1 /* IBM S/390-specific support for ELF 32 and 64 bit functions
2 Copyright (C) 2000-2018 Free Software Foundation, Inc.
3 Contributed by Andreas Krebbel.
5 This file is part of BFD, the Binary File Descriptor library.
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.
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.
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
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)
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;
33 /* Create sections needed by STT_GNU_IFUNC symbol. */
36 s390_elf_create_ifunc_sections (bfd *abfd, struct bfd_link_info *info)
40 const struct elf_backend_data *bed = get_elf_backend_data (abfd);
41 struct elf_link_hash_table *htab = elf_hash_table (info);
43 if (htab->iplt != NULL)
46 flags = bed->dynamic_sec_flags;
48 if (bfd_link_pic (info))
50 s = bfd_make_section_with_flags (abfd, ".rela.ifunc",
51 flags | SEC_READONLY);
53 || ! bfd_set_section_alignment (abfd, s,
54 bed->s->log_file_align))
59 /* Create .iplt, .rel[a].iplt, and .igot.plt. */
60 s = bfd_make_section_with_flags (abfd, ".iplt",
61 flags | SEC_CODE | SEC_READONLY);
63 || ! bfd_set_section_alignment (abfd, s, bed->plt_alignment))
67 s = bfd_make_section_with_flags (abfd, ".rela.iplt", flags | SEC_READONLY);
69 || ! bfd_set_section_alignment (abfd, s,
70 bed->s->log_file_align))
74 s = bfd_make_section_with_flags (abfd, ".igot.plt", flags);
76 || !bfd_set_section_alignment (abfd, s,
77 bed->s->log_file_align))
85 /* Allocate space in .plt, .got and associated reloc sections for
86 dynamic relocs against a STT_GNU_IFUNC symbol definition. */
89 s390_elf_allocate_ifunc_dyn_relocs (struct bfd_link_info *info,
90 struct elf_link_hash_entry *h)
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;
95 struct elf_dyn_relocs **head = &eh->dyn_relocs;
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;
101 /* Support garbage collection against STT_GNU_IFUNC symbols. */
102 if (h->plt.refcount <= 0 && h->got.refcount <= 0)
104 /* When building shared library, we need to handle the case
105 where it is marked with regular reference, but not non-GOT
106 reference. It may happen if we didn't see STT_GNU_IFUNC
107 symbol at the time when checking relocations. */
108 if (bfd_link_pic (info)
111 for (p = *head; p != NULL; p = p->next)
118 h->got = htab->init_got_offset;
119 h->plt = htab->init_plt_offset;
124 /* Return and discard space for dynamic relocations against it if
125 it is never referenced in a non-shared object. */
128 if (h->plt.refcount > 0
129 || h->got.refcount > 0)
131 h->got = htab->init_got_offset;
132 h->plt = htab->init_plt_offset;
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;
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++;
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. */
154 if (bfd_link_pde (info)
158 h->root.u.def.section = htab->iplt;
159 h->root.u.def.value = h->plt.offset;
160 h->size = PLT_ENTRY_SIZE;
164 if (!bfd_link_pic (info))
167 /* Finally, allocate space. */
171 bfd_size_type count = 0;
178 htab->irelifunc->size += count * RELA_ENTRY_SIZE;
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
184 if (h->got.refcount <= 0
185 || (bfd_link_pic (info)
186 && (h->dynindx == -1 || h->forced_local))
187 || bfd_link_pie (info)
188 || htab->sgot == NULL)
191 h->got.offset = (bfd_vma) -1;
195 h->got.offset = htab->sgot->size;
196 htab->sgot->size += GOT_ENTRY_SIZE;
197 if (bfd_link_pic (info))
198 htab->srelgot->size += RELA_ENTRY_SIZE;
205 elf_s390_allocate_local_syminfo (bfd *abfd, Elf_Internal_Shdr *symtab_hdr)
209 size = symtab_hdr->sh_info;
210 size *= (sizeof (bfd_signed_vma) /* local got */
211 + sizeof (struct plt_entry) /* local plt */
212 + sizeof(char)); /* local tls type */
213 elf_local_got_refcounts (abfd) = ((bfd_signed_vma *)
214 bfd_zalloc (abfd, size));
215 if (elf_local_got_refcounts (abfd) == NULL)
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);
226 /* Whether to sort relocs output by ld -r or ld --emit-relocs, by
227 r_offset. Don't do so for code sections. We want to keep ordering
228 of GDCALL / PLT32DBL for TLS optimizations as is. On the other
229 hand, elf-eh-frame.c processing requires .eh_frame relocs to be
233 elf_s390_elf_sort_relocs_p (asection *sec)
235 return (sec->flags & SEC_CODE) == 0;
238 /* Merge object attributes from IBFD into OBFD. Raise an error if
239 there are conflicting attributes. */
241 elf_s390_merge_obj_attributes (bfd *ibfd, struct bfd_link_info *info)
243 bfd *obfd = info->output_bfd;
244 obj_attribute *in_attr, *in_attrs;
245 obj_attribute *out_attr, *out_attrs;
247 if (!elf_known_obj_attributes_proc (obfd)[0].i)
249 /* This is the first object. Copy the attributes. */
250 _bfd_elf_copy_obj_attributes (ibfd, obfd);
252 /* Use the Tag_null value to indicate the attributes have been
254 elf_known_obj_attributes_proc (obfd)[0].i = 1;
259 in_attrs = elf_known_obj_attributes (ibfd)[OBJ_ATTR_GNU];
260 out_attrs = elf_known_obj_attributes (obfd)[OBJ_ATTR_GNU];
262 /* Check for conflicting Tag_GNU_S390_ABI_Vector attributes and
263 merge non-conflicting ones. */
264 in_attr = &in_attrs[Tag_GNU_S390_ABI_Vector];
265 out_attr = &out_attrs[Tag_GNU_S390_ABI_Vector];
269 /* xgettext:c-format */
270 (_("warning: %pB uses unknown vector ABI %d"), ibfd,
272 else if (out_attr->i > 2)
274 /* xgettext:c-format */
275 (_("warning: %pB uses unknown vector ABI %d"), obfd,
277 else if (in_attr->i != out_attr->i)
279 out_attr->type = ATTR_TYPE_FLAG_INT_VAL;
281 if (in_attr->i && out_attr->i)
283 const char abi_str[3][9] = { "none", "software", "hardware" };
286 /* xgettext:c-format */
287 (_("warning: %pB uses vector %s ABI, %pB uses %s ABI"),
288 ibfd, abi_str[in_attr->i], obfd, abi_str[out_attr->i]);
290 if (in_attr->i > out_attr->i)
291 out_attr->i = in_attr->i;
294 /* Merge Tag_compatibility attributes and any common GNU ones. */
295 _bfd_elf_merge_object_attributes (ibfd, info);