ld/ldcref.c

   1 /* ldcref.c -- output a cross reference table
   2    Copyright (C) 1996 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;
 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
 238   fprintf (fp, "\nCross Reference Table\n\n");
 239   fprintf (fp, "Symbol");
 240   len = sizeof "Symbol" - 1;
 241   while (len < FILECOL)
 242     {
 243       putc (' ' , fp);
 244       ++len;
 245     }
 246   fprintf (fp, "File\n");
 247
 248   if (! cref_initialized)
 249     {
 250       fprintf (fp, "No symbols\n");
 251       return;
 252     }
 253
 254   csyms = ((struct cref_hash_entry **)
 255            xmalloc (cref_symcount * sizeof (*csyms)));
 256
 257   csym_fill = csyms;
 258   cref_hash_traverse (&cref_table, cref_fill_array, &csym_fill);
 259   ASSERT (csym_fill - csyms == cref_symcount);
 260
 261   qsort (csyms, cref_symcount, sizeof (*csyms), cref_sort_array);
 262
 263   csym_end = csyms + cref_symcount;
 264   for (csym = csyms; csym < csym_end; csym++)
 265     output_one_cref (fp, *csym);
 266 }
 267
 268 /* Output one entry in the cross reference table.  */
 269
 270 static void
 271 output_one_cref (fp, h)
 272      FILE *fp;
 273      struct cref_hash_entry *h;
 274 {
 275   int len;
 276   struct bfd_link_hash_entry *hl;
 277   struct cref_ref *r;
 278
 279   hl = bfd_link_hash_lookup (link_info.hash, h->root.string, false,
 280                              false, true);
 281   if (hl == NULL)
 282     einfo ("%P: symbol `%T' missing from main hash table\n",
 283            h->root.string);
 284   else
 285     {
 286       /* If this symbol is defined in a dynamic object but never
 287          referenced by a normal object, then don't print it.  */
 288       if (hl->type == bfd_link_hash_defined)
 289         {
 290           if (hl->u.def.section->output_section == NULL)
 291             return;
 292           if (hl->u.def.section->owner != NULL
 293               && (hl->u.def.section->owner->flags & DYNAMIC) != 0)
 294             {
 295               for (r = h->refs; r != NULL; r = r->next)
 296                 if ((r->abfd->flags & DYNAMIC) == 0)
 297                   break;
 298               if (r == NULL)
 299                 return;
 300             }
 301         }
 302     }
 303
 304   fprintf (fp, "%s ", h->demangled);
 305   len = strlen (h->demangled) + 1;
 306
 307   for (r = h->refs; r != NULL; r = r->next)
 308     {
 309       if (r->def)
 310         {
 311           while (len < FILECOL)
 312             {
 313               putc (' ', fp);
 314               ++len;
 315             }
 316           finfo (fp, "%B\n", r->abfd);
 317           len = 0;
 318         }
 319     }
 320
 321   for (r = h->refs; r != NULL; r = r->next)
 322     {
 323       if (! r->def)
 324         {
 325           while (len < FILECOL)
 326             {
 327               putc (' ', fp);
 328               ++len;
 329             }
 330           finfo (fp, "%B\n", r->abfd);
 331           len = 0;
 332         }
 333     }
 334
 335   ASSERT (len == 0);
 336 }
 337
 338 /* Check for prohibited cross references.  */
 339
 340 void
 341 check_nocrossrefs ()
 342 {
 343   if (! cref_initialized)
 344     return;
 345
 346   cref_hash_traverse (&cref_table, check_nocrossref, (PTR) NULL);
 347 }
 348
 349 /* Check one symbol to see if it is a prohibited cross reference.  */
 350
 351 /*ARGSUSED*/
 352 static boolean
 353 check_nocrossref (h, ignore)
 354      struct cref_hash_entry *h;
 355      PTR ignore;
 356 {
 357   struct bfd_link_hash_entry *hl;
 358   asection *defsec;
 359   const char *defsecname;
 360   struct lang_nocrossrefs *ncrs;
 361   struct lang_nocrossref *ncr;
 362
 363   hl = bfd_link_hash_lookup (link_info.hash, h->root.string, false,
 364                              false, true);
 365   if (hl == NULL)
 366     {
 367       einfo ("%P: symbol `%T' missing from main hash table\n",
 368              h->root.string);
 369       return true;
 370     }
 371
 372   if (hl->type != bfd_link_hash_defined
 373       && hl->type != bfd_link_hash_defweak)
 374     return true;
 375
 376   defsec = hl->u.def.section->output_section;
 377   if (defsec == NULL)
 378     return true;
 379   defsecname = bfd_get_section_name (defsec->owner, defsec);
 380
 381   for (ncrs = nocrossref_list; ncrs != NULL; ncrs = ncrs->next)
 382     for (ncr = ncrs->list; ncr != NULL; ncr = ncr->next)
 383       if (strcmp (ncr->name, defsecname) == 0)
 384         check_refs (h, hl, ncrs);
 385
 386   return true;
 387 }
 388
 389 /* The struct is used to pass information from check_refs to
 390    check_reloc_refs through bfd_map_over_sections.  */
 391
 392 struct check_refs_info
 393 {
 394   struct cref_hash_entry *h;
 395   asection *defsec;
 396   struct lang_nocrossrefs *ncrs;
 397   asymbol **asymbols;
 398   boolean same;
 399 };
 400
 401 /* This function is called for each symbol defined in a section which
 402    prohibits cross references.  We need to look through all references
 403    to this symbol, and ensure that the references are not from
 404    prohibited sections.  */
 405
 406 static void
 407 check_refs (h, hl, ncrs)
 408      struct cref_hash_entry *h;
 409      struct bfd_link_hash_entry *hl;
 410      struct lang_nocrossrefs *ncrs;
 411 {
 412   struct cref_ref *ref;
 413
 414   for (ref = h->refs; ref != NULL; ref = ref->next)
 415     {
 416       lang_input_statement_type *li;
 417       asymbol **asymbols;
 418       struct check_refs_info info;
 419
 420       /* We need to look through the relocations for this BFD, to see
 421          if any of the relocations which refer to this symbol are from
 422          a prohibited section.  Note that we need to do this even for
 423          the BFD in which the symbol is defined, since even a single
 424          BFD might contain a prohibited cross reference; for this
 425          case, we set the SAME field in INFO, which will cause
 426          CHECK_RELOCS_REFS to check for relocations against the
 427          section as well as against the symbol.  */
 428
 429       li = (lang_input_statement_type *) ref->abfd->usrdata;
 430       if (li != NULL && li->asymbols != NULL)
 431         asymbols = li->asymbols;
 432       else
 433         {
 434           long symsize;
 435           long symbol_count;
 436
 437           symsize = bfd_get_symtab_upper_bound (ref->abfd);
 438           if (symsize < 0)
 439             einfo ("%B%F: could not read symbols; %E\n", ref->abfd);
 440           asymbols = (asymbol **) xmalloc (symsize);
 441           symbol_count = bfd_canonicalize_symtab (ref->abfd, asymbols);
 442           if (symbol_count < 0)
 443             einfo ("%B%F: could not read symbols: %E\n", ref->abfd);
 444           if (li != NULL)
 445             {
 446               li->asymbols = asymbols;
 447               li->symbol_count = symbol_count;
 448             }
 449         }
 450
 451       info.h = h;
 452       info.defsec = hl->u.def.section;
 453       info.ncrs = ncrs;
 454       info.asymbols = asymbols;
 455       if (ref->abfd == hl->u.def.section->owner)
 456         info.same = true;
 457       else
 458         info.same = false;
 459       bfd_map_over_sections (ref->abfd, check_reloc_refs, (PTR) &info);
 460
 461       if (li == NULL)
 462         free (asymbols);
 463     }
 464 }
 465
 466 /* This is called via bfd_map_over_sections.  INFO->H is a symbol
 467    defined in INFO->DEFSECNAME.  If this section maps into any of the
 468    sections listed in INFO->NCRS, other than INFO->DEFSECNAME, then we
 469    look through the relocations.  If any of the relocations are to
 470    INFO->H, then we report a prohibited cross reference error.  */
 471
 472 static void
 473 check_reloc_refs (abfd, sec, iarg)
 474      bfd *abfd;
 475      asection *sec;
 476      PTR iarg;
 477 {
 478   struct check_refs_info *info = (struct check_refs_info *) iarg;
 479   asection *outsec;
 480   const char *outsecname;
 481   asection *outdefsec;
 482   const char *outdefsecname;
 483   struct lang_nocrossref *ncr;
 484   const char *symname;
 485   long relsize;
 486   arelent **relpp;
 487   long relcount;
 488   arelent **p, **pend;
 489
 490   outsec = sec->output_section;
 491   outsecname = bfd_get_section_name (outsec->owner, outsec);
 492
 493   outdefsec = info->defsec->output_section;
 494   outdefsecname = bfd_get_section_name (outdefsec->owner, outdefsec);
 495
 496   /* The section where the symbol is defined is permitted.  */
 497   if (strcmp (outsecname, outdefsecname) == 0)
 498     return;
 499
 500   for (ncr = info->ncrs->list; ncr != NULL; ncr = ncr->next)
 501     if (strcmp (outsecname, ncr->name) == 0)
 502       break;
 503
 504   if (ncr == NULL)
 505     return;
 506
 507   /* This section is one for which cross references are prohibited.
 508      Look through the relocations, and see if any of them are to
 509      INFO->H.  */
 510
 511   symname = info->h->root.string;
 512
 513   relsize = bfd_get_reloc_upper_bound (abfd, sec);
 514   if (relsize < 0)
 515     einfo ("%B%F: could not read relocs: %E\n", abfd);
 516   if (relsize == 0)
 517     return;
 518
 519   relpp = (arelent **) xmalloc (relsize);
 520   relcount = bfd_canonicalize_reloc (abfd, sec, relpp, info->asymbols);
 521   if (relcount < 0)
 522     einfo ("%B%F: could not read relocs: %E\n", abfd);
 523
 524   p = relpp;
 525   pend = p + relcount;
 526   for (; p < pend && *p != NULL; p++)
 527     {
 528       arelent *q = *p;
 529
 530       if (q->sym_ptr_ptr != NULL
 531           && *q->sym_ptr_ptr != NULL
 532           && (strcmp (bfd_asymbol_name (*q->sym_ptr_ptr), symname) == 0
 533               || (info->same
 534                   && *q->sym_ptr_ptr == info->defsec->symbol)))
 535         {
 536           /* We found a reloc for the symbol.  The symbol is defined
 537              in OUTSECNAME.  This reloc is from a section which is
 538              mapped into a section from which references to OUTSECNAME
 539              are prohibited.  We must report an error.  */
 540           einfo ("%X%C: prohibited cross reference from %s to `%T' in %s\n",
 541                  abfd, sec, q->address, outsecname,
 542                  bfd_asymbol_name (*q->sym_ptr_ptr), outdefsecname);
 543         }
 544     }
 545
 546   free (relpp);
 547 }