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470b557a AK |
1 | /* IBM S/390-specific support for ELF 32 and 64 bit functions |
2 | Copyright 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, | |
3 | 2011, 2012 Free Software Foundation, Inc. | |
4 | Contributed by Andreas Krebbel. | |
5 | ||
6 | This file is part of BFD, the Binary File Descriptor library. | |
7 | ||
8 | This program is free software; you can redistribute it and/or modify | |
9 | it under the terms of the GNU General Public License as published by | |
10 | the Free Software Foundation; either version 3 of the License, or | |
11 | (at your option) any later version. | |
12 | ||
13 | This program is distributed in the hope that it will be useful, | |
14 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
16 | GNU General Public License for more details. | |
17 | ||
18 | You should have received a copy of the GNU General Public License | |
19 | along with this program; if not, write to the Free Software | |
20 | Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA | |
21 | 02110-1301, USA. */ | |
22 | ||
23 | ||
24 | /* Return TRUE if H is an IFUNC symbol. Simply checking for the | |
25 | symbol type might not be enough since it might get changed to | |
26 | STT_FUNC for pointer equality reasons. */ | |
27 | static inline bfd_boolean | |
28 | s390_is_ifunc_symbol_p (struct elf_link_hash_entry *h) | |
29 | { | |
30 | struct elf_s390_link_hash_entry *eh = (struct elf_s390_link_hash_entry*)h; | |
31 | return h->type == STT_GNU_IFUNC || eh->ifunc_resolver_address != 0; | |
32 | } | |
33 | ||
34 | /* Create sections needed by STT_GNU_IFUNC symbol. */ | |
35 | ||
36 | static bfd_boolean | |
37 | s390_elf_create_ifunc_sections (bfd *abfd, struct bfd_link_info *info) | |
38 | { | |
39 | flagword flags; | |
40 | asection *s; | |
41 | const struct elf_backend_data *bed = get_elf_backend_data (abfd); | |
42 | struct elf_link_hash_table *htab = elf_hash_table (info); | |
43 | ||
44 | if (htab->iplt != NULL) | |
45 | return TRUE; | |
46 | ||
47 | flags = bed->dynamic_sec_flags; | |
48 | ||
49 | if (info->shared) | |
50 | { | |
51 | s = bfd_make_section_with_flags (abfd, ".rela.ifunc", | |
52 | flags | SEC_READONLY); | |
53 | if (s == NULL | |
54 | || ! bfd_set_section_alignment (abfd, s, | |
55 | bed->s->log_file_align)) | |
56 | return FALSE; | |
57 | htab->irelifunc = s; | |
58 | } | |
59 | ||
60 | /* Create .iplt, .rel[a].iplt, and .igot.plt. */ | |
61 | s = bfd_make_section_with_flags (abfd, ".iplt", | |
62 | flags | SEC_CODE | SEC_READONLY); | |
63 | if (s == NULL | |
64 | || ! bfd_set_section_alignment (abfd, s, bed->plt_alignment)) | |
65 | return FALSE; | |
66 | htab->iplt = s; | |
67 | ||
68 | s = bfd_make_section_with_flags (abfd, ".rela.iplt", flags | SEC_READONLY); | |
69 | if (s == NULL | |
70 | || ! bfd_set_section_alignment (abfd, s, | |
71 | bed->s->log_file_align)) | |
72 | return FALSE; | |
73 | htab->irelplt = s; | |
74 | ||
75 | s = bfd_make_section_with_flags (abfd, ".igot.plt", flags); | |
76 | if (s == NULL | |
77 | || !bfd_set_section_alignment (abfd, s, | |
78 | bed->s->log_file_align)) | |
79 | return FALSE; | |
80 | htab->igotplt = s; | |
81 | ||
82 | return TRUE; | |
83 | } | |
84 | ||
85 | ||
86 | /* Allocate space in .plt, .got and associated reloc sections for | |
87 | dynamic relocs against a STT_GNU_IFUNC symbol definition. */ | |
88 | ||
89 | static bfd_boolean | |
90 | s390_elf_allocate_ifunc_dyn_relocs (struct bfd_link_info *info, | |
91 | struct elf_link_hash_entry *h, | |
92 | struct elf_dyn_relocs **head) | |
93 | { | |
94 | struct elf_dyn_relocs *p; | |
95 | struct elf_link_hash_table *htab; | |
96 | struct elf_s390_link_hash_entry *eh = (struct elf_s390_link_hash_entry*)h; | |
97 | ||
98 | htab = elf_hash_table (info); | |
99 | eh->ifunc_resolver_address = h->root.u.def.value; | |
100 | eh->ifunc_resolver_section = h->root.u.def.section; | |
101 | ||
102 | /* Support garbage collection against STT_GNU_IFUNC symbols. */ | |
103 | if (h->plt.refcount <= 0 && h->got.refcount <= 0) | |
104 | { | |
105 | /* When building shared library, we need to handle the case | |
106 | where it is marked with regular reference, but not non-GOT | |
107 | reference. It may happen if we didn't see STT_GNU_IFUNC | |
108 | symbol at the time when checking relocations. */ | |
109 | if (info->shared | |
110 | && !h->non_got_ref | |
111 | && h->ref_regular) | |
112 | for (p = *head; p != NULL; p = p->next) | |
113 | if (p->count) | |
114 | { | |
115 | h->non_got_ref = 1; | |
116 | goto keep; | |
117 | } | |
118 | ||
119 | h->got = htab->init_got_offset; | |
120 | h->plt = htab->init_plt_offset; | |
121 | *head = NULL; | |
122 | return TRUE; | |
123 | } | |
124 | ||
125 | /* Return and discard space for dynamic relocations against it if | |
126 | it is never referenced in a non-shared object. */ | |
127 | if (!h->ref_regular) | |
128 | { | |
129 | if (h->plt.refcount > 0 | |
130 | || h->got.refcount > 0) | |
131 | abort (); | |
132 | h->got = htab->init_got_offset; | |
133 | h->plt = htab->init_plt_offset; | |
134 | *head = NULL; | |
135 | return TRUE; | |
136 | } | |
137 | ||
138 | keep: | |
139 | /* Without checking h->plt.refcount here we allocate a PLT slot. | |
140 | When setting plt.refcount in check_relocs it might not have been | |
141 | known that this will be an IFUNC symol. */ | |
142 | h->plt.offset = htab->iplt->size; | |
143 | h->needs_plt = 1; | |
144 | htab->iplt->size += PLT_ENTRY_SIZE; | |
145 | htab->igotplt->size += GOT_ENTRY_SIZE; | |
146 | htab->irelplt->size += RELA_ENTRY_SIZE; | |
147 | htab->irelplt->reloc_count++; | |
148 | ||
149 | /* In order to make pointer equality work with IFUNC symbols defined | |
150 | in a non-PIE executable and referenced in a shared lib, we turn | |
151 | the symbol into a STT_FUNC symbol and make the symbol value to | |
152 | point to the IPLT slot. That way the referencing shared lib will | |
153 | always get the PLT slot address when resolving the respective | |
154 | R_390_GLOB_DAT/R_390_64 relocs on that symbol. */ | |
155 | if (info->executable && !info->shared && h->def_regular && h->ref_dynamic) | |
156 | { | |
157 | h->root.u.def.section = htab->iplt; | |
158 | h->root.u.def.value = h->plt.offset; | |
159 | h->size = PLT_ENTRY_SIZE; | |
160 | h->type = STT_FUNC; | |
161 | } | |
162 | ||
163 | /* We need dynamic relocation for STT_GNU_IFUNC symbol only when | |
164 | there is a non-GOT reference in a shared object. */ | |
165 | if (!info->shared || !h->non_got_ref) | |
166 | *head = NULL; | |
167 | ||
168 | /* Finally, allocate space. */ | |
169 | p = *head; | |
170 | if (p != NULL) | |
171 | { | |
172 | bfd_size_type count = 0; | |
173 | do | |
174 | { | |
175 | count += p->count; | |
176 | p = p->next; | |
177 | } | |
178 | while (p != NULL); | |
179 | htab->irelifunc->size += count * RELA_ENTRY_SIZE; | |
180 | } | |
181 | ||
182 | /* Decide whether the got.iplt slot can be used. This has to be | |
183 | avoided if the values in the GOT slots could differ for pointer | |
184 | equality reasons. */ | |
185 | if (h->got.refcount <= 0 | |
186 | || (info->shared | |
187 | && (h->dynindx == -1 || h->forced_local)) | |
188 | || (info->executable && info->shared) | |
189 | || htab->sgot == NULL) | |
190 | { | |
191 | /* Use .got.iplt. */ | |
192 | h->got.offset = (bfd_vma) -1; | |
193 | } | |
194 | else | |
195 | { | |
196 | h->got.offset = htab->sgot->size; | |
197 | htab->sgot->size += GOT_ENTRY_SIZE; | |
198 | if (info->shared) | |
199 | htab->srelgot->size += RELA_ENTRY_SIZE; | |
200 | } | |
201 | ||
202 | return TRUE; | |
203 | } | |
204 | ||
205 | static bfd_boolean | |
206 | elf_s390_allocate_local_syminfo (bfd *abfd, Elf_Internal_Shdr *symtab_hdr) | |
207 | { | |
208 | bfd_size_type size; | |
209 | ||
210 | size = symtab_hdr->sh_info; | |
211 | size *= (sizeof (bfd_signed_vma) /* local got */ | |
212 | + sizeof (struct plt_entry) /* local plt */ | |
213 | + sizeof(char)); /* local tls type */ | |
214 | elf_local_got_refcounts (abfd) = ((bfd_signed_vma *) | |
215 | bfd_zalloc (abfd, size)); | |
216 | if (elf_local_got_refcounts (abfd) == NULL) | |
217 | return FALSE; | |
218 | elf_s390_local_plt (abfd) | |
219 | = (struct plt_entry*)(elf_local_got_refcounts (abfd) | |
220 | + symtab_hdr->sh_info); | |
221 | elf_s390_local_got_tls_type (abfd) | |
222 | = (char *) (elf_s390_local_plt (abfd) + symtab_hdr->sh_info); | |
223 | ||
224 | return TRUE; | |
225 | } | |
226 | ||
227 | /* Pick ELFOSABI_GNU if IFUNC symbols are used. */ | |
228 | ||
229 | static bfd_boolean | |
230 | elf_s390_add_symbol_hook (bfd *abfd, | |
231 | struct bfd_link_info *info, | |
232 | Elf_Internal_Sym *sym, | |
233 | const char **namep ATTRIBUTE_UNUSED, | |
234 | flagword *flagsp ATTRIBUTE_UNUSED, | |
235 | asection **secp ATTRIBUTE_UNUSED, | |
236 | bfd_vma *valp ATTRIBUTE_UNUSED) | |
237 | { | |
238 | if ((abfd->flags & DYNAMIC) == 0 | |
239 | && ELF_ST_TYPE (sym->st_info) == STT_GNU_IFUNC) | |
240 | elf_tdata (info->output_bfd)->has_gnu_symbols = TRUE; | |
241 | ||
242 | return TRUE; | |
243 | } |