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.
6 This file is part of BFD, the Binary File Descriptor library.
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.
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.
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
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
)
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;
34 /* Create sections needed by STT_GNU_IFUNC symbol. */
37 s390_elf_create_ifunc_sections (bfd
*abfd
, struct bfd_link_info
*info
)
41 const struct elf_backend_data
*bed
= get_elf_backend_data (abfd
);
42 struct elf_link_hash_table
*htab
= elf_hash_table (info
);
44 if (htab
->iplt
!= NULL
)
47 flags
= bed
->dynamic_sec_flags
;
51 s
= bfd_make_section_with_flags (abfd
, ".rela.ifunc",
52 flags
| SEC_READONLY
);
54 || ! bfd_set_section_alignment (abfd
, s
,
55 bed
->s
->log_file_align
))
60 /* Create .iplt, .rel[a].iplt, and .igot.plt. */
61 s
= bfd_make_section_with_flags (abfd
, ".iplt",
62 flags
| SEC_CODE
| SEC_READONLY
);
64 || ! bfd_set_section_alignment (abfd
, s
, bed
->plt_alignment
))
68 s
= bfd_make_section_with_flags (abfd
, ".rela.iplt", flags
| SEC_READONLY
);
70 || ! bfd_set_section_alignment (abfd
, s
,
71 bed
->s
->log_file_align
))
75 s
= bfd_make_section_with_flags (abfd
, ".igot.plt", flags
);
77 || !bfd_set_section_alignment (abfd
, s
,
78 bed
->s
->log_file_align
))
86 /* Allocate space in .plt, .got and associated reloc sections for
87 dynamic relocs against a STT_GNU_IFUNC symbol definition. */
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
)
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
;
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
;
102 /* Support garbage collection against STT_GNU_IFUNC symbols. */
103 if (h
->plt
.refcount
<= 0 && h
->got
.refcount
<= 0)
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. */
112 for (p
= *head
; p
!= NULL
; p
= p
->next
)
119 h
->got
= htab
->init_got_offset
;
120 h
->plt
= htab
->init_plt_offset
;
125 /* Return and discard space for dynamic relocations against it if
126 it is never referenced in a non-shared object. */
129 if (h
->plt
.refcount
> 0
130 || h
->got
.refcount
> 0)
132 h
->got
= htab
->init_got_offset
;
133 h
->plt
= htab
->init_plt_offset
;
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
;
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
++;
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
)
157 h
->root
.u
.def
.section
= htab
->iplt
;
158 h
->root
.u
.def
.value
= h
->plt
.offset
;
159 h
->size
= PLT_ENTRY_SIZE
;
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
)
168 /* Finally, allocate space. */
172 bfd_size_type count
= 0;
179 htab
->irelifunc
->size
+= count
* RELA_ENTRY_SIZE
;
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
185 if (h
->got
.refcount
<= 0
187 && (h
->dynindx
== -1 || h
->forced_local
))
188 || (info
->executable
&& info
->shared
)
189 || htab
->sgot
== NULL
)
192 h
->got
.offset
= (bfd_vma
) -1;
196 h
->got
.offset
= htab
->sgot
->size
;
197 htab
->sgot
->size
+= GOT_ENTRY_SIZE
;
199 htab
->srelgot
->size
+= RELA_ENTRY_SIZE
;
206 elf_s390_allocate_local_syminfo (bfd
*abfd
, Elf_Internal_Shdr
*symtab_hdr
)
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
)
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
);
227 /* Pick ELFOSABI_GNU if IFUNC symbols are used. */
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
)
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
;
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