *data)
 190 {
 191   struct cref_hash_entry ***pph = data;
 192
 193   ASSERT (h->demangled == NULL);
 194   h->demangled = demangle (h->root.string);
 195
 196   **pph = h;
 197
 198   ++*pph;
 199
 200   return TRUE;
 201 }
 202
 203 /* Sort an array of cref hash table entries by name.  */
 204
 205 static int
 206 cref_sort_array (const void *a1, const void *a2)
 207 {
 208   const struct cref_hash_entry * const *p1 = a1;
 209   const struct cref_hash_entry * const *p2 = a2;
 210
 211   return strcmp ((*p1)->demangled, (*p2)->demangled);
 212 }
 213
 214 /* Write out the cref table.  */
 215
 216 #define FILECOL (50)
 217
 218 void
 219 output_cref (FILE *fp)
 220 {
 221   int len;
 222   struct cref_hash_entry **csyms, **csym_fill, **csym, **csym_end;
 223   const char *msg;
 224
 225   fprintf (fp, _("\nCross Reference Table\n\n"));
 226   msg = _("Symbol");
 227   fprintf (fp, "%s", msg);
 228   len = strlen (msg);
 229   while (len < FILECOL)
 230     {
 231       putc (' ', fp);
 232       ++len;
 233     }
 234   fprintf (fp, _("File\n"));
 235
 236   if (! cref_initialized)
 237     {
 238       fprintf (fp, _("No symbols\n"));
 239       return;
 240     }
 241
 242   csyms = xmalloc (cref_symcount * sizeof (*csyms));
 243
 244   csym_fill = csyms;
 245   cref_hash_traverse (&cref_table, cref_fill_array, &csym_fill);
 246   ASSERT ((size_t) (csym_fill - csyms) == cref_symcount);
 247
 248   qsort (csyms, cref_symcount, sizeof (*csyms), cref_sort_array);
 249
 250   csym_end = csyms + cref_symcount;
 251   for (csym = csyms; csym < csym_end; csym++)
 252     output_one_cref (fp, *csym);
 253 }
 254
 255 /* Output one entry in the cross reference table.  */
 256
 257 static void
 258 output_one_cref (FILE *fp, struct cref_hash_entry *h)
 259 {
 260   int len;
 261   struct bfd_link_hash_entry *hl;
 262   struct cref_ref *r;
 263
 264   hl = bfd_link_hash_lookup (link_info.hash, h->root.string, FALSE,
 265                              FALSE, TRUE);
 266   if (hl == NULL)
 267     einfo ("%P: symbol `%T' missing from main hash table\n",
 268            h->root.string);
 269   else
 270     {
 271       /* If this symbol is defined in a dynamic object but never
 272          referenced by a normal object, then don't print it.  */
 273       if (hl->type == bfd_link_hash_defined)
 274         {
 275           if (hl->u.def.section->output_section == NULL)
 276             return;
 277           if (hl->u.def.section->owner != NULL
 278               && (hl->u.def.section->owner->flags & DYNAMIC) != 0)
 279             {
 280               for (r = h->refs; r != NULL; r = r->next)
 281                 if ((r->abfd->flags & DYNAMIC) == 0)
 282                   break;
 283               if (r == NULL)
 284                 return;
 285             }
 286         }
 287     }
 288
 289   fprintf (fp, "%s ", h->demangled);
 290   len = strlen (h->demangled) + 1;
 291
 292   for (r = h->refs; r != NULL; r = r->next)
 293     {
 294       if (r->def)
 295         {
 296           while (len < FILECOL)
 297             {
 298               putc (' ', fp);
 299               ++len;
 300             }
 301           lfinfo (fp, "%B\n", r->abfd);
 302           len = 0;
 303         }
 304     }
 305
 306   for (r = h->refs; r != NULL; r = r->next)
 307     {
 308       if (! r->def)
 309         {
 310           while (len < FILECOL)
 311             {
 312               putc (' ', fp);
 313               ++len;
 314             }
 315           lfinfo (fp, "%B\n", r->abfd);
 316           len = 0;
 317         }
 318     }
 319
 320   ASSERT (len == 0);
 321 }
 322
 323 /* Check for prohibited cross references.  */
 324
 325 void
 326 check_nocrossrefs (void)
 327 {
 328   if (! cref_initialized)
 329     return;
 330
 331   cref_hash_traverse (&cref_table, check_nocrossref, NULL);
 332
 333   lang_for_each_file (check_section_sym_xref);
 334 }
 335
 336 /* Checks for prohibited cross references to section symbols.  */
 337
 338 static void
 339 check_section_sym_xref (lang_input_statement_type *statement)
 340 {
 341   bfd *abfd;
 342   asection *sec;
 343
 344   abfd = statement->the_bfd;
 345   if (abfd == NULL)
 346     return;
 347
 348   for (sec = abfd->sections; sec != NULL; sec = sec->next)
 349     {
 350       asection *outsec;
 351
 352       outsec = sec->output_section;
 353       if (outsec != NULL)
 354         {
 355           const char *outsecname;
 356           struct lang_nocrossrefs *ncrs;
 357           struct lang_nocrossref *ncr;
 358
 359           outsecname = outsec->name;
 360           for (ncrs = nocrossref_list; ncrs != NULL; ncrs = ncrs->next)
 361             for (ncr = ncrs->list; ncr != NULL; ncr = ncr->next)
 362               if (strcmp (ncr->name, outsecname) == 0)
 363                 check_refs (NULL, sec, abfd, ncrs);
 364         }
 365     }
 366 }
 367
 368 /* Check one symbol to see if it is a prohibited cross reference.  */
 369
 370 static bfd_boolean
 371 check_nocrossref (struct cref_hash_entry *h, void *ignore ATTRIBUTE_UNUSED)
 372 {
 373   struct bfd_link_hash_entry *hl;
 374   asection *defsec;
 375   const char *defsecname;
 376   struct lang_nocrossrefs *ncrs;
 377   struct lang_nocrossref *ncr;
 378   struct cref_ref *ref;
 379
 380   hl = bfd_link_hash_lookup (link_info.hash, h->root.string, FALSE,
 381                              FALSE, TRUE);
 382   if (hl == NULL)
 383     {
 384       einfo (_("%P: symbol `%T' missing from main hash table\n"),
 385              h->root.string);
 386       return TRUE;
 387     }
 388
 389   if (hl->type != bfd_link_hash_defined
 390       && hl->type != bfd_link_hash_defweak)
 391     return TRUE;
 392
 393   defsec = hl->u.def.section->output_section;
 394   if (defsec == NULL)
 395     return TRUE;
 396   defsecname = bfd_get_section_name (defsec->owner, defsec);
 397
 398   for (ncrs = nocrossref_list; ncrs != NULL; ncrs = ncrs->next)
 399     for (ncr = ncrs->list; ncr != NULL; ncr = ncr->next)
 400       if (strcmp (ncr->name, defsecname) == 0)
 401         for (ref = h->refs; ref != NULL; ref = ref->next)
 402           check_refs (hl->root.string, hl->u.def.section, ref->abfd, ncrs);
 403
 404   return TRUE;
 405 }
 406
 407 /* The struct is used to pass information from check_refs to
 408    check_reloc_refs through bfd_map_over_sections.  */
 409
 410 struct check_refs_info {
 411   const char *sym_name;
 412   asection *defsec;
 413   struct lang_nocrossrefs *ncrs;
 414   asymbol **asymbols;
 415 };
 416
 417 /* This function is called for each symbol defined in a section which
 418    prohibits cross references.  We need to look through all references
 419    to this symbol, and ensure that the references are not from
 420    prohibited sections.  */
 421
 422 static void
 423 check_refs (const char *name,
 424             asection *sec,
 425             bfd *abfd,
 426             struct lang_nocrossrefs *ncrs)
 427 {
 428   lang_input_statement_type *li;
 429   asymbol **asymbols;
 430   struct check_refs_info info;
 431
 432   /* We need to look through the relocations for this BFD, to see
 433      if any of the relocations which refer to this symbol are from
 434      a prohibited section.  Note that we need to do this even for
 435      the BFD in which the symbol is defined, since even a single
 436      BFD might contain a prohibited cross reference.  */
 437
 438   li = abfd->usrdata;
 439   if (li != NULL && li->asymbols != NULL)
 440     asymbols = li->asymbols;
 441   else
 442     {
 443       long symsize;
 444       long symbol_count;
 445
 446       symsize = bfd_get_symtab_upper_bound (abfd);
 447       if (symsize < 0)
 448         einfo (_("%B%F: could not read symbols; %E\n"), abfd);
 449       asymbols = xmalloc (symsize);
 450       symbol_count = bfd_canonicalize_symtab (abfd, asymbols);
 451       if (symbol_count < 0)
 452         einfo (_("%B%F: could not read symbols: %E\n"), abfd);
 453       if (li != NULL)
 454         {
 455           li->asymbols = asymbols;
 456           li->symbol_count = symbol_count;
 457         }
 458     }
 459
 460   info.sym_name = name;
 461   info.defsec = sec;
 462   info.ncrs = ncrs;
 463   info.asymbols = asymbols;
 464   bfd_map_over_sections (abfd, check_reloc_refs, &info);
 465
 466   if (li == NULL)
 467     free (asymbols);
 468 }
 469
 470 /* This is called via bfd_map_over_sections.  INFO->SYM_NAME is a symbol
 471    defined in INFO->DEFSECNAME.  If this section maps into any of the
 472    sections listed in INFO->NCRS, other than INFO->DEFSECNAME, then we
 473    look through the relocations.  If any of the relocations are to
 474    INFO->SYM_NAME, then we report a prohibited cross reference error.  */
 475
 476 static void
 477 check_reloc_refs (bfd *abfd, asection *sec, void *iarg)
 478 {
 479   struct check_refs_info *info = iarg;
 480   asection *outsec;
 481   const char *outsecname;
 482   asection *outdefsec;
 483   const char *outdefsecname;
 484   struct lang_nocrossref *ncr;
 485   const char *symname;
 486   long relsize;
 487   arelent **relpp;
 488   long relcount;
 489   arelent **p, **pend;
 490
 491   outsec = sec->output_section;
 492   outsecname = bfd_get_section_name (outsec->owner, outsec);
 493
 494   outdefsec = info->defsec->output_section;
 495   outdefsecname = bfd_get_section_name (outdefsec->owner, outdefsec);
 496
 497   /* The section where the symbol is defined is permitted.  */
 498   if (strcmp (outsecname, outdefsecname) == 0)
 499     return;
 500
 501   for (ncr = info->ncrs->list; ncr != NULL; ncr = ncr->next)
 502     if (strcmp (outsecname, ncr->name) == 0)
 503       break;
 504
 505   if (ncr == NULL)
 506     return;
 507
 508   /* This section is one for which cross references are prohibited.
 509      Look through the relocations, and see if any of them are to
 510      INFO->SYM_NAME.  If INFO->SYMNAME is NULL, check for relocations
 511      against the section symbol.  */
 512
 513   symname = info->sym_name;
 514
 515   relsize = bfd_get_reloc_upper_bound (abfd, sec);
 516   if (relsize < 0)
 517     einfo (_("%B%F: could not read relocs: %E\n"), abfd);
 518   if (relsize == 0)
 519     return;
 520
 521   relpp = xmalloc (relsize);
 522   relcount = bfd_canonicalize_reloc (abfd, sec, relpp, info->asymbols);
 523   if (relcount < 0)
 524     einfo (_("%B%F: could not read relocs: %E\n"), abfd);
 525
 526   p = relpp;
 527   pend = p + relcount;
 528   for (; p < pend && *p != NULL; p++)
 529     {
 530       arelent *q = *p;
 531
 532       if (q->sym_ptr_ptr != NULL
 533           && *q->sym_ptr_ptr != NULL
 534           && (symname != NULL
 535               ? strcmp (bfd_asymbol_name (*q->sym_ptr_ptr), symname) == 0
 536               : (((*q->sym_ptr_ptr)->flags & BSF_SECTION_SYM) != 0
 537                  && bfd_get_section (*q->sym_ptr_ptr) == info->defsec)))
 538         {
 539           /* We found a reloc for the symbol.  The symbol is defined
 540              in OUTSECNAME.  This reloc is from a section which is
 541              mapped into a section from which references to OUTSECNAME
 542              are prohibited.  We must report an error.  */
 543           einfo (_("%X%C: prohibited cross reference from %s to `%T' in %s\n"),
 544                  abfd, sec, q->address, outsecname,
 545                  bfd_asymbol_name (*q->sym_ptr_ptr), outdefsecname);
 546         }
 547     }
 548
 549   free (relpp);
 550 }