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470b557a | 1 | /* IBM S/390-specific support for ELF 32 and 64 bit functions |
219d1afa | 2 | Copyright (C) 2000-2018 Free Software Foundation, Inc. |
470b557a AK |
3 | Contributed by Andreas Krebbel. |
4 | ||
5 | This file is part of BFD, the Binary File Descriptor library. | |
6 | ||
7 | This program is free software; you can redistribute it and/or modify | |
8 | it under the terms of the GNU General Public License as published by | |
9 | the Free Software Foundation; either version 3 of the License, or | |
10 | (at your option) any later version. | |
11 | ||
12 | This program is distributed in the hope that it will be useful, | |
13 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
15 | GNU General Public License for more details. | |
16 | ||
17 | You should have received a copy of the GNU General Public License | |
18 | along with this program; if not, write to the Free Software | |
19 | Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA | |
20 | 02110-1301, USA. */ | |
21 | ||
22 | ||
23 | /* Return TRUE if H is an IFUNC symbol. Simply checking for the | |
24 | symbol type might not be enough since it might get changed to | |
25 | STT_FUNC for pointer equality reasons. */ | |
26 | static inline bfd_boolean | |
27 | s390_is_ifunc_symbol_p (struct elf_link_hash_entry *h) | |
28 | { | |
29 | struct elf_s390_link_hash_entry *eh = (struct elf_s390_link_hash_entry*)h; | |
30 | return h->type == STT_GNU_IFUNC || eh->ifunc_resolver_address != 0; | |
31 | } | |
32 | ||
33 | /* Create sections needed by STT_GNU_IFUNC symbol. */ | |
34 | ||
35 | static bfd_boolean | |
36 | s390_elf_create_ifunc_sections (bfd *abfd, struct bfd_link_info *info) | |
37 | { | |
38 | flagword flags; | |
39 | asection *s; | |
40 | const struct elf_backend_data *bed = get_elf_backend_data (abfd); | |
41 | struct elf_link_hash_table *htab = elf_hash_table (info); | |
42 | ||
43 | if (htab->iplt != NULL) | |
44 | return TRUE; | |
45 | ||
46 | flags = bed->dynamic_sec_flags; | |
47 | ||
0e1862bb | 48 | if (bfd_link_pic (info)) |
470b557a AK |
49 | { |
50 | s = bfd_make_section_with_flags (abfd, ".rela.ifunc", | |
51 | flags | SEC_READONLY); | |
52 | if (s == NULL | |
53 | || ! bfd_set_section_alignment (abfd, s, | |
54 | bed->s->log_file_align)) | |
55 | return FALSE; | |
56 | htab->irelifunc = s; | |
57 | } | |
58 | ||
59 | /* Create .iplt, .rel[a].iplt, and .igot.plt. */ | |
60 | s = bfd_make_section_with_flags (abfd, ".iplt", | |
61 | flags | SEC_CODE | SEC_READONLY); | |
62 | if (s == NULL | |
63 | || ! bfd_set_section_alignment (abfd, s, bed->plt_alignment)) | |
64 | return FALSE; | |
65 | htab->iplt = s; | |
66 | ||
67 | s = bfd_make_section_with_flags (abfd, ".rela.iplt", flags | SEC_READONLY); | |
68 | if (s == NULL | |
69 | || ! bfd_set_section_alignment (abfd, s, | |
70 | bed->s->log_file_align)) | |
71 | return FALSE; | |
72 | htab->irelplt = s; | |
73 | ||
74 | s = bfd_make_section_with_flags (abfd, ".igot.plt", flags); | |
75 | if (s == NULL | |
76 | || !bfd_set_section_alignment (abfd, s, | |
77 | bed->s->log_file_align)) | |
78 | return FALSE; | |
79 | htab->igotplt = s; | |
80 | ||
81 | return TRUE; | |
82 | } | |
83 | ||
84 | ||
85 | /* Allocate space in .plt, .got and associated reloc sections for | |
86 | dynamic relocs against a STT_GNU_IFUNC symbol definition. */ | |
87 | ||
88 | static bfd_boolean | |
89 | s390_elf_allocate_ifunc_dyn_relocs (struct bfd_link_info *info, | |
61643fba | 90 | struct elf_link_hash_entry *h) |
470b557a AK |
91 | { |
92 | struct elf_dyn_relocs *p; | |
93 | struct elf_link_hash_table *htab; | |
94 | struct elf_s390_link_hash_entry *eh = (struct elf_s390_link_hash_entry*)h; | |
61643fba | 95 | struct elf_dyn_relocs **head = &eh->dyn_relocs; |
470b557a AK |
96 | |
97 | htab = elf_hash_table (info); | |
98 | eh->ifunc_resolver_address = h->root.u.def.value; | |
99 | eh->ifunc_resolver_section = h->root.u.def.section; | |
100 | ||
101 | /* Support garbage collection against STT_GNU_IFUNC symbols. */ | |
102 | if (h->plt.refcount <= 0 && h->got.refcount <= 0) | |
103 | { | |
104 | /* When building shared library, we need to handle the case | |
07d6d2b8 | 105 | where it is marked with regular reference, but not non-GOT |
470b557a AK |
106 | reference. It may happen if we didn't see STT_GNU_IFUNC |
107 | symbol at the time when checking relocations. */ | |
0e1862bb | 108 | if (bfd_link_pic (info) |
470b557a AK |
109 | && !h->non_got_ref |
110 | && h->ref_regular) | |
111 | for (p = *head; p != NULL; p = p->next) | |
112 | if (p->count) | |
113 | { | |
114 | h->non_got_ref = 1; | |
115 | goto keep; | |
116 | } | |
117 | ||
118 | h->got = htab->init_got_offset; | |
119 | h->plt = htab->init_plt_offset; | |
120 | *head = NULL; | |
121 | return TRUE; | |
122 | } | |
123 | ||
124 | /* Return and discard space for dynamic relocations against it if | |
125 | it is never referenced in a non-shared object. */ | |
126 | if (!h->ref_regular) | |
127 | { | |
128 | if (h->plt.refcount > 0 | |
129 | || h->got.refcount > 0) | |
130 | abort (); | |
131 | h->got = htab->init_got_offset; | |
132 | h->plt = htab->init_plt_offset; | |
133 | *head = NULL; | |
134 | return TRUE; | |
135 | } | |
136 | ||
137 | keep: | |
138 | /* Without checking h->plt.refcount here we allocate a PLT slot. | |
139 | When setting plt.refcount in check_relocs it might not have been | |
140 | known that this will be an IFUNC symol. */ | |
141 | h->plt.offset = htab->iplt->size; | |
142 | h->needs_plt = 1; | |
143 | htab->iplt->size += PLT_ENTRY_SIZE; | |
144 | htab->igotplt->size += GOT_ENTRY_SIZE; | |
145 | htab->irelplt->size += RELA_ENTRY_SIZE; | |
146 | htab->irelplt->reloc_count++; | |
147 | ||
148 | /* In order to make pointer equality work with IFUNC symbols defined | |
149 | in a non-PIE executable and referenced in a shared lib, we turn | |
150 | the symbol into a STT_FUNC symbol and make the symbol value to | |
151 | point to the IPLT slot. That way the referencing shared lib will | |
152 | always get the PLT slot address when resolving the respective | |
153 | R_390_GLOB_DAT/R_390_64 relocs on that symbol. */ | |
3cbc1e5e | 154 | if (bfd_link_pde (info) |
0e1862bb L |
155 | && h->def_regular |
156 | && h->ref_dynamic) | |
470b557a AK |
157 | { |
158 | h->root.u.def.section = htab->iplt; | |
159 | h->root.u.def.value = h->plt.offset; | |
160 | h->size = PLT_ENTRY_SIZE; | |
161 | h->type = STT_FUNC; | |
162 | } | |
163 | ||
d7ab4911 | 164 | if (!bfd_link_pic (info)) |
470b557a AK |
165 | *head = NULL; |
166 | ||
167 | /* Finally, allocate space. */ | |
168 | p = *head; | |
169 | if (p != NULL) | |
170 | { | |
171 | bfd_size_type count = 0; | |
172 | do | |
173 | { | |
174 | count += p->count; | |
175 | p = p->next; | |
176 | } | |
177 | while (p != NULL); | |
178 | htab->irelifunc->size += count * RELA_ENTRY_SIZE; | |
179 | } | |
180 | ||
181 | /* Decide whether the got.iplt slot can be used. This has to be | |
182 | avoided if the values in the GOT slots could differ for pointer | |
183 | equality reasons. */ | |
184 | if (h->got.refcount <= 0 | |
0e1862bb | 185 | || (bfd_link_pic (info) |
470b557a | 186 | && (h->dynindx == -1 || h->forced_local)) |
3cbc1e5e | 187 | || bfd_link_pie (info) |
470b557a AK |
188 | || htab->sgot == NULL) |
189 | { | |
190 | /* Use .got.iplt. */ | |
191 | h->got.offset = (bfd_vma) -1; | |
192 | } | |
193 | else | |
194 | { | |
195 | h->got.offset = htab->sgot->size; | |
196 | htab->sgot->size += GOT_ENTRY_SIZE; | |
0e1862bb | 197 | if (bfd_link_pic (info)) |
470b557a AK |
198 | htab->srelgot->size += RELA_ENTRY_SIZE; |
199 | } | |
200 | ||
201 | return TRUE; | |
202 | } | |
203 | ||
204 | static bfd_boolean | |
205 | elf_s390_allocate_local_syminfo (bfd *abfd, Elf_Internal_Shdr *symtab_hdr) | |
206 | { | |
207 | bfd_size_type size; | |
208 | ||
209 | size = symtab_hdr->sh_info; | |
07d6d2b8 AM |
210 | size *= (sizeof (bfd_signed_vma) /* local got */ |
211 | + sizeof (struct plt_entry) /* local plt */ | |
212 | + sizeof(char)); /* local tls type */ | |
470b557a AK |
213 | elf_local_got_refcounts (abfd) = ((bfd_signed_vma *) |
214 | bfd_zalloc (abfd, size)); | |
215 | if (elf_local_got_refcounts (abfd) == NULL) | |
216 | return FALSE; | |
217 | elf_s390_local_plt (abfd) | |
218 | = (struct plt_entry*)(elf_local_got_refcounts (abfd) | |
219 | + symtab_hdr->sh_info); | |
220 | elf_s390_local_got_tls_type (abfd) | |
221 | = (char *) (elf_s390_local_plt (abfd) + symtab_hdr->sh_info); | |
222 | ||
223 | return TRUE; | |
224 | } | |
225 | ||
226 | /* Pick ELFOSABI_GNU if IFUNC symbols are used. */ | |
227 | ||
228 | static bfd_boolean | |
229 | elf_s390_add_symbol_hook (bfd *abfd, | |
230 | struct bfd_link_info *info, | |
231 | Elf_Internal_Sym *sym, | |
232 | const char **namep ATTRIBUTE_UNUSED, | |
233 | flagword *flagsp ATTRIBUTE_UNUSED, | |
234 | asection **secp ATTRIBUTE_UNUSED, | |
235 | bfd_vma *valp ATTRIBUTE_UNUSED) | |
236 | { | |
a43942db | 237 | if (ELF_ST_TYPE (sym->st_info) == STT_GNU_IFUNC |
f1885d1e AM |
238 | && (abfd->flags & DYNAMIC) == 0 |
239 | && bfd_get_flavour (info->output_bfd) == bfd_target_elf_flavour) | |
a43942db | 240 | elf_tdata (info->output_bfd)->has_gnu_symbols |= elf_gnu_symbol_ifunc; |
470b557a AK |
241 | |
242 | return TRUE; | |
243 | } | |
b9005ba7 AK |
244 | |
245 | /* Whether to sort relocs output by ld -r or ld --emit-relocs, by | |
246 | r_offset. Don't do so for code sections. We want to keep ordering | |
247 | of GDCALL / PLT32DBL for TLS optimizations as is. On the other | |
248 | hand, elf-eh-frame.c processing requires .eh_frame relocs to be | |
249 | sorted. */ | |
250 | ||
251 | static bfd_boolean | |
252 | elf_s390_elf_sort_relocs_p (asection *sec) | |
253 | { | |
254 | return (sec->flags & SEC_CODE) == 0; | |
255 | } | |
643f7afb AK |
256 | |
257 | /* Merge object attributes from IBFD into OBFD. Raise an error if | |
258 | there are conflicting attributes. */ | |
259 | static bfd_boolean | |
50e03d47 | 260 | elf_s390_merge_obj_attributes (bfd *ibfd, struct bfd_link_info *info) |
643f7afb | 261 | { |
50e03d47 | 262 | bfd *obfd = info->output_bfd; |
643f7afb AK |
263 | obj_attribute *in_attr, *in_attrs; |
264 | obj_attribute *out_attr, *out_attrs; | |
265 | ||
266 | if (!elf_known_obj_attributes_proc (obfd)[0].i) | |
267 | { | |
268 | /* This is the first object. Copy the attributes. */ | |
269 | _bfd_elf_copy_obj_attributes (ibfd, obfd); | |
270 | ||
271 | /* Use the Tag_null value to indicate the attributes have been | |
272 | initialized. */ | |
273 | elf_known_obj_attributes_proc (obfd)[0].i = 1; | |
274 | ||
275 | return TRUE; | |
276 | } | |
277 | ||
278 | in_attrs = elf_known_obj_attributes (ibfd)[OBJ_ATTR_GNU]; | |
279 | out_attrs = elf_known_obj_attributes (obfd)[OBJ_ATTR_GNU]; | |
280 | ||
281 | /* Check for conflicting Tag_GNU_S390_ABI_Vector attributes and | |
282 | merge non-conflicting ones. */ | |
283 | in_attr = &in_attrs[Tag_GNU_S390_ABI_Vector]; | |
284 | out_attr = &out_attrs[Tag_GNU_S390_ABI_Vector]; | |
285 | ||
286 | if (in_attr->i > 2) | |
287 | _bfd_error_handler | |
695344c0 | 288 | /* xgettext:c-format */ |
871b3ab2 | 289 | (_("Warning: %pB uses unknown vector ABI %d"), ibfd, |
643f7afb AK |
290 | in_attr->i); |
291 | else if (out_attr->i > 2) | |
292 | _bfd_error_handler | |
695344c0 | 293 | /* xgettext:c-format */ |
871b3ab2 | 294 | (_("Warning: %pB uses unknown vector ABI %d"), obfd, |
643f7afb AK |
295 | out_attr->i); |
296 | else if (in_attr->i != out_attr->i) | |
297 | { | |
298 | out_attr->type = ATTR_TYPE_FLAG_INT_VAL; | |
299 | ||
300 | if (in_attr->i && out_attr->i) | |
301 | { | |
302 | const char abi_str[3][9] = { "none", "software", "hardware" }; | |
303 | ||
304 | _bfd_error_handler | |
695344c0 | 305 | /* xgettext:c-format */ |
871b3ab2 | 306 | (_("Warning: %pB uses vector %s ABI, %pB uses %s ABI"), |
c08bb8dd | 307 | ibfd, abi_str[in_attr->i], obfd, abi_str[out_attr->i]); |
643f7afb AK |
308 | } |
309 | if (in_attr->i > out_attr->i) | |
310 | out_attr->i = in_attr->i; | |
311 | } | |
312 | ||
313 | /* Merge Tag_compatibility attributes and any common GNU ones. */ | |
50e03d47 | 314 | _bfd_elf_merge_object_attributes (ibfd, info); |
643f7afb AK |
315 | |
316 | return TRUE; | |
317 | } |