ld/ldcref.c

   1 /* ldcref.c -- output a cross reference table
   2    Copyright (C) 1996, 97, 98, 99, 2000 Free Software Foundation, Inc.
   3    Written by Ian Lance Taylor <ian@cygnus.com>
   4
   5 This file is part of GLD, the Gnu Linker.
   6
   7 This program is free software; you can redistribute it and/or modify
   8 it under the terms of the GNU General Public License as published by
   9 the Free Software Foundation; either version 2 of the License, or
  10 (at your option) any later version.
  11
  12 This program is distributed in the hope that it will be useful,
  13 but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 GNU General Public License for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with this program; if not, write to the Free Software
  19 Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  20
  21 /* This file holds routines that manage the cross reference table.
  22    The table is used to generate cross reference reports.  It is also
  23    used to implement the NOCROSSREFS command in the linker script.  */
  24
  25 #include "bfd.h"
  26 #include "sysdep.h"
  27 #include "bfdlink.h"
  28 #include "libiberty.h"
  29
  30 #include "ld.h"
  31 #include "ldmain.h"
  32 #include "ldmisc.h"
  33 #include "ldexp.h"
  34 #include "ldlang.h"
  35
  36 /* We keep an instance of this structure for each reference to a
  37    symbol from a given object.  */
  38
  39 struct cref_ref
  40 {
  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 {
  57   struct bfd_hash_entry root;
  58   /* The demangled name.  */
  59   char *demangled;
  60   /* References to and definitions of this symbol.  */
  61   struct cref_ref *refs;
  62 };
  63
  64 /* This is what the hash table looks like.  */
  65
  66 struct cref_hash_table
  67 {
  68   struct bfd_hash_table root;
  69 };
  70
  71 /* Local functions.  */
  72
  73 static struct bfd_hash_entry *cref_hash_newfunc
  74   PARAMS ((struct bfd_hash_entry *, struct bfd_hash_table *, const char *));
  75 static boolean cref_fill_array PARAMS ((struct cref_hash_entry *, PTR));
  76 static int cref_sort_array PARAMS ((const PTR, const PTR));
  77 static void output_one_cref PARAMS ((FILE *, struct cref_hash_entry *));
  78 static boolean check_nocrossref PARAMS ((struct cref_hash_entry *, PTR));
  79 static void check_refs
  80   PARAMS ((struct cref_hash_entry *, struct bfd_link_hash_entry *,
  81            struct lang_nocrossrefs *));
  82 static void check_reloc_refs PARAMS ((bfd *, asection *, PTR));
  83
  84 /* Look up an entry in the cref hash table.  */
  85
  86 #define cref_hash_lookup(table, string, create, copy)           \
  87   ((struct cref_hash_entry *)                                   \
  88    bfd_hash_lookup (&(table)->root, (string), (create), (copy)))
  89
  90 /* Traverse the cref hash table.  */
  91
  92 #define cref_hash_traverse(table, func, info)                           \
  93   (bfd_hash_traverse                                                    \
  94    (&(table)->root,                                                     \
  95     (boolean (*) PARAMS ((struct bfd_hash_entry *, PTR))) (func),       \
  96     (info)))
  97
  98 /* The cref hash table.  */
  99
 100 static struct cref_hash_table cref_table;
 101
 102 /* Whether the cref hash table has been initialized.  */
 103
 104 static boolean cref_initialized;
 105
 106 /* The number of symbols seen so far.  */
 107
 108 static size_t cref_symcount;
 109
 110 /* Create an entry in a cref hash table.  */
 111
 112 static struct bfd_hash_entry *
 113 cref_hash_newfunc (entry, table, string)
 114      struct bfd_hash_entry *entry;
 115      struct bfd_hash_table *table;
 116      const char *string;
 117 {
 118   struct cref_hash_entry *ret = (struct cref_hash_entry *) entry;
 119
 120   /* Allocate the structure if it has not already been allocated by a
 121      subclass.  */
 122   if (ret == NULL)
 123     ret = ((struct cref_hash_entry *)
 124            bfd_hash_allocate (table, sizeof (struct cref_hash_entry)));
 125   if (ret == NULL)
 126     return (struct bfd_hash_entry *) ret;
 127
 128   /* Call the allocation method of the superclass.  */
 129   ret = ((struct cref_hash_entry *)
 130          bfd_hash_newfunc ((struct bfd_hash_entry *) ret, table, string));
 131   if (ret != NULL)
 132     {
 133       /* Set local fields.  */
 134       ret->demangled = NULL;
 135       ret->refs = NULL;
 136
 137       /* Keep a count of the number of entries created in the hash
 138          table.  */
 139       ++cref_symcount;
 140     }
 141
 142   return (struct bfd_hash_entry *) ret;
 143 }
 144
 145 /* Add a symbol to the cref hash table.  This is called for every
 146    symbol that is seen during the link.  */
 147
 148 /*ARGSUSED*/
 149 void
 150 add_cref (name, abfd, section, value)
 151      const char *name;
 152      bfd *abfd;
 153      asection *section;
 154      bfd_vma value ATTRIBUTE_UNUSED;
 155 {
 156   struct cref_hash_entry *h;
 157   struct cref_ref *r;
 158
 159   if (! cref_initialized)
 160     {
 161       if (! bfd_hash_table_init (&cref_table.root, cref_hash_newfunc))
 162         einfo (_("%X%P: bfd_hash_table_init of cref table failed: %E\n"));
 163       cref_initialized = true;
 164     }
 165
 166   h = cref_hash_lookup (&cref_table, name, true, false);
 167   if (h == NULL)
 168     einfo (_("%X%P: cref_hash_lookup failed: %E\n"));
 169
 170   for (r = h->refs; r != NULL; r = r->next)
 171     if (r->abfd == abfd)
 172       break;
 173
 174   if (r == NULL)
 175     {
 176       r = (struct cref_ref *) xmalloc (sizeof *r);
 177       r->next = h->refs;
 178       h->refs = r;
 179       r->abfd = abfd;
 180       r->def = false;
 181       r->common = false;
 182       r->undef = false;
 183     }
 184
 185   if (bfd_is_und_section (section))
 186     r->undef = true;
 187   else if (bfd_is_com_section (section))
 188     r->common = true;
 189   else
 190     r->def = true;
 191 }
 192
 193 /* Copy the addresses of the hash table entries into an array.  This
 194    is called via cref_hash_traverse.  We also fill in the demangled
 195    name.  */
 196
 197 static boolean
 198 cref_fill_array (h, data)
 199      struct cref_hash_entry *h;
 200      PTR data;
 201 {
 202   struct cref_hash_entry ***pph = (struct cref_hash_entry ***) data;
 203
 204   ASSERT (h->demangled == NULL);
 205   h->demangled = demangle (h->root.string);
 206
 207   **pph = h;
 208
 209   ++*pph;
 210
 211   return true;
 212 }
 213
 214 /* Sort an array of cref hash table entries by name.  */
 215
 216 static int
 217 cref_sort_array (a1, a2)
 218      const PTR a1;
 219      const PTR a2;
 220 {
 221   const struct cref_hash_entry **p1 = (const struct cref_hash_entry **) a1;
 222   const struct cref_hash_entry **p2 = (const struct cref_hash_entry **) a2;
 223
 224   return strcmp ((*p1)->demangled, (*p2)->demangled);
 225 }
 226
 227 /* Write out the cref table.  */
 228
 229 #define FILECOL (50)
 230
 231 void
 232 output_cref (fp)
 233      FILE *fp;
 234 {
 235   int len;
 236   struct cref_hash_entry **csyms, **csym_fill, **csym, **csym_end;
 237   const char *msg;
 238
 239   fprintf (fp, _("\nCross Reference Table\n\n"));
 240   msg = _("Symbol");
 241   fprintf (fp, "%s", msg);
 242   len = strlen (msg);
 243   while (len < FILECOL)
 244     {
 245       putc (' ' , fp);
 246       ++len;
 247     }
 248   fprintf (fp, _("File\n"));
 249
 250   if (! cref_initialized)
 251     {
 252       fprintf (fp, _("No symbols\n"));
 253       return;
 254     }
 255
 256   csyms = ((struct cref_hash_entry **)
 257            xmalloc (cref_symcount * sizeof (*csyms)));
 258
 259   csym_fill = csyms;
 260   cref_hash_traverse (&cref_table, cref_fill_array, &csym_fill);
 261   ASSERT ((size_t) (csym_fill - csyms) == cref_symcount);
 262
 263   qsort (csyms, cref_symcount, sizeof (*csyms), cref_sort_array);
 264
 265   csym_end = csyms + cref_symcount;
 266   for (csym = csyms; csym < csym_end; csym++)
 267     output_one_cref (fp, *csym);
 268 }
 269
 270 /* Output one entry in the cross reference table.  */
 271
 272 static void
 273 output_one_cref (fp, h)
 274      FILE *fp;
 275      struct cref_hash_entry *h;
 276 {
 277   int len;
 278   struct bfd_link_hash_entry *hl;
 279   struct cref_ref *r;
 280
 281   hl = bfd_link_hash_lookup (link_info.hash, h->root.string, false,
 282                              false, true);
 283   if (hl == NULL)
 284     einfo ("%P: symbol `%T' missing from main hash table\n",
 285            h->root.string);
 286   else
 287     {
 288       /* If this symbol is defined in a dynamic object but never
 289          referenced by a normal object, then don't print it.  */
 290       if (hl->type == bfd_link_hash_defined)
 291         {
 292           if (hl->u.def.section->output_section == NULL)
 293             return;
 294           if (hl->u.def.section->owner != NULL
 295               && (hl->u.def.section->owner->flags & DYNAMIC) != 0)
 296             {
 297               for (r = h->refs; r != NULL; r = r->next)
 298                 if ((r->abfd->flags & DYNAMIC) == 0)
 299                   break;
 300               if (r == NULL)
 301                 return;
 302             }
 303         }
 304     }
 305
 306   fprintf (fp, "%s ", h->demangled);
 307   len = strlen (h->demangled) + 1;
 308
 309   for (r = h->refs; r != NULL; r = r->next)
 310     {
 311       if (r->def)
 312         {
 313           while (len < FILECOL)
 314             {
 315               putc (' ', fp);
 316               ++len;
 317             }
 318           lfinfo (fp, "%B\n", r->abfd);
 319           len = 0;
 320         }
 321     }
 322
 323   for (r = h->refs; r != NULL; r = r->next)
 324     {
 325       if (! r->def)
 326         {
 327           while (len < FILECOL)
 328             {
 329               putc (' ', fp);
 330               ++len;
 331             }
 332           lfinfo (fp, "%B\n", r->abfd);
 333           len = 0;
 334         }
 335     }
 336
 337   ASSERT (len == 0);
 338 }
 339
 340 /* Check for prohibited cross references.  */
 341
 342 void
 343 check_nocrossrefs ()
 344 {
 345   if (! cref_initialized)
 346     return;
 347
 348   cref_hash_traverse (&cref_table, check_nocrossref, (PTR) NULL);
 349 }
 350
 351 /* Check one symbol to see if it is a prohibited cross reference.  */
 352
 353 /*ARGSUSED*/
 354 static boolean
 355 check_nocrossref (h, ignore)
 356      struct cref_hash_entry *h;
 357      PTR ignore ATTRIBUTE_UNUSED;
 358 {
 359   struct bfd_link_hash_entry *hl;
 360   asection *defsec;
 361   const char *defsecname;
 362   struct lang_nocrossrefs *ncrs;
 363   struct lang_nocrossref *ncr;
 364
 365   hl = bfd_link_hash_lookup (link_info.hash, h->root.string, false,
 366                              false, true);
 367   if (hl == NULL)
 368     {
 369       einfo (_("%P: symbol `%T' missing from main hash table\n"),
 370              h->root.string);
 371       return true;
 372     }
 373
 374   if (hl->type != bfd_link_hash_defined
 375       && hl->type != bfd_link_hash_defweak)
 376     return true;
 377
 378   defsec = hl->u.def.section->output_section;
 379   if (defsec == NULL)
 380     return true;
 381   defsecname = bfd_get_section_name (defsec->owner, defsec);
 382
 383   for (ncrs = nocrossref_list; ncrs != NULL; ncrs = ncrs->next)
 384     for (ncr = ncrs->list; ncr != NULL; ncr = ncr->next)
 385       if (strcmp (ncr->name, defsecname) == 0)
 386         check_refs (h, hl, ncrs);
 387
 388   return true;
 389 }
 390
 391 /* The struct is used to pass information from check_refs to
 392    check_reloc_refs through bfd_map_over_sections.  */
 393
 394 struct check_refs_info
 395 {
 396   struct cref_hash_entry *h;
 397   asection *defsec;
 398   struct lang_nocrossrefs *ncrs;
 399   asymbol **asymbols;
 400   boolean same;
 401 };
 402
 403 /* This function is called for each symbol defined in a section which
 404    prohibits cross references.  We need to look through all references
 405    to this symbol, and ensure that the references are not from
 406    prohibited sections.  */
 407
 408 static void
 409 check_refs (h, hl, ncrs)
 410      struct cref_hash_entry *h;
 411      struct bfd_link_hash_entry *hl;
 412      struct lang_nocrossrefs *ncrs;
 413 {
 414   struct cref_ref *ref;
 415
 416   for (ref = h->refs; ref != NULL; ref = ref->next)
 417     {
 418       lang_input_statement_type *li;
 419       asymbol **asymbols;
 420       struct check_refs_info info;
 421
 422       /* We need to look through the relocations for this BFD, to see
 423          if any of the relocations which refer to this symbol are from
 424          a prohibited section.  Note that we need to do this even for
 425          the BFD in which the symbol is defined, since even a single
 426          BFD might contain a prohibited cross reference; for this
 427          case, we set the SAME field in INFO, which will cause
 428          CHECK_RELOCS_REFS to check for relocations against the
 429          section as well as against the symbol.  */
 430
 431       li = (lang_input_statement_type *) ref->abfd->usrdata;
 432       if (li != NULL && li->asymbols != NULL)
 433         asymbols = li->asymbols;
 434       else
 435         {
 436           long symsize;
 437           long symbol_count;
 438
 439           symsize = bfd_get_symtab_upper_bound (ref->abfd);
 440           if (symsize < 0)
 441             einfo (_("%B%F: could not read symbols; %E\n"), ref->abfd);
 442           asymbols = (asymbol **) xmalloc (symsize);
 443           symbol_count = bfd_canonicalize_symtab (ref->abfd, asymbols);
 444           if (symbol_count < 0)
 445             einfo (_("%B%F: could not read symbols: %E\n"), ref->abfd);
 446           if (li != NULL)
 447             {
 448               li->asymbols = asymbols;
 449               li->symbol_count = symbol_count;
 450             }
 451         }
 452
 453       info.h = h;
 454       info.defsec = hl->u.def.section;
 455       info.ncrs = ncrs;
 456       info.asymbols = asymbols;
 457       if (ref->abfd == hl->u.def.section->owner)
 458         info.same = true;
 459       else
 460         info.same = false;
 461       bfd_map_over_sections (ref->abfd, check_reloc_refs, (PTR) &info);
 462
 463       if (li == NULL)
 464         free (asymbols);
 465     }
 466 }
 467
 468 /* This is called via bfd_map_over_sections.  INFO->H is a symbol
 469    defined in INFO->DEFSECNAME.  If this section maps into any of the
 470    sections listed in INFO->NCRS, other than INFO->DEFSECNAME, then we
 471    look through the relocations.  If any of the relocations are to
 472    INFO->H, then we report a prohibited cross reference error.  */
 473
 474 static void
 475 check_reloc_refs (abfd, sec, iarg)
 476      bfd *abfd;
 477      asection *sec;
 478      PTR iarg;
 479 {
 480   struct check_refs_info *info = (struct check_refs_info *) iarg;
 481   asection *outsec;
 482   const char *outsecname;
 483   asection *outdefsec;
 484   const char *outdefsecname;
 485   struct lang_nocrossref *ncr;
 486   const char *symname;
 487   long relsize;
 488   arelent **relpp;
 489   long relcount;
 490   arelent **p, **pend;
 491
 492   outsec = sec->output_section;
 493   outsecname = bfd_get_section_name (outsec->owner, outsec);
 494
 495   outdefsec = info->defsec->output_section;
 496   outdefsecname = bfd_get_section_name (outdefsec->owner, outdefsec);
 497
 498   /* The section where the symbol is defined is permitted.  */
 499   if (strcmp (outsecname, outdefsecname) == 0)
 500     return;
 501
 502   for (ncr = info->ncrs->list; ncr != NULL; ncr = ncr->next)
 503     if (strcmp (outsecname, ncr->name) == 0)
 504       break;
 505
 506   if (ncr == NULL)
 507     return;
 508
 509   /* This section is one for which cross references are prohibited.
 510      Look through the relocations, and see if any of them are to
 511      INFO->H.  */
 512
 513   symname = info->h->root.string;
 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 = (arelent **) 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           && (strcmp (bfd_asymbol_name (*q->sym_ptr_ptr), symname) == 0
 535               || (info->same
 536                   && bfd_get_section (*q->sym_ptr_ptr) == info->defsec)))
 537         {
 538           /* We found a reloc for the symbol.  The symbol is defined
 539              in OUTSECNAME.  This reloc is from a section which is
 540              mapped into a section from which references to OUTSECNAME
 541              are prohibited.  We must report an error.  */
 542           einfo (_("%X%C: prohibited cross reference from %s to `%T' in %s\n"),
 543                  abfd, sec, q->address, outsecname,
 544                  bfd_asymbol_name (*q->sym_ptr_ptr), outdefsecname);
 545         }
 546     }
 547
 548   free (relpp);
 549 }