1/* VxWorks support for ELF
2   Copyright 2005 Free Software Foundation, Inc.
3
4   This file is part of BFD, the Binary File Descriptor library.
5
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 2 of the License, or
9   (at your option) any later version.
10
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.
15
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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
19 */
20
21/* This file provides routines used by all VxWorks targets.  */
22
23#include "bfd.h"
24#include "sysdep.h"
25#include "libbfd.h"
26#include "elf-bfd.h"
27#include "elf-vxworks.h"
28
29/* Tweak magic VxWorks symbols as they are loaded.  */
30bfd_boolean
31elf_vxworks_add_symbol_hook (bfd *abfd ATTRIBUTE_UNUSED,
32			     struct bfd_link_info *info,
33			     Elf_Internal_Sym *sym,
34			     const char **namep,
35			     flagword *flagsp,
36			     asection **secp ATTRIBUTE_UNUSED,
37			     bfd_vma *valp ATTRIBUTE_UNUSED)
38{
39  /* Ideally these "magic" symbols would be exported by libc.so.1
40     which would be found via a DT_NEEDED tag, and then handled
41     specially by the linker at runtime.  Except shared libraries
42     don't even link to libc.so.1 by default...
43     If the symbol is imported from, or will be put in a shared library,
44     give the symbol weak binding to get the desired samantics.
45     This transformation will be undone in
46     elf_i386_vxworks_link_output_symbol_hook. */
47  if ((info->shared || abfd->flags & DYNAMIC)
48      && (strcmp (*namep, "__GOTT_INDEX__") == 0
49	  || strcmp (*namep, "__GOTT_BASE__") == 0))
50    {
51      sym->st_info = ELF_ST_INFO (STB_WEAK, ELF_ST_TYPE (sym->st_info));
52      *flagsp |= BSF_WEAK;
53    }
54
55  return TRUE;
56}
57
58/* Perform VxWorks-specific handling of the create_dynamic_sections hook.
59   When creating an executable, set *SRELPLT2_OUT to the .rel(a).plt.unloaded
60   section.  */
61
62bfd_boolean
63elf_vxworks_create_dynamic_sections (bfd *dynobj, struct bfd_link_info *info,
64				     asection **srelplt2_out)
65{
66  struct elf_link_hash_table *htab;
67  const struct elf_backend_data *bed;
68  asection *s;
69
70  htab = elf_hash_table (info);
71  bed = get_elf_backend_data (dynobj);
72
73  if (!info->shared)
74    {
75      s = bfd_make_section_with_flags (dynobj,
76				       bed->default_use_rela_p
77				       ? ".rela.plt.unloaded"
78				       : ".rel.plt.unloaded",
79				       SEC_HAS_CONTENTS | SEC_IN_MEMORY
80				       | SEC_READONLY | SEC_LINKER_CREATED);
81      if (s == NULL
82	  || !bfd_set_section_alignment (dynobj, s, bed->s->log_file_align))
83	return FALSE;
84
85      *srelplt2_out = s;
86    }
87
88  /* Mark the GOT and PLT symbols as having relocations; they might
89     not, but we won't know for sure until we build the GOT in
90     finish_dynamic_symbol.  Also make sure that the GOT symbol
91     is entered into the dynamic symbol table; the loader uses it
92     to initialize __GOTT_BASE__[__GOTT_INDEX__].  */
93  if (htab->hgot)
94    {
95      htab->hgot->indx = -2;
96      htab->hgot->other &= ~ELF_ST_VISIBILITY (-1);
97      htab->hgot->forced_local = 0;
98      if (!bfd_elf_link_record_dynamic_symbol (info, htab->hgot))
99	return FALSE;
100    }
101  if (htab->hplt)
102    {
103      htab->hplt->indx = -2;
104      htab->hplt->type = STT_FUNC;
105    }
106
107  return TRUE;
108}
109
110/* Tweak magic VxWorks symbols as they are written to the output file.  */
111bfd_boolean
112elf_vxworks_link_output_symbol_hook (struct bfd_link_info *info
113				       ATTRIBUTE_UNUSED,
114				     const char *name,
115				     Elf_Internal_Sym *sym,
116				     asection *input_sec ATTRIBUTE_UNUSED,
117				     struct elf_link_hash_entry *h
118				       ATTRIBUTE_UNUSED)
119{
120  /* Ignore the first dummy symbol.  */
121  if (!name)
122    return TRUE;
123
124  /* Reverse the effects of the hack in elf_vxworks_add_symbol_hook.  */
125  if (strcmp (name, "__GOTT_INDEX__") == 0
126      || strcmp (name, "__GOTT_BASE__") == 0)
127    sym->st_info = ELF_ST_INFO (STB_GLOBAL, ELF_ST_TYPE (sym->st_info));
128
129  return TRUE;
130}
131
132
133/* Copy relocations into the output file.  Fixes up relocations againt PLT
134   entries, then calls the generic routine.  */
135
136bfd_boolean
137elf_vxworks_emit_relocs (bfd *output_bfd,
138			 asection *input_section,
139			 Elf_Internal_Shdr *input_rel_hdr,
140			 Elf_Internal_Rela *internal_relocs,
141			 struct elf_link_hash_entry **rel_hash)
142{
143  const struct elf_backend_data *bed;
144  Elf_Internal_Rela *irela;
145  Elf_Internal_Rela *irelaend;
146  int j;
147
148  bed = get_elf_backend_data (output_bfd);
149
150  irela = internal_relocs;
151  irelaend = irela + (NUM_SHDR_ENTRIES (input_rel_hdr)
152		      * bed->s->int_rels_per_ext_rel);
153  while (irela < irelaend)
154    {
155      if ((output_bfd->flags & (DYNAMIC|EXEC_P))
156	  && *rel_hash
157	  && (*rel_hash)->def_dynamic
158	  && !(*rel_hash)->def_regular
159	  && (*rel_hash)->root.type == bfd_link_hash_defined
160	  && (*rel_hash)->root.u.def.section->output_section != NULL)
161	{
162	  /* This is a relocation from an executable or shared library
163	     against a symbol in a different shared library.  We are
164	     creating a definition in the output file but it does not come
165	     from any of our normal (.o) files. ie. a PLT stub.
166	     Normally this would be a relocation against against SHN_UNDEF
167	     with the VMA of the PLT stub.  This upsets the VxWorks loader.
168	     Convert it to a section-relative relocation.
169	     This gets some other symbols (for instance .dynbss),
170	     but is conservatively correct.  */
171	  for (j = 0; j < bed->s->int_rels_per_ext_rel; j++)
172	    {
173	      asection *sec = (*rel_hash)->root.u.def.section;
174	      int this_idx =
175		elf_section_data (sec->output_section)->this_idx;
176
177	      irela[j].r_info = ELF32_R_INFO (this_idx,
178		  ELF32_R_TYPE (irela[j].r_info));
179	      irela[j].r_addend += (*rel_hash)->root.u.def.value;
180	      irela[j].r_addend += sec->output_offset;
181	    }
182	  /* Stop the generic routine adjusting this entry.  */
183	  *rel_hash = NULL;
184	}
185      irela += bed->s->int_rels_per_ext_rel;
186      rel_hash++;
187    }
188  return _bfd_elf_link_output_relocs (output_bfd, input_section,
189				      input_rel_hdr, internal_relocs,
190				      rel_hash);
191}
192
193
194/* Set the sh_link and sh_info fields on the static plt relocation secton.  */
195
196void
197elf_vxworks_final_write_processing (bfd *abfd,
198				    bfd_boolean linker ATTRIBUTE_UNUSED)
199{
200  asection * sec;
201  struct bfd_elf_section_data *d;
202
203  sec = bfd_get_section_by_name (abfd, ".rel.plt.unloaded");
204  if (!sec)
205    sec = bfd_get_section_by_name (abfd, ".rela.plt.unloaded");
206  if (!sec)
207    return;
208  d = elf_section_data (sec);
209  d->this_hdr.sh_link = elf_tdata (abfd)->symtab_section;
210  sec = bfd_get_section_by_name (abfd, ".plt");
211  if (sec)
212    d->this_hdr.sh_info = elf_section_data (sec)->this_idx;
213}
214