// script-sections.cc -- linker script SECTIONS for gold // Copyright 2008, 2009 Free Software Foundation, Inc. // Written by Ian Lance Taylor . // 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 #include #include #include #include #include #include #include "parameters.h" #include "object.h" #include "layout.h" #include "output.h" #include "script-c.h" #include "script.h" #include "script-sections.h" // Support for the SECTIONS clause in linker scripts. namespace gold { // Manage orphan sections. This is intended to be largely compatible // with the GNU linker. The Linux kernel implicitly relies on // something similar to the GNU linker's orphan placement. We // originally used a simpler scheme here, but it caused the kernel // build to fail, and was also rather inefficient. class Orphan_section_placement { private: typedef Script_sections::Elements_iterator Elements_iterator; public: Orphan_section_placement(); // Handle an output section during initialization of this mapping. void output_section_init(const std::string& name, Output_section*, Elements_iterator location); // Initialize the last location. void last_init(Elements_iterator location); // Set *PWHERE to the address of an iterator pointing to the // location to use for an orphan section. Return true if the // iterator has a value, false otherwise. bool find_place(Output_section*, Elements_iterator** pwhere); // Return the iterator being used for sections at the very end of // the linker script. Elements_iterator last_place() const; private: // The places that we specifically recognize. This list is copied // from the GNU linker. enum Place_index { PLACE_TEXT, PLACE_RODATA, PLACE_DATA, PLACE_TLS, PLACE_TLS_BSS, PLACE_BSS, PLACE_REL, PLACE_INTERP, PLACE_NONALLOC, PLACE_LAST, PLACE_MAX }; // The information we keep for a specific place. struct Place { // The name of sections for this place. const char* name; // Whether we have a location for this place. bool have_location; // The iterator for this place. Elements_iterator location; }; // Initialize one place element. void initialize_place(Place_index, const char*); // The places. Place places_[PLACE_MAX]; // True if this is the first call to output_section_init. bool first_init_; }; // Initialize Orphan_section_placement. Orphan_section_placement::Orphan_section_placement() : first_init_(true) { this->initialize_place(PLACE_TEXT, ".text"); this->initialize_place(PLACE_RODATA, ".rodata"); this->initialize_place(PLACE_DATA, ".data"); this->initialize_place(PLACE_TLS, NULL); this->initialize_place(PLACE_TLS_BSS, NULL); this->initialize_place(PLACE_BSS, ".bss"); this->initialize_place(PLACE_REL, NULL); this->initialize_place(PLACE_INTERP, ".interp"); this->initialize_place(PLACE_NONALLOC, NULL); this->initialize_place(PLACE_LAST, NULL); } // Initialize one place element. void Orphan_section_placement::initialize_place(Place_index index, const char* name) { this->places_[index].name = name; this->places_[index].have_location = false; } // While initializing the Orphan_section_placement information, this // is called once for each output section named in the linker script. // If we found an output section during the link, it will be passed in // OS. void Orphan_section_placement::output_section_init(const std::string& name, Output_section* os, Elements_iterator location) { bool first_init = this->first_init_; this->first_init_ = false; for (int i = 0; i < PLACE_MAX; ++i) { if (this->places_[i].name != NULL && this->places_[i].name == name) { if (this->places_[i].have_location) { // We have already seen a section with this name. return; } this->places_[i].location = location; this->places_[i].have_location = true; // If we just found the .bss section, restart the search for // an unallocated section. This follows the GNU linker's // behaviour. if (i == PLACE_BSS) this->places_[PLACE_NONALLOC].have_location = false; return; } } // Relocation sections. if (!this->places_[PLACE_REL].have_location && os != NULL && (os->type() == elfcpp::SHT_REL || os->type() == elfcpp::SHT_RELA) && (os->flags() & elfcpp::SHF_ALLOC) != 0) { this->places_[PLACE_REL].location = location; this->places_[PLACE_REL].have_location = true; } // We find the location for unallocated sections by finding the // first debugging or comment section after the BSS section (if // there is one). if (!this->places_[PLACE_NONALLOC].have_location && (name == ".comment" || Layout::is_debug_info_section(name.c_str()))) { // We add orphan sections after the location in PLACES_. We // want to store unallocated sections before LOCATION. If this // is the very first section, we can't use it. if (!first_init) { --location; this->places_[PLACE_NONALLOC].location = location; this->places_[PLACE_NONALLOC].have_location = true; } } } // Initialize the last location. void Orphan_section_placement::last_init(Elements_iterator location) { this->places_[PLACE_LAST].location = location; this->places_[PLACE_LAST].have_location = true; } // Set *PWHERE to the address of an iterator pointing to the location // to use for an orphan section. Return true if the iterator has a // value, false otherwise. bool Orphan_section_placement::find_place(Output_section* os, Elements_iterator** pwhere) { // Figure out where OS should go. This is based on the GNU linker // code. FIXME: The GNU linker handles small data sections // specially, but we don't. elfcpp::Elf_Word type = os->type(); elfcpp::Elf_Xword flags = os->flags(); Place_index index; if ((flags & elfcpp::SHF_ALLOC) == 0 && !Layout::is_debug_info_section(os->name())) index = PLACE_NONALLOC; else if ((flags & elfcpp::SHF_ALLOC) == 0) index = PLACE_LAST; else if (type == elfcpp::SHT_NOTE) index = PLACE_INTERP; else if ((flags & elfcpp::SHF_TLS) != 0) { if (type == elfcpp::SHT_NOBITS) index = PLACE_TLS_BSS; else index = PLACE_TLS; } else if (type == elfcpp::SHT_NOBITS) index = PLACE_BSS; else if ((flags & elfcpp::SHF_WRITE) != 0) index = PLACE_DATA; else if (type == elfcpp::SHT_REL || type == elfcpp::SHT_RELA) index = PLACE_REL; else if ((flags & elfcpp::SHF_EXECINSTR) == 0) index = PLACE_RODATA; else index = PLACE_TEXT; // If we don't have a location yet, try to find one based on a // plausible ordering of sections. if (!this->places_[index].have_location) { Place_index follow; switch (index) { default: follow = PLACE_MAX; break; case PLACE_RODATA: follow = PLACE_TEXT; break; case PLACE_BSS: follow = PLACE_DATA; break; case PLACE_REL: follow = PLACE_TEXT; break; case PLACE_INTERP: follow = PLACE_TEXT; break; case PLACE_TLS: follow = PLACE_DATA; break; case PLACE_TLS_BSS: follow = PLACE_TLS; if (!this->places_[PLACE_TLS].have_location) follow = PLACE_DATA; break; } if (follow != PLACE_MAX && this->places_[follow].have_location) { // Set the location of INDEX to the location of FOLLOW. The // location of INDEX will then be incremented by the caller, // so anything in INDEX will continue to be after anything // in FOLLOW. this->places_[index].location = this->places_[follow].location; this->places_[index].have_location = true; } } *pwhere = &this->places_[index].location; bool ret = this->places_[index].have_location; // The caller will set the location. this->places_[index].have_location = true; return ret; } // Return the iterator being used for sections at the very end of the // linker script. Orphan_section_placement::Elements_iterator Orphan_section_placement::last_place() const { gold_assert(this->places_[PLACE_LAST].have_location); return this->places_[PLACE_LAST].location; } // An element in a SECTIONS clause. class Sections_element { public: Sections_element() { } virtual ~Sections_element() { } // Return whether an output section is relro. virtual bool is_relro() const { return false; } // Record that an output section is relro. virtual void set_is_relro() { } // Create any required output sections. The only real // implementation is in Output_section_definition. virtual void create_sections(Layout*) { } // Add any symbol being defined to the symbol table. virtual void add_symbols_to_table(Symbol_table*) { } // Finalize symbols and check assertions. virtual void finalize_symbols(Symbol_table*, const Layout*, uint64_t*) { } // Return the output section name to use for an input file name and // section name. This only real implementation is in // Output_section_definition. virtual const char* output_section_name(const char*, const char*, Output_section***, Script_sections::Section_type*) { return NULL; } // Initialize OSP with an output section. virtual void orphan_section_init(Orphan_section_placement*, Script_sections::Elements_iterator) { } // Set section addresses. This includes applying assignments if the // the expression is an absolute value. virtual void set_section_addresses(Symbol_table*, Layout*, uint64_t*, uint64_t*, uint64_t*) { } // Check a constraint (ONLY_IF_RO, etc.) on an output section. If // this section is constrained, and the input sections do not match, // return the constraint, and set *POSD. virtual Section_constraint check_constraint(Output_section_definition**) { return CONSTRAINT_NONE; } // See if this is the alternate output section for a constrained // output section. If it is, transfer the Output_section and return // true. Otherwise return false. virtual bool alternate_constraint(Output_section_definition*, Section_constraint) { return false; } // Get the list of segments to use for an allocated section when // using a PHDRS clause. If this is an allocated section, return // the Output_section, and set *PHDRS_LIST (the first parameter) to // the list of PHDRS to which it should be attached. If the PHDRS // were not specified, don't change *PHDRS_LIST. When not returning // NULL, set *ORPHAN (the second parameter) according to whether // this is an orphan section--one that is not mentioned in the // linker script. virtual Output_section* allocate_to_segment(String_list**, bool*) { return NULL; } // Look for an output section by name and return the address, the // load address, the alignment, and the size. This is used when an // expression refers to an output section which was not actually // created. This returns true if the section was found, false // otherwise. The only real definition is for // Output_section_definition. virtual bool get_output_section_info(const char*, uint64_t*, uint64_t*, uint64_t*, uint64_t*) const { return false; } // Return the associated Output_section if there is one. virtual Output_section* get_output_section() const { return NULL; } // Print the element for debugging purposes. virtual void print(FILE* f) const = 0; }; // An assignment in a SECTIONS clause outside of an output section. class Sections_element_assignment : public Sections_element { public: Sections_element_assignment(const char* name, size_t namelen, Expression* val, bool provide, bool hidden) : assignment_(name, namelen, false, val, provide, hidden) { } // Add the symbol to the symbol table. void add_symbols_to_table(Symbol_table* symtab) { this->assignment_.add_to_table(symtab); } // Finalize the symbol. void finalize_symbols(Symbol_table* symtab, const Layout* layout, uint64_t* dot_value) { this->assignment_.finalize_with_dot(symtab, layout, *dot_value, NULL); } // Set the section address. There is no section here, but if the // value is absolute, we set the symbol. This permits us to use // absolute symbols when setting dot. void set_section_addresses(Symbol_table* symtab, Layout* layout, uint64_t* dot_value, uint64_t*, uint64_t*) { this->assignment_.set_if_absolute(symtab, layout, true, *dot_value); } // Print for debugging. void print(FILE* f) const { fprintf(f, " "); this->assignment_.print(f); } private: Symbol_assignment assignment_; }; // An assignment to the dot symbol in a SECTIONS clause outside of an // output section. class Sections_element_dot_assignment : public Sections_element { public: Sections_element_dot_assignment(Expression* val) : val_(val) { } // Finalize the symbol. void finalize_symbols(Symbol_table* symtab, const Layout* layout, uint64_t* dot_value) { // We ignore the section of the result because outside of an // output section definition the dot symbol is always considered // to be absolute. Output_section* dummy; *dot_value = this->val_->eval_with_dot(symtab, layout, true, *dot_value, NULL, &dummy, NULL); } // Update the dot symbol while setting section addresses. void set_section_addresses(Symbol_table* symtab, Layout* layout, uint64_t* dot_value, uint64_t* dot_alignment, uint64_t* load_address) { Output_section* dummy; *dot_value = this->val_->eval_with_dot(symtab, layout, false, *dot_value, NULL, &dummy, dot_alignment); *load_address = *dot_value; } // Print for debugging. void print(FILE* f) const { fprintf(f, " . = "); this->val_->print(f); fprintf(f, "\n"); } private: Expression* val_; }; // An assertion in a SECTIONS clause outside of an output section. class Sections_element_assertion : public Sections_element { public: Sections_element_assertion(Expression* check, const char* message, size_t messagelen) : assertion_(check, message, messagelen) { } // Check the assertion. void finalize_symbols(Symbol_table* symtab, const Layout* layout, uint64_t*) { this->assertion_.check(symtab, layout); } // Print for debugging. void print(FILE* f) const { fprintf(f, " "); this->assertion_.print(f); } private: Script_assertion assertion_; }; // An element in an output section in a SECTIONS clause. class Output_section_element { public: // A list of input sections. typedef std::list Input_section_list; Output_section_element() { } virtual ~Output_section_element() { } // Return whether this element requires an output section to exist. virtual bool needs_output_section() const { return false; } // Add any symbol being defined to the symbol table. virtual void add_symbols_to_table(Symbol_table*) { } // Finalize symbols and check assertions. virtual void finalize_symbols(Symbol_table*, const Layout*, uint64_t*, Output_section**) { } // Return whether this element matches FILE_NAME and SECTION_NAME. // The only real implementation is in Output_section_element_input. virtual bool match_name(const char*, const char*) const { return false; } // Set section addresses. This includes applying assignments if the // the expression is an absolute value. virtual void set_section_addresses(Symbol_table*, Layout*, Output_section*, uint64_t, uint64_t*, uint64_t*, Output_section**, std::string*, Input_section_list*) { } // Print the element for debugging purposes. virtual void print(FILE* f) const = 0; protected: // Return a fill string that is LENGTH bytes long, filling it with // FILL. std::string get_fill_string(const std::string* fill, section_size_type length) const; }; std::string Output_section_element::get_fill_string(const std::string* fill, section_size_type length) const { std::string this_fill; this_fill.reserve(length); while (this_fill.length() + fill->length() <= length) this_fill += *fill; if (this_fill.length() < length) this_fill.append(*fill, 0, length - this_fill.length()); return this_fill; } // A symbol assignment in an output section. class Output_section_element_assignment : public Output_section_element { public: Output_section_element_assignment(const char* name, size_t namelen, Expression* val, bool provide, bool hidden) : assignment_(name, namelen, false, val, provide, hidden) { } // Add the symbol to the symbol table. void add_symbols_to_table(Symbol_table* symtab) { this->assignment_.add_to_table(symtab); } // Finalize the symbol. void finalize_symbols(Symbol_table* symtab, const Layout* layout, uint64_t* dot_value, Output_section** dot_section) { this->assignment_.finalize_with_dot(symtab, layout, *dot_value, *dot_section); } // Set the section address. There is no section here, but if the // value is absolute, we set the symbol. This permits us to use // absolute symbols when setting dot. void set_section_addresses(Symbol_table* symtab, Layout* layout, Output_section*, uint64_t, uint64_t* dot_value, uint64_t*, Output_section**, std::string*, Input_section_list*) { this->assignment_.set_if_absolute(symtab, layout, true, *dot_value); } // Print for debugging. void print(FILE* f) const { fprintf(f, " "); this->assignment_.print(f); } private: Symbol_assignment assignment_; }; // An assignment to the dot symbol in an output section. class Output_section_element_dot_assignment : public Output_section_element { public: Output_section_element_dot_assignment(Expression* val) : val_(val) { } // Finalize the symbol. void finalize_symbols(Symbol_table* symtab, const Layout* layout, uint64_t* dot_value, Output_section** dot_section) { *dot_value = this->val_->eval_with_dot(symtab, layout, true, *dot_value, *dot_section, dot_section, NULL); } // Update the dot symbol while setting section addresses. void set_section_addresses(Symbol_table* symtab, Layout* layout, Output_section*, uint64_t, uint64_t* dot_value, uint64_t*, Output_section**, std::string*, Input_section_list*); // Print for debugging. void print(FILE* f) const { fprintf(f, " . = "); this->val_->print(f); fprintf(f, "\n"); } private: Expression* val_; }; // Update the dot symbol while setting section addresses. void Output_section_element_dot_assignment::set_section_addresses( Symbol_table* symtab, Layout* layout, Output_section* output_section, uint64_t, uint64_t* dot_value, uint64_t* dot_alignment, Output_section** dot_section, std::string* fill, Input_section_list*) { uint64_t next_dot = this->val_->eval_with_dot(symtab, layout, false, *dot_value, *dot_section, dot_section, dot_alignment); if (next_dot < *dot_value) gold_error(_("dot may not move backward")); if (next_dot > *dot_value && output_section != NULL) { section_size_type length = convert_to_section_size_type(next_dot - *dot_value); Output_section_data* posd; if (fill->empty()) posd = new Output_data_zero_fill(length, 0); else { std::string this_fill = this->get_fill_string(fill, length); posd = new Output_data_const(this_fill, 0); } output_section->add_output_section_data(posd); layout->new_output_section_data_from_script(posd); } *dot_value = next_dot; } // An assertion in an output section. class Output_section_element_assertion : public Output_section_element { public: Output_section_element_assertion(Expression* check, const char* message, size_t messagelen) : assertion_(check, message, messagelen) { } void print(FILE* f) const { fprintf(f, " "); this->assertion_.print(f); } private: Script_assertion assertion_; }; // We use a special instance of Output_section_data to handle BYTE, // SHORT, etc. This permits forward references to symbols in the // expressions. class Output_data_expression : public Output_section_data { public: Output_data_expression(int size, bool is_signed, Expression* val, const Symbol_table* symtab, const Layout* layout, uint64_t dot_value, Output_section* dot_section) : Output_section_data(size, 0, true), is_signed_(is_signed), val_(val), symtab_(symtab), layout_(layout), dot_value_(dot_value), dot_section_(dot_section) { } protected: // Write the data to the output file. void do_write(Output_file*); // Write the data to a buffer. void do_write_to_buffer(unsigned char*); // Write to a map file. void do_print_to_mapfile(Mapfile* mapfile) const { mapfile->print_output_data(this, _("** expression")); } private: template void endian_write_to_buffer(uint64_t, unsigned char*); bool is_signed_; Expression* val_; const Symbol_table* symtab_; const Layout* layout_; uint64_t dot_value_; Output_section* dot_section_; }; // Write the data element to the output file. void Output_data_expression::do_write(Output_file* of) { unsigned char* view = of->get_output_view(this->offset(), this->data_size()); this->write_to_buffer(view); of->write_output_view(this->offset(), this->data_size(), view); } // Write the data element to a buffer. void Output_data_expression::do_write_to_buffer(unsigned char* buf) { Output_section* dummy; uint64_t val = this->val_->eval_with_dot(this->symtab_, this->layout_, true, this->dot_value_, this->dot_section_, &dummy, NULL); if (parameters->target().is_big_endian()) this->endian_write_to_buffer(val, buf); else this->endian_write_to_buffer(val, buf); } template void Output_data_expression::endian_write_to_buffer(uint64_t val, unsigned char* buf) { switch (this->data_size()) { case 1: elfcpp::Swap_unaligned<8, big_endian>::writeval(buf, val); break; case 2: elfcpp::Swap_unaligned<16, big_endian>::writeval(buf, val); break; case 4: elfcpp::Swap_unaligned<32, big_endian>::writeval(buf, val); break; case 8: if (parameters->target().get_size() == 32) { val &= 0xffffffff; if (this->is_signed_ && (val & 0x80000000) != 0) val |= 0xffffffff00000000LL; } elfcpp::Swap_unaligned<64, big_endian>::writeval(buf, val); break; default: gold_unreachable(); } } // A data item in an output section. class Output_section_element_data : public Output_section_element { public: Output_section_element_data(int size, bool is_signed, Expression* val) : size_(size), is_signed_(is_signed), val_(val) { } // If there is a data item, then we must create an output section. bool needs_output_section() const { return true; } // Finalize symbols--we just need to update dot. void finalize_symbols(Symbol_table*, const Layout*, uint64_t* dot_value, Output_section**) { *dot_value += this->size_; } // Store the value in the section. void set_section_addresses(Symbol_table*, Layout*, Output_section*, uint64_t, uint64_t* dot_value, uint64_t*, Output_section**, std::string*, Input_section_list*); // Print for debugging. void print(FILE*) const; private: // The size in bytes. int size_; // Whether the value is signed. bool is_signed_; // The value. Expression* val_; }; // Store the value in the section. void Output_section_element_data::set_section_addresses( Symbol_table* symtab, Layout* layout, Output_section* os, uint64_t, uint64_t* dot_value, uint64_t*, Output_section** dot_section, std::string*, Input_section_list*) { gold_assert(os != NULL); Output_data_expression* expression = new Output_data_expression(this->size_, this->is_signed_, this->val_, symtab, layout, *dot_value, *dot_section); os->add_output_section_data(expression); layout->new_output_section_data_from_script(expression); *dot_value += this->size_; } // Print for debugging. void Output_section_element_data::print(FILE* f) const { const char* s; switch (this->size_) { case 1: s = "BYTE"; break; case 2: s = "SHORT"; break; case 4: s = "LONG"; break; case 8: if (this->is_signed_) s = "SQUAD"; else s = "QUAD"; break; default: gold_unreachable(); } fprintf(f, " %s(", s); this->val_->print(f); fprintf(f, ")\n"); } // A fill value setting in an output section. class Output_section_element_fill : public Output_section_element { public: Output_section_element_fill(Expression* val) : val_(val) { } // Update the fill value while setting section addresses. void set_section_addresses(Symbol_table* symtab, Layout* layout, Output_section*, uint64_t, uint64_t* dot_value, uint64_t*, Output_section** dot_section, std::string* fill, Input_section_list*) { Output_section* fill_section; uint64_t fill_val = this->val_->eval_with_dot(symtab, layout, false, *dot_value, *dot_section, &fill_section, NULL); if (fill_section != NULL) gold_warning(_("fill value is not absolute")); // FIXME: The GNU linker supports fill values of arbitrary length. unsigned char fill_buff[4]; elfcpp::Swap_unaligned<32, true>::writeval(fill_buff, fill_val); fill->assign(reinterpret_cast(fill_buff), 4); } // Print for debugging. void print(FILE* f) const { fprintf(f, " FILL("); this->val_->print(f); fprintf(f, ")\n"); } private: // The new fill value. Expression* val_; }; // Return whether STRING contains a wildcard character. This is used // to speed up matching. static inline bool is_wildcard_string(const std::string& s) { return strpbrk(s.c_str(), "?*[") != NULL; } // An input section specification in an output section class Output_section_element_input : public Output_section_element { public: Output_section_element_input(const Input_section_spec* spec, bool keep); // Finalize symbols--just update the value of the dot symbol. void finalize_symbols(Symbol_table*, const Layout*, uint64_t* dot_value, Output_section** dot_section) { *dot_value = this->final_dot_value_; *dot_section = this->final_dot_section_; } // See whether we match FILE_NAME and SECTION_NAME as an input // section. bool match_name(const char* file_name, const char* section_name) const; // Set the section address. void set_section_addresses(Symbol_table* symtab, Layout* layout, Output_section*, uint64_t subalign, uint64_t* dot_value, uint64_t*, Output_section**, std::string* fill, Input_section_list*); // Print for debugging. void print(FILE* f) const; private: // An input section pattern. struct Input_section_pattern { std::string pattern; bool pattern_is_wildcard; Sort_wildcard sort; Input_section_pattern(const char* patterna, size_t patternlena, Sort_wildcard sorta) : pattern(patterna, patternlena), pattern_is_wildcard(is_wildcard_string(this->pattern)), sort(sorta) { } }; typedef std::vector Input_section_patterns; // Filename_exclusions is a pair of filename pattern and a bool // indicating whether the filename is a wildcard. typedef std::vector > Filename_exclusions; // Return whether STRING matches PATTERN, where IS_WILDCARD_PATTERN // indicates whether this is a wildcard pattern. static inline bool match(const char* string, const char* pattern, bool is_wildcard_pattern) { return (is_wildcard_pattern ? fnmatch(pattern, string, 0) == 0 : strcmp(string, pattern) == 0); } // See if we match a file name. bool match_file_name(const char* file_name) const; // The file name pattern. If this is the empty string, we match all // files. std::string filename_pattern_; // Whether the file name pattern is a wildcard. bool filename_is_wildcard_; // How the file names should be sorted. This may only be // SORT_WILDCARD_NONE or SORT_WILDCARD_BY_NAME. Sort_wildcard filename_sort_; // The list of file names to exclude. Filename_exclusions filename_exclusions_; // The list of input section patterns. Input_section_patterns input_section_patterns_; // Whether to keep this section when garbage collecting. bool keep_; // The value of dot after including all matching sections. uint64_t final_dot_value_; // The section where dot is defined after including all matching // sections. Output_section* final_dot_section_; }; // Construct Output_section_element_input. The parser records strings // as pointers into a copy of the script file, which will go away when // parsing is complete. We make sure they are in std::string objects. Output_section_element_input::Output_section_element_input( const Input_section_spec* spec, bool keep) : filename_pattern_(), filename_is_wildcard_(false), filename_sort_(spec->file.sort), filename_exclusions_(), input_section_patterns_(), keep_(keep), final_dot_value_(0), final_dot_section_(NULL) { // The filename pattern "*" is common, and matches all files. Turn // it into the empty string. if (spec->file.name.length != 1 || spec->file.name.value[0] != '*') this->filename_pattern_.assign(spec->file.name.value, spec->file.name.length); this->filename_is_wildcard_ = is_wildcard_string(this->filename_pattern_); if (spec->input_sections.exclude != NULL) { for (String_list::const_iterator p = spec->input_sections.exclude->begin(); p != spec->input_sections.exclude->end(); ++p) { bool is_wildcard = is_wildcard_string(*p); this->filename_exclusions_.push_back(std::make_pair(*p, is_wildcard)); } } if (spec->input_sections.sections != NULL) { Input_section_patterns& isp(this->input_section_patterns_); for (String_sort_list::const_iterator p = spec->input_sections.sections->begin(); p != spec->input_sections.sections->end(); ++p) isp.push_back(Input_section_pattern(p->name.value, p->name.length, p->sort)); } } // See whether we match FILE_NAME. bool Output_section_element_input::match_file_name(const char* file_name) const { if (!this->filename_pattern_.empty()) { // If we were called with no filename, we refuse to match a // pattern which requires a file name. if (file_name == NULL) return false; if (!match(file_name, this->filename_pattern_.c_str(), this->filename_is_wildcard_)) return false; } if (file_name != NULL) { // Now we have to see whether FILE_NAME matches one of the // exclusion patterns, if any. for (Filename_exclusions::const_iterator p = this->filename_exclusions_.begin(); p != this->filename_exclusions_.end(); ++p) { if (match(file_name, p->first.c_str(), p->second)) return false; } } return true; } // See whether we match FILE_NAME and SECTION_NAME. bool Output_section_element_input::match_name(const char* file_name, const char* section_name) const { if (!this->match_file_name(file_name)) return false; // If there are no section name patterns, then we match. if (this->input_section_patterns_.empty()) return true; // See whether we match the section name patterns. for (Input_section_patterns::const_iterator p = this->input_section_patterns_.begin(); p != this->input_section_patterns_.end(); ++p) { if (match(section_name, p->pattern.c_str(), p->pattern_is_wildcard)) return true; } // We didn't match any section names, so we didn't match. return false; } // Information we use to sort the input sections. class Input_section_info { public: Input_section_info(const Output_section::Input_section& input_section) : input_section_(input_section), section_name_(), size_(0), addralign_(1) { } // Return the simple input section. const Output_section::Input_section& input_section() const { return this->input_section_; } // Return the object. Relobj* relobj() const { return this->input_section_.relobj(); } // Return the section index. unsigned int shndx() { return this->input_section_.shndx(); } // Return the section name. const std::string& section_name() const { return this->section_name_; } // Set the section name. void set_section_name(const std::string name) { this->section_name_ = name; } // Return the section size. uint64_t size() const { return this->size_; } // Set the section size. void set_size(uint64_t size) { this->size_ = size; } // Return the address alignment. uint64_t addralign() const { return this->addralign_; } // Set the address alignment. void set_addralign(uint64_t addralign) { this->addralign_ = addralign; } private: // Input section, can be a relaxed section. Output_section::Input_section input_section_; // Name of the section. std::string section_name_; // Section size. uint64_t size_; // Address alignment. uint64_t addralign_; }; // A class to sort the input sections. class Input_section_sorter { public: Input_section_sorter(Sort_wildcard filename_sort, Sort_wildcard section_sort) : filename_sort_(filename_sort), section_sort_(section_sort) { } bool operator()(const Input_section_info&, const Input_section_info&) const; private: Sort_wildcard filename_sort_; Sort_wildcard section_sort_; }; bool Input_section_sorter::operator()(const Input_section_info& isi1, const Input_section_info& isi2) const { if (this->section_sort_ == SORT_WILDCARD_BY_NAME || this->section_sort_ == SORT_WILDCARD_BY_NAME_BY_ALIGNMENT || (this->section_sort_ == SORT_WILDCARD_BY_ALIGNMENT_BY_NAME && isi1.addralign() == isi2.addralign())) { if (isi1.section_name() != isi2.section_name()) return isi1.section_name() < isi2.section_name(); } if (this->section_sort_ == SORT_WILDCARD_BY_ALIGNMENT || this->section_sort_ == SORT_WILDCARD_BY_NAME_BY_ALIGNMENT || this->section_sort_ == SORT_WILDCARD_BY_ALIGNMENT_BY_NAME) { if (isi1.addralign() != isi2.addralign()) return isi1.addralign() < isi2.addralign(); } if (this->filename_sort_ == SORT_WILDCARD_BY_NAME) { if (isi1.relobj()->name() != isi2.relobj()->name()) return (isi1.relobj()->name() < isi2.relobj()->name()); } // Otherwise we leave them in the same order. return false; } // Set the section address. Look in INPUT_SECTIONS for sections which // match this spec, sort them as specified, and add them to the output // section. void Output_section_element_input::set_section_addresses( Symbol_table*, Layout* layout, Output_section* output_section, uint64_t subalign, uint64_t* dot_value, uint64_t*, Output_section** dot_section, std::string* fill, Input_section_list* input_sections) { // We build a list of sections which match each // Input_section_pattern. typedef std::vector > Matching_sections; size_t input_pattern_count = this->input_section_patterns_.size(); if (input_pattern_count == 0) input_pattern_count = 1; Matching_sections matching_sections(input_pattern_count); // Look through the list of sections for this output section. Add // each one which matches to one of the elements of // MATCHING_SECTIONS. Input_section_list::iterator p = input_sections->begin(); while (p != input_sections->end()) { Relobj* relobj = p->relobj(); unsigned int shndx = p->shndx(); Input_section_info isi(*p); // Calling section_name and section_addralign is not very // efficient. // Lock the object so that we can get information about the // section. This is OK since we know we are single-threaded // here. { const Task* task = reinterpret_cast(-1); Task_lock_obj tl(task, relobj); isi.set_section_name(relobj->section_name(shndx)); if (p->is_relaxed_input_section()) { // We use current data size because relxed section sizes may not // have finalized yet. isi.set_size(p->relaxed_input_section()->current_data_size()); isi.set_addralign(p->relaxed_input_section()->addralign()); } else { isi.set_size(relobj->section_size(shndx)); isi.set_addralign(relobj->section_addralign(shndx)); } } if (!this->match_file_name(relobj->name().c_str())) ++p; else if (this->input_section_patterns_.empty()) { matching_sections[0].push_back(isi); p = input_sections->erase(p); } else { size_t i; for (i = 0; i < input_pattern_count; ++i) { const Input_section_pattern& isp(this->input_section_patterns_[i]); if (match(isi.section_name().c_str(), isp.pattern.c_str(), isp.pattern_is_wildcard)) break; } if (i >= this->input_section_patterns_.size()) ++p; else { matching_sections[i].push_back(isi); p = input_sections->erase(p); } } } // Look through MATCHING_SECTIONS. Sort each one as specified, // using a stable sort so that we get the default order when // sections are otherwise equal. Add each input section to the // output section. uint64_t dot = *dot_value; for (size_t i = 0; i < input_pattern_count; ++i) { if (matching_sections[i].empty()) continue; gold_assert(output_section != NULL); const Input_section_pattern& isp(this->input_section_patterns_[i]); if (isp.sort != SORT_WILDCARD_NONE || this->filename_sort_ != SORT_WILDCARD_NONE) std::stable_sort(matching_sections[i].begin(), matching_sections[i].end(), Input_section_sorter(this->filename_sort_, isp.sort)); for (std::vector::const_iterator p = matching_sections[i].begin(); p != matching_sections[i].end(); ++p) { // Override the original address alignment if SUBALIGN is specified // and is greater than the original alignment. We need to make a // copy of the input section to modify the alignment. Output_section::Input_section sis(p->input_section()); uint64_t this_subalign = sis.addralign(); if (!sis.is_input_section()) sis.output_section_data()->finalize_data_size(); uint64_t data_size = sis.data_size(); if (this_subalign < subalign) { this_subalign = subalign; sis.set_addralign(subalign); } uint64_t address = align_address(dot, this_subalign); if (address > dot && !fill->empty()) { section_size_type length = convert_to_section_size_type(address - dot); std::string this_fill = this->get_fill_string(fill, length); Output_section_data* posd = new Output_data_const(this_fill, 0); output_section->add_output_section_data(posd); layout->new_output_section_data_from_script(posd); } output_section->add_script_input_section(sis); dot = address + data_size; } } // An SHF_TLS/SHT_NOBITS section does not take up any // address space. if (output_section == NULL || (output_section->flags() & elfcpp::SHF_TLS) == 0 || output_section->type() != elfcpp::SHT_NOBITS) *dot_value = dot; this->final_dot_value_ = *dot_value; this->final_dot_section_ = *dot_section; } // Print for debugging. void Output_section_element_input::print(FILE* f) const { fprintf(f, " "); if (this->keep_) fprintf(f, "KEEP("); if (!this->filename_pattern_.empty()) { bool need_close_paren = false; switch (this->filename_sort_) { case SORT_WILDCARD_NONE: break; case SORT_WILDCARD_BY_NAME: fprintf(f, "SORT_BY_NAME("); need_close_paren = true; break; default: gold_unreachable(); } fprintf(f, "%s", this->filename_pattern_.c_str()); if (need_close_paren) fprintf(f, ")"); } if (!this->input_section_patterns_.empty() || !this->filename_exclusions_.empty()) { fprintf(f, "("); bool need_space = false; if (!this->filename_exclusions_.empty()) { fprintf(f, "EXCLUDE_FILE("); bool need_comma = false; for (Filename_exclusions::const_iterator p = this->filename_exclusions_.begin(); p != this->filename_exclusions_.end(); ++p) { if (need_comma) fprintf(f, ", "); fprintf(f, "%s", p->first.c_str()); need_comma = true; } fprintf(f, ")"); need_space = true; } for (Input_section_patterns::const_iterator p = this->input_section_patterns_.begin(); p != this->input_section_patterns_.end(); ++p) { if (need_space) fprintf(f, " "); int close_parens = 0; switch (p->sort) { case SORT_WILDCARD_NONE: break; case SORT_WILDCARD_BY_NAME: fprintf(f, "SORT_BY_NAME("); close_parens = 1; break; case SORT_WILDCARD_BY_ALIGNMENT: fprintf(f, "SORT_BY_ALIGNMENT("); close_parens = 1; break; case SORT_WILDCARD_BY_NAME_BY_ALIGNMENT: fprintf(f, "SORT_BY_NAME(SORT_BY_ALIGNMENT("); close_parens = 2; break; case SORT_WILDCARD_BY_ALIGNMENT_BY_NAME: fprintf(f, "SORT_BY_ALIGNMENT(SORT_BY_NAME("); close_parens = 2; break; default: gold_unreachable(); } fprintf(f, "%s", p->pattern.c_str()); for (int i = 0; i < close_parens; ++i) fprintf(f, ")"); need_space = true; } fprintf(f, ")"); } if (this->keep_) fprintf(f, ")"); fprintf(f, "\n"); } // An output section. class Output_section_definition : public Sections_element { public: typedef Output_section_element::Input_section_list Input_section_list; Output_section_definition(const char* name, size_t namelen, const Parser_output_section_header* header); // Finish the output section with the information in the trailer. void finish(const Parser_output_section_trailer* trailer); // Add a symbol to be defined. void add_symbol_assignment(const char* name, size_t length, Expression* value, bool provide, bool hidden); // Add an assignment to the special dot symbol. void add_dot_assignment(Expression* value); // Add an assertion. void add_assertion(Expression* check, const char* message, size_t messagelen); // Add a data item to the current output section. void add_data(int size, bool is_signed, Expression* val); // Add a setting for the fill value. void add_fill(Expression* val); // Add an input section specification. void add_input_section(const Input_section_spec* spec, bool keep); // Return whether the output section is relro. bool is_relro() const { return this->is_relro_; } // Record that the output section is relro. void set_is_relro() { this->is_relro_ = true; } // Create any required output sections. void create_sections(Layout*); // Add any symbols being defined to the symbol table. void add_symbols_to_table(Symbol_table* symtab); // Finalize symbols and check assertions. void finalize_symbols(Symbol_table*, const Layout*, uint64_t*); // Return the output section name to use for an input file name and // section name. const char* output_section_name(const char* file_name, const char* section_name, Output_section***, Script_sections::Section_type*); // Initialize OSP with an output section. void orphan_section_init(Orphan_section_placement* osp, Script_sections::Elements_iterator p) { osp->output_section_init(this->name_, this->output_section_, p); } // Set the section address. void set_section_addresses(Symbol_table* symtab, Layout* layout, uint64_t* dot_value, uint64_t*, uint64_t* load_address); // Check a constraint (ONLY_IF_RO, etc.) on an output section. If // this section is constrained, and the input sections do not match, // return the constraint, and set *POSD. Section_constraint check_constraint(Output_section_definition** posd); // See if this is the alternate output section for a constrained // output section. If it is, transfer the Output_section and return // true. Otherwise return false. bool alternate_constraint(Output_section_definition*, Section_constraint); // Get the list of segments to use for an allocated section when // using a PHDRS clause. Output_section* allocate_to_segment(String_list** phdrs_list, bool* orphan); // Look for an output section by name and return the address, the // load address, the alignment, and the size. This is used when an // expression refers to an output section which was not actually // created. This returns true if the section was found, false // otherwise. bool get_output_section_info(const char*, uint64_t*, uint64_t*, uint64_t*, uint64_t*) const; // Return the associated Output_section if there is one. Output_section* get_output_section() const { return this->output_section_; } // Print the contents to the FILE. This is for debugging. void print(FILE*) const; // Return the output section type if specified or Script_sections::ST_NONE. Script_sections::Section_type section_type() const; private: static const char* script_section_type_name(Script_section_type); typedef std::vector Output_section_elements; // The output section name. std::string name_; // The address. This may be NULL. Expression* address_; // The load address. This may be NULL. Expression* load_address_; // The alignment. This may be NULL. Expression* align_; // The input section alignment. This may be NULL. Expression* subalign_; // The constraint, if any. Section_constraint constraint_; // The fill value. This may be NULL. Expression* fill_; // The list of segments this section should go into. This may be // NULL. String_list* phdrs_; // The list of elements defining the section. Output_section_elements elements_; // The Output_section created for this definition. This will be // NULL if none was created. Output_section* output_section_; // The address after it has been evaluated. uint64_t evaluated_address_; // The load address after it has been evaluated. uint64_t evaluated_load_address_; // The alignment after it has been evaluated. uint64_t evaluated_addralign_; // The output section is relro. bool is_relro_; // The output section type if specified. enum Script_section_type script_section_type_; }; // Constructor. Output_section_definition::Output_section_definition( const char* name, size_t namelen, const Parser_output_section_header* header) : name_(name, namelen), address_(header->address), load_address_(header->load_address), align_(header->align), subalign_(header->subalign), constraint_(header->constraint), fill_(NULL), phdrs_(NULL), elements_(), output_section_(NULL), evaluated_address_(0), evaluated_load_address_(0), evaluated_addralign_(0), is_relro_(false), script_section_type_(header->section_type) { } // Finish an output section. void Output_section_definition::finish(const Parser_output_section_trailer* trailer) { this->fill_ = trailer->fill; this->phdrs_ = trailer->phdrs; } // Add a symbol to be defined. void Output_section_definition::add_symbol_assignment(const char* name, size_t length, Expression* value, bool provide, bool hidden) { Output_section_element* p = new Output_section_element_assignment(name, length, value, provide, hidden); this->elements_.push_back(p); } // Add an assignment to the special dot symbol. void Output_section_definition::add_dot_assignment(Expression* value) { Output_section_element* p = new Output_section_element_dot_assignment(value); this->elements_.push_back(p); } // Add an assertion. void Output_section_definition::add_assertion(Expression* check, const char* message, size_t messagelen) { Output_section_element* p = new Output_section_element_assertion(check, message, messagelen); this->elements_.push_back(p); } // Add a data item to the current output section. void Output_section_definition::add_data(int size, bool is_signed, Expression* val) { Output_section_element* p = new Output_section_element_data(size, is_signed, val); this->elements_.push_back(p); } // Add a setting for the fill value. void Output_section_definition::add_fill(Expression* val) { Output_section_element* p = new Output_section_element_fill(val); this->elements_.push_back(p); } // Add an input section specification. void Output_section_definition::add_input_section(const Input_section_spec* spec, bool keep) { Output_section_element* p = new Output_section_element_input(spec, keep); this->elements_.push_back(p); } // Create any required output sections. We need an output section if // there is a data statement here. void Output_section_definition::create_sections(Layout* layout) { if (this->output_section_ != NULL) return; for (Output_section_elements::const_iterator p = this->elements_.begin(); p != this->elements_.end(); ++p) { if ((*p)->needs_output_section()) { const char* name = this->name_.c_str(); this->output_section_ = layout->make_output_section_for_script(name, this->section_type()); return; } } } // Add any symbols being defined to the symbol table. void Output_section_definition::add_symbols_to_table(Symbol_table* symtab) { for (Output_section_elements::iterator p = this->elements_.begin(); p != this->elements_.end(); ++p) (*p)->add_symbols_to_table(symtab); } // Finalize symbols and check assertions. void Output_section_definition::finalize_symbols(Symbol_table* symtab, const Layout* layout, uint64_t* dot_value) { if (this->output_section_ != NULL) *dot_value = this->output_section_->address(); else { uint64_t address = *dot_value; if (this->address_ != NULL) { Output_section* dummy; address = this->address_->eval_with_dot(symtab, layout, true, *dot_value, NULL, &dummy, NULL); } if (this->align_ != NULL) { Output_section* dummy; uint64_t align = this->align_->eval_with_dot(symtab, layout, true, *dot_value, NULL, &dummy, NULL); address = align_address(address, align); } *dot_value = address; } Output_section* dot_section = this->output_section_; for (Output_section_elements::iterator p = this->elements_.begin(); p != this->elements_.end(); ++p) (*p)->finalize_symbols(symtab, layout, dot_value, &dot_section); } // Return the output section name to use for an input section name. const char* Output_section_definition::output_section_name( const char* file_name, const char* section_name, Output_section*** slot, Script_sections::Section_type *psection_type) { // Ask each element whether it matches NAME. for (Output_section_elements::const_iterator p = this->elements_.begin(); p != this->elements_.end(); ++p) { if ((*p)->match_name(file_name, section_name)) { // We found a match for NAME, which means that it should go // into this output section. *slot = &this->output_section_; *psection_type = this->section_type(); return this->name_.c_str(); } } // We don't know about this section name. return NULL; } // Set the section address. Note that the OUTPUT_SECTION_ field will // be NULL if no input sections were mapped to this output section. // We still have to adjust dot and process symbol assignments. void Output_section_definition::set_section_addresses(Symbol_table* symtab, Layout* layout, uint64_t* dot_value, uint64_t* dot_alignment, uint64_t* load_address) { uint64_t address; uint64_t old_dot_value = *dot_value; uint64_t old_load_address = *load_address; // Check for --section-start. bool is_address_set = false; if (this->output_section_ != NULL) is_address_set = parameters->options().section_start(this->output_section_->name(), &address); if (!is_address_set) { if (this->address_ == NULL) address = *dot_value; else { Output_section* dummy; address = this->address_->eval_with_dot(symtab, layout, true, *dot_value, NULL, &dummy, dot_alignment); } } uint64_t align; if (this->align_ == NULL) { if (this->output_section_ == NULL) align = 0; else align = this->output_section_->addralign(); } else { Output_section* align_section; align = this->align_->eval_with_dot(symtab, layout, true, *dot_value, NULL, &align_section, NULL); if (align_section != NULL) gold_warning(_("alignment of section %s is not absolute"), this->name_.c_str()); if (this->output_section_ != NULL) this->output_section_->set_addralign(align); } address = align_address(address, align); uint64_t start_address = address; *dot_value = address; // Except for NOLOAD sections, the address of non-SHF_ALLOC sections is // forced to zero, regardless of what the linker script wants. if (this->output_section_ != NULL && ((this->output_section_->flags() & elfcpp::SHF_ALLOC) != 0 || this->output_section_->is_noload())) this->output_section_->set_address(address); this->evaluated_address_ = address; this->evaluated_addralign_ = align; if (this->load_address_ == NULL) this->evaluated_load_address_ = address; else { Output_section* dummy; uint64_t laddr = this->load_address_->eval_with_dot(symtab, layout, true, *dot_value, this->output_section_, &dummy, NULL); if (this->output_section_ != NULL) this->output_section_->set_load_address(laddr); this->evaluated_load_address_ = laddr; } uint64_t subalign; if (this->subalign_ == NULL) subalign = 0; else { Output_section* subalign_section; subalign = this->subalign_->eval_with_dot(symtab, layout, true, *dot_value, NULL, &subalign_section, NULL); if (subalign_section != NULL) gold_warning(_("subalign of section %s is not absolute"), this->name_.c_str()); } std::string fill; if (this->fill_ != NULL) { // FIXME: The GNU linker supports fill values of arbitrary // length. Output_section* fill_section; uint64_t fill_val = this->fill_->eval_with_dot(symtab, layout, true, *dot_value, NULL, &fill_section, NULL); if (fill_section != NULL) gold_warning(_("fill of section %s is not absolute"), this->name_.c_str()); unsigned char fill_buff[4]; elfcpp::Swap_unaligned<32, true>::writeval(fill_buff, fill_val); fill.assign(reinterpret_cast(fill_buff), 4); } Input_section_list input_sections; if (this->output_section_ != NULL) { // Get the list of input sections attached to this output // section. This will leave the output section with only // Output_section_data entries. address += this->output_section_->get_input_sections(address, fill, &input_sections); *dot_value = address; } Output_section* dot_section = this->output_section_; for (Output_section_elements::iterator p = this->elements_.begin(); p != this->elements_.end(); ++p) (*p)->set_section_addresses(symtab, layout, this->output_section_, subalign, dot_value, dot_alignment, &dot_section, &fill, &input_sections); gold_assert(input_sections.empty()); if (this->load_address_ == NULL || this->output_section_ == NULL) *load_address = *dot_value; else *load_address = (this->output_section_->load_address() + (*dot_value - start_address)); if (this->output_section_ != NULL) { if (this->is_relro_) this->output_section_->set_is_relro(); else this->output_section_->clear_is_relro(); // If this is a NOLOAD section, keep dot and load address unchanged. if (this->output_section_->is_noload()) { *dot_value = old_dot_value; *load_address = old_load_address; } } } // Check a constraint (ONLY_IF_RO, etc.) on an output section. If // this section is constrained, and the input sections do not match, // return the constraint, and set *POSD. Section_constraint Output_section_definition::check_constraint(Output_section_definition** posd) { switch (this->constraint_) { case CONSTRAINT_NONE: return CONSTRAINT_NONE; case CONSTRAINT_ONLY_IF_RO: if (this->output_section_ != NULL && (this->output_section_->flags() & elfcpp::SHF_WRITE) != 0) { *posd = this; return CONSTRAINT_ONLY_IF_RO; } return CONSTRAINT_NONE; case CONSTRAINT_ONLY_IF_RW: if (this->output_section_ != NULL && (this->output_section_->flags() & elfcpp::SHF_WRITE) == 0) { *posd = this; return CONSTRAINT_ONLY_IF_RW; } return CONSTRAINT_NONE; case CONSTRAINT_SPECIAL: if (this->output_section_ != NULL) gold_error(_("SPECIAL constraints are not implemented")); return CONSTRAINT_NONE; default: gold_unreachable(); } } // See if this is the alternate output section for a constrained // output section. If it is, transfer the Output_section and return // true. Otherwise return false. bool Output_section_definition::alternate_constraint( Output_section_definition* posd, Section_constraint constraint) { if (this->name_ != posd->name_) return false; switch (constraint) { case CONSTRAINT_ONLY_IF_RO: if (this->constraint_ != CONSTRAINT_ONLY_IF_RW) return false; break; case CONSTRAINT_ONLY_IF_RW: if (this->constraint_ != CONSTRAINT_ONLY_IF_RO) return false; break; default: gold_unreachable(); } // We have found the alternate constraint. We just need to move // over the Output_section. When constraints are used properly, // THIS should not have an output_section pointer, as all the input // sections should have matched the other definition. if (this->output_section_ != NULL) gold_error(_("mismatched definition for constrained sections")); this->output_section_ = posd->output_section_; posd->output_section_ = NULL; if (this->is_relro_) this->output_section_->set_is_relro(); else this->output_section_->clear_is_relro(); return true; } // Get the list of segments to use for an allocated section when using // a PHDRS clause. Output_section* Output_section_definition::allocate_to_segment(String_list** phdrs_list, bool* orphan) { // Update phdrs_list even if we don't have an output section. It // might be used by the following sections. if (this->phdrs_ != NULL) *phdrs_list = this->phdrs_; if (this->output_section_ == NULL) return NULL; if ((this->output_section_->flags() & elfcpp::SHF_ALLOC) == 0) return NULL; *orphan = false; return this->output_section_; } // Look for an output section by name and return the address, the load // address, the alignment, and the size. This is used when an // expression refers to an output section which was not actually // created. This returns true if the section was found, false // otherwise. bool Output_section_definition::get_output_section_info(const char* name, uint64_t* address, uint64_t* load_address, uint64_t* addralign, uint64_t* size) const { if (this->name_ != name) return false; if (this->output_section_ != NULL) { *address = this->output_section_->address(); if (this->output_section_->has_load_address()) *load_address = this->output_section_->load_address(); else *load_address = *address; *addralign = this->output_section_->addralign(); *size = this->output_section_->current_data_size(); } else { *address = this->evaluated_address_; *load_address = this->evaluated_load_address_; *addralign = this->evaluated_addralign_; *size = 0; } return true; } // Print for debugging. void Output_section_definition::print(FILE* f) const { fprintf(f, " %s ", this->name_.c_str()); if (this->address_ != NULL) { this->address_->print(f); fprintf(f, " "); } if (this->script_section_type_ != SCRIPT_SECTION_TYPE_NONE) fprintf(f, "(%s) ", this->script_section_type_name(this->script_section_type_)); fprintf(f, ": "); if (this->load_address_ != NULL) { fprintf(f, "AT("); this->load_address_->print(f); fprintf(f, ") "); } if (this->align_ != NULL) { fprintf(f, "ALIGN("); this->align_->print(f); fprintf(f, ") "); } if (this->subalign_ != NULL) { fprintf(f, "SUBALIGN("); this->subalign_->print(f); fprintf(f, ") "); } fprintf(f, "{\n"); for (Output_section_elements::const_iterator p = this->elements_.begin(); p != this->elements_.end(); ++p) (*p)->print(f); fprintf(f, " }"); if (this->fill_ != NULL) { fprintf(f, " = "); this->fill_->print(f); } if (this->phdrs_ != NULL) { for (String_list::const_iterator p = this->phdrs_->begin(); p != this->phdrs_->end(); ++p) fprintf(f, " :%s", p->c_str()); } fprintf(f, "\n"); } Script_sections::Section_type Output_section_definition::section_type() const { switch (this->script_section_type_) { case SCRIPT_SECTION_TYPE_NONE: return Script_sections::ST_NONE; case SCRIPT_SECTION_TYPE_NOLOAD: return Script_sections::ST_NOLOAD; case SCRIPT_SECTION_TYPE_COPY: case SCRIPT_SECTION_TYPE_DSECT: case SCRIPT_SECTION_TYPE_INFO: case SCRIPT_SECTION_TYPE_OVERLAY: // There are not really support so we treat them as ST_NONE. The // parse should have issued errors for them already. return Script_sections::ST_NONE; default: gold_unreachable(); } } // Return the name of a script section type. const char* Output_section_definition::script_section_type_name ( Script_section_type script_section_type) { switch (script_section_type) { case SCRIPT_SECTION_TYPE_NONE: return "NONE"; case SCRIPT_SECTION_TYPE_NOLOAD: return "NOLOAD"; case SCRIPT_SECTION_TYPE_DSECT: return "DSECT"; case SCRIPT_SECTION_TYPE_COPY: return "COPY"; case SCRIPT_SECTION_TYPE_INFO: return "INFO"; case SCRIPT_SECTION_TYPE_OVERLAY: return "OVERLAY"; default: gold_unreachable(); } } // An output section created to hold orphaned input sections. These // do not actually appear in linker scripts. However, for convenience // when setting the output section addresses, we put a marker to these // sections in the appropriate place in the list of SECTIONS elements. class Orphan_output_section : public Sections_element { public: Orphan_output_section(Output_section* os) : os_(os) { } // Return whether the orphan output section is relro. We can just // check the output section because we always set the flag, if // needed, just after we create the Orphan_output_section. bool is_relro() const { return this->os_->is_relro(); } // Initialize OSP with an output section. This should have been // done already. void orphan_section_init(Orphan_section_placement*, Script_sections::Elements_iterator) { gold_unreachable(); } // Set section addresses. void set_section_addresses(Symbol_table*, Layout*, uint64_t*, uint64_t*, uint64_t*); // Get the list of segments to use for an allocated section when // using a PHDRS clause. Output_section* allocate_to_segment(String_list**, bool*); // Return the associated Output_section. Output_section* get_output_section() const { return this->os_; } // Print for debugging. void print(FILE* f) const { fprintf(f, " marker for orphaned output section %s\n", this->os_->name()); } private: Output_section* os_; }; // Set section addresses. void Orphan_output_section::set_section_addresses(Symbol_table*, Layout*, uint64_t* dot_value, uint64_t*, uint64_t* load_address) { typedef std::list Input_section_list; bool have_load_address = *load_address != *dot_value; uint64_t address = *dot_value; address = align_address(address, this->os_->addralign()); if ((this->os_->flags() & elfcpp::SHF_ALLOC) != 0) { this->os_->set_address(address); if (have_load_address) this->os_->set_load_address(align_address(*load_address, this->os_->addralign())); } Input_section_list input_sections; address += this->os_->get_input_sections(address, "", &input_sections); for (Input_section_list::iterator p = input_sections.begin(); p != input_sections.end(); ++p) { uint64_t addralign = p->addralign(); if (!p->is_input_section()) p->output_section_data()->finalize_data_size(); uint64_t size = p->data_size(); address = align_address(address, addralign); this->os_->add_script_input_section(*p); address += size; } // An SHF_TLS/SHT_NOBITS section does not take up any address space. if (this->os_ == NULL || (this->os_->flags() & elfcpp::SHF_TLS) == 0 || this->os_->type() != elfcpp::SHT_NOBITS) { if (!have_load_address) *load_address = address; else *load_address += address - *dot_value; *dot_value = address; } } // Get the list of segments to use for an allocated section when using // a PHDRS clause. If this is an allocated section, return the // Output_section. We don't change the list of segments. Output_section* Orphan_output_section::allocate_to_segment(String_list**, bool* orphan) { if ((this->os_->flags() & elfcpp::SHF_ALLOC) == 0) return NULL; *orphan = true; return this->os_; } // Class Phdrs_element. A program header from a PHDRS clause. class Phdrs_element { public: Phdrs_element(const char* name, size_t namelen, unsigned int type, bool includes_filehdr, bool includes_phdrs, bool is_flags_valid, unsigned int flags, Expression* load_address) : name_(name, namelen), type_(type), includes_filehdr_(includes_filehdr), includes_phdrs_(includes_phdrs), is_flags_valid_(is_flags_valid), flags_(flags), load_address_(load_address), load_address_value_(0), segment_(NULL) { } // Return the name of this segment. const std::string& name() const { return this->name_; } // Return the type of the segment. unsigned int type() const { return this->type_; } // Whether to include the file header. bool includes_filehdr() const { return this->includes_filehdr_; } // Whether to include the program headers. bool includes_phdrs() const { return this->includes_phdrs_; } // Return whether there is a load address. bool has_load_address() const { return this->load_address_ != NULL; } // Evaluate the load address expression if there is one. void eval_load_address(Symbol_table* symtab, Layout* layout) { if (this->load_address_ != NULL) this->load_address_value_ = this->load_address_->eval(symtab, layout, true); } // Return the load address. uint64_t load_address() const { gold_assert(this->load_address_ != NULL); return this->load_address_value_; } // Create the segment. Output_segment* create_segment(Layout* layout) { this->segment_ = layout->make_output_segment(this->type_, this->flags_); return this->segment_; } // Return the segment. Output_segment* segment() { return this->segment_; } // Release the segment. void release_segment() { this->segment_ = NULL; } // Set the segment flags if appropriate. void set_flags_if_valid() { if (this->is_flags_valid_) this->segment_->set_flags(this->flags_); } // Print for debugging. void print(FILE*) const; private: // The name used in the script. std::string name_; // The type of the segment (PT_LOAD, etc.). unsigned int type_; // Whether this segment includes the file header. bool includes_filehdr_; // Whether this segment includes the section headers. bool includes_phdrs_; // Whether the flags were explicitly specified. bool is_flags_valid_; // The flags for this segment (PF_R, etc.) if specified. unsigned int flags_; // The expression for the load address for this segment. This may // be NULL. Expression* load_address_; // The actual load address from evaluating the expression. uint64_t load_address_value_; // The segment itself. Output_segment* segment_; }; // Print for debugging. void Phdrs_element::print(FILE* f) const { fprintf(f, " %s 0x%x", this->name_.c_str(), this->type_); if (this->includes_filehdr_) fprintf(f, " FILEHDR"); if (this->includes_phdrs_) fprintf(f, " PHDRS"); if (this->is_flags_valid_) fprintf(f, " FLAGS(%u)", this->flags_); if (this->load_address_ != NULL) { fprintf(f, " AT("); this->load_address_->print(f); fprintf(f, ")"); } fprintf(f, ";\n"); } // Class Script_sections. Script_sections::Script_sections() : saw_sections_clause_(false), in_sections_clause_(false), sections_elements_(NULL), output_section_(NULL), phdrs_elements_(NULL), orphan_section_placement_(NULL), data_segment_align_start_(), saw_data_segment_align_(false), saw_relro_end_(false), saw_segment_start_expression_(false) { } // Start a SECTIONS clause. void Script_sections::start_sections() { gold_assert(!this->in_sections_clause_ && this->output_section_ == NULL); this->saw_sections_clause_ = true; this->in_sections_clause_ = true; if (this->sections_elements_ == NULL) this->sections_elements_ = new Sections_elements; } // Finish a SECTIONS clause. void Script_sections::finish_sections() { gold_assert(this->in_sections_clause_ && this->output_section_ == NULL); this->in_sections_clause_ = false; } // Add a symbol to be defined. void Script_sections::add_symbol_assignment(const char* name, size_t length, Expression* val, bool provide, bool hidden) { if (this->output_section_ != NULL) this->output_section_->add_symbol_assignment(name, length, val, provide, hidden); else { Sections_element* p = new Sections_element_assignment(name, length, val, provide, hidden); this->sections_elements_->push_back(p); } } // Add an assignment to the special dot symbol. void Script_sections::add_dot_assignment(Expression* val) { if (this->output_section_ != NULL) this->output_section_->add_dot_assignment(val); else { // The GNU linker permits assignments to . to appears outside of // a SECTIONS clause, and treats it as appearing inside, so // sections_elements_ may be NULL here. if (this->sections_elements_ == NULL) { this->sections_elements_ = new Sections_elements; this->saw_sections_clause_ = true; } Sections_element* p = new Sections_element_dot_assignment(val); this->sections_elements_->push_back(p); } } // Add an assertion. void Script_sections::add_assertion(Expression* check, const char* message, size_t messagelen) { if (this->output_section_ != NULL) this->output_section_->add_assertion(check, message, messagelen); else { Sections_element* p = new Sections_element_assertion(check, message, messagelen); this->sections_elements_->push_back(p); } } // Start processing entries for an output section. void Script_sections::start_output_section( const char* name, size_t namelen, const Parser_output_section_header *header) { Output_section_definition* posd = new Output_section_definition(name, namelen, header); this->sections_elements_->push_back(posd); gold_assert(this->output_section_ == NULL); this->output_section_ = posd; } // Stop processing entries for an output section. void Script_sections::finish_output_section( const Parser_output_section_trailer* trailer) { gold_assert(this->output_section_ != NULL); this->output_section_->finish(trailer); this->output_section_ = NULL; } // Add a data item to the current output section. void Script_sections::add_data(int size, bool is_signed, Expression* val) { gold_assert(this->output_section_ != NULL); this->output_section_->add_data(size, is_signed, val); } // Add a fill value setting to the current output section. void Script_sections::add_fill(Expression* val) { gold_assert(this->output_section_ != NULL); this->output_section_->add_fill(val); } // Add an input section specification to the current output section. void Script_sections::add_input_section(const Input_section_spec* spec, bool keep) { gold_assert(this->output_section_ != NULL); this->output_section_->add_input_section(spec, keep); } // This is called when we see DATA_SEGMENT_ALIGN. It means that any // subsequent output sections may be relro. void Script_sections::data_segment_align() { if (this->saw_data_segment_align_) gold_error(_("DATA_SEGMENT_ALIGN may only appear once in a linker script")); gold_assert(!this->sections_elements_->empty()); Sections_elements::iterator p = this->sections_elements_->end(); --p; this->data_segment_align_start_ = p; this->saw_data_segment_align_ = true; } // This is called when we see DATA_SEGMENT_RELRO_END. It means that // any output sections seen since DATA_SEGMENT_ALIGN are relro. void Script_sections::data_segment_relro_end() { if (this->saw_relro_end_) gold_error(_("DATA_SEGMENT_RELRO_END may only appear once " "in a linker script")); this->saw_relro_end_ = true; if (!this->saw_data_segment_align_) gold_error(_("DATA_SEGMENT_RELRO_END must follow DATA_SEGMENT_ALIGN")); else { Sections_elements::iterator p = this->data_segment_align_start_; for (++p; p != this->sections_elements_->end(); ++p) (*p)->set_is_relro(); } } // Create any required sections. void Script_sections::create_sections(Layout* layout) { if (!this->saw_sections_clause_) return; for (Sections_elements::iterator p = this->sections_elements_->begin(); p != this->sections_elements_->end(); ++p) (*p)->create_sections(layout); } // Add any symbols we are defining to the symbol table. void Script_sections::add_symbols_to_table(Symbol_table* symtab) { if (!this->saw_sections_clause_) return; for (Sections_elements::iterator p = this->sections_elements_->begin(); p != this->sections_elements_->end(); ++p) (*p)->add_symbols_to_table(symtab); } // Finalize symbols and check assertions. void Script_sections::finalize_symbols(Symbol_table* symtab, const Layout* layout) { if (!this->saw_sections_clause_) return; uint64_t dot_value = 0; for (Sections_elements::iterator p = this->sections_elements_->begin(); p != this->sections_elements_->end(); ++p) (*p)->finalize_symbols(symtab, layout, &dot_value); } // Return the name of the output section to use for an input file name // and section name. const char* Script_sections::output_section_name( const char* file_name, const char* section_name, Output_section*** output_section_slot, Script_sections::Section_type *psection_type) { for (Sections_elements::const_iterator p = this->sections_elements_->begin(); p != this->sections_elements_->end(); ++p) { const char* ret = (*p)->output_section_name(file_name, section_name, output_section_slot, psection_type); if (ret != NULL) { // The special name /DISCARD/ means that the input section // should be discarded. if (strcmp(ret, "/DISCARD/") == 0) { *output_section_slot = NULL; *psection_type = Script_sections::ST_NONE; return NULL; } return ret; } } // If we couldn't find a mapping for the name, the output section // gets the name of the input section. *output_section_slot = NULL; *psection_type = Script_sections::ST_NONE; return section_name; } // Place a marker for an orphan output section into the SECTIONS // clause. void Script_sections::place_orphan(Output_section* os) { Orphan_section_placement* osp = this->orphan_section_placement_; if (osp == NULL) { // Initialize the Orphan_section_placement structure. osp = new Orphan_section_placement(); for (Sections_elements::iterator p = this->sections_elements_->begin(); p != this->sections_elements_->end(); ++p) (*p)->orphan_section_init(osp, p); gold_assert(!this->sections_elements_->empty()); Sections_elements::iterator last = this->sections_elements_->end(); --last; osp->last_init(last); this->orphan_section_placement_ = osp; } Orphan_output_section* orphan = new Orphan_output_section(os); // Look for where to put ORPHAN. Sections_elements::iterator* where; if (osp->find_place(os, &where)) { if ((**where)->is_relro()) os->set_is_relro(); else os->clear_is_relro(); // We want to insert ORPHAN after *WHERE, and then update *WHERE // so that the next one goes after this one. Sections_elements::iterator p = *where; gold_assert(p != this->sections_elements_->end()); ++p; *where = this->sections_elements_->insert(p, orphan); } else { os->clear_is_relro(); // We don't have a place to put this orphan section. Put it, // and all other sections like it, at the end, but before the // sections which always come at the end. Sections_elements::iterator last = osp->last_place(); *where = this->sections_elements_->insert(last, orphan); } } // Set the addresses of all the output sections. Walk through all the // elements, tracking the dot symbol. Apply assignments which set // absolute symbol values, in case they are used when setting dot. // Fill in data statement values. As we find output sections, set the // address, set the address of all associated input sections, and // update dot. Return the segment which should hold the file header // and segment headers, if any. Output_segment* Script_sections::set_section_addresses(Symbol_table* symtab, Layout* layout) { gold_assert(this->saw_sections_clause_); // Implement ONLY_IF_RO/ONLY_IF_RW constraints. These are a pain // for our representation. for (Sections_elements::iterator p = this->sections_elements_->begin(); p != this->sections_elements_->end(); ++p) { Output_section_definition* posd; Section_constraint failed_constraint = (*p)->check_constraint(&posd); if (failed_constraint != CONSTRAINT_NONE) { Sections_elements::iterator q; for (q = this->sections_elements_->begin(); q != this->sections_elements_->end(); ++q) { if (q != p) { if ((*q)->alternate_constraint(posd, failed_constraint)) break; } } if (q == this->sections_elements_->end()) gold_error(_("no matching section constraint")); } } // Force the alignment of the first TLS section to be the maximum // alignment of all TLS sections. Output_section* first_tls = NULL; uint64_t tls_align = 0; for (Sections_elements::const_iterator p = this->sections_elements_->begin(); p != this->sections_elements_->end(); ++p) { Output_section *os = (*p)->get_output_section(); if (os != NULL && (os->flags() & elfcpp::SHF_TLS) != 0) { if (first_tls == NULL) first_tls = os; if (os->addralign() > tls_align) tls_align = os->addralign(); } } if (first_tls != NULL) first_tls->set_addralign(tls_align); // For a relocatable link, we implicitly set dot to zero. uint64_t dot_value = 0; uint64_t dot_alignment = 0; uint64_t load_address = 0; // Check to see if we want to use any of -Ttext, -Tdata and -Tbss options // to set section addresses. If the script has any SEGMENT_START // expression, we do not set the section addresses. bool use_tsection_options = (!this->saw_segment_start_expression_ && (parameters->options().user_set_Ttext() || parameters->options().user_set_Tdata() || parameters->options().user_set_Tbss())); for (Sections_elements::iterator p = this->sections_elements_->begin(); p != this->sections_elements_->end(); ++p) { Output_section* os = (*p)->get_output_section(); // Handle -Ttext, -Tdata and -Tbss options. We do this by looking for // the special sections by names and doing dot assignments. if (use_tsection_options && os != NULL && (os->flags() & elfcpp::SHF_ALLOC) != 0) { uint64_t new_dot_value = dot_value; if (parameters->options().user_set_Ttext() && strcmp(os->name(), ".text") == 0) new_dot_value = parameters->options().Ttext(); else if (parameters->options().user_set_Tdata() && strcmp(os->name(), ".data") == 0) new_dot_value = parameters->options().Tdata(); else if (parameters->options().user_set_Tbss() && strcmp(os->name(), ".bss") == 0) new_dot_value = parameters->options().Tbss(); // Update dot and load address if necessary. if (new_dot_value < dot_value) gold_error(_("dot may not move backward")); else if (new_dot_value != dot_value) { dot_value = new_dot_value; load_address = new_dot_value; } } (*p)->set_section_addresses(symtab, layout, &dot_value, &dot_alignment, &load_address); } if (this->phdrs_elements_ != NULL) { for (Phdrs_elements::iterator p = this->phdrs_elements_->begin(); p != this->phdrs_elements_->end(); ++p) (*p)->eval_load_address(symtab, layout); } return this->create_segments(layout, dot_alignment); } // Sort the sections in order to put them into segments. class Sort_output_sections { public: bool operator()(const Output_section* os1, const Output_section* os2) const; }; bool Sort_output_sections::operator()(const Output_section* os1, const Output_section* os2) const { // Sort first by the load address. uint64_t lma1 = (os1->has_load_address() ? os1->load_address() : os1->address()); uint64_t lma2 = (os2->has_load_address() ? os2->load_address() : os2->address()); if (lma1 != lma2) return lma1 < lma2; // Then sort by the virtual address. if (os1->address() != os2->address()) return os1->address() < os2->address(); // Sort TLS sections to the end. bool tls1 = (os1->flags() & elfcpp::SHF_TLS) != 0; bool tls2 = (os2->flags() & elfcpp::SHF_TLS) != 0; if (tls1 != tls2) return tls2; // Sort PROGBITS before NOBITS. if (os1->type() == elfcpp::SHT_PROGBITS && os2->type() == elfcpp::SHT_NOBITS) return true; if (os1->type() == elfcpp::SHT_NOBITS && os2->type() == elfcpp::SHT_PROGBITS) return false; // Sort non-NOLOAD before NOLOAD. if (os1->is_noload() && !os2->is_noload()) return true; if (!os1->is_noload() && os2->is_noload()) return true; // Otherwise we don't care. return false; } // Return whether OS is a BSS section. This is a SHT_NOBITS section. // We treat a section with the SHF_TLS flag set as taking up space // even if it is SHT_NOBITS (this is true of .tbss), as we allocate // space for them in the file. bool Script_sections::is_bss_section(const Output_section* os) { return (os->type() == elfcpp::SHT_NOBITS && (os->flags() & elfcpp::SHF_TLS) == 0); } // Return the size taken by the file header and the program headers. size_t Script_sections::total_header_size(Layout* layout) const { size_t segment_count = layout->segment_count(); size_t file_header_size; size_t segment_headers_size; if (parameters->target().get_size() == 32) { file_header_size = elfcpp::Elf_sizes<32>::ehdr_size; segment_headers_size = segment_count * elfcpp::Elf_sizes<32>::phdr_size; } else if (parameters->target().get_size() == 64) { file_header_size = elfcpp::Elf_sizes<64>::ehdr_size; segment_headers_size = segment_count * elfcpp::Elf_sizes<64>::phdr_size; } else gold_unreachable(); return file_header_size + segment_headers_size; } // Return the amount we have to subtract from the LMA to accomodate // headers of the given size. The complication is that the file // header have to be at the start of a page, as otherwise it will not // be at the start of the file. uint64_t Script_sections::header_size_adjustment(uint64_t lma, size_t sizeof_headers) const { const uint64_t abi_pagesize = parameters->target().abi_pagesize(); uint64_t hdr_lma = lma - sizeof_headers; hdr_lma &= ~(abi_pagesize - 1); return lma - hdr_lma; } // Create the PT_LOAD segments when using a SECTIONS clause. Returns // the segment which should hold the file header and segment headers, // if any. Output_segment* Script_sections::create_segments(Layout* layout, uint64_t dot_alignment) { gold_assert(this->saw_sections_clause_); if (parameters->options().relocatable()) return NULL; if (this->saw_phdrs_clause()) return create_segments_from_phdrs_clause(layout, dot_alignment); Layout::Section_list sections; layout->get_allocated_sections(§ions); // Sort the sections by address. std::stable_sort(sections.begin(), sections.end(), Sort_output_sections()); this->create_note_and_tls_segments(layout, §ions); // Walk through the sections adding them to PT_LOAD segments. const uint64_t abi_pagesize = parameters->target().abi_pagesize(); Output_segment* first_seg = NULL; Output_segment* current_seg = NULL; bool is_current_seg_readonly = true; Layout::Section_list::iterator plast = sections.end(); uint64_t last_vma = 0; uint64_t last_lma = 0; uint64_t last_size = 0; for (Layout::Section_list::iterator p = sections.begin(); p != sections.end(); ++p) { const uint64_t vma = (*p)->address(); const uint64_t lma = ((*p)->has_load_address() ? (*p)->load_address() : vma); const uint64_t size = (*p)->current_data_size(); bool need_new_segment; if (current_seg == NULL) need_new_segment = true; else if (lma - vma != last_lma - last_vma) { // This section has a different LMA relationship than the // last one; we need a new segment. need_new_segment = true; } else if (align_address(last_lma + last_size, abi_pagesize) < align_address(lma, abi_pagesize)) { // Putting this section in the segment would require // skipping a page. need_new_segment = true; } else if (is_bss_section(*plast) && !is_bss_section(*p)) { // A non-BSS section can not follow a BSS section in the // same segment. need_new_segment = true; } else if (is_current_seg_readonly && ((*p)->flags() & elfcpp::SHF_WRITE) != 0 && !parameters->options().omagic()) { // Don't put a writable section in the same segment as a // non-writable section. need_new_segment = true; } else { // Otherwise, reuse the existing segment. need_new_segment = false; } elfcpp::Elf_Word seg_flags = Layout::section_flags_to_segment((*p)->flags()); if (need_new_segment) { current_seg = layout->make_output_segment(elfcpp::PT_LOAD, seg_flags); current_seg->set_addresses(vma, lma); current_seg->set_minimum_p_align(dot_alignment); if (first_seg == NULL) first_seg = current_seg; is_current_seg_readonly = true; } current_seg->add_output_section(*p, seg_flags, false); if (((*p)->flags() & elfcpp::SHF_WRITE) != 0) is_current_seg_readonly = false; plast = p; last_vma = vma; last_lma = lma; last_size = size; } // An ELF program should work even if the program headers are not in // a PT_LOAD segment. However, it appears that the Linux kernel // does not set the AT_PHDR auxiliary entry in that case. It sets // the load address to p_vaddr - p_offset of the first PT_LOAD // segment. It then sets AT_PHDR to the load address plus the // offset to the program headers, e_phoff in the file header. This // fails when the program headers appear in the file before the // first PT_LOAD segment. Therefore, we always create a PT_LOAD // segment to hold the file header and the program headers. This is // effectively what the GNU linker does, and it is slightly more // efficient in any case. We try to use the first PT_LOAD segment // if we can, otherwise we make a new one. if (first_seg == NULL) return NULL; // -n or -N mean that the program is not demand paged and there is // no need to put the program headers in a PT_LOAD segment. if (parameters->options().nmagic() || parameters->options().omagic()) return NULL; size_t sizeof_headers = this->total_header_size(layout); uint64_t vma = first_seg->vaddr(); uint64_t lma = first_seg->paddr(); uint64_t subtract = this->header_size_adjustment(lma, sizeof_headers); if ((lma & (abi_pagesize - 1)) >= sizeof_headers) { first_seg->set_addresses(vma - subtract, lma - subtract); return first_seg; } // If there is no room to squeeze in the headers, then punt. The // resulting executable probably won't run on GNU/Linux, but we // trust that the user knows what they are doing. if (lma < subtract || vma < subtract) return NULL; Output_segment* load_seg = layout->make_output_segment(elfcpp::PT_LOAD, elfcpp::PF_R); load_seg->set_addresses(vma - subtract, lma - subtract); return load_seg; } // Create a PT_NOTE segment for each SHT_NOTE section and a PT_TLS // segment if there are any SHT_TLS sections. void Script_sections::create_note_and_tls_segments( Layout* layout, const Layout::Section_list* sections) { gold_assert(!this->saw_phdrs_clause()); bool saw_tls = false; for (Layout::Section_list::const_iterator p = sections->begin(); p != sections->end(); ++p) { if ((*p)->type() == elfcpp::SHT_NOTE) { elfcpp::Elf_Word seg_flags = Layout::section_flags_to_segment((*p)->flags()); Output_segment* oseg = layout->make_output_segment(elfcpp::PT_NOTE, seg_flags); oseg->add_output_section(*p, seg_flags, false); // Incorporate any subsequent SHT_NOTE sections, in the // hopes that the script is sensible. Layout::Section_list::const_iterator pnext = p + 1; while (pnext != sections->end() && (*pnext)->type() == elfcpp::SHT_NOTE) { seg_flags = Layout::section_flags_to_segment((*pnext)->flags()); oseg->add_output_section(*pnext, seg_flags, false); p = pnext; ++pnext; } } if (((*p)->flags() & elfcpp::SHF_TLS) != 0) { if (saw_tls) gold_error(_("TLS sections are not adjacent")); elfcpp::Elf_Word seg_flags = Layout::section_flags_to_segment((*p)->flags()); Output_segment* oseg = layout->make_output_segment(elfcpp::PT_TLS, seg_flags); oseg->add_output_section(*p, seg_flags, false); Layout::Section_list::const_iterator pnext = p + 1; while (pnext != sections->end() && ((*pnext)->flags() & elfcpp::SHF_TLS) != 0) { seg_flags = Layout::section_flags_to_segment((*pnext)->flags()); oseg->add_output_section(*pnext, seg_flags, false); p = pnext; ++pnext; } saw_tls = true; } } } // Add a program header. The PHDRS clause is syntactically distinct // from the SECTIONS clause, but we implement it with the SECTIONS // support because PHDRS is useless if there is no SECTIONS clause. void Script_sections::add_phdr(const char* name, size_t namelen, unsigned int type, bool includes_filehdr, bool includes_phdrs, bool is_flags_valid, unsigned int flags, Expression* load_address) { if (this->phdrs_elements_ == NULL) this->phdrs_elements_ = new Phdrs_elements(); this->phdrs_elements_->push_back(new Phdrs_element(name, namelen, type, includes_filehdr, includes_phdrs, is_flags_valid, flags, load_address)); } // Return the number of segments we expect to create based on the // SECTIONS clause. This is used to implement SIZEOF_HEADERS. size_t Script_sections::expected_segment_count(const Layout* layout) const { if (this->saw_phdrs_clause()) return this->phdrs_elements_->size(); Layout::Section_list sections; layout->get_allocated_sections(§ions); // We assume that we will need two PT_LOAD segments. size_t ret = 2; bool saw_note = false; bool saw_tls = false; for (Layout::Section_list::const_iterator p = sections.begin(); p != sections.end(); ++p) { if ((*p)->type() == elfcpp::SHT_NOTE) { // Assume that all note sections will fit into a single // PT_NOTE segment. if (!saw_note) { ++ret; saw_note = true; } } else if (((*p)->flags() & elfcpp::SHF_TLS) != 0) { // There can only be one PT_TLS segment. if (!saw_tls) { ++ret; saw_tls = true; } } } return ret; } // Create the segments from a PHDRS clause. Return the segment which // should hold the file header and program headers, if any. Output_segment* Script_sections::create_segments_from_phdrs_clause(Layout* layout, uint64_t dot_alignment) { this->attach_sections_using_phdrs_clause(layout); return this->set_phdrs_clause_addresses(layout, dot_alignment); } // Create the segments from the PHDRS clause, and put the output // sections in them. void Script_sections::attach_sections_using_phdrs_clause(Layout* layout) { typedef std::map Name_to_segment; Name_to_segment name_to_segment; for (Phdrs_elements::const_iterator p = this->phdrs_elements_->begin(); p != this->phdrs_elements_->end(); ++p) name_to_segment[(*p)->name()] = (*p)->create_segment(layout); // Walk through the output sections and attach them to segments. // Output sections in the script which do not list segments are // attached to the same set of segments as the immediately preceding // output section. String_list* phdr_names = NULL; bool load_segments_only = false; for (Sections_elements::const_iterator p = this->sections_elements_->begin(); p != this->sections_elements_->end(); ++p) { bool orphan; String_list* old_phdr_names = phdr_names; Output_section* os = (*p)->allocate_to_segment(&phdr_names, &orphan); if (os == NULL) continue; if (phdr_names == NULL) { gold_error(_("allocated section not in any segment")); continue; } // We see a list of segments names. Disable PT_LOAD segment only // filtering. if (old_phdr_names != phdr_names) load_segments_only = false; // If this is an orphan section--one that was not explicitly // mentioned in the linker script--then it should not inherit // any segment type other than PT_LOAD. Otherwise, e.g., the // PT_INTERP segment will pick up following orphan sections, // which does not make sense. If this is not an orphan section, // we trust the linker script. if (orphan) { // Enable PT_LOAD segments only filtering until we see another // list of segment names. load_segments_only = true; } bool in_load_segment = false; for (String_list::const_iterator q = phdr_names->begin(); q != phdr_names->end(); ++q) { Name_to_segment::const_iterator r = name_to_segment.find(*q); if (r == name_to_segment.end()) gold_error(_("no segment %s"), q->c_str()); else { if (load_segments_only && r->second->type() != elfcpp::PT_LOAD) continue; elfcpp::Elf_Word seg_flags = Layout::section_flags_to_segment(os->flags()); r->second->add_output_section(os, seg_flags, false); if (r->second->type() == elfcpp::PT_LOAD) { if (in_load_segment) gold_error(_("section in two PT_LOAD segments")); in_load_segment = true; } } } if (!in_load_segment) gold_error(_("allocated section not in any PT_LOAD segment")); } } // Set the addresses for segments created from a PHDRS clause. Return // the segment which should hold the file header and program headers, // if any. Output_segment* Script_sections::set_phdrs_clause_addresses(Layout* layout, uint64_t dot_alignment) { Output_segment* load_seg = NULL; for (Phdrs_elements::const_iterator p = this->phdrs_elements_->begin(); p != this->phdrs_elements_->end(); ++p) { // Note that we have to set the flags after adding the output // sections to the segment, as adding an output segment can // change the flags. (*p)->set_flags_if_valid(); Output_segment* oseg = (*p)->segment(); if (oseg->type() != elfcpp::PT_LOAD) { // The addresses of non-PT_LOAD segments are set from the // PT_LOAD segments. if ((*p)->has_load_address()) gold_error(_("may only specify load address for PT_LOAD segment")); continue; } oseg->set_minimum_p_align(dot_alignment); // The output sections should have addresses from the SECTIONS // clause. The addresses don't have to be in order, so find the // one with the lowest load address. Use that to set the // address of the segment. Output_section* osec = oseg->section_with_lowest_load_address(); if (osec == NULL) { oseg->set_addresses(0, 0); continue; } uint64_t vma = osec->address(); uint64_t lma = osec->has_load_address() ? osec->load_address() : vma; // Override the load address of the section with the load // address specified for the segment. if ((*p)->has_load_address()) { if (osec->has_load_address()) gold_warning(_("PHDRS load address overrides " "section %s load address"), osec->name()); lma = (*p)->load_address(); } bool headers = (*p)->includes_filehdr() && (*p)->includes_phdrs(); if (!headers && ((*p)->includes_filehdr() || (*p)->includes_phdrs())) { // We could support this if we wanted to. gold_error(_("using only one of FILEHDR and PHDRS is " "not currently supported")); } if (headers) { size_t sizeof_headers = this->total_header_size(layout); uint64_t subtract = this->header_size_adjustment(lma, sizeof_headers); if (lma >= subtract && vma >= subtract) { lma -= subtract; vma -= subtract; } else { gold_error(_("sections loaded on first page without room " "for file and program headers " "are not supported")); } if (load_seg != NULL) gold_error(_("using FILEHDR and PHDRS on more than one " "PT_LOAD segment is not currently supported")); load_seg = oseg; } oseg->set_addresses(vma, lma); } return load_seg; } // Add the file header and segment headers to non-load segments // specified in the PHDRS clause. void Script_sections::put_headers_in_phdrs(Output_data* file_header, Output_data* segment_headers) { gold_assert(this->saw_phdrs_clause()); for (Phdrs_elements::iterator p = this->phdrs_elements_->begin(); p != this->phdrs_elements_->end(); ++p) { if ((*p)->type() != elfcpp::PT_LOAD) { if ((*p)->includes_phdrs()) (*p)->segment()->add_initial_output_data(segment_headers); if ((*p)->includes_filehdr()) (*p)->segment()->add_initial_output_data(file_header); } } } // Look for an output section by name and return the address, the load // address, the alignment, and the size. This is used when an // expression refers to an output section which was not actually // created. This returns true if the section was found, false // otherwise. bool Script_sections::get_output_section_info(const char* name, uint64_t* address, uint64_t* load_address, uint64_t* addralign, uint64_t* size) const { if (!this->saw_sections_clause_) return false; for (Sections_elements::const_iterator p = this->sections_elements_->begin(); p != this->sections_elements_->end(); ++p) if ((*p)->get_output_section_info(name, address, load_address, addralign, size)) return true; return false; } // Release all Output_segments. This remove all pointers to all // Output_segments. void Script_sections::release_segments() { if (this->saw_phdrs_clause()) { for (Phdrs_elements::const_iterator p = this->phdrs_elements_->begin(); p != this->phdrs_elements_->end(); ++p) (*p)->release_segment(); } } // Print the SECTIONS clause to F for debugging. void Script_sections::print(FILE* f) const { if (!this->saw_sections_clause_) return; fprintf(f, "SECTIONS {\n"); for (Sections_elements::const_iterator p = this->sections_elements_->begin(); p != this->sections_elements_->end(); ++p) (*p)->print(f); fprintf(f, "}\n"); if (this->phdrs_elements_ != NULL) { fprintf(f, "PHDRS {\n"); for (Phdrs_elements::const_iterator p = this->phdrs_elements_->begin(); p != this->phdrs_elements_->end(); ++p) (*p)->print(f); fprintf(f, "}\n"); } } } // End namespace gold.