1/* VxWorks support for ELF
2   Copyright 2005, 2007 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 "sysdep.h"
24#include "bfd.h"
25#include "libbfd.h"
26#include "elf-bfd.h"
27#include "elf-vxworks.h"
28
29/* Return true if symbol NAME, as defined by ABFD, is one of the special
30   __GOTT_BASE__ or __GOTT_INDEX__ symbols.  */
31
32static bfd_boolean
33elf_vxworks_gott_symbol_p (bfd *abfd, const char *name)
34{
35  char leading;
36
37  leading = bfd_get_symbol_leading_char (abfd);
38  if (leading)
39    {
40      if (*name != leading)
41	return FALSE;
42      name++;
43    }
44  return (strcmp (name, "__GOTT_BASE__") == 0
45	  || strcmp (name, "__GOTT_INDEX__") == 0);
46}
47
48/* Tweak magic VxWorks symbols as they are loaded.  */
49bfd_boolean
50elf_vxworks_add_symbol_hook (bfd *abfd,
51			     struct bfd_link_info *info,
52			     Elf_Internal_Sym *sym,
53			     const char **namep,
54			     flagword *flagsp,
55			     asection **secp ATTRIBUTE_UNUSED,
56			     bfd_vma *valp ATTRIBUTE_UNUSED)
57{
58  /* Ideally these "magic" symbols would be exported by libc.so.1
59     which would be found via a DT_NEEDED tag, and then handled
60     specially by the linker at runtime.  Except shared libraries
61     don't even link to libc.so.1 by default...
62     If the symbol is imported from, or will be put in a shared library,
63     give the symbol weak binding to get the desired samantics.
64     This transformation will be undone in
65     elf_i386_vxworks_link_output_symbol_hook. */
66  if ((info->shared || abfd->flags & DYNAMIC)
67      && elf_vxworks_gott_symbol_p (abfd, *namep))
68    {
69      sym->st_info = ELF_ST_INFO (STB_WEAK, ELF_ST_TYPE (sym->st_info));
70      *flagsp |= BSF_WEAK;
71    }
72
73  return TRUE;
74}
75
76/* Perform VxWorks-specific handling of the create_dynamic_sections hook.
77   When creating an executable, set *SRELPLT2_OUT to the .rel(a).plt.unloaded
78   section.  */
79
80bfd_boolean
81elf_vxworks_create_dynamic_sections (bfd *dynobj, struct bfd_link_info *info,
82				     asection **srelplt2_out)
83{
84  struct elf_link_hash_table *htab;
85  const struct elf_backend_data *bed;
86  asection *s;
87
88  htab = elf_hash_table (info);
89  bed = get_elf_backend_data (dynobj);
90
91  if (!info->shared)
92    {
93      s = bfd_make_section_with_flags (dynobj,
94				       bed->default_use_rela_p
95				       ? ".rela.plt.unloaded"
96				       : ".rel.plt.unloaded",
97				       SEC_HAS_CONTENTS | SEC_IN_MEMORY
98				       | SEC_READONLY | SEC_LINKER_CREATED);
99      if (s == NULL
100	  || !bfd_set_section_alignment (dynobj, s, bed->s->log_file_align))
101	return FALSE;
102
103      *srelplt2_out = s;
104    }
105
106  /* Mark the GOT and PLT symbols as having relocations; they might
107     not, but we won't know for sure until we build the GOT in
108     finish_dynamic_symbol.  Also make sure that the GOT symbol
109     is entered into the dynamic symbol table; the loader uses it
110     to initialize __GOTT_BASE__[__GOTT_INDEX__].  */
111  if (htab->hgot)
112    {
113      htab->hgot->indx = -2;
114      htab->hgot->other &= ~ELF_ST_VISIBILITY (-1);
115      htab->hgot->forced_local = 0;
116      if (!bfd_elf_link_record_dynamic_symbol (info, htab->hgot))
117	return FALSE;
118    }
119  if (htab->hplt)
120    {
121      htab->hplt->indx = -2;
122      htab->hplt->type = STT_FUNC;
123    }
124
125  return TRUE;
126}
127
128/* Tweak magic VxWorks symbols as they are written to the output file.  */
129bfd_boolean
130elf_vxworks_link_output_symbol_hook (struct bfd_link_info *info
131				       ATTRIBUTE_UNUSED,
132				     const char *name,
133				     Elf_Internal_Sym *sym,
134				     asection *input_sec ATTRIBUTE_UNUSED,
135				     struct elf_link_hash_entry *h)
136{
137  /* Reverse the effects of the hack in elf_vxworks_add_symbol_hook.  */
138  if (h
139      && h->root.type == bfd_link_hash_undefweak
140      && elf_vxworks_gott_symbol_p (h->root.u.undef.abfd, name))
141    sym->st_info = ELF_ST_INFO (STB_GLOBAL, ELF_ST_TYPE (sym->st_info));
142
143  return TRUE;
144}
145
146
147/* Copy relocations into the output file.  Fixes up relocations againt PLT
148   entries, then calls the generic routine.  */
149
150bfd_boolean
151elf_vxworks_emit_relocs (bfd *output_bfd,
152			 asection *input_section,
153			 Elf_Internal_Shdr *input_rel_hdr,
154			 Elf_Internal_Rela *internal_relocs,
155			 struct elf_link_hash_entry **rel_hash)
156{
157  const struct elf_backend_data *bed;
158  Elf_Internal_Rela *irela;
159  Elf_Internal_Rela *irelaend;
160  int j;
161
162  bed = get_elf_backend_data (output_bfd);
163
164  irela = internal_relocs;
165  irelaend = irela + (NUM_SHDR_ENTRIES (input_rel_hdr)
166		      * bed->s->int_rels_per_ext_rel);
167  while (irela < irelaend)
168    {
169      if ((output_bfd->flags & (DYNAMIC|EXEC_P))
170	  && *rel_hash
171	  && (*rel_hash)->def_dynamic
172	  && !(*rel_hash)->def_regular
173	  && ((*rel_hash)->root.type == bfd_link_hash_defined
174	      || (*rel_hash)->root.type == bfd_link_hash_defweak)
175	  && (*rel_hash)->root.u.def.section->output_section != NULL)
176	{
177	  /* This is a relocation from an executable or shared library
178	     against a symbol in a different shared library.  We are
179	     creating a definition in the output file but it does not come
180	     from any of our normal (.o) files. ie. a PLT stub.
181	     Normally this would be a relocation against against SHN_UNDEF
182	     with the VMA of the PLT stub.  This upsets the VxWorks loader.
183	     Convert it to a section-relative relocation.
184	     This gets some other symbols (for instance .dynbss),
185	     but is conservatively correct.  */
186	  for (j = 0; j < bed->s->int_rels_per_ext_rel; j++)
187	    {
188	      asection *sec = (*rel_hash)->root.u.def.section;
189	      int this_idx = sec->output_section->target_index;
190
191	      irela[j].r_info = ELF32_R_INFO (this_idx,
192		  ELF32_R_TYPE (irela[j].r_info));
193	      irela[j].r_addend += (*rel_hash)->root.u.def.value;
194	      irela[j].r_addend += sec->output_offset;
195	    }
196	  /* Stop the generic routine adjusting this entry.  */
197	  *rel_hash = NULL;
198	}
199      irela += bed->s->int_rels_per_ext_rel;
200      rel_hash++;
201    }
202  return _bfd_elf_link_output_relocs (output_bfd, input_section,
203				      input_rel_hdr, internal_relocs,
204				      rel_hash);
205}
206
207
208/* Set the sh_link and sh_info fields on the static plt relocation secton.  */
209
210void
211elf_vxworks_final_write_processing (bfd *abfd,
212				    bfd_boolean linker ATTRIBUTE_UNUSED)
213{
214  asection * sec;
215  struct bfd_elf_section_data *d;
216
217  sec = bfd_get_section_by_name (abfd, ".rel.plt.unloaded");
218  if (!sec)
219    sec = bfd_get_section_by_name (abfd, ".rela.plt.unloaded");
220  if (!sec)
221    return;
222  d = elf_section_data (sec);
223  d->this_hdr.sh_link = elf_tdata (abfd)->symtab_section;
224  sec = bfd_get_section_by_name (abfd, ".plt");
225  if (sec)
226    d->this_hdr.sh_info = elf_section_data (sec)->this_idx;
227}
228