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 #define SSIZE 8
 309   char sname[SSIZE];            /* ??  find the name for this size */
 310   asection *n;
 311   struct bfd_link_hash_entry *h;
 312   /* Invent a section name - use first five
 313      chars of base section name and a digit suffix */
 314   do
 315     {
 316       unsigned int i;
 317       char b[6];
 318       for (i = 0; i < sizeof (b) - 1 && s->name[i]; i++)
 319         b[i] = s->name[i];
 320       b[i] = 0;
 321       sprintf (sname, "%s%d", b, (*count)++);
 322     }
 323   while (bfd_get_section_by_name (abfd, sname));
 324
 325   n = bfd_make_section_anyway (abfd, xstrdup (sname));
 326
 327   /* Create a symbol of the same name */
 328
 329   h = bfd_link_hash_lookup (link_info.hash,
 330                             sname, true, true, false);
 331   h->type = bfd_link_hash_defined;
 332   h->u.def.value = 0;
 333   h->u.def.section = n   ;
 334
 335
 336   n->flags = s->flags;
 337   n->vma = s->vma;
 338   n->user_set_vma = s->user_set_vma;
 339   n->lma = s->lma;
 340   n->_cooked_size = 0;
 341   n->_raw_size = 0;
 342   n->output_offset = s->output_offset;
 343   n->output_section = n;
 344   n->orelocation = 0;
 345   n->reloc_count = 0;
 346   n->alignment_power = s->alignment_power;
 347   return n;
 348 }
 349
 350 #if TESTING
 351 static void
 352 ds (s)
 353      asection *s;
 354 {
 355   struct bfd_link_order *l = s->link_order_head;
 356   printf ("vma %x size %x\n", s->vma, s->_raw_size);
 357   while (l)
 358     {
 359       if (l->type == bfd_indirect_link_order)
 360         {
 361           printf ("%8x %s\n", l->offset, l->u.indirect.section->owner->filename);
 362         }
 363       else
 364         {
 365           printf (_("%8x something else\n"), l->offset);
 366         }
 367       l = l->next;
 368     }
 369   printf ("\n");
 370 }
 371 dump (s, a1, a2)
 372      char *s;
 373      asection *a1;
 374      asection *a2;
 375 {
 376   printf ("%s\n", s);
 377   ds (a1);
 378   ds (a2);
 379 }
 380
 381 static void
 382 sanity_check (abfd)
 383      bfd *abfd;
 384 {
 385   asection *s;
 386   for (s = abfd->sections; s; s = s->next)
 387     {
 388       struct bfd_link_order *p;
 389       bfd_vma prev = 0;
 390       for (p = s->link_order_head; p; p = p->next)
 391         {
 392           if (p->offset > 100000)
 393             abort ();
 394           if (p->offset < prev)
 395             abort ();
 396           prev = p->offset;
 397         }
 398     }
 399 }
 400 #else
 401 #define sanity_check(a)
 402 #define dump(a, b, c)
 403 #endif
 404
 405 static void
 406 split_sections (abfd, info)
 407      bfd *abfd;
 408      struct bfd_link_info *info;
 409 {
 410   asection *original_sec;
 411   int nsecs = abfd->section_count;
 412   sanity_check (abfd);
 413   /* look through all the original sections */
 414   for (original_sec = abfd->sections;
 415        original_sec && nsecs;
 416        original_sec = original_sec->next, nsecs--)
 417     {
 418       boolean first = true;
 419       int count = 0;
 420       int lines = 0;
 421       int relocs = 0;
 422       struct bfd_link_order **pp;
 423       bfd_vma vma = original_sec->vma;
 424       bfd_vma shift_offset = 0;
 425       asection *cursor = original_sec;
 426
 427       /* count up the relocations and line entries to see if
 428          anything would be too big to fit */
 429       for (pp = &(cursor->link_order_head); *pp; pp = &((*pp)->next))
 430         {
 431           struct bfd_link_order *p = *pp;
 432           int thislines = 0;
 433           int thisrelocs = 0;
 434           if (p->type == bfd_indirect_link_order)
 435             {
 436               asection *sec;
 437
 438               sec = p->u.indirect.section;
 439
 440               if (info->strip == strip_none
 441                   || info->strip == strip_some)
 442                 thislines = sec->lineno_count;
 443
 444               if (info->relocateable)
 445                 thisrelocs = sec->reloc_count;
 446
 447             }
 448           else if (info->relocateable
 449                    && (p->type == bfd_section_reloc_link_order
 450                        || p->type == bfd_symbol_reloc_link_order))
 451             thisrelocs++;
 452
 453           if (! first
 454               && (thisrelocs + relocs > config.split_by_reloc
 455                   || thislines + lines > config.split_by_reloc
 456                   || config.split_by_file))
 457             {
 458               /* create a new section and put this link order and the
 459                  following link orders into it */
 460               struct bfd_link_order *l = p;
 461               asection *n = clone_section (abfd, cursor, &count);
 462               *pp = NULL;       /* Snip off link orders from old section */
 463               n->link_order_head = l;   /* attach to new section */
 464               pp = &n->link_order_head;
 465
 466               /* change the size of the original section and
 467                  update the vma of the new one */
 468
 469               dump ("before snip", cursor, n);
 470
 471               n->_raw_size = cursor->_raw_size - l->offset;
 472               cursor->_raw_size = l->offset;
 473
 474               vma += cursor->_raw_size;
 475               n->lma = n->vma = vma;
 476
 477               shift_offset = l->offset;
 478
 479               /* run down the chain and change the output section to
 480                  the right one, update the offsets too */
 481
 482               while (l)
 483                 {
 484                   l->offset -= shift_offset;
 485                   if (l->type == bfd_indirect_link_order)
 486                     {
 487                       l->u.indirect.section->output_section = n;
 488                       l->u.indirect.section->output_offset = l->offset;
 489                     }
 490                   l = l->next;
 491                 }
 492               dump ("after snip", cursor, n);
 493               cursor = n;
 494               relocs = thisrelocs;
 495               lines = thislines;
 496             }
 497           else
 498             {
 499               relocs += thisrelocs;
 500               lines += thislines;
 501             }
 502
 503           first = false;
 504         }
 505     }
 506   sanity_check (abfd);
 507 }
 508 /**********************************************************************/
 509 void
 510 ldwrite ()
 511 {
 512   /* Reset error indicator, which can typically something like invalid
 513      format from openning up the .o files */
 514   bfd_set_error (bfd_error_no_error);
 515   lang_for_each_statement (build_link_order);
 516
 517   if (config.split_by_reloc || config.split_by_file)
 518     split_sections (output_bfd, &link_info);
 519   if (!bfd_final_link (output_bfd, &link_info))
 520     {
 521       /* If there was an error recorded, print it out.  Otherwise assume
 522          an appropriate error message like unknown symbol was printed
 523          out.  */
 524
 525       if (bfd_get_error () != bfd_error_no_error)
 526         einfo (_("%F%P: final link failed: %E\n"), output_bfd);
 527       else
 528         xexit(1);
 529     }
 530 }