old-cross-binutils/gold/target.h
Ian Lance Taylor e291e7b9c9 PR 10287
PR 11063
	* i386.cc (class Target_i386): Change return type of plt_section
	to be non-const.
	(class Output_data_plt_i386): Add tls_desc_rel_ field.
	(Output_data_plt_i386::Output_data_plt_i386): Initialize
	tls_desc_rel_ field.
	(Output_data_plt_i386::rel_tls_desc): New function.
	(Target_i386::rel_tls_desc_section): New function.
	(Target_i386::Scan::local): Rewrite R_386_TLS_GOTDESC handling.
	(Target_i386::Scan::global): For R_386_TLS_GOTDESC put
	R_386_TLS_DESC reloc in rel_tls_desc_section.
	* x86_64.cc (class Target_x86_64): Add tlsdesc_reloc_info_ field.
	Define struct Tlsdesc_info.
	(Target_x86_64::Target_x86_64): Initialize tlsdesc_reloc_info_.
	(Target_x86_64::do_reloc_symbol_index): New function.
	(Target_x86_64::add_tlsdesc_info): New function.
	(class Output_data_plt_x86_64): Add tlsdesc_rel_ field.
	(Output_data_plt_x86_64::Output_data_plt_x86_64): Initialize
	tlsdesc_rel_ field.
	(Output_data_plt_x86_64::rela_plt): Rename from rel_plt.  Change
	all callers.
	(Output_data_plt_x86_64::rela_tlsdesc): New function.
	(Target_x86_64::rela_tlsdesc_section): New function.
	(Target_x86_64::Scan::local): Rewrite R_X86_64_GOTPC32_TLSDESC
	handling.
	(Target_x86_64::Scan::global): For R_X86_64_GOTPC32_TLSDESC put
	(Target_x86_64::do_reloc_addend): New function.
	R_X86_64_TLSDESC reloc in rela_tlsdesc_section.
	* output.h (class Output_reloc) [SHT_REL]: Add new constructor
	declarations.  Define TARGET_CODE.  Add arg field to u1_ union.
	(Output_reloc::type): New function.
	(Output_reloc::is_local_section_symbol): Check for TARGET_CODE.
	(Output_reloc::is_target_specific): New function.
	(Output_reloc::target_arg): New function.
	(class Output_reloc) [SHT_RELA]: Add four new constructors for
	absolute relocs and target specific relocs.
	(class Output_data_reloc) [SHT_REL]: Add add_absolute and
	add_target_specific.
	(class Output_data_reloc) [SHT_RELA]: Likewise.
	* output.cc (Output_reloc::Output_reloc): Add four new versions
	for absolute relocs and target specific relocs.
	(Output_reloc::set_needs_dynsym_index): Add TARGET_CODE case.
	(Output_reloc::get_symbol_index): Likewise.
	(Output_reloc::local_section_offset): Check that local_sym_index_
	is not TARGET_CODE or 0.
	(Output_reloc::symbol_value): Likewise.
	(Output_reloc::write) [SHT_RELA]: Call target for target specific
	reloc.
	* target.h (class Target): Add reloc_symbol_index and reloc_addend
	functions.  Add do_reloc_symbol_index and do_reloc_addend virtual
	functions.
	* layout.cc (add_target_dynamic_tags): Use output section for
	DT_PLTRELSZ and DT_JMPREL.
2010-01-08 19:33:18 +00:00

670 lines
23 KiB
C++

// target.h -- target support for gold -*- C++ -*-
// Copyright 2006, 2007, 2008, 2009 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.
// The abstract class Target is the interface for target specific
// support. It defines abstract methods which each target must
// implement. Typically there will be one target per processor, but
// in some cases it may be necessary to have subclasses.
// For speed and consistency we want to use inline functions to handle
// relocation processing. So besides implementations of the abstract
// methods, each target is expected to define a template
// specialization of the relocation functions.
#ifndef GOLD_TARGET_H
#define GOLD_TARGET_H
#include "elfcpp.h"
#include "options.h"
#include "parameters.h"
#include "debug.h"
namespace gold
{
class Object;
class Relobj;
template<int size, bool big_endian>
class Sized_relobj;
class Relocatable_relocs;
template<int size, bool big_endian>
class Relocate_info;
class Reloc_symbol_changes;
class Symbol;
template<int size>
class Sized_symbol;
class Symbol_table;
class Output_section;
class Input_objects;
// The abstract class for target specific handling.
class Target
{
public:
virtual ~Target()
{ }
// Return the bit size that this target implements. This should
// return 32 or 64.
int
get_size() const
{ return this->pti_->size; }
// Return whether this target is big-endian.
bool
is_big_endian() const
{ return this->pti_->is_big_endian; }
// Machine code to store in e_machine field of ELF header.
elfcpp::EM
machine_code() const
{ return this->pti_->machine_code; }
// Processor specific flags to store in e_flags field of ELF header.
elfcpp::Elf_Word
processor_specific_flags() const
{ return this->processor_specific_flags_; }
// Whether processor specific flags are set at least once.
bool
are_processor_specific_flags_set() const
{ return this->are_processor_specific_flags_set_; }
// Whether this target has a specific make_symbol function.
bool
has_make_symbol() const
{ return this->pti_->has_make_symbol; }
// Whether this target has a specific resolve function.
bool
has_resolve() const
{ return this->pti_->has_resolve; }
// Whether this target has a specific code fill function.
bool
has_code_fill() const
{ return this->pti_->has_code_fill; }
// Return the default name of the dynamic linker.
const char*
dynamic_linker() const
{ return this->pti_->dynamic_linker; }
// Return the default address to use for the text segment.
uint64_t
default_text_segment_address() const
{ return this->pti_->default_text_segment_address; }
// Return the ABI specified page size.
uint64_t
abi_pagesize() const
{
if (parameters->options().max_page_size() > 0)
return parameters->options().max_page_size();
else
return this->pti_->abi_pagesize;
}
// Return the common page size used on actual systems.
uint64_t
common_pagesize() const
{
if (parameters->options().common_page_size() > 0)
return std::min(parameters->options().common_page_size(),
this->abi_pagesize());
else
return std::min(this->pti_->common_pagesize,
this->abi_pagesize());
}
// If we see some object files with .note.GNU-stack sections, and
// some objects files without them, this returns whether we should
// consider the object files without them to imply that the stack
// should be executable.
bool
is_default_stack_executable() const
{ return this->pti_->is_default_stack_executable; }
// Return a character which may appear as a prefix for a wrap
// symbol. If this character appears, we strip it when checking for
// wrapping and add it back when forming the final symbol name.
// This should be '\0' if not special prefix is required, which is
// the normal case.
char
wrap_char() const
{ return this->pti_->wrap_char; }
// Return the special section index which indicates a small common
// symbol. This will return SHN_UNDEF if there are no small common
// symbols.
elfcpp::Elf_Half
small_common_shndx() const
{ return this->pti_->small_common_shndx; }
// Return values to add to the section flags for the section holding
// small common symbols.
elfcpp::Elf_Xword
small_common_section_flags() const
{
gold_assert(this->pti_->small_common_shndx != elfcpp::SHN_UNDEF);
return this->pti_->small_common_section_flags;
}
// Return the special section index which indicates a large common
// symbol. This will return SHN_UNDEF if there are no large common
// symbols.
elfcpp::Elf_Half
large_common_shndx() const
{ return this->pti_->large_common_shndx; }
// Return values to add to the section flags for the section holding
// large common symbols.
elfcpp::Elf_Xword
large_common_section_flags() const
{
gold_assert(this->pti_->large_common_shndx != elfcpp::SHN_UNDEF);
return this->pti_->large_common_section_flags;
}
// This hook is called when an output section is created.
void
new_output_section(Output_section* os) const
{ this->do_new_output_section(os); }
// This is called to tell the target to complete any sections it is
// handling. After this all sections must have their final size.
void
finalize_sections(Layout* layout, const Input_objects* input_objects,
Symbol_table* symtab)
{ return this->do_finalize_sections(layout, input_objects, symtab); }
// Return the value to use for a global symbol which needs a special
// value in the dynamic symbol table. This will only be called if
// the backend first calls symbol->set_needs_dynsym_value().
uint64_t
dynsym_value(const Symbol* sym) const
{ return this->do_dynsym_value(sym); }
// Return a string to use to fill out a code section. This is
// basically one or more NOPS which must fill out the specified
// length in bytes.
std::string
code_fill(section_size_type length) const
{ return this->do_code_fill(length); }
// Return whether SYM is known to be defined by the ABI. This is
// used to avoid inappropriate warnings about undefined symbols.
bool
is_defined_by_abi(const Symbol* sym) const
{ return this->do_is_defined_by_abi(sym); }
// Adjust the output file header before it is written out. VIEW
// points to the header in external form. LEN is the length.
void
adjust_elf_header(unsigned char* view, int len) const
{ return this->do_adjust_elf_header(view, len); }
// Return whether NAME is a local label name. This is used to implement the
// --discard-locals options.
bool
is_local_label_name(const char* name) const
{ return this->do_is_local_label_name(name); }
// Get the symbol index to use for a target specific reloc.
unsigned int
reloc_symbol_index(void* arg, unsigned int type) const
{ return this->do_reloc_symbol_index(arg, type); }
// Get the addend to use for a target specific reloc.
uint64_t
reloc_addend(void* arg, unsigned int type, uint64_t addend) const
{ return this->do_reloc_addend(arg, type, addend); }
// A function starts at OFFSET in section SHNDX in OBJECT. That
// function was compiled with -fsplit-stack, but it refers to a
// function which was compiled without -fsplit-stack. VIEW is a
// modifiable view of the section; VIEW_SIZE is the size of the
// view. The target has to adjust the function so that it allocates
// enough stack.
void
calls_non_split(Relobj* object, unsigned int shndx,
section_offset_type fnoffset, section_size_type fnsize,
unsigned char* view, section_size_type view_size,
std::string* from, std::string* to) const
{
this->do_calls_non_split(object, shndx, fnoffset, fnsize, view, view_size,
from, to);
}
// Make an ELF object.
template<int size, bool big_endian>
Object*
make_elf_object(const std::string& name, Input_file* input_file,
off_t offset, const elfcpp::Ehdr<size, big_endian>& ehdr)
{ return this->do_make_elf_object(name, input_file, offset, ehdr); }
// Make an output section.
Output_section*
make_output_section(const char* name, elfcpp::Elf_Word type,
elfcpp::Elf_Xword flags)
{ return this->do_make_output_section(name, type, flags); }
// Return true if target wants to perform relaxation.
bool
may_relax() const
{
// Run the dummy relaxation pass twice if relaxation debugging is enabled.
if (is_debugging_enabled(DEBUG_RELAXATION))
return true;
return this->do_may_relax();
}
// Perform a relaxation pass. Return true if layout may be changed.
bool
relax(int pass, const Input_objects* input_objects, Symbol_table* symtab,
Layout* layout)
{
// Run the dummy relaxation pass twice if relaxation debugging is enabled.
if (is_debugging_enabled(DEBUG_RELAXATION))
return pass < 2;
return this->do_relax(pass, input_objects, symtab, layout);
}
// Return the target-specific name of attributes section. This is
// NULL if a target does not use attributes section or if it uses
// the default section name ".gnu.attributes".
const char*
attributes_section() const
{ return this->pti_->attributes_section; }
// Return the vendor name of vendor attributes.
const char*
attributes_vendor() const
{ return this->pti_->attributes_vendor; }
// Whether a section called NAME is an attribute section.
bool
is_attributes_section(const char* name) const
{
return ((this->pti_->attributes_section != NULL
&& strcmp(name, this->pti_->attributes_section) == 0)
|| strcmp(name, ".gnu.attributes") == 0);
}
// Return a bit mask of argument types for attribute with TAG.
int
attribute_arg_type(int tag) const
{ return this->do_attribute_arg_type(tag); }
// Return the attribute tag of the position NUM in the list of fixed
// attributes. Normally there is no reordering and
// attributes_order(NUM) == NUM.
int
attributes_order(int num) const
{ return this->do_attributes_order(num); }
protected:
// This struct holds the constant information for a child class. We
// use a struct to avoid the overhead of virtual function calls for
// simple information.
struct Target_info
{
// Address size (32 or 64).
int size;
// Whether the target is big endian.
bool is_big_endian;
// The code to store in the e_machine field of the ELF header.
elfcpp::EM machine_code;
// Whether this target has a specific make_symbol function.
bool has_make_symbol;
// Whether this target has a specific resolve function.
bool has_resolve;
// Whether this target has a specific code fill function.
bool has_code_fill;
// Whether an object file with no .note.GNU-stack sections implies
// that the stack should be executable.
bool is_default_stack_executable;
// Prefix character to strip when checking for wrapping.
char wrap_char;
// The default dynamic linker name.
const char* dynamic_linker;
// The default text segment address.
uint64_t default_text_segment_address;
// The ABI specified page size.
uint64_t abi_pagesize;
// The common page size used by actual implementations.
uint64_t common_pagesize;
// The special section index for small common symbols; SHN_UNDEF
// if none.
elfcpp::Elf_Half small_common_shndx;
// The special section index for large common symbols; SHN_UNDEF
// if none.
elfcpp::Elf_Half large_common_shndx;
// Section flags for small common section.
elfcpp::Elf_Xword small_common_section_flags;
// Section flags for large common section.
elfcpp::Elf_Xword large_common_section_flags;
// Name of attributes section if it is not ".gnu.attributes".
const char* attributes_section;
// Vendor name of vendor attributes.
const char* attributes_vendor;
};
Target(const Target_info* pti)
: pti_(pti), processor_specific_flags_(0),
are_processor_specific_flags_set_(false)
{ }
// Virtual function which may be implemented by the child class.
virtual void
do_new_output_section(Output_section*) const
{ }
// Virtual function which may be implemented by the child class.
virtual void
do_finalize_sections(Layout*, const Input_objects*, Symbol_table*)
{ }
// Virtual function which may be implemented by the child class.
virtual uint64_t
do_dynsym_value(const Symbol*) const
{ gold_unreachable(); }
// Virtual function which must be implemented by the child class if
// needed.
virtual std::string
do_code_fill(section_size_type) const
{ gold_unreachable(); }
// Virtual function which may be implemented by the child class.
virtual bool
do_is_defined_by_abi(const Symbol*) const
{ return false; }
// Adjust the output file header before it is written out. VIEW
// points to the header in external form. LEN is the length, and
// will be one of the values of elfcpp::Elf_sizes<size>::ehdr_size.
// By default, we do nothing.
virtual void
do_adjust_elf_header(unsigned char*, int) const
{ }
// Virtual function which may be overriden by the child class.
virtual bool
do_is_local_label_name(const char*) const;
// Virtual function that must be overridden by a target which uses
// target specific relocations.
virtual unsigned int
do_reloc_symbol_index(void*, unsigned int) const
{ gold_unreachable(); }
// Virtual function that must be overidden by a target which uses
// target specific relocations.
virtual uint64_t
do_reloc_addend(void*, unsigned int, uint64_t) const
{ gold_unreachable(); }
// Virtual function which may be overridden by the child class.
virtual void
do_calls_non_split(Relobj* object, unsigned int, section_offset_type,
section_size_type, unsigned char*, section_size_type,
std::string*, std::string*) const;
// make_elf_object hooks. There are four versions of these for
// different address sizes and endianities.
// Set processor specific flags.
void
set_processor_specific_flags(elfcpp::Elf_Word flags)
{
this->processor_specific_flags_ = flags;
this->are_processor_specific_flags_set_ = true;
}
#ifdef HAVE_TARGET_32_LITTLE
// Virtual functions which may be overriden by the child class.
virtual Object*
do_make_elf_object(const std::string&, Input_file*, off_t,
const elfcpp::Ehdr<32, false>&);
#endif
#ifdef HAVE_TARGET_32_BIG
// Virtual functions which may be overriden by the child class.
virtual Object*
do_make_elf_object(const std::string&, Input_file*, off_t,
const elfcpp::Ehdr<32, true>&);
#endif
#ifdef HAVE_TARGET_64_LITTLE
// Virtual functions which may be overriden by the child class.
virtual Object*
do_make_elf_object(const std::string&, Input_file*, off_t,
const elfcpp::Ehdr<64, false>& ehdr);
#endif
#ifdef HAVE_TARGET_64_BIG
// Virtual functions which may be overriden by the child class.
virtual Object*
do_make_elf_object(const std::string& name, Input_file* input_file,
off_t offset, const elfcpp::Ehdr<64, true>& ehdr);
#endif
// Virtual functions which may be overriden by the child class.
virtual Output_section*
do_make_output_section(const char* name, elfcpp::Elf_Word type,
elfcpp::Elf_Xword flags);
// Virtual function which may be overriden by the child class.
virtual bool
do_may_relax() const
{ return parameters->options().relax(); }
// Virtual function which may be overriden by the child class.
virtual bool
do_relax(int, const Input_objects*, Symbol_table*, Layout*)
{ return false; }
// A function for targets to call. Return whether BYTES/LEN matches
// VIEW/VIEW_SIZE at OFFSET.
bool
match_view(const unsigned char* view, section_size_type view_size,
section_offset_type offset, const char* bytes, size_t len) const;
// Set the contents of a VIEW/VIEW_SIZE to nops starting at OFFSET
// for LEN bytes.
void
set_view_to_nop(unsigned char* view, section_size_type view_size,
section_offset_type offset, size_t len) const;
// This must be overriden by the child class if it has target-specific
// attributes subsection in the attribute section.
virtual int
do_attribute_arg_type(int) const
{ gold_unreachable(); }
// This may be overridden by the child class.
virtual int
do_attributes_order(int num) const
{ return num; }
private:
// The implementations of the four do_make_elf_object virtual functions are
// almost identical except for their sizes and endianity. We use a template.
// for their implementations.
template<int size, bool big_endian>
inline Object*
do_make_elf_object_implementation(const std::string&, Input_file*, off_t,
const elfcpp::Ehdr<size, big_endian>&);
Target(const Target&);
Target& operator=(const Target&);
// The target information.
const Target_info* pti_;
// Processor-specific flags.
elfcpp::Elf_Word processor_specific_flags_;
// Whether the processor-specific flags are set at least once.
bool are_processor_specific_flags_set_;
};
// The abstract class for a specific size and endianness of target.
// Each actual target implementation class should derive from an
// instantiation of Sized_target.
template<int size, bool big_endian>
class Sized_target : public Target
{
public:
// Make a new symbol table entry for the target. This should be
// overridden by a target which needs additional information in the
// symbol table. This will only be called if has_make_symbol()
// returns true.
virtual Sized_symbol<size>*
make_symbol() const
{ gold_unreachable(); }
// Resolve a symbol for the target. This should be overridden by a
// target which needs to take special action. TO is the
// pre-existing symbol. SYM is the new symbol, seen in OBJECT.
// VERSION is the version of SYM. This will only be called if
// has_resolve() returns true.
virtual void
resolve(Symbol*, const elfcpp::Sym<size, big_endian>&, Object*,
const char*)
{ gold_unreachable(); }
// Process the relocs for a section, and record information of the
// mapping from source to destination sections. This mapping is later
// used to determine unreferenced garbage sections. This procedure is
// only called during garbage collection.
virtual void
gc_process_relocs(Symbol_table* symtab,
Layout* layout,
Sized_relobj<size, big_endian>* object,
unsigned int data_shndx,
unsigned int sh_type,
const unsigned char* prelocs,
size_t reloc_count,
Output_section* output_section,
bool needs_special_offset_handling,
size_t local_symbol_count,
const unsigned char* plocal_symbols) = 0;
// Scan the relocs for a section, and record any information
// required for the symbol. SYMTAB is the symbol table. OBJECT is
// the object in which the section appears. DATA_SHNDX is the
// section index that these relocs apply to. SH_TYPE is the type of
// the relocation section, SHT_REL or SHT_RELA. PRELOCS points to
// the relocation data. RELOC_COUNT is the number of relocs.
// LOCAL_SYMBOL_COUNT is the number of local symbols.
// OUTPUT_SECTION is the output section.
// NEEDS_SPECIAL_OFFSET_HANDLING is true if offsets to the output
// sections are not mapped as usual. PLOCAL_SYMBOLS points to the
// local symbol data from OBJECT. GLOBAL_SYMBOLS is the array of
// pointers to the global symbol table from OBJECT.
virtual void
scan_relocs(Symbol_table* symtab,
Layout* layout,
Sized_relobj<size, big_endian>* object,
unsigned int data_shndx,
unsigned int sh_type,
const unsigned char* prelocs,
size_t reloc_count,
Output_section* output_section,
bool needs_special_offset_handling,
size_t local_symbol_count,
const unsigned char* plocal_symbols) = 0;
// Relocate section data. SH_TYPE is the type of the relocation
// section, SHT_REL or SHT_RELA. PRELOCS points to the relocation
// information. RELOC_COUNT is the number of relocs.
// OUTPUT_SECTION is the output section.
// NEEDS_SPECIAL_OFFSET_HANDLING is true if offsets must be mapped
// to correspond to the output section. VIEW is a view into the
// output file holding the section contents, VIEW_ADDRESS is the
// virtual address of the view, and VIEW_SIZE is the size of the
// view. If NEEDS_SPECIAL_OFFSET_HANDLING is true, the VIEW_xx
// parameters refer to the complete output section data, not just
// the input section data.
virtual void
relocate_section(const Relocate_info<size, big_endian>*,
unsigned int sh_type,
const unsigned char* prelocs,
size_t reloc_count,
Output_section* output_section,
bool needs_special_offset_handling,
unsigned char* view,
typename elfcpp::Elf_types<size>::Elf_Addr view_address,
section_size_type view_size,
const Reloc_symbol_changes*) = 0;
// Scan the relocs during a relocatable link. The parameters are
// like scan_relocs, with an additional Relocatable_relocs
// parameter, used to record the disposition of the relocs.
virtual void
scan_relocatable_relocs(Symbol_table* symtab,
Layout* layout,
Sized_relobj<size, big_endian>* object,
unsigned int data_shndx,
unsigned int sh_type,
const unsigned char* prelocs,
size_t reloc_count,
Output_section* output_section,
bool needs_special_offset_handling,
size_t local_symbol_count,
const unsigned char* plocal_symbols,
Relocatable_relocs*) = 0;
// Relocate a section during a relocatable link. The parameters are
// like relocate_section, with additional parameters for the view of
// the output reloc section.
virtual void
relocate_for_relocatable(const Relocate_info<size, big_endian>*,
unsigned int sh_type,
const unsigned char* prelocs,
size_t reloc_count,
Output_section* output_section,
off_t offset_in_output_section,
const Relocatable_relocs*,
unsigned char* view,
typename elfcpp::Elf_types<size>::Elf_Addr
view_address,
section_size_type view_size,
unsigned char* reloc_view,
section_size_type reloc_view_size) = 0;
protected:
Sized_target(const Target::Target_info* pti)
: Target(pti)
{
gold_assert(pti->size == size);
gold_assert(pti->is_big_endian ? big_endian : !big_endian);
}
};
} // End namespace gold.
#endif // !defined(GOLD_TARGET_H)