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a82bef932e
binutils-gdb/gold/x86_64.cc
Sriraman Tallam a82bef932e With -pie and x86, the linker complains if it sees a PC-relative relocation 
to access a global as it expects a GOTPCREL relocation.  This is really not
necessary as the linker could use a copy relocation to get around it.  This
patch enables copy relocations with pie.

Context:
This is useful because currently the GCC compiler with option -fpie makes
every extern global access go through the GOT. That is because the compiler
cannot tell if a global will end up being defined in the executable or not
and is conservative. This ends up hurting performance when the binary is linked
as mostly static where most of the globals do end up being defined in the
executable.  By allowing copy relocs with fPIE, the compiler need not generate
a GOTPCREL(GOT access) for any global access.  It can safely assume that all
globals will be defined in the executable and generate a PC-relative access
instead.  Gold can then create a copy reloc for only the undefined globals.

	gold/
	* symtab.h (may_need_copy_reloc): Remove check for position independent
	code.
	* x86_64.cc (Target_x86_64<size>::Scan::global): Add check for no
	position independence before pc absolute may_need_copy_reloc call.
	Add check for executable output befor pc relative may_need_copy_reloc
	call.
	* i386.cc: Ditto.
	* arm.cc: Ditto.
	* sparc.cc: Ditto.
	* tilegx.cc: Ditto.
	* powerpc.cc: Add check for no position independence before
	may_need_copy_reloc calls.
	* testsuite/pie_copyrelocs_test.cc: New file.
	* testsuite/pie_copyrelocs_shared_test.cc: New file.
	* Makefile.am (pie_copyrelocs_test): New test.
	* Makefile.in: Regenerate.
2014-05-13 10:55:11 -07:00

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// x86_64.cc -- x86_64 target support for gold.
// Copyright (C) 2006-2014 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)
{
memcpy(pov, plt_entry, plt_entry_size);
elfcpp::Swap_unaligned<32, false>::writeval(pov + 2,
(got_address + got_offset
- (plt_address + plt_offset
+ 6)));
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);
}
}
}
// For GOTPLT64, we also need a PLT entry (but only if the
// symbol is not fully resolved).
if (r_type == elfcpp::R_X86_64_GOTPLT64
&& !gsym->final_value_is_known())
target->make_plt_entry(symtab, layout, gsym);
}
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
{
const bool is_final = gsym->final_value_is_known();
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;
unsigned 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;
got_address = target->got_section(NULL, NULL)->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:
// The ABI doc says "Like GOT64, but indicates a PLT entry is needed."
// Since we always add a PLT entry, this is equivalent.
case elfcpp::R_X86_64_GOTPLT64:
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 (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;
view[-2] = 0xc7;
view[-1] = 0xc0 | reg;
}
else if (reg == 4)
{
// Special handling for %rsp.
if (op1 == 0x4c)
view[-3] = 0x49;
view[-2] = 0x81;
view[-1] = 0xc0 | reg;
}
else
{
// addq
if (op1 == 0x4c)
view[-3] = 0x4d;
view[-2] = 0x8d;
view[-1] = 0x80 | reg | (reg << 3);
}
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.
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
{
// 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, "\x64\x48\x3b\x24\x25", 5)
&& fnsize > 9)
{
// 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, 8);
}
// lea NN(%rsp),%r10
// lea NN(%rsp),%r11
else if ((this->match_view(view, view_size, fnoffset,
"\x4c\x8d\x94\x24", 4)
|| this->match_view(view, view_size, fnoffset,
"\x4c\x8d\x9c\x24", 4))
&& 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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