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[binutils.git] / gold / copy-relocs.cc
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1 // copy-relocs.cc -- handle COPY relocations for gold.
3 // Copyright 2006, 2007, 2008 Free Software Foundation, Inc.
4 // Written by Ian Lance Taylor <iant@google.com>.
6 // This file is part of gold.
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,
21 // MA 02110-1301, USA.
23 #include "gold.h"
25 #include "symtab.h"
26 #include "copy-relocs.h"
28 namespace gold
31 // Copy_relocs::Copy_reloc_entry methods.
33 // Emit the reloc if appropriate.
35 template<int sh_type, int size, bool big_endian>
36 void
37 Copy_relocs<sh_type, size, big_endian>::Copy_reloc_entry::emit(
38 Output_data_reloc<sh_type, true, size, big_endian>* reloc_section)
40 // If the symbol is no longer defined in a dynamic object, then we
41 // emitted a COPY relocation, and we do not want to emit this
42 // dynamic relocation.
43 if (this->sym_->is_from_dynobj())
44 reloc_section->add_global(this->sym_, this->reloc_type_,
45 this->output_section_, this->relobj_,
46 this->shndx_, this->address_,
47 this->addend_);
50 // Copy_relocs methods.
52 // Handle a relocation against a symbol which may force us to generate
53 // a COPY reloc.
55 template<int sh_type, int size, bool big_endian>
56 void
57 Copy_relocs<sh_type, size, big_endian>::copy_reloc(
58 Symbol_table* symtab,
59 Layout* layout,
60 Sized_symbol<size>* sym,
61 Sized_relobj<size, big_endian>* object,
62 unsigned int shndx,
63 Output_section *output_section,
64 const Reloc& rel,
65 Output_data_reloc<sh_type, true, size, big_endian>* reloc_section)
67 if (this->need_copy_reloc(sym, object, shndx))
68 this->emit_copy_reloc(symtab, layout, sym, reloc_section);
69 else
71 // We may not need a COPY relocation. Save this relocation to
72 // possibly be emitted later.
73 this->save(sym, object, shndx, output_section, rel);
77 // Return whether we need a COPY reloc for a relocation against SYM.
78 // The relocation is begin applied to section SHNDX in OBJECT.
80 template<int sh_type, int size, bool big_endian>
81 bool
82 Copy_relocs<sh_type, size, big_endian>::need_copy_reloc(
83 Sized_symbol<size>* sym,
84 Sized_relobj<size, big_endian>* object,
85 unsigned int shndx) const
87 // FIXME: Handle -z nocopyrelocs.
89 if (sym->symsize() == 0)
90 return false;
92 // If this is a readonly section, then we need a COPY reloc.
93 // Otherwise we can use a dynamic reloc. Note that calling
94 // section_flags here can be slow, as the information is not cached;
95 // fortunately we shouldn't see too many potential COPY relocs.
96 if ((object->section_flags(shndx) & elfcpp::SHF_WRITE) == 0)
97 return true;
99 return false;
102 // Emit a COPY relocation for SYM.
104 template<int sh_type, int size, bool big_endian>
105 void
106 Copy_relocs<sh_type, size, big_endian>::emit_copy_reloc(
107 Symbol_table* symtab,
108 Layout* layout,
109 Sized_symbol<size>* sym,
110 Output_data_reloc<sh_type, true, size, big_endian>* reloc_section)
112 typename elfcpp::Elf_types<size>::Elf_WXword symsize = sym->symsize();
114 // There is no defined way to determine the required alignment of
115 // the symbol. We know that the symbol is defined in a dynamic
116 // object. We start with the alignment of the section in which it
117 // is defined; presumably we do not require an alignment larger than
118 // that. Then we reduce that alignment if the symbol is not aligned
119 // within the section.
120 gold_assert(sym->is_from_dynobj());
121 bool is_ordinary;
122 unsigned int shndx = sym->shndx(&is_ordinary);
123 gold_assert(is_ordinary);
124 typename elfcpp::Elf_types<size>::Elf_WXword addralign =
125 sym->object()->section_addralign(shndx);
127 typename Sized_symbol<size>::Value_type value = sym->value();
128 while ((value & (addralign - 1)) != 0)
129 addralign >>= 1;
131 if (this->dynbss_ == NULL)
133 this->dynbss_ = new Output_data_space(addralign, "** dynbss");
134 layout->add_output_section_data(".bss",
135 elfcpp::SHT_NOBITS,
136 elfcpp::SHF_ALLOC | elfcpp::SHF_WRITE,
137 this->dynbss_);
140 Output_data_space* dynbss = this->dynbss_;
142 if (addralign > dynbss->addralign())
143 dynbss->set_space_alignment(addralign);
145 section_size_type dynbss_size =
146 convert_to_section_size_type(dynbss->current_data_size());
147 dynbss_size = align_address(dynbss_size, addralign);
148 section_size_type offset = dynbss_size;
149 dynbss->set_current_data_size(dynbss_size + symsize);
151 // Define the symbol as being copied.
152 symtab->define_with_copy_reloc(sym, dynbss, offset);
154 // Add the COPY relocation to the dynamic reloc section.
155 this->add_copy_reloc(sym, offset, reloc_section);
158 // Add a COPY relocation for SYM to RELOC_SECTION.
160 template<int sh_type, int size, bool big_endian>
161 void
162 Copy_relocs<sh_type, size, big_endian>::add_copy_reloc(
163 Symbol* sym,
164 section_size_type offset,
165 Output_data_reloc<sh_type, true, size, big_endian>* reloc_section)
167 reloc_section->add_global(sym, this->copy_reloc_type_, this->dynbss_,
168 offset, 0);
171 // Save a relocation to possibly be emitted later.
173 template<int sh_type, int size, bool big_endian>
174 void
175 Copy_relocs<sh_type, size, big_endian>::save(
176 Symbol* sym,
177 Sized_relobj<size, big_endian>* object,
178 unsigned int shndx,
179 Output_section* output_section,
180 const Reloc& rel)
182 unsigned int reloc_type = elfcpp::elf_r_type<size>(rel.get_r_info());
183 typename elfcpp::Elf_types<size>::Elf_Addr addend =
184 Reloc_types<sh_type, size, big_endian>::get_reloc_addend_noerror(&rel);
185 this->entries_.push_back(Copy_reloc_entry(sym, reloc_type, object, shndx,
186 output_section, rel.get_r_offset(),
187 addend));
190 // Emit any saved relocs.
192 template<int sh_type, int size, bool big_endian>
193 void
194 Copy_relocs<sh_type, size, big_endian>::emit(
195 Output_data_reloc<sh_type, true, size, big_endian>* reloc_section)
197 for (typename Copy_reloc_entries::iterator p = this->entries_.begin();
198 p != this->entries_.end();
199 ++p)
200 p->emit(reloc_section);
202 // We no longer need the saved information.
203 this->entries_.clear();
206 // Instantiate the templates we need.
208 #ifdef HAVE_TARGET_32_LITTLE
209 template
210 class Copy_relocs<elfcpp::SHT_REL, 32, false>;
212 template
213 class Copy_relocs<elfcpp::SHT_RELA, 32, false>;
214 #endif
216 #ifdef HAVE_TARGET_32_BIG
217 template
218 class Copy_relocs<elfcpp::SHT_REL, 32, true>;
220 template
221 class Copy_relocs<elfcpp::SHT_RELA, 32, true>;
222 #endif
224 #ifdef HAVE_TARGET_64_LITTLE
225 template
226 class Copy_relocs<elfcpp::SHT_REL, 64, false>;
228 template
229 class Copy_relocs<elfcpp::SHT_RELA, 64, false>;
230 #endif
232 #ifdef HAVE_TARGET_64_BIG
233 template
234 class Copy_relocs<elfcpp::SHT_REL, 64, true>;
236 template
237 class Copy_relocs<elfcpp::SHT_RELA, 64, true>;
238 #endif
240 } // End namespace gold.