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binutils-gdb/gold/x86_64.cc

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// x86_64.cc -- x86_64 target support for gold.
// Copyright (C) 2006-2015 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.
#include "gold.h"
#include <cstring>
#include "elfcpp.h"
#include "dwarf.h"
#include "parameters.h"
#include "reloc.h"
#include "x86_64.h"
#include "object.h"
#include "symtab.h"
#include "layout.h"
#include "output.h"
#include "copy-relocs.h"
#include "target.h"
#include "target-reloc.h"
#include "target-select.h"
#include "tls.h"
#include "freebsd.h"
#include "nacl.h"
#include "gc.h"
#include "icf.h"
namespace
{
using namespace gold;
// A class to handle the .got.plt section.
class Output_data_got_plt_x86_64 : public Output_section_data_build
{
public:
Output_data_got_plt_x86_64(Layout* layout)
: Output_section_data_build(8),
layout_(layout)
{ }
Output_data_got_plt_x86_64(Layout* layout, off_t data_size)
: Output_section_data_build(data_size, 8),
layout_(layout)
{ }
protected:
// Write out the PLT data.
void
do_write(Output_file*);
// Write to a map file.
void
do_print_to_mapfile(Mapfile* mapfile) const
{ mapfile->print_output_data(this, "** GOT PLT"); }
private:
// A pointer to the Layout class, so that we can find the .dynamic
// section when we write out the GOT PLT section.
Layout* layout_;
};
// A class to handle the PLT data.
// This is an abstract base class that handles most of the linker details
// but does not know the actual contents of PLT entries. The derived
// classes below fill in those details.
template<int size>
class Output_data_plt_x86_64 : public Output_section_data
{
public:
typedef Output_data_reloc<elfcpp::SHT_RELA, true, size, false> Reloc_section;
Output_data_plt_x86_64(Layout* layout, uint64_t addralign,
Output_data_got<64, false>* got,
Output_data_got_plt_x86_64* got_plt,
Output_data_space* got_irelative)
: Output_section_data(addralign), tlsdesc_rel_(NULL),
irelative_rel_(NULL), got_(got), got_plt_(got_plt),
got_irelative_(got_irelative), count_(0), irelative_count_(0),
tlsdesc_got_offset_(-1U), free_list_()
{ this->init(layout); }
Output_data_plt_x86_64(Layout* layout, uint64_t plt_entry_size,
Output_data_got<64, false>* got,
Output_data_got_plt_x86_64* got_plt,
Output_data_space* got_irelative,
unsigned int plt_count)
: Output_section_data((plt_count + 1) * plt_entry_size,
plt_entry_size, false),
tlsdesc_rel_(NULL), irelative_rel_(NULL), got_(got),
got_plt_(got_plt), got_irelative_(got_irelative), count_(plt_count),
irelative_count_(0), tlsdesc_got_offset_(-1U), free_list_()
{
this->init(layout);
// Initialize the free list and reserve the first entry.
this->free_list_.init((plt_count + 1) * plt_entry_size, false);
this->free_list_.remove(0, plt_entry_size);
}
// Initialize the PLT section.
void
init(Layout* layout);
// Add an entry to the PLT.
void
add_entry(Symbol_table*, Layout*, Symbol* gsym);
// Add an entry to the PLT for a local STT_GNU_IFUNC symbol.
unsigned int
add_local_ifunc_entry(Symbol_table* symtab, Layout*,
Sized_relobj_file<size, false>* relobj,
unsigned int local_sym_index);
// Add the relocation for a PLT entry.
void
add_relocation(Symbol_table*, Layout*, Symbol* gsym,
unsigned int got_offset);
// Add the reserved TLSDESC_PLT entry to the PLT.
void
reserve_tlsdesc_entry(unsigned int got_offset)
{ this->tlsdesc_got_offset_ = got_offset; }
// Return true if a TLSDESC_PLT entry has been reserved.
bool
has_tlsdesc_entry() const
{ return this->tlsdesc_got_offset_ != -1U; }
// Return the GOT offset for the reserved TLSDESC_PLT entry.
unsigned int
get_tlsdesc_got_offset() const
{ return this->tlsdesc_got_offset_; }
// Return the offset of the reserved TLSDESC_PLT entry.
unsigned int
get_tlsdesc_plt_offset() const
{
return ((this->count_ + this->irelative_count_ + 1)
* this->get_plt_entry_size());
}
// Return the .rela.plt section data.
Reloc_section*
rela_plt()
{ return this->rel_; }
// Return where the TLSDESC relocations should go.
Reloc_section*
rela_tlsdesc(Layout*);
// Return where the IRELATIVE relocations should go in the PLT
// relocations.
Reloc_section*
rela_irelative(Symbol_table*, Layout*);
// Return whether we created a section for IRELATIVE relocations.
bool
has_irelative_section() const
{ return this->irelative_rel_ != NULL; }
// Return the number of PLT entries.
unsigned int
entry_count() const
{ return this->count_ + this->irelative_count_; }
// Return the offset of the first non-reserved PLT entry.
unsigned int
first_plt_entry_offset()
{ return this->get_plt_entry_size(); }
// Return the size of a PLT entry.
unsigned int
get_plt_entry_size() const
{ return this->do_get_plt_entry_size(); }
// Reserve a slot in the PLT for an existing symbol in an incremental update.
void
reserve_slot(unsigned int plt_index)
{
this->free_list_.remove((plt_index + 1) * this->get_plt_entry_size(),
(plt_index + 2) * this->get_plt_entry_size());
}
// Return the PLT address to use for a global symbol.
uint64_t
address_for_global(const Symbol*);
// Return the PLT address to use for a local symbol.
uint64_t
address_for_local(const Relobj*, unsigned int symndx);
// Add .eh_frame information for the PLT.
void
add_eh_frame(Layout* layout)
{ this->do_add_eh_frame(layout); }
protected:
// Fill in the first PLT entry.
void
fill_first_plt_entry(unsigned char* pov,
typename elfcpp::Elf_types<size>::Elf_Addr got_address,
typename elfcpp::Elf_types<size>::Elf_Addr plt_address)
{ this->do_fill_first_plt_entry(pov, got_address, plt_address); }
// Fill in a normal PLT entry. Returns the offset into the entry that
// should be the initial GOT slot value.
unsigned int
fill_plt_entry(unsigned char* pov,
typename elfcpp::Elf_types<size>::Elf_Addr got_address,
typename elfcpp::Elf_types<size>::Elf_Addr plt_address,
unsigned int got_offset,
unsigned int plt_offset,
unsigned int plt_index)
{
return this->do_fill_plt_entry(pov, got_address, plt_address,
got_offset, plt_offset, plt_index);
}
// Fill in the reserved TLSDESC PLT entry.
void
fill_tlsdesc_entry(unsigned char* pov,
typename elfcpp::Elf_types<size>::Elf_Addr got_address,
typename elfcpp::Elf_types<size>::Elf_Addr plt_address,
typename elfcpp::Elf_types<size>::Elf_Addr got_base,
unsigned int tlsdesc_got_offset,
unsigned int plt_offset)
{
this->do_fill_tlsdesc_entry(pov, got_address, plt_address, got_base,
tlsdesc_got_offset, plt_offset);
}
virtual unsigned int
do_get_plt_entry_size() const = 0;
virtual void
do_fill_first_plt_entry(unsigned char* pov,
typename elfcpp::Elf_types<size>::Elf_Addr got_addr,
typename elfcpp::Elf_types<size>::Elf_Addr plt_addr)
= 0;
virtual unsigned int
do_fill_plt_entry(unsigned char* pov,
typename elfcpp::Elf_types<size>::Elf_Addr got_address,
typename elfcpp::Elf_types<size>::Elf_Addr plt_address,
unsigned int got_offset,
unsigned int plt_offset,
unsigned int plt_index) = 0;
virtual void
do_fill_tlsdesc_entry(unsigned char* pov,
typename elfcpp::Elf_types<size>::Elf_Addr got_address,
typename elfcpp::Elf_types<size>::Elf_Addr plt_address,
typename elfcpp::Elf_types<size>::Elf_Addr got_base,
unsigned int tlsdesc_got_offset,
unsigned int plt_offset) = 0;
virtual void
do_add_eh_frame(Layout* layout) = 0;
void
do_adjust_output_section(Output_section* os);
// Write to a map file.
void
do_print_to_mapfile(Mapfile* mapfile) const
{ mapfile->print_output_data(this, _("** PLT")); }
// The CIE of the .eh_frame unwind information for the PLT.
static const int plt_eh_frame_cie_size = 16;
static const unsigned char plt_eh_frame_cie[plt_eh_frame_cie_size];
private:
// Set the final size.
void
set_final_data_size();
// Write out the PLT data.
void
do_write(Output_file*);
// The reloc section.
Reloc_section* rel_;
// The TLSDESC relocs, if necessary. These must follow the regular
// PLT relocs.
Reloc_section* tlsdesc_rel_;
// The IRELATIVE relocs, if necessary. These must follow the
// regular PLT relocations and the TLSDESC relocations.
Reloc_section* irelative_rel_;
// The .got section.
Output_data_got<64, false>* got_;
// The .got.plt section.
Output_data_got_plt_x86_64* got_plt_;
// The part of the .got.plt section used for IRELATIVE relocs.
Output_data_space* got_irelative_;
// The number of PLT entries.
unsigned int count_;
// Number of PLT entries with R_X86_64_IRELATIVE relocs. These
// follow the regular PLT entries.
unsigned int irelative_count_;
// Offset of the reserved TLSDESC_GOT entry when needed.
unsigned int tlsdesc_got_offset_;
// List of available regions within the section, for incremental
// update links.
Free_list free_list_;
};
template<int size>
class Output_data_plt_x86_64_standard : public Output_data_plt_x86_64<size>
{
public:
Output_data_plt_x86_64_standard(Layout* layout,
Output_data_got<64, false>* got,
Output_data_got_plt_x86_64* got_plt,
Output_data_space* got_irelative)
: Output_data_plt_x86_64<size>(layout, plt_entry_size,
got, got_plt, got_irelative)
{ }
Output_data_plt_x86_64_standard(Layout* layout,
Output_data_got<64, false>* got,
Output_data_got_plt_x86_64* got_plt,
Output_data_space* got_irelative,
unsigned int plt_count)
: Output_data_plt_x86_64<size>(layout, plt_entry_size,
got, got_plt, got_irelative,
plt_count)
{ }
protected:
virtual unsigned int
do_get_plt_entry_size() const
{ return plt_entry_size; }
virtual void
do_add_eh_frame(Layout* layout)
{
layout->add_eh_frame_for_plt(this,
this->plt_eh_frame_cie,
this->plt_eh_frame_cie_size,
plt_eh_frame_fde,
plt_eh_frame_fde_size);
}
virtual void
do_fill_first_plt_entry(unsigned char* pov,
typename elfcpp::Elf_types<size>::Elf_Addr got_addr,
typename elfcpp::Elf_types<size>::Elf_Addr plt_addr);
virtual unsigned int
do_fill_plt_entry(unsigned char* pov,
typename elfcpp::Elf_types<size>::Elf_Addr got_address,
typename elfcpp::Elf_types<size>::Elf_Addr plt_address,
unsigned int got_offset,
unsigned int plt_offset,
unsigned int plt_index);
virtual void
do_fill_tlsdesc_entry(unsigned char* pov,
typename elfcpp::Elf_types<size>::Elf_Addr got_address,
typename elfcpp::Elf_types<size>::Elf_Addr plt_address,
typename elfcpp::Elf_types<size>::Elf_Addr got_base,
unsigned int tlsdesc_got_offset,
unsigned int plt_offset);
private:
// The size of an entry in the PLT.
static const int plt_entry_size = 16;
// The first entry in the PLT.
// From the AMD64 ABI: "Unlike Intel386 ABI, this ABI uses the same
// procedure linkage table for both programs and shared objects."
static const unsigned char first_plt_entry[plt_entry_size];
// Other entries in the PLT for an executable.
static const unsigned char plt_entry[plt_entry_size];
// The reserved TLSDESC entry in the PLT for an executable.
static const unsigned char tlsdesc_plt_entry[plt_entry_size];
// The .eh_frame unwind information for the PLT.
static const int plt_eh_frame_fde_size = 32;
static const unsigned char plt_eh_frame_fde[plt_eh_frame_fde_size];
};
// The x86_64 target class.
// See the ABI at
// http://www.x86-64.org/documentation/abi.pdf
// TLS info comes from
// http://people.redhat.com/drepper/tls.pdf
// http://www.lsd.ic.unicamp.br/~oliva/writeups/TLS/RFC-TLSDESC-x86.txt
template<int size>
class Target_x86_64 : public Sized_target<size, false>
{
public:
// In the x86_64 ABI (p 68), it says "The AMD64 ABI architectures
// uses only Elf64_Rela relocation entries with explicit addends."
typedef Output_data_reloc<elfcpp::SHT_RELA, true, size, false> Reloc_section;
Target_x86_64(const Target::Target_info* info = &x86_64_info)
: Sized_target<size, false>(info),
got_(NULL), plt_(NULL), got_plt_(NULL), got_irelative_(NULL),
got_tlsdesc_(NULL), global_offset_table_(NULL), rela_dyn_(NULL),
rela_irelative_(NULL), copy_relocs_(elfcpp::R_X86_64_COPY),
got_mod_index_offset_(-1U), tlsdesc_reloc_info_(),
tls_base_symbol_defined_(false)
{ }
// Hook for a new output section.
void
do_new_output_section(Output_section*) const;
// Scan the relocations to look for symbol adjustments.
void
gc_process_relocs(Symbol_table* symtab,
Layout* layout,
Sized_relobj_file<size, false>* 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);
// Scan the relocations to look for symbol adjustments.
void
scan_relocs(Symbol_table* symtab,
Layout* layout,
Sized_relobj_file<size, false>* 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);
// Finalize the sections.
void
do_finalize_sections(Layout*, const Input_objects*, Symbol_table*);
// Return the value to use for a dynamic which requires special
// treatment.
uint64_t
do_dynsym_value(const Symbol*) const;
// Relocate a section.
void
relocate_section(const Relocate_info<size, false>*,
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*);
// Scan the relocs during a relocatable link.
void
scan_relocatable_relocs(Symbol_table* symtab,
Layout* layout,
Sized_relobj_file<size, false>* 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*);
// Emit relocations for a section.
void
relocate_relocs(
const Relocate_info<size, false>*,
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,
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);
// Return a string used to fill a code section with nops.
std::string
do_code_fill(section_size_type length) const;
// Return whether SYM is defined by the ABI.
bool
do_is_defined_by_abi(const Symbol* sym) const
{ return strcmp(sym->name(), "__tls_get_addr") == 0; }
// Return the symbol index to use for a target specific relocation.
// The only target specific relocation is R_X86_64_TLSDESC for a
// local symbol, which is an absolute reloc.
unsigned int
do_reloc_symbol_index(void*, unsigned int r_type) const
{
gold_assert(r_type == elfcpp::R_X86_64_TLSDESC);
return 0;
}
// Return the addend to use for a target specific relocation.
uint64_t
do_reloc_addend(void* arg, unsigned int r_type, uint64_t addend) const;
// Return the PLT section.
uint64_t
do_plt_address_for_global(const Symbol* gsym) const
{ return this->plt_section()->address_for_global(gsym); }
uint64_t
do_plt_address_for_local(const Relobj* relobj, unsigned int symndx) const
{ return this->plt_section()->address_for_local(relobj, symndx); }
// This function should be defined in targets that can use relocation
// types to determine (implemented in local_reloc_may_be_function_pointer
// and global_reloc_may_be_function_pointer)
// if a function's pointer is taken. ICF uses this in safe mode to only
// fold those functions whose pointer is defintely not taken. For x86_64
// pie binaries, safe ICF cannot be done by looking at relocation types.
bool
do_can_check_for_function_pointers() const
{ return !parameters->options().pie(); }
// Return the base for a DW_EH_PE_datarel encoding.
uint64_t
do_ehframe_datarel_base() const;
// Adjust -fsplit-stack code which calls non-split-stack code.
void
do_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;
// Return the size of the GOT section.
section_size_type
got_size() const
{
gold_assert(this->got_ != NULL);
return this->got_->data_size();
}
// Return the number of entries in the GOT.
unsigned int
got_entry_count() const
{
if (this->got_ == NULL)
return 0;
return this->got_size() / 8;
}
// Return the number of entries in the PLT.
unsigned int
plt_entry_count() const;
// Return the offset of the first non-reserved PLT entry.
unsigned int
first_plt_entry_offset() const;
// Return the size of each PLT entry.
unsigned int
plt_entry_size() const;
// Create the GOT section for an incremental update.
Output_data_got_base*
init_got_plt_for_update(Symbol_table* symtab,
Layout* layout,
unsigned int got_count,
unsigned int plt_count);
// Reserve a GOT entry for a local symbol, and regenerate any
// necessary dynamic relocations.
void
reserve_local_got_entry(unsigned int got_index,
Sized_relobj<size, false>* obj,
unsigned int r_sym,
unsigned int got_type);
// Reserve a GOT entry for a global symbol, and regenerate any
// necessary dynamic relocations.
void
reserve_global_got_entry(unsigned int got_index, Symbol* gsym,
unsigned int got_type);
// Register an existing PLT entry for a global symbol.
void
register_global_plt_entry(Symbol_table*, Layout*, unsigned int plt_index,
Symbol* gsym);
// Force a COPY relocation for a given symbol.
void
emit_copy_reloc(Symbol_table*, Symbol*, Output_section*, off_t);
// Apply an incremental relocation.
void
apply_relocation(const Relocate_info<size, false>* 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);
// Add a new reloc argument, returning the index in the vector.
size_t
add_tlsdesc_info(Sized_relobj_file<size, false>* object, unsigned int r_sym)
{
this->tlsdesc_reloc_info_.push_back(Tlsdesc_info(object, r_sym));
return this->tlsdesc_reloc_info_.size() - 1;
}
Output_data_plt_x86_64<size>*
make_data_plt(Layout* layout,
Output_data_got<64, false>* got,
Output_data_got_plt_x86_64* got_plt,
Output_data_space* got_irelative)
{
return this->do_make_data_plt(layout, got, got_plt, got_irelative);
}
Output_data_plt_x86_64<size>*
make_data_plt(Layout* layout,
Output_data_got<64, false>* got,
Output_data_got_plt_x86_64* got_plt,
Output_data_space* got_irelative,
unsigned int plt_count)
{
return this->do_make_data_plt(layout, got, got_plt, got_irelative,
plt_count);
}
virtual Output_data_plt_x86_64<size>*
do_make_data_plt(Layout* layout,
Output_data_got<64, false>* got,
Output_data_got_plt_x86_64* got_plt,
Output_data_space* got_irelative)
{
return new Output_data_plt_x86_64_standard<size>(layout, got, got_plt,
got_irelative);
}
virtual Output_data_plt_x86_64<size>*
do_make_data_plt(Layout* layout,
Output_data_got<64, false>* got,
Output_data_got_plt_x86_64* got_plt,
Output_data_space* got_irelative,
unsigned int plt_count)
{
return new Output_data_plt_x86_64_standard<size>(layout, got, got_plt,
got_irelative,
plt_count);
}
private:
// The class which scans relocations.
class Scan
{
public:
Scan()
: issued_non_pic_error_(false)
{ }
static inline int
get_reference_flags(unsigned int r_type);
inline void
local(Symbol_table* symtab, Layout* layout, Target_x86_64* target,
Sized_relobj_file<size, false>* object,
unsigned int data_shndx,
Output_section* output_section,
const elfcpp::Rela<size, false>& reloc, unsigned int r_type,
const elfcpp::Sym<size, false>& lsym,
bool is_discarded);
inline void
global(Symbol_table* symtab, Layout* layout, Target_x86_64* target,
Sized_relobj_file<size, false>* object,
unsigned int data_shndx,
Output_section* output_section,
const elfcpp::Rela<size, false>& reloc, unsigned int r_type,
Symbol* gsym);
inline bool
local_reloc_may_be_function_pointer(Symbol_table* symtab, Layout* layout,
Target_x86_64* target,
Sized_relobj_file<size, false>* object,
unsigned int data_shndx,
Output_section* output_section,
const elfcpp::Rela<size, false>& reloc,
unsigned int r_type,
const elfcpp::Sym<size, false>& lsym);
inline bool
global_reloc_may_be_function_pointer(Symbol_table* symtab, Layout* layout,
Target_x86_64* target,
Sized_relobj_file<size, false>* object,
unsigned int data_shndx,
Output_section* output_section,
const elfcpp::Rela<size, false>& reloc,
unsigned int r_type,
Symbol* gsym);
private:
static void
unsupported_reloc_local(Sized_relobj_file<size, false>*,
unsigned int r_type);
static void
unsupported_reloc_global(Sized_relobj_file<size, false>*,
unsigned int r_type, Symbol*);
void
check_non_pic(Relobj*, unsigned int r_type, Symbol*);
inline bool
possible_function_pointer_reloc(unsigned int r_type);
bool
reloc_needs_plt_for_ifunc(Sized_relobj_file<size, false>*,
unsigned int r_type);
// Whether we have issued an error about a non-PIC compilation.
bool issued_non_pic_error_;
};
// The class which implements relocation.
class Relocate
{
public:
Relocate()
: skip_call_tls_get_addr_(false)
{ }
~Relocate()
{
if (this->skip_call_tls_get_addr_)
{
// FIXME: This needs to specify the location somehow.
gold_error(_("missing expected TLS relocation"));
}
}
// Do a relocation. Return false if the caller should not issue
// any warnings about this relocation.
inline bool
relocate(const Relocate_info<size, false>*, Target_x86_64*,
Output_section*,
size_t relnum, const elfcpp::Rela<size, false>&,
unsigned int r_type, const Sized_symbol<size>*,
const Symbol_value<size>*,
unsigned char*, typename elfcpp::Elf_types<size>::Elf_Addr,
section_size_type);
private:
// Do a TLS relocation.
inline void
relocate_tls(const Relocate_info<size, false>*, Target_x86_64*,
size_t relnum, const elfcpp::Rela<size, false>&,
unsigned int r_type, const Sized_symbol<size>*,
const Symbol_value<size>*,
unsigned char*, typename elfcpp::Elf_types<size>::Elf_Addr,
section_size_type);
// Do a TLS General-Dynamic to Initial-Exec transition.
inline void
tls_gd_to_ie(const Relocate_info<size, false>*, size_t relnum,
Output_segment* tls_segment,
const elfcpp::Rela<size, false>&, unsigned int r_type,
typename elfcpp::Elf_types<size>::Elf_Addr value,
unsigned char* view,
typename elfcpp::Elf_types<size>::Elf_Addr,
section_size_type view_size);
// Do a TLS General-Dynamic to Local-Exec transition.
inline void
tls_gd_to_le(const Relocate_info<size, false>*, size_t relnum,
Output_segment* tls_segment,
const elfcpp::Rela<size, false>&, unsigned int r_type,
typename elfcpp::Elf_types<size>::Elf_Addr value,
unsigned char* view,
section_size_type view_size);
// Do a TLSDESC-style General-Dynamic to Initial-Exec transition.
inline void
tls_desc_gd_to_ie(const Relocate_info<size, false>*, size_t relnum,
Output_segment* tls_segment,
const elfcpp::Rela<size, false>&, unsigned int r_type,
typename elfcpp::Elf_types<size>::Elf_Addr value,
unsigned char* view,
typename elfcpp::Elf_types<size>::Elf_Addr,
section_size_type view_size);
// Do a TLSDESC-style General-Dynamic to Local-Exec transition.
inline void
tls_desc_gd_to_le(const Relocate_info<size, false>*, size_t relnum,
Output_segment* tls_segment,
const elfcpp::Rela<size, false>&, unsigned int r_type,
typename elfcpp::Elf_types<size>::Elf_Addr value,
unsigned char* view,
section_size_type view_size);
// Do a TLS Local-Dynamic to Local-Exec transition.
inline void
tls_ld_to_le(const Relocate_info<size, false>*, size_t relnum,
Output_segment* tls_segment,
const elfcpp::Rela<size, false>&, unsigned int r_type,
typename elfcpp::Elf_types<size>::Elf_Addr value,
unsigned char* view,
section_size_type view_size);
// Do a TLS Initial-Exec to Local-Exec transition.
static inline void
tls_ie_to_le(const Relocate_info<size, false>*, size_t relnum,
Output_segment* tls_segment,
const elfcpp::Rela<size, false>&, unsigned int r_type,
typename elfcpp::Elf_types<size>::Elf_Addr value,
unsigned char* view,
section_size_type view_size);
// This is set if we should skip the next reloc, which should be a
// PLT32 reloc against ___tls_get_addr.
bool skip_call_tls_get_addr_;
};
// A class which returns the size required for a relocation type,
// used while scanning relocs during a relocatable link.
class Relocatable_size_for_reloc
{
public:
unsigned int
get_size_for_reloc(unsigned int, Relobj*);
};
// Adjust TLS relocation type based on the options and whether this
// is a local symbol.
static tls::Tls_optimization
optimize_tls_reloc(bool is_final, int r_type);
// Get the GOT section, creating it if necessary.
Output_data_got<64, false>*
got_section(Symbol_table*, Layout*);
// Get the GOT PLT section.
Output_data_got_plt_x86_64*
got_plt_section() const
{
gold_assert(this->got_plt_ != NULL);
return this->got_plt_;
}
// Get the GOT section for TLSDESC entries.
Output_data_got<64, false>*
got_tlsdesc_section() const
{
gold_assert(this->got_tlsdesc_ != NULL);
return this->got_tlsdesc_;
}
// Create the PLT section.
void
make_plt_section(Symbol_table* symtab, Layout* layout);
// Create a PLT entry for a global symbol.
void
make_plt_entry(Symbol_table*, Layout*, Symbol*);
// Create a PLT entry for a local STT_GNU_IFUNC symbol.
void
make_local_ifunc_plt_entry(Symbol_table*, Layout*,
Sized_relobj_file<size, false>* relobj,
unsigned int local_sym_index);
// Define the _TLS_MODULE_BASE_ symbol in the TLS segment.
void
define_tls_base_symbol(Symbol_table*, Layout*);
// Create the reserved PLT and GOT entries for the TLS descriptor resolver.
void
reserve_tlsdesc_entries(Symbol_table* symtab, Layout* layout);
// Create a GOT entry for the TLS module index.
unsigned int
got_mod_index_entry(Symbol_table* symtab, Layout* layout,
Sized_relobj_file<size, false>* object);
// Get the PLT section.
Output_data_plt_x86_64<size>*
plt_section() const
{
gold_assert(this->plt_ != NULL);
return this->plt_;
}
// Get the dynamic reloc section, creating it if necessary.
Reloc_section*
rela_dyn_section(Layout*);
// Get the section to use for TLSDESC relocations.
Reloc_section*
rela_tlsdesc_section(Layout*) const;
// Get the section to use for IRELATIVE relocations.
Reloc_section*
rela_irelative_section(Layout*);
// Add a potential copy relocation.
void
copy_reloc(Symbol_table* symtab, Layout* layout,
Sized_relobj_file<size, false>* object,
unsigned int shndx, Output_section* output_section,
Symbol* sym, const elfcpp::Rela<size, false>& reloc)
{
this->copy_relocs_.copy_reloc(symtab, layout,
symtab->get_sized_symbol<size>(sym),
object, shndx, output_section,
reloc, this->rela_dyn_section(layout));
}
// Information about this specific target which we pass to the
// general Target structure.
static const Target::Target_info x86_64_info;
// The types of GOT entries needed for this platform.
// These values are exposed to the ABI in an incremental link.
// Do not renumber existing values without changing the version
// number of the .gnu_incremental_inputs section.
enum Got_type
{
GOT_TYPE_STANDARD = 0, // GOT entry for a regular symbol
GOT_TYPE_TLS_OFFSET = 1, // GOT entry for TLS offset
GOT_TYPE_TLS_PAIR = 2, // GOT entry for TLS module/offset pair
GOT_TYPE_TLS_DESC = 3 // GOT entry for TLS_DESC pair
};
// This type is used as the argument to the target specific
// relocation routines. The only target specific reloc is
// R_X86_64_TLSDESC against a local symbol.
struct Tlsdesc_info
{
Tlsdesc_info(Sized_relobj_file<size, false>* a_object, unsigned int a_r_sym)
: object(a_object), r_sym(a_r_sym)
{ }
// The object in which the local symbol is defined.
Sized_relobj_file<size, false>* object;
// The local symbol index in the object.
unsigned int r_sym;
};
// The GOT section.
Output_data_got<64, false>* got_;
// The PLT section.
Output_data_plt_x86_64<size>* plt_;
// The GOT PLT section.
Output_data_got_plt_x86_64* got_plt_;
// The GOT section for IRELATIVE relocations.
Output_data_space* got_irelative_;
// The GOT section for TLSDESC relocations.
Output_data_got<64, false>* got_tlsdesc_;
// The _GLOBAL_OFFSET_TABLE_ symbol.
Symbol* global_offset_table_;
// The dynamic reloc section.
Reloc_section* rela_dyn_;
// The section to use for IRELATIVE relocs.
Reloc_section* rela_irelative_;
// Relocs saved to avoid a COPY reloc.
Copy_relocs<elfcpp::SHT_RELA, size, false> copy_relocs_;
// Offset of the GOT entry for the TLS module index.
unsigned int got_mod_index_offset_;
// We handle R_X86_64_TLSDESC against a local symbol as a target
// specific relocation. Here we store the object and local symbol
// index for the relocation.
std::vector<Tlsdesc_info> tlsdesc_reloc_info_;
// True if the _TLS_MODULE_BASE_ symbol has been defined.
bool tls_base_symbol_defined_;
};
template<>
const Target::Target_info Target_x86_64<64>::x86_64_info =
{
64, // size
false, // is_big_endian
elfcpp::EM_X86_64, // machine_code
false, // has_make_symbol
false, // has_resolve
true, // has_code_fill
true, // is_default_stack_executable
true, // can_icf_inline_merge_sections
'\0', // wrap_char
"/lib/ld64.so.1", // program interpreter
0x400000, // default_text_segment_address
0x1000, // abi_pagesize (overridable by -z max-page-size)
0x1000, // common_pagesize (overridable by -z common-page-size)
false, // isolate_execinstr
0, // rosegment_gap
elfcpp::SHN_UNDEF, // small_common_shndx
elfcpp::SHN_X86_64_LCOMMON, // large_common_shndx
0, // small_common_section_flags
elfcpp::SHF_X86_64_LARGE, // large_common_section_flags
NULL, // attributes_section
NULL, // attributes_vendor
"_start" // entry_symbol_name
};
template<>
const Target::Target_info Target_x86_64<32>::x86_64_info =
{
32, // size
false, // is_big_endian
elfcpp::EM_X86_64, // machine_code
false, // has_make_symbol
false, // has_resolve
true, // has_code_fill
true, // is_default_stack_executable
true, // can_icf_inline_merge_sections
'\0', // wrap_char
"/libx32/ldx32.so.1", // program interpreter
0x400000, // default_text_segment_address
0x1000, // abi_pagesize (overridable by -z max-page-size)
0x1000, // common_pagesize (overridable by -z common-page-size)
false, // isolate_execinstr
0, // rosegment_gap
elfcpp::SHN_UNDEF, // small_common_shndx
elfcpp::SHN_X86_64_LCOMMON, // large_common_shndx
0, // small_common_section_flags
elfcpp::SHF_X86_64_LARGE, // large_common_section_flags
NULL, // attributes_section
NULL, // attributes_vendor
"_start" // entry_symbol_name
};
// This is called when a new output section is created. This is where
// we handle the SHF_X86_64_LARGE.
template<int size>
void
Target_x86_64<size>::do_new_output_section(Output_section* os) const
{
if ((os->flags() & elfcpp::SHF_X86_64_LARGE) != 0)
os->set_is_large_section();
}
// Get the GOT section, creating it if necessary.
template<int size>
Output_data_got<64, false>*
Target_x86_64<size>::got_section(Symbol_table* symtab, Layout* layout)
{
if (this->got_ == NULL)
{
gold_assert(symtab != NULL && layout != NULL);
// When using -z now, we can treat .got.plt as a relro section.
// Without -z now, it is modified after program startup by lazy
// PLT relocations.
bool is_got_plt_relro = parameters->options().now();
Output_section_order got_order = (is_got_plt_relro
? ORDER_RELRO
: ORDER_RELRO_LAST);
Output_section_order got_plt_order = (is_got_plt_relro
? ORDER_RELRO
: ORDER_NON_RELRO_FIRST);
this->got_ = new Output_data_got<64, false>();
layout->add_output_section_data(".got", elfcpp::SHT_PROGBITS,
(elfcpp::SHF_ALLOC
| elfcpp::SHF_WRITE),
this->got_, got_order, true);
this->got_plt_ = new Output_data_got_plt_x86_64(layout);
layout->add_output_section_data(".got.plt", elfcpp::SHT_PROGBITS,
(elfcpp::SHF_ALLOC
| elfcpp::SHF_WRITE),
this->got_plt_, got_plt_order,
is_got_plt_relro);
// The first three entries are reserved.
this->got_plt_->set_current_data_size(3 * 8);
if (!is_got_plt_relro)
{
// Those bytes can go into the relro segment.
layout->increase_relro(3 * 8);
}
// Define _GLOBAL_OFFSET_TABLE_ at the start of the PLT.
this->global_offset_table_ =
symtab->define_in_output_data("_GLOBAL_OFFSET_TABLE_", NULL,
Symbol_table::PREDEFINED,
this->got_plt_,
0, 0, elfcpp::STT_OBJECT,
elfcpp::STB_LOCAL,
elfcpp::STV_HIDDEN, 0,
false, false);
// If there are any IRELATIVE relocations, they get GOT entries
// in .got.plt after the jump slot entries.
this->got_irelative_ = new Output_data_space(8, "** GOT IRELATIVE PLT");
layout->add_output_section_data(".got.plt", elfcpp::SHT_PROGBITS,
(elfcpp::SHF_ALLOC
| elfcpp::SHF_WRITE),
this->got_irelative_,
got_plt_order, is_got_plt_relro);
// If there are any TLSDESC relocations, they get GOT entries in
// .got.plt after the jump slot and IRELATIVE entries.
this->got_tlsdesc_ = new Output_data_got<64, false>();
layout->add_output_section_data(".got.plt", elfcpp::SHT_PROGBITS,
(elfcpp::SHF_ALLOC
| elfcpp::SHF_WRITE),
this->got_tlsdesc_,
got_plt_order, is_got_plt_relro);
}
return this->got_;
}
// Get the dynamic reloc section, creating it if necessary.
template<int size>
typename Target_x86_64<size>::Reloc_section*
Target_x86_64<size>::rela_dyn_section(Layout* layout)
{
if (this->rela_dyn_ == NULL)
{
gold_assert(layout != NULL);
this->rela_dyn_ = new Reloc_section(parameters->options().combreloc());
layout->add_output_section_data(".rela.dyn", elfcpp::SHT_RELA,
elfcpp::SHF_ALLOC, this->rela_dyn_,
ORDER_DYNAMIC_RELOCS, false);
}
return this->rela_dyn_;
}
// Get the section to use for IRELATIVE relocs, creating it if
// necessary. These go in .rela.dyn, but only after all other dynamic
// relocations. They need to follow the other dynamic relocations so
// that they can refer to global variables initialized by those
// relocs.
template<int size>
typename Target_x86_64<size>::Reloc_section*
Target_x86_64<size>::rela_irelative_section(Layout* layout)
{
if (this->rela_irelative_ == NULL)
{
// Make sure we have already created the dynamic reloc section.
this->rela_dyn_section(layout);
this->rela_irelative_ = new Reloc_section(false);
layout->add_output_section_data(".rela.dyn", elfcpp::SHT_RELA,
elfcpp::SHF_ALLOC, this->rela_irelative_,
ORDER_DYNAMIC_RELOCS, false);
gold_assert(this->rela_dyn_->output_section()
== this->rela_irelative_->output_section());
}
return this->rela_irelative_;
}
// Write the first three reserved words of the .got.plt section.
// The remainder of the section is written while writing the PLT
// in Output_data_plt_i386::do_write.
void
Output_data_got_plt_x86_64::do_write(Output_file* of)
{
// The first entry in the GOT is the address of the .dynamic section
// aka the PT_DYNAMIC segment. The next two entries are reserved.
// We saved space for them when we created the section in
// Target_x86_64::got_section.
const off_t got_file_offset = this->offset();
gold_assert(this->data_size() >= 24);
unsigned char* const got_view = of->get_output_view(got_file_offset, 24);
Output_section* dynamic = this->layout_->dynamic_section();
uint64_t dynamic_addr = dynamic == NULL ? 0 : dynamic->address();
elfcpp::Swap<64, false>::writeval(got_view, dynamic_addr);
memset(got_view + 8, 0, 16);
of->write_output_view(got_file_offset, 24, got_view);
}
// Initialize the PLT section.
template<int size>
void
Output_data_plt_x86_64<size>::init(Layout* layout)
{
this->rel_ = new Reloc_section(false);
layout->add_output_section_data(".rela.plt", elfcpp::SHT_RELA,
elfcpp::SHF_ALLOC, this->rel_,
ORDER_DYNAMIC_PLT_RELOCS, false);
}
template<int size>
void
Output_data_plt_x86_64<size>::do_adjust_output_section(Output_section* os)
{
os->set_entsize(this->get_plt_entry_size());
}
// Add an entry to the PLT.
template<int size>
void
Output_data_plt_x86_64<size>::add_entry(Symbol_table* symtab, Layout* layout,
Symbol* gsym)
{
gold_assert(!gsym->has_plt_offset());
unsigned int plt_index;
off_t plt_offset;
section_offset_type got_offset;
unsigned int* pcount;
unsigned int offset;
unsigned int reserved;
Output_section_data_build* got;
if (gsym->type() == elfcpp::STT_GNU_IFUNC
&& gsym->can_use_relative_reloc(false))
{
pcount = &this->irelative_count_;
offset = 0;
reserved = 0;
got = this->got_irelative_;
}
else
{
pcount = &this->count_;
offset = 1;
reserved = 3;
got = this->got_plt_;
}
if (!this->is_data_size_valid())
{
// Note that when setting the PLT offset for a non-IRELATIVE
// entry we skip the initial reserved PLT entry.
plt_index = *pcount + offset;
plt_offset = plt_index * this->get_plt_entry_size();
++*pcount;
got_offset = (plt_index - offset + reserved) * 8;
gold_assert(got_offset == got->current_data_size());
// Every PLT entry needs a GOT entry which points back to the PLT
// entry (this will be changed by the dynamic linker, normally
// lazily when the function is called).
got->set_current_data_size(got_offset + 8);
}
else
{
// FIXME: This is probably not correct for IRELATIVE relocs.
// For incremental updates, find an available slot.
plt_offset = this->free_list_.allocate(this->get_plt_entry_size(),
this->get_plt_entry_size(), 0);
if (plt_offset == -1)
gold_fallback(_("out of patch space (PLT);"
" relink with --incremental-full"));
// The GOT and PLT entries have a 1-1 correspondance, so the GOT offset
// can be calculated from the PLT index, adjusting for the three
// reserved entries at the beginning of the GOT.
plt_index = plt_offset / this->get_plt_entry_size() - 1;
got_offset = (plt_index - offset + reserved) * 8;
}
gsym->set_plt_offset(plt_offset);
// Every PLT entry needs a reloc.
this->add_relocation(symtab, layout, gsym, got_offset);
// Note that we don't need to save the symbol. The contents of the
// PLT are independent of which symbols are used. The symbols only
// appear in the relocations.
}
// Add an entry to the PLT for a local STT_GNU_IFUNC symbol. Return
// the PLT offset.
template<int size>
unsigned int
Output_data_plt_x86_64<size>::add_local_ifunc_entry(
Symbol_table* symtab,
Layout* layout,
Sized_relobj_file<size, false>* relobj,
unsigned int local_sym_index)
{
unsigned int plt_offset = this->irelative_count_ * this->get_plt_entry_size();
++this->irelative_count_;
section_offset_type got_offset = this->got_irelative_->current_data_size();
// Every PLT entry needs a GOT entry which points back to the PLT
// entry.
this->got_irelative_->set_current_data_size(got_offset + 8);
// Every PLT entry needs a reloc.
Reloc_section* rela = this->rela_irelative(symtab, layout);
rela->add_symbolless_local_addend(relobj, local_sym_index,
elfcpp::R_X86_64_IRELATIVE,
this->got_irelative_, got_offset, 0);
return plt_offset;
}
// Add the relocation for a PLT entry.
template<int size>
void
Output_data_plt_x86_64<size>::add_relocation(Symbol_table* symtab,
Layout* layout,
Symbol* gsym,
unsigned int got_offset)
{
if (gsym->type() == elfcpp::STT_GNU_IFUNC
&& gsym->can_use_relative_reloc(false))
{
Reloc_section* rela = this->rela_irelative(symtab, layout);
rela->add_symbolless_global_addend(gsym, elfcpp::R_X86_64_IRELATIVE,
this->got_irelative_, got_offset, 0);
}
else
{
gsym->set_needs_dynsym_entry();
this->rel_->add_global(gsym, elfcpp::R_X86_64_JUMP_SLOT, this->got_plt_,
got_offset, 0);
}
}
// Return where the TLSDESC relocations should go, creating it if
// necessary. These follow the JUMP_SLOT relocations.
template<int size>
typename Output_data_plt_x86_64<size>::Reloc_section*
Output_data_plt_x86_64<size>::rela_tlsdesc(Layout* layout)
{
if (this->tlsdesc_rel_ == NULL)
{
this->tlsdesc_rel_ = new Reloc_section(false);
layout->add_output_section_data(".rela.plt", elfcpp::SHT_RELA,
elfcpp::SHF_ALLOC, this->tlsdesc_rel_,
ORDER_DYNAMIC_PLT_RELOCS, false);
gold_assert(this->tlsdesc_rel_->output_section()
== this->rel_->output_section());
}
return this->tlsdesc_rel_;
}
// Return where the IRELATIVE relocations should go in the PLT. These
// follow the JUMP_SLOT and the TLSDESC relocations.
template<int size>
typename Output_data_plt_x86_64<size>::Reloc_section*
Output_data_plt_x86_64<size>::rela_irelative(Symbol_table* symtab,
Layout* layout)
{
if (this->irelative_rel_ == NULL)
{
// Make sure we have a place for the TLSDESC relocations, in
// case we see any later on.
this->rela_tlsdesc(layout);
this->irelative_rel_ = new Reloc_section(false);
layout->add_output_section_data(".rela.plt", elfcpp::SHT_RELA,
elfcpp::SHF_ALLOC, this->irelative_rel_,
ORDER_DYNAMIC_PLT_RELOCS, false);
gold_assert(this->irelative_rel_->output_section()
== this->rel_->output_section());
if (parameters->doing_static_link())
{
// A statically linked executable will only have a .rela.plt
// section to hold R_X86_64_IRELATIVE relocs for
// STT_GNU_IFUNC symbols. The library will use these
// symbols to locate the IRELATIVE relocs at program startup
// time.
symtab->define_in_output_data("__rela_iplt_start", NULL,
Symbol_table::PREDEFINED,
this->irelative_rel_, 0, 0,
elfcpp::STT_NOTYPE, elfcpp::STB_GLOBAL,
elfcpp::STV_HIDDEN, 0, false, true);
symtab->define_in_output_data("__rela_iplt_end", NULL,
Symbol_table::PREDEFINED,
this->irelative_rel_, 0, 0,
elfcpp::STT_NOTYPE, elfcpp::STB_GLOBAL,
elfcpp::STV_HIDDEN, 0, true, true);
}
}
return this->irelative_rel_;
}
// Return the PLT address to use for a global symbol.
template<int size>
uint64_t
Output_data_plt_x86_64<size>::address_for_global(const Symbol* gsym)
{
uint64_t offset = 0;
if (gsym->type() == elfcpp::STT_GNU_IFUNC
&& gsym->can_use_relative_reloc(false))
offset = (this->count_ + 1) * this->get_plt_entry_size();
return this->address() + offset + gsym->plt_offset();
}
// Return the PLT address to use for a local symbol. These are always
// IRELATIVE relocs.
template<int size>
uint64_t
Output_data_plt_x86_64<size>::address_for_local(const Relobj* object,
unsigned int r_sym)
{
return (this->address()
+ (this->count_ + 1) * this->get_plt_entry_size()
+ object->local_plt_offset(r_sym));
}
// Set the final size.
template<int size>
void
Output_data_plt_x86_64<size>::set_final_data_size()
{
unsigned int count = this->count_ + this->irelative_count_;
if (this->has_tlsdesc_entry())
++count;
this->set_data_size((count + 1) * this->get_plt_entry_size());
}
// The first entry in the PLT for an executable.
template<int size>
const unsigned char
Output_data_plt_x86_64_standard<size>::first_plt_entry[plt_entry_size] =
{
// From AMD64 ABI Draft 0.98, page 76
0xff, 0x35, // pushq contents of memory address
0, 0, 0, 0, // replaced with address of .got + 8
0xff, 0x25, // jmp indirect
0, 0, 0, 0, // replaced with address of .got + 16
0x90, 0x90, 0x90, 0x90 // noop (x4)
};
template<int size>
void
Output_data_plt_x86_64_standard<size>::do_fill_first_plt_entry(
unsigned char* pov,
typename elfcpp::Elf_types<size>::Elf_Addr got_address,
typename elfcpp::Elf_types<size>::Elf_Addr plt_address)
{
memcpy(pov, first_plt_entry, plt_entry_size);
// We do a jmp relative to the PC at the end of this instruction.
elfcpp::Swap_unaligned<32, false>::writeval(pov + 2,
(got_address + 8
- (plt_address + 6)));
elfcpp::Swap<32, false>::writeval(pov + 8,
(got_address + 16
- (plt_address + 12)));
}
// Subsequent entries in the PLT for an executable.
template<int size>
const unsigned char
Output_data_plt_x86_64_standard<size>::plt_entry[plt_entry_size] =
{
// From AMD64 ABI Draft 0.98, page 76
0xff, 0x25, // jmpq indirect
0, 0, 0, 0, // replaced with address of symbol in .got
0x68, // pushq immediate
0, 0, 0, 0, // replaced with offset into relocation table
0xe9, // jmpq relative
0, 0, 0, 0 // replaced with offset to start of .plt
};
template<int size>
unsigned int
Output_data_plt_x86_64_standard<size>::do_fill_plt_entry(
unsigned char* pov,
typename elfcpp::Elf_types<size>::Elf_Addr got_address,
typename elfcpp::Elf_types<size>::Elf_Addr plt_address,
unsigned int got_offset,
unsigned int plt_offset,
unsigned int plt_index)
{
// Check PC-relative offset overflow in PLT entry.
uint64_t plt_got_pcrel_offset = (got_address + got_offset
- (plt_address + plt_offset + 6));
if (Bits<32>::has_overflow(plt_got_pcrel_offset))
gold_error(_("PC-relative offset overflow in PLT entry %d"),
plt_index + 1);
memcpy(pov, plt_entry, plt_entry_size);
elfcpp::Swap_unaligned<32, false>::writeval(pov + 2,
plt_got_pcrel_offset);
elfcpp::Swap_unaligned<32, false>::writeval(pov + 7, plt_index);
elfcpp::Swap<32, false>::writeval(pov + 12,
- (plt_offset + plt_entry_size));
return 6;
}
// The reserved TLSDESC entry in the PLT for an executable.
template<int size>
const unsigned char
Output_data_plt_x86_64_standard<size>::tlsdesc_plt_entry[plt_entry_size] =
{
// From Alexandre Oliva, "Thread-Local Storage Descriptors for IA32
// and AMD64/EM64T", Version 0.9.4 (2005-10-10).
0xff, 0x35, // pushq x(%rip)
0, 0, 0, 0, // replaced with address of linkmap GOT entry (at PLTGOT + 8)
0xff, 0x25, // jmpq *y(%rip)
0, 0, 0, 0, // replaced with offset of reserved TLSDESC_GOT entry
0x0f, 0x1f, // nop
0x40, 0
};
template<int size>
void
Output_data_plt_x86_64_standard<size>::do_fill_tlsdesc_entry(
unsigned char* pov,
typename elfcpp::Elf_types<size>::Elf_Addr got_address,
typename elfcpp::Elf_types<size>::Elf_Addr plt_address,
typename elfcpp::Elf_types<size>::Elf_Addr got_base,
unsigned int tlsdesc_got_offset,
unsigned int plt_offset)
{
memcpy(pov, tlsdesc_plt_entry, plt_entry_size);
elfcpp::Swap_unaligned<32, false>::writeval(pov + 2,
(got_address + 8
- (plt_address + plt_offset
+ 6)));
elfcpp::Swap_unaligned<32, false>::writeval(pov + 8,
(got_base
+ tlsdesc_got_offset
- (plt_address + plt_offset
+ 12)));
}
// The .eh_frame unwind information for the PLT.
template<int size>
const unsigned char
Output_data_plt_x86_64<size>::plt_eh_frame_cie[plt_eh_frame_cie_size] =
{
1, // CIE version.
'z', // Augmentation: augmentation size included.
'R', // Augmentation: FDE encoding included.
'\0', // End of augmentation string.
1, // Code alignment factor.
0x78, // Data alignment factor.
16, // Return address column.
1, // Augmentation size.
(elfcpp::DW_EH_PE_pcrel // FDE encoding.
| elfcpp::DW_EH_PE_sdata4),
elfcpp::DW_CFA_def_cfa, 7, 8, // DW_CFA_def_cfa: r7 (rsp) ofs 8.
elfcpp::DW_CFA_offset + 16, 1,// DW_CFA_offset: r16 (rip) at cfa-8.
elfcpp::DW_CFA_nop, // Align to 16 bytes.
elfcpp::DW_CFA_nop
};
template<int size>
const unsigned char
Output_data_plt_x86_64_standard<size>::plt_eh_frame_fde[plt_eh_frame_fde_size] =
{
0, 0, 0, 0, // Replaced with offset to .plt.
0, 0, 0, 0, // Replaced with size of .plt.
0, // Augmentation size.
elfcpp::DW_CFA_def_cfa_offset, 16, // DW_CFA_def_cfa_offset: 16.
elfcpp::DW_CFA_advance_loc + 6, // Advance 6 to __PLT__ + 6.
elfcpp::DW_CFA_def_cfa_offset, 24, // DW_CFA_def_cfa_offset: 24.
elfcpp::DW_CFA_advance_loc + 10, // Advance 10 to __PLT__ + 16.
elfcpp::DW_CFA_def_cfa_expression, // DW_CFA_def_cfa_expression.
11, // Block length.
elfcpp::DW_OP_breg7, 8, // Push %rsp + 8.
elfcpp::DW_OP_breg16, 0, // Push %rip.
elfcpp::DW_OP_lit15, // Push 0xf.
elfcpp::DW_OP_and, // & (%rip & 0xf).
elfcpp::DW_OP_lit11, // Push 0xb.
elfcpp::DW_OP_ge, // >= ((%rip & 0xf) >= 0xb)
elfcpp::DW_OP_lit3, // Push 3.
elfcpp::DW_OP_shl, // << (((%rip & 0xf) >= 0xb) << 3)
elfcpp::DW_OP_plus, // + ((((%rip&0xf)>=0xb)<<3)+%rsp+8
elfcpp::DW_CFA_nop, // Align to 32 bytes.
elfcpp::DW_CFA_nop,
elfcpp::DW_CFA_nop,
elfcpp::DW_CFA_nop
};
// Write out the PLT. This uses the hand-coded instructions above,
// and adjusts them as needed. This is specified by the AMD64 ABI.
template<int size>
void
Output_data_plt_x86_64<size>::do_write(Output_file* of)
{
const off_t offset = this->offset();
const section_size_type oview_size =
convert_to_section_size_type(this->data_size());
unsigned char* const oview = of->get_output_view(offset, oview_size);
const off_t got_file_offset = this->got_plt_->offset();
gold_assert(parameters->incremental_update()
|| (got_file_offset + this->got_plt_->data_size()
== this->got_irelative_->offset()));
const section_size_type got_size =
convert_to_section_size_type(this->got_plt_->data_size()
+ this->got_irelative_->data_size());
unsigned char* const got_view = of->get_output_view(got_file_offset,
got_size);
unsigned char* pov = oview;
// The base address of the .plt section.
typename elfcpp::Elf_types<size>::Elf_Addr plt_address = this->address();
// The base address of the .got section.
typename elfcpp::Elf_types<size>::Elf_Addr got_base = this->got_->address();
// The base address of the PLT portion of the .got section,
// which is where the GOT pointer will point, and where the
// three reserved GOT entries are located.
typename elfcpp::Elf_types<size>::Elf_Addr got_address
= this->got_plt_->address();
this->fill_first_plt_entry(pov, got_address, plt_address);
pov += this->get_plt_entry_size();
// The first three entries in the GOT are reserved, and are written
// by Output_data_got_plt_x86_64::do_write.
unsigned char* got_pov = got_view + 24;
unsigned int plt_offset = this->get_plt_entry_size();
unsigned int got_offset = 24;
const unsigned int count = this->count_ + this->irelative_count_;
for (unsigned int plt_index = 0;
plt_index < count;
++plt_index,
pov += this->get_plt_entry_size(),
got_pov += 8,
plt_offset += this->get_plt_entry_size(),
got_offset += 8)
{
// Set and adjust the PLT entry itself.
unsigned int lazy_offset = this->fill_plt_entry(pov,
got_address, plt_address,
got_offset, plt_offset,
plt_index);
// Set the entry in the GOT.
elfcpp::Swap<64, false>::writeval(got_pov,
plt_address + plt_offset + lazy_offset);
}
if (this->has_tlsdesc_entry())
{
// Set and adjust the reserved TLSDESC PLT entry.
unsigned int tlsdesc_got_offset = this->get_tlsdesc_got_offset();
this->fill_tlsdesc_entry(pov, got_address, plt_address, got_base,
tlsdesc_got_offset, plt_offset);
pov += this->get_plt_entry_size();
}
gold_assert(static_cast<section_size_type>(pov - oview) == oview_size);
gold_assert(static_cast<section_size_type>(got_pov - got_view) == got_size);
of->write_output_view(offset, oview_size, oview);
of->write_output_view(got_file_offset, got_size, got_view);
}
// Create the PLT section.
template<int size>
void
Target_x86_64<size>::make_plt_section(Symbol_table* symtab, Layout* layout)
{
if (this->plt_ == NULL)
{
// Create the GOT sections first.
this->got_section(symtab, layout);
this->plt_ = this->make_data_plt(layout, this->got_, this->got_plt_,
this->got_irelative_);
// Add unwind information if requested.
if (parameters->options().ld_generated_unwind_info())
this->plt_->add_eh_frame(layout);
layout->add_output_section_data(".plt", elfcpp::SHT_PROGBITS,
(elfcpp::SHF_ALLOC
| elfcpp::SHF_EXECINSTR),
this->plt_, ORDER_PLT, false);
// Make the sh_info field of .rela.plt point to .plt.
Output_section* rela_plt_os = this->plt_->rela_plt()->output_section();
rela_plt_os->set_info_section(this->plt_->output_section());
}
}
// Return the section for TLSDESC relocations.
template<int size>
typename Target_x86_64<size>::Reloc_section*
Target_x86_64<size>::rela_tlsdesc_section(Layout* layout) const
{
return this->plt_section()->rela_tlsdesc(layout);
}
// Create a PLT entry for a global symbol.
template<int size>
void
Target_x86_64<size>::make_plt_entry(Symbol_table* symtab, Layout* layout,
Symbol* gsym)
{
if (gsym->has_plt_offset())
return;
if (this->plt_ == NULL)
this->make_plt_section(symtab, layout);
this->plt_->add_entry(symtab, layout, gsym);
}
// Make a PLT entry for a local STT_GNU_IFUNC symbol.
template<int size>
void
Target_x86_64<size>::make_local_ifunc_plt_entry(
Symbol_table* symtab, Layout* layout,
Sized_relobj_file<size, false>* relobj,
unsigned int local_sym_index)
{
if (relobj->local_has_plt_offset(local_sym_index))
return;
if (this->plt_ == NULL)
this->make_plt_section(symtab, layout);
unsigned int plt_offset = this->plt_->add_local_ifunc_entry(symtab, layout,
relobj,
local_sym_index);
relobj->set_local_plt_offset(local_sym_index, plt_offset);
}
// Return the number of entries in the PLT.
template<int size>
unsigned int
Target_x86_64<size>::plt_entry_count() const
{
if (this->plt_ == NULL)
return 0;
return this->plt_->entry_count();
}
// Return the offset of the first non-reserved PLT entry.
template<int size>
unsigned int
Target_x86_64<size>::first_plt_entry_offset() const
{
return this->plt_->first_plt_entry_offset();
}
// Return the size of each PLT entry.
template<int size>
unsigned int
Target_x86_64<size>::plt_entry_size() const
{
return this->plt_->get_plt_entry_size();
}
// Create the GOT and PLT sections for an incremental update.
template<int size>
Output_data_got_base*
Target_x86_64<size>::init_got_plt_for_update(Symbol_table* symtab,
Layout* layout,
unsigned int got_count,
unsigned int plt_count)
{
gold_assert(this->got_ == NULL);
this->got_ = new Output_data_got<64, false>(got_count * 8);
layout->add_output_section_data(".got", elfcpp::SHT_PROGBITS,
(elfcpp::SHF_ALLOC
| elfcpp::SHF_WRITE),
this->got_, ORDER_RELRO_LAST,
true);
// Add the three reserved entries.
this->got_plt_ = new Output_data_got_plt_x86_64(layout, (plt_count + 3) * 8);
layout->add_output_section_data(".got.plt", elfcpp::SHT_PROGBITS,
(elfcpp::SHF_ALLOC
| elfcpp::SHF_WRITE),
this->got_plt_, ORDER_NON_RELRO_FIRST,
false);
// Define _GLOBAL_OFFSET_TABLE_ at the start of the PLT.
this->global_offset_table_ =
symtab->define_in_output_data("_GLOBAL_OFFSET_TABLE_", NULL,
Symbol_table::PREDEFINED,
this->got_plt_,
0, 0, elfcpp::STT_OBJECT,
elfcpp::STB_LOCAL,
elfcpp::STV_HIDDEN, 0,
false, false);
// If there are any TLSDESC relocations, they get GOT entries in
// .got.plt after the jump slot entries.
// FIXME: Get the count for TLSDESC entries.
this->got_tlsdesc_ = new Output_data_got<64, false>(0);
layout->add_output_section_data(".got.plt", elfcpp::SHT_PROGBITS,
elfcpp::SHF_ALLOC | elfcpp::SHF_WRITE,
this->got_tlsdesc_,
ORDER_NON_RELRO_FIRST, false);
// If there are any IRELATIVE relocations, they get GOT entries in
// .got.plt after the jump slot and TLSDESC entries.
this->got_irelative_ = new Output_data_space(0, 8, "** GOT IRELATIVE PLT");
layout->add_output_section_data(".got.plt", elfcpp::SHT_PROGBITS,
elfcpp::SHF_ALLOC | elfcpp::SHF_WRITE,
this->got_irelative_,
ORDER_NON_RELRO_FIRST, false);
// Create the PLT section.
this->plt_ = this->make_data_plt(layout, this->got_,
this->got_plt_,
this->got_irelative_,
plt_count);
// Add unwind information if requested.
if (parameters->options().ld_generated_unwind_info())
this->plt_->add_eh_frame(layout);
layout->add_output_section_data(".plt", elfcpp::SHT_PROGBITS,
elfcpp::SHF_ALLOC | elfcpp::SHF_EXECINSTR,
this->plt_, ORDER_PLT, false);
// Make the sh_info field of .rela.plt point to .plt.
Output_section* rela_plt_os = this->plt_->rela_plt()->output_section();
rela_plt_os->set_info_section(this->plt_->output_section());
// Create the rela_dyn section.
this->rela_dyn_section(layout);
return this->got_;
}
// Reserve a GOT entry for a local symbol, and regenerate any
// necessary dynamic relocations.
template<int size>
void
Target_x86_64<size>::reserve_local_got_entry(
unsigned int got_index,
Sized_relobj<size, false>* obj,
unsigned int r_sym,
unsigned int got_type)
{
unsigned int got_offset = got_index * 8;
Reloc_section* rela_dyn = this->rela_dyn_section(NULL);
this->got_->reserve_local(got_index, obj, r_sym, got_type);
switch (got_type)
{
case GOT_TYPE_STANDARD:
if (parameters->options().output_is_position_independent())
rela_dyn->add_local_relative(obj, r_sym, elfcpp::R_X86_64_RELATIVE,
this->got_, got_offset, 0, false);
break;
case GOT_TYPE_TLS_OFFSET:
rela_dyn->add_local(obj, r_sym, elfcpp::R_X86_64_TPOFF64,
this->got_, got_offset, 0);
break;
case GOT_TYPE_TLS_PAIR:
this->got_->reserve_slot(got_index + 1);
rela_dyn->add_local(obj, r_sym, elfcpp::R_X86_64_DTPMOD64,
this->got_, got_offset, 0);
break;
case GOT_TYPE_TLS_DESC:
gold_fatal(_("TLS_DESC not yet supported for incremental linking"));
// this->got_->reserve_slot(got_index + 1);
// rela_dyn->add_target_specific(elfcpp::R_X86_64_TLSDESC, arg,
// this->got_, got_offset, 0);
break;
default:
gold_unreachable();
}
}
// Reserve a GOT entry for a global symbol, and regenerate any
// necessary dynamic relocations.
template<int size>
void
Target_x86_64<size>::reserve_global_got_entry(unsigned int got_index,
Symbol* gsym,
unsigned int got_type)
{
unsigned int got_offset = got_index * 8;
Reloc_section* rela_dyn = this->rela_dyn_section(NULL);
this->got_->reserve_global(got_index, gsym, got_type);
switch (got_type)
{
case GOT_TYPE_STANDARD:
if (!gsym->final_value_is_known())
{
if (gsym->is_from_dynobj()
|| gsym->is_undefined()
|| gsym->is_preemptible()
|| gsym->type() == elfcpp::STT_GNU_IFUNC)
rela_dyn->add_global(gsym, elfcpp::R_X86_64_GLOB_DAT,
this->got_, got_offset, 0);
else
rela_dyn->add_global_relative(gsym, elfcpp::R_X86_64_RELATIVE,
this->got_, got_offset, 0, false);
}
break;
case GOT_TYPE_TLS_OFFSET:
rela_dyn->add_global_relative(gsym, elfcpp::R_X86_64_TPOFF64,
this->got_, got_offset, 0, false);
break;
case GOT_TYPE_TLS_PAIR:
this->got_->reserve_slot(got_index + 1);
rela_dyn->add_global_relative(gsym, elfcpp::R_X86_64_DTPMOD64,
this->got_, got_offset, 0, false);
rela_dyn->add_global_relative(gsym, elfcpp::R_X86_64_DTPOFF64,
this->got_, got_offset + 8, 0, false);
break;
case GOT_TYPE_TLS_DESC:
this->got_->reserve_slot(got_index + 1);
rela_dyn->add_global_relative(gsym, elfcpp::R_X86_64_TLSDESC,
this->got_, got_offset, 0, false);
break;
default:
gold_unreachable();
}
}
// Register an existing PLT entry for a global symbol.
template<int size>
void
Target_x86_64<size>::register_global_plt_entry(Symbol_table* symtab,
Layout* layout,
unsigned int plt_index,
Symbol* gsym)
{
gold_assert(this->plt_ != NULL);
gold_assert(!gsym->has_plt_offset());
this->plt_->reserve_slot(plt_index);
gsym->set_plt_offset((plt_index + 1) * this->plt_entry_size());
unsigned int got_offset = (plt_index + 3) * 8;
this->plt_->add_relocation(symtab, layout, gsym, got_offset);
}
// Force a COPY relocation for a given symbol.
template<int size>
void
Target_x86_64<size>::emit_copy_reloc(
Symbol_table* symtab, Symbol* sym, Output_section* os, off_t offset)
{
this->copy_relocs_.emit_copy_reloc(symtab,
symtab->get_sized_symbol<size>(sym),
os,
offset,
this->rela_dyn_section(NULL));
}
// Define the _TLS_MODULE_BASE_ symbol in the TLS segment.
template<int size>
void
Target_x86_64<size>::define_tls_base_symbol(Symbol_table* symtab,
Layout* layout)
{
if (this->tls_base_symbol_defined_)
return;
Output_segment* tls_segment = layout->tls_segment();
if (tls_segment != NULL)
{
bool is_exec = parameters->options().output_is_executable();
symtab->define_in_output_segment("_TLS_MODULE_BASE_", NULL,
Symbol_table::PREDEFINED,
tls_segment, 0, 0,
elfcpp::STT_TLS,
elfcpp::STB_LOCAL,
elfcpp::STV_HIDDEN, 0,
(is_exec
? Symbol::SEGMENT_END
: Symbol::SEGMENT_START),
true);
}
this->tls_base_symbol_defined_ = true;
}
// Create the reserved PLT and GOT entries for the TLS descriptor resolver.
template<int size>
void
Target_x86_64<size>::reserve_tlsdesc_entries(Symbol_table* symtab,
Layout* layout)
{
if (this->plt_ == NULL)
this->make_plt_section(symtab, layout);
if (!this->plt_->has_tlsdesc_entry())
{
// Allocate the TLSDESC_GOT entry.
Output_data_got<64, false>* got = this->got_section(symtab, layout);
unsigned int got_offset = got->add_constant(0);
// Allocate the TLSDESC_PLT entry.
this->plt_->reserve_tlsdesc_entry(got_offset);
}
}
// Create a GOT entry for the TLS module index.
template<int size>
unsigned int
Target_x86_64<size>::got_mod_index_entry(Symbol_table* symtab, Layout* layout,
Sized_relobj_file<size, false>* object)
{
if (this->got_mod_index_offset_ == -1U)
{
gold_assert(symtab != NULL && layout != NULL && object != NULL);
Reloc_section* rela_dyn = this->rela_dyn_section(layout);
Output_data_got<64, false>* got = this->got_section(symtab, layout);
unsigned int got_offset = got->add_constant(0);
rela_dyn->add_local(object, 0, elfcpp::R_X86_64_DTPMOD64, got,
got_offset, 0);
got->add_constant(0);
this->got_mod_index_offset_ = got_offset;
}
return this->got_mod_index_offset_;
}
// Optimize the TLS relocation type based on what we know about the
// symbol. IS_FINAL is true if the final address of this symbol is
// known at link time.
template<int size>
tls::Tls_optimization
Target_x86_64<size>::optimize_tls_reloc(bool is_final, int r_type)
{
// If we are generating a shared library, then we can't do anything
// in the linker.
if (parameters->options().shared())
return tls::TLSOPT_NONE;
switch (r_type)
{
case elfcpp::R_X86_64_TLSGD:
case elfcpp::R_X86_64_GOTPC32_TLSDESC:
case elfcpp::R_X86_64_TLSDESC_CALL:
// These are General-Dynamic which permits fully general TLS
// access. Since we know that we are generating an executable,
// we can convert this to Initial-Exec. If we also know that
// this is a local symbol, we can further switch to Local-Exec.
if (is_final)
return tls::TLSOPT_TO_LE;
return tls::TLSOPT_TO_IE;
case elfcpp::R_X86_64_TLSLD:
// This is Local-Dynamic, which refers to a local symbol in the
// dynamic TLS block. Since we know that we generating an
// executable, we can switch to Local-Exec.
return tls::TLSOPT_TO_LE;
case elfcpp::R_X86_64_DTPOFF32:
case elfcpp::R_X86_64_DTPOFF64:
// Another Local-Dynamic reloc.
return tls::TLSOPT_TO_LE;
case elfcpp::R_X86_64_GOTTPOFF:
// These are Initial-Exec relocs which get the thread offset
// from the GOT. If we know that we are linking against the
// local symbol, we can switch to Local-Exec, which links the
// thread offset into the instruction.
if (is_final)
return tls::TLSOPT_TO_LE;
return tls::TLSOPT_NONE;
case elfcpp::R_X86_64_TPOFF32:
// When we already have Local-Exec, there is nothing further we
// can do.
return tls::TLSOPT_NONE;
default:
gold_unreachable();
}
}
// Get the Reference_flags for a particular relocation.
template<int size>
int
Target_x86_64<size>::Scan::get_reference_flags(unsigned int r_type)
{
switch (r_type)
{
case elfcpp::R_X86_64_NONE:
case elfcpp::R_X86_64_GNU_VTINHERIT:
case elfcpp::R_X86_64_GNU_VTENTRY:
case elfcpp::R_X86_64_GOTPC32:
case elfcpp::R_X86_64_GOTPC64:
// No symbol reference.
return 0;
case elfcpp::R_X86_64_64:
case elfcpp::R_X86_64_32:
case elfcpp::R_X86_64_32S:
case elfcpp::R_X86_64_16:
case elfcpp::R_X86_64_8:
return Symbol::ABSOLUTE_REF;
case elfcpp::R_X86_64_PC64:
case elfcpp::R_X86_64_PC32:
case elfcpp::R_X86_64_PC32_BND:
case elfcpp::R_X86_64_PC16:
case elfcpp::R_X86_64_PC8:
case elfcpp::R_X86_64_GOTOFF64:
return Symbol::RELATIVE_REF;
case elfcpp::R_X86_64_PLT32:
case elfcpp::R_X86_64_PLT32_BND:
case elfcpp::R_X86_64_PLTOFF64:
return Symbol::FUNCTION_CALL | Symbol::RELATIVE_REF;
case elfcpp::R_X86_64_GOT64:
case elfcpp::R_X86_64_GOT32:
case elfcpp::R_X86_64_GOTPCREL64:
case elfcpp::R_X86_64_GOTPCREL:
case elfcpp::R_X86_64_GOTPLT64:
// Absolute in GOT.
return Symbol::ABSOLUTE_REF;
case elfcpp::R_X86_64_TLSGD: // Global-dynamic
case elfcpp::R_X86_64_GOTPC32_TLSDESC: // Global-dynamic (from ~oliva url)
case elfcpp::R_X86_64_TLSDESC_CALL:
case elfcpp::R_X86_64_TLSLD: // Local-dynamic
case elfcpp::R_X86_64_DTPOFF32:
case elfcpp::R_X86_64_DTPOFF64:
case elfcpp::R_X86_64_GOTTPOFF: // Initial-exec
case elfcpp::R_X86_64_TPOFF32: // Local-exec
return Symbol::TLS_REF;
case elfcpp::R_X86_64_COPY:
case elfcpp::R_X86_64_GLOB_DAT:
case elfcpp::R_X86_64_JUMP_SLOT:
case elfcpp::R_X86_64_RELATIVE:
case elfcpp::R_X86_64_IRELATIVE:
case elfcpp::R_X86_64_TPOFF64:
case elfcpp::R_X86_64_DTPMOD64:
case elfcpp::R_X86_64_TLSDESC:
case elfcpp::R_X86_64_SIZE32:
case elfcpp::R_X86_64_SIZE64:
default:
// Not expected. We will give an error later.
return 0;
}
}
// Report an unsupported relocation against a local symbol.
template<int size>
void
Target_x86_64<size>::Scan::unsupported_reloc_local(
Sized_relobj_file<size, false>* object,
unsigned int r_type)
{
gold_error(_("%s: unsupported reloc %u against local symbol"),
object->name().c_str(), r_type);
}
// We are about to emit a dynamic relocation of type R_TYPE. If the
// dynamic linker does not support it, issue an error. The GNU linker
// only issues a non-PIC error for an allocated read-only section.
// Here we know the section is allocated, but we don't know that it is
// read-only. But we check for all the relocation types which the
// glibc dynamic linker supports, so it seems appropriate to issue an
// error even if the section is not read-only. If GSYM is not NULL,
// it is the symbol the relocation is against; if it is NULL, the
// relocation is against a local symbol.
template<int size>
void
Target_x86_64<size>::Scan::check_non_pic(Relobj* object, unsigned int r_type,
Symbol* gsym)
{
switch (r_type)
{
// These are the relocation types supported by glibc for x86_64
// which should always work.
case elfcpp::R_X86_64_RELATIVE:
case elfcpp::R_X86_64_IRELATIVE:
case elfcpp::R_X86_64_GLOB_DAT:
case elfcpp::R_X86_64_JUMP_SLOT:
case elfcpp::R_X86_64_DTPMOD64:
case elfcpp::R_X86_64_DTPOFF64:
case elfcpp::R_X86_64_TPOFF64:
case elfcpp::R_X86_64_64:
case elfcpp::R_X86_64_COPY:
return;
// glibc supports these reloc types, but they can overflow.
case elfcpp::R_X86_64_PC32:
case elfcpp::R_X86_64_PC32_BND:
// A PC relative reference is OK against a local symbol or if
// the symbol is defined locally.
if (gsym == NULL
|| (!gsym->is_from_dynobj()
&& !gsym->is_undefined()
&& !gsym->is_preemptible()))
return;
/* Fall through. */
case elfcpp::R_X86_64_32:
// R_X86_64_32 is OK for x32.
if (size == 32 && r_type == elfcpp::R_X86_64_32)
return;
if (this->issued_non_pic_error_)
return;
gold_assert(parameters->options().output_is_position_independent());
if (gsym == NULL)
object->error(_("requires dynamic R_X86_64_32 reloc which may "
"overflow at runtime; recompile with -fPIC"));
else
{
const char *r_name;
switch (r_type)
{
case elfcpp::R_X86_64_32:
r_name = "R_X86_64_32";
break;
case elfcpp::R_X86_64_PC32:
r_name = "R_X86_64_PC32";
break;
case elfcpp::R_X86_64_PC32_BND:
r_name = "R_X86_64_PC32_BND";
break;
default:
gold_unreachable();
break;
}
object->error(_("requires dynamic %s reloc against '%s' "
"which may overflow at runtime; recompile "
"with -fPIC"),
r_name, gsym->name());
}
this->issued_non_pic_error_ = true;
return;
default:
// This prevents us from issuing more than one error per reloc
// section. But we can still wind up issuing more than one
// error per object file.
if (this->issued_non_pic_error_)
return;
gold_assert(parameters->options().output_is_position_independent());
object->error(_("requires unsupported dynamic reloc %u; "
"recompile with -fPIC"),
r_type);
this->issued_non_pic_error_ = true;
return;
case elfcpp::R_X86_64_NONE:
gold_unreachable();
}
}
// Return whether we need to make a PLT entry for a relocation of the
// given type against a STT_GNU_IFUNC symbol.
template<int size>
bool
Target_x86_64<size>::Scan::reloc_needs_plt_for_ifunc(
Sized_relobj_file<size, false>* object,
unsigned int r_type)
{
int flags = Scan::get_reference_flags(r_type);
if (flags & Symbol::TLS_REF)
gold_error(_("%s: unsupported TLS reloc %u for IFUNC symbol"),
object->name().c_str(), r_type);
return flags != 0;
}
// Scan a relocation for a local symbol.
template<int size>
inline void
Target_x86_64<size>::Scan::local(Symbol_table* symtab,
Layout* layout,
Target_x86_64<size>* target,
Sized_relobj_file<size, false>* object,
unsigned int data_shndx,
Output_section* output_section,
const elfcpp::Rela<size, false>& reloc,
unsigned int r_type,
const elfcpp::Sym<size, false>& lsym,
bool is_discarded)
{
if (is_discarded)
return;
// A local STT_GNU_IFUNC symbol may require a PLT entry.
bool is_ifunc = lsym.get_st_type() == elfcpp::STT_GNU_IFUNC;
if (is_ifunc && this->reloc_needs_plt_for_ifunc(object, r_type))
{
unsigned int r_sym = elfcpp::elf_r_sym<size>(reloc.get_r_info());
target->make_local_ifunc_plt_entry(symtab, layout, object, r_sym);
}
switch (r_type)
{
case elfcpp::R_X86_64_NONE:
case elfcpp::R_X86_64_GNU_VTINHERIT:
case elfcpp::R_X86_64_GNU_VTENTRY:
break;
case elfcpp::R_X86_64_64:
// If building a shared library (or a position-independent
// executable), we need to create a dynamic relocation for this
// location. The relocation applied at link time will apply the
// link-time value, so we flag the location with an
// R_X86_64_RELATIVE relocation so the dynamic loader can
// relocate it easily.
if (parameters->options().output_is_position_independent())
{
unsigned int r_sym = elfcpp::elf_r_sym<size>(reloc.get_r_info());
Reloc_section* rela_dyn = target->rela_dyn_section(layout);
rela_dyn->add_local_relative(object, r_sym,
(size == 32
? elfcpp::R_X86_64_RELATIVE64
: elfcpp::R_X86_64_RELATIVE),
output_section, data_shndx,
reloc.get_r_offset(),
reloc.get_r_addend(), is_ifunc);
}
break;
case elfcpp::R_X86_64_32:
case elfcpp::R_X86_64_32S:
case elfcpp::R_X86_64_16:
case elfcpp::R_X86_64_8:
// If building a shared library (or a position-independent
// executable), we need to create a dynamic relocation for this
// location. We can't use an R_X86_64_RELATIVE relocation
// because that is always a 64-bit relocation.
if (parameters->options().output_is_position_independent())
{
// Use R_X86_64_RELATIVE relocation for R_X86_64_32 under x32.
if (size == 32 && r_type == elfcpp::R_X86_64_32)
{
unsigned int r_sym = elfcpp::elf_r_sym<size>(reloc.get_r_info());
Reloc_section* rela_dyn = target->rela_dyn_section(layout);
rela_dyn->add_local_relative(object, r_sym,
elfcpp::R_X86_64_RELATIVE,
output_section, data_shndx,
reloc.get_r_offset(),
reloc.get_r_addend(), is_ifunc);
break;
}
this->check_non_pic(object, r_type, NULL);
Reloc_section* rela_dyn = target->rela_dyn_section(layout);
unsigned int r_sym = elfcpp::elf_r_sym<size>(reloc.get_r_info());
if (lsym.get_st_type() != elfcpp::STT_SECTION)
rela_dyn->add_local(object, r_sym, r_type, output_section,
data_shndx, reloc.get_r_offset(),
reloc.get_r_addend());
else
{
gold_assert(lsym.get_st_value() == 0);
unsigned int shndx = lsym.get_st_shndx();
bool is_ordinary;
shndx = object->adjust_sym_shndx(r_sym, shndx,
&is_ordinary);
if (!is_ordinary)
object->error(_("section symbol %u has bad shndx %u"),
r_sym, shndx);
else
rela_dyn->add_local_section(object, shndx,
r_type, output_section,
data_shndx, reloc.get_r_offset(),
reloc.get_r_addend());
}
}
break;
case elfcpp::R_X86_64_PC64:
case elfcpp::R_X86_64_PC32:
case elfcpp::R_X86_64_PC32_BND:
case elfcpp::R_X86_64_PC16:
case elfcpp::R_X86_64_PC8:
break;
case elfcpp::R_X86_64_PLT32:
case elfcpp::R_X86_64_PLT32_BND:
// Since we know this is a local symbol, we can handle this as a
// PC32 reloc.
break;
case elfcpp::R_X86_64_GOTPC32:
case elfcpp::R_X86_64_GOTOFF64:
case elfcpp::R_X86_64_GOTPC64:
case elfcpp::R_X86_64_PLTOFF64:
// We need a GOT section.
target->got_section(symtab, layout);
// For PLTOFF64, we'd normally want a PLT section, but since we
// know this is a local symbol, no PLT is needed.
break;
case elfcpp::R_X86_64_GOT64:
case elfcpp::R_X86_64_GOT32:
case elfcpp::R_X86_64_GOTPCREL64:
case elfcpp::R_X86_64_GOTPCREL:
case elfcpp::R_X86_64_GOTPLT64:
{
// The symbol requires a GOT entry.
Output_data_got<64, false>* got = target->got_section(symtab, layout);
unsigned int r_sym = elfcpp::elf_r_sym<size>(reloc.get_r_info());
// For a STT_GNU_IFUNC symbol we want the PLT offset. That
// lets function pointers compare correctly with shared
// libraries. Otherwise we would need an IRELATIVE reloc.
bool is_new;
if (is_ifunc)
is_new = got->add_local_plt(object, r_sym, GOT_TYPE_STANDARD);
else
is_new = got->add_local(object, r_sym, GOT_TYPE_STANDARD);
if (is_new)
{
// If we are generating a shared object, we need to add a
// dynamic relocation for this symbol's GOT entry.
if (parameters->options().output_is_position_independent())
{
Reloc_section* rela_dyn = target->rela_dyn_section(layout);
// R_X86_64_RELATIVE assumes a 64-bit relocation.
if (r_type != elfcpp::R_X86_64_GOT32)
{
unsigned int got_offset =
object->local_got_offset(r_sym, GOT_TYPE_STANDARD);
rela_dyn->add_local_relative(object, r_sym,
elfcpp::R_X86_64_RELATIVE,
got, got_offset, 0, is_ifunc);
}
else
{
this->check_non_pic(object, r_type, NULL);
gold_assert(lsym.get_st_type() != elfcpp::STT_SECTION);
rela_dyn->add_local(
object, r_sym, r_type, got,
object->local_got_offset(r_sym, GOT_TYPE_STANDARD), 0);
}
}
}
// For GOTPLT64, we'd normally want a PLT section, but since
// we know this is a local symbol, no PLT is needed.
}
break;
case elfcpp::R_X86_64_COPY:
case elfcpp::R_X86_64_GLOB_DAT:
case elfcpp::R_X86_64_JUMP_SLOT:
case elfcpp::R_X86_64_RELATIVE:
case elfcpp::R_X86_64_IRELATIVE:
// These are outstanding tls relocs, which are unexpected when linking
case elfcpp::R_X86_64_TPOFF64:
case elfcpp::R_X86_64_DTPMOD64:
case elfcpp::R_X86_64_TLSDESC:
gold_error(_("%s: unexpected reloc %u in object file"),
object->name().c_str(), r_type);
break;
// These are initial tls relocs, which are expected when linking
case elfcpp::R_X86_64_TLSGD: // Global-dynamic
case elfcpp::R_X86_64_GOTPC32_TLSDESC: // Global-dynamic (from ~oliva url)
case elfcpp::R_X86_64_TLSDESC_CALL:
case elfcpp::R_X86_64_TLSLD: // Local-dynamic
case elfcpp::R_X86_64_DTPOFF32:
case elfcpp::R_X86_64_DTPOFF64:
case elfcpp::R_X86_64_GOTTPOFF: // Initial-exec
case elfcpp::R_X86_64_TPOFF32: // Local-exec
{
bool output_is_shared = parameters->options().shared();
const tls::Tls_optimization optimized_type
= Target_x86_64<size>::optimize_tls_reloc(!output_is_shared,
r_type);
switch (r_type)
{
case elfcpp::R_X86_64_TLSGD: // General-dynamic
if (optimized_type == tls::TLSOPT_NONE)
{
// Create a pair of GOT entries for the module index and
// dtv-relative offset.
Output_data_got<64, false>* got
= target->got_section(symtab, layout);
unsigned int r_sym = elfcpp::elf_r_sym<size>(reloc.get_r_info());
unsigned int shndx = lsym.get_st_shndx();
bool is_ordinary;
shndx = object->adjust_sym_shndx(r_sym, shndx, &is_ordinary);
if (!is_ordinary)
object->error(_("local symbol %u has bad shndx %u"),
r_sym, shndx);
else
got->add_local_pair_with_rel(object, r_sym,
shndx,
GOT_TYPE_TLS_PAIR,
target->rela_dyn_section(layout),
elfcpp::R_X86_64_DTPMOD64);
}
else if (optimized_type != tls::TLSOPT_TO_LE)
unsupported_reloc_local(object, r_type);
break;
case elfcpp::R_X86_64_GOTPC32_TLSDESC:
target->define_tls_base_symbol(symtab, layout);
if (optimized_type == tls::TLSOPT_NONE)
{
// Create reserved PLT and GOT entries for the resolver.
target->reserve_tlsdesc_entries(symtab, layout);
// Generate a double GOT entry with an
// R_X86_64_TLSDESC reloc. The R_X86_64_TLSDESC reloc
// is resolved lazily, so the GOT entry needs to be in
// an area in .got.plt, not .got. Call got_section to
// make sure the section has been created.
target->got_section(symtab, layout);
Output_data_got<64, false>* got = target->got_tlsdesc_section();
unsigned int r_sym = elfcpp::elf_r_sym<size>(reloc.get_r_info());
if (!object->local_has_got_offset(r_sym, GOT_TYPE_TLS_DESC))
{
unsigned int got_offset = got->add_constant(0);
got->add_constant(0);
object->set_local_got_offset(r_sym, GOT_TYPE_TLS_DESC,
got_offset);
Reloc_section* rt = target->rela_tlsdesc_section(layout);
// We store the arguments we need in a vector, and
// use the index into the vector as the parameter
// to pass to the target specific routines.
uintptr_t intarg = target->add_tlsdesc_info(object, r_sym);
void* arg = reinterpret_cast<void*>(intarg);
rt->add_target_specific(elfcpp::R_X86_64_TLSDESC, arg,
got, got_offset, 0);
}
}
else if (optimized_type != tls::TLSOPT_TO_LE)
unsupported_reloc_local(object, r_type);
break;
case elfcpp::R_X86_64_TLSDESC_CALL:
break;
case elfcpp::R_X86_64_TLSLD: // Local-dynamic
if (optimized_type == tls::TLSOPT_NONE)
{
// Create a GOT entry for the module index.
target->got_mod_index_entry(symtab, layout, object);
}
else if (optimized_type != tls::TLSOPT_TO_LE)
unsupported_reloc_local(object, r_type);
break;
case elfcpp::R_X86_64_DTPOFF32:
case elfcpp::R_X86_64_DTPOFF64:
break;
case elfcpp::R_X86_64_GOTTPOFF: // Initial-exec
layout->set_has_static_tls();
if (optimized_type == tls::TLSOPT_NONE)
{
// Create a GOT entry for the tp-relative offset.
Output_data_got<64, false>* got
= target->got_section(symtab, layout);
unsigned int r_sym = elfcpp::elf_r_sym<size>(reloc.get_r_info());
got->add_local_with_rel(object, r_sym, GOT_TYPE_TLS_OFFSET,
target->rela_dyn_section(layout),
elfcpp::R_X86_64_TPOFF64);
}
else if (optimized_type != tls::TLSOPT_TO_LE)
unsupported_reloc_local(object, r_type);
break;
case elfcpp::R_X86_64_TPOFF32: // Local-exec
layout->set_has_static_tls();
if (output_is_shared)
unsupported_reloc_local(object, r_type);
break;
default:
gold_unreachable();
}
}
break;
case elfcpp::R_X86_64_SIZE32:
case elfcpp::R_X86_64_SIZE64:
default:
gold_error(_("%s: unsupported reloc %u against local symbol"),
object->name().c_str(), r_type);
break;
}
}
// Report an unsupported relocation against a global symbol.
template<int size>
void
Target_x86_64<size>::Scan::unsupported_reloc_global(
Sized_relobj_file<size, false>* object,
unsigned int r_type,
Symbol* gsym)
{
gold_error(_("%s: unsupported reloc %u against global symbol %s"),
object->name().c_str(), r_type, gsym->demangled_name().c_str());
}
// Returns true if this relocation type could be that of a function pointer.
template<int size>
inline bool
Target_x86_64<size>::Scan::possible_function_pointer_reloc(unsigned int r_type)
{
switch (r_type)
{
case elfcpp::R_X86_64_64:
case elfcpp::R_X86_64_32:
case elfcpp::R_X86_64_32S:
case elfcpp::R_X86_64_16:
case elfcpp::R_X86_64_8:
case elfcpp::R_X86_64_GOT64:
case elfcpp::R_X86_64_GOT32:
case elfcpp::R_X86_64_GOTPCREL64:
case elfcpp::R_X86_64_GOTPCREL:
case elfcpp::R_X86_64_GOTPLT64:
{
return true;
}
}
return false;
}
// For safe ICF, scan a relocation for a local symbol to check if it
// corresponds to a function pointer being taken. In that case mark
// the function whose pointer was taken as not foldable.
template<int size>
inline bool
Target_x86_64<size>::Scan::local_reloc_may_be_function_pointer(
Symbol_table* ,
Layout* ,
Target_x86_64<size>* ,
Sized_relobj_file<size, false>* ,
unsigned int ,
Output_section* ,
const elfcpp::Rela<size, false>& ,
unsigned int r_type,
const elfcpp::Sym<size, false>&)
{
// When building a shared library, do not fold any local symbols as it is
// not possible to distinguish pointer taken versus a call by looking at
// the relocation types.
return (parameters->options().shared()
|| possible_function_pointer_reloc(r_type));
}
// For safe ICF, scan a relocation for a global symbol to check if it
// corresponds to a function pointer being taken. In that case mark
// the function whose pointer was taken as not foldable.
template<int size>
inline bool
Target_x86_64<size>::Scan::global_reloc_may_be_function_pointer(
Symbol_table*,
Layout* ,
Target_x86_64<size>* ,
Sized_relobj_file<size, false>* ,
unsigned int ,
Output_section* ,
const elfcpp::Rela<size, false>& ,
unsigned int r_type,
Symbol* gsym)
{
// When building a shared library, do not fold symbols whose visibility
// is hidden, internal or protected.
return ((parameters->options().shared()
&& (gsym->visibility() == elfcpp::STV_INTERNAL
|| gsym->visibility() == elfcpp::STV_PROTECTED
|| gsym->visibility() == elfcpp::STV_HIDDEN))
|| possible_function_pointer_reloc(r_type));
}
// Scan a relocation for a global symbol.
template<int size>
inline void
Target_x86_64<size>::Scan::global(Symbol_table* symtab,
Layout* layout,
Target_x86_64<size>* target,
Sized_relobj_file<size, false>* object,
unsigned int data_shndx,
Output_section* output_section,
const elfcpp::Rela<size, false>& reloc,
unsigned int r_type,
Symbol* gsym)
{
// A STT_GNU_IFUNC symbol may require a PLT entry.
if (gsym->type() == elfcpp::STT_GNU_IFUNC
&& this->reloc_needs_plt_for_ifunc(object, r_type))
target->make_plt_entry(symtab, layout, gsym);
switch (r_type)
{
case elfcpp::R_X86_64_NONE:
case elfcpp::R_X86_64_GNU_VTINHERIT:
case elfcpp::R_X86_64_GNU_VTENTRY:
break;
case elfcpp::R_X86_64_64:
case elfcpp::R_X86_64_32:
case elfcpp::R_X86_64_32S:
case elfcpp::R_X86_64_16:
case elfcpp::R_X86_64_8:
{
// Make a PLT entry if necessary.
if (gsym->needs_plt_entry())
{
target->make_plt_entry(symtab, layout, gsym);
// Since this is not a PC-relative relocation, we may be
// taking the address of a function. In that case we need to
// set the entry in the dynamic symbol table to the address of
// the PLT entry.
if (gsym->is_from_dynobj() && !parameters->options().shared())
gsym->set_needs_dynsym_value();
}
// Make a dynamic relocation if necessary.
if (gsym->needs_dynamic_reloc(Scan::get_reference_flags(r_type)))
{
if (!parameters->options().output_is_position_independent()
&& gsym->may_need_copy_reloc())
{
target->copy_reloc(symtab, layout, object,
data_shndx, output_section, gsym, reloc);
}
else if (((size == 64 && r_type == elfcpp::R_X86_64_64)
|| (size == 32 && r_type == elfcpp::R_X86_64_32))
&& gsym->type() == elfcpp::STT_GNU_IFUNC
&& gsym->can_use_relative_reloc(false)
&& !gsym->is_from_dynobj()
&& !gsym->is_undefined()
&& !gsym->is_preemptible())
{
// Use an IRELATIVE reloc for a locally defined
// STT_GNU_IFUNC symbol. This makes a function
// address in a PIE executable match the address in a
// shared library that it links against.
Reloc_section* rela_dyn =
target->rela_irelative_section(layout);
unsigned int r_type = elfcpp::R_X86_64_IRELATIVE;
rela_dyn->add_symbolless_global_addend(gsym, r_type,
output_section, object,
data_shndx,
reloc.get_r_offset(),
reloc.get_r_addend());
}
else if (((size == 64 && r_type == elfcpp::R_X86_64_64)
|| (size == 32 && r_type == elfcpp::R_X86_64_32))
&& gsym->can_use_relative_reloc(false))
{
Reloc_section* rela_dyn = target->rela_dyn_section(layout);
rela_dyn->add_global_relative(gsym, elfcpp::R_X86_64_RELATIVE,
output_section, object,
data_shndx,
reloc.get_r_offset(),
reloc.get_r_addend(), false);
}
else
{
this->check_non_pic(object, r_type, gsym);
Reloc_section* rela_dyn = target->rela_dyn_section(layout);
rela_dyn->add_global(gsym, r_type, output_section, object,
data_shndx, reloc.get_r_offset(),
reloc.get_r_addend());
}
}
}
break;
case elfcpp::R_X86_64_PC64:
case elfcpp::R_X86_64_PC32:
case elfcpp::R_X86_64_PC32_BND:
case elfcpp::R_X86_64_PC16:
case elfcpp::R_X86_64_PC8:
{
// Make a PLT entry if necessary.
if (gsym->needs_plt_entry())
target->make_plt_entry(symtab, layout, gsym);
// Make a dynamic relocation if necessary.
if (gsym->needs_dynamic_reloc(Scan::get_reference_flags(r_type)))
{
if (parameters->options().output_is_executable()
&& gsym->may_need_copy_reloc())
{
target->copy_reloc(symtab, layout, object,
data_shndx, output_section, gsym, reloc);
}
else
{
this->check_non_pic(object, r_type, gsym);
Reloc_section* rela_dyn = target->rela_dyn_section(layout);
rela_dyn->add_global(gsym, r_type, output_section, object,
data_shndx, reloc.get_r_offset(),
reloc.get_r_addend());
}
}
}
break;
case elfcpp::R_X86_64_GOT64:
case elfcpp::R_X86_64_GOT32:
case elfcpp::R_X86_64_GOTPCREL64:
case elfcpp::R_X86_64_GOTPCREL:
case elfcpp::R_X86_64_GOTPLT64:
{
// The symbol requires a GOT entry.
Output_data_got<64, false>* got = target->got_section(symtab, layout);
if (gsym->final_value_is_known())
{
// For a STT_GNU_IFUNC symbol we want the PLT address.
if (gsym->type() == elfcpp::STT_GNU_IFUNC)
got->add_global_plt(gsym, GOT_TYPE_STANDARD);
else
got->add_global(gsym, GOT_TYPE_STANDARD);
}
else
{
// If this symbol is not fully resolved, we need to add a
// dynamic relocation for it.
Reloc_section* rela_dyn = target->rela_dyn_section(layout);
// Use a GLOB_DAT rather than a RELATIVE reloc if:
//
// 1) The symbol may be defined in some other module.
//
// 2) We are building a shared library and this is a
// protected symbol; using GLOB_DAT means that the dynamic
// linker can use the address of the PLT in the main
// executable when appropriate so that function address
// comparisons work.
//
// 3) This is a STT_GNU_IFUNC symbol in position dependent
// code, again so that function address comparisons work.
if (gsym->is_from_dynobj()
|| gsym->is_undefined()
|| gsym->is_preemptible()
|| (gsym->visibility() == elfcpp::STV_PROTECTED
&& parameters->options().shared())
|| (gsym->type() == elfcpp::STT_GNU_IFUNC
&& parameters->options().output_is_position_independent()))
got->add_global_with_rel(gsym, GOT_TYPE_STANDARD, rela_dyn,
elfcpp::R_X86_64_GLOB_DAT);
else
{
// For a STT_GNU_IFUNC symbol we want to write the PLT
// offset into the GOT, so that function pointer
// comparisons work correctly.
bool is_new;
if (gsym->type() != elfcpp::STT_GNU_IFUNC)
is_new = got->add_global(gsym, GOT_TYPE_STANDARD);
else
{
is_new = got->add_global_plt(gsym, GOT_TYPE_STANDARD);
// Tell the dynamic linker to use the PLT address
// when resolving relocations.
if (gsym->is_from_dynobj()
&& !parameters->options().shared())
gsym->set_needs_dynsym_value();
}
if (is_new)
{
unsigned int got_off = gsym->got_offset(GOT_TYPE_STANDARD);
rela_dyn->add_global_relative(gsym,
elfcpp::R_X86_64_RELATIVE,
got, got_off, 0, false);
}
}
}
}
break;
case elfcpp::R_X86_64_PLT32:
case elfcpp::R_X86_64_PLT32_BND:
// If the symbol is fully resolved, this is just a PC32 reloc.
// Otherwise we need a PLT entry.
if (gsym->final_value_is_known())
break;
// If building a shared library, we can also skip the PLT entry
// if the symbol is defined in the output file and is protected
// or hidden.
if (gsym->is_defined()
&& !gsym->is_from_dynobj()
&& !gsym->is_preemptible())
break;
target->make_plt_entry(symtab, layout, gsym);
break;
case elfcpp::R_X86_64_GOTPC32:
case elfcpp::R_X86_64_GOTOFF64:
case elfcpp::R_X86_64_GOTPC64:
case elfcpp::R_X86_64_PLTOFF64:
// We need a GOT section.
target->got_section(symtab, layout);
// For PLTOFF64, we also need a PLT entry (but only if the
// symbol is not fully resolved).
if (r_type == elfcpp::R_X86_64_PLTOFF64
&& !gsym->final_value_is_known())
target->make_plt_entry(symtab, layout, gsym);
break;
case elfcpp::R_X86_64_COPY:
case elfcpp::R_X86_64_GLOB_DAT:
case elfcpp::R_X86_64_JUMP_SLOT:
case elfcpp::R_X86_64_RELATIVE:
case elfcpp::R_X86_64_IRELATIVE:
// These are outstanding tls relocs, which are unexpected when linking
case elfcpp::R_X86_64_TPOFF64:
case elfcpp::R_X86_64_DTPMOD64:
case elfcpp::R_X86_64_TLSDESC:
gold_error(_("%s: unexpected reloc %u in object file"),
object->name().c_str(), r_type);
break;
// These are initial tls relocs, which are expected for global()
case elfcpp::R_X86_64_TLSGD: // Global-dynamic
case elfcpp::R_X86_64_GOTPC32_TLSDESC: // Global-dynamic (from ~oliva url)
case elfcpp::R_X86_64_TLSDESC_CALL:
case elfcpp::R_X86_64_TLSLD: // Local-dynamic
case elfcpp::R_X86_64_DTPOFF32:
case elfcpp::R_X86_64_DTPOFF64:
case elfcpp::R_X86_64_GOTTPOFF: // Initial-exec
case elfcpp::R_X86_64_TPOFF32: // Local-exec
{
// For the Initial-Exec model, we can treat undef symbols as final
// when building an executable.
const bool is_final = (gsym->final_value_is_known() ||
(r_type == elfcpp::R_X86_64_GOTTPOFF &&
gsym->is_undefined() &&
parameters->options().output_is_executable()));
const tls::Tls_optimization optimized_type
= Target_x86_64<size>::optimize_tls_reloc(is_final, r_type);
switch (r_type)
{
case elfcpp::R_X86_64_TLSGD: // General-dynamic
if (optimized_type == tls::TLSOPT_NONE)
{
// Create a pair of GOT entries for the module index and
// dtv-relative offset.
Output_data_got<64, false>* got
= target->got_section(symtab, layout);
got->add_global_pair_with_rel(gsym, GOT_TYPE_TLS_PAIR,
target->rela_dyn_section(layout),
elfcpp::R_X86_64_DTPMOD64,
elfcpp::R_X86_64_DTPOFF64);
}
else if (optimized_type == tls::TLSOPT_TO_IE)
{
// Create a GOT entry for the tp-relative offset.
Output_data_got<64, false>* got
= target->got_section(symtab, layout);
got->add_global_with_rel(gsym, GOT_TYPE_TLS_OFFSET,
target->rela_dyn_section(layout),
elfcpp::R_X86_64_TPOFF64);
}
else if (optimized_type != tls::TLSOPT_TO_LE)
unsupported_reloc_global(object, r_type, gsym);
break;
case elfcpp::R_X86_64_GOTPC32_TLSDESC:
target->define_tls_base_symbol(symtab, layout);
if (optimized_type == tls::TLSOPT_NONE)
{
// Create reserved PLT and GOT entries for the resolver.
target->reserve_tlsdesc_entries(symtab, layout);
// Create a double GOT entry with an R_X86_64_TLSDESC
// reloc. The R_X86_64_TLSDESC reloc is resolved
// lazily, so the GOT entry needs to be in an area in
// .got.plt, not .got. Call got_section to make sure
// the section has been created.
target->got_section(symtab, layout);
Output_data_got<64, false>* got = target->got_tlsdesc_section();
Reloc_section* rt = target->rela_tlsdesc_section(layout);
got->add_global_pair_with_rel(gsym, GOT_TYPE_TLS_DESC, rt,
elfcpp::R_X86_64_TLSDESC, 0);
}
else if (optimized_type == tls::TLSOPT_TO_IE)
{
// Create a GOT entry for the tp-relative offset.
Output_data_got<64, false>* got
= target->got_section(symtab, layout);
got->add_global_with_rel(gsym, GOT_TYPE_TLS_OFFSET,
target->rela_dyn_section(layout),
elfcpp::R_X86_64_TPOFF64);
}
else if (optimized_type != tls::TLSOPT_TO_LE)
unsupported_reloc_global(object, r_type, gsym);
break;
case elfcpp::R_X86_64_TLSDESC_CALL:
break;
case elfcpp::R_X86_64_TLSLD: // Local-dynamic
if (optimized_type == tls::TLSOPT_NONE)
{
// Create a GOT entry for the module index.
target->got_mod_index_entry(symtab, layout, object);
}
else if (optimized_type != tls::TLSOPT_TO_LE)
unsupported_reloc_global(object, r_type, gsym);
break;
case elfcpp::R_X86_64_DTPOFF32:
case elfcpp::R_X86_64_DTPOFF64:
break;
case elfcpp::R_X86_64_GOTTPOFF: // Initial-exec
layout->set_has_static_tls();
if (optimized_type == tls::TLSOPT_NONE)
{
// Create a GOT entry for the tp-relative offset.
Output_data_got<64, false>* got
= target->got_section(symtab, layout);
got->add_global_with_rel(gsym, GOT_TYPE_TLS_OFFSET,
target->rela_dyn_section(layout),
elfcpp::R_X86_64_TPOFF64);
}
else if (optimized_type != tls::TLSOPT_TO_LE)
unsupported_reloc_global(object, r_type, gsym);
break;
case elfcpp::R_X86_64_TPOFF32: // Local-exec
layout->set_has_static_tls();
if (parameters->options().shared())
unsupported_reloc_global(object, r_type, gsym);
break;
default:
gold_unreachable();
}
}
break;
case elfcpp::R_X86_64_SIZE32:
case elfcpp::R_X86_64_SIZE64:
default:
gold_error(_("%s: unsupported reloc %u against global symbol %s"),
object->name().c_str(), r_type,
gsym->demangled_name().c_str());
break;
}
}
template<int size>
void
Target_x86_64<size>::gc_process_relocs(Symbol_table* symtab,
Layout* layout,
Sized_relobj_file<size, false>* 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)
{
if (sh_type == elfcpp::SHT_REL)
{
return;
}
gold::gc_process_relocs<size, false, Target_x86_64<size>, elfcpp::SHT_RELA,
typename Target_x86_64<size>::Scan,
typename Target_x86_64<size>::Relocatable_size_for_reloc>(
symtab,
layout,
this,
object,
data_shndx,
prelocs,
reloc_count,
output_section,
needs_special_offset_handling,
local_symbol_count,
plocal_symbols);
}
// Scan relocations for a section.
template<int size>
void
Target_x86_64<size>::scan_relocs(Symbol_table* symtab,
Layout* layout,
Sized_relobj_file<size, false>* 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)
{
if (sh_type == elfcpp::SHT_REL)
{
gold_error(_("%s: unsupported REL reloc section"),
object->name().c_str());
return;
}
gold::scan_relocs<size, false, Target_x86_64<size>, elfcpp::SHT_RELA,
typename Target_x86_64<size>::Scan>(
symtab,
layout,
this,
object,
data_shndx,
prelocs,
reloc_count,
output_section,
needs_special_offset_handling,
local_symbol_count,
plocal_symbols);
}
// Finalize the sections.
template<int size>
void
Target_x86_64<size>::do_finalize_sections(
Layout* layout,
const Input_objects*,
Symbol_table* symtab)
{
const Reloc_section* rel_plt = (this->plt_ == NULL
? NULL
: this->plt_->rela_plt());
layout->add_target_dynamic_tags(false, this->got_plt_, rel_plt,
this->rela_dyn_, true, false);
// Fill in some more dynamic tags.
Output_data_dynamic* const odyn = layout->dynamic_data();
if (odyn != NULL)
{
if (this->plt_ != NULL
&& this->plt_->output_section() != NULL
&& this->plt_->has_tlsdesc_entry())
{
unsigned int plt_offset = this->plt_->get_tlsdesc_plt_offset();
unsigned int got_offset = this->plt_->get_tlsdesc_got_offset();
this->got_->finalize_data_size();
odyn->add_section_plus_offset(elfcpp::DT_TLSDESC_PLT,
this->plt_, plt_offset);
odyn->add_section_plus_offset(elfcpp::DT_TLSDESC_GOT,
this->got_, got_offset);
}
}
// Emit any relocs we saved in an attempt to avoid generating COPY
// relocs.
if (this->copy_relocs_.any_saved_relocs())
this->copy_relocs_.emit(this->rela_dyn_section(layout));
// Set the size of the _GLOBAL_OFFSET_TABLE_ symbol to the size of
// the .got.plt section.
Symbol* sym = this->global_offset_table_;
if (sym != NULL)
{
uint64_t data_size = this->got_plt_->current_data_size();
symtab->get_sized_symbol<size>(sym)->set_symsize(data_size);
}
if (parameters->doing_static_link()
&& (this->plt_ == NULL || !this->plt_->has_irelative_section()))
{
// If linking statically, make sure that the __rela_iplt symbols
// were defined if necessary, even if we didn't create a PLT.
static const Define_symbol_in_segment syms[] =
{
{
"__rela_iplt_start", // name
elfcpp::PT_LOAD, // segment_type
elfcpp::PF_W, // segment_flags_set
elfcpp::PF(0), // segment_flags_clear
0, // value
0, // size
elfcpp::STT_NOTYPE, // type
elfcpp::STB_GLOBAL, // binding
elfcpp::STV_HIDDEN, // visibility
0, // nonvis
Symbol::SEGMENT_START, // offset_from_base
true // only_if_ref
},
{
"__rela_iplt_end", // name
elfcpp::PT_LOAD, // segment_type
elfcpp::PF_W, // segment_flags_set
elfcpp::PF(0), // segment_flags_clear
0, // value
0, // size
elfcpp::STT_NOTYPE, // type
elfcpp::STB_GLOBAL, // binding
elfcpp::STV_HIDDEN, // visibility
0, // nonvis
Symbol::SEGMENT_START, // offset_from_base
true // only_if_ref
}
};
symtab->define_symbols(layout, 2, syms,
layout->script_options()->saw_sections_clause());
}
}
// Perform a relocation.
template<int size>
inline bool
Target_x86_64<size>::Relocate::relocate(
const Relocate_info<size, false>* relinfo,
Target_x86_64<size>* target,
Output_section*,
size_t relnum,
const elfcpp::Rela<size, false>& rela,
unsigned int r_type,
const Sized_symbol<size>* gsym,
const Symbol_value<size>* psymval,
unsigned char* view,
typename elfcpp::Elf_types<size>::Elf_Addr address,
section_size_type view_size)
{
if (this->skip_call_tls_get_addr_)
{
if ((r_type != elfcpp::R_X86_64_PLT32
&& r_type != elfcpp::R_X86_64_PLT32_BND
&& r_type != elfcpp::R_X86_64_PC32_BND
&& r_type != elfcpp::R_X86_64_PC32)
|| gsym == NULL
|| strcmp(gsym->name(), "__tls_get_addr") != 0)
{
gold_error_at_location(relinfo, relnum, rela.get_r_offset(),
_("missing expected TLS relocation"));
}
else
{
this->skip_call_tls_get_addr_ = false;
return false;
}
}
if (view == NULL)
return true;
const Sized_relobj_file<size, false>* object = relinfo->object;
// Pick the value to use for symbols defined in the PLT.
Symbol_value<size> symval;
if (gsym != NULL
&& gsym->use_plt_offset(Scan::get_reference_flags(r_type)))
{
symval.set_output_value(target->plt_address_for_global(gsym));
psymval = &symval;
}
else if (gsym == NULL && psymval->is_ifunc_symbol())
{
unsigned int r_sym = elfcpp::elf_r_sym<size>(rela.get_r_info());
if (object->local_has_plt_offset(r_sym))
{
symval.set_output_value(target->plt_address_for_local(object, r_sym));
psymval = &symval;
}
}
const elfcpp::Elf_Xword addend = rela.get_r_addend();
// Get the GOT offset if needed.
// The GOT pointer points to the end of the GOT section.
// We need to subtract the size of the GOT section to get
// the actual offset to use in the relocation.
bool have_got_offset = false;
// Since the actual offset is always negative, we use signed int to
// support 64-bit GOT relocations.
int got_offset = 0;
switch (r_type)
{
case elfcpp::R_X86_64_GOT32:
case elfcpp::R_X86_64_GOT64:
case elfcpp::R_X86_64_GOTPLT64:
case elfcpp::R_X86_64_GOTPCREL:
case elfcpp::R_X86_64_GOTPCREL64:
if (gsym != NULL)
{
gold_assert(gsym->has_got_offset(GOT_TYPE_STANDARD));
got_offset = gsym->got_offset(GOT_TYPE_STANDARD) - target->got_size();
}
else
{
unsigned int r_sym = elfcpp::elf_r_sym<size>(rela.get_r_info());
gold_assert(object->local_has_got_offset(r_sym, GOT_TYPE_STANDARD));
got_offset = (object->local_got_offset(r_sym, GOT_TYPE_STANDARD)
- target->got_size());
}
have_got_offset = true;
break;
default:
break;
}
switch (r_type)
{
case elfcpp::R_X86_64_NONE:
case elfcpp::R_X86_64_GNU_VTINHERIT:
case elfcpp::R_X86_64_GNU_VTENTRY:
break;
case elfcpp::R_X86_64_64:
Relocate_functions<size, false>::rela64(view, object, psymval, addend);
break;
case elfcpp::R_X86_64_PC64:
Relocate_functions<size, false>::pcrela64(view, object, psymval, addend,
address);
break;
case elfcpp::R_X86_64_32:
// FIXME: we need to verify that value + addend fits into 32 bits:
// uint64_t x = value + addend;
// x == static_cast<uint64_t>(static_cast<uint32_t>(x))
// Likewise for other <=32-bit relocations (but see R_X86_64_32S).
Relocate_functions<size, false>::rela32(view, object, psymval, addend);
break;
case elfcpp::R_X86_64_32S:
// FIXME: we need to verify that value + addend fits into 32 bits:
// int64_t x = value + addend; // note this quantity is signed!
// x == static_cast<int64_t>(static_cast<int32_t>(x))
Relocate_functions<size, false>::rela32(view, object, psymval, addend);
break;
case elfcpp::R_X86_64_PC32:
case elfcpp::R_X86_64_PC32_BND:
Relocate_functions<size, false>::pcrela32(view, object, psymval, addend,
address);
break;
case elfcpp::R_X86_64_16:
Relocate_functions<size, false>::rela16(view, object, psymval, addend);
break;
case elfcpp::R_X86_64_PC16:
Relocate_functions<size, false>::pcrela16(view, object, psymval, addend,
address);
break;
case elfcpp::R_X86_64_8:
Relocate_functions<size, false>::rela8(view, object, psymval, addend);
break;
case elfcpp::R_X86_64_PC8:
Relocate_functions<size, false>::pcrela8(view, object, psymval, addend,
address);
break;
case elfcpp::R_X86_64_PLT32:
case elfcpp::R_X86_64_PLT32_BND:
gold_assert(gsym == NULL
|| gsym->has_plt_offset()
|| gsym->final_value_is_known()
|| (gsym->is_defined()
&& !gsym->is_from_dynobj()
&& !gsym->is_preemptible()));
// Note: while this code looks the same as for R_X86_64_PC32, it
// behaves differently because psymval was set to point to
// the PLT entry, rather than the symbol, in Scan::global().
Relocate_functions<size, false>::pcrela32(view, object, psymval, addend,
address);
break;
case elfcpp::R_X86_64_PLTOFF64:
{
gold_assert(gsym);
gold_assert(gsym->has_plt_offset()
|| gsym->final_value_is_known());
typename elfcpp::Elf_types<size>::Elf_Addr got_address;
// This is the address of GLOBAL_OFFSET_TABLE.
got_address = target->got_plt_section()->address();
Relocate_functions<size, false>::rela64(view, object, psymval,
addend - got_address);
}
break;
case elfcpp::R_X86_64_GOT32:
gold_assert(have_got_offset);
Relocate_functions<size, false>::rela32(view, got_offset, addend);
break;
case elfcpp::R_X86_64_GOTPC32:
{
gold_assert(gsym);
typename elfcpp::Elf_types<size>::Elf_Addr value;
value = target->got_plt_section()->address();
Relocate_functions<size, false>::pcrela32(view, value, addend, address);
}
break;
case elfcpp::R_X86_64_GOT64:
case elfcpp::R_X86_64_GOTPLT64:
// R_X86_64_GOTPLT64 is obsolete and treated the the same as
// GOT64.
gold_assert(have_got_offset);
Relocate_functions<size, false>::rela64(view, got_offset, addend);
break;
case elfcpp::R_X86_64_GOTPC64:
{
gold_assert(gsym);
typename elfcpp::Elf_types<size>::Elf_Addr value;
value = target->got_plt_section()->address();
Relocate_functions<size, false>::pcrela64(view, value, addend, address);
}
break;
case elfcpp::R_X86_64_GOTOFF64:
{
typename elfcpp::Elf_types<size>::Elf_Addr value;
value = (psymval->value(object, 0)
- target->got_plt_section()->address());
Relocate_functions<size, false>::rela64(view, value, addend);
}
break;
case elfcpp::R_X86_64_GOTPCREL:
{
gold_assert(have_got_offset);
typename elfcpp::Elf_types<size>::Elf_Addr value;
value = target->got_plt_section()->address() + got_offset;
Relocate_functions<size, false>::pcrela32(view, value, addend, address);
}
break;
case elfcpp::R_X86_64_GOTPCREL64:
{
gold_assert(have_got_offset);
typename elfcpp::Elf_types<size>::Elf_Addr value;
value = target->got_plt_section()->address() + got_offset;
Relocate_functions<size, false>::pcrela64(view, value, addend, address);
}
break;
case elfcpp::R_X86_64_COPY:
case elfcpp::R_X86_64_GLOB_DAT:
case elfcpp::R_X86_64_JUMP_SLOT:
case elfcpp::R_X86_64_RELATIVE:
case elfcpp::R_X86_64_IRELATIVE:
// These are outstanding tls relocs, which are unexpected when linking
case elfcpp::R_X86_64_TPOFF64:
case elfcpp::R_X86_64_DTPMOD64:
case elfcpp::R_X86_64_TLSDESC:
gold_error_at_location(relinfo, relnum, rela.get_r_offset(),
_("unexpected reloc %u in object file"),
r_type);
break;
// These are initial tls relocs, which are expected when linking
case elfcpp::R_X86_64_TLSGD: // Global-dynamic
case elfcpp::R_X86_64_GOTPC32_TLSDESC: // Global-dynamic (from ~oliva url)
case elfcpp::R_X86_64_TLSDESC_CALL:
case elfcpp::R_X86_64_TLSLD: // Local-dynamic
case elfcpp::R_X86_64_DTPOFF32:
case elfcpp::R_X86_64_DTPOFF64:
case elfcpp::R_X86_64_GOTTPOFF: // Initial-exec
case elfcpp::R_X86_64_TPOFF32: // Local-exec
this->relocate_tls(relinfo, target, relnum, rela, r_type, gsym, psymval,
view, address, view_size);
break;
case elfcpp::R_X86_64_SIZE32:
case elfcpp::R_X86_64_SIZE64:
default:
gold_error_at_location(relinfo, relnum, rela.get_r_offset(),
_("unsupported reloc %u"),
r_type);
break;
}
return true;
}
// Perform a TLS relocation.
template<int size>
inline void
Target_x86_64<size>::Relocate::relocate_tls(
const Relocate_info<size, false>* relinfo,
Target_x86_64<size>* target,
size_t relnum,
const elfcpp::Rela<size, false>& rela,
unsigned int r_type,
const Sized_symbol<size>* gsym,
const Symbol_value<size>* psymval,
unsigned char* view,
typename elfcpp::Elf_types<size>::Elf_Addr address,
section_size_type view_size)
{
Output_segment* tls_segment = relinfo->layout->tls_segment();
const Sized_relobj_file<size, false>* object = relinfo->object;
const elfcpp::Elf_Xword addend = rela.get_r_addend();
elfcpp::Shdr<size, false> data_shdr(relinfo->data_shdr);
bool is_executable = (data_shdr.get_sh_flags() & elfcpp::SHF_EXECINSTR) != 0;
typename elfcpp::Elf_types<size>::Elf_Addr value = psymval->value(relinfo->object, 0);
const bool is_final = (gsym == NULL
? !parameters->options().shared()
: gsym->final_value_is_known());
tls::Tls_optimization optimized_type
= Target_x86_64<size>::optimize_tls_reloc(is_final, r_type);
switch (r_type)
{
case elfcpp::R_X86_64_TLSGD: // Global-dynamic
if (!is_executable && optimized_type == tls::TLSOPT_TO_LE)
{
// If this code sequence is used in a non-executable section,
// we will not optimize the R_X86_64_DTPOFF32/64 relocation,
// on the assumption that it's being used by itself in a debug
// section. Therefore, in the unlikely event that the code
// sequence appears in a non-executable section, we simply
// leave it unoptimized.
optimized_type = tls::TLSOPT_NONE;
}
if (optimized_type == tls::TLSOPT_TO_LE)
{
if (tls_segment == NULL)
{
gold_assert(parameters->errors()->error_count() > 0
|| issue_undefined_symbol_error(gsym));
return;
}
this->tls_gd_to_le(relinfo, relnum, tls_segment,
rela, r_type, value, view,
view_size);
break;
}
else
{
unsigned int got_type = (optimized_type == tls::TLSOPT_TO_IE
? GOT_TYPE_TLS_OFFSET
: GOT_TYPE_TLS_PAIR);
unsigned int got_offset;
if (gsym != NULL)
{
gold_assert(gsym->has_got_offset(got_type));
got_offset = gsym->got_offset(got_type) - target->got_size();
}
else
{
unsigned int r_sym = elfcpp::elf_r_sym<size>(rela.get_r_info());
gold_assert(object->local_has_got_offset(r_sym, got_type));
got_offset = (object->local_got_offset(r_sym, got_type)
- target->got_size());
}
if (optimized_type == tls::TLSOPT_TO_IE)
{
value = target->got_plt_section()->address() + got_offset;
this->tls_gd_to_ie(relinfo, relnum, tls_segment, rela, r_type,
value, view, address, view_size);
break;
}
else if (optimized_type == tls::TLSOPT_NONE)
{
// Relocate the field with the offset of the pair of GOT
// entries.
value = target->got_plt_section()->address() + got_offset;
Relocate_functions<size, false>::pcrela32(view, value, addend,
address);
break;
}
}
gold_error_at_location(relinfo, relnum, rela.get_r_offset(),
_("unsupported reloc %u"), r_type);
break;
case elfcpp::R_X86_64_GOTPC32_TLSDESC: // Global-dynamic (from ~oliva url)
case elfcpp::R_X86_64_TLSDESC_CALL:
if (!is_executable && optimized_type == tls::TLSOPT_TO_LE)
{
// See above comment for R_X86_64_TLSGD.
optimized_type = tls::TLSOPT_NONE;
}
if (optimized_type == tls::TLSOPT_TO_LE)
{
if (tls_segment == NULL)
{
gold_assert(parameters->errors()->error_count() > 0
|| issue_undefined_symbol_error(gsym));
return;
}
this->tls_desc_gd_to_le(relinfo, relnum, tls_segment,
rela, r_type, value, view,
view_size);
break;
}
else
{
unsigned int got_type = (optimized_type == tls::TLSOPT_TO_IE
? GOT_TYPE_TLS_OFFSET
: GOT_TYPE_TLS_DESC);
unsigned int got_offset = 0;
if (r_type == elfcpp::R_X86_64_GOTPC32_TLSDESC
&& optimized_type == tls::TLSOPT_NONE)
{
// We created GOT entries in the .got.tlsdesc portion of
// the .got.plt section, but the offset stored in the
// symbol is the offset within .got.tlsdesc.
got_offset = (target->got_size()
+ target->got_plt_section()->data_size());
}
if (gsym != NULL)
{
gold_assert(gsym->has_got_offset(got_type));
got_offset += gsym->got_offset(got_type) - target->got_size();
}
else
{
unsigned int r_sym = elfcpp::elf_r_sym<size>(rela.get_r_info());
gold_assert(object->local_has_got_offset(r_sym, got_type));
got_offset += (object->local_got_offset(r_sym, got_type)
- target->got_size());
}
if (optimized_type == tls::TLSOPT_TO_IE)
{
if (tls_segment == NULL)
{
gold_assert(parameters->errors()->error_count() > 0
|| issue_undefined_symbol_error(gsym));
return;
}
value = target->got_plt_section()->address() + got_offset;
this->tls_desc_gd_to_ie(relinfo, relnum, tls_segment,
rela, r_type, value, view, address,
view_size);
break;
}
else if (optimized_type == tls::TLSOPT_NONE)
{
if (r_type == elfcpp::R_X86_64_GOTPC32_TLSDESC)
{
// Relocate the field with the offset of the pair of GOT
// entries.
value = target->got_plt_section()->address() + got_offset;
Relocate_functions<size, false>::pcrela32(view, value, addend,
address);
}
break;
}
}
gold_error_at_location(relinfo, relnum, rela.get_r_offset(),
_("unsupported reloc %u"), r_type);
break;
case elfcpp::R_X86_64_TLSLD: // Local-dynamic
if (!is_executable && optimized_type == tls::TLSOPT_TO_LE)
{
// See above comment for R_X86_64_TLSGD.
optimized_type = tls::TLSOPT_NONE;
}
if (optimized_type == tls::TLSOPT_TO_LE)
{
if (tls_segment == NULL)
{
gold_assert(parameters->errors()->error_count() > 0
|| issue_undefined_symbol_error(gsym));
return;
}
this->tls_ld_to_le(relinfo, relnum, tls_segment, rela, r_type,
value, view, view_size);
break;
}
else if (optimized_type == tls::TLSOPT_NONE)
{
// Relocate the field with the offset of the GOT entry for
// the module index.
unsigned int got_offset;
got_offset = (target->got_mod_index_entry(NULL, NULL, NULL)
- target->got_size());
value = target->got_plt_section()->address() + got_offset;
Relocate_functions<size, false>::pcrela32(view, value, addend,
address);
break;
}
gold_error_at_location(relinfo, relnum, rela.get_r_offset(),
_("unsupported reloc %u"), r_type);
break;
case elfcpp::R_X86_64_DTPOFF32:
// This relocation type is used in debugging information.
// In that case we need to not optimize the value. If the
// section is not executable, then we assume we should not
// optimize this reloc. See comments above for R_X86_64_TLSGD,
// R_X86_64_GOTPC32_TLSDESC, R_X86_64_TLSDESC_CALL, and
// R_X86_64_TLSLD.
if (optimized_type == tls::TLSOPT_TO_LE && is_executable)
{
if (tls_segment == NULL)
{
gold_assert(parameters->errors()->error_count() > 0
|| issue_undefined_symbol_error(gsym));
return;
}
value -= tls_segment->memsz();
}
Relocate_functions<size, false>::rela32(view, value, addend);
break;
case elfcpp::R_X86_64_DTPOFF64:
// See R_X86_64_DTPOFF32, just above, for why we check for is_executable.
if (optimized_type == tls::TLSOPT_TO_LE && is_executable)
{
if (tls_segment == NULL)
{
gold_assert(parameters->errors()->error_count() > 0
|| issue_undefined_symbol_error(gsym));
return;
}
value -= tls_segment->memsz();
}
Relocate_functions<size, false>::rela64(view, value, addend);
break;
case elfcpp::R_X86_64_GOTTPOFF: // Initial-exec
if (gsym != NULL
&& gsym->is_undefined()
&& parameters->options().output_is_executable())
{
Target_x86_64<size>::Relocate::tls_ie_to_le(relinfo, relnum,
NULL, rela,
r_type, value, view,
view_size);
break;
}
else if (optimized_type == tls::TLSOPT_TO_LE)
{
if (tls_segment == NULL)
{
gold_assert(parameters->errors()->error_count() > 0
|| issue_undefined_symbol_error(gsym));
return;
}
Target_x86_64<size>::Relocate::tls_ie_to_le(relinfo, relnum,
tls_segment, rela,
r_type, value, view,
view_size);
break;
}
else if (optimized_type == tls::TLSOPT_NONE)
{
// Relocate the field with the offset of the GOT entry for
// the tp-relative offset of the symbol.
unsigned int got_offset;
if (gsym != NULL)
{
gold_assert(gsym->has_got_offset(GOT_TYPE_TLS_OFFSET));
got_offset = (gsym->got_offset(GOT_TYPE_TLS_OFFSET)
- target->got_size());
}
else
{
unsigned int r_sym = elfcpp::elf_r_sym<size>(rela.get_r_info());
gold_assert(object->local_has_got_offset(r_sym,
GOT_TYPE_TLS_OFFSET));
got_offset = (object->local_got_offset(r_sym, GOT_TYPE_TLS_OFFSET)
- target->got_size());
}
value = target->got_plt_section()->address() + got_offset;
Relocate_functions<size, false>::pcrela32(view, value, addend,
address);
break;
}
gold_error_at_location(relinfo, relnum, rela.get_r_offset(),
_("unsupported reloc type %u"),
r_type);
break;
case elfcpp::R_X86_64_TPOFF32: // Local-exec
if (tls_segment == NULL)
{
gold_assert(parameters->errors()->error_count() > 0
|| issue_undefined_symbol_error(gsym));
return;
}
value -= tls_segment->memsz();
Relocate_functions<size, false>::rela32(view, value, addend);
break;
}
}
// Do a relocation in which we convert a TLS General-Dynamic to an
// Initial-Exec.
template<int size>
inline void
Target_x86_64<size>::Relocate::tls_gd_to_ie(
const Relocate_info<size, false>* relinfo,
size_t relnum,
Output_segment*,
const elfcpp::Rela<size, false>& rela,
unsigned int,
typename elfcpp::Elf_types<size>::Elf_Addr value,
unsigned char* view,
typename elfcpp::Elf_types<size>::Elf_Addr address,
section_size_type view_size)
{
// For SIZE == 64:
// .byte 0x66; leaq foo@tlsgd(%rip),%rdi;
// .word 0x6666; rex64; call __tls_get_addr
// ==> movq %fs:0,%rax; addq x@gottpoff(%rip),%rax
// For SIZE == 32:
// leaq foo@tlsgd(%rip),%rdi;
// .word 0x6666; rex64; call __tls_get_addr
// ==> movl %fs:0,%eax; addq x@gottpoff(%rip),%rax
tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, 12);
tls::check_tls(relinfo, relnum, rela.get_r_offset(),
(memcmp(view + 4, "\x66\x66\x48\xe8", 4) == 0));
if (size == 64)
{
tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size,
-4);
tls::check_tls(relinfo, relnum, rela.get_r_offset(),
(memcmp(view - 4, "\x66\x48\x8d\x3d", 4) == 0));
memcpy(view - 4, "\x64\x48\x8b\x04\x25\0\0\0\0\x48\x03\x05\0\0\0\0",
16);
}
else
{
tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size,
-3);
tls::check_tls(relinfo, relnum, rela.get_r_offset(),
(memcmp(view - 3, "\x48\x8d\x3d", 3) == 0));
memcpy(view - 3, "\x64\x8b\x04\x25\0\0\0\0\x48\x03\x05\0\0\0\0",
15);
}
const elfcpp::Elf_Xword addend = rela.get_r_addend();
Relocate_functions<size, false>::pcrela32(view + 8, value, addend - 8,
address);
// The next reloc should be a PLT32 reloc against __tls_get_addr.
// We can skip it.
this->skip_call_tls_get_addr_ = true;
}
// Do a relocation in which we convert a TLS General-Dynamic to a
// Local-Exec.
template<int size>
inline void
Target_x86_64<size>::Relocate::tls_gd_to_le(
const Relocate_info<size, false>* relinfo,
size_t relnum,
Output_segment* tls_segment,
const elfcpp::Rela<size, false>& rela,
unsigned int,
typename elfcpp::Elf_types<size>::Elf_Addr value,
unsigned char* view,
section_size_type view_size)
{
// For SIZE == 64:
// .byte 0x66; leaq foo@tlsgd(%rip),%rdi;
// .word 0x6666; rex64; call __tls_get_addr
// ==> movq %fs:0,%rax; leaq x@tpoff(%rax),%rax
// For SIZE == 32:
// leaq foo@tlsgd(%rip),%rdi;
// .word 0x6666; rex64; call __tls_get_addr
// ==> movl %fs:0,%eax; leaq x@tpoff(%rax),%rax
tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, 12);
tls::check_tls(relinfo, relnum, rela.get_r_offset(),
(memcmp(view + 4, "\x66\x66\x48\xe8", 4) == 0));
if (size == 64)
{
tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size,
-4);
tls::check_tls(relinfo, relnum, rela.get_r_offset(),
(memcmp(view - 4, "\x66\x48\x8d\x3d", 4) == 0));
memcpy(view - 4, "\x64\x48\x8b\x04\x25\0\0\0\0\x48\x8d\x80\0\0\0\0",
16);
}
else
{
tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size,
-3);
tls::check_tls(relinfo, relnum, rela.get_r_offset(),
(memcmp(view - 3, "\x48\x8d\x3d", 3) == 0));
memcpy(view - 3, "\x64\x8b\x04\x25\0\0\0\0\x48\x8d\x80\0\0\0\0",
15);
}
value -= tls_segment->memsz();
Relocate_functions<size, false>::rela32(view + 8, value, 0);
// The next reloc should be a PLT32 reloc against __tls_get_addr.
// We can skip it.
this->skip_call_tls_get_addr_ = true;
}
// Do a TLSDESC-style General-Dynamic to Initial-Exec transition.
template<int size>
inline void
Target_x86_64<size>::Relocate::tls_desc_gd_to_ie(
const Relocate_info<size, false>* relinfo,
size_t relnum,
Output_segment*,
const elfcpp::Rela<size, false>& rela,
unsigned int r_type,
typename elfcpp::Elf_types<size>::Elf_Addr value,
unsigned char* view,
typename elfcpp::Elf_types<size>::Elf_Addr address,
section_size_type view_size)
{
if (r_type == elfcpp::R_X86_64_GOTPC32_TLSDESC)
{
// leaq foo@tlsdesc(%rip), %rax
// ==> movq foo@gottpoff(%rip), %rax
tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, -3);
tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, 4);
tls::check_tls(relinfo, relnum, rela.get_r_offset(),
view[-3] == 0x48 && view[-2] == 0x8d && view[-1] == 0x05);
view[-2] = 0x8b;
const elfcpp::Elf_Xword addend = rela.get_r_addend();
Relocate_functions<size, false>::pcrela32(view, value, addend, address);
}
else
{
// call *foo@tlscall(%rax)
// ==> nop; nop
gold_assert(r_type == elfcpp::R_X86_64_TLSDESC_CALL);
tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, 2);
tls::check_tls(relinfo, relnum, rela.get_r_offset(),
view[0] == 0xff && view[1] == 0x10);
view[0] = 0x66;
view[1] = 0x90;
}
}
// Do a TLSDESC-style General-Dynamic to Local-Exec transition.
template<int size>
inline void
Target_x86_64<size>::Relocate::tls_desc_gd_to_le(
const Relocate_info<size, false>* relinfo,
size_t relnum,
Output_segment* tls_segment,
const elfcpp::Rela<size, false>& rela,
unsigned int r_type,
typename elfcpp::Elf_types<size>::Elf_Addr value,
unsigned char* view,
section_size_type view_size)
{
if (r_type == elfcpp::R_X86_64_GOTPC32_TLSDESC)
{
// leaq foo@tlsdesc(%rip), %rax
// ==> movq foo@tpoff, %rax
tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, -3);
tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, 4);
tls::check_tls(relinfo, relnum, rela.get_r_offset(),
view[-3] == 0x48 && view[-2] == 0x8d && view[-1] == 0x05);
view[-2] = 0xc7;
view[-1] = 0xc0;
value -= tls_segment->memsz();
Relocate_functions<size, false>::rela32(view, value, 0);
}
else
{
// call *foo@tlscall(%rax)
// ==> nop; nop
gold_assert(r_type == elfcpp::R_X86_64_TLSDESC_CALL);
tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, 2);
tls::check_tls(relinfo, relnum, rela.get_r_offset(),
view[0] == 0xff && view[1] == 0x10);
view[0] = 0x66;
view[1] = 0x90;
}
}
template<int size>
inline void
Target_x86_64<size>::Relocate::tls_ld_to_le(
const Relocate_info<size, false>* relinfo,
size_t relnum,
Output_segment*,
const elfcpp::Rela<size, false>& rela,
unsigned int,
typename elfcpp::Elf_types<size>::Elf_Addr,
unsigned char* view,
section_size_type view_size)
{
// leaq foo@tlsld(%rip),%rdi; call __tls_get_addr@plt;
// For SIZE == 64:
// ... leq foo@dtpoff(%rax),%reg
// ==> .word 0x6666; .byte 0x66; movq %fs:0,%rax ... leaq x@tpoff(%rax),%rdx
// For SIZE == 32:
// ... leq foo@dtpoff(%rax),%reg
// ==> nopl 0x0(%rax); movl %fs:0,%eax ... leaq x@tpoff(%rax),%rdx
tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, -3);
tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, 9);
tls::check_tls(relinfo, relnum, rela.get_r_offset(),
view[-3] == 0x48 && view[-2] == 0x8d && view[-1] == 0x3d);
tls::check_tls(relinfo, relnum, rela.get_r_offset(), view[4] == 0xe8);
if (size == 64)
memcpy(view - 3, "\x66\x66\x66\x64\x48\x8b\x04\x25\0\0\0\0", 12);
else
memcpy(view - 3, "\x0f\x1f\x40\x00\x64\x8b\x04\x25\0\0\0\0", 12);
// The next reloc should be a PLT32 reloc against __tls_get_addr.
// We can skip it.
this->skip_call_tls_get_addr_ = true;
}
// Do a relocation in which we convert a TLS Initial-Exec to a
// Local-Exec.
template<int size>
inline void
Target_x86_64<size>::Relocate::tls_ie_to_le(
const Relocate_info<size, false>* relinfo,
size_t relnum,
Output_segment* tls_segment,
const elfcpp::Rela<size, false>& rela,
unsigned int,
typename elfcpp::Elf_types<size>::Elf_Addr value,
unsigned char* view,
section_size_type view_size)
{
// We need to examine the opcodes to figure out which instruction we
// are looking at.
// movq foo@gottpoff(%rip),%reg ==> movq $YY,%reg
// addq foo@gottpoff(%rip),%reg ==> addq $YY,%reg
tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, -3);
tls::check_range(relinfo, relnum, rela.get_r_offset(), view_size, 4);
unsigned char op1 = view[-3];
unsigned char op2 = view[-2];
unsigned char op3 = view[-1];
unsigned char reg = op3 >> 3;
if (op2 == 0x8b)
{
// movq
if (op1 == 0x4c)
view[-3] = 0x49;
else if (size == 32 && op1 == 0x44)
view[-3] = 0x41;
view[-2] = 0xc7;
view[-1] = 0xc0 | reg;
}
else if (reg == 4)
{
// Special handling for %rsp.
if (op1 == 0x4c)
view[-3] = 0x49;
else if (size == 32 && op1 == 0x44)
view[-3] = 0x41;
view[-2] = 0x81;
view[-1] = 0xc0 | reg;
}
else
{
// addq
if (op1 == 0x4c)
view[-3] = 0x4d;
else if (size == 32 && op1 == 0x44)
view[-3] = 0x45;
view[-2] = 0x8d;
view[-1] = 0x80 | reg | (reg << 3);
}
if (tls_segment != NULL)
value -= tls_segment->memsz();
Relocate_functions<size, false>::rela32(view, value, 0);
}
// Relocate section data.
template<int size>
void
Target_x86_64<size>::relocate_section(
const Relocate_info<size, false>* relinfo,
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 address,
section_size_type view_size,
const Reloc_symbol_changes* reloc_symbol_changes)
{
gold_assert(sh_type == elfcpp::SHT_RELA);
gold::relocate_section<size, false, Target_x86_64<size>, elfcpp::SHT_RELA,
typename Target_x86_64<size>::Relocate,
gold::Default_comdat_behavior>(
relinfo,
this,
prelocs,
reloc_count,
output_section,
needs_special_offset_handling,
view,
address,
view_size,
reloc_symbol_changes);
}
// Apply an incremental relocation. Incremental relocations always refer
// to global symbols.
template<int size>
void
Target_x86_64<size>::apply_relocation(
const Relocate_info<size, false>* 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::apply_relocation<size, false, Target_x86_64<size>,
typename Target_x86_64<size>::Relocate>(
relinfo,
this,
r_offset,
r_type,
r_addend,
gsym,
view,
address,
view_size);
}
// Return the size of a relocation while scanning during a relocatable
// link.
template<int size>
unsigned int
Target_x86_64<size>::Relocatable_size_for_reloc::get_size_for_reloc(
unsigned int r_type,
Relobj* object)
{
switch (r_type)
{
case elfcpp::R_X86_64_NONE:
case elfcpp::R_X86_64_GNU_VTINHERIT:
case elfcpp::R_X86_64_GNU_VTENTRY:
case elfcpp::R_X86_64_TLSGD: // Global-dynamic
case elfcpp::R_X86_64_GOTPC32_TLSDESC: // Global-dynamic (from ~oliva url)
case elfcpp::R_X86_64_TLSDESC_CALL:
case elfcpp::R_X86_64_TLSLD: // Local-dynamic
case elfcpp::R_X86_64_DTPOFF32:
case elfcpp::R_X86_64_DTPOFF64:
case elfcpp::R_X86_64_GOTTPOFF: // Initial-exec
case elfcpp::R_X86_64_TPOFF32: // Local-exec
return 0;
case elfcpp::R_X86_64_64:
case elfcpp::R_X86_64_PC64:
case elfcpp::R_X86_64_GOTOFF64:
case elfcpp::R_X86_64_GOTPC64:
case elfcpp::R_X86_64_PLTOFF64:
case elfcpp::R_X86_64_GOT64:
case elfcpp::R_X86_64_GOTPCREL64:
case elfcpp::R_X86_64_GOTPCREL:
case elfcpp::R_X86_64_GOTPLT64:
return 8;
case elfcpp::R_X86_64_32:
case elfcpp::R_X86_64_32S:
case elfcpp::R_X86_64_PC32:
case elfcpp::R_X86_64_PC32_BND:
case elfcpp::R_X86_64_PLT32:
case elfcpp::R_X86_64_PLT32_BND:
case elfcpp::R_X86_64_GOTPC32:
case elfcpp::R_X86_64_GOT32:
return 4;
case elfcpp::R_X86_64_16:
case elfcpp::R_X86_64_PC16:
return 2;
case elfcpp::R_X86_64_8:
case elfcpp::R_X86_64_PC8:
return 1;
case elfcpp::R_X86_64_COPY:
case elfcpp::R_X86_64_GLOB_DAT:
case elfcpp::R_X86_64_JUMP_SLOT:
case elfcpp::R_X86_64_RELATIVE:
case elfcpp::R_X86_64_IRELATIVE:
// These are outstanding tls relocs, which are unexpected when linking
case elfcpp::R_X86_64_TPOFF64:
case elfcpp::R_X86_64_DTPMOD64:
case elfcpp::R_X86_64_TLSDESC:
object->error(_("unexpected reloc %u in object file"), r_type);
return 0;
case elfcpp::R_X86_64_SIZE32:
case elfcpp::R_X86_64_SIZE64:
default:
object->error(_("unsupported reloc %u against local symbol"), r_type);
return 0;
}
}
// Scan the relocs during a relocatable link.
template<int size>
void
Target_x86_64<size>::scan_relocatable_relocs(
Symbol_table* symtab,
Layout* layout,
Sized_relobj_file<size, false>* 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* rr)
{
gold_assert(sh_type == elfcpp::SHT_RELA);
typedef gold::Default_scan_relocatable_relocs<elfcpp::SHT_RELA,
Relocatable_size_for_reloc> Scan_relocatable_relocs;
gold::scan_relocatable_relocs<size, false, elfcpp::SHT_RELA,
Scan_relocatable_relocs>(
symtab,
layout,
object,
data_shndx,
prelocs,
reloc_count,
output_section,
needs_special_offset_handling,
local_symbol_count,
plocal_symbols,
rr);
}
// Relocate a section during a relocatable link.
template<int size>
void
Target_x86_64<size>::relocate_relocs(
const Relocate_info<size, false>* relinfo,
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,
const Relocatable_relocs* rr,
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)
{
gold_assert(sh_type == elfcpp::SHT_RELA);
gold::relocate_relocs<size, false, elfcpp::SHT_RELA>(
relinfo,
prelocs,
reloc_count,
output_section,
offset_in_output_section,
rr,
view,
view_address,
view_size,
reloc_view,
reloc_view_size);
}
// Return the value to use for a dynamic which requires special
// treatment. This is how we support equality comparisons of function
// pointers across shared library boundaries, as described in the
// processor specific ABI supplement.
template<int size>
uint64_t
Target_x86_64<size>::do_dynsym_value(const Symbol* gsym) const
{
gold_assert(gsym->is_from_dynobj() && gsym->has_plt_offset());
return this->plt_address_for_global(gsym);
}
// Return a string used to fill a code section with nops to take up
// the specified length.
template<int size>
std::string
Target_x86_64<size>::do_code_fill(section_size_type length) const
{
if (length >= 16)
{
// Build a jmpq instruction to skip over the bytes.
unsigned char jmp[5];
jmp[0] = 0xe9;
elfcpp::Swap_unaligned<32, false>::writeval(jmp + 1, length - 5);
return (std::string(reinterpret_cast<char*>(&jmp[0]), 5)
+ std::string(length - 5, static_cast<char>(0x90)));
}
// Nop sequences of various lengths.
const char nop1[1] = { '\x90' }; // nop
const char nop2[2] = { '\x66', '\x90' }; // xchg %ax %ax
const char nop3[3] = { '\x0f', '\x1f', '\x00' }; // nop (%rax)
const char nop4[4] = { '\x0f', '\x1f', '\x40', // nop 0(%rax)
'\x00'};
const char nop5[5] = { '\x0f', '\x1f', '\x44', // nop 0(%rax,%rax,1)
'\x00', '\x00' };
const char nop6[6] = { '\x66', '\x0f', '\x1f', // nopw 0(%rax,%rax,1)
'\x44', '\x00', '\x00' };
const char nop7[7] = { '\x0f', '\x1f', '\x80', // nopl 0L(%rax)
'\x00', '\x00', '\x00',
'\x00' };
const char nop8[8] = { '\x0f', '\x1f', '\x84', // nopl 0L(%rax,%rax,1)
'\x00', '\x00', '\x00',
'\x00', '\x00' };
const char nop9[9] = { '\x66', '\x0f', '\x1f', // nopw 0L(%rax,%rax,1)
'\x84', '\x00', '\x00',
'\x00', '\x00', '\x00' };
const char nop10[10] = { '\x66', '\x2e', '\x0f', // nopw %cs:0L(%rax,%rax,1)
'\x1f', '\x84', '\x00',
'\x00', '\x00', '\x00',
'\x00' };
const char nop11[11] = { '\x66', '\x66', '\x2e', // data16
'\x0f', '\x1f', '\x84', // nopw %cs:0L(%rax,%rax,1)
'\x00', '\x00', '\x00',
'\x00', '\x00' };
const char nop12[12] = { '\x66', '\x66', '\x66', // data16; data16
'\x2e', '\x0f', '\x1f', // nopw %cs:0L(%rax,%rax,1)
'\x84', '\x00', '\x00',
'\x00', '\x00', '\x00' };
const char nop13[13] = { '\x66', '\x66', '\x66', // data16; data16; data16
'\x66', '\x2e', '\x0f', // nopw %cs:0L(%rax,%rax,1)
'\x1f', '\x84', '\x00',
'\x00', '\x00', '\x00',
'\x00' };
const char nop14[14] = { '\x66', '\x66', '\x66', // data16; data16; data16
'\x66', '\x66', '\x2e', // data16
'\x0f', '\x1f', '\x84', // nopw %cs:0L(%rax,%rax,1)
'\x00', '\x00', '\x00',
'\x00', '\x00' };
const char nop15[15] = { '\x66', '\x66', '\x66', // data16; data16; data16
'\x66', '\x66', '\x66', // data16; data16
'\x2e', '\x0f', '\x1f', // nopw %cs:0L(%rax,%rax,1)
'\x84', '\x00', '\x00',
'\x00', '\x00', '\x00' };
const char* nops[16] = {
NULL,
nop1, nop2, nop3, nop4, nop5, nop6, nop7,
nop8, nop9, nop10, nop11, nop12, nop13, nop14, nop15
};
return std::string(nops[length], length);
}
// Return the addend to use for a target specific relocation. The
// only target specific relocation is R_X86_64_TLSDESC for a local
// symbol. We want to set the addend is the offset of the local
// symbol in the TLS segment.
template<int size>
uint64_t
Target_x86_64<size>::do_reloc_addend(void* arg, unsigned int r_type,
uint64_t) const
{
gold_assert(r_type == elfcpp::R_X86_64_TLSDESC);
uintptr_t intarg = reinterpret_cast<uintptr_t>(arg);
gold_assert(intarg < this->tlsdesc_reloc_info_.size());
const Tlsdesc_info& ti(this->tlsdesc_reloc_info_[intarg]);
const Symbol_value<size>* psymval = ti.object->local_symbol(ti.r_sym);
gold_assert(psymval->is_tls_symbol());
// The value of a TLS symbol is the offset in the TLS segment.
return psymval->value(ti.object, 0);
}
// Return the value to use for the base of a DW_EH_PE_datarel offset
// in an FDE. Solaris and SVR4 use DW_EH_PE_datarel because their
// assembler can not write out the difference between two labels in
// different sections, so instead of using a pc-relative value they
// use an offset from the GOT.
template<int size>
uint64_t
Target_x86_64<size>::do_ehframe_datarel_base() const
{
gold_assert(this->global_offset_table_ != NULL);
Symbol* sym = this->global_offset_table_;
Sized_symbol<size>* ssym = static_cast<Sized_symbol<size>*>(sym);
return ssym->value();
}
// FNOFFSET in section SHNDX in OBJECT is the start of a function
// compiled with -fsplit-stack. The function calls non-split-stack
// code. We have to change the function so that it always ensures
// that it has enough stack space to run some random function.
static const unsigned char cmp_insn_32[] = { 0x64, 0x3b, 0x24, 0x25 };
static const unsigned char lea_r10_insn_32[] = { 0x44, 0x8d, 0x94, 0x24 };
static const unsigned char lea_r11_insn_32[] = { 0x44, 0x8d, 0x9c, 0x24 };
static const unsigned char cmp_insn_64[] = { 0x64, 0x48, 0x3b, 0x24, 0x25 };
static const unsigned char lea_r10_insn_64[] = { 0x4c, 0x8d, 0x94, 0x24 };
static const unsigned char lea_r11_insn_64[] = { 0x4c, 0x8d, 0x9c, 0x24 };
template<int size>
void
Target_x86_64<size>::do_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
{
const char* const cmp_insn = reinterpret_cast<const char*>
(size == 32 ? cmp_insn_32 : cmp_insn_64);
const char* const lea_r10_insn = reinterpret_cast<const char*>
(size == 32 ? lea_r10_insn_32 : lea_r10_insn_64);
const char* const lea_r11_insn = reinterpret_cast<const char*>
(size == 32 ? lea_r11_insn_32 : lea_r11_insn_64);
const size_t cmp_insn_len =
(size == 32 ? sizeof(cmp_insn_32) : sizeof(cmp_insn_64));
const size_t lea_r10_insn_len =
(size == 32 ? sizeof(lea_r10_insn_32) : sizeof(lea_r10_insn_64));
const size_t lea_r11_insn_len =
(size == 32 ? sizeof(lea_r11_insn_32) : sizeof(lea_r11_insn_64));
const size_t nop_len = (size == 32 ? 7 : 8);
// The function starts with a comparison of the stack pointer and a
// field in the TCB. This is followed by a jump.
// cmp %fs:NN,%rsp
if (this->match_view(view, view_size, fnoffset, cmp_insn, cmp_insn_len)
&& fnsize > nop_len + 1)
{
// We will call __morestack if the carry flag is set after this
// comparison. We turn the comparison into an stc instruction
// and some nops.
view[fnoffset] = '\xf9';
this->set_view_to_nop(view, view_size, fnoffset + 1, nop_len);
}
// lea NN(%rsp),%r10
// lea NN(%rsp),%r11
else if ((this->match_view(view, view_size, fnoffset,
lea_r10_insn, lea_r10_insn_len)
|| this->match_view(view, view_size, fnoffset,
lea_r11_insn, lea_r11_insn_len))
&& fnsize > 8)
{
// This is loading an offset from the stack pointer for a
// comparison. The offset is negative, so we decrease the
// offset by the amount of space we need for the stack. This
// means we will avoid calling __morestack if there happens to
// be plenty of space on the stack already.
unsigned char* pval = view + fnoffset + 4;
uint32_t val = elfcpp::Swap_unaligned<32, false>::readval(pval);
val -= parameters->options().split_stack_adjust_size();
elfcpp::Swap_unaligned<32, false>::writeval(pval, val);
}
else
{
if (!object->has_no_split_stack())
object->error(_("failed to match split-stack sequence at "
"section %u offset %0zx"),
shndx, static_cast<size_t>(fnoffset));
return;
}
// We have to change the function so that it calls
// __morestack_non_split instead of __morestack. The former will
// allocate additional stack space.
*from = "__morestack";
*to = "__morestack_non_split";
}
// The selector for x86_64 object files. Note this is never instantiated
// directly. It's only used in Target_selector_x86_64_nacl, below.
template<int size>
class Target_selector_x86_64 : public Target_selector_freebsd
{
public:
Target_selector_x86_64()
: Target_selector_freebsd(elfcpp::EM_X86_64, size, false,
(size == 64
? "elf64-x86-64" : "elf32-x86-64"),
(size == 64
? "elf64-x86-64-freebsd"
: "elf32-x86-64-freebsd"),
(size == 64 ? "elf_x86_64" : "elf32_x86_64"))
{ }
Target*
do_instantiate_target()
{ return new Target_x86_64<size>(); }
};
// NaCl variant. It uses different PLT contents.
template<int size>
class Output_data_plt_x86_64_nacl : public Output_data_plt_x86_64<size>
{
public:
Output_data_plt_x86_64_nacl(Layout* layout,
Output_data_got<64, false>* got,
Output_data_got_plt_x86_64* got_plt,
Output_data_space* got_irelative)
: Output_data_plt_x86_64<size>(layout, plt_entry_size,
got, got_plt, got_irelative)
{ }
Output_data_plt_x86_64_nacl(Layout* layout,
Output_data_got<64, false>* got,
Output_data_got_plt_x86_64* got_plt,
Output_data_space* got_irelative,
unsigned int plt_count)
: Output_data_plt_x86_64<size>(layout, plt_entry_size,
got, got_plt, got_irelative,
plt_count)
{ }
protected:
virtual unsigned int
do_get_plt_entry_size() const
{ return plt_entry_size; }
virtual void
do_add_eh_frame(Layout* layout)
{
layout->add_eh_frame_for_plt(this,
this->plt_eh_frame_cie,
this->plt_eh_frame_cie_size,
plt_eh_frame_fde,
plt_eh_frame_fde_size);
}
virtual void
do_fill_first_plt_entry(unsigned char* pov,
typename elfcpp::Elf_types<size>::Elf_Addr got_addr,
typename elfcpp::Elf_types<size>::Elf_Addr plt_addr);
virtual unsigned int
do_fill_plt_entry(unsigned char* pov,
typename elfcpp::Elf_types<size>::Elf_Addr got_address,
typename elfcpp::Elf_types<size>::Elf_Addr plt_address,
unsigned int got_offset,
unsigned int plt_offset,
unsigned int plt_index);
virtual void
do_fill_tlsdesc_entry(unsigned char* pov,
typename elfcpp::Elf_types<size>::Elf_Addr got_address,
typename elfcpp::Elf_types<size>::Elf_Addr plt_address,
typename elfcpp::Elf_types<size>::Elf_Addr got_base,
unsigned int tlsdesc_got_offset,
unsigned int plt_offset);
private:
// The size of an entry in the PLT.
static const int plt_entry_size = 64;
// The first entry in the PLT.
static const unsigned char first_plt_entry[plt_entry_size];
// Other entries in the PLT for an executable.
static const unsigned char plt_entry[plt_entry_size];
// The reserved TLSDESC entry in the PLT for an executable.
static const unsigned char tlsdesc_plt_entry[plt_entry_size];
// The .eh_frame unwind information for the PLT.
static const int plt_eh_frame_fde_size = 32;
static const unsigned char plt_eh_frame_fde[plt_eh_frame_fde_size];
};
template<int size>
class Target_x86_64_nacl : public Target_x86_64<size>
{
public:
Target_x86_64_nacl()
: Target_x86_64<size>(&x86_64_nacl_info)
{ }
virtual Output_data_plt_x86_64<size>*
do_make_data_plt(Layout* layout,
Output_data_got<64, false>* got,
Output_data_got_plt_x86_64* got_plt,
Output_data_space* got_irelative)
{
return new Output_data_plt_x86_64_nacl<size>(layout, got, got_plt,
got_irelative);
}
virtual Output_data_plt_x86_64<size>*
do_make_data_plt(Layout* layout,
Output_data_got<64, false>* got,
Output_data_got_plt_x86_64* got_plt,
Output_data_space* got_irelative,
unsigned int plt_count)
{
return new Output_data_plt_x86_64_nacl<size>(layout, got, got_plt,
got_irelative,
plt_count);
}
virtual std::string
do_code_fill(section_size_type length) const;
private:
static const Target::Target_info x86_64_nacl_info;
};
template<>
const Target::Target_info Target_x86_64_nacl<64>::x86_64_nacl_info =
{
64, // size
false, // is_big_endian
elfcpp::EM_X86_64, // machine_code
false, // has_make_symbol
false, // has_resolve
true, // has_code_fill
true, // is_default_stack_executable
true, // can_icf_inline_merge_sections
'\0', // wrap_char
"/lib64/ld-nacl-x86-64.so.1", // dynamic_linker
0x20000, // default_text_segment_address
0x10000, // abi_pagesize (overridable by -z max-page-size)
0x10000, // common_pagesize (overridable by -z common-page-size)
true, // isolate_execinstr
0x10000000, // rosegment_gap
elfcpp::SHN_UNDEF, // small_common_shndx
elfcpp::SHN_X86_64_LCOMMON, // large_common_shndx
0, // small_common_section_flags
elfcpp::SHF_X86_64_LARGE, // large_common_section_flags
NULL, // attributes_section
NULL, // attributes_vendor
"_start" // entry_symbol_name
};
template<>
const Target::Target_info Target_x86_64_nacl<32>::x86_64_nacl_info =
{
32, // size
false, // is_big_endian
elfcpp::EM_X86_64, // machine_code
false, // has_make_symbol
false, // has_resolve
true, // has_code_fill
true, // is_default_stack_executable
true, // can_icf_inline_merge_sections
'\0', // wrap_char
"/lib/ld-nacl-x86-64.so.1", // dynamic_linker
0x20000, // default_text_segment_address
0x10000, // abi_pagesize (overridable by -z max-page-size)
0x10000, // common_pagesize (overridable by -z common-page-size)
true, // isolate_execinstr
0x10000000, // rosegment_gap
elfcpp::SHN_UNDEF, // small_common_shndx
elfcpp::SHN_X86_64_LCOMMON, // large_common_shndx
0, // small_common_section_flags
elfcpp::SHF_X86_64_LARGE, // large_common_section_flags
NULL, // attributes_section
NULL, // attributes_vendor
"_start" // entry_symbol_name
};
#define NACLMASK 0xe0 // 32-byte alignment mask.
// The first entry in the PLT.
template<int size>
const unsigned char
Output_data_plt_x86_64_nacl<size>::first_plt_entry[plt_entry_size] =
{
0xff, 0x35, // pushq contents of memory address
0, 0, 0, 0, // replaced with address of .got + 8
0x4c, 0x8b, 0x1d, // mov GOT+16(%rip), %r11
0, 0, 0, 0, // replaced with address of .got + 16
0x41, 0x83, 0xe3, NACLMASK, // and $-32, %r11d
0x4d, 0x01, 0xfb, // add %r15, %r11
0x41, 0xff, 0xe3, // jmpq *%r11
// 9-byte nop sequence to pad out to the next 32-byte boundary.
0x66, 0x0f, 0x1f, 0x84, 0, 0, 0, 0, 0, // nopw 0x0(%rax,%rax,1)
// 32 bytes of nop to pad out to the standard size
0x66, 0x66, 0x66, 0x66, 0x66, 0x66, // excess data32 prefixes
0x2e, 0x0f, 0x1f, 0x84, 0, 0, 0, 0, 0, // nopw %cs:0x0(%rax,%rax,1)
0x66, 0x66, 0x66, 0x66, 0x66, 0x66, // excess data32 prefixes
0x2e, 0x0f, 0x1f, 0x84, 0, 0, 0, 0, 0, // nopw %cs:0x0(%rax,%rax,1)
0x66, // excess data32 prefix
0x90 // nop
};
template<int size>
void
Output_data_plt_x86_64_nacl<size>::do_fill_first_plt_entry(
unsigned char* pov,
typename elfcpp::Elf_types<size>::Elf_Addr got_address,
typename elfcpp::Elf_types<size>::Elf_Addr plt_address)
{
memcpy(pov, first_plt_entry, plt_entry_size);
elfcpp::Swap_unaligned<32, false>::writeval(pov + 2,
(got_address + 8
- (plt_address + 2 + 4)));
elfcpp::Swap_unaligned<32, false>::writeval(pov + 9,
(got_address + 16
- (plt_address + 9 + 4)));
}
// Subsequent entries in the PLT.
template<int size>
const unsigned char
Output_data_plt_x86_64_nacl<size>::plt_entry[plt_entry_size] =
{
0x4c, 0x8b, 0x1d, // mov name@GOTPCREL(%rip),%r11
0, 0, 0, 0, // replaced with address of symbol in .got
0x41, 0x83, 0xe3, NACLMASK, // and $-32, %r11d
0x4d, 0x01, 0xfb, // add %r15, %r11
0x41, 0xff, 0xe3, // jmpq *%r11
// 15-byte nop sequence to pad out to the next 32-byte boundary.
0x66, 0x66, 0x66, 0x66, 0x66, 0x66, // excess data32 prefixes
0x2e, 0x0f, 0x1f, 0x84, 0, 0, 0, 0, 0, // nopw %cs:0x0(%rax,%rax,1)
// Lazy GOT entries point here (32-byte aligned).
0x68, // pushq immediate
0, 0, 0, 0, // replaced with index into relocation table
0xe9, // jmp relative
0, 0, 0, 0, // replaced with offset to start of .plt0
// 22 bytes of nop to pad out to the standard size.
0x66, 0x66, 0x66, 0x66, 0x66, 0x66, // excess data32 prefixes
0x2e, 0x0f, 0x1f, 0x84, 0, 0, 0, 0, 0, // nopw %cs:0x0(%rax,%rax,1)
0x0f, 0x1f, 0x80, 0, 0, 0, 0, // nopl 0x0(%rax)
};
template<int size>
unsigned int
Output_data_plt_x86_64_nacl<size>::do_fill_plt_entry(
unsigned char* pov,
typename elfcpp::Elf_types<size>::Elf_Addr got_address,
typename elfcpp::Elf_types<size>::Elf_Addr plt_address,
unsigned int got_offset,
unsigned int plt_offset,
unsigned int plt_index)
{
memcpy(pov, plt_entry, plt_entry_size);
elfcpp::Swap_unaligned<32, false>::writeval(pov + 3,
(got_address + got_offset
- (plt_address + plt_offset
+ 3 + 4)));
elfcpp::Swap_unaligned<32, false>::writeval(pov + 33, plt_index);
elfcpp::Swap_unaligned<32, false>::writeval(pov + 38,
- (plt_offset + 38 + 4));
return 32;
}
// The reserved TLSDESC entry in the PLT.
template<int size>
const unsigned char
Output_data_plt_x86_64_nacl<size>::tlsdesc_plt_entry[plt_entry_size] =
{
0xff, 0x35, // pushq x(%rip)
0, 0, 0, 0, // replaced with address of linkmap GOT entry (at PLTGOT + 8)
0x4c, 0x8b, 0x1d, // mov y(%rip),%r11
0, 0, 0, 0, // replaced with offset of reserved TLSDESC_GOT entry
0x41, 0x83, 0xe3, NACLMASK, // and $-32, %r11d
0x4d, 0x01, 0xfb, // add %r15, %r11
0x41, 0xff, 0xe3, // jmpq *%r11
// 41 bytes of nop to pad out to the standard size.
0x66, 0x66, 0x66, 0x66, 0x66, 0x66, // excess data32 prefixes
0x2e, 0x0f, 0x1f, 0x84, 0, 0, 0, 0, 0, // nopw %cs:0x0(%rax,%rax,1)
0x66, 0x66, 0x66, 0x66, 0x66, 0x66, // excess data32 prefixes
0x2e, 0x0f, 0x1f, 0x84, 0, 0, 0, 0, 0, // nopw %cs:0x0(%rax,%rax,1)
0x66, 0x66, // excess data32 prefixes
0x2e, 0x0f, 0x1f, 0x84, 0, 0, 0, 0, 0, // nopw %cs:0x0(%rax,%rax,1)
};
template<int size>
void
Output_data_plt_x86_64_nacl<size>::do_fill_tlsdesc_entry(
unsigned char* pov,
typename elfcpp::Elf_types<size>::Elf_Addr got_address,
typename elfcpp::Elf_types<size>::Elf_Addr plt_address,
typename elfcpp::Elf_types<size>::Elf_Addr got_base,
unsigned int tlsdesc_got_offset,
unsigned int plt_offset)
{
memcpy(pov, tlsdesc_plt_entry, plt_entry_size);
elfcpp::Swap_unaligned<32, false>::writeval(pov + 2,
(got_address + 8
- (plt_address + plt_offset
+ 2 + 4)));
elfcpp::Swap_unaligned<32, false>::writeval(pov + 9,
(got_base
+ tlsdesc_got_offset
- (plt_address + plt_offset
+ 9 + 4)));
}
// The .eh_frame unwind information for the PLT.
template<int size>
const unsigned char
Output_data_plt_x86_64_nacl<size>::plt_eh_frame_fde[plt_eh_frame_fde_size] =
{
0, 0, 0, 0, // Replaced with offset to .plt.
0, 0, 0, 0, // Replaced with size of .plt.
0, // Augmentation size.
elfcpp::DW_CFA_def_cfa_offset, 16, // DW_CFA_def_cfa_offset: 16.
elfcpp::DW_CFA_advance_loc + 6, // Advance 6 to __PLT__ + 6.
elfcpp::DW_CFA_def_cfa_offset, 24, // DW_CFA_def_cfa_offset: 24.
elfcpp::DW_CFA_advance_loc + 58, // Advance 58 to __PLT__ + 64.
elfcpp::DW_CFA_def_cfa_expression, // DW_CFA_def_cfa_expression.
13, // Block length.
elfcpp::DW_OP_breg7, 8, // Push %rsp + 8.
elfcpp::DW_OP_breg16, 0, // Push %rip.
elfcpp::DW_OP_const1u, 63, // Push 0x3f.
elfcpp::DW_OP_and, // & (%rip & 0x3f).
elfcpp::DW_OP_const1u, 37, // Push 0x25.
elfcpp::DW_OP_ge, // >= ((%rip & 0x3f) >= 0x25)
elfcpp::DW_OP_lit3, // Push 3.
elfcpp::DW_OP_shl, // << (((%rip & 0x3f) >= 0x25) << 3)
elfcpp::DW_OP_plus, // + ((((%rip&0x3f)>=0x25)<<3)+%rsp+8
elfcpp::DW_CFA_nop, // Align to 32 bytes.
elfcpp::DW_CFA_nop
};
// Return a string used to fill a code section with nops.
// For NaCl, long NOPs are only valid if they do not cross
// bundle alignment boundaries, so keep it simple with one-byte NOPs.
template<int size>
std::string
Target_x86_64_nacl<size>::do_code_fill(section_size_type length) const
{
return std::string(length, static_cast<char>(0x90));
}
// The selector for x86_64-nacl object files.
template<int size>
class Target_selector_x86_64_nacl
: public Target_selector_nacl<Target_selector_x86_64<size>,
Target_x86_64_nacl<size> >
{
public:
Target_selector_x86_64_nacl()
: Target_selector_nacl<Target_selector_x86_64<size>,
Target_x86_64_nacl<size> >("x86-64",
size == 64
? "elf64-x86-64-nacl"
: "elf32-x86-64-nacl",
size == 64
? "elf_x86_64_nacl"
: "elf32_x86_64_nacl")
{ }
};
Target_selector_x86_64_nacl<64> target_selector_x86_64;
Target_selector_x86_64_nacl<32> target_selector_x32;
} // End anonymous namespace.
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