ld/ldcref.c

   1 /* ldcref.c -- output a cross reference table
   2    Copyright 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004
   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., 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, 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_local_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    global 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_local_sym_xref);
 334 }
 335
 336 /* Check for prohibited cross references to local and section symbols.  */
 337
 338 static void
 339 check_local_sym_xref (lang_input_statement_type *statement)
 340 {
 341   bfd *abfd;
 342   lang_input_statement_type *li;
 343   asymbol **asymbols, **syms;
 344
 345   abfd = statement->the_bfd;
 346   if (abfd == NULL)
 347     return;
 348
 349   li = abfd->usrdata;
 350   if (li != NULL && li->asymbols != NULL)
 351     asymbols = li->asymbols;
 352   else
 353     {
 354       long symsize;
 355       long symbol_count;
 356
 357       symsize = bfd_get_symtab_upper_bound (abfd);
 358       if (symsize < 0)
 359         einfo (_("%B%F: could not read symbols; %E\n"), abfd);
 360       asymbols = xmalloc (symsize);
 361       symbol_count = bfd_canonicalize_symtab (abfd, asymbols);
 362       if (symbol_count < 0)
 363         einfo (_("%B%F: could not read symbols: %E\n"), abfd);
 364       if (li != NULL)
 365         {
 366           li->asymbols = asymbols;
 367           li->symbol_count = symbol_count;
 368         }
 369     }
 370
 371   for (syms = asymbols; *syms; ++syms)
 372     {
 373       asymbol *sym = *syms;
 374       if (sym->flags & (BSF_GLOBAL | BSF_WARNING | BSF_INDIRECT | BSF_FILE))
 375         continue;
 376       if ((sym->flags & (BSF_LOCAL | BSF_SECTION_SYM)) != 0
 377           && sym->section->output_section != NULL)
 378         {
 379           const char *outsecname, *symname;
 380           struct lang_nocrossrefs *ncrs;
 381           struct lang_nocrossref *ncr;
 382
 383           outsecname = sym->section->output_section->name;
 384           symname = NULL;
 385           if ((sym->flags & BSF_SECTION_SYM) == 0)
 386             symname = sym->name;
 387           for (ncrs = nocrossref_list; ncrs != NULL; ncrs = ncrs->next)
 388             for (ncr = ncrs->list; ncr != NULL; ncr = ncr->next)
 389               if (strcmp (ncr->name, outsecname) == 0)
 390                 check_refs (symname, sym->section, abfd, ncrs);
 391         }
 392     }
 393
 394   if (li == NULL)
 395     free (asymbols);
 396 }
 397
 398 /* Check one symbol to see if it is a prohibited cross reference.  */
 399
 400 static bfd_boolean
 401 check_nocrossref (struct cref_hash_entry *h, void *ignore ATTRIBUTE_UNUSED)
 402 {
 403   struct bfd_link_hash_entry *hl;
 404   asection *defsec;
 405   const char *defsecname;
 406   struct lang_nocrossrefs *ncrs;
 407   struct lang_nocrossref *ncr;
 408   struct cref_ref *ref;
 409
 410   hl = bfd_link_hash_lookup (link_info.hash, h->root.string, FALSE,
 411                              FALSE, TRUE);
 412   if (hl == NULL)
 413     {
 414       einfo (_("%P: symbol `%T' missing from main hash table\n"),
 415              h->root.string);
 416       return TRUE;
 417     }
 418
 419   if (hl->type != bfd_link_hash_defined
 420       && hl->type != bfd_link_hash_defweak)
 421     return TRUE;
 422
 423   defsec = hl->u.def.section->output_section;
 424   if (defsec == NULL)
 425     return TRUE;
 426   defsecname = bfd_get_section_name (defsec->owner, defsec);
 427
 428   for (ncrs = nocrossref_list; ncrs != NULL; ncrs = ncrs->next)
 429     for (ncr = ncrs->list; ncr != NULL; ncr = ncr->next)
 430       if (strcmp (ncr->name, defsecname) == 0)
 431         for (ref = h->refs; ref != NULL; ref = ref->next)
 432           check_refs (hl->root.string, hl->u.def.section, ref->abfd, ncrs);
 433
 434   return TRUE;
 435 }
 436
 437 /* The struct is used to pass information from check_refs to
 438    check_reloc_refs through bfd_map_over_sections.  */
 439
 440 struct check_refs_info {
 441   const char *sym_name;
 442   asection *defsec;
 443   struct lang_nocrossrefs *ncrs;
 444   asymbol **asymbols;
 445 };
 446
 447 /* This function is called for each symbol defined in a section which
 448    prohibits cross references.  We need to look through all references
 449    to this symbol, and ensure that the references are not from
 450    prohibited sections.  */
 451
 452 static void
 453 check_refs (const char *name,
 454             asection *sec,
 455             bfd *abfd,
 456             struct lang_nocrossrefs *ncrs)
 457 {
 458   lang_input_statement_type *li;
 459   asymbol **asymbols;
 460   struct check_refs_info info;
 461
 462   /* We need to look through the relocations for this BFD, to see
 463      if any of the relocations which refer to this symbol are from
 464      a prohibited section.  Note that we need to do this even for
 465      the BFD in which the symbol is defined, since even a single
 466      BFD might contain a prohibited cross reference.  */
 467
 468   li = abfd->usrdata;
 469   if (li != NULL && li->asymbols != NULL)
 470     asymbols = li->asymbols;
 471   else
 472     {
 473       long symsize;
 474       long symbol_count;
 475
 476       symsize = bfd_get_symtab_upper_bound (abfd);
 477       if (symsize < 0)
 478         einfo (_("%B%F: could not read symbols; %E\n"), abfd);
 479       asymbols = xmalloc (symsize);
 480       symbol_count = bfd_canonicalize_symtab (abfd, asymbols);
 481       if (symbol_count < 0)
 482         einfo (_("%B%F: could not read symbols: %E\n"), abfd);
 483       if (li != NULL)
 484         {
 485           li->asymbols = asymbols;
 486           li->symbol_count = symbol_count;
 487         }
 488     }
 489
 490   info.sym_name = name;
 491   info.defsec = sec;
 492   info.ncrs = ncrs;
 493   info.asymbols = asymbols;
 494   bfd_map_over_sections (abfd, check_reloc_refs, &info);
 495
 496   if (li == NULL)
 497     free (asymbols);
 498 }
 499
 500 /* This is called via bfd_map_over_sections.  INFO->SYM_NAME is a symbol
 501    defined in INFO->DEFSECNAME.  If this section maps into any of the
 502    sections listed in INFO->NCRS, other than INFO->DEFSECNAME, then we
 503    look through the relocations.  If any of the relocations are to
 504    INFO->SYM_NAME, then we report a prohibited cross reference error.  */
 505
 506 static void
 507 check_reloc_refs (bfd *abfd, asection *sec, void *iarg)
 508 {
 509   struct check_refs_info *info = iarg;
 510   asection *outsec;
 511   const char *outsecname;
 512   asection *outdefsec;
 513   const char *outdefsecname;
 514   struct lang_nocrossref *ncr;
 515   const char *symname;
 516   long relsize;
 517   arelent **relpp;
 518   long relcount;
 519   arelent **p, **pend;
 520
 521   outsec = sec->output_section;
 522   outsecname = bfd_get_section_name (outsec->owner, outsec);
 523
 524   outdefsec = info->defsec->output_section;
 525   outdefsecname = bfd_get_section_name (outdefsec->owner, outdefsec);
 526
 527   /* The section where the symbol is defined is permitted.  */
 528   if (strcmp (outsecname, outdefsecname) == 0)
 529     return;
 530
 531   for (ncr = info->ncrs->list; ncr != NULL; ncr = ncr->next)
 532     if (strcmp (outsecname, ncr->name) == 0)
 533       break;
 534
 535   if (ncr == NULL)
 536     return;
 537
 538   /* This section is one for which cross references are prohibited.
 539      Look through the relocations, and see if any of them are to
 540      INFO->SYM_NAME.  If INFO->SYMNAME is NULL, check for relocations
 541      against the section symbol.  */
 542
 543   symname = info->sym_name;
 544
 545   relsize = bfd_get_reloc_upper_bound (abfd, sec);
 546   if (relsize < 0)
 547     einfo (_("%B%F: could not read relocs: %E\n"), abfd);
 548   if (relsize == 0)
 549     return;
 550
 551   relpp = xmalloc (relsize);
 552   relcount = bfd_canonicalize_reloc (abfd, sec, relpp, info->asymbols);
 553   if (relcount < 0)
 554     einfo (_("%B%F: could not read relocs: %E\n"), abfd);
 555
 556   p = relpp;
 557   pend = p + relcount;
 558   for (; p < pend && *p != NULL; p++)
 559     {
 560       arelent *q = *p;
 561
 562       if (q->sym_ptr_ptr != NULL
 563           && *q->sym_ptr_ptr != NULL
 564           && (symname != NULL
 565               ? strcmp (bfd_asymbol_name (*q->sym_ptr_ptr), symname) == 0
 566               : (((*q->sym_ptr_ptr)->flags & BSF_SECTION_SYM) != 0
 567                  && bfd_get_section (*q->sym_ptr_ptr) == info->defsec)))
 568         {
 569           /* We found a reloc for the symbol.  The symbol is defined
 570              in OUTSECNAME.  This reloc is from a section which is
 571              mapped into a section from which references to OUTSECNAME
 572              are prohibited.  We must report an error.  */
 573           einfo (_("%X%C: prohibited cross reference from %s to `%T' in %s\n"),
 574                  abfd, sec, q->address, outsecname,
 575                  bfd_asymbol_name (*q->sym_ptr_ptr), outdefsecname);
 576         }
 577     }
 578
 579   free (relpp);
 580 }