ld/ldwrite.c

   1 /* ldwrite.c -- write out the linked file
   2    Copyright (C) 1991, 92, 93, 94, 95, 96, 97, 1998
   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 *, 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
 296
 297 /* Wander around the input sections, make sure that
 298    we'll never try and create an output section with more relocs
 299    than will fit.. Do this by always assuming the worst case, and
 300    creating new output sections with all the right bits */
 301 #define TESTIT 1
 302 static asection *
 303 clone_section (abfd, s, count)
 304      bfd *abfd;
 305      asection *s;
 306      int *count;
 307 {
 308   char sname[8];                /* ??  find the name for this size */
 309   asection *n;
 310   struct bfd_link_hash_entry *h;
 311   /* Invent a section name - use first five
 312      chars of base section name and a digit suffix */
 313   do
 314     {
 315       unsigned int i;
 316       char b[6];
 317       for (i = 0; i < sizeof (b) - 1 && s->name[i]; i++)
 318         b[i] = s->name[i];
 319       b[i] = 0;
 320       sprintf (sname, "%s%d", b, (*count)++);
 321     }
 322   while (bfd_get_section_by_name (abfd, sname));
 323
 324   n = bfd_make_section_anyway (abfd, xstrdup (sname));
 325
 326   /* Create a symbol of the same name */
 327
 328   h = bfd_link_hash_lookup (link_info.hash,
 329                             sname, true, true, false);
 330   h->type = bfd_link_hash_defined;
 331   h->u.def.value = 0;
 332   h->u.def.section = n   ;
 333
 334
 335   n->flags = s->flags;
 336   n->vma = s->vma;
 337   n->user_set_vma = s->user_set_vma;
 338   n->lma = s->lma;
 339   n->_cooked_size = 0;
 340   n->_raw_size = 0;
 341   n->output_offset = s->output_offset;
 342   n->output_section = n;
 343   n->orelocation = 0;
 344   n->reloc_count = 0;
 345   n->alignment_power = s->alignment_power;
 346   return n;
 347 }
 348
 349 #if TESTING
 350 static void
 351 ds (s)
 352      asection *s;
 353 {
 354   struct bfd_link_order *l = s->link_order_head;
 355   printf ("vma %x size %x\n", s->vma, s->_raw_size);
 356   while (l)
 357     {
 358       if (l->type == bfd_indirect_link_order)
 359         {
 360           printf ("%8x %s\n", l->offset, l->u.indirect.section->owner->filename);
 361         }
 362       else
 363         {
 364           printf (_("%8x something else\n"), l->offset);
 365         }
 366       l = l->next;
 367     }
 368   printf ("\n");
 369 }
 370 dump (s, a1, a2)
 371      char *s;
 372      asection *a1;
 373      asection *a2;
 374 {
 375   printf ("%s\n", s);
 376   ds (a1);
 377   ds (a2);
 378 }
 379
 380 static void
 381 sanity_check (abfd)
 382      bfd *abfd;
 383 {
 384   asection *s;
 385   for (s = abfd->sections; s; s = s->next)
 386     {
 387       struct bfd_link_order *p;
 388       bfd_vma prev = 0;
 389       for (p = s->link_order_head; p; p = p->next)
 390         {
 391           if (p->offset > 100000)
 392             abort ();
 393           if (p->offset < prev)
 394             abort ();
 395           prev = p->offset;
 396         }
 397     }
 398 }
 399 #else
 400 #define sanity_check(a)
 401 #define dump(a, b, c)
 402 #endif
 403
 404 static void
 405 split_sections (abfd, info)
 406      bfd *abfd;
 407      struct bfd_link_info *info;
 408 {
 409   asection *original_sec;
 410   int nsecs = abfd->section_count;
 411   sanity_check (abfd);
 412   /* look through all the original sections */
 413   for (original_sec = abfd->sections;
 414        original_sec && nsecs;
 415        original_sec = original_sec->next, nsecs--)
 416     {
 417       boolean first = true;
 418       int count = 0;
 419       int lines = 0;
 420       int relocs = 0;
 421       struct bfd_link_order **pp;
 422       bfd_vma vma = original_sec->vma;
 423       bfd_vma shift_offset = 0;
 424       asection *cursor = original_sec;
 425
 426       /* count up the relocations and line entries to see if
 427          anything would be too big to fit */
 428       for (pp = &(cursor->link_order_head); *pp; pp = &((*pp)->next))
 429         {
 430           struct bfd_link_order *p = *pp;
 431           int thislines = 0;
 432           int thisrelocs = 0;
 433           if (p->type == bfd_indirect_link_order)
 434             {
 435               asection *sec;
 436
 437               sec = p->u.indirect.section;
 438
 439               if (info->strip == strip_none
 440                   || info->strip == strip_some)
 441                 thislines = sec->lineno_count;
 442
 443               if (info->relocateable)
 444                 thisrelocs = sec->reloc_count;
 445
 446             }
 447           else if (info->relocateable
 448                    && (p->type == bfd_section_reloc_link_order
 449                        || p->type == bfd_symbol_reloc_link_order))
 450             thisrelocs++;
 451
 452           if (! first
 453               && (thisrelocs + relocs > config.split_by_reloc
 454                   || thislines + lines > config.split_by_reloc
 455                   || config.split_by_file))
 456             {
 457               /* create a new section and put this link order and the
 458                  following link orders into it */
 459               struct bfd_link_order *l = p;
 460               asection *n = clone_section (abfd, cursor, &count);
 461               *pp = NULL;       /* Snip off link orders from old section */
 462               n->link_order_head = l;   /* attach to new section */
 463               pp = &n->link_order_head;
 464
 465               /* change the size of the original section and
 466                  update the vma of the new one */
 467
 468               dump ("before snip", cursor, n);
 469
 470               n->_raw_size = cursor->_raw_size - l->offset;
 471               cursor->_raw_size = l->offset;
 472
 473               vma += cursor->_raw_size;
 474               n->lma = n->vma = vma;
 475
 476               shift_offset = l->offset;
 477
 478               /* run down the chain and change the output section to
 479                  the right one, update the offsets too */
 480
 481               while (l)
 482                 {
 483                   l->offset -= shift_offset;
 484                   if (l->type == bfd_indirect_link_order)
 485                     {
 486                       l->u.indirect.section->output_section = n;
 487                       l->u.indirect.section->output_offset = l->offset;
 488                     }
 489                   l = l->next;
 490                 }
 491               dump ("after snip", cursor, n);
 492               cursor = n;
 493               relocs = thisrelocs;
 494               lines = thislines;
 495             }
 496           else
 497             {
 498               relocs += thisrelocs;
 499               lines += thislines;
 500             }
 501
 502           first = false;
 503         }
 504     }
 505   sanity_check (abfd);
 506 }
 507 /**********************************************************************/
 508 void
 509 ldwrite ()
 510 {
 511   /* Reset error indicator, which can typically something like invalid
 512      format from openning up the .o files */
 513   bfd_set_error (bfd_error_no_error);
 514   lang_for_each_statement (build_link_order);
 515
 516   if (config.split_by_reloc || config.split_by_file)
 517     split_sections (output_bfd, &link_info);
 518   if (!bfd_final_link (output_bfd, &link_info))
 519     {
 520       /* If there was an error recorded, print it out.  Otherwise assume
 521          an appropriate error message like unknown symbol was printed
 522          out.  */
 523
 524       if (bfd_get_error () != bfd_error_no_error)
 525         einfo (_("%F%P: final link failed: %E\n"), output_bfd);
 526       else
 527         xexit(1);
 528     }
 529 }