// symtab.h -- the gold symbol table -*- C++ -*-
+// Copyright 2006, 2007 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 "gold.h"
-
#include <string>
#include <utility>
+#include <vector>
#include "elfcpp.h"
-#include "targetsize.h"
+#include "parameters.h"
+#include "stringpool.h"
#include "object.h"
-#include "workqueue.h"
#ifndef GOLD_SYMTAB_H
#define GOLD_SYMTAB_H
namespace gold
{
-// An entry in the symbol table. The symbol table can have a lot of
-// entries, so we don't want this class to get too big.
+class Object;
+class Relobj;
+template<int size, bool big_endian>
+class Sized_relobj;
+class Dynobj;
+template<int size, bool big_endian>
+class Sized_dynobj;
+class Versions;
+class Input_objects;
+class Output_data;
+class Output_section;
+class Output_segment;
+class Output_file;
+class Target;
+
+// 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.
-template<int size>
class Symbol
{
public:
- typedef typename elfcpp::Elf_types<size>::Elf_Addr Value;
- typedef typename Size_types<size>::Unsigned_type Size;
+ // 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.
+ CONSTANT
+ };
+
+ // 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 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() const
+ {
+ gold_assert(this->source_ == FROM_OBJECT);
+ 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 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() const
+ { return this->has_got_offset_; }
+
+ // Return the offset into the GOT section of this symbol.
+ unsigned int
+ got_offset() const
+ {
+ gold_assert(this->has_got_offset());
+ return this->got_offset_;
+ }
+
+ // Set the GOT offset of this symbol.
+ void
+ set_got_offset(unsigned int got_offset)
+ {
+ this->has_got_offset_ = true;
+ this->got_offset_ = got_offset;
+ }
+
+ // Return whether this TLS symbol has an entry in the GOT section for
+ // its module index or, if NEED_PAIR is true, has a pair of entries
+ // for its module index and dtv-relative offset.
+ bool
+ has_tls_got_offset(bool need_pair) const
+ {
+ return (this->has_tls_mod_got_offset_
+ && (!need_pair || this->has_tls_pair_got_offset_));
+ }
+
+ // Return the offset into the GOT section for this symbol's TLS module
+ // index or, if NEED_PAIR is true, for the pair of entries for the
+ // module index and dtv-relative offset.
+ unsigned int
+ tls_got_offset(bool need_pair) const
+ {
+ gold_assert(this->has_tls_got_offset(need_pair));
+ return this->tls_mod_got_offset_;
+ }
+
+ // Set the GOT offset of this symbol.
+ void
+ set_tls_got_offset(unsigned int got_offset, bool have_pair)
+ {
+ this->has_tls_mod_got_offset_ = true;
+ this->has_tls_pair_got_offset_ = have_pair;
+ this->tls_mod_got_offset_ = 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
+ {
+ return (this->source_ != FROM_OBJECT
+ || (this->shndx() != elfcpp::SHN_UNDEF
+ && this->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
+ {
+ return this->source_ == FROM_OBJECT && this->shndx() == elfcpp::SHN_UNDEF;
+ }
+
+ // Return whether this is a common symbol.
+ bool
+ is_common() const
+ {
+ return (this->source_ == FROM_OBJECT
+ && (this->shndx() == elfcpp::SHN_COMMON
+ || 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());
+
+ return (this->visibility_ != elfcpp::STV_INTERNAL
+ && this->visibility_ != elfcpp::STV_HIDDEN
+ && this->visibility_ != elfcpp::STV_PROTECTED
+ && parameters->output_is_shared()
+ && !parameters->symbolic());
+ }
+
+ // 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.
+ bool
+ needs_plt_entry() const
+ {
+ return (this->type() == elfcpp::STT_FUNC
+ && (this->is_from_dynobj() || this->is_preemptible()));
+ }
+
+ // 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(bool is_absolute_ref, bool is_function_call) const
+ {
+ // An absolute reference within a position-independent output file
+ // will need a dynamic relocaion.
+ if (is_absolute_ref && parameters->output_is_position_independent())
+ return true;
+
+ // A function call that can branch to a local PLT entry does not need
+ // a dynamic relocation.
+ if (is_function_call && this->has_plt_offset())
+ return false;
+
+ // A reference to any PLT entry in a non-position-independent executable
+ // does not need a dynamic relocation.
+ if (!parameters->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_preemptible())
+ return true;
+
+ // For all other cases, return FALSE.
+ 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_preemptible())
+ return false;
+
+ // For all other cases, return TRUE.
+ return true;
+ }
+
+ // 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; }
+
+ 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.
+ template<int size, bool big_endian>
+ void
+ init_base(const char *name, const char* version, Object* object,
+ const elfcpp::Sym<size, big_endian>&);
+
+ // Initialize fields for an Output_data.
+ void
+ init_base(const char* name, 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(const char* name, 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(const char* name, 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>&, Object* object,
+ const char* version);
+
+ // Override existing symbol with a special symbol.
+ void
+ override_base_with_special(const Symbol* from);
+
+ // Allocate a common symbol by giving it a location in the output
+ // file.
+ void
+ allocate_base_common(Output_data*);
private:
- // Every symbol has a unique name, more or less, so we use
- // std::string for the name. There are only a few versions in a
- // given link, so for them we point into a pool.
- std::string name_;
+ 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_;
- Object* object_;
- unsigned int shnum_;
- Value value_;
- Size size_;
+
+ 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 is the offset from the start of the GOT section.
+ // For a TLS symbol, if has_tls_tpoff_got_offset_ is true, this
+ // serves as the GOT offset for the GOT entry that holds its
+ // TP-relative offset.
+ unsigned int got_offset_;
+
+ // If this is a TLS symbol and has an entry in the GOT section
+ // for a module index or a pair of entries (module index,
+ // dtv-relative offset), these are the offsets from the start
+ // of the GOT section.
+ unsigned int tls_mod_got_offset_;
+ unsigned int tls_pair_got_offset_;
+
+ // 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.
elfcpp::STT type_ : 4;
+ // Symbol binding.
elfcpp::STB binding_ : 4;
- elfcpp:STV visibility_ : 2;
- unsigned int other_ : 6;
+ // Symbol visibility.
+ elfcpp::STV visibility_ : 2;
+ // Rest of symbol st_other field.
+ unsigned int nonvis_ : 6;
+ // The type of symbol.
+ Source source_ : 3;
+ // True if this symbol always requires special target-specific
+ // handling.
+ bool is_target_special_ : 1;
+ // True if this is the default version of the symbol.
+ 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.
+ bool is_forwarder_ : 1;
+ // True if the symbol has an alias in the weak_aliases table in
+ // Symbol_table.
+ bool has_alias_ : 1;
+ // True if this symbol needs to be in the dynamic symbol table.
+ bool needs_dynsym_entry_ : 1;
+ // True if we've seen this symbol in a regular object.
+ bool in_reg_ : 1;
+ // True if we've seen this symbol in a dynamic object.
+ bool in_dyn_ : 1;
+ // True if the 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_ : 1;
+ // True if the symbol has an entry in the GOT section for its
+ // module index.
+ bool has_tls_mod_got_offset_ : 1;
+ // True if the symbol has a pair of entries in the GOT section for its
+ // module index and dtv-relative offset.
+ bool has_tls_pair_got_offset_ : 1;
+ // True if the symbol has an entry in the PLT section.
+ bool has_plt_offset_ : 1;
+ // True if this is a dynamic symbol which needs a special value in
+ // the dynamic symbol table.
+ bool needs_dynsym_value_ : 1;
+ // True if there is a warning for this symbol.
+ 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.
+ bool is_copied_from_dynobj_ : 1;
};
-// The main linker symbol table.
+// 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.
+ template<bool big_endian>
+ void
+ init(const char *name, const char* version, Object* object,
+ const elfcpp::Sym<size, big_endian>&);
+
+ // Initialize fields for an Output_data.
+ void
+ init(const char* name, 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(const char* name, 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(const char* name, Value_type value, Size_type symsize,
+ elfcpp::STT, elfcpp::STB, elfcpp::STV, unsigned char nonvis);
+
+ // Override existing symbol.
+ template<bool big_endian>
+ void
+ override(const elfcpp::Sym<size, big_endian>&, 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 section SHNDX in object OBJ.
+ void
+ add_warning(Symbol_table* symtab, const char* name, Object* obj,
+ unsigned int shndx);
+
+ // For each symbol for which we should give a warning, make a note
+ // on the symbol.
+ void
+ note_warnings(Symbol_table* symtab, const Task*);
+
+ // 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 index of the warning section.
+ unsigned int shndx;
+ // The warning text if we have already loaded it.
+ std::string text;
+
+ Warning_location()
+ : object(NULL), shndx(0), text()
+ { }
+
+ void
+ set(Object* o, unsigned int s)
+ {
+ this->object = o;
+ this->shndx = s;
+ }
+
+ void
+ set_text(const char* t, section_size_type l)
+ { this->text.assign(t, l); }
+ };
+
+ // 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:
- Symbol_table();
+ // 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);
+
+ ~Symbol_table();
+
+ // Add COUNT external symbols from the relocatable object RELOBJ to
+ // the symbol table. SYMS is the symbols, 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.
+ template<int size, bool big_endian>
+ void
+ add_from_relobj(Sized_relobj<size, big_endian>* relobj,
+ const unsigned char* syms, size_t count,
+ const char* sym_names, size_t sym_name_size,
+ typename Sized_relobj<size, big_endian>::Symbols*);
+
+ // 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*>*);
+
+ // 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 Target*, 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 Target*, 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 Target*, 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);
+
+ // Define a set of symbols in output sections.
+ void
+ define_symbols(const Layout*, const Target*, int count,
+ const Define_symbol_in_section*);
+
+ // Define a set of symbols in output segments.
+ void
+ define_symbols(const Layout*, const Target*, int count,
+ const Define_symbol_in_segment*);
+
+ // 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(const Target*, Sized_symbol<size>* sym,
+ Output_data* posd,
+ typename elfcpp::Elf_types<size>::Elf_Addr);
- // Return a pointer to a symbol specified by name.
+ // Look up a symbol.
Symbol*
- lookup(const std::string& name) const;
+ lookup(const char*, const char* version = NULL) const;
- // Return a pointer to a symbol specified by name plus version.
+ // Return the real symbol associated with the forwarder symbol FROM.
Symbol*
- lookup(const std::string& name, const char* version) const;
+ resolve_forwards(const Symbol* from) const;
- Task_token&
- token() const
- { return this->token_; }
+ // Return the sized version of a symbol in this table.
+ template<int size>
+ Sized_symbol<size>*
+ get_sized_symbol(Symbol* ACCEPT_SIZE) const;
+
+ template<int size>
+ const Sized_symbol<size>*
+ get_sized_symbol(const Symbol* ACCEPT_SIZE) const;
+
+ // Return the count of undefined symbols seen.
+ int
+ saw_undefined() const
+ { return this->saw_undefined_; }
+
+ // Allocate the common symbols
+ void
+ allocate_commons(const General_options&, Layout*);
+
+ // Add a warning for symbol NAME in section SHNDX in object OBJ.
+ void
+ add_warning(const char* name, Object* obj, unsigned int shndx)
+ { this->warnings_.add_warning(this, name, obj, shndx); }
+
+ // 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;
+
+ // 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(const Target*, 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. INDEX 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.
+ off_t
+ finalize(const Task*, unsigned int index, off_t off, off_t dynoff,
+ size_t dyn_global_index, size_t dyncount, Stringpool* pool);
+
+ // Write out the global symbols.
+ void
+ write_globals(const Input_objects*, const Stringpool*, const Stringpool*,
+ Output_file*) const;
+
+ // Write out a section symbol. Return the updated offset.
+ void
+ write_section_symbol(const Output_section*, Output_file*, off_t) const;
+
+ // Dump statistical information to stderr.
+ void
+ print_stats() const;
private:
Symbol_table(const Symbol_table&);
Symbol_table& operator=(const Symbol_table&);
- typedef std::pair<std::string, std::string> Symbol_table_key;
+ // 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,
+ const elfcpp::Sym<size, big_endian>& orig_sym);
+
+ // Resolve symbols.
+ template<int size, bool big_endian>
+ void
+ resolve(Sized_symbol<size>* to,
+ const elfcpp::Sym<size, big_endian>& sym,
+ const elfcpp::Sym<size, big_endian>& orig_sym,
+ Object*, const char* version);
+
+ template<int size, bool big_endian>
+ void
+ resolve(Sized_symbol<size>* to, const Sized_symbol<size>* from,
+ const char* version ACCEPT_SIZE_ENDIAN);
+
+ // 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,
+ 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 Target* target, const char** pname,
+ const char** pversion, bool only_if_ref,
+ Sized_symbol<size>** poldsym ACCEPT_SIZE_ENDIAN);
+
+ // Define a symbol in an Output_data, sized version.
+ template<int size>
+ Sized_symbol<size>*
+ do_define_in_output_data(const Target*, 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 Target*, 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 Target*, 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);
- Unordered_map<Symbol_table_key, Symbol<size>*> table_;
- Task_token token_;
+ // Allocate the common symbols, sized version.
+ template<int size>
+ void
+ do_allocate_commons(const General_options&, Layout*);
+
+ // 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(unsigned int, off_t, Stringpool*);
+
+ // 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_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
+ ACCEPT_SIZE_ENDIAN) 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_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 common symbols.
+ typedef std::vector<Symbol*> Commons_type;
+
+ // 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.
+ size_t 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.
+ off_t 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_;
+ // 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_;
};
+// We inline get_sized_symbol for efficiency.
+
+template<int size>
+Sized_symbol<size>*
+Symbol_table::get_sized_symbol(Symbol* sym ACCEPT_SIZE) const
+{
+ gold_assert(size == parameters->get_size());
+ return static_cast<Sized_symbol<size>*>(sym);
+}
+
+template<int size>
+const Sized_symbol<size>*
+Symbol_table::get_sized_symbol(const Symbol* sym ACCEPT_SIZE) const
+{
+ gold_assert(size == parameters->get_size());
+ return static_cast<const Sized_symbol<size>*>(sym);
+}
+
} // End namespace gold.
#endif // !defined(GOLD_SYMTAB_H)
projects / deliverable / binutils-gdb.git / blobdiff