1 // layout.h -- lay out output file sections for gold -*- C++ -*-
11 #include "workqueue.h"
14 #include "stringpool.h"
19 class General_options;
22 class Output_section_data;
24 class Output_section_headers;
27 class Output_data_dynamic;
30 // This task function handles mapping the input sections to output
31 // sections and laying them out in memory.
33 class Layout_task_runner : public Task_function_runner
36 // OPTIONS is the command line options, INPUT_OBJECTS is the list of
37 // input objects, SYMTAB is the symbol table, LAYOUT is the layout
39 Layout_task_runner(const General_options& options,
40 const Input_objects* input_objects,
43 : options_(options), input_objects_(input_objects), symtab_(symtab),
52 Layout_task_runner(const Layout_task_runner&);
53 Layout_task_runner& operator=(const Layout_task_runner&);
55 const General_options& options_;
56 const Input_objects* input_objects_;
57 Symbol_table* symtab_;
61 // This class handles the details of laying out input sections.
66 Layout(const General_options& options);
68 // Given an input section SHNDX, named NAME, with data in SHDR, from
69 // the object file OBJECT, return the output section where this
70 // input section should go. Set *OFFSET to the offset within the
72 template<int size, bool big_endian>
74 layout(Relobj *object, unsigned int shndx, const char* name,
75 const elfcpp::Shdr<size, big_endian>& shdr, off_t* offset);
77 // Add an Output_section_data to the layout. This is used for
78 // special sections like the GOT section.
80 add_output_section_data(const char* name, elfcpp::Elf_Word type,
81 elfcpp::Elf_Xword flags,
82 Output_section_data*);
84 // Create dynamic sections if necessary.
86 create_initial_dynamic_sections(const Input_objects*, Symbol_table*);
88 // Return the Stringpool used for symbol names.
91 { return &this->sympool_; }
93 // Return the Stringpool used for dynamic symbol names and dynamic
97 { return &this->dynpool_; }
99 // Return whether a section is a .gnu.linkonce section, given the
102 is_linkonce(const char* name)
103 { return strncmp(name, ".gnu.linkonce", sizeof(".gnu.linkonce") - 1) == 0; }
105 // Record the signature of a comdat section, and return whether to
106 // include it in the link. The GROUP parameter is true for a
107 // section group signature, false for a signature derived from a
108 // .gnu.linkonce section.
110 add_comdat(const char*, bool group);
112 // Finalize the layout after all the input sections have been added.
114 finalize(const Input_objects*, Symbol_table*);
116 // Return the TLS segment. This will return NULL if there isn't
120 { return this->tls_segment_; }
122 // Return the normal symbol table.
124 symtab_section() const
126 gold_assert(this->symtab_section_ != NULL);
127 return this->symtab_section_;
130 // Return the dynamic symbol table.
132 dynsym_section() const
134 gold_assert(this->dynsym_section_ != NULL);
135 return this->dynsym_section_;
138 // Return the dynamic tags.
141 { return this->dynamic_data_; }
143 // Write out data not associated with an input file or the symbol
146 write_data(const Symbol_table*, const Target*, Output_file*) const;
148 // Return an output section named NAME, or NULL if there is none.
150 find_output_section(const char* name) const;
152 // Return an output segment of type TYPE, with segment flags SET set
153 // and segment flags CLEAR clear. Return NULL if there is none.
155 find_output_segment(elfcpp::PT type, elfcpp::Elf_Word set,
156 elfcpp::Elf_Word clear) const;
158 // The list of segments.
160 typedef std::vector<Output_segment*> Segment_list;
162 // The list of sections not attached to a segment.
164 typedef std::vector<Output_section*> Section_list;
166 // The list of information to write out which is not attached to
167 // either a section or a segment.
168 typedef std::vector<Output_data*> Data_list;
171 Layout(const Layout&);
172 Layout& operator=(const Layout&);
174 // Mapping from .gnu.linkonce section names to output section names.
175 struct Linkonce_mapping
182 static const Linkonce_mapping linkonce_mapping[];
183 static const int linkonce_mapping_count;
185 // Find the first read-only PT_LOAD segment, creating one if
188 find_first_load_seg();
190 // Create the output sections for the symbol table.
192 create_symtab_sections(int size, const Input_objects*, Symbol_table*,
195 // Create the .shstrtab section.
199 // Create the section header table.
200 Output_section_headers*
201 create_shdrs(int size, bool big_endian, off_t*);
203 // Create the dynamic symbol table.
205 create_dynamic_symtab(const Target*, Symbol_table*, Output_section** pdynstr,
206 unsigned int* plocal_dynamic_count,
207 std::vector<Symbol*>* pdynamic_symbols,
210 // Finish the .dynamic section and PT_DYNAMIC segment.
212 finish_dynamic_section(const Input_objects*, const Symbol_table*);
214 // Create the .interp section and PT_INTERP segment.
216 create_interp(const Target* target);
218 // Create the version sections.
220 create_version_sections(const Target*, const Versions*,
221 unsigned int local_symcount,
222 const std::vector<Symbol*>& dynamic_symbols,
223 const Output_section* dynstr);
225 template<int size, bool big_endian>
227 sized_create_version_sections(const Versions* versions,
228 unsigned int local_symcount,
229 const std::vector<Symbol*>& dynamic_symbols,
230 const Output_section* dynstr
233 // Return whether to include this section in the link.
234 template<int size, bool big_endian>
236 include_section(Object* object, const char* name,
237 const elfcpp::Shdr<size, big_endian>&);
239 // Return the output section name to use given an input section
240 // name. Set *PLEN to the length of the name. *PLEN must be
241 // initialized to the length of NAME.
243 output_section_name(const char* name, size_t* plen);
245 // Return the output section name to use for a linkonce section
246 // name. PLEN is as for output_section_name.
248 linkonce_output_name(const char* name, size_t* plen);
250 // Return the output section for NAME, TYPE and FLAGS.
252 get_output_section(const char* name, Stringpool::Key name_key,
253 elfcpp::Elf_Word type, elfcpp::Elf_Xword flags);
255 // Create a new Output_section.
257 make_output_section(const char* name, elfcpp::Elf_Word type,
258 elfcpp::Elf_Xword flags);
260 // Set the final file offsets of all the segments.
262 set_segment_offsets(const Target*, Output_segment*, unsigned int* pshndx);
264 // Set the final file offsets and section indexes of all the
265 // sections not associated with a segment.
267 set_section_offsets(off_t, unsigned int *pshndx);
269 // Return whether SEG1 comes before SEG2 in the output file.
271 segment_precedes(const Output_segment* seg1, const Output_segment* seg2);
273 // Map from section flags to segment flags.
274 static elfcpp::Elf_Word
275 section_flags_to_segment(elfcpp::Elf_Xword flags);
277 // A mapping used for group signatures.
278 typedef Unordered_map<std::string, bool> Signatures;
280 // Mapping from input section name/type/flags to output section. We
281 // use canonicalized strings here.
283 typedef std::pair<Stringpool::Key,
284 std::pair<elfcpp::Elf_Word, elfcpp::Elf_Xword> > Key;
289 operator()(const Key& k) const;
292 typedef Unordered_map<Key, Output_section*, Hash_key> Section_name_map;
294 // A comparison class for segments.
296 struct Compare_segments
299 operator()(const Output_segment* seg1, const Output_segment* seg2)
300 { return Layout::segment_precedes(seg1, seg2); }
303 // A reference to the options on the command line.
304 const General_options& options_;
305 // The output section names.
306 Stringpool namepool_;
307 // The output symbol names.
309 // The dynamic strings, if needed.
311 // The list of group sections and linkonce sections which we have seen.
312 Signatures signatures_;
313 // The mapping from input section name/type/flags to output sections.
314 Section_name_map section_name_map_;
315 // The list of output segments.
316 Segment_list segment_list_;
317 // The list of output sections.
318 Section_list section_list_;
319 // The list of output sections which are not attached to any output
321 Section_list unattached_section_list_;
322 // The list of unattached Output_data objects which require special
323 // handling because they are not Output_sections.
324 Data_list special_output_list_;
325 // A pointer to the PT_TLS segment if there is one.
326 Output_segment* tls_segment_;
327 // The SHT_SYMTAB output section.
328 Output_section* symtab_section_;
329 // The SHT_DYNSYM output section if there is one.
330 Output_section* dynsym_section_;
331 // The SHT_DYNAMIC output section if there is one.
332 Output_section* dynamic_section_;
333 // The dynamic data which goes into dynamic_section_.
334 Output_data_dynamic* dynamic_data_;
337 // This task handles writing out data which is not part of a section
340 class Write_data_task : public Task
343 Write_data_task(const Layout* layout, const Symbol_table* symtab,
344 const Target* target, Output_file* of,
345 Task_token* final_blocker)
346 : layout_(layout), symtab_(symtab), target_(target), of_(of),
347 final_blocker_(final_blocker)
350 // The standard Task methods.
353 is_runnable(Workqueue*);
362 const Layout* layout_;
363 const Symbol_table* symtab_;
364 const Target* target_;
366 Task_token* final_blocker_;
369 // This task handles writing out the global symbols.
371 class Write_symbols_task : public Task
374 Write_symbols_task(const Symbol_table* symtab, const Target* target,
375 const Stringpool* sympool, const Stringpool* dynpool,
376 Output_file* of, Task_token* final_blocker)
377 : symtab_(symtab), target_(target), sympool_(sympool), dynpool_(dynpool),
378 of_(of), final_blocker_(final_blocker)
381 // The standard Task methods.
384 is_runnable(Workqueue*);
393 const Symbol_table* symtab_;
394 const Target* target_;
395 const Stringpool* sympool_;
396 const Stringpool* dynpool_;
398 Task_token* final_blocker_;
401 // This task function handles closing the file.
403 class Close_task_runner : public Task_function_runner
406 Close_task_runner(Output_file* of)
410 // Run the operation.
418 // A small helper function to align an address.
421 align_address(uint64_t address, uint64_t addralign)
424 address = (address + addralign - 1) &~ (addralign - 1);
428 } // End namespace gold.
430 #endif // !defined(GOLD_LAYOUT_H)