ld/ldwrite.c

   1 /* ldwrite.c -- write out the linked file
   2    Copyright 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 2000
   3    Free Software Foundation, Inc.
   4    Written by Steve Chamberlain sac@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 #include "bfd.h"
  23 #include "sysdep.h"
  24 #include "bfdlink.h"
  25 #include "libiberty.h"
  26
  27 #include "ld.h"
  28 #include "ldexp.h"
  29 #include "ldlang.h"
  30 #include "ldwrite.h"
  31 #include "ldmisc.h"
  32 #include "ldgram.h"
  33 #include "ldmain.h"
  34
  35 static void build_link_order PARAMS ((lang_statement_union_type *));
  36 static asection *clone_section PARAMS ((bfd *, asection *, const char *, int *));
  37 static void split_sections PARAMS ((bfd *, struct bfd_link_info *));
  38
  39 /* Build link_order structures for the BFD linker.  */
  40
  41 static void
  42 build_link_order (statement)
  43      lang_statement_union_type *statement;
  44 {
  45   switch (statement->header.type)
  46     {
  47     case lang_data_statement_enum:
  48       {
  49         asection *output_section;
  50         struct bfd_link_order *link_order;
  51         bfd_vma value;
  52         boolean big_endian = false;
  53
  54         output_section = statement->data_statement.output_section;
  55         ASSERT (output_section->owner == output_bfd);
  56
  57         link_order = bfd_new_link_order (output_bfd, output_section);
  58         if (link_order == NULL)
  59           einfo (_("%P%F: bfd_new_link_order failed\n"));
  60
  61         link_order->type = bfd_data_link_order;
  62         link_order->offset = statement->data_statement.output_vma;
  63         link_order->u.data.contents = (bfd_byte *) xmalloc (QUAD_SIZE);
  64
  65         value = statement->data_statement.value;
  66
  67         /* If the endianness of the output BFD is not known, then we
  68            base the endianness of the data on the first input file.
  69            By convention, the bfd_put routines for an unknown
  70            endianness are big endian, so we must swap here if the
  71            input file is little endian.  */
  72         if (bfd_big_endian (output_bfd))
  73           big_endian = true;
  74         else if (bfd_little_endian (output_bfd))
  75           big_endian = false;
  76         else
  77           {
  78             boolean swap;
  79
  80             swap = false;
  81             if (command_line.endian == ENDIAN_BIG)
  82               big_endian = true;
  83             else if (command_line.endian == ENDIAN_LITTLE)
  84               {
  85                 big_endian = false;
  86                 swap = true;
  87               }
  88             else if (command_line.endian == ENDIAN_UNSET)
  89               {
  90                 big_endian = true;
  91                 {
  92                   LANG_FOR_EACH_INPUT_STATEMENT (s)
  93                     {
  94                       if (s->the_bfd != NULL)
  95                         {
  96                           if (bfd_little_endian (s->the_bfd))
  97                             {
  98                               big_endian = false;
  99                               swap = true;
 100                             }
 101                           break;
 102                         }
 103                     }
 104                 }
 105               }
 106
 107             if (swap)
 108               {
 109                 bfd_byte buffer[8];
 110
 111                 switch (statement->data_statement.type)
 112                   {
 113                   case QUAD:
 114                   case SQUAD:
 115                     if (sizeof (bfd_vma) >= QUAD_SIZE)
 116                       {
 117                         bfd_putl64 (value, buffer);
 118                         value = bfd_getb64 (buffer);
 119                         break;
 120                       }
 121                     /* Fall through.  */
 122                   case LONG:
 123                     bfd_putl32 (value, buffer);
 124                     value = bfd_getb32 (buffer);
 125                     break;
 126                   case SHORT:
 127                     bfd_putl16 (value, buffer);
 128                     value = bfd_getb16 (buffer);
 129                     break;
 130                   case BYTE:
 131                     break;
 132                   default:
 133                     abort ();
 134                   }
 135               }
 136           }
 137
 138         ASSERT (output_section->owner == output_bfd);
 139         switch (statement->data_statement.type)
 140           {
 141           case QUAD:
 142           case SQUAD:
 143             if (sizeof (bfd_vma) >= QUAD_SIZE)
 144               bfd_put_64 (output_bfd, value, link_order->u.data.contents);
 145             else
 146               {
 147                 bfd_vma high;
 148
 149                 if (statement->data_statement.type == QUAD)
 150                   high = 0;
 151                 else if ((value & 0x80000000) == 0)
 152                   high = 0;
 153                 else
 154                   high = (bfd_vma) -1;
 155                 bfd_put_32 (output_bfd, high,
 156                             (link_order->u.data.contents
 157                              + (big_endian ? 0 : 4)));
 158                 bfd_put_32 (output_bfd, value,
 159                             (link_order->u.data.contents
 160                              + (big_endian ? 4 : 0)));
 161               }
 162             link_order->size = QUAD_SIZE;
 163             break;
 164           case LONG:
 165             bfd_put_32 (output_bfd, value, link_order->u.data.contents);
 166             link_order->size = LONG_SIZE;
 167             break;
 168           case SHORT:
 169             bfd_put_16 (output_bfd, value, link_order->u.data.contents);
 170             link_order->size = SHORT_SIZE;
 171             break;
 172           case BYTE:
 173             bfd_put_8 (output_bfd, value, link_order->u.data.contents);
 174             link_order->size = BYTE_SIZE;
 175             break;
 176           default:
 177             abort ();
 178           }
 179       }
 180       break;
 181
 182     case lang_reloc_statement_enum:
 183       {
 184         lang_reloc_statement_type *rs;
 185         asection *output_section;
 186         struct bfd_link_order *link_order;
 187
 188         rs = &statement->reloc_statement;
 189
 190         output_section = rs->output_section;
 191         ASSERT (output_section->owner == output_bfd);
 192
 193         link_order = bfd_new_link_order (output_bfd, output_section);
 194         if (link_order == NULL)
 195           einfo (_("%P%F: bfd_new_link_order failed\n"));
 196
 197         link_order->offset = rs->output_vma;
 198         link_order->size = bfd_get_reloc_size (rs->howto);
 199
 200         link_order->u.reloc.p =
 201           ((struct bfd_link_order_reloc *)
 202            xmalloc (sizeof (struct bfd_link_order_reloc)));
 203
 204         link_order->u.reloc.p->reloc = rs->reloc;
 205         link_order->u.reloc.p->addend = rs->addend_value;
 206
 207         if (rs->name == NULL)
 208           {
 209             link_order->type = bfd_section_reloc_link_order;
 210             if (rs->section->owner == output_bfd)
 211               link_order->u.reloc.p->u.section = rs->section;
 212             else
 213               {
 214                 link_order->u.reloc.p->u.section = rs->section->output_section;
 215                 link_order->u.reloc.p->addend += rs->section->output_offset;
 216               }
 217           }
 218         else
 219           {
 220             link_order->type = bfd_symbol_reloc_link_order;
 221             link_order->u.reloc.p->u.name = rs->name;
 222           }
 223       }
 224       break;
 225
 226     case lang_input_section_enum:
 227       /* Create a new link_order in the output section with this
 228          attached */
 229       if (statement->input_section.ifile->just_syms_flag == false)
 230         {
 231           asection *i = statement->input_section.section;
 232           asection *output_section = i->output_section;
 233
 234           ASSERT (output_section->owner == output_bfd);
 235
 236           if ((output_section->flags & SEC_HAS_CONTENTS) != 0)
 237             {
 238               struct bfd_link_order *link_order;
 239
 240               link_order = bfd_new_link_order (output_bfd, output_section);
 241
 242               if (i->flags & SEC_NEVER_LOAD)
 243                 {
 244                   /* We've got a never load section inside one which
 245                      is going to be output, we'll change it into a
 246                      fill link_order */
 247                   link_order->type = bfd_fill_link_order;
 248                   link_order->u.fill.value = 0;
 249                 }
 250               else
 251                 {
 252                   link_order->type = bfd_indirect_link_order;
 253                   link_order->u.indirect.section = i;
 254                   ASSERT (i->output_section == output_section);
 255                 }
 256               if (i->_cooked_size)
 257                 link_order->size = i->_cooked_size;
 258               else
 259                 link_order->size = bfd_get_section_size_before_reloc (i);
 260               link_order->offset = i->output_offset;
 261             }
 262         }
 263       break;
 264
 265     case lang_padding_statement_enum:
 266       /* Make a new link_order with the right filler */
 267       {
 268         asection *output_section;
 269         struct bfd_link_order *link_order;
 270
 271         output_section = statement->padding_statement.output_section;
 272         ASSERT (statement->padding_statement.output_section->owner
 273                 == output_bfd);
 274         if ((output_section->flags & SEC_HAS_CONTENTS) != 0)
 275           {
 276             link_order = bfd_new_link_order (output_bfd, output_section);
 277             link_order->type = bfd_fill_link_order;
 278             link_order->size = statement->padding_statement.size;
 279             link_order->offset = statement->padding_statement.output_offset;
 280             link_order->u.fill.value = statement->padding_statement.fill;
 281           }
 282       }
 283       break;
 284
 285     default:
 286       /* All the other ones fall through */
 287       break;
 288     }
 289 }
 290
 291 /* Call BFD to write out the linked file.  */
 292
 293 /**********************************************************************/
 294
 295 /* Wander around the input sections, make sure that
 296    we'll never try and create an output section with more relocs
 297    than will fit.. Do this by always assuming the worst case, and
 298    creating new output sections with all the right bits.  */
 299 #define TESTIT 1
 300 static asection *
 301 clone_section (abfd, s, name, count)
 302      bfd *abfd;
 303      asection *s;
 304      const char *name;
 305      int *count;
 306 {
 307   char templ[6];
 308   char *sname;
 309   asection *n;
 310   struct bfd_link_hash_entry *h;
 311
 312   /* Invent a section name from the first five chars of the base
 313      section name and a digit suffix.  */
 314   strncpy (templ, name, sizeof (templ) - 1);
 315   templ[sizeof (templ) - 1] = '\0';
 316   if ((sname = bfd_get_unique_section_name (abfd, templ, count)) == NULL
 317       || (n = bfd_make_section_anyway (abfd, sname)) == NULL
 318       || (h = bfd_link_hash_lookup (link_info.hash,
 319                                     sname, true, true, false)) == NULL)
 320     {
 321       einfo (_("%F%P: clone section failed: %E\n"));
 322       /* Silence gcc warnings.  einfo exits, so we never reach here.  */
 323       return NULL;
 324     }
 325
 326   /* Set up section symbol.  */
 327   h->type = bfd_link_hash_defined;
 328   h->u.def.value = 0;
 329   h->u.def.section = n;
 330
 331   n->flags = s->flags;
 332   n->vma = s->vma;
 333   n->user_set_vma = s->user_set_vma;
 334   n->lma = s->lma;
 335   n->_cooked_size = 0;
 336   n->_raw_size = 0;
 337   n->output_offset = s->output_offset;
 338   n->output_section = n;
 339   n->orelocation = 0;
 340   n->reloc_count = 0;
 341   n->alignment_power = s->alignment_power;
 342   return n;
 343 }
 344
 345 #if TESTING
 346 static void
 347 ds (s)
 348      asection *s;
 349 {
 350   struct bfd_link_order *l = s->link_order_head;
 351   printf ("vma %x size %x\n", s->vma, s->_raw_size);
 352   while (l)
 353     {
 354       if (l->type == bfd_indirect_link_order)
 355         {
 356           printf ("%8x %s\n", l->offset, l->u.indirect.section->owner->filename);
 357         }
 358       else
 359         {
 360           printf (_("%8x something else\n"), l->offset);
 361         }
 362       l = l->next;
 363     }
 364   printf ("\n");
 365 }
 366
 367 dump (s, a1, a2)
 368      char *s;
 369      asection *a1;
 370      asection *a2;
 371 {
 372   printf ("%s\n", s);
 373   ds (a1);
 374   ds (a2);
 375 }
 376
 377 static void
 378 sanity_check (abfd)
 379      bfd *abfd;
 380 {
 381   asection *s;
 382   for (s = abfd->sections; s; s = s->next)
 383     {
 384       struct bfd_link_order *p;
 385       bfd_vma prev = 0;
 386       for (p = s->link_order_head; p; p = p->next)
 387         {
 388           if (p->offset > 100000)
 389             abort ();
 390           if (p->offset < prev)
 391             abort ();
 392           prev = p->offset;
 393         }
 394     }
 395 }
 396 #else
 397 #define sanity_check(a)
 398 #define dump(a, b, c)
 399 #endif
 400
 401 static void
 402 split_sections (abfd, info)
 403      bfd *abfd;
 404      struct bfd_link_info *info;
 405 {
 406   asection *original_sec;
 407   int nsecs = abfd->section_count;
 408   sanity_check (abfd);
 409   /* Look through all the original sections.  */
 410   for (original_sec = abfd->sections;
 411        original_sec && nsecs;
 412        original_sec = original_sec->next, nsecs--)
 413     {
 414       int count = 0;
 415       unsigned int lines = 0;
 416       unsigned int relocs = 0;
 417       bfd_size_type sec_size = 0;
 418       struct bfd_link_order *l;
 419       struct bfd_link_order *p;
 420       bfd_vma vma = original_sec->vma;
 421       asection *cursor = original_sec;
 422
 423       /* Count up the relocations and line entries to see if anything
 424          would be too big to fit.  Accumulate section size too.  */
 425       for (l = NULL, p = cursor->link_order_head; p != NULL; p = l->next)
 426         {
 427           unsigned int thislines = 0;
 428           unsigned int thisrelocs = 0;
 429           bfd_size_type thissize = 0;
 430           if (p->type == bfd_indirect_link_order)
 431             {
 432               asection *sec;
 433
 434               sec = p->u.indirect.section;
 435
 436               if (info->strip == strip_none
 437                   || info->strip == strip_some)
 438                 thislines = sec->lineno_count;
 439
 440               if (info->relocateable)
 441                 thisrelocs = sec->reloc_count;
 442
 443               if (sec->_cooked_size != 0)
 444                 thissize = sec->_cooked_size;
 445               else
 446                 thissize = sec->_raw_size;
 447
 448             }
 449           else if (info->relocateable
 450                    && (p->type == bfd_section_reloc_link_order
 451                        || p->type == bfd_symbol_reloc_link_order))
 452             thisrelocs++;
 453
 454           if (l != NULL
 455               && (thisrelocs + relocs >= config.split_by_reloc
 456                   || thislines + lines >= config.split_by_reloc
 457                   || thissize + sec_size >= config.split_by_file))
 458             {
 459               /* Create a new section and put this link order and the
 460                  following link orders into it.  */
 461               bfd_vma shift_offset;
 462               asection *n;
 463
 464               n = clone_section (abfd, cursor, original_sec->name, &count);
 465
 466               /* Attach the link orders to the new section and snip
 467                  them off from the old section.  */
 468               n->link_order_head = p;
 469               n->link_order_tail = cursor->link_order_tail;
 470               cursor->link_order_tail = l;
 471               l->next = NULL;
 472               l = p;
 473
 474               /* Change the size of the original section and
 475                  update the vma of the new one.  */
 476
 477               dump ("before snip", cursor, n);
 478
 479               shift_offset = p->offset;
 480               if (cursor->_cooked_size != 0)
 481                 {
 482                   n->_cooked_size = cursor->_cooked_size - shift_offset;
 483                   cursor->_cooked_size = shift_offset;
 484                 }
 485               n->_raw_size = cursor->_raw_size - shift_offset;
 486               cursor->_raw_size = shift_offset;
 487
 488               vma += shift_offset;
 489               n->lma = n->vma = vma;
 490
 491               /* Run down the chain and change the output section to
 492                  the right one, update the offsets too.  */
 493               do
 494                 {
 495                   p->offset -= shift_offset;
 496                   if (p->type == bfd_indirect_link_order)
 497                     {
 498                       p->u.indirect.section->output_section = n;
 499                       p->u.indirect.section->output_offset = p->offset;
 500                     }
 501                   p = p->next;
 502                 }
 503               while (p);
 504
 505               dump ("after snip", cursor, n);
 506               cursor = n;
 507               relocs = thisrelocs;
 508               lines = thislines;
 509               sec_size = thissize;
 510             }
 511           else
 512             {
 513               l = p;
 514               relocs += thisrelocs;
 515               lines += thislines;
 516               sec_size += thissize;
 517             }
 518         }
 519     }
 520   sanity_check (abfd);
 521 }
 522
 523 /**********************************************************************/
 524
 525 void
 526 ldwrite ()
 527 {
 528   /* Reset error indicator, which can typically something like invalid
 529      format from opening up the .o files.  */
 530   bfd_set_error (bfd_error_no_error);
 531   lang_for_each_statement (build_link_order);
 532
 533   if (config.split_by_reloc != (unsigned) -1
 534       || config.split_by_file != (bfd_size_type) -1)
 535     split_sections (output_bfd, &link_info);
 536   if (!bfd_final_link (output_bfd, &link_info))
 537     {
 538       /* If there was an error recorded, print it out.  Otherwise assume
 539          an appropriate error message like unknown symbol was printed
 540          out.  */
 541
 542       if (bfd_get_error () != bfd_error_no_error)
 543         einfo (_("%F%P: final link failed: %E\n"));
 544       else
 545         xexit (1);
 546     }
 547 }