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[binutils-gdb.git] / bfd / m68klinux.c
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1 /* BFD back-end for linux flavored m68k a.out binaries.
2 Copyright (C) 1992-2017 Free Software Foundation, Inc.
4 This file is part of BFD, the Binary File Descriptor library.
6 This program is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 3 of the License, or
9 (at your option) any later version.
11 This program is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with this program; if not, write to the Free Software
18 Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
19 MA 02110-1301, USA. */
21 #define TARGET_PAGE_SIZE 4096
22 #define ZMAGIC_DISK_BLOCK_SIZE 1024
23 #define SEGMENT_SIZE TARGET_PAGE_SIZE
24 #define TEXT_START_ADDR 0x0
26 #define MACHTYPE_OK(mtype) ((mtype) == M_68020 || (mtype) == M_UNKNOWN)
28 #include "sysdep.h"
29 #include "bfd.h"
30 #include "libbfd.h"
31 #include "aout/aout64.h"
32 #include "aout/stab_gnu.h"
33 #include "aout/ar.h"
34 #include "libaout.h" /* BFD a.out internal data structures */
36 #define TARGET_IS_BIG_ENDIAN_P
37 #define DEFAULT_ARCH bfd_arch_m68k
39 /* Do not "beautify" the CONCAT* macro args. Traditional C will not
40 remove whitespace added here, and thus will fail to concatenate
41 the tokens. */
42 #define MY(OP) CONCAT2 (m68k_aout_linux_,OP)
43 #define TARGETNAME "a.out-m68k-linux"
45 extern const bfd_target MY(vec);
47 /* We always generate QMAGIC files in preference to ZMAGIC files. It
48 would be possible to make this a linker option, if that ever
49 becomes important. */
51 static void MY_final_link_callback
52 (bfd *, file_ptr *, file_ptr *, file_ptr *);
54 static bfd_boolean
55 m68klinux_bfd_final_link (bfd *abfd,
56 struct bfd_link_info *info)
58 obj_aout_subformat (abfd) = q_magic_format;
59 return NAME(aout,final_link) (abfd, info, MY_final_link_callback);
62 #define MY_bfd_final_link m68klinux_bfd_final_link
64 /* Set the machine type correctly. */
66 static bfd_boolean
67 m68klinux_write_object_contents (bfd *abfd)
69 struct external_exec exec_bytes;
70 struct internal_exec *execp = exec_hdr (abfd);
72 N_SET_MACHTYPE (execp, M_68020);
74 obj_reloc_entry_size (abfd) = RELOC_STD_SIZE;
76 WRITE_HEADERS (abfd, execp);
78 return TRUE;
81 #define MY_write_object_contents m68klinux_write_object_contents
83 /* Code to link against Linux a.out shared libraries. */
85 /* See if a symbol name is a reference to the global offset table. */
87 #ifndef GOT_REF_PREFIX
88 #define GOT_REF_PREFIX "__GOT_"
89 #endif
91 #define IS_GOT_SYM(name) (CONST_STRNEQ (name, GOT_REF_PREFIX))
93 /* See if a symbol name is a reference to the procedure linkage table. */
95 #ifndef PLT_REF_PREFIX
96 #define PLT_REF_PREFIX "__PLT_"
97 #endif
99 #define IS_PLT_SYM(name) (CONST_STRNEQ (name, PLT_REF_PREFIX))
101 /* This string is used to generate specialized error messages. */
103 #ifndef NEEDS_SHRLIB
104 #define NEEDS_SHRLIB "__NEEDS_SHRLIB_"
105 #endif
107 /* This special symbol is a set vector that contains a list of
108 pointers to fixup tables. It will be present in any dynamically
109 linked file. The linker generated fixup table should also be added
110 to the list, and it should always appear in the second slot (the
111 first one is a dummy with a magic number that is defined in
112 crt0.o). */
114 #ifndef SHARABLE_CONFLICTS
115 #define SHARABLE_CONFLICTS "__SHARABLE_CONFLICTS__"
116 #endif
118 /* We keep a list of fixups. The terminology is a bit strange, but
119 each fixup contains two 32 bit numbers. A regular fixup contains
120 an address and a pointer, and at runtime we should store the
121 address at the location pointed to by the pointer. A builtin fixup
122 contains two pointers, and we should read the address using one
123 pointer and store it at the location pointed to by the other
124 pointer. Builtin fixups come into play when we have duplicate
125 __GOT__ symbols for the same variable. The builtin fixup will copy
126 the GOT pointer from one over into the other. */
128 struct fixup
130 struct fixup *next;
131 struct linux_link_hash_entry *h;
132 bfd_vma value;
134 /* Nonzero if this is a jump instruction that needs to be fixed,
135 zero if this is just a pointer */
136 char jump;
138 char builtin;
141 /* We don't need a special hash table entry structure, but we do need
142 to keep some information between linker passes, so we use a special
143 hash table. */
145 struct linux_link_hash_entry
147 struct aout_link_hash_entry root;
150 struct linux_link_hash_table
152 struct aout_link_hash_table root;
154 /* First dynamic object found in link. */
155 bfd *dynobj;
157 /* Number of fixups. */
158 size_t fixup_count;
160 /* Number of builtin fixups. */
161 size_t local_builtins;
163 /* List of fixups. */
164 struct fixup *fixup_list;
167 /* Routine to create an entry in an Linux link hash table. */
169 static struct bfd_hash_entry *
170 linux_link_hash_newfunc (struct bfd_hash_entry *entry,
171 struct bfd_hash_table *table,
172 const char *string)
174 struct linux_link_hash_entry *ret = (struct linux_link_hash_entry *) entry;
176 /* Allocate the structure if it has not already been allocated by a
177 subclass. */
178 if (ret == (struct linux_link_hash_entry *) NULL)
179 ret = ((struct linux_link_hash_entry *)
180 bfd_hash_allocate (table, sizeof (struct linux_link_hash_entry)));
181 if (ret == NULL)
182 return (struct bfd_hash_entry *) ret;
184 /* Call the allocation method of the superclass. */
185 ret = ((struct linux_link_hash_entry *)
186 NAME(aout,link_hash_newfunc) ((struct bfd_hash_entry *) ret,
187 table, string));
188 if (ret != NULL)
190 /* Set local fields; there aren't any. */
193 return (struct bfd_hash_entry *) ret;
196 /* Create a Linux link hash table. */
198 static struct bfd_link_hash_table *
199 linux_link_hash_table_create (bfd *abfd)
201 struct linux_link_hash_table *ret;
202 bfd_size_type amt = sizeof (struct linux_link_hash_table);
204 ret = (struct linux_link_hash_table *) bfd_zmalloc (amt);
205 if (ret == (struct linux_link_hash_table *) NULL)
207 bfd_set_error (bfd_error_no_memory);
208 return (struct bfd_link_hash_table *) NULL;
210 if (!NAME(aout,link_hash_table_init) (&ret->root, abfd,
211 linux_link_hash_newfunc,
212 sizeof (struct linux_link_hash_entry)))
214 free (ret);
215 return (struct bfd_link_hash_table *) NULL;
218 return &ret->root.root;
221 /* Look up an entry in a Linux link hash table. */
223 #define linux_link_hash_lookup(table, string, create, copy, follow) \
224 ((struct linux_link_hash_entry *) \
225 aout_link_hash_lookup (&(table)->root, (string), (create), (copy),\
226 (follow)))
228 /* Traverse a Linux link hash table. */
230 #define linux_link_hash_traverse(table, func, info) \
231 (aout_link_hash_traverse \
232 (&(table)->root, \
233 (bfd_boolean (*) (struct aout_link_hash_entry *, void *)) (func), \
234 (info)))
236 /* Get the Linux link hash table from the info structure. This is
237 just a cast. */
239 #define linux_hash_table(p) ((struct linux_link_hash_table *) ((p)->hash))
241 /* Store the information for a new fixup. */
243 static struct fixup *
244 new_fixup (struct bfd_link_info *info,
245 struct linux_link_hash_entry *h,
246 bfd_vma value,
247 int builtin)
249 struct fixup *f;
251 f = (struct fixup *) bfd_hash_allocate (&info->hash->table,
252 sizeof (struct fixup));
253 if (f == NULL)
254 return f;
255 f->next = linux_hash_table (info)->fixup_list;
256 linux_hash_table (info)->fixup_list = f;
257 f->h = h;
258 f->value = value;
259 f->builtin = builtin;
260 f->jump = 0;
261 ++linux_hash_table (info)->fixup_count;
262 return f;
265 /* We come here once we realize that we are going to link to a shared
266 library. We need to create a special section that contains the
267 fixup table, and we ultimately need to add a pointer to this into
268 the set vector for SHARABLE_CONFLICTS. At this point we do not
269 know the size of the section, but that's OK - we just need to
270 create it for now. */
272 static bfd_boolean
273 linux_link_create_dynamic_sections (bfd *abfd,
274 struct bfd_link_info *info ATTRIBUTE_UNUSED)
276 flagword flags;
277 asection *s;
279 /* Note that we set the SEC_IN_MEMORY flag. */
280 flags = SEC_ALLOC | SEC_LOAD | SEC_HAS_CONTENTS | SEC_IN_MEMORY;
282 /* We choose to use the name ".linux-dynamic" for the fixup table.
283 Why not? */
284 s = bfd_make_section_with_flags (abfd, ".linux-dynamic", flags);
285 if (s == NULL
286 || ! bfd_set_section_alignment (abfd, s, 2))
287 return FALSE;
288 s->size = 0;
289 s->contents = 0;
291 return TRUE;
294 /* Function to add a single symbol to the linker hash table. This is
295 a wrapper around _bfd_generic_link_add_one_symbol which handles the
296 tweaking needed for dynamic linking support. */
298 static bfd_boolean
299 linux_add_one_symbol (struct bfd_link_info *info,
300 bfd *abfd,
301 const char *name,
302 flagword flags,
303 asection *section,
304 bfd_vma value,
305 const char *string,
306 bfd_boolean copy,
307 bfd_boolean collect,
308 struct bfd_link_hash_entry **hashp)
310 struct linux_link_hash_entry *h;
311 bfd_boolean insert;
313 /* Look up and see if we already have this symbol in the hash table.
314 If we do, and the defining entry is from a shared library, we
315 need to create the dynamic sections.
317 FIXME: What if abfd->xvec != info->output_bfd->xvec? We may
318 want to be able to link Linux a.out and ELF objects together,
319 but serious confusion is possible. */
321 insert = FALSE;
323 if (! bfd_link_relocatable (info)
324 && linux_hash_table (info)->dynobj == NULL
325 && strcmp (name, SHARABLE_CONFLICTS) == 0
326 && (flags & BSF_CONSTRUCTOR) != 0
327 && abfd->xvec == info->output_bfd->xvec)
329 if (! linux_link_create_dynamic_sections (abfd, info))
330 return FALSE;
331 linux_hash_table (info)->dynobj = abfd;
332 insert = TRUE;
335 if (bfd_is_abs_section (section)
336 && abfd->xvec == info->output_bfd->xvec)
338 h = linux_link_hash_lookup (linux_hash_table (info), name, FALSE,
339 FALSE, FALSE);
340 if (h != NULL
341 && (h->root.root.type == bfd_link_hash_defined
342 || h->root.root.type == bfd_link_hash_defweak))
344 struct fixup *f;
346 if (hashp != NULL)
347 *hashp = (struct bfd_link_hash_entry *) h;
349 f = new_fixup (info, h, value, ! IS_PLT_SYM (name));
350 if (f == NULL)
351 return FALSE;
352 f->jump = IS_PLT_SYM (name);
354 return TRUE;
358 /* Do the usual procedure for adding a symbol. */
359 if (! _bfd_generic_link_add_one_symbol (info, abfd, name, flags, section,
360 value, string, copy, collect,
361 hashp))
362 return FALSE;
364 /* Insert a pointer to our table in the set vector. The dynamic
365 linker requires this information */
366 if (insert)
368 asection *s;
370 /* Here we do our special thing to add the pointer to the
371 dynamic section in the SHARABLE_CONFLICTS set vector. */
372 s = bfd_get_section_by_name (linux_hash_table (info)->dynobj,
373 ".linux-dynamic");
374 BFD_ASSERT (s != NULL);
376 if (! (_bfd_generic_link_add_one_symbol
377 (info, linux_hash_table (info)->dynobj, SHARABLE_CONFLICTS,
378 BSF_GLOBAL | BSF_CONSTRUCTOR, s, (bfd_vma) 0, NULL,
379 FALSE, FALSE, NULL)))
380 return FALSE;
383 return TRUE;
386 /* We will crawl the hash table and come here for every global symbol.
387 We will examine each entry and see if there are indications that we
388 need to add a fixup. There are two possible cases - one is where
389 you have duplicate definitions of PLT or GOT symbols - these will
390 have already been caught and added as "builtin" fixups. If we find
391 that the corresponding non PLT/GOT symbol is also present, we
392 convert it to a regular fixup instead.
394 This function is called via linux_link_hash_traverse. */
396 static bfd_boolean
397 linux_tally_symbols (struct linux_link_hash_entry *h,
398 void * data)
400 struct bfd_link_info *info = (struct bfd_link_info *) data;
401 struct fixup *f, *f1;
402 int is_plt;
403 struct linux_link_hash_entry *h1, *h2;
404 bfd_boolean exists;
406 if (h->root.root.type == bfd_link_hash_undefined
407 && CONST_STRNEQ (h->root.root.root.string, NEEDS_SHRLIB))
409 const char *name;
410 char *p;
411 char *alloc = NULL;
413 name = h->root.root.root.string + sizeof NEEDS_SHRLIB - 1;
414 p = strrchr (name, '_');
415 if (p != NULL)
416 alloc = (char *) bfd_malloc ((bfd_size_type) strlen (name) + 1);
418 if (p == NULL || alloc == NULL)
419 _bfd_error_handler (_("Output file requires shared library `%s'\n"),
420 name);
421 else
423 strcpy (alloc, name);
424 p = strrchr (alloc, '_');
425 *p++ = '\0';
426 _bfd_error_handler
427 /* xgettext:c-format */
428 (_("Output file requires shared library `%s.so.%s'\n"),
429 alloc, p);
430 free (alloc);
433 abort ();
436 /* If this symbol is not a PLT/GOT, we do not even need to look at it */
437 is_plt = IS_PLT_SYM (h->root.root.root.string);
439 if (is_plt || IS_GOT_SYM (h->root.root.root.string))
441 /* Look up this symbol twice. Once just as a regular lookup,
442 and then again following all of the indirect links until we
443 reach a real symbol. */
444 h1 = linux_link_hash_lookup (linux_hash_table (info),
445 (h->root.root.root.string
446 + sizeof PLT_REF_PREFIX - 1),
447 FALSE, FALSE, TRUE);
448 /* h2 does not follow indirect symbols. */
449 h2 = linux_link_hash_lookup (linux_hash_table (info),
450 (h->root.root.root.string
451 + sizeof PLT_REF_PREFIX - 1),
452 FALSE, FALSE, FALSE);
454 /* The real symbol must exist but if it is also an ABS symbol,
455 there is no need to have a fixup. This is because they both
456 came from the same library. If on the other hand, we had to
457 use an indirect symbol to get to the real symbol, we add the
458 fixup anyway, since there are cases where these symbols come
459 from different shared libraries */
460 if (h1 != NULL
461 && (((h1->root.root.type == bfd_link_hash_defined
462 || h1->root.root.type == bfd_link_hash_defweak)
463 && ! bfd_is_abs_section (h1->root.root.u.def.section))
464 || h2->root.root.type == bfd_link_hash_indirect))
466 /* See if there is a "builtin" fixup already present
467 involving this symbol. If so, convert it to a regular
468 fixup. In the end, this relaxes some of the requirements
469 about the order of performing fixups. */
470 exists = FALSE;
471 for (f1 = linux_hash_table (info)->fixup_list;
472 f1 != NULL;
473 f1 = f1->next)
475 if ((f1->h != h && f1->h != h1)
476 || (! f1->builtin && ! f1->jump))
477 continue;
478 if (f1->h == h1)
479 exists = TRUE;
480 if (! exists
481 && bfd_is_abs_section (h->root.root.u.def.section))
483 f = new_fixup (info, h1, f1->h->root.root.u.def.value, 0);
484 f->jump = is_plt;
486 f1->h = h1;
487 f1->jump = is_plt;
488 f1->builtin = 0;
489 exists = TRUE;
491 if (! exists
492 && bfd_is_abs_section (h->root.root.u.def.section))
494 f = new_fixup (info, h1, h->root.root.u.def.value, 0);
495 if (f == NULL)
497 /* FIXME: No way to return error. */
498 abort ();
500 f->jump = is_plt;
504 /* Quick and dirty way of stripping these symbols from the
505 symtab. */
506 if (bfd_is_abs_section (h->root.root.u.def.section))
507 h->root.written = TRUE;
510 return TRUE;
513 /* This is called to set the size of the .linux-dynamic section is.
514 It is called by the Linux linker emulation before_allocation
515 routine. We have finished reading all of the input files, and now
516 we just scan the hash tables to find out how many additional fixups
517 are required. */
519 bfd_boolean
520 bfd_m68klinux_size_dynamic_sections (bfd *output_bfd,
521 struct bfd_link_info *info)
523 struct fixup *f;
524 asection *s;
526 if (output_bfd->xvec != &MY(vec))
527 return TRUE;
529 /* First find the fixups... */
530 linux_link_hash_traverse (linux_hash_table (info),
531 linux_tally_symbols,
532 info);
534 /* If there are builtin fixups, leave room for a marker. This is
535 used by the dynamic linker so that it knows that all that follow
536 are builtin fixups instead of regular fixups. */
537 for (f = linux_hash_table (info)->fixup_list; f != NULL; f = f->next)
539 if (f->builtin)
541 ++linux_hash_table (info)->fixup_count;
542 ++linux_hash_table (info)->local_builtins;
543 break;
547 if (linux_hash_table (info)->dynobj == NULL)
549 if (linux_hash_table (info)->fixup_count > 0)
550 abort ();
551 return TRUE;
554 /* Allocate memory for our fixup table. We will fill it in later. */
555 s = bfd_get_section_by_name (linux_hash_table (info)->dynobj,
556 ".linux-dynamic");
557 if (s != NULL)
559 s->size = linux_hash_table (info)->fixup_count + 1;
560 s->size *= 8;
561 s->contents = (bfd_byte *) bfd_zalloc (output_bfd, s->size);
562 if (s->contents == NULL)
564 bfd_set_error (bfd_error_no_memory);
565 return FALSE;
569 return TRUE;
572 /* We come here once we are ready to actually write the fixup table to
573 the output file. Scan the fixup tables and so forth and generate
574 the stuff we need. */
576 static bfd_boolean
577 linux_finish_dynamic_link (bfd *output_bfd, struct bfd_link_info *info)
579 asection *s, *os, *is;
580 bfd_byte *fixup_table;
581 struct linux_link_hash_entry *h;
582 struct fixup *f;
583 unsigned int new_addr;
584 int section_offset;
585 unsigned int fixups_written;
587 if (linux_hash_table (info)->dynobj == NULL)
588 return TRUE;
590 s = bfd_get_section_by_name (linux_hash_table (info)->dynobj,
591 ".linux-dynamic");
592 BFD_ASSERT (s != NULL);
593 os = s->output_section;
594 fixups_written = 0;
596 #ifdef LINUX_LINK_DEBUG
597 printf ("Fixup table file offset: %x VMA: %x\n",
598 os->filepos + s->output_offset,
599 os->vma + s->output_offset);
600 #endif
602 fixup_table = s->contents;
603 bfd_put_32 (output_bfd, (bfd_vma) linux_hash_table (info)->fixup_count,
604 fixup_table);
605 fixup_table += 4;
607 /* Fill in fixup table. */
608 for (f = linux_hash_table (info)->fixup_list; f != NULL; f = f->next)
610 if (f->builtin)
611 continue;
613 if (f->h->root.root.type != bfd_link_hash_defined
614 && f->h->root.root.type != bfd_link_hash_defweak)
616 _bfd_error_handler
617 (_("Symbol %s not defined for fixups\n"),
618 f->h->root.root.root.string);
619 continue;
622 is = f->h->root.root.u.def.section;
623 section_offset = is->output_section->vma + is->output_offset;
624 new_addr = f->h->root.root.u.def.value + section_offset;
626 #ifdef LINUX_LINK_DEBUG
627 printf ("Fixup(%d) %s: %x %x\n",f->jump, f->h->root.root.string,
628 new_addr, f->value);
629 #endif
631 if (f->jump)
633 bfd_put_32 (output_bfd, (bfd_vma) new_addr, fixup_table);
634 fixup_table += 4;
635 bfd_put_32 (output_bfd, f->value + 2, fixup_table);
636 fixup_table += 4;
638 else
640 bfd_put_32 (output_bfd, (bfd_vma) new_addr, fixup_table);
641 fixup_table += 4;
642 bfd_put_32 (output_bfd, f->value, fixup_table);
643 fixup_table += 4;
645 ++fixups_written;
648 if (linux_hash_table (info)->local_builtins != 0)
650 /* Special marker so we know to switch to the other type of fixup */
651 bfd_put_32 (output_bfd, (bfd_vma) 0, fixup_table);
652 fixup_table += 4;
653 bfd_put_32 (output_bfd, (bfd_vma) 0, fixup_table);
654 fixup_table += 4;
655 ++fixups_written;
656 for (f = linux_hash_table (info)->fixup_list; f != NULL; f = f->next)
658 if (! f->builtin)
659 continue;
661 if (f->h->root.root.type != bfd_link_hash_defined
662 && f->h->root.root.type != bfd_link_hash_defweak)
664 _bfd_error_handler
665 (_("Symbol %s not defined for fixups\n"),
666 f->h->root.root.root.string);
667 continue;
670 is = f->h->root.root.u.def.section;
671 section_offset = is->output_section->vma + is->output_offset;
672 new_addr = f->h->root.root.u.def.value + section_offset;
674 #ifdef LINUX_LINK_DEBUG
675 printf ("Fixup(B) %s: %x %x\n", f->h->root.root.string,
676 new_addr, f->value);
677 #endif
679 bfd_put_32 (output_bfd, (bfd_vma) new_addr, fixup_table);
680 fixup_table += 4;
681 bfd_put_32 (output_bfd, f->value, fixup_table);
682 fixup_table += 4;
683 ++fixups_written;
687 if (linux_hash_table (info)->fixup_count != fixups_written)
689 _bfd_error_handler (_("Warning: fixup count mismatch\n"));
690 while (linux_hash_table (info)->fixup_count > fixups_written)
692 bfd_put_32 (output_bfd, (bfd_vma) 0, fixup_table);
693 fixup_table += 4;
694 bfd_put_32 (output_bfd, (bfd_vma) 0, fixup_table);
695 fixup_table += 4;
696 ++fixups_written;
700 h = linux_link_hash_lookup (linux_hash_table (info),
701 "__BUILTIN_FIXUPS__",
702 FALSE, FALSE, FALSE);
704 if (h != NULL
705 && (h->root.root.type == bfd_link_hash_defined
706 || h->root.root.type == bfd_link_hash_defweak))
708 is = h->root.root.u.def.section;
709 section_offset = is->output_section->vma + is->output_offset;
710 new_addr = h->root.root.u.def.value + section_offset;
712 #ifdef LINUX_LINK_DEBUG
713 printf ("Builtin fixup table at %x\n", new_addr);
714 #endif
716 bfd_put_32 (output_bfd, (bfd_vma) new_addr, fixup_table);
718 else
719 bfd_put_32 (output_bfd, (bfd_vma) 0, fixup_table);
721 if (bfd_seek (output_bfd, (file_ptr) (os->filepos + s->output_offset),
722 SEEK_SET) != 0)
723 return FALSE;
725 if (bfd_bwrite (s->contents, s->size, output_bfd) != s->size)
726 return FALSE;
728 return TRUE;
731 #define MY_bfd_link_hash_table_create linux_link_hash_table_create
732 #define MY_add_one_symbol linux_add_one_symbol
733 #define MY_finish_dynamic_link linux_finish_dynamic_link
735 #define MY_zmagic_contiguous 1
737 #include "aout-target.h"