1 /* BFD back-end for linux flavored m68k a.out binaries.
2 Copyright (C) 1992-2016 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)
31 #include "aout/aout64.h"
32 #include "aout/stab_gnu.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
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
51 static void MY_final_link_callback
52 (bfd *, file_ptr *, file_ptr *, file_ptr *);
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. */
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);
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_"
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_"
99 #define IS_PLT_SYM(name) (CONST_STRNEQ (name, PLT_REF_PREFIX))
101 /* This string is used to generate specialized error messages. */
104 #define NEEDS_SHRLIB "__NEEDS_SHRLIB_"
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
114 #ifndef SHARABLE_CONFLICTS
115 #define SHARABLE_CONFLICTS "__SHARABLE_CONFLICTS__"
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. */
131 struct linux_link_hash_entry *h;
134 /* Nonzero if this is a jump instruction that needs to be fixed,
135 zero if this is just a pointer */
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
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. */
157 /* Number of fixups. */
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,
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
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)));
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,
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)))
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),\
228 /* Traverse a Linux link hash table. */
230 #define linux_link_hash_traverse(table, func, info) \
231 (aout_link_hash_traverse \
233 (bfd_boolean (*) (struct aout_link_hash_entry *, void *)) (func), \
236 /* Get the Linux link hash table from the info structure. This is
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,
251 f = (struct fixup *) bfd_hash_allocate (&info->hash->table,
252 sizeof (struct fixup));
255 f->next = linux_hash_table (info)->fixup_list;
256 linux_hash_table (info)->fixup_list = f;
259 f->builtin = builtin;
261 ++linux_hash_table (info)->fixup_count;
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. */
273 linux_link_create_dynamic_sections (bfd *abfd,
274 struct bfd_link_info *info ATTRIBUTE_UNUSED)
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.
284 s = bfd_make_section_with_flags (abfd, ".linux-dynamic", flags);
286 || ! bfd_set_section_alignment (abfd, s, 2))
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. */
299 linux_add_one_symbol (struct bfd_link_info *info,
308 struct bfd_link_hash_entry **hashp)
310 struct linux_link_hash_entry *h;
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. */
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))
331 linux_hash_table (info)->dynobj = abfd;
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,
341 && (h->root.root.type == bfd_link_hash_defined
342 || h->root.root.type == bfd_link_hash_defweak))
347 *hashp = (struct bfd_link_hash_entry *) h;
349 f = new_fixup (info, h, value, ! IS_PLT_SYM (name));
352 f->jump = IS_PLT_SYM (name);
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,
364 /* Insert a pointer to our table in the set vector. The dynamic
365 linker requires this information */
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,
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)))
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. */
397 linux_tally_symbols (struct linux_link_hash_entry *h,
400 struct bfd_link_info *info = (struct bfd_link_info *) data;
401 struct fixup *f, *f1;
403 struct linux_link_hash_entry *h1, *h2;
406 if (h->root.root.type == bfd_link_hash_undefined
407 && CONST_STRNEQ (h->root.root.root.string, NEEDS_SHRLIB))
413 name = h->root.root.root.string + sizeof NEEDS_SHRLIB - 1;
414 p = strrchr (name, '_');
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"),
423 strcpy (alloc, name);
424 p = strrchr (alloc, '_');
426 (*_bfd_error_handler)
427 (_("Output file requires shared library `%s.so.%s'\n"),
435 /* If this symbol is not a PLT/GOT, we do not even need to look at it */
436 is_plt = IS_PLT_SYM (h->root.root.root.string);
438 if (is_plt || IS_GOT_SYM (h->root.root.root.string))
440 /* Look up this symbol twice. Once just as a regular lookup,
441 and then again following all of the indirect links until we
442 reach a real symbol. */
443 h1 = linux_link_hash_lookup (linux_hash_table (info),
444 (h->root.root.root.string
445 + sizeof PLT_REF_PREFIX - 1),
447 /* h2 does not follow indirect symbols. */
448 h2 = linux_link_hash_lookup (linux_hash_table (info),
449 (h->root.root.root.string
450 + sizeof PLT_REF_PREFIX - 1),
451 FALSE, FALSE, FALSE);
453 /* The real symbol must exist but if it is also an ABS symbol,
454 there is no need to have a fixup. This is because they both
455 came from the same library. If on the other hand, we had to
456 use an indirect symbol to get to the real symbol, we add the
457 fixup anyway, since there are cases where these symbols come
458 from different shared libraries */
460 && (((h1->root.root.type == bfd_link_hash_defined
461 || h1->root.root.type == bfd_link_hash_defweak)
462 && ! bfd_is_abs_section (h1->root.root.u.def.section))
463 || h2->root.root.type == bfd_link_hash_indirect))
465 /* See if there is a "builtin" fixup already present
466 involving this symbol. If so, convert it to a regular
467 fixup. In the end, this relaxes some of the requirements
468 about the order of performing fixups. */
470 for (f1 = linux_hash_table (info)->fixup_list;
474 if ((f1->h != h && f1->h != h1)
475 || (! f1->builtin && ! f1->jump))
480 && bfd_is_abs_section (h->root.root.u.def.section))
482 f = new_fixup (info, h1, f1->h->root.root.u.def.value, 0);
491 && bfd_is_abs_section (h->root.root.u.def.section))
493 f = new_fixup (info, h1, h->root.root.u.def.value, 0);
496 /* FIXME: No way to return error. */
503 /* Quick and dirty way of stripping these symbols from the
505 if (bfd_is_abs_section (h->root.root.u.def.section))
506 h->root.written = TRUE;
512 /* This is called to set the size of the .linux-dynamic section is.
513 It is called by the Linux linker emulation before_allocation
514 routine. We have finished reading all of the input files, and now
515 we just scan the hash tables to find out how many additional fixups
519 bfd_m68klinux_size_dynamic_sections (bfd *output_bfd,
520 struct bfd_link_info *info)
525 if (output_bfd->xvec != &MY(vec))
528 /* First find the fixups... */
529 linux_link_hash_traverse (linux_hash_table (info),
533 /* If there are builtin fixups, leave room for a marker. This is
534 used by the dynamic linker so that it knows that all that follow
535 are builtin fixups instead of regular fixups. */
536 for (f = linux_hash_table (info)->fixup_list; f != NULL; f = f->next)
540 ++linux_hash_table (info)->fixup_count;
541 ++linux_hash_table (info)->local_builtins;
546 if (linux_hash_table (info)->dynobj == NULL)
548 if (linux_hash_table (info)->fixup_count > 0)
553 /* Allocate memory for our fixup table. We will fill it in later. */
554 s = bfd_get_section_by_name (linux_hash_table (info)->dynobj,
558 s->size = linux_hash_table (info)->fixup_count + 1;
560 s->contents = (bfd_byte *) bfd_zalloc (output_bfd, s->size);
561 if (s->contents == NULL)
563 bfd_set_error (bfd_error_no_memory);
571 /* We come here once we are ready to actually write the fixup table to
572 the output file. Scan the fixup tables and so forth and generate
573 the stuff we need. */
576 linux_finish_dynamic_link (bfd *output_bfd, struct bfd_link_info *info)
578 asection *s, *os, *is;
579 bfd_byte *fixup_table;
580 struct linux_link_hash_entry *h;
582 unsigned int new_addr;
584 unsigned int fixups_written;
586 if (linux_hash_table (info)->dynobj == NULL)
589 s = bfd_get_section_by_name (linux_hash_table (info)->dynobj,
591 BFD_ASSERT (s != NULL);
592 os = s->output_section;
595 #ifdef LINUX_LINK_DEBUG
596 printf ("Fixup table file offset: %x VMA: %x\n",
597 os->filepos + s->output_offset,
598 os->vma + s->output_offset);
601 fixup_table = s->contents;
602 bfd_put_32 (output_bfd, (bfd_vma) linux_hash_table (info)->fixup_count,
606 /* Fill in fixup table. */
607 for (f = linux_hash_table (info)->fixup_list; f != NULL; f = f->next)
612 if (f->h->root.root.type != bfd_link_hash_defined
613 && f->h->root.root.type != bfd_link_hash_defweak)
615 (*_bfd_error_handler)
616 (_("Symbol %s not defined for fixups\n"),
617 f->h->root.root.root.string);
621 is = f->h->root.root.u.def.section;
622 section_offset = is->output_section->vma + is->output_offset;
623 new_addr = f->h->root.root.u.def.value + section_offset;
625 #ifdef LINUX_LINK_DEBUG
626 printf ("Fixup(%d) %s: %x %x\n",f->jump, f->h->root.root.string,
632 bfd_put_32 (output_bfd, (bfd_vma) new_addr, fixup_table);
634 bfd_put_32 (output_bfd, f->value + 2, fixup_table);
639 bfd_put_32 (output_bfd, (bfd_vma) new_addr, fixup_table);
641 bfd_put_32 (output_bfd, f->value, fixup_table);
647 if (linux_hash_table (info)->local_builtins != 0)
649 /* Special marker so we know to switch to the other type of fixup */
650 bfd_put_32 (output_bfd, (bfd_vma) 0, fixup_table);
652 bfd_put_32 (output_bfd, (bfd_vma) 0, fixup_table);
655 for (f = linux_hash_table (info)->fixup_list; f != NULL; f = f->next)
660 if (f->h->root.root.type != bfd_link_hash_defined
661 && f->h->root.root.type != bfd_link_hash_defweak)
663 (*_bfd_error_handler)
664 (_("Symbol %s not defined for fixups\n"),
665 f->h->root.root.root.string);
669 is = f->h->root.root.u.def.section;
670 section_offset = is->output_section->vma + is->output_offset;
671 new_addr = f->h->root.root.u.def.value + section_offset;
673 #ifdef LINUX_LINK_DEBUG
674 printf ("Fixup(B) %s: %x %x\n", f->h->root.root.string,
678 bfd_put_32 (output_bfd, (bfd_vma) new_addr, fixup_table);
680 bfd_put_32 (output_bfd, f->value, fixup_table);
686 if (linux_hash_table (info)->fixup_count != fixups_written)
688 (*_bfd_error_handler) (_("Warning: fixup count mismatch\n"));
689 while (linux_hash_table (info)->fixup_count > fixups_written)
691 bfd_put_32 (output_bfd, (bfd_vma) 0, fixup_table);
693 bfd_put_32 (output_bfd, (bfd_vma) 0, fixup_table);
699 h = linux_link_hash_lookup (linux_hash_table (info),
700 "__BUILTIN_FIXUPS__",
701 FALSE, FALSE, FALSE);
704 && (h->root.root.type == bfd_link_hash_defined
705 || h->root.root.type == bfd_link_hash_defweak))
707 is = h->root.root.u.def.section;
708 section_offset = is->output_section->vma + is->output_offset;
709 new_addr = h->root.root.u.def.value + section_offset;
711 #ifdef LINUX_LINK_DEBUG
712 printf ("Builtin fixup table at %x\n", new_addr);
715 bfd_put_32 (output_bfd, (bfd_vma) new_addr, fixup_table);
718 bfd_put_32 (output_bfd, (bfd_vma) 0, fixup_table);
720 if (bfd_seek (output_bfd, (file_ptr) (os->filepos + s->output_offset),
724 if (bfd_bwrite (s->contents, s->size, output_bfd) != s->size)
730 #define MY_bfd_link_hash_table_create linux_link_hash_table_create
731 #define MY_add_one_symbol linux_add_one_symbol
732 #define MY_finish_dynamic_link linux_finish_dynamic_link
734 #define MY_zmagic_contiguous 1
736 #include "aout-target.h"