binutils-gdb/gold/output.h

933 lines
24 KiB
C++

// output.h -- manage the output file for gold -*- C++ -*-
#ifndef GOLD_OUTPUT_H
#define GOLD_OUTPUT_H
#include <cassert>
#include <list>
#include <vector>
#include "elfcpp.h"
#include "layout.h"
namespace gold
{
class General_options;
class Object;
class Output_file;
template<int size, bool big_endian>
class Sized_target;
// An abtract class for data which has to go into the output file.
class Output_data
{
public:
explicit Output_data(off_t data_size = 0)
: address_(0), data_size_(data_size), offset_(-1)
{ }
virtual
~Output_data();
// Return the address. This is only valid after Layout::finalize is
// finished.
uint64_t
address() const
{ return this->address_; }
// Return the size of the data. This must be valid after
// Layout::finalize calls set_address, but need not be valid before
// then.
off_t
data_size() const
{ return this->data_size_; }
// Return the file offset. This is only valid after
// Layout::finalize is finished.
off_t
offset() const
{ return this->offset_; }
// Return the required alignment.
uint64_t
addralign() const
{ return this->do_addralign(); }
// Return whether this is an Output_section.
bool
is_section() const
{ return this->do_is_section(); }
// Return whether this is an Output_section of the specified type.
bool
is_section_type(elfcpp::Elf_Word stt) const
{ return this->do_is_section_type(stt); }
// Return whether this is an Output_section with the specified flag
// set.
bool
is_section_flag_set(elfcpp::Elf_Xword shf) const
{ return this->do_is_section_flag_set(shf); }
// Return the output section index, if there is an output section.
unsigned int
out_shndx() const
{ return this->do_out_shndx(); }
// Set the output section index, if this is an output section.
void
set_out_shndx(unsigned int shndx)
{ this->do_set_out_shndx(shndx); }
// Set the address and file offset of this data. This is called
// during Layout::finalize.
void
set_address(uint64_t addr, off_t off);
// Write the data to the output file. This is called after
// Layout::finalize is complete.
void
write(Output_file* file)
{ this->do_write(file); }
protected:
// Functions that child classes may or in some cases must implement.
// Write the data to the output file.
virtual void
do_write(Output_file*) = 0;
// Return the required alignment.
virtual uint64_t
do_addralign() const = 0;
// Return whether this is an Output_section.
virtual bool
do_is_section() const
{ return false; }
// Return whether this is an Output_section of the specified type.
// This only needs to be implement by Output_section.
virtual bool
do_is_section_type(elfcpp::Elf_Word) const
{ return false; }
// Return whether this is an Output_section with the specific flag
// set. This only needs to be implemented by Output_section.
virtual bool
do_is_section_flag_set(elfcpp::Elf_Xword) const
{ return false; }
// Return the output section index, if there is an output section.
virtual unsigned int
do_out_shndx() const
{ abort(); }
// Set the output section index, if this is an output section.
virtual void
do_set_out_shndx(unsigned int)
{ abort(); }
// Set the address and file offset of the data. This only needs to
// be implemented if the child needs to know.
virtual void
do_set_address(uint64_t, off_t)
{ }
// Functions that child classes may call.
// Set the size of the data.
void
set_data_size(off_t data_size)
{ this->data_size_ = data_size; }
// Return default alignment for a size--32 or 64.
static uint64_t
default_alignment(int size);
private:
Output_data(const Output_data&);
Output_data& operator=(const Output_data&);
// Memory address in file (not always meaningful).
uint64_t address_;
// Size of data in file.
off_t data_size_;
// Offset within file.
off_t offset_;
};
// A simple case of Output_data in which we have constant data to
// output.
class Output_data_const : public Output_data
{
public:
Output_data_const(const std::string& data, uint64_t addralign)
: Output_data(data.size()), data_(data), addralign_(addralign)
{ }
Output_data_const(const char* p, off_t len, uint64_t addralign)
: Output_data(len), data_(p, len), addralign_(addralign)
{ }
// Write the data to the file.
void
do_write(Output_file* output);
// Return the required alignment.
uint64_t
do_addralign() const
{ return this->addralign_; }
private:
std::string data_;
uint64_t addralign_;
};
// Output the section headers.
class Output_section_headers : public Output_data
{
public:
Output_section_headers(int size,
bool big_endian,
const Layout::Segment_list&,
const Layout::Section_list&,
const Stringpool*);
// Write the data to the file.
void
do_write(Output_file*);
// Return the required alignment.
uint64_t
do_addralign() const
{ return Output_data::default_alignment(this->size_); }
private:
// Write the data to the file with the right size and endianness.
template<int size, bool big_endian>
void
do_sized_write(Output_file*);
int size_;
bool big_endian_;
const Layout::Segment_list& segment_list_;
const Layout::Section_list& section_list_;
const Stringpool* secnamepool_;
};
// Output the segment headers.
class Output_segment_headers : public Output_data
{
public:
Output_segment_headers(int size, bool big_endian,
const Layout::Segment_list& segment_list);
// Write the data to the file.
void
do_write(Output_file*);
// Return the required alignment.
uint64_t
do_addralign() const
{ return Output_data::default_alignment(this->size_); }
private:
// Write the data to the file with the right size and endianness.
template<int size, bool big_endian>
void
do_sized_write(Output_file*);
int size_;
bool big_endian_;
const Layout::Segment_list& segment_list_;
};
// Output the ELF file header.
class Output_file_header : public Output_data
{
public:
Output_file_header(int size,
bool big_endian,
const General_options&,
const Target*,
const Symbol_table*,
const Output_segment_headers*);
// Add information about the section headers. We lay out the ELF
// file header before we create the section headers.
void set_section_info(const Output_section_headers*,
const Output_section* shstrtab);
// Write the data to the file.
void
do_write(Output_file*);
// Return the required alignment.
uint64_t
do_addralign() const
{ return Output_data::default_alignment(this->size_); }
// Set the address and offset--we only implement this for error
// checking.
void
do_set_address(uint64_t, off_t off) const
{ assert(off == 0); }
private:
// Write the data to the file with the right size and endianness.
template<int size, bool big_endian>
void
do_sized_write(Output_file*);
int size_;
bool big_endian_;
const General_options& options_;
const Target* target_;
const Symbol_table* symtab_;
const Output_segment_headers* segment_header_;
const Output_section_headers* section_header_;
const Output_section* shstrtab_;
};
// Output sections are mainly comprised of input sections. However,
// there are cases where we have data to write out which is not in an
// input section. Output_section_data is used in such cases. This is
// an abstract base class.
class Output_section_data : public Output_data
{
public:
Output_section_data(off_t data_size, uint64_t addralign)
: Output_data(data_size), output_section_(NULL), addralign_(addralign)
{ }
Output_section_data(uint64_t addralign)
: Output_data(0), output_section_(NULL), addralign_(addralign)
{ }
// Record the output section.
void
set_output_section(Output_section* os)
{
assert(this->output_section_ == NULL);
this->output_section_ = os;
}
protected:
// The child class must implement do_write.
// Return the required alignment.
uint64_t
do_addralign() const
{ return this->addralign_; }
// Return the section index of the output section.
unsigned int
do_out_shndx() const;
private:
// The output section for this section.
const Output_section* output_section_;
// The required alignment.
uint64_t addralign_;
};
// Output_section_common is used to handle the common symbols. This
// is quite simple.
class Output_section_common : public Output_section_data
{
public:
Output_section_common(uint64_t addralign)
: Output_section_data(addralign)
{ }
// Set the size.
void
set_common_size(off_t common_size)
{ this->set_data_size(common_size); }
// Write out the data--there is nothing to do, as common symbols are
// always zero and are stored in the BSS.
void
do_write(Output_file*)
{ }
};
// Output_section_got is used to manage a GOT. Each entry in the GOT
// is for one symbol--either a global symbol or a local symbol in an
// object. The target specific code adds entries to the GOT as
// needed. The GOT code is then responsible for writing out the data
// and for generating relocs as required.
template<int size, bool big_endian>
class Output_section_got : public Output_section_data
{
public:
typedef typename elfcpp::Elf_types<size>::Elf_Addr Valtype;
Output_section_got()
: Output_section_data(Output_data::default_alignment(size)),
entries_()
{ }
// Add an entry for a global symbol to the GOT. This returns the
// offset of the new entry from the start of the GOT.
unsigned int
add_global(Symbol* gsym)
{
this->entries_.push_back(Got_entry(gsym));
this->set_got_size();
return this->last_got_offset();
}
// Add an entry for a local symbol to the GOT. This returns the
// offset of the new entry from the start of the GOT.
unsigned int
add_local(Object* object, unsigned int sym_index)
{
this->entries_.push_back(Got_entry(object, sym_index));
this->set_got_size();
return this->last_got_offset();
}
// Add a constant to the GOT. This returns the offset of the new
// entry from the start of the GOT.
unsigned int
add_constant(Valtype constant)
{
this->entries_.push_back(Got_entry(constant));
this->set_got_size();
return this->last_got_offset();
}
// Write out the GOT table.
void
do_write(Output_file*);
private:
// This POD class holds a single GOT entry.
class Got_entry
{
public:
// Create a zero entry.
Got_entry()
: local_sym_index_(CONSTANT_CODE)
{ this->u_.constant = 0; }
// Create a global symbol entry.
Got_entry(Symbol* gsym)
: local_sym_index_(GSYM_CODE)
{ this->u_.gsym = gsym; }
// Create a local symbol entry.
Got_entry(Object* object, unsigned int local_sym_index)
: local_sym_index_(local_sym_index)
{
assert(local_sym_index != GSYM_CODE
&& local_sym_index != CONSTANT_CODE);
this->u_.object = object;
}
// Create a constant entry. The constant is a host value--it will
// be swapped, if necessary, when it is written out.
Got_entry(Valtype constant)
: local_sym_index_(CONSTANT_CODE)
{ this->u_.constant = constant; }
// Write the GOT entry to an output view.
void
write(unsigned char* pov) const;
private:
enum
{
GSYM_CODE = -1U,
CONSTANT_CODE = -2U
};
union
{
// For a local symbol, the object.
Object* object;
// For a global symbol, the symbol.
Symbol* gsym;
// For a constant, the constant.
Valtype constant;
} u_;
// For a local symbol, the local symbol index. This is -1U for a
// global symbol, or -2U for a constant.
unsigned int local_sym_index_;
};
typedef std::vector<Got_entry> Got_entries;
// Return the offset into the GOT of GOT entry I.
unsigned int
got_offset(unsigned int i) const
{ return i * (size / 8); }
// Return the offset into the GOT of the last entry added.
unsigned int
last_got_offset() const
{ return this->got_offset(this->entries_.size() - 1); }
// Set the size of the section.
void
set_got_size()
{ this->set_data_size(this->got_offset(this->entries_.size())); }
// The list of GOT entries.
Got_entries entries_;
};
// An output section. We don't expect to have too many output
// sections, so we don't bother to do a template on the size.
class Output_section : public Output_data
{
public:
// Create an output section, giving the name, type, and flags.
Output_section(const char* name, elfcpp::Elf_Word, elfcpp::Elf_Xword,
bool may_add_data);
virtual ~Output_section();
// Add a new input section SHNDX, named NAME, with header SHDR, from
// object OBJECT. Return the offset within the output section.
template<int size, bool big_endian>
off_t
add_input_section(Relobj* object, unsigned int shndx, const char *name,
const elfcpp::Shdr<size, big_endian>& shdr);
// Add generated data ODATA to this output section.
virtual void
add_output_section_data(Output_section_data* posd);
// Return the section name.
const char*
name() const
{ return this->name_; }
// Return the section type.
elfcpp::Elf_Word
type() const
{ return this->type_; }
// Return the section flags.
elfcpp::Elf_Xword
flags() const
{ return this->flags_; }
// Return the section index in the output file.
unsigned int
do_out_shndx() const
{ return this->out_shndx_; }
// Set the output section index.
void
do_set_out_shndx(unsigned int shndx)
{ this->out_shndx_ = shndx; }
// Set the entsize field.
void
set_entsize(uint64_t v)
{ this->entsize_ = v; }
// Set the link field.
void
set_link(unsigned int v)
{ this->link_ = v; }
// Set the info field.
void
set_info(unsigned int v)
{ this->info_ = v; }
// Set the addralign field.
void
set_addralign(uint64_t v)
{ this->addralign_ = v; }
// Set the address of the Output_section. For a typical
// Output_section, there is nothing to do, but if there are any
// Output_section_data objects we need to set the final addresses
// here.
void
do_set_address(uint64_t, off_t);
// Write the data to the file. For a typical Output_section, this
// does nothing: the data is written out by calling Object::Relocate
// on each input object. But if there are any Output_section_data
// objects we do need to write them out here.
virtual void
do_write(Output_file*);
// Return the address alignment--function required by parent class.
uint64_t
do_addralign() const
{ return this->addralign_; }
// Return whether this is an Output_section.
bool
do_is_section() const
{ return true; }
// Return whether this is a section of the specified type.
bool
do_is_section_type(elfcpp::Elf_Word type) const
{ return this->type_ == type; }
// Return whether the specified section flag is set.
bool
do_is_section_flag_set(elfcpp::Elf_Xword flag) const
{ return (this->flags_ & flag) != 0; }
// Write the section header into *OPHDR.
template<int size, bool big_endian>
void
write_header(const Stringpool*, elfcpp::Shdr_write<size, big_endian>*) const;
private:
// In some cases we need to keep a list of the input sections
// associated with this output section. We only need the list if we
// might have to change the offsets of the input section within the
// output section after we add the input section. The ordinary
// input sections will be written out when we process the object
// file, and as such we don't need to track them here. We do need
// to track Output_section_data objects here. We store instances of
// this structure in a std::vector, so it must be a POD. There can
// be many instances of this structure, so we use a union to save
// some space.
class Input_section
{
public:
Input_section()
: shndx_(0), p2align_(0), data_size_(0)
{ this->u_.object = NULL; }
Input_section(Relobj* object, unsigned int shndx, off_t data_size,
uint64_t addralign)
: shndx_(shndx),
p2align_(ffsll(static_cast<long long>(addralign))),
data_size_(data_size)
{
assert(shndx != -1U);
this->u_.object = object;
}
Input_section(Output_section_data* posd)
: shndx_(-1U),
p2align_(ffsll(static_cast<long long>(posd->addralign()))),
data_size_(0)
{ this->u_.posd = posd; }
// The required alignment.
uint64_t
addralign() const
{ return static_cast<uint64_t>(1) << this->p2align_; }
// Return the required size.
off_t
data_size() const;
// Set the address and file offset. This is called during
// Layout::finalize. SECOFF is the file offset of the enclosing
// section.
void
set_address(uint64_t addr, off_t off, off_t secoff);
// Write out the data. This does nothing for an input section.
void
write(Output_file*);
private:
// Whether this is an input section.
bool
is_input_section() const
{ return this->shndx_ != -1U; }
// For an ordinary input section, this is the section index in
// the input file. For an Output_section_data, this is -1U.
unsigned int shndx_;
// The required alignment, stored as a power of 2.
unsigned int p2align_;
// For an ordinary input section, the section size.
off_t data_size_;
union
{
// If shndx_ != -1U, this points to the object which holds the
// input section.
Relobj* object;
// If shndx_ == -1U, this is the data to write out.
Output_section_data* posd;
} u_;
};
typedef std::vector<Input_section> Input_section_list;
// Most of these fields are only valid after layout.
// The name of the section. This will point into a Stringpool.
const char* name_;
// The section address is in the parent class.
// The section alignment.
uint64_t addralign_;
// The section entry size.
uint64_t entsize_;
// The file offset is in the parent class.
// The section link field.
unsigned int link_;
// The section info field.
unsigned int info_;
// The section type.
elfcpp::Elf_Word type_;
// The section flags.
elfcpp::Elf_Xword flags_;
// The section index.
unsigned int out_shndx_;
// The input sections. This will be empty in cases where we don't
// need to keep track of them.
Input_section_list input_sections_;
// The offset of the first entry in input_sections_.
off_t first_input_offset_;
// Whether we permit adding data.
bool may_add_data_;
};
// A special Output_section which represents the symbol table
// (SHT_SYMTAB). The actual data is written out by
// Symbol_table::write_globals.
class Output_section_symtab : public Output_section
{
public:
Output_section_symtab(const char* name, off_t size);
// The data is written out by Symbol_table::write_globals. We don't
// do anything here.
void
do_write(Output_file*)
{ }
// We don't expect to see any input sections or data here.
void
add_output_section_data(Output_section_data*)
{ abort(); }
};
// A special Output_section which holds a string table.
class Output_section_strtab : public Output_section
{
public:
Output_section_strtab(const char* name, Stringpool* contents);
// Write out the data.
void
do_write(Output_file*);
// We don't expect to see any input sections or data here.
void
add_output_section_data(Output_section_data*)
{ abort(); }
private:
Stringpool* contents_;
};
// An output segment. PT_LOAD segments are built from collections of
// output sections. Other segments typically point within PT_LOAD
// segments, and are built directly as needed.
class Output_segment
{
public:
// Create an output segment, specifying the type and flags.
Output_segment(elfcpp::Elf_Word, elfcpp::Elf_Word);
// Return the virtual address.
uint64_t
vaddr() const
{ return this->vaddr_; }
// Return the physical address.
uint64_t
paddr() const
{ return this->paddr_; }
// Return the segment type.
elfcpp::Elf_Word
type() const
{ return this->type_; }
// Return the segment flags.
elfcpp::Elf_Word
flags() const
{ return this->flags_; }
// Return the memory size.
uint64_t
memsz() const
{ return this->memsz_; }
// Return the file size.
off_t
filesz() const
{ return this->filesz_; }
// Return the maximum alignment of the Output_data.
uint64_t
addralign();
// Add an Output_section to this segment.
void
add_output_section(Output_section*, elfcpp::Elf_Word seg_flags);
// Add an Output_data (which is not an Output_section) to the start
// of this segment.
void
add_initial_output_data(Output_data*);
// Set the address of the segment to ADDR and the offset to *POFF
// (aligned if necessary), and set the addresses and offsets of all
// contained output sections accordingly. Set the section indexes
// of all contained output sections starting with *PSHNDX. Return
// the address of the immediately following segment. Update *POFF
// and *PSHNDX. This should only be called for a PT_LOAD segment.
uint64_t
set_section_addresses(uint64_t addr, off_t* poff, unsigned int* pshndx);
// Set the offset of this segment based on the section. This should
// only be called for a non-PT_LOAD segment.
void
set_offset();
// Return the number of output sections.
unsigned int
output_section_count() const;
// Write the segment header into *OPHDR.
template<int size, bool big_endian>
void
write_header(elfcpp::Phdr_write<size, big_endian>*);
// Write the section headers of associated sections into V.
template<int size, bool big_endian>
unsigned char*
write_section_headers(const Stringpool*,
unsigned char* v,
unsigned int* pshndx ACCEPT_SIZE_ENDIAN) const;
private:
Output_segment(const Output_segment&);
Output_segment& operator=(const Output_segment&);
typedef std::list<Output_data*> Output_data_list;
// Find the maximum alignment in an Output_data_list.
static uint64_t
maximum_alignment(const Output_data_list*);
// Set the section addresses in an Output_data_list.
uint64_t
set_section_list_addresses(Output_data_list*, uint64_t addr, off_t* poff,
unsigned int* pshndx);
// Return the number of Output_sections in an Output_data_list.
unsigned int
output_section_count_list(const Output_data_list*) const;
// Write the section headers in the list into V.
template<int size, bool big_endian>
unsigned char*
write_section_headers_list(const Stringpool*, const Output_data_list*,
unsigned char* v,
unsigned int* pshdx ACCEPT_SIZE_ENDIAN) const;
// The list of output data with contents attached to this segment.
Output_data_list output_data_;
// The list of output data without contents attached to this segment.
Output_data_list output_bss_;
// The segment virtual address.
uint64_t vaddr_;
// The segment physical address.
uint64_t paddr_;
// The size of the segment in memory.
uint64_t memsz_;
// The segment alignment.
uint64_t align_;
// The offset of the segment data within the file.
off_t offset_;
// The size of the segment data in the file.
off_t filesz_;
// The segment type;
elfcpp::Elf_Word type_;
// The segment flags.
elfcpp::Elf_Word flags_;
// Whether we have set align_.
bool is_align_known_;
};
// This class represents the output file.
class Output_file
{
public:
Output_file(const General_options& options);
// Open the output file. FILE_SIZE is the final size of the file.
void
open(off_t file_size);
// Close the output file and make sure there are no error.
void
close();
// We currently always use mmap which makes the view handling quite
// simple. In the future we may support other approaches.
// Write data to the output file.
void
write(off_t offset, const void* data, off_t len)
{ memcpy(this->base_ + offset, data, len); }
// Get a buffer to use to write to the file, given the offset into
// the file and the size.
unsigned char*
get_output_view(off_t start, off_t size)
{
assert(start >= 0 && size >= 0 && start + size <= this->file_size_);
return this->base_ + start;
}
// VIEW must have been returned by get_output_view. Write the
// buffer to the file, passing in the offset and the size.
void
write_output_view(off_t, off_t, unsigned char*)
{ }
private:
// General options.
const General_options& options_;
// File name.
const char* name_;
// File descriptor.
int o_;
// File size.
off_t file_size_;
// Base of file mapped into memory.
unsigned char* base_;
};
} // End namespace gold.
#endif // !defined(GOLD_OUTPUT_H)