| // gold.cc -- main linker functions |
| |
| // Copyright 2006, 2007, 2008, 2009, 2010 Free Software Foundation, Inc. |
| // Written by Ian Lance Taylor <iant@google.com>. |
| |
| // This file is part of gold. |
| |
| // This program is free software; you can redistribute it and/or modify |
| // it under the terms of the GNU General Public License as published by |
| // the Free Software Foundation; either version 3 of the License, or |
| // (at your option) any later version. |
| |
| // This program is distributed in the hope that it will be useful, |
| // but WITHOUT ANY WARRANTY; without even the implied warranty of |
| // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| // GNU General Public License for more details. |
| |
| // You should have received a copy of the GNU General Public License |
| // along with this program; if not, write to the Free Software |
| // Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, |
| // MA 02110-1301, USA. |
| |
| #include "gold.h" |
| |
| #include <cstdlib> |
| #include <cstdio> |
| #include <cstring> |
| #include <unistd.h> |
| #include <algorithm> |
| #include "libiberty.h" |
| |
| #include "options.h" |
| #include "debug.h" |
| #include "workqueue.h" |
| #include "dirsearch.h" |
| #include "readsyms.h" |
| #include "symtab.h" |
| #include "common.h" |
| #include "object.h" |
| #include "layout.h" |
| #include "reloc.h" |
| #include "defstd.h" |
| #include "plugin.h" |
| #include "gc.h" |
| #include "icf.h" |
| #include "incremental.h" |
| |
| namespace gold |
| { |
| |
| const char* program_name; |
| |
| void |
| gold_exit(bool status) |
| { |
| if (parameters != NULL |
| && parameters->options_valid() |
| && parameters->options().has_plugins()) |
| parameters->options().plugins()->cleanup(); |
| if (!status && parameters != NULL && parameters->options_valid()) |
| unlink_if_ordinary(parameters->options().output_file_name()); |
| exit(status ? EXIT_SUCCESS : EXIT_FAILURE); |
| } |
| |
| void |
| gold_nomem() |
| { |
| // We are out of memory, so try hard to print a reasonable message. |
| // Note that we don't try to translate this message, since the |
| // translation process itself will require memory. |
| |
| // LEN only exists to avoid a pointless warning when write is |
| // declared with warn_use_result, as when compiling with |
| // -D_USE_FORTIFY on GNU/Linux. Casting to void does not appear to |
| // work, at least not with gcc 4.3.0. |
| |
| ssize_t len = write(2, program_name, strlen(program_name)); |
| if (len >= 0) |
| { |
| const char* const s = ": out of memory\n"; |
| len = write(2, s, strlen(s)); |
| } |
| gold_exit(false); |
| } |
| |
| // Handle an unreachable case. |
| |
| void |
| do_gold_unreachable(const char* filename, int lineno, const char* function) |
| { |
| fprintf(stderr, _("%s: internal error in %s, at %s:%d\n"), |
| program_name, function, filename, lineno); |
| gold_exit(false); |
| } |
| |
| // This class arranges to run the functions done in the middle of the |
| // link. It is just a closure. |
| |
| class Middle_runner : public Task_function_runner |
| { |
| public: |
| Middle_runner(const General_options& options, |
| const Input_objects* input_objects, |
| Symbol_table* symtab, |
| Layout* layout, Mapfile* mapfile) |
| : options_(options), input_objects_(input_objects), symtab_(symtab), |
| layout_(layout), mapfile_(mapfile) |
| { } |
| |
| void |
| run(Workqueue*, const Task*); |
| |
| private: |
| const General_options& options_; |
| const Input_objects* input_objects_; |
| Symbol_table* symtab_; |
| Layout* layout_; |
| Mapfile* mapfile_; |
| }; |
| |
| void |
| Middle_runner::run(Workqueue* workqueue, const Task* task) |
| { |
| queue_middle_tasks(this->options_, task, this->input_objects_, this->symtab_, |
| this->layout_, workqueue, this->mapfile_); |
| } |
| |
| // This class arranges the tasks to process the relocs for garbage collection. |
| |
| class Gc_runner : public Task_function_runner |
| { |
| public: |
| Gc_runner(const General_options& options, |
| const Input_objects* input_objects, |
| Symbol_table* symtab, |
| Layout* layout, Mapfile* mapfile) |
| : options_(options), input_objects_(input_objects), symtab_(symtab), |
| layout_(layout), mapfile_(mapfile) |
| { } |
| |
| void |
| run(Workqueue*, const Task*); |
| |
| private: |
| const General_options& options_; |
| const Input_objects* input_objects_; |
| Symbol_table* symtab_; |
| Layout* layout_; |
| Mapfile* mapfile_; |
| }; |
| |
| void |
| Gc_runner::run(Workqueue* workqueue, const Task* task) |
| { |
| queue_middle_gc_tasks(this->options_, task, this->input_objects_, |
| this->symtab_, this->layout_, workqueue, |
| this->mapfile_); |
| } |
| |
| // Queue up the initial set of tasks for this link job. |
| |
| void |
| queue_initial_tasks(const General_options& options, |
| Dirsearch& search_path, |
| const Command_line& cmdline, |
| Workqueue* workqueue, Input_objects* input_objects, |
| Symbol_table* symtab, Layout* layout, Mapfile* mapfile) |
| { |
| if (cmdline.begin() == cmdline.end()) |
| { |
| if (options.printed_version()) |
| gold_exit(true); |
| gold_fatal(_("no input files")); |
| } |
| |
| int thread_count = options.thread_count_initial(); |
| if (thread_count == 0) |
| thread_count = cmdline.number_of_input_files(); |
| workqueue->set_thread_count(thread_count); |
| |
| if (cmdline.options().incremental()) |
| { |
| Incremental_checker incremental_checker( |
| parameters->options().output_file_name(), |
| layout->incremental_inputs()); |
| if (incremental_checker.can_incrementally_link_output_file()) |
| { |
| // TODO: remove when incremental linking implemented. |
| printf("Incremental linking might be possible " |
| "(not implemented yet)\n"); |
| } |
| // TODO: If we decide on an incremental build, fewer tasks |
| // should be scheduled. |
| } |
| |
| // Read the input files. We have to add the symbols to the symbol |
| // table in order. We do this by creating a separate blocker for |
| // each input file. We associate the blocker with the following |
| // input file, to give us a convenient place to delete it. |
| Task_token* this_blocker = NULL; |
| for (Command_line::const_iterator p = cmdline.begin(); |
| p != cmdline.end(); |
| ++p) |
| { |
| Task_token* next_blocker = new Task_token(true); |
| next_blocker->add_blocker(); |
| workqueue->queue(new Read_symbols(input_objects, symtab, layout, |
| &search_path, 0, mapfile, &*p, NULL, |
| NULL, this_blocker, next_blocker)); |
| this_blocker = next_blocker; |
| } |
| |
| if (options.has_plugins()) |
| { |
| Task_token* next_blocker = new Task_token(true); |
| next_blocker->add_blocker(); |
| workqueue->queue(new Plugin_hook(options, input_objects, symtab, layout, |
| &search_path, mapfile, this_blocker, |
| next_blocker)); |
| this_blocker = next_blocker; |
| } |
| |
| if (parameters->options().relocatable() |
| && (parameters->options().gc_sections() |
| || parameters->options().icf_enabled())) |
| gold_error(_("cannot mix -r with --gc-sections or --icf")); |
| |
| if (parameters->options().gc_sections() |
| || parameters->options().icf_enabled()) |
| { |
| workqueue->queue(new Task_function(new Gc_runner(options, |
| input_objects, |
| symtab, |
| layout, |
| mapfile), |
| this_blocker, |
| "Task_function Gc_runner")); |
| } |
| else |
| { |
| workqueue->queue(new Task_function(new Middle_runner(options, |
| input_objects, |
| symtab, |
| layout, |
| mapfile), |
| this_blocker, |
| "Task_function Middle_runner")); |
| } |
| } |
| |
| // Queue up a set of tasks to be done before queueing the middle set |
| // of tasks. This is only necessary when garbage collection |
| // (--gc-sections) of unused sections is desired. The relocs are read |
| // and processed here early to determine the garbage sections before the |
| // relocs can be scanned in later tasks. |
| |
| void |
| queue_middle_gc_tasks(const General_options& options, |
| const Task* , |
| const Input_objects* input_objects, |
| Symbol_table* symtab, |
| Layout* layout, |
| Workqueue* workqueue, |
| Mapfile* mapfile) |
| { |
| // Read_relocs for all the objects must be done and processed to find |
| // unused sections before any scanning of the relocs can take place. |
| Task_token* this_blocker = NULL; |
| for (Input_objects::Relobj_iterator p = input_objects->relobj_begin(); |
| p != input_objects->relobj_end(); |
| ++p) |
| { |
| Task_token* next_blocker = new Task_token(true); |
| next_blocker->add_blocker(); |
| workqueue->queue(new Read_relocs(symtab, layout, *p, this_blocker, |
| next_blocker)); |
| this_blocker = next_blocker; |
| } |
| |
| // If we are given only archives in input, we have no regular |
| // objects and THIS_BLOCKER is NULL here. Create a dummy |
| // blocker here so that we can run the middle tasks immediately. |
| if (this_blocker == NULL) |
| { |
| gold_assert(input_objects->number_of_relobjs() == 0); |
| this_blocker = new Task_token(true); |
| } |
| |
| workqueue->queue(new Task_function(new Middle_runner(options, |
| input_objects, |
| symtab, |
| layout, |
| mapfile), |
| this_blocker, |
| "Task_function Middle_runner")); |
| } |
| |
| // Queue up the middle set of tasks. These are the tasks which run |
| // after all the input objects have been found and all the symbols |
| // have been read, but before we lay out the output file. |
| |
| void |
| queue_middle_tasks(const General_options& options, |
| const Task* task, |
| const Input_objects* input_objects, |
| Symbol_table* symtab, |
| Layout* layout, |
| Workqueue* workqueue, |
| Mapfile* mapfile) |
| { |
| // Add any symbols named with -u options to the symbol table. |
| symtab->add_undefined_symbols_from_command_line(); |
| |
| // If garbage collection was chosen, relocs have been read and processed |
| // at this point by pre_middle_tasks. Layout can then be done for all |
| // objects. |
| if (parameters->options().gc_sections()) |
| { |
| // Find the start symbol if any. |
| Symbol* start_sym; |
| if (parameters->options().entry()) |
| start_sym = symtab->lookup(parameters->options().entry()); |
| else |
| start_sym = symtab->lookup("_start"); |
| if (start_sym != NULL) |
| { |
| bool is_ordinary; |
| unsigned int shndx = start_sym->shndx(&is_ordinary); |
| if (is_ordinary) |
| { |
| symtab->gc()->worklist().push( |
| Section_id(start_sym->object(), shndx)); |
| } |
| } |
| // Symbols named with -u should not be considered garbage. |
| symtab->gc_mark_undef_symbols(); |
| gold_assert(symtab->gc() != NULL); |
| // Do a transitive closure on all references to determine the worklist. |
| symtab->gc()->do_transitive_closure(); |
| } |
| |
| // If identical code folding (--icf) is chosen it makes sense to do it |
| // only after garbage collection (--gc-sections) as we do not want to |
| // be folding sections that will be garbage. |
| if (parameters->options().icf_enabled()) |
| { |
| symtab->icf()->find_identical_sections(input_objects, symtab); |
| } |
| |
| // Call Object::layout for the second time to determine the |
| // output_sections for all referenced input sections. When |
| // --gc-sections or --icf is turned on, Object::layout is |
| // called twice. It is called the first time when the |
| // symbols are added. |
| if (parameters->options().gc_sections() |
| || parameters->options().icf_enabled()) |
| { |
| for (Input_objects::Relobj_iterator p = input_objects->relobj_begin(); |
| p != input_objects->relobj_end(); |
| ++p) |
| { |
| (*p)->layout(symtab, layout, NULL); |
| } |
| } |
| |
| // Layout deferred objects due to plugins. |
| if (parameters->options().has_plugins()) |
| { |
| Plugin_manager* plugins = parameters->options().plugins(); |
| gold_assert(plugins != NULL); |
| plugins->layout_deferred_objects(); |
| } |
| |
| if (parameters->options().gc_sections() |
| || parameters->options().icf_enabled()) |
| { |
| for (Input_objects::Relobj_iterator p = input_objects->relobj_begin(); |
| p != input_objects->relobj_end(); |
| ++p) |
| { |
| // Update the value of output_section stored in rd. |
| Read_relocs_data *rd = (*p)->get_relocs_data(); |
| for (Read_relocs_data::Relocs_list::iterator q = rd->relocs.begin(); |
| q != rd->relocs.end(); |
| ++q) |
| { |
| q->output_section = (*p)->output_section(q->data_shndx); |
| q->needs_special_offset_handling = |
| (*p)->is_output_section_offset_invalid(q->data_shndx); |
| } |
| } |
| } |
| |
| // We have to support the case of not seeing any input objects, and |
| // generate an empty file. Existing builds depend on being able to |
| // pass an empty archive to the linker and get an empty object file |
| // out. In order to do this we need to use a default target. |
| if (input_objects->number_of_input_objects() == 0) |
| parameters_force_valid_target(); |
| |
| int thread_count = options.thread_count_middle(); |
| if (thread_count == 0) |
| thread_count = std::max(2, input_objects->number_of_input_objects()); |
| workqueue->set_thread_count(thread_count); |
| |
| // Now we have seen all the input files. |
| const bool doing_static_link = |
| (!input_objects->any_dynamic() |
| && !parameters->options().output_is_position_independent()); |
| set_parameters_doing_static_link(doing_static_link); |
| if (!doing_static_link && options.is_static()) |
| { |
| // We print out just the first .so we see; there may be others. |
| gold_assert(input_objects->dynobj_begin() != input_objects->dynobj_end()); |
| gold_error(_("cannot mix -static with dynamic object %s"), |
| (*input_objects->dynobj_begin())->name().c_str()); |
| } |
| if (!doing_static_link && parameters->options().relocatable()) |
| gold_fatal(_("cannot mix -r with dynamic object %s"), |
| (*input_objects->dynobj_begin())->name().c_str()); |
| if (!doing_static_link |
| && options.oformat_enum() != General_options::OBJECT_FORMAT_ELF) |
| gold_fatal(_("cannot use non-ELF output format with dynamic object %s"), |
| (*input_objects->dynobj_begin())->name().c_str()); |
| |
| if (parameters->options().relocatable()) |
| { |
| Input_objects::Relobj_iterator p = input_objects->relobj_begin(); |
| if (p != input_objects->relobj_end()) |
| { |
| bool uses_split_stack = (*p)->uses_split_stack(); |
| for (++p; p != input_objects->relobj_end(); ++p) |
| { |
| if ((*p)->uses_split_stack() != uses_split_stack) |
| gold_fatal(_("cannot mix split-stack '%s' and " |
| "non-split-stack '%s' when using -r"), |
| (*input_objects->relobj_begin())->name().c_str(), |
| (*p)->name().c_str()); |
| } |
| } |
| } |
| |
| if (is_debugging_enabled(DEBUG_SCRIPT)) |
| layout->script_options()->print(stderr); |
| |
| // For each dynamic object, record whether we've seen all the |
| // dynamic objects that it depends upon. |
| input_objects->check_dynamic_dependencies(); |
| |
| // See if any of the input definitions violate the One Definition Rule. |
| // TODO: if this is too slow, do this as a task, rather than inline. |
| symtab->detect_odr_violations(task, options.output_file_name()); |
| |
| // Do the --no-undefined-version check. |
| if (!parameters->options().undefined_version()) |
| { |
| Script_options* so = layout->script_options(); |
| so->version_script_info()->check_unmatched_names(symtab); |
| } |
| |
| // Create any automatic note sections. |
| layout->create_notes(); |
| |
| // Create any output sections required by any linker script. |
| layout->create_script_sections(); |
| |
| // Define some sections and symbols needed for a dynamic link. This |
| // handles some cases we want to see before we read the relocs. |
| layout->create_initial_dynamic_sections(symtab); |
| |
| // Define symbols from any linker scripts. |
| layout->define_script_symbols(symtab); |
| |
| // Attach sections to segments. |
| layout->attach_sections_to_segments(); |
| |
| if (!parameters->options().relocatable()) |
| { |
| // Predefine standard symbols. |
| define_standard_symbols(symtab, layout); |
| |
| // Define __start and __stop symbols for output sections where |
| // appropriate. |
| layout->define_section_symbols(symtab); |
| } |
| |
| // Make sure we have symbols for any required group signatures. |
| layout->define_group_signatures(symtab); |
| |
| Task_token* this_blocker = NULL; |
| |
| // Allocate common symbols. We use a blocker to run this before the |
| // Scan_relocs tasks, because it writes to the symbol table just as |
| // they do. |
| if (parameters->options().define_common()) |
| { |
| this_blocker = new Task_token(true); |
| this_blocker->add_blocker(); |
| workqueue->queue(new Allocate_commons_task(symtab, layout, mapfile, |
| this_blocker)); |
| } |
| |
| // If doing garbage collection, the relocations have already been read. |
| // Otherwise, read and scan the relocations. |
| if (parameters->options().gc_sections() |
| || parameters->options().icf_enabled()) |
| { |
| for (Input_objects::Relobj_iterator p = input_objects->relobj_begin(); |
| p != input_objects->relobj_end(); |
| ++p) |
| { |
| Task_token* next_blocker = new Task_token(true); |
| next_blocker->add_blocker(); |
| workqueue->queue(new Scan_relocs(symtab, layout, *p, |
| (*p)->get_relocs_data(), |
| this_blocker, next_blocker)); |
| this_blocker = next_blocker; |
| } |
| } |
| else |
| { |
| // Read the relocations of the input files. We do this to find |
| // which symbols are used by relocations which require a GOT and/or |
| // a PLT entry, or a COPY reloc. When we implement garbage |
| // collection we will do it here by reading the relocations in a |
| // breadth first search by references. |
| // |
| // We could also read the relocations during the first pass, and |
| // mark symbols at that time. That is how the old GNU linker works. |
| // Doing that is more complex, since we may later decide to discard |
| // some of the sections, and thus change our minds about the types |
| // of references made to the symbols. |
| for (Input_objects::Relobj_iterator p = input_objects->relobj_begin(); |
| p != input_objects->relobj_end(); |
| ++p) |
| { |
| Task_token* next_blocker = new Task_token(true); |
| next_blocker->add_blocker(); |
| workqueue->queue(new Read_relocs(symtab, layout, *p, this_blocker, |
| next_blocker)); |
| this_blocker = next_blocker; |
| } |
| } |
| |
| if (this_blocker == NULL) |
| { |
| if (input_objects->number_of_relobjs() == 0) |
| { |
| // If we are given only archives in input, we have no regular |
| // objects and THIS_BLOCKER is NULL here. Create a dummy |
| // blocker here so that we can run the layout task immediately. |
| this_blocker = new Task_token(true); |
| } |
| else |
| { |
| // If we failed to open any input files, it's possible for |
| // THIS_BLOCKER to be NULL here. There's no real point in |
| // continuing if that happens. |
| gold_assert(parameters->errors()->error_count() > 0); |
| gold_exit(false); |
| } |
| } |
| |
| // When all those tasks are complete, we can start laying out the |
| // output file. |
| // TODO(csilvers): figure out a more principled way to get the target |
| Target* target = const_cast<Target*>(¶meters->target()); |
| workqueue->queue(new Task_function(new Layout_task_runner(options, |
| input_objects, |
| symtab, |
| target, |
| layout, |
| mapfile), |
| this_blocker, |
| "Task_function Layout_task_runner")); |
| } |
| |
| // Queue up the final set of tasks. This is called at the end of |
| // Layout_task. |
| |
| void |
| queue_final_tasks(const General_options& options, |
| const Input_objects* input_objects, |
| const Symbol_table* symtab, |
| Layout* layout, |
| Workqueue* workqueue, |
| Output_file* of) |
| { |
| int thread_count = options.thread_count_final(); |
| if (thread_count == 0) |
| thread_count = std::max(2, input_objects->number_of_input_objects()); |
| workqueue->set_thread_count(thread_count); |
| |
| bool any_postprocessing_sections = layout->any_postprocessing_sections(); |
| |
| // Use a blocker to wait until all the input sections have been |
| // written out. |
| Task_token* input_sections_blocker = NULL; |
| if (!any_postprocessing_sections) |
| { |
| input_sections_blocker = new Task_token(true); |
| input_sections_blocker->add_blockers(input_objects->number_of_relobjs()); |
| } |
| |
| // Use a blocker to block any objects which have to wait for the |
| // output sections to complete before they can apply relocations. |
| Task_token* output_sections_blocker = new Task_token(true); |
| output_sections_blocker->add_blocker(); |
| |
| // Use a blocker to block the final cleanup task. |
| Task_token* final_blocker = new Task_token(true); |
| // Write_symbols_task, Write_sections_task, Write_data_task, |
| // Relocate_tasks. |
| final_blocker->add_blockers(3); |
| final_blocker->add_blockers(input_objects->number_of_relobjs()); |
| if (!any_postprocessing_sections) |
| final_blocker->add_blocker(); |
| |
| // Queue a task to write out the symbol table. |
| workqueue->queue(new Write_symbols_task(layout, |
| symtab, |
| input_objects, |
| layout->sympool(), |
| layout->dynpool(), |
| of, |
| final_blocker)); |
| |
| // Queue a task to write out the output sections. |
| workqueue->queue(new Write_sections_task(layout, of, output_sections_blocker, |
| final_blocker)); |
| |
| // Queue a task to write out everything else. |
| workqueue->queue(new Write_data_task(layout, symtab, of, final_blocker)); |
| |
| // Queue a task for each input object to relocate the sections and |
| // write out the local symbols. |
| for (Input_objects::Relobj_iterator p = input_objects->relobj_begin(); |
| p != input_objects->relobj_end(); |
| ++p) |
| workqueue->queue(new Relocate_task(symtab, layout, *p, of, |
| input_sections_blocker, |
| output_sections_blocker, |
| final_blocker)); |
| |
| // Queue a task to write out the output sections which depend on |
| // input sections. If there are any sections which require |
| // postprocessing, then we need to do this last, since it may resize |
| // the output file. |
| if (!any_postprocessing_sections) |
| { |
| Task* t = new Write_after_input_sections_task(layout, of, |
| input_sections_blocker, |
| final_blocker); |
| workqueue->queue(t); |
| } |
| else |
| { |
| Task_token *new_final_blocker = new Task_token(true); |
| new_final_blocker->add_blocker(); |
| Task* t = new Write_after_input_sections_task(layout, of, |
| final_blocker, |
| new_final_blocker); |
| workqueue->queue(t); |
| final_blocker = new_final_blocker; |
| } |
| |
| // Queue a task to close the output file. This will be blocked by |
| // FINAL_BLOCKER. |
| workqueue->queue(new Task_function(new Close_task_runner(&options, layout, |
| of), |
| final_blocker, |
| "Task_function Close_task_runner")); |
| } |
| |
| } // End namespace gold. |