binutils-gdb/gold/target.h

1186 lines
41 KiB
C++

// target.h -- target support for gold -*- C++ -*-
// Copyright (C) 2006-2020 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 "stringpool.h"
#include "debug.h"
namespace gold
{
class Object;
class Relobj;
template<int size, bool big_endian>
class Sized_relobj;
template<int size, bool big_endian>
class Sized_relobj_file;
class Relocatable_relocs;
template<int size, bool big_endian>
struct Relocate_info;
class Reloc_symbol_changes;
class Symbol;
template<int size>
class Sized_symbol;
class Symbol_table;
class Output_data;
class Output_data_got_base;
class Output_section;
class Input_objects;
class Task;
struct Symbol_location;
class Versions;
// 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.
// If a -z max-page-size argument has set the ABI page size
// to a value larger than the default starting address,
// bump the starting address up to the page size, to avoid
// misaligning the text segment in the file.
uint64_t
default_text_segment_address() const
{
uint64_t addr = this->pti_->default_text_segment_address;
uint64_t pagesize = this->abi_pagesize();
if (addr < pagesize)
addr = pagesize;
return addr;
}
// 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());
}
// Return whether PF_X segments must contain nothing but the contents of
// SHF_EXECINSTR sections (no non-executable data, no headers).
bool
isolate_execinstr() const
{ return this->pti_->isolate_execinstr; }
uint64_t
rosegment_gap() const
{ return this->pti_->rosegment_gap; }
// 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)
{ return this->do_adjust_elf_header(view, len); }
// Return address and size to plug into eh_frame FDEs associated with a PLT.
void
plt_fde_location(const Output_data* plt, unsigned char* oview,
uint64_t* address, off_t* len) const
{ return this->do_plt_fde_location(plt, oview, address, 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); }
// Return the PLT address to use for a global symbol.
uint64_t
plt_address_for_global(const Symbol* sym) const
{ return this->do_plt_address_for_global(sym); }
// Return the PLT address to use for a local symbol.
uint64_t
plt_address_for_local(const Relobj* object, unsigned int symndx) const
{ return this->do_plt_address_for_local(object, symndx); }
// Return the offset to use for the GOT_INDX'th got entry which is
// for a local tls symbol specified by OBJECT, SYMNDX.
int64_t
tls_offset_for_local(const Relobj* object,
unsigned int symndx,
unsigned int got_indx) const
{ return do_tls_offset_for_local(object, symndx, got_indx); }
// Return the offset to use for the GOT_INDX'th got entry which is
// for global tls symbol GSYM.
int64_t
tls_offset_for_global(Symbol* gsym, unsigned int got_indx) const
{ return do_tls_offset_for_global(gsym, got_indx); }
// For targets that use function descriptors, if LOC is the location
// of a function, modify it to point at the function entry location.
void
function_location(Symbol_location* loc) const
{ return do_function_location(loc); }
// Return whether this target can use relocation types to determine
// if a function's address is taken.
bool
can_check_for_function_pointers() const
{ return this->do_can_check_for_function_pointers(); }
// Return whether a relocation to a merged section can be processed
// to retrieve the contents.
bool
can_icf_inline_merge_sections () const
{ return this->pti_->can_icf_inline_merge_sections; }
// Whether a section called SECTION_NAME may have function pointers to
// sections not eligible for safe ICF folding.
virtual bool
section_may_have_icf_unsafe_pointers(const char* section_name) const
{ return this->do_section_may_have_icf_unsafe_pointers(section_name); }
// Return the base to use for the PC value in an FDE when it is
// encoded using DW_EH_PE_datarel. This does not appear to be
// documented anywhere, but it is target specific. Any use of
// DW_EH_PE_datarel in gcc requires defining a special macro
// (ASM_MAYBE_OUTPUT_ENCODED_ADDR_RTX) to output the value.
uint64_t
ehframe_datarel_base() const
{ return this->do_ehframe_datarel_base(); }
// Return true if a reference to SYM from a reloc at *PRELOC
// means that the current function may call an object compiled
// without -fsplit-stack. SYM is known to be defined in an object
// compiled without -fsplit-stack.
bool
is_call_to_non_split(const Symbol* sym, const unsigned char* preloc,
const unsigned char* view,
section_size_type view_size) const
{ return this->do_is_call_to_non_split(sym, preloc, view, view_size); }
// 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,
const unsigned char* prelocs, size_t reloc_count,
unsigned char* view, section_size_type view_size,
std::string* from, std::string* to) const
{
this->do_calls_non_split(object, shndx, fnoffset, fnsize,
prelocs, reloc_count, 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, const Task* task)
{
// 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, task);
}
// 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); }
// When a target is selected as the default target, we call this method,
// which may be used for expensive, target-specific initialization.
void
select_as_default_target()
{ this->do_select_as_default_target(); }
// Return the value to store in the EI_OSABI field in the ELF
// header.
elfcpp::ELFOSABI
osabi() const
{ return this->osabi_; }
// Set the value to store in the EI_OSABI field in the ELF header.
void
set_osabi(elfcpp::ELFOSABI osabi)
{ this->osabi_ = osabi; }
// Define target-specific standard symbols.
void
define_standard_symbols(Symbol_table* symtab, Layout* layout)
{ this->do_define_standard_symbols(symtab, layout); }
// Return the output section name to use given an input section
// name, or NULL if no target specific name mapping is required.
// Set *PLEN to the length of the name if returning non-NULL.
const char*
output_section_name(const Relobj* relobj,
const char* name,
size_t* plen) const
{ return this->do_output_section_name(relobj, name, plen); }
// Add any special sections for this symbol to the gc work list.
void
gc_mark_symbol(Symbol_table* symtab, Symbol* sym) const
{ this->do_gc_mark_symbol(symtab, sym); }
// Return the name of the entry point symbol.
const char*
entry_symbol_name() const
{ return this->pti_->entry_symbol_name; }
// Return the size in bits of SHT_HASH entry.
int
hash_entry_size() const
{ return this->pti_->hash_entry_size; }
// Return the section type to use for unwind sections.
unsigned int
unwind_section_type() const
{ return this->pti_->unwind_section_type; }
// Whether the target has a custom set_dynsym_indexes method.
bool
has_custom_set_dynsym_indexes() const
{ return this->do_has_custom_set_dynsym_indexes(); }
// Custom set_dynsym_indexes method for a target.
unsigned int
set_dynsym_indexes(std::vector<Symbol*>* dyn_symbols, unsigned int index,
std::vector<Symbol*>* syms, Stringpool* dynpool,
Versions* versions, Symbol_table* symtab) const
{
return this->do_set_dynsym_indexes(dyn_symbols, index, syms, dynpool,
versions, symtab);
}
// Get the custom dynamic tag value.
unsigned int
dynamic_tag_custom_value(elfcpp::DT tag) const
{ return this->do_dynamic_tag_custom_value(tag); }
// Adjust the value written to the dynamic symbol table.
void
adjust_dyn_symbol(const Symbol* sym, unsigned char* view) const
{ this->do_adjust_dyn_symbol(sym, view); }
// Return whether to include the section in the link.
bool
should_include_section(elfcpp::Elf_Word sh_type) const
{ return this->do_should_include_section(sh_type); }
// Finalize the target-specific properties in the .note.gnu.property section.
void
finalize_gnu_properties(Layout* layout) const
{ this->do_finalize_gnu_properties(layout); }
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;
// Whether a relocation to a merged section can be processed to
// retrieve the contents.
bool can_icf_inline_merge_sections;
// 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;
// Whether PF_X segments must contain nothing but the contents of
// SHF_EXECINSTR sections (no non-executable data, no headers).
bool isolate_execinstr;
// If nonzero, distance from the text segment to the read-only segment.
uint64_t rosegment_gap;
// 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;
// Name of the main entry point to the program.
const char* entry_symbol_name;
// Size (in bits) of SHT_HASH entry. Always equal to 32, except for
// 64-bit S/390.
const int hash_entry_size;
// Processor-specific section type for ".eh_frame" (unwind) sections.
// SHT_PROGBITS if there is no special section type.
const unsigned int unwind_section_type;
};
Target(const Target_info* pti)
: pti_(pti), processor_specific_flags_(0),
are_processor_specific_flags_set_(false), osabi_(elfcpp::ELFOSABI_NONE)
{ }
// 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 set the EI_OSABI field if requested (in
// Sized_target).
virtual void
do_adjust_elf_header(unsigned char*, int) = 0;
// Return address and size to plug into eh_frame FDEs associated with a PLT.
virtual void
do_plt_fde_location(const Output_data* plt, unsigned char* oview,
uint64_t* address, off_t* len) const;
// Virtual function which may be overridden 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 overridden by a target which uses
// target specific relocations.
virtual uint64_t
do_reloc_addend(void*, unsigned int, uint64_t) const
{ gold_unreachable(); }
// Virtual functions that must be overridden by a target that uses
// STT_GNU_IFUNC symbols.
virtual uint64_t
do_plt_address_for_global(const Symbol*) const
{ gold_unreachable(); }
virtual uint64_t
do_plt_address_for_local(const Relobj*, unsigned int) const
{ gold_unreachable(); }
virtual int64_t
do_tls_offset_for_local(const Relobj*, unsigned int, unsigned int) const
{ gold_unreachable(); }
virtual int64_t
do_tls_offset_for_global(Symbol*, unsigned int) const
{ gold_unreachable(); }
virtual void
do_function_location(Symbol_location*) const = 0;
// Virtual function which may be overriden by the child class.
virtual bool
do_can_check_for_function_pointers() const
{ return false; }
// Virtual function which may be overridden by the child class. We
// recognize some default sections for which we don't care whether
// they have function pointers.
virtual bool
do_section_may_have_icf_unsafe_pointers(const char* section_name) const
{
// We recognize sections for normal vtables, construction vtables and
// EH frames.
return (!is_prefix_of(".rodata._ZTV", section_name)
&& !is_prefix_of(".data.rel.ro._ZTV", section_name)
&& !is_prefix_of(".rodata._ZTC", section_name)
&& !is_prefix_of(".data.rel.ro._ZTC", section_name)
&& !is_prefix_of(".eh_frame", section_name));
}
virtual uint64_t
do_ehframe_datarel_base() const
{ gold_unreachable(); }
// Virtual function which may be overridden by the child class. The
// default implementation is that any function not defined by the
// ABI is a call to a non-split function.
virtual bool
do_is_call_to_non_split(const Symbol* sym, const unsigned char*,
const unsigned char*, section_size_type) const;
// 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, const unsigned char*, size_t,
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 endianness.
// 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 overridden 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 overridden 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 overridden 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 overridden 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 overridden 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 overridden by the child class.
virtual bool
do_may_relax() const
{ return parameters->options().relax(); }
// Virtual function which may be overridden by the child class.
virtual bool
do_relax(int, const Input_objects*, Symbol_table*, Layout*, const Task*)
{ 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 overridden 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; }
// This may be overridden by the child class.
virtual void
do_select_as_default_target()
{ }
// This may be overridden by the child class.
virtual void
do_define_standard_symbols(Symbol_table*, Layout*)
{ }
// This may be overridden by the child class.
virtual const char*
do_output_section_name(const Relobj*, const char*, size_t*) const
{ return NULL; }
// This may be overridden by the child class.
virtual void
do_gc_mark_symbol(Symbol_table*, Symbol*) const
{ }
// This may be overridden by the child class.
virtual bool
do_has_custom_set_dynsym_indexes() const
{ return false; }
// This may be overridden by the child class.
virtual unsigned int
do_set_dynsym_indexes(std::vector<Symbol*>*, unsigned int,
std::vector<Symbol*>*, Stringpool*, Versions*,
Symbol_table*) const
{ gold_unreachable(); }
// This may be overridden by the child class.
virtual unsigned int
do_dynamic_tag_custom_value(elfcpp::DT) const
{ gold_unreachable(); }
// This may be overridden by the child class.
virtual void
do_adjust_dyn_symbol(const Symbol*, unsigned char*) const
{ }
// This may be overridden by the child class.
virtual bool
do_should_include_section(elfcpp::Elf_Word) const
{ return true; }
// Finalize the target-specific properties in the .note.gnu.property section.
virtual void
do_finalize_gnu_properties(Layout*) const
{ }
private:
// The implementations of the four do_make_elf_object virtual functions are
// almost identical except for their sizes and endianness. 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_;
// If not ELFOSABI_NONE, the value to put in the EI_OSABI field of
// the ELF header. This is handled at this level because it is
// OS-specific rather than processor-specific.
elfcpp::ELFOSABI osabi_;
};
// 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 char*, elfcpp::STT, Object*, unsigned int, uint64_t)
{ 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 bool
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_file<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_file<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_file<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;
// Scan the relocs for --emit-relocs. The parameters are
// like scan_relocatable_relocs.
virtual void
emit_relocs_scan(Symbol_table* symtab,
Layout* layout,
Sized_relobj_file<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_syms,
Relocatable_relocs* rr) = 0;
// Emit relocations for a section during a relocatable link, and for
// --emit-relocs. The parameters are like relocate_section, with
// additional parameters for the view of the output reloc section.
virtual void
relocate_relocs(const Relocate_info<size, big_endian>*,
unsigned int sh_type,
const unsigned char* prelocs,
size_t reloc_count,
Output_section* output_section,
typename elfcpp::Elf_types<size>::Elf_Off
offset_in_output_section,
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;
// Perform target-specific processing in a relocatable link. This is
// only used if we use the relocation strategy RELOC_SPECIAL.
// RELINFO points to a Relocation_info structure. SH_TYPE is the relocation
// section type. PRELOC_IN points to the original relocation. RELNUM is
// the index number of the relocation in the relocation section.
// OUTPUT_SECTION is the output section to which the relocation is applied.
// OFFSET_IN_OUTPUT_SECTION is the offset of the relocation input section
// within the output section. VIEW points to the output view of the
// output section. VIEW_ADDRESS is output address of the view. VIEW_SIZE
// is the size of the output view and PRELOC_OUT points to the new
// relocation in the output object.
//
// A target only needs to override this if the generic code in
// target-reloc.h cannot handle some relocation types.
virtual void
relocate_special_relocatable(const Relocate_info<size, big_endian>*
/*relinfo */,
unsigned int /* sh_type */,
const unsigned char* /* preloc_in */,
size_t /* relnum */,
Output_section* /* output_section */,
typename elfcpp::Elf_types<size>::Elf_Off
/* offset_in_output_section */,
unsigned char* /* view */,
typename elfcpp::Elf_types<size>::Elf_Addr
/* view_address */,
section_size_type /* view_size */,
unsigned char* /* preloc_out*/)
{ gold_unreachable(); }
// Return the number of entries in the GOT. This is only used for
// laying out the incremental link info sections. A target needs
// to implement this to support incremental linking.
virtual unsigned int
got_entry_count() const
{ gold_unreachable(); }
// Return the number of entries in the PLT. This is only used for
// laying out the incremental link info sections. A target needs
// to implement this to support incremental linking.
virtual unsigned int
plt_entry_count() const
{ gold_unreachable(); }
// Return the offset of the first non-reserved PLT entry. This is
// only used for laying out the incremental link info sections.
// A target needs to implement this to support incremental linking.
virtual unsigned int
first_plt_entry_offset() const
{ gold_unreachable(); }
// Return the size of each PLT entry. This is only used for
// laying out the incremental link info sections. A target needs
// to implement this to support incremental linking.
virtual unsigned int
plt_entry_size() const
{ gold_unreachable(); }
// Return the size of each GOT entry. This is only used for
// laying out the incremental link info sections. A target needs
// to implement this if its GOT size is different.
virtual unsigned int
got_entry_size() const
{ return size / 8; }
// Create the GOT and PLT sections for an incremental update.
// A target needs to implement this to support incremental linking.
virtual Output_data_got_base*
init_got_plt_for_update(Symbol_table*,
Layout*,
unsigned int /* got_count */,
unsigned int /* plt_count */)
{ gold_unreachable(); }
// Reserve a GOT entry for a local symbol, and regenerate any
// necessary dynamic relocations.
virtual void
reserve_local_got_entry(unsigned int /* got_index */,
Sized_relobj<size, big_endian>* /* obj */,
unsigned int /* r_sym */,
unsigned int /* got_type */)
{ gold_unreachable(); }
// Reserve a GOT entry for a global symbol, and regenerate any
// necessary dynamic relocations.
virtual void
reserve_global_got_entry(unsigned int /* got_index */, Symbol* /* gsym */,
unsigned int /* got_type */)
{ gold_unreachable(); }
// Register an existing PLT entry for a global symbol.
// A target needs to implement this to support incremental linking.
virtual void
register_global_plt_entry(Symbol_table*, Layout*,
unsigned int /* plt_index */,
Symbol*)
{ gold_unreachable(); }
// Force a COPY relocation for a given symbol.
// A target needs to implement this to support incremental linking.
virtual void
emit_copy_reloc(Symbol_table*, Symbol*, Output_section*, off_t)
{ gold_unreachable(); }
// Apply an incremental relocation.
virtual void
apply_relocation(const Relocate_info<size, big_endian>* /* relinfo */,
typename elfcpp::Elf_types<size>::Elf_Addr /* r_offset */,
unsigned int /* r_type */,
typename elfcpp::Elf_types<size>::Elf_Swxword /* r_addend */,
const Symbol* /* gsym */,
unsigned char* /* view */,
typename elfcpp::Elf_types<size>::Elf_Addr /* address */,
section_size_type /* view_size */)
{ gold_unreachable(); }
// Handle target specific gc actions when adding a gc reference from
// SRC_OBJ, SRC_SHNDX to a location specified by DST_OBJ, DST_SHNDX
// and DST_OFF.
void
gc_add_reference(Symbol_table* symtab,
Relobj* src_obj,
unsigned int src_shndx,
Relobj* dst_obj,
unsigned int dst_shndx,
typename elfcpp::Elf_types<size>::Elf_Addr dst_off) const
{
this->do_gc_add_reference(symtab, src_obj, src_shndx,
dst_obj, dst_shndx, dst_off);
}
// Return the r_sym field from a relocation.
// Most targets can use the default version of this routine,
// but some targets have a non-standard r_info field, and will
// need to provide a target-specific version.
virtual unsigned int
get_r_sym(const unsigned char* preloc) const
{
// Since REL and RELA relocs share the same structure through
// the r_info field, we can just use REL here.
elfcpp::Rel<size, big_endian> rel(preloc);
return elfcpp::elf_r_sym<size>(rel.get_r_info());
}
// Record a target-specific program property in the .note.gnu.property
// section.
virtual void
record_gnu_property(unsigned int, unsigned int, size_t,
const unsigned char*, const Object*)
{ }
// Merge the target-specific program properties from the current object.
virtual void
merge_gnu_properties(const Object*)
{ }
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);
}
// Set the EI_OSABI field if requested.
virtual void
do_adjust_elf_header(unsigned char*, int);
// Handle target specific gc actions when adding a gc reference.
virtual void
do_gc_add_reference(Symbol_table*, Relobj*, unsigned int,
Relobj*, unsigned int,
typename elfcpp::Elf_types<size>::Elf_Addr) const
{ }
virtual void
do_function_location(Symbol_location*) const
{ }
};
} // End namespace gold.
#endif // !defined(GOLD_TARGET_H)