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
);
232 // Return whether to include this section in the link.
233 template<int size
, bool big_endian
>
235 include_section(Object
* object
, const char* name
,
236 const elfcpp::Shdr
<size
, big_endian
>&);
238 // Return the output section name to use given an input section
239 // name. Set *PLEN to the length of the name. *PLEN must be
240 // initialized to the length of NAME.
242 output_section_name(const char* name
, size_t* plen
);
244 // Return the output section name to use for a linkonce section
245 // name. PLEN is as for output_section_name.
247 linkonce_output_name(const char* name
, size_t* plen
);
249 // Return the output section for NAME, TYPE and FLAGS.
251 get_output_section(const char* name
, Stringpool::Key name_key
,
252 elfcpp::Elf_Word type
, elfcpp::Elf_Xword flags
);
254 // Create a new Output_section.
256 make_output_section(const char* name
, elfcpp::Elf_Word type
,
257 elfcpp::Elf_Xword flags
);
259 // Set the final file offsets of all the segments.
261 set_segment_offsets(const Target
*, Output_segment
*, unsigned int* pshndx
);
263 // Set the final file offsets and section indexes of all the
264 // sections not associated with a segment.
266 set_section_offsets(off_t
, unsigned int *pshndx
);
268 // Return whether SEG1 comes before SEG2 in the output file.
270 segment_precedes(const Output_segment
* seg1
, const Output_segment
* seg2
);
272 // Map from section flags to segment flags.
273 static elfcpp::Elf_Word
274 section_flags_to_segment(elfcpp::Elf_Xword flags
);
276 // A mapping used for group signatures.
277 typedef Unordered_map
<std::string
, bool> Signatures
;
279 // Mapping from input section name/type/flags to output section. We
280 // use canonicalized strings here.
282 typedef std::pair
<Stringpool::Key
,
283 std::pair
<elfcpp::Elf_Word
, elfcpp::Elf_Xword
> > Key
;
288 operator()(const Key
& k
) const;
291 typedef Unordered_map
<Key
, Output_section
*, Hash_key
> Section_name_map
;
293 // A comparison class for segments.
295 struct Compare_segments
298 operator()(const Output_segment
* seg1
, const Output_segment
* seg2
)
299 { return Layout::segment_precedes(seg1
, seg2
); }
302 // A reference to the options on the command line.
303 const General_options
& options_
;
304 // The output section names.
305 Stringpool namepool_
;
306 // The output symbol names.
308 // The dynamic strings, if needed.
310 // The list of group sections and linkonce sections which we have seen.
311 Signatures signatures_
;
312 // The mapping from input section name/type/flags to output sections.
313 Section_name_map section_name_map_
;
314 // The list of output segments.
315 Segment_list segment_list_
;
316 // The list of output sections.
317 Section_list section_list_
;
318 // The list of output sections which are not attached to any output
320 Section_list unattached_section_list_
;
321 // The list of unattached Output_data objects which require special
322 // handling because they are not Output_sections.
323 Data_list special_output_list_
;
324 // A pointer to the PT_TLS segment if there is one.
325 Output_segment
* tls_segment_
;
326 // The SHT_SYMTAB output section.
327 Output_section
* symtab_section_
;
328 // The SHT_DYNSYM output section if there is one.
329 Output_section
* dynsym_section_
;
330 // The SHT_DYNAMIC output section if there is one.
331 Output_section
* dynamic_section_
;
332 // The dynamic data which goes into dynamic_section_.
333 Output_data_dynamic
* dynamic_data_
;
336 // This task handles writing out data which is not part of a section
339 class Write_data_task
: public Task
342 Write_data_task(const Layout
* layout
, const Symbol_table
* symtab
,
343 const Target
* target
, Output_file
* of
,
344 Task_token
* final_blocker
)
345 : layout_(layout
), symtab_(symtab
), target_(target
), of_(of
),
346 final_blocker_(final_blocker
)
349 // The standard Task methods.
352 is_runnable(Workqueue
*);
361 const Layout
* layout_
;
362 const Symbol_table
* symtab_
;
363 const Target
* target_
;
365 Task_token
* final_blocker_
;
368 // This task handles writing out the global symbols.
370 class Write_symbols_task
: public Task
373 Write_symbols_task(const Symbol_table
* symtab
, const Target
* target
,
374 const Stringpool
* sympool
, const Stringpool
* dynpool
,
375 Output_file
* of
, Task_token
* final_blocker
)
376 : symtab_(symtab
), target_(target
), sympool_(sympool
), dynpool_(dynpool
),
377 of_(of
), final_blocker_(final_blocker
)
380 // The standard Task methods.
383 is_runnable(Workqueue
*);
392 const Symbol_table
* symtab_
;
393 const Target
* target_
;
394 const Stringpool
* sympool_
;
395 const Stringpool
* dynpool_
;
397 Task_token
* final_blocker_
;
400 // This task function handles closing the file.
402 class Close_task_runner
: public Task_function_runner
405 Close_task_runner(Output_file
* of
)
409 // Run the operation.
417 // A small helper function to align an address.
420 align_address(uint64_t address
, uint64_t addralign
)
423 address
= (address
+ addralign
- 1) &~ (addralign
- 1);
427 } // End namespace gold.
429 #endif // !defined(GOLD_LAYOUT_H)