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. */
30 bfd_boolean
elf_vxworks_add_symbol_hook(bfd * abfd ATTRIBUTE_UNUSED,struct bfd_link_info * info,Elf_Internal_Sym * sym,const char ** namep,flagword * flagsp,asection ** secp ATTRIBUTE_UNUSED,bfd_vma * valp ATTRIBUTE_UNUSED)31 elf_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
62 bfd_boolean
elf_vxworks_create_dynamic_sections(bfd * dynobj,struct bfd_link_info * info,asection ** srelplt2_out)63 elf_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. */
111 bfd_boolean
elf_vxworks_link_output_symbol_hook(struct bfd_link_info * info ATTRIBUTE_UNUSED,const char * name,Elf_Internal_Sym * sym,asection * input_sec ATTRIBUTE_UNUSED,struct elf_link_hash_entry * h ATTRIBUTE_UNUSED)112 elf_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
136 bfd_boolean
elf_vxworks_emit_relocs(bfd * output_bfd,asection * input_section,Elf_Internal_Shdr * input_rel_hdr,Elf_Internal_Rela * internal_relocs,struct elf_link_hash_entry ** rel_hash)137 elf_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
196 void
elf_vxworks_final_write_processing(bfd * abfd,bfd_boolean linker ATTRIBUTE_UNUSED)197 elf_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