410 lines
12 KiB
C++
410 lines
12 KiB
C++
// reloc.h -- relocate input files for gold -*- C++ -*-
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#ifndef GOLD_RELOC_H
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#define GOLD_RELOC_H
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#include <byteswap.h>
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#include "workqueue.h"
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namespace gold
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{
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class General_options;
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class Relobj;
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class Read_relocs_data;
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class Symbol;
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class Layout;
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template<int size>
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class Sized_symbol;
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template<int size, bool big_endian>
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class Sized_relobj;
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template<int size>
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class Symbol_value;
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template<int sh_type, bool dynamic, int size, bool big_endian>
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class Output_data_reloc;
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// A class to read the relocations for an object file, and then queue
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// up a task to see if they require any GOT/PLT/COPY relocations in
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// the symbol table.
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class Read_relocs : public Task
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{
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public:
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// SYMTAB_LOCK is used to lock the symbol table. BLOCKER should be
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// unblocked when the Scan_relocs task completes.
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Read_relocs(const General_options& options, Symbol_table* symtab,
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Layout* layout, Relobj* object, Task_token* symtab_lock,
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Task_token* blocker)
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: options_(options), symtab_(symtab), layout_(layout), object_(object),
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symtab_lock_(symtab_lock), blocker_(blocker)
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{ }
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// The standard Task methods.
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Is_runnable_type
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is_runnable(Workqueue*);
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Task_locker*
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locks(Workqueue*);
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void
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run(Workqueue*);
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private:
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const General_options& options_;
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Symbol_table* symtab_;
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Layout* layout_;
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Relobj* object_;
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Task_token* symtab_lock_;
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Task_token* blocker_;
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};
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// Scan the relocations for an object to see if they require any
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// GOT/PLT/COPY relocations.
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class Scan_relocs : public Task
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{
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public:
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// SYMTAB_LOCK is used to lock the symbol table. BLOCKER should be
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// unblocked when the task completes.
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Scan_relocs(const General_options& options, Symbol_table* symtab,
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Layout* layout, Relobj* object, Read_relocs_data* rd,
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Task_token* symtab_lock, Task_token* blocker)
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: options_(options), symtab_(symtab), layout_(layout), object_(object),
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rd_(rd), symtab_lock_(symtab_lock), blocker_(blocker)
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{ }
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// The standard Task methods.
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Is_runnable_type
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is_runnable(Workqueue*);
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Task_locker*
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locks(Workqueue*);
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void
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run(Workqueue*);
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private:
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class Scan_relocs_locker;
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const General_options& options_;
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Symbol_table* symtab_;
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Layout* layout_;
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Relobj* object_;
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Read_relocs_data* rd_;
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Task_token* symtab_lock_;
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Task_token* blocker_;
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};
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// A class to perform all the relocations for an object file.
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class Relocate_task : public Task
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{
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public:
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Relocate_task(const General_options& options, const Symbol_table* symtab,
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const Layout* layout, Relobj* object, Output_file* of,
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Task_token* final_blocker)
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: options_(options), symtab_(symtab), layout_(layout), object_(object),
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of_(of), final_blocker_(final_blocker)
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{ }
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// The standard Task methods.
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Is_runnable_type
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is_runnable(Workqueue*);
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Task_locker*
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locks(Workqueue*);
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void
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run(Workqueue*);
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private:
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class Relocate_locker;
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const General_options& options_;
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const Symbol_table* symtab_;
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const Layout* layout_;
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Relobj* object_;
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Output_file* of_;
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Task_token* final_blocker_;
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};
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// Standard relocation routines which are used on many targets. Here
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// SIZE and BIG_ENDIAN refer to the target, not the relocation type.
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template<int size, bool big_endian>
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class Relocate_functions
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{
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private:
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// Do a simple relocation with the addend in the section contents.
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// VALSIZE is the size of the value.
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template<int valsize>
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static inline void
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rel(unsigned char* view,
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typename elfcpp::Swap<valsize, big_endian>::Valtype value)
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{
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typedef typename elfcpp::Swap<valsize, big_endian>::Valtype Valtype;
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Valtype* wv = reinterpret_cast<Valtype*>(view);
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Valtype x = elfcpp::Swap<valsize, big_endian>::readval(wv);
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elfcpp::Swap<valsize, big_endian>::writeval(wv, x + value);
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}
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// Do a simple relocation using a Symbol_value with the addend in
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// the section contents. VALSIZE is the size of the value to
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// relocate.
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template<int valsize>
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static inline void
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rel(unsigned char* view,
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const Sized_relobj<size, big_endian>* object,
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const Symbol_value<size>* psymval)
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{
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typedef typename elfcpp::Swap<valsize, big_endian>::Valtype Valtype;
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Valtype* wv = reinterpret_cast<Valtype*>(view);
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Valtype x = elfcpp::Swap<valsize, big_endian>::readval(wv);
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x = psymval->value(object, x);
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elfcpp::Swap<valsize, big_endian>::writeval(wv, x);
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}
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// Do a simple PC relative relocation with the addend in the section
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// contents. VALSIZE is the size of the value.
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template<int valsize>
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static inline void
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pcrel(unsigned char* view,
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typename elfcpp::Swap<valsize, big_endian>::Valtype value,
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typename elfcpp::Elf_types<size>::Elf_Addr address)
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{
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typedef typename elfcpp::Swap<valsize, big_endian>::Valtype Valtype;
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Valtype* wv = reinterpret_cast<Valtype*>(view);
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Valtype x = elfcpp::Swap<valsize, big_endian>::readval(wv);
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elfcpp::Swap<valsize, big_endian>::writeval(wv, x + value - address);
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}
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// Do a simple PC relative relocation with a Symbol_value with the
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// addend in the section contents. VALSIZE is the size of the
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// value.
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template<int valsize>
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static inline void
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pcrel(unsigned char* view,
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const Sized_relobj<size, big_endian>* object,
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const Symbol_value<size>* psymval,
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typename elfcpp::Elf_types<size>::Elf_Addr address)
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{
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typedef typename elfcpp::Swap<valsize, big_endian>::Valtype Valtype;
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Valtype* wv = reinterpret_cast<Valtype*>(view);
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Valtype x = elfcpp::Swap<valsize, big_endian>::readval(wv);
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x = psymval->value(object, x);
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elfcpp::Swap<valsize, big_endian>::writeval(wv, x - address);
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}
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typedef Relocate_functions<size, big_endian> This;
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public:
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// Do a simple 8-bit REL relocation with the addend in the section
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// contents.
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static inline void
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rel8(unsigned char* view, unsigned char value)
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{ This::template rel<8>(view, value); }
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static inline void
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rel8(unsigned char* view,
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const Sized_relobj<size, big_endian>* object,
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const Symbol_value<size>* psymval)
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{ This::template rel<8>(view, object, psymval); }
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// Do a simple 8-bit PC relative relocation with the addend in the
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// section contents.
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static inline void
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pcrel8(unsigned char* view, unsigned char value,
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typename elfcpp::Elf_types<size>::Elf_Addr address)
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{ This::template pcrel<8>(view, value, address); }
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static inline void
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pcrel8(unsigned char* view,
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const Sized_relobj<size, big_endian>* object,
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const Symbol_value<size>* psymval,
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typename elfcpp::Elf_types<size>::Elf_Addr address)
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{ This::template pcrel<8>(view, object, psymval, address); }
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// Do a simple 16-bit REL relocation with the addend in the section
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// contents.
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static inline void
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rel16(unsigned char* view, elfcpp::Elf_Half value)
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{ This::template rel<16>(view, value); }
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static inline void
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rel16(unsigned char* view,
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const Sized_relobj<size, big_endian>* object,
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const Symbol_value<size>* psymval)
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{ This::template rel<16>(view, object, psymval); }
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// Do a simple 32-bit PC relative REL relocation with the addend in
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// the section contents.
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static inline void
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pcrel16(unsigned char* view, elfcpp::Elf_Word value,
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typename elfcpp::Elf_types<size>::Elf_Addr address)
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{ This::template pcrel<16>(view, value, address); }
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static inline void
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pcrel16(unsigned char* view,
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const Sized_relobj<size, big_endian>* object,
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const Symbol_value<size>* psymval,
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typename elfcpp::Elf_types<size>::Elf_Addr address)
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{ This::template pcrel<16>(view, object, psymval, address); }
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// Do a simple 32-bit REL relocation with the addend in the section
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// contents.
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static inline void
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rel32(unsigned char* view, elfcpp::Elf_Word value)
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{ This::template rel<32>(view, value); }
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static inline void
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rel32(unsigned char* view,
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const Sized_relobj<size, big_endian>* object,
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const Symbol_value<size>* psymval)
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{ This::template rel<32>(view, object, psymval); }
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// Do a simple 32-bit PC relative REL relocation with the addend in
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// the section contents.
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static inline void
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pcrel32(unsigned char* view, elfcpp::Elf_Word value,
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typename elfcpp::Elf_types<size>::Elf_Addr address)
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{ This::template pcrel<32>(view, value, address); }
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static inline void
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pcrel32(unsigned char* view,
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const Sized_relobj<size, big_endian>* object,
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const Symbol_value<size>* psymval,
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typename elfcpp::Elf_types<size>::Elf_Addr address)
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{ This::template pcrel<32>(view, object, psymval, address); }
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// Do a simple 64-bit REL relocation with the addend in the section
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// contents.
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static inline void
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rel64(unsigned char* view, elfcpp::Elf_Xword value)
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{ This::template rel<64>(view, value); }
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static inline void
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rel64(unsigned char* view,
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const Sized_relobj<size, big_endian>* object,
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const Symbol_value<size>* psymval)
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{ This::template rel<64>(view, object, psymval); }
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// Do a simple 64-bit PC relative REL relocation with the addend in
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// the section contents.
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static inline void
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pcrel64(unsigned char* view, elfcpp::Elf_Xword value,
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typename elfcpp::Elf_types<size>::Elf_Addr address)
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{ This::template pcrel<64>(view, value, address); }
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static inline void
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pcrel64(unsigned char* view,
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const Sized_relobj<size, big_endian>* object,
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const Symbol_value<size>* psymval,
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typename elfcpp::Elf_types<size>::Elf_Addr address)
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{ This::template pcrel<64>(view, object, psymval, address); }
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};
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// We try to avoid COPY relocations when possible. A COPY relocation
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// may be required when an executable refers to a variable defined in
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// a shared library. COPY relocations are problematic because they
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// tie the executable to the exact size of the variable in the shared
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// library. We can avoid them if all the references to the variable
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// are in a writeable section. In that case we can simply use dynamic
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// relocations. However, when scanning relocs, we don't know when we
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// see the relocation whether we will be forced to use a COPY
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// relocation or not. So we have to save the relocation during the
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// reloc scanning, and then emit it as a dynamic relocation if
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// necessary. This class implements that. It is used by the target
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// specific code.
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template<int size, bool big_endian>
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class Copy_relocs
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{
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public:
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Copy_relocs()
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: entries_()
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{ }
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// Return whether we need a COPY reloc for a reloc against GSYM,
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// which is being applied to section SHNDX in OBJECT.
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static bool
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need_copy_reloc(const General_options*, Relobj* object, unsigned int shndx,
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Sized_symbol<size>* gsym);
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// Save a Rel against SYM for possible emission later. SHNDX is the
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// index of the section to which the reloc is being applied.
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void
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save(Symbol* sym, Relobj*, unsigned int shndx,
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const elfcpp::Rel<size, big_endian>&);
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// Save a Rela against SYM for possible emission later.
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void
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save(Symbol* sym, Relobj*, unsigned int shndx,
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const elfcpp::Rela<size, big_endian>&);
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// Return whether there are any relocs to emit. This also discards
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// entries which need not be emitted.
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bool
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any_to_emit();
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// Emit relocs for each symbol which did not get a COPY reloc (i.e.,
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// is still defined in the dynamic object).
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template<int sh_type>
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void
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emit(Output_data_reloc<sh_type, true, size, big_endian>*);
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private:
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typedef typename elfcpp::Elf_types<size>::Elf_Addr Address;
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typedef typename elfcpp::Elf_types<size>::Elf_Addr Addend;
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// This POD class holds the entries we are saving.
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class Copy_reloc_entry
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{
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public:
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Copy_reloc_entry(Symbol* sym, unsigned int reloc_type,
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Relobj* relobj, unsigned int shndx,
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Address address, Addend addend)
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: sym_(sym), reloc_type_(reloc_type), relobj_(relobj),
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shndx_(shndx), address_(address), addend_(addend)
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{ }
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// Return whether we should emit this reloc. If we should not
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// emit, we clear it.
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bool
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should_emit();
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// Emit this reloc.
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void
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emit(Output_data_reloc<elfcpp::SHT_REL, true, size, big_endian>*);
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void
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emit(Output_data_reloc<elfcpp::SHT_RELA, true, size, big_endian>*);
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private:
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Symbol* sym_;
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unsigned int reloc_type_;
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Relobj* relobj_;
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unsigned int shndx_;
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Address address_;
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Addend addend_;
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};
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// A list of relocs to be saved.
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typedef std::vector<Copy_reloc_entry> Copy_reloc_entries;
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// The list of relocs we are saving.
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Copy_reloc_entries entries_;
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};
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} // End namespace gold.
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#endif // !defined(GOLD_RELOC_H)
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