1 // gold.cc -- main linker functions
3 // Copyright 2006, 2007, 2008, 2009 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.
30 #include "libiberty.h"
34 #include "workqueue.h"
35 #include "dirsearch.h"
48 const char* program_name
;
51 gold_exit(bool status
)
53 if (parameters
!= NULL
54 && parameters
->options_valid()
55 && parameters
->options().has_plugins())
56 parameters
->options().plugins()->cleanup();
57 if (!status
&& parameters
!= NULL
&& parameters
->options_valid())
58 unlink_if_ordinary(parameters
->options().output_file_name());
59 exit(status
? EXIT_SUCCESS
: EXIT_FAILURE
);
65 // We are out of memory, so try hard to print a reasonable message.
66 // Note that we don't try to translate this message, since the
67 // translation process itself will require memory.
69 // LEN only exists to avoid a pointless warning when write is
70 // declared with warn_use_result, as when compiling with
71 // -D_USE_FORTIFY on GNU/Linux. Casting to void does not appear to
72 // work, at least not with gcc 4.3.0.
74 ssize_t len
= write(2, program_name
, strlen(program_name
));
77 const char* const s
= ": out of memory\n";
78 len
= write(2, s
, strlen(s
));
83 // Handle an unreachable case.
86 do_gold_unreachable(const char* filename
, int lineno
, const char* function
)
88 fprintf(stderr
, _("%s: internal error in %s, at %s:%d\n"),
89 program_name
, function
, filename
, lineno
);
93 // This class arranges to run the functions done in the middle of the
94 // link. It is just a closure.
96 class Middle_runner
: public Task_function_runner
99 Middle_runner(const General_options
& options
,
100 const Input_objects
* input_objects
,
101 Symbol_table
* symtab
,
102 Layout
* layout
, Mapfile
* mapfile
)
103 : options_(options
), input_objects_(input_objects
), symtab_(symtab
),
104 layout_(layout
), mapfile_(mapfile
)
108 run(Workqueue
*, const Task
*);
111 const General_options
& options_
;
112 const Input_objects
* input_objects_
;
113 Symbol_table
* symtab_
;
119 Middle_runner::run(Workqueue
* workqueue
, const Task
* task
)
121 queue_middle_tasks(this->options_
, task
, this->input_objects_
, this->symtab_
,
122 this->layout_
, workqueue
, this->mapfile_
);
125 // This class arranges the tasks to process the relocs for garbage collection.
127 class Gc_runner
: public Task_function_runner
130 Gc_runner(const General_options
& options
,
131 const Input_objects
* input_objects
,
132 Symbol_table
* symtab
,
133 Layout
* layout
, Mapfile
* mapfile
)
134 : options_(options
), input_objects_(input_objects
), symtab_(symtab
),
135 layout_(layout
), mapfile_(mapfile
)
139 run(Workqueue
*, const Task
*);
142 const General_options
& options_
;
143 const Input_objects
* input_objects_
;
144 Symbol_table
* symtab_
;
150 Gc_runner::run(Workqueue
* workqueue
, const Task
* task
)
152 queue_middle_gc_tasks(this->options_
, task
, this->input_objects_
,
153 this->symtab_
, this->layout_
, workqueue
,
157 // Queue up the initial set of tasks for this link job.
160 queue_initial_tasks(const General_options
& options
,
161 Dirsearch
& search_path
,
162 const Command_line
& cmdline
,
163 Workqueue
* workqueue
, Input_objects
* input_objects
,
164 Symbol_table
* symtab
, Layout
* layout
, Mapfile
* mapfile
)
166 if (cmdline
.begin() == cmdline
.end())
168 if (options
.printed_version())
170 gold_fatal(_("no input files"));
173 int thread_count
= options
.thread_count_initial();
174 if (thread_count
== 0)
175 thread_count
= cmdline
.number_of_input_files();
176 workqueue
->set_thread_count(thread_count
);
178 // Read the input files. We have to add the symbols to the symbol
179 // table in order. We do this by creating a separate blocker for
180 // each input file. We associate the blocker with the following
181 // input file, to give us a convenient place to delete it.
182 Task_token
* this_blocker
= NULL
;
183 for (Command_line::const_iterator p
= cmdline
.begin();
187 Task_token
* next_blocker
= new Task_token(true);
188 next_blocker
->add_blocker();
189 workqueue
->queue(new Read_symbols(input_objects
, symtab
, layout
,
190 &search_path
, 0, mapfile
, &*p
, NULL
,
191 this_blocker
, next_blocker
));
192 this_blocker
= next_blocker
;
195 if (options
.has_plugins())
197 Task_token
* next_blocker
= new Task_token(true);
198 next_blocker
->add_blocker();
199 workqueue
->queue(new Plugin_hook(options
, input_objects
, symtab
, layout
,
200 &search_path
, mapfile
, this_blocker
,
202 this_blocker
= next_blocker
;
205 if (parameters
->options().relocatable()
206 && parameters
->options().gc_sections())
207 gold_error(_("cannot mix -r with garbage collection"));
209 if (parameters
->options().gc_sections())
211 workqueue
->queue(new Task_function(new Gc_runner(options
,
217 "Task_function Gc_runner"));
221 workqueue
->queue(new Task_function(new Middle_runner(options
,
227 "Task_function Middle_runner"));
231 // Queue up a set of tasks to be done before queueing the middle set
232 // of tasks. This is only necessary when garbage collection
233 // (--gc-sections) of unused sections is desired. The relocs are read
234 // and processed here early to determine the garbage sections before the
235 // relocs can be scanned in later tasks.
238 queue_middle_gc_tasks(const General_options
& options
,
240 const Input_objects
* input_objects
,
241 Symbol_table
* symtab
,
243 Workqueue
* workqueue
,
246 // Read_relocs for all the objects must be done and processed to find
247 // unused sections before any scanning of the relocs can take place.
248 Task_token
* blocker
= new Task_token(true);
249 Task_token
* symtab_lock
= new Task_token(false);
250 for (Input_objects::Relobj_iterator p
= input_objects
->relobj_begin();
251 p
!= input_objects
->relobj_end();
254 // We can read and process the relocations in any order.
255 blocker
->add_blocker();
256 workqueue
->queue(new Read_relocs(options
, symtab
, layout
, *p
,
257 symtab_lock
, blocker
));
260 Task_token
* this_blocker
= new Task_token(true);
261 workqueue
->queue(new Task_function(new Middle_runner(options
,
267 "Task_function Middle_runner"));
270 // Queue up the middle set of tasks. These are the tasks which run
271 // after all the input objects have been found and all the symbols
272 // have been read, but before we lay out the output file.
275 queue_middle_tasks(const General_options
& options
,
277 const Input_objects
* input_objects
,
278 Symbol_table
* symtab
,
280 Workqueue
* workqueue
,
283 // Add any symbols named with -u options to the symbol table.
284 symtab
->add_undefined_symbols_from_command_line();
286 // If garbage collection was chosen, relocs have been read and processed
287 // at this point by pre_middle_tasks. Layout can then be done for all
289 if (parameters
->options().gc_sections())
291 // Find the start symbol if any.
293 if (parameters
->options().entry())
294 start_sym
= symtab
->lookup(parameters
->options().entry());
296 start_sym
= symtab
->lookup("_start");
297 if (start_sym
!=NULL
)
300 unsigned int shndx
= start_sym
->shndx(&is_ordinary
);
303 symtab
->gc()->worklist().push(
304 Section_id(start_sym
->object(), shndx
));
307 // Symbols named with -u should not be considered garbage.
308 symtab
->gc_mark_undef_symbols();
309 gold_assert(symtab
->gc() != NULL
);
310 // Do a transitive closure on all references to determine the worklist.
311 symtab
->gc()->do_transitive_closure();
312 // Call do_layout again to determine the output_sections for all
313 // referenced input sections.
314 for (Input_objects::Relobj_iterator p
= input_objects
->relobj_begin();
315 p
!= input_objects
->relobj_end();
318 (*p
)->layout(symtab
, layout
, NULL
);
321 // Layout deferred objects due to plugins.
322 if (parameters
->options().has_plugins())
324 Plugin_manager
* plugins
= parameters
->options().plugins();
325 gold_assert(plugins
!= NULL
);
326 plugins
->layout_deferred_objects();
328 if (parameters
->options().gc_sections())
330 for (Input_objects::Relobj_iterator p
= input_objects
->relobj_begin();
331 p
!= input_objects
->relobj_end();
334 // Update the value of output_section stored in rd.
335 Read_relocs_data
*rd
= (*p
)->get_relocs_data();
336 for (Read_relocs_data::Relocs_list::iterator q
= rd
->relocs
.begin();
337 q
!= rd
->relocs
.end();
340 q
->output_section
= (*p
)->output_section(q
->data_shndx
);
341 q
->needs_special_offset_handling
=
342 (*p
)->is_output_section_offset_invalid(q
->data_shndx
);
347 // We have to support the case of not seeing any input objects, and
348 // generate an empty file. Existing builds depend on being able to
349 // pass an empty archive to the linker and get an empty object file
350 // out. In order to do this we need to use a default target.
351 if (input_objects
->number_of_input_objects() == 0)
352 set_parameters_target(¶meters
->default_target());
354 int thread_count
= options
.thread_count_middle();
355 if (thread_count
== 0)
356 thread_count
= std::max(2, input_objects
->number_of_input_objects());
357 workqueue
->set_thread_count(thread_count
);
359 // Now we have seen all the input files.
360 const bool doing_static_link
= (!input_objects
->any_dynamic()
361 && !parameters
->options().shared());
362 set_parameters_doing_static_link(doing_static_link
);
363 if (!doing_static_link
&& options
.is_static())
365 // We print out just the first .so we see; there may be others.
366 gold_assert(input_objects
->dynobj_begin() != input_objects
->dynobj_end());
367 gold_error(_("cannot mix -static with dynamic object %s"),
368 (*input_objects
->dynobj_begin())->name().c_str());
370 if (!doing_static_link
&& parameters
->options().relocatable())
371 gold_fatal(_("cannot mix -r with dynamic object %s"),
372 (*input_objects
->dynobj_begin())->name().c_str());
373 if (!doing_static_link
374 && options
.oformat_enum() != General_options::OBJECT_FORMAT_ELF
)
375 gold_fatal(_("cannot use non-ELF output format with dynamic object %s"),
376 (*input_objects
->dynobj_begin())->name().c_str());
378 if (is_debugging_enabled(DEBUG_SCRIPT
))
379 layout
->script_options()->print(stderr
);
381 // For each dynamic object, record whether we've seen all the
382 // dynamic objects that it depends upon.
383 input_objects
->check_dynamic_dependencies();
385 // See if any of the input definitions violate the One Definition Rule.
386 // TODO: if this is too slow, do this as a task, rather than inline.
387 symtab
->detect_odr_violations(task
, options
.output_file_name());
389 // Create any output sections required by any linker script.
390 layout
->create_script_sections();
392 // Define some sections and symbols needed for a dynamic link. This
393 // handles some cases we want to see before we read the relocs.
394 layout
->create_initial_dynamic_sections(symtab
);
396 // Define symbols from any linker scripts.
397 layout
->define_script_symbols(symtab
);
399 // Attach sections to segments.
400 layout
->attach_sections_to_segments();
402 if (!parameters
->options().relocatable())
404 // Predefine standard symbols.
405 define_standard_symbols(symtab
, layout
);
407 // Define __start and __stop symbols for output sections where
409 layout
->define_section_symbols(symtab
);
412 // Make sure we have symbols for any required group signatures.
413 layout
->define_group_signatures(symtab
);
415 Task_token
* blocker
= new Task_token(true);
416 Task_token
* symtab_lock
= new Task_token(false);
418 // If doing garbage collection, the relocations have already been read.
419 // Otherwise, read and scan the relocations.
420 if (parameters
->options().gc_sections())
422 for (Input_objects::Relobj_iterator p
= input_objects
->relobj_begin();
423 p
!= input_objects
->relobj_end();
426 blocker
->add_blocker();
427 workqueue
->queue(new Scan_relocs(options
, symtab
, layout
, *p
,
428 (*p
)->get_relocs_data(),symtab_lock
, blocker
));
433 // Read the relocations of the input files. We do this to find
434 // which symbols are used by relocations which require a GOT and/or
435 // a PLT entry, or a COPY reloc. When we implement garbage
436 // collection we will do it here by reading the relocations in a
437 // breadth first search by references.
439 // We could also read the relocations during the first pass, and
440 // mark symbols at that time. That is how the old GNU linker works.
441 // Doing that is more complex, since we may later decide to discard
442 // some of the sections, and thus change our minds about the types
443 // of references made to the symbols.
444 for (Input_objects::Relobj_iterator p
= input_objects
->relobj_begin();
445 p
!= input_objects
->relobj_end();
448 // We can read and process the relocations in any order. But we
449 // only want one task to write to the symbol table at a time.
450 // So we queue up a task for each object to read the
451 // relocations. That task will in turn queue a task to wait
452 // until it can write to the symbol table.
453 blocker
->add_blocker();
454 workqueue
->queue(new Read_relocs(options
, symtab
, layout
, *p
,
455 symtab_lock
, blocker
));
459 // Allocate common symbols. This requires write access to the
460 // symbol table, but is independent of the relocation processing.
461 if (parameters
->options().define_common())
463 blocker
->add_blocker();
464 workqueue
->queue(new Allocate_commons_task(symtab
, layout
, mapfile
,
465 symtab_lock
, blocker
));
468 // When all those tasks are complete, we can start laying out the
470 // TODO(csilvers): figure out a more principled way to get the target
471 Target
* target
= const_cast<Target
*>(¶meters
->target());
472 workqueue
->queue(new Task_function(new Layout_task_runner(options
,
479 "Task_function Layout_task_runner"));
482 // Queue up the final set of tasks. This is called at the end of
486 queue_final_tasks(const General_options
& options
,
487 const Input_objects
* input_objects
,
488 const Symbol_table
* symtab
,
490 Workqueue
* workqueue
,
493 int thread_count
= options
.thread_count_final();
494 if (thread_count
== 0)
495 thread_count
= std::max(2, input_objects
->number_of_input_objects());
496 workqueue
->set_thread_count(thread_count
);
498 bool any_postprocessing_sections
= layout
->any_postprocessing_sections();
500 // Use a blocker to wait until all the input sections have been
502 Task_token
* input_sections_blocker
= NULL
;
503 if (!any_postprocessing_sections
)
504 input_sections_blocker
= new Task_token(true);
506 // Use a blocker to block any objects which have to wait for the
507 // output sections to complete before they can apply relocations.
508 Task_token
* output_sections_blocker
= new Task_token(true);
510 // Use a blocker to block the final cleanup task.
511 Task_token
* final_blocker
= new Task_token(true);
513 // Queue a task to write out the symbol table.
514 final_blocker
->add_blocker();
515 workqueue
->queue(new Write_symbols_task(layout
,
523 // Queue a task to write out the output sections.
524 output_sections_blocker
->add_blocker();
525 final_blocker
->add_blocker();
526 workqueue
->queue(new Write_sections_task(layout
, of
, output_sections_blocker
,
529 // Queue a task to write out everything else.
530 final_blocker
->add_blocker();
531 workqueue
->queue(new Write_data_task(layout
, symtab
, of
, final_blocker
));
533 // Queue a task for each input object to relocate the sections and
534 // write out the local symbols.
535 for (Input_objects::Relobj_iterator p
= input_objects
->relobj_begin();
536 p
!= input_objects
->relobj_end();
539 if (input_sections_blocker
!= NULL
)
540 input_sections_blocker
->add_blocker();
541 final_blocker
->add_blocker();
542 workqueue
->queue(new Relocate_task(options
, symtab
, layout
, *p
, of
,
543 input_sections_blocker
,
544 output_sections_blocker
,
548 // Queue a task to write out the output sections which depend on
549 // input sections. If there are any sections which require
550 // postprocessing, then we need to do this last, since it may resize
552 if (!any_postprocessing_sections
)
554 final_blocker
->add_blocker();
555 Task
* t
= new Write_after_input_sections_task(layout
, of
,
556 input_sections_blocker
,
562 Task_token
*new_final_blocker
= new Task_token(true);
563 new_final_blocker
->add_blocker();
564 Task
* t
= new Write_after_input_sections_task(layout
, of
,
568 final_blocker
= new_final_blocker
;
571 // Queue a task to close the output file. This will be blocked by
573 workqueue
->queue(new Task_function(new Close_task_runner(&options
, layout
,
576 "Task_function Close_task_runner"));
579 } // End namespace gold.