1 // layout.h -- lay out output file sections for gold -*- C++ -*-
11 #include "workqueue.h"
13 #include "stringpool.h"
18 class General_options;
21 class Output_section_data;
23 class Output_section_headers;
26 class Output_data_dynamic;
29 // This task function handles mapping the input sections to output
30 // sections and laying them out in memory.
32 class Layout_task_runner : public Task_function_runner
35 // OPTIONS is the command line options, INPUT_OBJECTS is the list of
36 // input objects, SYMTAB is the symbol table, LAYOUT is the layout
38 Layout_task_runner(const General_options& options,
39 const Input_objects* input_objects,
42 : options_(options), input_objects_(input_objects), symtab_(symtab),
51 Layout_task_runner(const Layout_task_runner&);
52 Layout_task_runner& operator=(const Layout_task_runner&);
54 const General_options& options_;
55 const Input_objects* input_objects_;
56 Symbol_table* symtab_;
60 // This class handles the details of laying out input sections.
65 Layout(const General_options& options);
67 // Given an input section SHNDX, named NAME, with data in SHDR, from
68 // the object file OBJECT, return the output section where this
69 // input section should go. Set *OFFSET to the offset within the
71 template<int size, bool big_endian>
73 layout(Relobj *object, unsigned int shndx, const char* name,
74 const elfcpp::Shdr<size, big_endian>& shdr, off_t* offset);
76 // Add an Output_section_data to the layout. This is used for
77 // special sections like the GOT section.
79 add_output_section_data(const char* name, elfcpp::Elf_Word type,
80 elfcpp::Elf_Xword flags,
81 Output_section_data*);
83 // Create dynamic sections if necessary.
85 create_initial_dynamic_sections(const Input_objects*, Symbol_table*);
87 // Return the Stringpool used for symbol names.
90 { return &this->sympool_; }
92 // Return the Stringpool used for dynamic symbol names and dynamic
96 { return &this->dynpool_; }
98 // Return whether a section is a .gnu.linkonce section, given the
101 is_linkonce(const char* name)
102 { return strncmp(name, ".gnu.linkonce", sizeof(".gnu.linkonce") - 1) == 0; }
104 // Record the signature of a comdat section, and return whether to
105 // include it in the link. The GROUP parameter is true for a
106 // section group signature, false for a signature derived from a
107 // .gnu.linkonce section.
109 add_comdat(const char*, bool group);
111 // Finalize the layout after all the input sections have been added.
113 finalize(const Input_objects*, Symbol_table*);
115 // Return the TLS segment. This will return NULL if there isn't
119 { return this->tls_segment_; }
121 // Return the normal symbol table.
123 symtab_section() const
125 gold_assert(this->symtab_section_ != NULL);
126 return this->symtab_section_;
129 // Return the dynamic symbol table.
131 dynsym_section() const
133 gold_assert(this->dynsym_section_ != NULL);
134 return this->dynsym_section_;
137 // Return the dynamic tags.
140 { return this->dynamic_data_; }
142 // Write out data not associated with an input file or the symbol
145 write_data(const Symbol_table*, const Target*, Output_file*) const;
147 // Return an output section named NAME, or NULL if there is none.
149 find_output_section(const char* name) const;
151 // Return an output segment of type TYPE, with segment flags SET set
152 // and segment flags CLEAR clear. Return NULL if there is none.
154 find_output_segment(elfcpp::PT type, elfcpp::Elf_Word set,
155 elfcpp::Elf_Word clear) const;
157 // The list of segments.
159 typedef std::vector<Output_segment*> Segment_list;
161 // The list of sections not attached to a segment.
163 typedef std::vector<Output_section*> Section_list;
165 // The list of information to write out which is not attached to
166 // either a section or a segment.
167 typedef std::vector<Output_data*> Data_list;
170 Layout(const Layout&);
171 Layout& operator=(const Layout&);
173 // Mapping from .gnu.linkonce section names to output section names.
174 struct Linkonce_mapping
181 static const Linkonce_mapping linkonce_mapping[];
182 static const int linkonce_mapping_count;
184 // Find the first read-only PT_LOAD segment, creating one if
187 find_first_load_seg();
189 // Create the output sections for the symbol table.
191 create_symtab_sections(int size, const Input_objects*, Symbol_table*,
194 // Create the .shstrtab section.
198 // Create the section header table.
199 Output_section_headers*
200 create_shdrs(int size, bool big_endian, off_t*);
202 // Create the dynamic symbol table.
204 create_dynamic_symtab(const Target*, Symbol_table*);
206 // Finish the .dynamic section and PT_DYNAMIC segment.
208 finish_dynamic_section(const Input_objects*, const Symbol_table*);
210 // Create the .interp section and PT_INTERP segment.
212 create_interp(const Target* target);
214 // Return whether to include this section in the link.
215 template<int size, bool big_endian>
217 include_section(Object* object, const char* name,
218 const elfcpp::Shdr<size, big_endian>&);
220 // Return the output section name to use given an input section
221 // name. Set *PLEN to the length of the name. *PLEN must be
222 // initialized to the length of NAME.
224 output_section_name(const char* name, size_t* plen);
226 // Return the output section name to use for a linkonce section
227 // name. PLEN is as for output_section_name.
229 linkonce_output_name(const char* name, size_t* plen);
231 // Return the output section for NAME, TYPE and FLAGS.
233 get_output_section(const char* name, Stringpool::Key name_key,
234 elfcpp::Elf_Word type, elfcpp::Elf_Xword flags);
236 // Create a new Output_section.
238 make_output_section(const char* name, elfcpp::Elf_Word type,
239 elfcpp::Elf_Xword flags);
241 // Set the final file offsets of all the segments.
243 set_segment_offsets(const Target*, Output_segment*, unsigned int* pshndx);
245 // Set the final file offsets and section indices of all the
246 // sections not associated with a segment.
248 set_section_offsets(off_t, unsigned int *pshndx);
250 // Return whether SEG1 comes before SEG2 in the output file.
252 segment_precedes(const Output_segment* seg1, const Output_segment* seg2);
254 // Map from section flags to segment flags.
255 static elfcpp::Elf_Word
256 section_flags_to_segment(elfcpp::Elf_Xword flags);
258 // A mapping used for group signatures.
259 typedef Unordered_map<std::string, bool> Signatures;
261 // Mapping from input section name/type/flags to output section. We
262 // use canonicalized strings here.
264 typedef std::pair<Stringpool::Key,
265 std::pair<elfcpp::Elf_Word, elfcpp::Elf_Xword> > Key;
270 operator()(const Key& k) const;
273 typedef Unordered_map<Key, Output_section*, Hash_key> Section_name_map;
275 // A comparison class for segments.
277 struct Compare_segments
280 operator()(const Output_segment* seg1, const Output_segment* seg2)
281 { return Layout::segment_precedes(seg1, seg2); }
284 // A reference to the options on the command line.
285 const General_options& options_;
286 // The output section names.
287 Stringpool namepool_;
288 // The output symbol names.
290 // The dynamic strings, if needed.
292 // The list of group sections and linkonce sections which we have seen.
293 Signatures signatures_;
294 // The mapping from input section name/type/flags to output sections.
295 Section_name_map section_name_map_;
296 // The list of output segments.
297 Segment_list segment_list_;
298 // The list of output sections.
299 Section_list section_list_;
300 // The list of output sections which are not attached to any output
302 Section_list unattached_section_list_;
303 // The list of unattached Output_data objects which require special
304 // handling because they are not Output_sections.
305 Data_list special_output_list_;
306 // A pointer to the PT_TLS segment if there is one.
307 Output_segment* tls_segment_;
308 // The SHT_SYMTAB output section.
309 Output_section* symtab_section_;
310 // The SHT_DYNSYM output section if there is one.
311 Output_section* dynsym_section_;
312 // The SHT_DYNAMIC output section if there is one.
313 Output_section* dynamic_section_;
314 // The dynamic data which goes into dynamic_section_.
315 Output_data_dynamic* dynamic_data_;
318 // This task handles writing out data which is not part of a section
321 class Write_data_task : public Task
324 Write_data_task(const Layout* layout, const Symbol_table* symtab,
325 const Target* target, Output_file* of,
326 Task_token* final_blocker)
327 : layout_(layout), symtab_(symtab), target_(target), of_(of),
328 final_blocker_(final_blocker)
331 // The standard Task methods.
334 is_runnable(Workqueue*);
343 const Layout* layout_;
344 const Symbol_table* symtab_;
345 const Target* target_;
347 Task_token* final_blocker_;
350 // This task handles writing out the global symbols.
352 class Write_symbols_task : public Task
355 Write_symbols_task(const Symbol_table* symtab, const Target* target,
356 const Stringpool* sympool, const Stringpool* dynpool,
357 Output_file* of, Task_token* final_blocker)
358 : symtab_(symtab), target_(target), sympool_(sympool), dynpool_(dynpool),
359 of_(of), final_blocker_(final_blocker)
362 // The standard Task methods.
365 is_runnable(Workqueue*);
374 const Symbol_table* symtab_;
375 const Target* target_;
376 const Stringpool* sympool_;
377 const Stringpool* dynpool_;
379 Task_token* final_blocker_;
382 // This task function handles closing the file.
384 class Close_task_runner : public Task_function_runner
387 Close_task_runner(Output_file* of)
391 // Run the operation.
399 // A small helper function to align an address.
402 align_address(uint64_t address, uint64_t addralign)
405 address = (address + addralign - 1) &~ (addralign - 1);
409 } // End namespace gold.
411 #endif // !defined(GOLD_LAYOUT_H)