rocket-tools/fsf-binutils-gdb.git - Unnamed repository; edit this file 'description' to name the repository.

Age	Commit message (Expand)	Author	Files	Lines
2000-06-15	Synced with libiberty in the gcc repository.	H.J. Lu	1	-0/+71

// symtab.h -- the gold symbol table -*- C++ -*- // Copyright 2006, 2007, 2008 Free Software Foundation, Inc. // Written by Ian Lance Taylor <iant@google.com>. // This file is part of gold. // This program is free software; you can redistribute it and/or modify // it under the terms of the GNU General Public License as published by // the Free Software Foundation; either version 3 of the License, or // (at your option) any later version. // This program is distributed in the hope that it will be useful, // but WITHOUT ANY WARRANTY; without even the implied warranty of // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the // GNU General Public License for more details. // You should have received a copy of the GNU General Public License // along with this program; if not, write to the Free Software // Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, // MA 02110-1301, USA. // Symbol_table // The symbol table. #include <string> #include <utility> #include <vector> #include "elfcpp.h" #include "parameters.h" #include "stringpool.h" #include "object.h" #ifndef GOLD_SYMTAB_H #define GOLD_SYMTAB_H namespace gold { class Mapfile; class Object; class Relobj; template<int size, bool big_endian> class Sized_relobj; template<int size, bool big_endian> class Sized_pluginobj; class Dynobj; template<int size, bool big_endian> class Sized_dynobj; class Versions; class Version_script_info; class Input_objects; class Output_data; class Output_section; class Output_segment; class Output_file; class Output_symtab_xindex; // The base class of an entry in the symbol table. The symbol table // can have a lot of entries, so we don't want this class to big. // Size dependent fields can be found in the template class // Sized_symbol. Targets may support their own derived classes. class Symbol { public: // Because we want the class to be small, we don't use any virtual // functions. But because symbols can be defined in different // places, we need to classify them. This enum is the different // sources of symbols we support. enum Source { // Symbol defined in a relocatable or dynamic input file--this is // the most common case. FROM_OBJECT, // Symbol defined in an Output_data, a special section created by // the target. IN_OUTPUT_DATA, // Symbol defined in an Output_segment, with no associated // section. IN_OUTPUT_SEGMENT, // Symbol value is constant. IS_CONSTANT, // Symbol is undefined. IS_UNDEFINED }; // When the source is IN_OUTPUT_SEGMENT, we need to describe what // the offset means. enum Segment_offset_base { // From the start of the segment. SEGMENT_START, // From the end of the segment. SEGMENT_END, // From the filesz of the segment--i.e., after the loaded bytes // but before the bytes which are allocated but zeroed. SEGMENT_BSS }; // Return the symbol name. const char* name() const { return this->name_; } // Return the (ANSI) demangled version of the name, if // parameters.demangle() is true. Otherwise, return the name. This // is intended to be used only for logging errors, so it's not // super-efficient. std::string demangled_name() const; // Return the symbol version. This will return NULL for an // unversioned symbol. const char* version() const { return this->version_; } // Return whether this version is the default for this symbol name // (eg, "foo@@V2" is a default version; "foo@V1" is not). Only // meaningful for versioned symbols. bool is_default() const { gold_assert(this->version_ != NULL); return this->is_def_; } // Set that this version is the default for this symbol name. void set_is_default() { this->is_def_ = true; } // Return the symbol source. Source source() const { return this->source_; } // Return the object with which this symbol is associated. Object* object() const { gold_assert(this->source_ == FROM_OBJECT); return this->u_.from_object.object; } // Return the index of the section in the input relocatable or // dynamic object file. unsigned int shndx(bool* is_ordinary) const { gold_assert(this->source_ == FROM_OBJECT); *is_ordinary = this->is_ordinary_shndx_; return this->u_.from_object.shndx; } // Return the output data section with which this symbol is // associated, if the symbol was specially defined with respect to // an output data section. Output_data* output_data() const { gold_assert(this->source_ == IN_OUTPUT_DATA); return this->u_.in_output_data.output_data; } // If this symbol was defined with respect to an output data // section, return whether the value is an offset from end. bool offset_is_from_end() const { gold_assert(this->source_ == IN_OUTPUT_DATA); return this->u_.in_output_data.offset_is_from_end; } // Return the output segment with which this symbol is associated, // if the symbol was specially defined with respect to an output // segment. Output_segment* output_segment() const { gold_assert(this->source_ == IN_OUTPUT_SEGMENT); return this->u_.in_output_segment.output_segment; } // If this symbol was defined with respect to an output segment, // return the offset base. Segment_offset_base offset_base() const { gold_assert(this->source_ == IN_OUTPUT_SEGMENT); return this->u_.in_output_segment.offset_base; } // Return the symbol binding. elfcpp::STB binding() const { return this->binding_; } // Return the symbol type. elfcpp::STT type() const { return this->type_; } // Return the symbol visibility. elfcpp::STV visibility() const { return this->visibility_; } // Return the non-visibility part of the st_other field. unsigned char nonvis() const { return this->nonvis_; } // Return whether this symbol is a forwarder. This will never be // true of a symbol found in the hash table, but may be true of // symbol pointers attached to object files. bool is_forwarder() const { return this->is_forwarder_; } // Mark this symbol as a forwarder. void set_forwarder() { this->is_forwarder_ = true; } // Return whether this symbol has an alias in the weak aliases table // in Symbol_table. bool has_alias() const { return this->has_alias_; } // Mark this symbol as having an alias. void set_has_alias() { this->has_alias_ = true; } // Return whether this symbol needs an entry in the dynamic symbol // table. bool needs_dynsym_entry() const { return (this->needs_dynsym_entry_ || (this->in_reg() && this->in_dyn())); } // Mark this symbol as needing an entry in the dynamic symbol table. void set_needs_dynsym_entry() { this->needs_dynsym_entry_ = true; } // Return whether this symbol should be added to the dynamic symbol // table. bool should_add_dynsym_entry() const; // Return whether this symbol has been seen in a regular object. bool in_reg() const { return this->in_reg_; } // Mark this symbol as having been seen in a regular object. void set_in_reg() { this->in_reg_ = true; } // Return whether this symbol has been seen in a dynamic object. bool in_dyn() const { return this->in_dyn_; } // Mark this symbol as having been seen in a dynamic object. void set_in_dyn() { this->in_dyn_ = true; } // Return whether this symbol has been seen in a real ELF object. // (IN_REG will return TRUE if the symbol has been seen in either // a real ELF object or an object claimed by a plugin.) bool in_real_elf() const { return this->in_real_elf_; } // Mark this symbol as having been seen in a real ELF object. void set_in_real_elf() { this->in_real_elf_ = true; } // Return the index of this symbol in the output file symbol table. // A value of -1U means that this symbol is not going into the // output file. This starts out as zero, and is set to a non-zero // value by Symbol_table::finalize. It is an error to ask for the // symbol table index before it has been set. unsigned int symtab_index() const { gold_assert(this->symtab_index_ != 0); return this->symtab_index_; } // Set the index of the symbol in the output file symbol table. void set_symtab_index(unsigned int index) { gold_assert(index != 0); this->symtab_index_ = index; } // Return whether this symbol already has an index in the output // file symbol table. bool has_symtab_index() const { return this->symtab_index_ != 0; } // Return the index of this symbol in the dynamic symbol table. A // value of -1U means that this symbol is not going into the dynamic // symbol table. This starts out as zero, and is set to a non-zero // during Layout::finalize. It is an error to ask for the dynamic // symbol table index before it has been set. unsigned int dynsym_index() const { gold_assert(this->dynsym_index_ != 0); return this->dynsym_index_; } // Set the index of the symbol in the dynamic symbol table. void set_dynsym_index(unsigned int index) { gold_assert(index != 0); this->dynsym_index_ = index; } // Return whether this symbol already has an index in the dynamic // symbol table. bool has_dynsym_index() const { return this->dynsym_index_ != 0; } // Return whether this symbol has an entry in the GOT section. // For a TLS symbol, this GOT entry will hold its tp-relative offset. bool has_got_offset(unsigned int got_type) const { return this->got_offsets_.get_offset(got_type) != -1U; } // Return the offset into the GOT section of this symbol. unsigned int got_offset(unsigned int got_type) const { unsigned int got_offset = this->got_offsets_.get_offset(got_type); gold_assert(got_offset != -1U); return got_offset; } // Set the GOT offset of this symbol. void set_got_offset(unsigned int got_type, unsigned int got_offset) { this->got_offsets_.set_offset(got_type, got_offset); } // Return whether this symbol has an entry in the PLT section. bool has_plt_offset() const { return this->has_plt_offset_; } // Return the offset into the PLT section of this symbol. unsigned int plt_offset() const { gold_assert(this->has_plt_offset()); return this->plt_offset_; } // Set the PLT offset of this symbol. void set_plt_offset(unsigned int plt_offset) { this->has_plt_offset_ = true; this->plt_offset_ = plt_offset; } // Return whether this dynamic symbol needs a special value in the // dynamic symbol table. bool needs_dynsym_value() const { return this->needs_dynsym_value_; } // Set that this dynamic symbol needs a special value in the dynamic // symbol table. void set_needs_dynsym_value() { gold_assert(this->object()->is_dynamic()); this->needs_dynsym_value_ = true; } // Return true if the final value of this symbol is known at link // time. bool final_value_is_known() const; // Return whether this is a defined symbol (not undefined or // common). bool is_defined() const { bool is_ordinary; if (this->source_ != FROM_OBJECT) return this->source_ != IS_UNDEFINED; unsigned int shndx = this->shndx(&is_ordinary); return (is_ordinary ? shndx != elfcpp::SHN_UNDEF : shndx != elfcpp::SHN_COMMON); } // Return true if this symbol is from a dynamic object. bool is_from_dynobj() const { return this->source_ == FROM_OBJECT && this->object()->is_dynamic(); } // Return whether this is an undefined symbol. bool is_undefined() const { bool is_ordinary; return ((this->source_ == FROM_OBJECT && this->shndx(&is_ordinary) == elfcpp::SHN_UNDEF && is_ordinary) || this->source_ == IS_UNDEFINED); } // Return whether this is a weak undefined symbol. bool is_weak_undefined() const { return this->is_undefined() && this->binding() == elfcpp::STB_WEAK; } // Return whether this is an absolute symbol. bool is_absolute() const { bool is_ordinary; return ((this->source_ == FROM_OBJECT && this->shndx(&is_ordinary) == elfcpp::SHN_ABS && !is_ordinary) || this->source_ == IS_CONSTANT); } // Return whether this is a common symbol. bool is_common() const { bool is_ordinary; return (this->source_ == FROM_OBJECT && ((this->shndx(&is_ordinary) == elfcpp::SHN_COMMON && !is_ordinary) || this->type_ == elfcpp::STT_COMMON)); } // Return whether this symbol can be seen outside this object. bool is_externally_visible() const { return (this->visibility_ == elfcpp::STV_DEFAULT || this->visibility_ == elfcpp::STV_PROTECTED); } // Return true if this symbol can be preempted by a definition in // another link unit. bool is_preemptible() const { // It doesn't make sense to ask whether a symbol defined in // another object is preemptible. gold_assert(!this->is_from_dynobj()); // It doesn't make sense to ask whether an undefined symbol // is preemptible. gold_assert(!this->is_undefined()); // If a symbol does not have default visibility, it can not be // seen outside this link unit and therefore is not preemptible. if (this->visibility_ != elfcpp::STV_DEFAULT) return false; // If this symbol has been forced to be a local symbol by a // version script, then it is not visible outside this link unit // and is not preemptible. if (this->is_forced_local_) return false; // If we are not producing a shared library, then nothing is // preemptible. if (!parameters->options().shared()) return false; // If the user used -Bsymbolic, then nothing is preemptible. if (parameters->options().Bsymbolic()) return false; // If the user used -Bsymbolic-functions, then functions are not // preemptible. We explicitly check for not being STT_OBJECT, // rather than for being STT_FUNC, because that is what the GNU // linker does. if (this->type() != elfcpp::STT_OBJECT && parameters->options().Bsymbolic_functions()) return false; // Otherwise the symbol is preemptible. return true; } // Return true if this symbol is a function that needs a PLT entry. // If the symbol is defined in a dynamic object or if it is subject // to pre-emption, we need to make a PLT entry. If we're doing a // static link, we don't create PLT entries. bool needs_plt_entry() const { return (!parameters->doing_static_link() && this->type() == elfcpp::STT_FUNC && (this->is_from_dynobj() || this->is_undefined() || this->is_preemptible())); } // When determining whether a reference to a symbol needs a dynamic // relocation, we need to know several things about the reference. // These flags may be or'ed together. enum Reference_flags { // Reference to the symbol's absolute address. ABSOLUTE_REF = 1, // A non-PIC reference. NON_PIC_REF = 2, // A function call. FUNCTION_CALL = 4 }; // Given a direct absolute or pc-relative static relocation against // the global symbol, this function returns whether a dynamic relocation // is needed. bool needs_dynamic_reloc(int flags) const { // No dynamic relocations in a static link! if (parameters->doing_static_link()) return false; // A reference to a weak undefined symbol from an executable should be // statically resolved to 0, and does not need a dynamic relocation. // This matches gnu ld behavior. if (this->is_weak_undefined() && !parameters->options().shared()) return false; // A reference to an absolute symbol does not need a dynamic relocation. if (this->is_absolute()) return false; // An absolute reference within a position-independent output file // will need a dynamic relocation. if ((flags & ABSOLUTE_REF) && parameters->options().output_is_position_independent()) return true; // A function call that can branch to a local PLT entry does not need // a dynamic relocation. A non-pic pc-relative function call in a // shared library cannot use a PLT entry. if ((flags & FUNCTION_CALL) && this->has_plt_offset() && !((flags & NON_PIC_REF) && parameters->options().shared())) return false; // A reference to any PLT entry in a non-position-independent executable // does not need a dynamic relocation. if (!parameters->options().output_is_position_independent() && this->has_plt_offset()) return false; // A reference to a symbol defined in a dynamic object or to a // symbol that is preemptible will need a dynamic relocation. if (this->is_from_dynobj() || this->is_undefined() || this->is_preemptible()) return true; // For all other cases, return FALSE. return false; } // Whether we should use the PLT offset associated with a symbol for // a relocation. IS_NON_PIC_REFERENCE is true if this is a non-PIC // reloc--the same set of relocs for which we would pass NON_PIC_REF // to the needs_dynamic_reloc function. bool use_plt_offset(bool is_non_pic_reference) const { // If the symbol doesn't have a PLT offset, then naturally we // don't want to use it. if (!this->has_plt_offset()) return false; // If we are going to generate a dynamic relocation, then we will // wind up using that, so no need to use the PLT entry. if (this->needs_dynamic_reloc(FUNCTION_CALL | (is_non_pic_reference ? NON_PIC_REF : 0))) return false; // If the symbol is from a dynamic object, we need to use the PLT // entry. if (this->is_from_dynobj()) return true; // If we are generating a shared object, and this symbol is // undefined or preemptible, we need to use the PLT entry. if (parameters->options().shared() && (this->is_undefined() || this->is_preemptible())) return true; // If this is a weak undefined symbol, we need to use the PLT // entry; the symbol may be defined by a library loaded at // runtime. if (this->is_weak_undefined()) return true; // Otherwise we can use the regular definition. return false; } // Given a direct absolute static relocation against // the global symbol, where a dynamic relocation is needed, this // function returns whether a relative dynamic relocation can be used. // The caller must determine separately whether the static relocation // is compatible with a relative relocation. bool can_use_relative_reloc(bool is_function_call) const { // A function call that can branch to a local PLT entry can // use a RELATIVE relocation. if (is_function_call && this->has_plt_offset()) return true; // A reference to a symbol defined in a dynamic object or to a // symbol that is preemptible can not use a RELATIVE relocaiton. if (this->is_from_dynobj() || this->is_undefined() || this->is_preemptible()) return false; // For all other cases, return TRUE. return true; } // Return the output section where this symbol is defined. Return // NULL if the symbol has an absolute value. Output_section* output_section() const; // Set the symbol's output section. This is used for symbols // defined in scripts. This should only be called after the symbol // table has been finalized. void set_output_section(Output_section*); // Return whether there should be a warning for references to this // symbol. bool has_warning() const { return this->has_warning_; } // Mark this symbol as having a warning. void set_has_warning() { this->has_warning_ = true; } // Return whether this symbol is defined by a COPY reloc from a // dynamic object. bool is_copied_from_dynobj() const { return this->is_copied_from_dynobj_; } // Mark this symbol as defined by a COPY reloc. void set_is_copied_from_dynobj() { this->is_copied_from_dynobj_ = true; } // Return whether this symbol is forced to visibility STB_LOCAL // by a "local:" entry in a version script. bool is_forced_local() const { return this->is_forced_local_; } // Mark this symbol as forced to STB_LOCAL visibility. void set_is_forced_local() { this->is_forced_local_ = true; } protected: // Instances of this class should always be created at a specific // size. Symbol() { memset(this, 0, sizeof *this); } // Initialize the general fields. void init_fields(const char* name, const char* version, elfcpp::STT type, elfcpp::STB binding, elfcpp::STV visibility, unsigned char nonvis); // Initialize fields from an ELF symbol in OBJECT. ST_SHNDX is the // section index, IS_ORDINARY is whether it is a normal section // index rather than a special code. template<int size, bool big_endian> void init_base_object(const char *name, const char* version, Object* object, const elfcpp::Sym<size, big_endian>&, unsigned int st_shndx, bool is_ordinary); // Initialize fields for an Output_data. void init_base_output_data(const char* name, const char* version, Output_data*, elfcpp::STT, elfcpp::STB, elfcpp::STV, unsigned char nonvis, bool offset_is_from_end); // Initialize fields for an Output_segment. void init_base_output_segment(const char* name, const char* version, Output_segment* os, elfcpp::STT type, elfcpp::STB binding, elfcpp::STV visibility, unsigned char nonvis, Segment_offset_base offset_base); // Initialize fields for a constant. void init_base_constant(const char* name, const char* version, elfcpp::STT type, elfcpp::STB binding, elfcpp::STV visibility, unsigned char nonvis); // Initialize fields for an undefined symbol. void init_base_undefined(const char* name, const char* version, elfcpp::STT type, elfcpp::STB binding, elfcpp::STV visibility, unsigned char nonvis); // Override existing symbol. template<int size, bool big_endian> void override_base(const elfcpp::Sym<size, big_endian>&, unsigned int st_shndx, bool is_ordinary, Object* object, const char* version); // Override existing symbol with a special symbol. void override_base_with_special(const Symbol* from); // Override symbol version. void override_version(const char* version); // Allocate a common symbol by giving it a location in the output // file. void allocate_base_common(Output_data*); private: Symbol(const Symbol&); Symbol& operator=(const Symbol&); // Symbol name (expected to point into a Stringpool). const char* name_; // Symbol version (expected to point into a Stringpool). This may // be NULL. const char* version_; union { // This struct is used if SOURCE_ == FROM_OBJECT. struct { // Object in which symbol is defined, or in which it was first // seen. Object* object; // Section number in object_ in which symbol is defined. unsigned int shndx; } from_object; // This struct is used if SOURCE_ == IN_OUTPUT_DATA. struct { // Output_data in which symbol is defined. Before // Layout::finalize the symbol's value is an offset within the // Output_data. Output_data* output_data; // True if the offset is from the end, false if the offset is // from the beginning. bool offset_is_from_end; } in_output_data; // This struct is used if SOURCE_ == IN_OUTPUT_SEGMENT. struct { // Output_segment in which the symbol is defined. Before // Layout::finalize the symbol's value is an offset. Output_segment* output_segment; // The base to use for the offset before Layout::finalize. Segment_offset_base offset_base; } in_output_segment; } u_; // The index of this symbol in the output file. If the symbol is // not going into the output file, this value is -1U. This field // starts as always holding zero. It is set to a non-zero value by // Symbol_table::finalize. unsigned int symtab_index_; // The index of this symbol in the dynamic symbol table. If the // symbol is not going into the dynamic symbol table, this value is // -1U. This field starts as always holding zero. It is set to a // non-zero value during Layout::finalize. unsigned int dynsym_index_; // If this symbol has an entry in the GOT section (has_got_offset_ // is true), this holds the offset from the start of the GOT section. // A symbol may have more than one GOT offset (e.g., when mixing // modules compiled with two different TLS models), but will usually // have at most one. Got_offset_list got_offsets_; // If this symbol has an entry in the PLT section (has_plt_offset_ // is true), then this is the offset from the start of the PLT // section. unsigned int plt_offset_; // Symbol type (bits 0 to 3). elfcpp::STT type_ : 4; // Symbol binding (bits 4 to 7). elfcpp::STB binding_ : 4; // Symbol visibility (bits 8 to 9). elfcpp::STV visibility_ : 2; // Rest of symbol st_other field (bits 10 to 15). unsigned int nonvis_ : 6; // The type of symbol (bits 16 to 18). Source source_ : 3; // True if this symbol always requires special target-specific // handling (bit 19). bool is_target_special_ : 1; // True if this is the default version of the symbol (bit 20). bool is_def_ : 1; // True if this symbol really forwards to another symbol. This is // used when we discover after the fact that two different entries // in the hash table really refer to the same symbol. This will // never be set for a symbol found in the hash table, but may be set // for a symbol found in the list of symbols attached to an Object. // It forwards to the symbol found in the forwarders_ map of // Symbol_table (bit 21). bool is_forwarder_ : 1; // True if the symbol has an alias in the weak_aliases table in // Symbol_table (bit 22). bool has_alias_ : 1; // True if this symbol needs to be in the dynamic symbol table (bit // 23). bool needs_dynsym_entry_ : 1; // True if we've seen this symbol in a regular object (bit 24). bool in_reg_ : 1; // True if we've seen this symbol in a dynamic object (bit 25). bool in_dyn_ : 1; // True if the symbol has an entry in the PLT section (bit 26). bool has_plt_offset_ : 1; // True if this is a dynamic symbol which needs a special value in // the dynamic symbol table (bit 27). bool needs_dynsym_value_ : 1; // True if there is a warning for this symbol (bit 28). bool has_warning_ : 1; // True if we are using a COPY reloc for this symbol, so that the // real definition lives in a dynamic object (bit 29). bool is_copied_from_dynobj_ : 1; // True if this symbol was forced to local visibility by a version // script (bit 30). bool is_forced_local_ : 1; // True if the field u_.from_object.shndx is an ordinary section // index, not one of the special codes from SHN_LORESERVE to // SHN_HIRESERVE (bit 31). bool is_ordinary_shndx_ : 1; // True if we've seen this symbol in a real ELF object. bool in_real_elf_ : 1; }; // The parts of a symbol which are size specific. Using a template // derived class like this helps us use less space on a 32-bit system. template<int size> class Sized_symbol : public Symbol { public: typedef typename elfcpp::Elf_types<size>::Elf_Addr Value_type; typedef typename elfcpp::Elf_types<size>::Elf_WXword Size_type; Sized_symbol() { } // Initialize fields from an ELF symbol in OBJECT. ST_SHNDX is the // section index, IS_ORDINARY is whether it is a normal section // index rather than a special code. template<bool big_endian> void init_object(const char *name, const char* version, Object* object, const elfcpp::Sym<size, big_endian>&, unsigned int st_shndx, bool is_ordinary); // Initialize fields for an Output_data. void init_output_data(const char* name, const char* version, Output_data*, Value_type value, Size_type symsize, elfcpp::STT, elfcpp::STB, elfcpp::STV, unsigned char nonvis, bool offset_is_from_end); // Initialize fields for an Output_segment. void init_output_segment(const char* name, const char* version, Output_segment*, Value_type value, Size_type symsize, elfcpp::STT, elfcpp::STB, elfcpp::STV, unsigned char nonvis, Segment_offset_base offset_base); // Initialize fields for a constant. void init_constant(const char* name, const char* version, Value_type value, Size_type symsize, elfcpp::STT, elfcpp::STB, elfcpp::STV, unsigned char nonvis); // Initialize fields for an undefined symbol. void init_undefined(const char* name, const char* version, elfcpp::STT, elfcpp::STB, elfcpp::STV, unsigned char nonvis); // Override existing symbol. template<bool big_endian> void override(const elfcpp::Sym<size, big_endian>&, unsigned int st_shndx, bool is_ordinary, Object* object, const char* version); // Override existing symbol with a special symbol. void override_with_special(const Sized_symbol<size>*); // Return the symbol's value. Value_type value() const { return this->value_; } // Return the symbol's size (we can't call this 'size' because that // is a template parameter). Size_type symsize() const { return this->symsize_; } // Set the symbol size. This is used when resolving common symbols. void set_symsize(Size_type symsize) { this->symsize_ = symsize; } // Set the symbol value. This is called when we store the final // values of the symbols into the symbol table. void set_value(Value_type value) { this->value_ = value; } // Allocate a common symbol by giving it a location in the output // file. void allocate_common(Output_data*, Value_type value); private: Sized_symbol(const Sized_symbol&); Sized_symbol& operator=(const Sized_symbol&); // Symbol value. Before Layout::finalize this is the offset in the // input section. This is set to the final value during // Layout::finalize. Value_type value_; // Symbol size. Size_type symsize_; }; // A struct describing a symbol defined by the linker, where the value // of the symbol is defined based on an output section. This is used // for symbols defined by the linker, like "_init_array_start". struct Define_symbol_in_section { // The symbol name. const char* name; // The name of the output section with which this symbol should be // associated. If there is no output section with that name, the // symbol will be defined as zero. const char* output_section; // The offset of the symbol within the output section. This is an // offset from the start of the output section, unless start_at_end // is true, in which case this is an offset from the end of the // output section. uint64_t value; // The size of the symbol. uint64_t size; // The symbol type. elfcpp::STT type; // The symbol binding. elfcpp::STB binding; // The symbol visibility. elfcpp::STV visibility; // The rest of the st_other field. unsigned char nonvis; // If true, the value field is an offset from the end of the output // section. bool offset_is_from_end; // If true, this symbol is defined only if we see a reference to it. bool only_if_ref; }; // A struct describing a symbol defined by the linker, where the value // of the symbol is defined based on a segment. This is used for // symbols defined by the linker, like "_end". We describe the // segment with which the symbol should be associated by its // characteristics. If no segment meets these characteristics, the // symbol will be defined as zero. If there is more than one segment // which meets these characteristics, we will use the first one. struct Define_symbol_in_segment { // The symbol name. const char* name; // The segment type where the symbol should be defined, typically // PT_LOAD. elfcpp::PT segment_type; // Bitmask of segment flags which must be set. elfcpp::PF segment_flags_set; // Bitmask of segment flags which must be clear. elfcpp::PF segment_flags_clear; // The offset of the symbol within the segment. The offset is // calculated from the position set by offset_base. uint64_t value; // The size of the symbol. uint64_t size; // The symbol type. elfcpp::STT type; // The symbol binding. elfcpp::STB binding; // The symbol visibility. elfcpp::STV visibility; // The rest of the st_other field. unsigned char nonvis; // The base from which we compute the offset. Symbol::Segment_offset_base offset_base; // If true, this symbol is defined only if we see a reference to it. bool only_if_ref; }; // This class manages warnings. Warnings are a GNU extension. When // we see a section named .gnu.warning.SYM in an object file, and if // we wind using the definition of SYM from that object file, then we // will issue a warning for any relocation against SYM from a // different object file. The text of the warning is the contents of // the section. This is not precisely the definition used by the old // GNU linker; the old GNU linker treated an occurrence of // .gnu.warning.SYM as defining a warning symbol. A warning symbol // would trigger a warning on any reference. However, it was // inconsistent in that a warning in a dynamic object only triggered // if there was no definition in a regular object. This linker is // different in that we only issue a warning if we use the symbol // definition from the same object file as the warning section. class Warnings { public: Warnings() : warnings_() { } // Add a warning for symbol NAME in object OBJ. WARNING is the text // of the warning. void add_warning(Symbol_table* symtab, const char* name, Object* obj, const std::string& warning); // For each symbol for which we should give a warning, make a note // on the symbol. void note_warnings(Symbol_table* symtab); // Issue a warning for a reference to SYM at RELINFO's location. template<int size, bool big_endian> void issue_warning(const Symbol* sym, const Relocate_info<size, big_endian>*, size_t relnum, off_t reloffset) const; private: Warnings(const Warnings&); Warnings& operator=(const Warnings&); // What we need to know to get the warning text. struct Warning_location { // The object the warning is in. Object* object; // The warning text. std::string text; Warning_location() : object(NULL), text() { } void set(Object* o, const std::string& t) { this->object = o; this->text = t; } }; // A mapping from warning symbol names (canonicalized in // Symbol_table's namepool_ field) to warning information. typedef Unordered_map<const char*, Warning_location> Warning_table; Warning_table warnings_; }; // The main linker symbol table. class Symbol_table { public: // COUNT is an estimate of how many symbosl will be inserted in the // symbol table. It's ok to put 0 if you don't know; a correct // guess will just save some CPU by reducing hashtable resizes. Symbol_table(unsigned int count, const Version_script_info& version_script); ~Symbol_table(); // Add COUNT external symbols from the relocatable object RELOBJ to // the symbol table. SYMS is the symbols, SYMNDX_OFFSET is the // offset in the symbol table of the first symbol, SYM_NAMES is // their names, SYM_NAME_SIZE is the size of SYM_NAMES. This sets // SYMPOINTERS to point to the symbols in the symbol table. It sets // *DEFINED to the number of defined symbols. template<int size, bool big_endian> void add_from_relobj(Sized_relobj<size, big_endian>* relobj, const unsigned char* syms, size_t count, size_t symndx_offset, const char* sym_names, size_t sym_name_size, typename Sized_relobj<size, big_endian>::Symbols*, size_t* defined); // Add one external symbol from the plugin object OBJ to the symbol table. // Returns a pointer to the resolved symbol in the symbol table. template<int size, bool big_endian> Symbol* add_from_pluginobj(Sized_pluginobj<size, big_endian>* obj, const char* name, const char* ver, elfcpp::Sym<size, big_endian>* sym); // Add COUNT dynamic symbols from the dynamic object DYNOBJ to the // symbol table. SYMS is the symbols. SYM_NAMES is their names. // SYM_NAME_SIZE is the size of SYM_NAMES. The other parameters are // symbol version data. template<int size, bool big_endian> void add_from_dynobj(Sized_dynobj<size, big_endian>* dynobj, const unsigned char* syms, size_t count, const char* sym_names, size_t sym_name_size, const unsigned char* versym, size_t versym_size, const std::vector<const char*>*, typename Sized_relobj<size, big_endian>::Symbols*, size_t* defined); // Define a special symbol based on an Output_data. It is a // multiple definition error if this symbol is already defined. Symbol* define_in_output_data(const char* name, const char* version, Output_data*, uint64_t value, uint64_t symsize, elfcpp::STT type, elfcpp::STB binding, elfcpp::STV visibility, unsigned char nonvis, bool offset_is_from_end, bool only_if_ref); // Define a special symbol based on an Output_segment. It is a // multiple definition error if this symbol is already defined. Symbol* define_in_output_segment(const char* name, const char* version, Output_segment*, uint64_t value, uint64_t symsize, elfcpp::STT type, elfcpp::STB binding, elfcpp::STV visibility, unsigned char nonvis, Symbol::Segment_offset_base, bool only_if_ref); // Define a special symbol with a constant value. It is a multiple // definition error if this symbol is already defined. Symbol* define_as_constant(const char* name, const char* version, uint64_t value, uint64_t symsize, elfcpp::STT type, elfcpp::STB binding, elfcpp::STV visibility, unsigned char nonvis, bool only_if_ref, bool force_override); // Define a set of symbols in output sections. If ONLY_IF_REF is // true, only define them if they are referenced. void define_symbols(const Layout*, int count, const Define_symbol_in_section*, bool only_if_ref); // Define a set of symbols in output segments. If ONLY_IF_REF is // true, only defined them if they are referenced. void define_symbols(const Layout*, int count, const Define_symbol_in_segment*, bool only_if_ref); // Define SYM using a COPY reloc. POSD is the Output_data where the // symbol should be defined--typically a .dyn.bss section. VALUE is // the offset within POSD. template<int size> void define_with_copy_reloc(Sized_symbol<size>* sym, Output_data* posd, typename elfcpp::Elf_types<size>::Elf_Addr); // Look up a symbol. Symbol* lookup(const char*, const char* version = NULL) const; // Return the real symbol associated with the forwarder symbol FROM. Symbol* resolve_forwards(const Symbol* from) const; // Return the sized version of a symbol in this table. template<int size> Sized_symbol<size>* get_sized_symbol(Symbol*) const; template<int size> const Sized_symbol<size>* get_sized_symbol(const Symbol*) const; // Return the count of undefined symbols seen. int saw_undefined() const { return this->saw_undefined_; } // Allocate the common symbols void allocate_commons(Layout*, Mapfile*); // Add a warning for symbol NAME in object OBJ. WARNING is the text // of the warning. void add_warning(const char* name, Object* obj, const std::string& warning) { this->warnings_.add_warning(this, name, obj, warning); } // Canonicalize a symbol name for use in the hash table. const char* canonicalize_name(const char* name) { return this->namepool_.add(name, true, NULL); } // Possibly issue a warning for a reference to SYM at LOCATION which // is in OBJ. template<int size, bool big_endian> void issue_warning(const Symbol* sym, const Relocate_info<size, big_endian>* relinfo, size_t relnum, off_t reloffset) const { this->warnings_.issue_warning(sym, relinfo, relnum, reloffset); } // Check candidate_odr_violations_ to find symbols with the same name // but apparently different definitions (different source-file/line-no). void detect_odr_violations(const Task*, const char* output_file_name) const; // Add any undefined symbols named on the command line to the symbol // table. void add_undefined_symbols_from_command_line(); // SYM is defined using a COPY reloc. Return the dynamic object // where the original definition was found. Dynobj* get_copy_source(const Symbol* sym) const; // Set the dynamic symbol indexes. INDEX is the index of the first // global dynamic symbol. Pointers to the symbols are stored into // the vector. The names are stored into the Stringpool. This // returns an updated dynamic symbol index. unsigned int set_dynsym_indexes(unsigned int index, std::vector<Symbol*>*, Stringpool*, Versions*); // Finalize the symbol table after we have set the final addresses // of all the input sections. This sets the final symbol indexes, // values and adds the names to *POOL. *PLOCAL_SYMCOUNT is the // index of the first global symbol. OFF is the file offset of the // global symbol table, DYNOFF is the offset of the globals in the // dynamic symbol table, DYN_GLOBAL_INDEX is the index of the first // global dynamic symbol, and DYNCOUNT is the number of global // dynamic symbols. This records the parameters, and returns the // new file offset. It updates *PLOCAL_SYMCOUNT if it created any // local symbols. off_t finalize(off_t off, off_t dynoff, size_t dyn_global_index, size_t dyncount, Stringpool* pool, unsigned int *plocal_symcount); // Write out the global symbols. void write_globals(const Input_objects*, const Stringpool*, const Stringpool*, Output_symtab_xindex*, Output_symtab_xindex*, Output_file*) const; // Write out a section symbol. Return the updated offset. void write_section_symbol(const Output_section*, Output_symtab_xindex*, Output_file*, off_t) const; // Dump statistical information to stderr. void print_stats() const; // Return the version script information. const Version_script_info& version_script() const { return version_script_; } private: Symbol_table(const Symbol_table&); Symbol_table& operator=(const Symbol_table&); // The type of the list of common symbols. typedef std::vector<Symbol*> Commons_type; // Make FROM a forwarder symbol to TO. void make_forwarder(Symbol* from, Symbol* to); // Add a symbol. template<int size, bool big_endian> Sized_symbol<size>* add_from_object(Object*, const char *name, Stringpool::Key name_key, const char *version, Stringpool::Key version_key, bool def, const elfcpp::Sym<size, big_endian>& sym, unsigned int st_shndx, bool is_ordinary, unsigned int orig_st_shndx); // Resolve symbols. template<int size, bool big_endian> void resolve(Sized_symbol<size>* to, const elfcpp::Sym<size, big_endian>& sym, unsigned int st_shndx, bool is_ordinary, unsigned int orig_st_shndx, Object*, const char* version); template<int size, bool big_endian> void resolve(Sized_symbol<size>* to, const Sized_symbol<size>* from); // Record that a symbol is forced to be local by a version script. void force_local(Symbol*); // Adjust NAME and *NAME_KEY for wrapping. const char* wrap_symbol(Object* object, const char*, Stringpool::Key* name_key); // Whether we should override a symbol, based on flags in // resolve.cc. static bool should_override(const Symbol*, unsigned int, Object*, bool*); // Override a symbol. template<int size, bool big_endian> void override(Sized_symbol<size>* tosym, const elfcpp::Sym<size, big_endian>& fromsym, unsigned int st_shndx, bool is_ordinary, Object* object, const char* version); // Whether we should override a symbol with a special symbol which // is automatically defined by the linker. static bool should_override_with_special(const Symbol*); // Override a symbol with a special symbol. template<int size> void override_with_special(Sized_symbol<size>* tosym, const Sized_symbol<size>* fromsym); // Record all weak alias sets for a dynamic object. template<int size> void record_weak_aliases(std::vector<Sized_symbol<size>*>*); // Define a special symbol. template<int size, bool big_endian> Sized_symbol<size>* define_special_symbol(const char** pname, const char** pversion, bool only_if_ref, Sized_symbol<size>** poldsym); // Define a symbol in an Output_data, sized version. template<int size> Sized_symbol<size>* do_define_in_output_data(const char* name, const char* version, Output_data*, typename elfcpp::Elf_types<size>::Elf_Addr value, typename elfcpp::Elf_types<size>::Elf_WXword ssize, elfcpp::STT type, elfcpp::STB binding, elfcpp::STV visibility, unsigned char nonvis, bool offset_is_from_end, bool only_if_ref); // Define a symbol in an Output_segment, sized version. template<int size> Sized_symbol<size>* do_define_in_output_segment( const char* name, const char* version, Output_segment* os, typename elfcpp::Elf_types<size>::Elf_Addr value, typename elfcpp::Elf_types<size>::Elf_WXword ssize, elfcpp::STT type, elfcpp::STB binding, elfcpp::STV visibility, unsigned char nonvis, Symbol::Segment_offset_base offset_base, bool only_if_ref); // Define a symbol as a constant, sized version. template<int size> Sized_symbol<size>* do_define_as_constant( const char* name, const char* version, typename elfcpp::Elf_types<size>::Elf_Addr value, typename elfcpp::Elf_types<size>::Elf_WXword ssize, elfcpp::STT type, elfcpp::STB binding, elfcpp::STV visibility, unsigned char nonvis, bool only_if_ref, bool force_override); // Add any undefined symbols named on the command line to the symbol // table, sized version. template<int size> void do_add_undefined_symbols_from_command_line(); // Allocate the common symbols, sized version. template<int size> void do_allocate_commons(Layout*, Mapfile*); // Allocate the common symbols from one list. template<int size> void do_allocate_commons_list(Layout*, bool is_tls, Commons_type*, Mapfile*); // Implement detect_odr_violations. template<int size, bool big_endian> void sized_detect_odr_violations() const; // Finalize symbols specialized for size. template<int size> off_t sized_finalize(off_t, Stringpool*, unsigned int*); // Finalize a symbol. Return whether it should be added to the // symbol table. template<int size> bool sized_finalize_symbol(Symbol*); // Add a symbol the final symtab by setting its index. template<int size> void add_to_final_symtab(Symbol*, Stringpool*, unsigned int* pindex, off_t* poff); // Write globals specialized for size and endianness. template<int size, bool big_endian> void sized_write_globals(const Input_objects*, const Stringpool*, const Stringpool*, Output_symtab_xindex*, Output_symtab_xindex*, Output_file*) const; // Write out a symbol to P. template<int size, bool big_endian> void sized_write_symbol(Sized_symbol<size>*, typename elfcpp::Elf_types<size>::Elf_Addr value, unsigned int shndx, const Stringpool*, unsigned char* p) const; // Possibly warn about an undefined symbol from a dynamic object. void warn_about_undefined_dynobj_symbol(const Input_objects*, Symbol*) const; // Write out a section symbol, specialized for size and endianness. template<int size, bool big_endian> void sized_write_section_symbol(const Output_section*, Output_symtab_xindex*, Output_file*, off_t) const; // The type of the symbol hash table. typedef std::pair<Stringpool::Key, Stringpool::Key> Symbol_table_key; struct Symbol_table_hash { size_t operator()(const Symbol_table_key&) const; }; struct Symbol_table_eq { bool operator()(const Symbol_table_key&, const Symbol_table_key&) const; }; typedef Unordered_map<Symbol_table_key, Symbol*, Symbol_table_hash, Symbol_table_eq> Symbol_table_type; // The type of the list of symbols which have been forced local. typedef std::vector<Symbol*> Forced_locals; // A map from symbols with COPY relocs to the dynamic objects where // they are defined. typedef Unordered_map<const Symbol*, Dynobj*> Copied_symbol_dynobjs; // A map from symbol name (as a pointer into the namepool) to all // the locations the symbols is (weakly) defined (and certain other // conditions are met). This map will be used later to detect // possible One Definition Rule (ODR) violations. struct Symbol_location { Object* object; // Object where the symbol is defined. unsigned int shndx; // Section-in-object where the symbol is defined. off_t offset; // Offset-in-section where the symbol is defined. bool operator==(const Symbol_location& that) const { return (this->object == that.object && this->shndx == that.shndx && this->offset == that.offset); } }; struct Symbol_location_hash { size_t operator()(const Symbol_location& loc) const { return reinterpret_cast<uintptr_t>(loc.object) ^ loc.offset ^ loc.shndx; } }; typedef Unordered_map<const char*, Unordered_set<Symbol_location, Symbol_location_hash> > Odr_map; // We increment this every time we see a new undefined symbol, for // use in archive groups. int saw_undefined_; // The index of the first global symbol in the output file. unsigned int first_global_index_; // The file offset within the output symtab section where we should // write the table. off_t offset_; // The number of global symbols we want to write out. unsigned int output_count_; // The file offset of the global dynamic symbols, or 0 if none. off_t dynamic_offset_; // The index of the first global dynamic symbol. unsigned int first_dynamic_global_index_; // The number of global dynamic symbols, or 0 if none. unsigned int dynamic_count_; // The symbol hash table. Symbol_table_type table_; // A pool of symbol names. This is used for all global symbols. // Entries in the hash table point into this pool. Stringpool namepool_; // Forwarding symbols. Unordered_map<const Symbol*, Symbol*> forwarders_; // Weak aliases. A symbol in this list points to the next alias. // The aliases point to each other in a circular list. Unordered_map<Symbol*, Symbol*> weak_aliases_; // We don't expect there to be very many common symbols, so we keep // a list of them. When we find a common symbol we add it to this // list. It is possible that by the time we process the list the // symbol is no longer a common symbol. It may also have become a // forwarder. Commons_type commons_; // This is like the commons_ field, except that it holds TLS common // symbols. Commons_type tls_commons_; // A list of symbols which have been forced to be local. We don't // expect there to be very many of them, so we keep a list of them // rather than walking the whole table to find them. Forced_locals forced_locals_; // Manage symbol warnings. Warnings warnings_; // Manage potential One Definition Rule (ODR) violations. Odr_map candidate_odr_violations_; // When we emit a COPY reloc for a symbol, we define it in an // Output_data. When it's time to emit version information for it, // we need to know the dynamic object in which we found the original // definition. This maps symbols with COPY relocs to the dynamic // object where they were defined. Copied_symbol_dynobjs copied_symbol_dynobjs_; // Information parsed from the version script, if any. const Version_script_info& version_script_; }; // We inline get_sized_symbol for efficiency. template<int size> Sized_symbol<size>* Symbol_table::get_sized_symbol(Symbol* sym) const { gold_assert(size == parameters->target().get_size()); return static_cast<Sized_symbol<size>*>(sym); } template<int size> const Sized_symbol<size>* Symbol_table::get_sized_symbol(const Symbol* sym) const { gold_assert(size == parameters->target().get_size()); return static_cast<const Sized_symbol<size>*>(sym); } } // End namespace gold. #endif // !defined(GOLD_SYMTAB_H)