| // common.cc -- handle common symbols for gold |
| |
| // Copyright (C) 2006-2021 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 <algorithm> |
| |
| #include "workqueue.h" |
| #include "mapfile.h" |
| #include "layout.h" |
| #include "output.h" |
| #include "symtab.h" |
| #include "common.h" |
| |
| namespace gold |
| { |
| |
| // Allocate_commons_task methods. |
| |
| // This task allocates the common symbols. We arrange to run it |
| // before anything else which needs to access the symbol table. |
| |
| Task_token* |
| Allocate_commons_task::is_runnable() |
| { |
| return NULL; |
| } |
| |
| // Release a blocker. |
| |
| void |
| Allocate_commons_task::locks(Task_locker* tl) |
| { |
| tl->add(this, this->blocker_); |
| } |
| |
| // Allocate the common symbols. |
| |
| void |
| Allocate_commons_task::run(Workqueue*) |
| { |
| this->symtab_->allocate_commons(this->layout_, this->mapfile_); |
| } |
| |
| // This class is used to sort the common symbol. We normally put the |
| // larger common symbols first. This can be changed by using |
| // --sort-commons, which tells the linker to sort by alignment. |
| |
| template<int size> |
| class Sort_commons |
| { |
| public: |
| Sort_commons(const Symbol_table* symtab, |
| Symbol_table::Sort_commons_order sort_order) |
| : symtab_(symtab), sort_order_(sort_order) |
| { } |
| |
| bool operator()(const Symbol* a, const Symbol* b) const; |
| |
| private: |
| // The symbol table. |
| const Symbol_table* symtab_; |
| // How to sort. |
| Symbol_table::Sort_commons_order sort_order_; |
| }; |
| |
| template<int size> |
| bool |
| Sort_commons<size>::operator()(const Symbol* pa, const Symbol* pb) const |
| { |
| if (pa == NULL) |
| return false; |
| if (pb == NULL) |
| return true; |
| |
| const Symbol_table* symtab = this->symtab_; |
| const Sized_symbol<size>* psa = symtab->get_sized_symbol<size>(pa); |
| const Sized_symbol<size>* psb = symtab->get_sized_symbol<size>(pb); |
| |
| // The size. |
| typename Sized_symbol<size>::Size_type sa = psa->symsize(); |
| typename Sized_symbol<size>::Size_type sb = psb->symsize(); |
| |
| // The alignment. |
| typename Sized_symbol<size>::Value_type aa = psa->value(); |
| typename Sized_symbol<size>::Value_type ab = psb->value(); |
| |
| if (this->sort_order_ == Symbol_table::SORT_COMMONS_BY_ALIGNMENT_DESCENDING) |
| { |
| if (aa < ab) |
| return false; |
| else if (ab < aa) |
| return true; |
| } |
| else if (this->sort_order_ |
| == Symbol_table::SORT_COMMONS_BY_ALIGNMENT_ASCENDING) |
| { |
| if (aa < ab) |
| return true; |
| else if (ab < aa) |
| return false; |
| } |
| else |
| gold_assert(this->sort_order_ |
| == Symbol_table::SORT_COMMONS_BY_SIZE_DESCENDING); |
| |
| // Sort by descending size. |
| if (sa < sb) |
| return false; |
| else if (sb < sa) |
| return true; |
| |
| if (this->sort_order_ == Symbol_table::SORT_COMMONS_BY_SIZE_DESCENDING) |
| { |
| // When the symbols are the same size, we sort them by |
| // alignment, largest alignment first. |
| if (aa < ab) |
| return false; |
| else if (ab < aa) |
| return true; |
| } |
| |
| // Otherwise we stabilize the sort by sorting by name. |
| return strcmp(psa->name(), psb->name()) < 0; |
| } |
| |
| // Allocate the common symbols. |
| |
| void |
| Symbol_table::allocate_commons(Layout* layout, Mapfile* mapfile) |
| { |
| Sort_commons_order sort_order; |
| if (!parameters->options().user_set_sort_common()) |
| sort_order = SORT_COMMONS_BY_SIZE_DESCENDING; |
| else |
| { |
| const char* order = parameters->options().sort_common(); |
| if (*order == '\0' || strcmp(order, "descending") == 0) |
| sort_order = SORT_COMMONS_BY_ALIGNMENT_DESCENDING; |
| else if (strcmp(order, "ascending") == 0) |
| sort_order = SORT_COMMONS_BY_ALIGNMENT_ASCENDING; |
| else |
| { |
| gold_error("invalid --sort-common argument: %s", order); |
| sort_order = SORT_COMMONS_BY_SIZE_DESCENDING; |
| } |
| } |
| |
| if (parameters->target().get_size() == 32) |
| { |
| #if defined(HAVE_TARGET_32_LITTLE) || defined(HAVE_TARGET_32_BIG) |
| this->do_allocate_commons<32>(layout, mapfile, sort_order); |
| #else |
| gold_unreachable(); |
| #endif |
| } |
| else if (parameters->target().get_size() == 64) |
| { |
| #if defined(HAVE_TARGET_64_LITTLE) || defined(HAVE_TARGET_64_BIG) |
| this->do_allocate_commons<64>(layout, mapfile, sort_order); |
| #else |
| gold_unreachable(); |
| #endif |
| } |
| else |
| gold_unreachable(); |
| } |
| |
| // Allocated the common symbols, sized version. |
| |
| template<int size> |
| void |
| Symbol_table::do_allocate_commons(Layout* layout, Mapfile* mapfile, |
| Sort_commons_order sort_order) |
| { |
| if (!this->commons_.empty()) |
| this->do_allocate_commons_list<size>(layout, COMMONS_NORMAL, |
| &this->commons_, mapfile, |
| sort_order); |
| if (!this->tls_commons_.empty()) |
| this->do_allocate_commons_list<size>(layout, COMMONS_TLS, |
| &this->tls_commons_, mapfile, |
| sort_order); |
| if (!this->small_commons_.empty()) |
| this->do_allocate_commons_list<size>(layout, COMMONS_SMALL, |
| &this->small_commons_, mapfile, |
| sort_order); |
| if (!this->large_commons_.empty()) |
| this->do_allocate_commons_list<size>(layout, COMMONS_LARGE, |
| &this->large_commons_, mapfile, |
| sort_order); |
| } |
| |
| // Allocate the common symbols in a list. IS_TLS indicates whether |
| // these are TLS common symbols. |
| |
| template<int size> |
| void |
| Symbol_table::do_allocate_commons_list( |
| Layout* layout, |
| Commons_section_type commons_section_type, |
| Commons_type* commons, |
| Mapfile* mapfile, |
| Sort_commons_order sort_order) |
| { |
| // We've kept a list of all the common symbols. But the symbol may |
| // have been resolved to a defined symbol by now. And it may be a |
| // forwarder. First remove all non-common symbols. |
| bool any = false; |
| uint64_t addralign = 0; |
| for (Commons_type::iterator p = commons->begin(); |
| p != commons->end(); |
| ++p) |
| { |
| Symbol* sym = *p; |
| if (sym->is_forwarder()) |
| { |
| sym = this->resolve_forwards(sym); |
| *p = sym; |
| } |
| if (!sym->is_common()) |
| *p = NULL; |
| else |
| { |
| any = true; |
| Sized_symbol<size>* ssym = this->get_sized_symbol<size>(sym); |
| if (ssym->value() > addralign) |
| addralign = ssym->value(); |
| } |
| } |
| if (!any) |
| return; |
| |
| // Sort the common symbols. |
| std::sort(commons->begin(), commons->end(), |
| Sort_commons<size>(this, sort_order)); |
| |
| // Place them in a newly allocated BSS section. |
| elfcpp::Elf_Xword flags = elfcpp::SHF_WRITE | elfcpp::SHF_ALLOC; |
| const char* name; |
| const char* ds_name; |
| switch (commons_section_type) |
| { |
| case COMMONS_NORMAL: |
| name = ".bss"; |
| ds_name = "** common"; |
| break; |
| case COMMONS_TLS: |
| flags |= elfcpp::SHF_TLS; |
| name = ".tbss"; |
| ds_name = "** tls common"; |
| break; |
| case COMMONS_SMALL: |
| flags |= parameters->target().small_common_section_flags(); |
| name = ".sbss"; |
| ds_name = "** small common"; |
| break; |
| case COMMONS_LARGE: |
| flags |= parameters->target().large_common_section_flags(); |
| name = ".lbss"; |
| ds_name = "** large common"; |
| break; |
| default: |
| gold_unreachable(); |
| } |
| |
| Output_data_space* poc; |
| Output_section* os; |
| |
| if (!parameters->incremental_update()) |
| { |
| poc = new Output_data_space(addralign, ds_name); |
| os = layout->add_output_section_data(name, elfcpp::SHT_NOBITS, flags, |
| poc, ORDER_INVALID, false); |
| } |
| else |
| { |
| // When doing an incremental update, we need to allocate each common |
| // directly from the output section's free list. |
| poc = NULL; |
| os = layout->find_output_section(name); |
| } |
| |
| if (os != NULL) |
| { |
| if (commons_section_type == COMMONS_SMALL) |
| os->set_is_small_section(); |
| else if (commons_section_type == COMMONS_LARGE) |
| os->set_is_large_section(); |
| } |
| |
| // Allocate them all. |
| |
| off_t off = 0; |
| for (Commons_type::iterator p = commons->begin(); |
| p != commons->end(); |
| ++p) |
| { |
| Symbol* sym = *p; |
| if (sym == NULL) |
| break; |
| |
| // Because we followed forwarding symbols above, but we didn't |
| // do it reliably before adding symbols to the list, it is |
| // possible for us to have the same symbol on the list twice. |
| // This can happen in the horrible case where a program defines |
| // a common symbol with the same name as a versioned libc |
| // symbol. That will show up here as a symbol which has already |
| // been allocated and is therefore no longer a common symbol. |
| if (!sym->is_common()) |
| continue; |
| |
| Sized_symbol<size>* ssym = this->get_sized_symbol<size>(sym); |
| |
| // Record the symbol in the map file now, before we change its |
| // value. Pass the size in separately so that we don't have to |
| // templatize the map code, which is not performance sensitive. |
| if (mapfile != NULL) |
| mapfile->report_allocate_common(sym, ssym->symsize()); |
| |
| if (poc != NULL) |
| { |
| off = align_address(off, ssym->value()); |
| ssym->allocate_common(poc, off); |
| off += ssym->symsize(); |
| } |
| else |
| { |
| // For an incremental update, allocate from the free list. |
| off = os->allocate(ssym->symsize(), ssym->value()); |
| if (off == -1) |
| gold_fallback(_("out of patch space in section %s; " |
| "relink with --incremental-full"), |
| os->name()); |
| ssym->allocate_common(os, off); |
| } |
| } |
| |
| if (poc != NULL) |
| poc->set_current_data_size(off); |
| |
| commons->clear(); |
| } |
| |
| } // End namespace gold. |