source: trunk/src/binutils/bfd/coff-i386.c@ 402

Last change on this file since 402 was 10, checked in by bird, 23 years ago

Initial revision
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Line 
1/* BFD back-end for Intel 386 COFF files.
2 Copyright 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
3 2000, 2001
4 Free Software Foundation, Inc.
5 Written by Cygnus Support.
6
7This file is part of BFD, the Binary File Descriptor library.
8
9This program is free software; you can redistribute it and/or modify
10it under the terms of the GNU General Public License as published by
11the Free Software Foundation; either version 2 of the License, or
12(at your option) any later version.
13
14This program is distributed in the hope that it will be useful,
15but WITHOUT ANY WARRANTY; without even the implied warranty of
16MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17GNU General Public License for more details.
18
19You should have received a copy of the GNU General Public License
20along with this program; if not, write to the Free Software
21Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
22
23#include "bfd.h"
24#include "sysdep.h"
25#include "libbfd.h"
26
27#include "coff/i386.h"
28
29#include "coff/internal.h"
30
31#ifdef COFF_WITH_PE
32#include "coff/pe.h"
33#endif
34
35#ifdef COFF_GO32_EXE
36#include "coff/go32exe.h"
37#endif
38
39#include "libcoff.h"
40
41static bfd_reloc_status_type coff_i386_reloc
42 PARAMS ((bfd *, arelent *, asymbol *, PTR, asection *, bfd *, char **));
43static reloc_howto_type *coff_i386_rtype_to_howto
44 PARAMS ((bfd *, asection *, struct internal_reloc *,
45 struct coff_link_hash_entry *, struct internal_syment *,
46 bfd_vma *));
47static reloc_howto_type *coff_i386_reloc_type_lookup
48 PARAMS ((bfd *, bfd_reloc_code_real_type));
49
50#define COFF_DEFAULT_SECTION_ALIGNMENT_POWER (2)
51/* The page size is a guess based on ELF. */
52
53#define COFF_PAGE_SIZE 0x1000
54
55/* For some reason when using i386 COFF the value stored in the .text
56 section for a reference to a common symbol is the value itself plus
57 any desired offset. Ian Taylor, Cygnus Support. */
58
59/* If we are producing relocateable output, we need to do some
60 adjustments to the object file that are not done by the
61 bfd_perform_relocation function. This function is called by every
62 reloc type to make any required adjustments. */
63
64static bfd_reloc_status_type
65coff_i386_reloc (abfd, reloc_entry, symbol, data, input_section, output_bfd,
66 error_message)
67 bfd *abfd;
68 arelent *reloc_entry;
69 asymbol *symbol;
70 PTR data;
71 asection *input_section ATTRIBUTE_UNUSED;
72 bfd *output_bfd;
73 char **error_message ATTRIBUTE_UNUSED;
74{
75 symvalue diff;
76
77#ifndef COFF_WITH_PE
78 if (output_bfd == (bfd *) NULL)
79 return bfd_reloc_continue;
80#endif
81
82 if (bfd_is_com_section (symbol->section))
83 {
84#ifndef COFF_WITH_PE
85 /* We are relocating a common symbol. The current value in the
86 object file is ORIG + OFFSET, where ORIG is the value of the
87 common symbol as seen by the object file when it was compiled
88 (this may be zero if the symbol was undefined) and OFFSET is
89 the offset into the common symbol (normally zero, but may be
90 non-zero when referring to a field in a common structure).
91 ORIG is the negative of reloc_entry->addend, which is set by
92 the CALC_ADDEND macro below. We want to replace the value in
93 the object file with NEW + OFFSET, where NEW is the value of
94 the common symbol which we are going to put in the final
95 object file. NEW is symbol->value. */
96 diff = symbol->value + reloc_entry->addend;
97#else
98 /* In PE mode, we do not offset the common symbol. */
99 diff = reloc_entry->addend;
100#endif
101 }
102 else
103 {
104 /* For some reason bfd_perform_relocation always effectively
105 ignores the addend for a COFF target when producing
106 relocateable output. This seems to be always wrong for 386
107 COFF, so we handle the addend here instead. */
108#ifdef COFF_WITH_PE
109 if (output_bfd == (bfd *) NULL)
110 {
111 reloc_howto_type *howto = reloc_entry->howto;
112
113 /* Although PC relative relocations are very similar between
114 PE and non-PE formats, but they are off by 1 << howto->size
115 bytes. For the external relocation, PE is very different
116 from others. See md_apply_fix3 () in gas/config/tc-i386.c.
117 When we link PE and non-PE object files together to
118 generate a non-PE executable, we have to compensate it
119 here. */
120 if (howto->pc_relative == true && howto->pcrel_offset == true)
121 diff = -(1 << howto->size);
122 else
123 diff = -reloc_entry->addend;
124 }
125 else
126#endif
127 diff = reloc_entry->addend;
128 }
129
130#ifdef COFF_WITH_PE
131 /* FIXME: How should this case be handled? */
132 if (reloc_entry->howto->type == R_IMAGEBASE
133 && output_bfd != NULL
134 && bfd_get_flavour(output_bfd) == bfd_target_coff_flavour)
135 diff -= pe_data (output_bfd)->pe_opthdr.ImageBase;
136#endif
137
138#define DOIT(x) \
139 x = ((x & ~howto->dst_mask) | (((x & howto->src_mask) + diff) & howto->dst_mask))
140
141 if (diff != 0)
142 {
143 reloc_howto_type *howto = reloc_entry->howto;
144 unsigned char *addr = (unsigned char *) data + reloc_entry->address;
145
146 switch (howto->size)
147 {
148 case 0:
149 {
150 char x = bfd_get_8 (abfd, addr);
151 DOIT (x);
152 bfd_put_8 (abfd, x, addr);
153 }
154 break;
155
156 case 1:
157 {
158 short x = bfd_get_16 (abfd, addr);
159 DOIT (x);
160 bfd_put_16 (abfd, x, addr);
161 }
162 break;
163
164 case 2:
165 {
166 long x = bfd_get_32 (abfd, addr);
167 DOIT (x);
168 bfd_put_32 (abfd, x, addr);
169 }
170 break;
171
172 default:
173 abort ();
174 }
175 }
176
177 /* Now let bfd_perform_relocation finish everything up. */
178 return bfd_reloc_continue;
179}
180
181#ifdef COFF_WITH_PE
182/* Return true if this relocation should appear in the output .reloc
183 section. */
184
185static boolean in_reloc_p PARAMS ((bfd *, reloc_howto_type *));
186
187static boolean in_reloc_p (abfd, howto)
188 bfd * abfd ATTRIBUTE_UNUSED;
189 reloc_howto_type *howto;
190{
191 return ! howto->pc_relative && howto->type != R_IMAGEBASE;
192}
193#endif /* COFF_WITH_PE */
194
195#ifndef PCRELOFFSET
196#define PCRELOFFSET false
197#endif
198
199static reloc_howto_type howto_table[] =
200{
201 EMPTY_HOWTO (0),
202 EMPTY_HOWTO (1),
203 EMPTY_HOWTO (2),
204 EMPTY_HOWTO (3),
205 EMPTY_HOWTO (4),
206 EMPTY_HOWTO (5),
207 HOWTO (R_DIR32, /* type */
208 0, /* rightshift */
209 2, /* size (0 = byte, 1 = short, 2 = long) */
210 32, /* bitsize */
211 false, /* pc_relative */
212 0, /* bitpos */
213 complain_overflow_bitfield, /* complain_on_overflow */
214 coff_i386_reloc, /* special_function */
215 "dir32", /* name */
216 true, /* partial_inplace */
217 0xffffffff, /* src_mask */
218 0xffffffff, /* dst_mask */
219 true), /* pcrel_offset */
220 /* PE IMAGE_REL_I386_DIR32NB relocation (7). */
221 HOWTO (R_IMAGEBASE, /* type */
222 0, /* rightshift */
223 2, /* size (0 = byte, 1 = short, 2 = long) */
224 32, /* bitsize */
225 false, /* pc_relative */
226 0, /* bitpos */
227 complain_overflow_bitfield, /* complain_on_overflow */
228 coff_i386_reloc, /* special_function */
229 "rva32", /* name */
230 true, /* partial_inplace */
231 0xffffffff, /* src_mask */
232 0xffffffff, /* dst_mask */
233 false), /* pcrel_offset */
234 EMPTY_HOWTO (010),
235 EMPTY_HOWTO (011),
236 EMPTY_HOWTO (012),
237 EMPTY_HOWTO (013),
238 EMPTY_HOWTO (014),
239 EMPTY_HOWTO (015),
240 EMPTY_HOWTO (016),
241 /* Byte relocation (017). */
242 HOWTO (R_RELBYTE, /* type */
243 0, /* rightshift */
244 0, /* size (0 = byte, 1 = short, 2 = long) */
245 8, /* bitsize */
246 false, /* pc_relative */
247 0, /* bitpos */
248 complain_overflow_bitfield, /* complain_on_overflow */
249 coff_i386_reloc, /* special_function */
250 "8", /* name */
251 true, /* partial_inplace */
252 0x000000ff, /* src_mask */
253 0x000000ff, /* dst_mask */
254 PCRELOFFSET), /* pcrel_offset */
255 /* 16-bit word relocation (020). */
256 HOWTO (R_RELWORD, /* type */
257 0, /* rightshift */
258 1, /* size (0 = byte, 1 = short, 2 = long) */
259 16, /* bitsize */
260 false, /* pc_relative */
261 0, /* bitpos */
262 complain_overflow_bitfield, /* complain_on_overflow */
263 coff_i386_reloc, /* special_function */
264 "16", /* name */
265 true, /* partial_inplace */
266 0x0000ffff, /* src_mask */
267 0x0000ffff, /* dst_mask */
268 PCRELOFFSET), /* pcrel_offset */
269 /* 32-bit longword relocation (021). */
270 HOWTO (R_RELLONG, /* type */
271 0, /* rightshift */
272 2, /* size (0 = byte, 1 = short, 2 = long) */
273 32, /* bitsize */
274 false, /* pc_relative */
275 0, /* bitpos */
276 complain_overflow_bitfield, /* complain_on_overflow */
277 coff_i386_reloc, /* special_function */
278 "32", /* name */
279 true, /* partial_inplace */
280 0xffffffff, /* src_mask */
281 0xffffffff, /* dst_mask */
282 PCRELOFFSET), /* pcrel_offset */
283 /* Byte PC relative relocation (022). */
284 HOWTO (R_PCRBYTE, /* type */
285 0, /* rightshift */
286 0, /* size (0 = byte, 1 = short, 2 = long) */
287 8, /* bitsize */
288 true, /* pc_relative */
289 0, /* bitpos */
290 complain_overflow_signed, /* complain_on_overflow */
291 coff_i386_reloc, /* special_function */
292 "DISP8", /* name */
293 true, /* partial_inplace */
294 0x000000ff, /* src_mask */
295 0x000000ff, /* dst_mask */
296 PCRELOFFSET), /* pcrel_offset */
297 /* 16-bit word PC relative relocation (023). */
298 HOWTO (R_PCRWORD, /* type */
299 0, /* rightshift */
300 1, /* size (0 = byte, 1 = short, 2 = long) */
301 16, /* bitsize */
302 true, /* pc_relative */
303 0, /* bitpos */
304 complain_overflow_signed, /* complain_on_overflow */
305 coff_i386_reloc, /* special_function */
306 "DISP16", /* name */
307 true, /* partial_inplace */
308 0x0000ffff, /* src_mask */
309 0x0000ffff, /* dst_mask */
310 PCRELOFFSET), /* pcrel_offset */
311 /* 32-bit longword PC relative relocation (024). */
312 HOWTO (R_PCRLONG, /* type */
313 0, /* rightshift */
314 2, /* size (0 = byte, 1 = short, 2 = long) */
315 32, /* bitsize */
316 true, /* pc_relative */
317 0, /* bitpos */
318 complain_overflow_signed, /* complain_on_overflow */
319 coff_i386_reloc, /* special_function */
320 "DISP32", /* name */
321 true, /* partial_inplace */
322 0xffffffff, /* src_mask */
323 0xffffffff, /* dst_mask */
324 PCRELOFFSET) /* pcrel_offset */
325};
326
327/* Turn a howto into a reloc nunmber */
328
329#define SELECT_RELOC(x,howto) { x.r_type = howto->type; }
330#define BADMAG(x) I386BADMAG(x)
331#define I386 1 /* Customize coffcode.h */
332
333#define RTYPE2HOWTO(cache_ptr, dst) \
334 ((cache_ptr)->howto = \
335 ((dst)->r_type < sizeof (howto_table) / sizeof (howto_table[0]) \
336 ? howto_table + (dst)->r_type \
337 : NULL))
338
339/* For 386 COFF a STYP_NOLOAD | STYP_BSS section is part of a shared
340 library. On some other COFF targets STYP_BSS is normally
341 STYP_NOLOAD. */
342#define BSS_NOLOAD_IS_SHARED_LIBRARY
343
344/* Compute the addend of a reloc. If the reloc is to a common symbol,
345 the object file contains the value of the common symbol. By the
346 time this is called, the linker may be using a different symbol
347 from a different object file with a different value. Therefore, we
348 hack wildly to locate the original symbol from this file so that we
349 can make the correct adjustment. This macro sets coffsym to the
350 symbol from the original file, and uses it to set the addend value
351 correctly. If this is not a common symbol, the usual addend
352 calculation is done, except that an additional tweak is needed for
353 PC relative relocs.
354 FIXME: This macro refers to symbols and asect; these are from the
355 calling function, not the macro arguments. */
356
357#define CALC_ADDEND(abfd, ptr, reloc, cache_ptr) \
358 { \
359 coff_symbol_type *coffsym = (coff_symbol_type *) NULL; \
360 if (ptr && bfd_asymbol_bfd (ptr) != abfd) \
361 coffsym = (obj_symbols (abfd) \
362 + (cache_ptr->sym_ptr_ptr - symbols)); \
363 else if (ptr) \
364 coffsym = coff_symbol_from (abfd, ptr); \
365 if (coffsym != (coff_symbol_type *) NULL \
366 && coffsym->native->u.syment.n_scnum == 0) \
367 cache_ptr->addend = - coffsym->native->u.syment.n_value; \
368 else if (ptr && bfd_asymbol_bfd (ptr) == abfd \
369 && ptr->section != (asection *) NULL) \
370 cache_ptr->addend = - (ptr->section->vma + ptr->value); \
371 else \
372 cache_ptr->addend = 0; \
373 if (ptr && howto_table[reloc.r_type].pc_relative) \
374 cache_ptr->addend += asect->vma; \
375 }
376
377/* We use the special COFF backend linker. For normal i386 COFF, we
378 can use the generic relocate_section routine. For PE, we need our
379 own routine. */
380
381#ifndef COFF_WITH_PE
382
383#define coff_relocate_section _bfd_coff_generic_relocate_section
384
385#else /* COFF_WITH_PE */
386
387/* The PE relocate section routine. The only difference between this
388 and the regular routine is that we don't want to do anything for a
389 relocateable link. */
390
391static boolean coff_pe_i386_relocate_section
392 PARAMS ((bfd *, struct bfd_link_info *, bfd *, asection *, bfd_byte *,
393 struct internal_reloc *, struct internal_syment *, asection **));
394
395static boolean
396coff_pe_i386_relocate_section (output_bfd, info, input_bfd,
397 input_section, contents, relocs, syms,
398 sections)
399 bfd *output_bfd;
400 struct bfd_link_info *info;
401 bfd *input_bfd;
402 asection *input_section;
403 bfd_byte *contents;
404 struct internal_reloc *relocs;
405 struct internal_syment *syms;
406 asection **sections;
407{
408 if (info->relocateable)
409 return true;
410
411 return _bfd_coff_generic_relocate_section (output_bfd, info, input_bfd,
412 input_section, contents,
413 relocs, syms, sections);
414}
415
416#define coff_relocate_section coff_pe_i386_relocate_section
417
418#endif /* COFF_WITH_PE */
419
420/* Convert an rtype to howto for the COFF backend linker. */
421
422static reloc_howto_type *
423coff_i386_rtype_to_howto (abfd, sec, rel, h, sym, addendp)
424 bfd *abfd ATTRIBUTE_UNUSED;
425 asection *sec;
426 struct internal_reloc *rel;
427 struct coff_link_hash_entry *h;
428 struct internal_syment *sym;
429 bfd_vma *addendp;
430{
431 reloc_howto_type *howto;
432
433 if (rel->r_type > sizeof (howto_table) / sizeof (howto_table[0]))
434 {
435 bfd_set_error (bfd_error_bad_value);
436 return NULL;
437 }
438
439 howto = howto_table + rel->r_type;
440
441#ifdef COFF_WITH_PE
442 /* Cancel out code in _bfd_coff_generic_relocate_section. */
443 *addendp = 0;
444#endif
445
446 if (howto->pc_relative)
447 *addendp += sec->vma;
448
449 if (sym != NULL && sym->n_scnum == 0 && sym->n_value != 0)
450 {
451 /* This is a common symbol. The section contents include the
452 size (sym->n_value) as an addend. The relocate_section
453 function will be adding in the final value of the symbol. We
454 need to subtract out the current size in order to get the
455 correct result. */
456
457 BFD_ASSERT (h != NULL);
458
459#ifndef COFF_WITH_PE
460 /* I think we *do* want to bypass this. If we don't, I have
461 seen some data parameters get the wrong relocation address.
462 If I link two versions with and without this section bypassed
463 and then do a binary comparison, the addresses which are
464 different can be looked up in the map. The case in which
465 this section has been bypassed has addresses which correspond
466 to values I can find in the map. */
467 *addendp -= sym->n_value;
468#endif
469 }
470
471#ifndef COFF_WITH_PE
472 /* If the output symbol is common (in which case this must be a
473 relocateable link), we need to add in the final size of the
474 common symbol. */
475 if (h != NULL && h->root.type == bfd_link_hash_common)
476 *addendp += h->root.u.c.size;
477#endif
478
479#ifdef COFF_WITH_PE
480 if (howto->pc_relative)
481 {
482 *addendp -= 4;
483
484 /* If the symbol is defined, then the generic code is going to
485 add back the symbol value in order to cancel out an
486 adjustment it made to the addend. However, we set the addend
487 to 0 at the start of this function. We need to adjust here,
488 to avoid the adjustment the generic code will make. FIXME:
489 This is getting a bit hackish. */
490 if (sym != NULL && sym->n_scnum != 0)
491 *addendp -= sym->n_value;
492 }
493
494 if (rel->r_type == R_IMAGEBASE
495 && (bfd_get_flavour(sec->output_section->owner)
496 == bfd_target_coff_flavour))
497 {
498 *addendp -= pe_data(sec->output_section->owner)->pe_opthdr.ImageBase;
499 }
500#endif
501
502 return howto;
503}
504
505#define coff_bfd_reloc_type_lookup coff_i386_reloc_type_lookup
506
507static reloc_howto_type *
508coff_i386_reloc_type_lookup (abfd, code)
509 bfd *abfd ATTRIBUTE_UNUSED;
510 bfd_reloc_code_real_type code;
511{
512 switch (code)
513 {
514 case BFD_RELOC_RVA:
515 return howto_table + R_IMAGEBASE;
516 case BFD_RELOC_32:
517 return howto_table + R_DIR32;
518 case BFD_RELOC_32_PCREL:
519 return howto_table + R_PCRLONG;
520 case BFD_RELOC_16:
521 return howto_table + R_RELWORD;
522 case BFD_RELOC_16_PCREL:
523 return howto_table + R_PCRWORD;
524 case BFD_RELOC_8:
525 return howto_table + R_RELBYTE;
526 case BFD_RELOC_8_PCREL:
527 return howto_table + R_PCRBYTE;
528 default:
529 BFD_FAIL ();
530 return 0;
531 }
532}
533
534#define coff_rtype_to_howto coff_i386_rtype_to_howto
535
536#ifdef TARGET_UNDERSCORE
537
538/* If i386 gcc uses underscores for symbol names, then it does not use
539 a leading dot for local labels, so if TARGET_UNDERSCORE is defined
540 we treat all symbols starting with L as local. */
541
542static boolean coff_i386_is_local_label_name PARAMS ((bfd *, const char *));
543
544static boolean
545coff_i386_is_local_label_name (abfd, name)
546 bfd *abfd;
547 const char *name;
548{
549 if (name[0] == 'L')
550 return true;
551
552 return _bfd_coff_is_local_label_name (abfd, name);
553}
554
555#define coff_bfd_is_local_label_name coff_i386_is_local_label_name
556
557#endif /* TARGET_UNDERSCORE */
558
559#include "coffcode.h"
560
561const bfd_target
562#ifdef TARGET_SYM
563 TARGET_SYM =
564#else
565 i386coff_vec =
566#endif
567{
568#ifdef TARGET_NAME
569 TARGET_NAME,
570#else
571 "coff-i386", /* name */
572#endif
573 bfd_target_coff_flavour,
574 BFD_ENDIAN_LITTLE, /* data byte order is little */
575 BFD_ENDIAN_LITTLE, /* header byte order is little */
576
577 (HAS_RELOC | EXEC_P | /* object flags */
578 HAS_LINENO | HAS_DEBUG |
579 HAS_SYMS | HAS_LOCALS | WP_TEXT | D_PAGED),
580
581 (SEC_HAS_CONTENTS | SEC_ALLOC | SEC_LOAD | SEC_RELOC /* section flags */
582#ifdef COFF_WITH_PE
583 | SEC_LINK_ONCE | SEC_LINK_DUPLICATES | SEC_READONLY
584#endif
585 | SEC_CODE | SEC_DATA),
586
587#ifdef TARGET_UNDERSCORE
588 TARGET_UNDERSCORE, /* leading underscore */
589#else
590 0, /* leading underscore */
591#endif
592 '/', /* ar_pad_char */
593 15, /* ar_max_namelen */
594
595 bfd_getl64, bfd_getl_signed_64, bfd_putl64,
596 bfd_getl32, bfd_getl_signed_32, bfd_putl32,
597 bfd_getl16, bfd_getl_signed_16, bfd_putl16, /* data */
598 bfd_getl64, bfd_getl_signed_64, bfd_putl64,
599 bfd_getl32, bfd_getl_signed_32, bfd_putl32,
600 bfd_getl16, bfd_getl_signed_16, bfd_putl16, /* hdrs */
601
602/* Note that we allow an object file to be treated as a core file as well. */
603 {_bfd_dummy_target, coff_object_p, /* bfd_check_format */
604 bfd_generic_archive_p, coff_object_p},
605 {bfd_false, coff_mkobject, _bfd_generic_mkarchive, /* bfd_set_format */
606 bfd_false},
607 {bfd_false, coff_write_object_contents, /* bfd_write_contents */
608 _bfd_write_archive_contents, bfd_false},
609
610 BFD_JUMP_TABLE_GENERIC (coff),
611 BFD_JUMP_TABLE_COPY (coff),
612 BFD_JUMP_TABLE_CORE (_bfd_nocore),
613 BFD_JUMP_TABLE_ARCHIVE (_bfd_archive_coff),
614 BFD_JUMP_TABLE_SYMBOLS (coff),
615 BFD_JUMP_TABLE_RELOCS (coff),
616 BFD_JUMP_TABLE_WRITE (coff),
617 BFD_JUMP_TABLE_LINK (coff),
618 BFD_JUMP_TABLE_DYNAMIC (_bfd_nodynamic),
619
620 NULL,
621
622 COFF_SWAP_TABLE
623};
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