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old-cross-binutils/gold/i386.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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// i386.cc -- i386 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 "i386.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"
namespace
{
using namespace gold;
// A class to handle the .got.plt section.
class Output_data_got_plt_i386 : public Output_section_data_build
{
public:
Output_data_got_plt_i386(Layout* layout)
: Output_section_data_build(4),
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.
class Output_data_plt_i386 : public Output_section_data
{
public:
typedef Output_data_reloc<elfcpp::SHT_REL, true, 32, false> Reloc_section;
Output_data_plt_i386(Layout*, uint64_t addralign,
Output_data_got_plt_i386*, Output_data_space*);
// 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*, Layout*,
Sized_relobj_file<32, false>* relobj,
unsigned int local_sym_index);
// Return the .rel.plt section data.
Reloc_section*
rel_plt() const
{ return this->rel_; }
// Return where the TLS_DESC relocations should go.
Reloc_section*
rel_tls_desc(Layout*);
// Return where the IRELATIVE relocations should go.
Reloc_section*
rel_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(); }
// 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 the first PLT entry, given the pointer to the PLT section data
// and the runtime address of the GOT.
void
fill_first_plt_entry(unsigned char* pov,
elfcpp::Elf_types<32>::Elf_Addr got_address)
{ this->do_fill_first_plt_entry(pov, got_address); }
// Fill a normal PLT entry, given the pointer to the entry's data in the
// section, the runtime address of the GOT, the offset into the GOT of
// the corresponding slot, the offset into the relocation section of the
// corresponding reloc, and the offset of this entry within the whole
// PLT. Return the offset from this PLT entry's runtime address that
// should be used to compute the initial value of the GOT slot.
unsigned int
fill_plt_entry(unsigned char* pov,
elfcpp::Elf_types<32>::Elf_Addr got_address,
unsigned int got_offset,
unsigned int plt_offset,
unsigned int plt_rel_offset)
{
return this->do_fill_plt_entry(pov, got_address, got_offset,
plt_offset, plt_rel_offset);
}
virtual unsigned int
do_get_plt_entry_size() const = 0;
virtual void
do_fill_first_plt_entry(unsigned char* pov,
elfcpp::Elf_types<32>::Elf_Addr got_address) = 0;
virtual unsigned int
do_fill_plt_entry(unsigned char* pov,
elfcpp::Elf_types<32>::Elf_Addr got_address,
unsigned int got_offset,
unsigned int plt_offset,
unsigned int plt_rel_offset) = 0;
virtual void
do_add_eh_frame(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 .eh_frame unwind information for the PLT.
// The CIE is common across variants of the PLT format.
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()
{
this->set_data_size((this->count_ + this->irelative_count_ + 1)
* this->get_plt_entry_size());
}
// Write out the PLT data.
void
do_write(Output_file*);
// We keep a list of global STT_GNU_IFUNC symbols, each with its
// offset in the GOT.
struct Global_ifunc
{
Symbol* sym;
unsigned int got_offset;
};
// We keep a list of local STT_GNU_IFUNC symbols, each with its
// offset in the GOT.
struct Local_ifunc
{
Sized_relobj_file<32, false>* object;
unsigned int local_sym_index;
unsigned int got_offset;
};
// The reloc section.
Reloc_section* rel_;
// The TLS_DESC relocations, if necessary. These must follow the
// regular PLT relocs.
Reloc_section* tls_desc_rel_;
// The IRELATIVE relocations, if necessary. These must follow the
// regular relocatoins and the TLS_DESC relocations.
Reloc_section* irelative_rel_;
// The .got.plt section.
Output_data_got_plt_i386* 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_386_IRELATIVE relocs. These follow
// the regular PLT entries.
unsigned int irelative_count_;
// Global STT_GNU_IFUNC symbols.
std::vector<Global_ifunc> global_ifuncs_;
// Local STT_GNU_IFUNC symbols.
std::vector<Local_ifunc> local_ifuncs_;
};
// This is an abstract class for the standard PLT layout.
// The derived classes below handle the actual PLT contents
// for the executable (non-PIC) and shared-library (PIC) cases.
// The unwind information is uniform across those two, so it's here.
class Output_data_plt_i386_standard : public Output_data_plt_i386
{
public:
Output_data_plt_i386_standard(Layout* layout,
Output_data_got_plt_i386* got_plt,
Output_data_space* got_irelative)
: Output_data_plt_i386(layout, plt_entry_size, got_plt, got_irelative)
{ }
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, plt_eh_frame_cie, plt_eh_frame_cie_size,
plt_eh_frame_fde, plt_eh_frame_fde_size);
}
// The size of an entry in the PLT.
static const int plt_entry_size = 16;
// 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];
};
// Actually fill the PLT contents for an executable (non-PIC).
class Output_data_plt_i386_exec : public Output_data_plt_i386_standard
{
public:
Output_data_plt_i386_exec(Layout* layout,
Output_data_got_plt_i386* got_plt,
Output_data_space* got_irelative)
: Output_data_plt_i386_standard(layout, got_plt, got_irelative)
{ }
protected:
virtual void
do_fill_first_plt_entry(unsigned char* pov,
elfcpp::Elf_types<32>::Elf_Addr got_address);
virtual unsigned int
do_fill_plt_entry(unsigned char* pov,
elfcpp::Elf_types<32>::Elf_Addr got_address,
unsigned int got_offset,
unsigned int plt_offset,
unsigned int plt_rel_offset);
private:
// The first entry in the PLT for an executable.
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];
};
// Actually fill the PLT contents for a shared library (PIC).
class Output_data_plt_i386_dyn : public Output_data_plt_i386_standard
{
public:
Output_data_plt_i386_dyn(Layout* layout,
Output_data_got_plt_i386* got_plt,
Output_data_space* got_irelative)
: Output_data_plt_i386_standard(layout, got_plt, got_irelative)
{ }
protected:
virtual void
do_fill_first_plt_entry(unsigned char* pov, elfcpp::Elf_types<32>::Elf_Addr);
virtual unsigned int
do_fill_plt_entry(unsigned char* pov,
elfcpp::Elf_types<32>::Elf_Addr,
unsigned int got_offset,
unsigned int plt_offset,
unsigned int plt_rel_offset);
private:
// The first entry in the PLT for a shared object.
static const unsigned char first_plt_entry[plt_entry_size];
// Other entries in the PLT for a shared object.
static const unsigned char plt_entry[plt_entry_size];
};
// The i386 target class.
// TLS info comes from
// http://people.redhat.com/drepper/tls.pdf
// http://www.lsd.ic.unicamp.br/~oliva/writeups/TLS/RFC-TLSDESC-x86.txt
class Target_i386 : public Sized_target<32, false>
{
public:
typedef Output_data_reloc<elfcpp::SHT_REL, true, 32, false> Reloc_section;
Target_i386(const Target::Target_info* info = &i386_info)
: Sized_target<32, false>(info),
got_(NULL), plt_(NULL), got_plt_(NULL), got_irelative_(NULL),
got_tlsdesc_(NULL), global_offset_table_(NULL), rel_dyn_(NULL),
rel_irelative_(NULL), copy_relocs_(elfcpp::R_386_COPY),
got_mod_index_offset_(-1U), tls_base_symbol_defined_(false)
{ }
// Process the relocations to determine unreferenced sections for
// garbage collection.
void
gc_process_relocs(Symbol_table* symtab,
Layout* layout,
Sized_relobj_file<32, 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<32, 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<32, 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,
elfcpp::Elf_types<32>::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<32, 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<32, false>*,
unsigned int sh_type,
const unsigned char* prelocs,
size_t reloc_count,
Output_section* output_section,
elfcpp::Elf_types<32>::Elf_Off offset_in_output_section,
const Relocatable_relocs*,
unsigned char* view,
elfcpp::Elf_types<32>::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 whether a symbol name implies a local label. The UnixWare
// 2.1 cc generates temporary symbols that start with .X, so we
// recognize them here. FIXME: do other SVR4 compilers also use .X?.
// If so, we should move the .X recognition into
// Target::do_is_local_label_name.
bool
do_is_local_label_name(const char* name) const
{
if (name[0] == '.' && name[1] == 'X')
return true;
return Target::do_is_local_label_name(name);
}
// Return the PLT address to use for a global symbol.
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); }
// We can tell whether we take the address of a function.
inline bool
do_can_check_for_function_pointers() const
{ return true; }
// Return the base for a DW_EH_PE_datarel encoding.
uint64_t
do_ehframe_datarel_base() const;
// Return whether SYM is call to a non-split function.
bool
do_is_call_to_non_split(const Symbol* sym, unsigned int) 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() / 4;
}
// 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;
protected:
// Instantiate the plt_ member.
// This chooses the right PLT flavor for an executable or a shared object.
Output_data_plt_i386*
make_data_plt(Layout* layout,
Output_data_got_plt_i386* got_plt,
Output_data_space* got_irelative,
bool dyn)
{ return this->do_make_data_plt(layout, got_plt, got_irelative, dyn); }
virtual Output_data_plt_i386*
do_make_data_plt(Layout* layout,
Output_data_got_plt_i386* got_plt,
Output_data_space* got_irelative,
bool dyn)
{
if (dyn)
return new Output_data_plt_i386_dyn(layout, got_plt, got_irelative);
else
return new Output_data_plt_i386_exec(layout, got_plt, got_irelative);
}
private:
// The class which scans relocations.
struct Scan
{
static inline int
get_reference_flags(unsigned int r_type);
inline void
local(Symbol_table* symtab, Layout* layout, Target_i386* target,
Sized_relobj_file<32, false>* object,
unsigned int data_shndx,
Output_section* output_section,
const elfcpp::Rel<32, false>& reloc, unsigned int r_type,
const elfcpp::Sym<32, false>& lsym,
bool is_discarded);
inline void
global(Symbol_table* symtab, Layout* layout, Target_i386* target,
Sized_relobj_file<32, false>* object,
unsigned int data_shndx,
Output_section* output_section,
const elfcpp::Rel<32, false>& reloc, unsigned int r_type,
Symbol* gsym);
inline bool
local_reloc_may_be_function_pointer(Symbol_table* symtab, Layout* layout,
Target_i386* target,
Sized_relobj_file<32, false>* object,
unsigned int data_shndx,
Output_section* output_section,
const elfcpp::Rel<32, false>& reloc,
unsigned int r_type,
const elfcpp::Sym<32, false>& lsym);
inline bool
global_reloc_may_be_function_pointer(Symbol_table* symtab, Layout* layout,
Target_i386* target,
Sized_relobj_file<32, false>* object,
unsigned int data_shndx,
Output_section* output_section,
const elfcpp::Rel<32, false>& reloc,
unsigned int r_type,
Symbol* gsym);
inline bool
possible_function_pointer_reloc(unsigned int r_type);
bool
reloc_needs_plt_for_ifunc(Sized_relobj_file<32, false>*,
unsigned int r_type);
static void
unsupported_reloc_local(Sized_relobj_file<32, false>*, unsigned int r_type);
static void
unsupported_reloc_global(Sized_relobj_file<32, false>*, unsigned int r_type,
Symbol*);
};
// The class which implements relocation.
class Relocate
{
public:
Relocate()
: skip_call_tls_get_addr_(false),
local_dynamic_type_(LOCAL_DYNAMIC_NONE)
{ }
~Relocate()
{
if (this->skip_call_tls_get_addr_)
{
// FIXME: This needs to specify the location somehow.
gold_error(_("missing expected TLS relocation"));
}
}
// Return whether the static relocation needs to be applied.
inline bool
should_apply_static_reloc(const Sized_symbol<32>* gsym,
unsigned int r_type,
bool is_32bit,
Output_section* output_section);
// Do a relocation. Return false if the caller should not issue
// any warnings about this relocation.
inline bool
relocate(const Relocate_info<32, false>*, Target_i386*, Output_section*,
size_t relnum, const elfcpp::Rel<32, false>&,
unsigned int r_type, const Sized_symbol<32>*,
const Symbol_value<32>*,
unsigned char*, elfcpp::Elf_types<32>::Elf_Addr,
section_size_type);
private:
// Do a TLS relocation.
inline void
relocate_tls(const Relocate_info<32, false>*, Target_i386* target,
size_t relnum, const elfcpp::Rel<32, false>&,
unsigned int r_type, const Sized_symbol<32>*,
const Symbol_value<32>*,
unsigned char*, elfcpp::Elf_types<32>::Elf_Addr,
section_size_type);
// Do a TLS General-Dynamic to Initial-Exec transition.
inline void
tls_gd_to_ie(const Relocate_info<32, false>*, size_t relnum,
Output_segment* tls_segment,
const elfcpp::Rel<32, false>&, unsigned int r_type,
elfcpp::Elf_types<32>::Elf_Addr value,
unsigned char* view,
section_size_type view_size);
// Do a TLS General-Dynamic to Local-Exec transition.
inline void
tls_gd_to_le(const Relocate_info<32, false>*, size_t relnum,
Output_segment* tls_segment,
const elfcpp::Rel<32, false>&, unsigned int r_type,
elfcpp::Elf_types<32>::Elf_Addr value,
unsigned char* view,
section_size_type view_size);
// Do a TLS_GOTDESC or TLS_DESC_CALL General-Dynamic to Initial-Exec
// transition.
inline void
tls_desc_gd_to_ie(const Relocate_info<32, false>*, size_t relnum,
Output_segment* tls_segment,
const elfcpp::Rel<32, false>&, unsigned int r_type,
elfcpp::Elf_types<32>::Elf_Addr value,
unsigned char* view,
section_size_type view_size);
// Do a TLS_GOTDESC or TLS_DESC_CALL General-Dynamic to Local-Exec
// transition.
inline void
tls_desc_gd_to_le(const Relocate_info<32, false>*, size_t relnum,
Output_segment* tls_segment,
const elfcpp::Rel<32, false>&, unsigned int r_type,
elfcpp::Elf_types<32>::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<32, false>*, size_t relnum,
Output_segment* tls_segment,
const elfcpp::Rel<32, false>&, unsigned int r_type,
elfcpp::Elf_types<32>::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<32, false>*, size_t relnum,
Output_segment* tls_segment,
const elfcpp::Rel<32, false>&, unsigned int r_type,
elfcpp::Elf_types<32>::Elf_Addr value,
unsigned char* view,
section_size_type view_size);
// We need to keep track of which type of local dynamic relocation
// we have seen, so that we can optimize R_386_TLS_LDO_32 correctly.
enum Local_dynamic_type
{
LOCAL_DYNAMIC_NONE,
LOCAL_DYNAMIC_SUN,
LOCAL_DYNAMIC_GNU
};
// 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_;
// The type of local dynamic relocation we have seen in the section
// being relocated, if any.
Local_dynamic_type local_dynamic_type_;
};
// 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<32, false>*
got_section(Symbol_table*, Layout*);
// Get the GOT PLT section.
Output_data_got_plt_i386*
got_plt_section() const
{
gold_assert(this->got_plt_ != NULL);
return this->got_plt_;
}
// Get the GOT section for TLSDESC entries.
Output_data_got<32, 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<32, 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 a GOT entry for the TLS module index.
unsigned int
got_mod_index_entry(Symbol_table* symtab, Layout* layout,
Sized_relobj_file<32, false>* object);
// Get the PLT section.
Output_data_plt_i386*
plt_section() const
{
gold_assert(this->plt_ != NULL);
return this->plt_;
}
// Get the dynamic reloc section, creating it if necessary.
Reloc_section*
rel_dyn_section(Layout*);
// Get the section to use for TLS_DESC relocations.
Reloc_section*
rel_tls_desc_section(Layout*) const;
// Get the section to use for IRELATIVE relocations.
Reloc_section*
rel_irelative_section(Layout*);
// Add a potential copy relocation.
void
copy_reloc(Symbol_table* symtab, Layout* layout,
Sized_relobj_file<32, false>* object,
unsigned int shndx, Output_section* output_section,
Symbol* sym, const elfcpp::Rel<32, false>& reloc)
{
this->copy_relocs_.copy_reloc(symtab, layout,
symtab->get_sized_symbol<32>(sym),
object, shndx, output_section, reloc,
this->rel_dyn_section(layout));
}
// Information about this specific target which we pass to the
// general Target structure.
static const Target::Target_info i386_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_NOFFSET = 1, // GOT entry for negative TLS offset
GOT_TYPE_TLS_OFFSET = 2, // GOT entry for positive TLS offset
GOT_TYPE_TLS_PAIR = 3, // GOT entry for TLS module/offset pair
GOT_TYPE_TLS_DESC = 4 // GOT entry for TLS_DESC pair
};
// The GOT section.
Output_data_got<32, false>* got_;
// The PLT section.
Output_data_plt_i386* plt_;
// The GOT PLT section.
Output_data_got_plt_i386* got_plt_;
// The GOT section for IRELATIVE relocations.
Output_data_space* got_irelative_;
// The GOT section for TLSDESC relocations.
Output_data_got<32, false>* got_tlsdesc_;
// The _GLOBAL_OFFSET_TABLE_ symbol.
Symbol* global_offset_table_;
// The dynamic reloc section.
Reloc_section* rel_dyn_;
// The section to use for IRELATIVE relocs.
Reloc_section* rel_irelative_;
// Relocs saved to avoid a COPY reloc.
Copy_relocs<elfcpp::SHT_REL, 32, false> copy_relocs_;
// Offset of the GOT entry for the TLS module index.
unsigned int got_mod_index_offset_;
// True if the _TLS_MODULE_BASE_ symbol has been defined.
bool tls_base_symbol_defined_;
};
const Target::Target_info Target_i386::i386_info =
{
32, // size
false, // is_big_endian
elfcpp::EM_386, // 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
"/usr/lib/libc.so.1", // dynamic_linker
0x08048000, // 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_UNDEF, // large_common_shndx
0, // small_common_section_flags
0, // large_common_section_flags
NULL, // attributes_section
NULL, // attributes_vendor
"_start" // entry_symbol_name
};
// Get the GOT section, creating it if necessary.
Output_data_got<32, false>*
Target_i386::got_section(Symbol_table* symtab, Layout* layout)
{
if (this->got_ == NULL)
{
gold_assert(symtab != NULL && layout != NULL);
this->got_ = new Output_data_got<32, false>();
// 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);
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_i386(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 * 4);
if (!is_got_plt_relro)
{
// Those bytes can go into the relro segment.
layout->increase_relro(3 * 4);
}
// 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 relocations.
this->got_irelative_ = new Output_data_space(4, "** 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 entries.
this->got_tlsdesc_ = new Output_data_got<32, 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.
Target_i386::Reloc_section*
Target_i386::rel_dyn_section(Layout* layout)
{
if (this->rel_dyn_ == NULL)
{
gold_assert(layout != NULL);
this->rel_dyn_ = new Reloc_section(parameters->options().combreloc());
layout->add_output_section_data(".rel.dyn", elfcpp::SHT_REL,
elfcpp::SHF_ALLOC, this->rel_dyn_,
ORDER_DYNAMIC_RELOCS, false);
}
return this->rel_dyn_;
}
// Get the section to use for IRELATIVE relocs, creating it if
// necessary. These go in .rel.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.
Target_i386::Reloc_section*
Target_i386::rel_irelative_section(Layout* layout)
{
if (this->rel_irelative_ == NULL)
{
// Make sure we have already create the dynamic reloc section.
this->rel_dyn_section(layout);
this->rel_irelative_ = new Reloc_section(false);
layout->add_output_section_data(".rel.dyn", elfcpp::SHT_REL,
elfcpp::SHF_ALLOC, this->rel_irelative_,
ORDER_DYNAMIC_RELOCS, false);
gold_assert(this->rel_dyn_->output_section()
== this->rel_irelative_->output_section());
}
return this->rel_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_i386::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_i386::got_section.
const off_t got_file_offset = this->offset();
gold_assert(this->data_size() >= 12);
unsigned char* const got_view = of->get_output_view(got_file_offset, 12);
Output_section* dynamic = this->layout_->dynamic_section();
uint32_t dynamic_addr = dynamic == NULL ? 0 : dynamic->address();
elfcpp::Swap<32, false>::writeval(got_view, dynamic_addr);
memset(got_view + 4, 0, 8);
of->write_output_view(got_file_offset, 12, got_view);
}
// Create the PLT section. The ordinary .got section is an argument,
// since we need to refer to the start. We also create our own .got
// section just for PLT entries.
Output_data_plt_i386::Output_data_plt_i386(Layout* layout,
uint64_t addralign,
Output_data_got_plt_i386* got_plt,
Output_data_space* got_irelative)
: Output_section_data(addralign),
tls_desc_rel_(NULL), irelative_rel_(NULL), got_plt_(got_plt),
got_irelative_(got_irelative), count_(0), irelative_count_(0),
global_ifuncs_(), local_ifuncs_()
{
this->rel_ = new Reloc_section(false);
layout->add_output_section_data(".rel.plt", elfcpp::SHT_REL,
elfcpp::SHF_ALLOC, this->rel_,
ORDER_DYNAMIC_PLT_RELOCS, false);
}
void
Output_data_plt_i386::do_adjust_output_section(Output_section* os)
{
// UnixWare sets the entsize of .plt to 4, and so does the old GNU
// linker, and so do we.
os->set_entsize(4);
}
// Add an entry to the PLT.
void
Output_data_plt_i386::add_entry(Symbol_table* symtab, Layout* layout,
Symbol* gsym)
{
gold_assert(!gsym->has_plt_offset());
// Every PLT entry needs a reloc.
if (gsym->type() == elfcpp::STT_GNU_IFUNC
&& gsym->can_use_relative_reloc(false))
{
gsym->set_plt_offset(this->irelative_count_ * this->get_plt_entry_size());
++this->irelative_count_;
section_offset_type got_offset =
this->got_irelative_->current_data_size();
this->got_irelative_->set_current_data_size(got_offset + 4);
Reloc_section* rel = this->rel_irelative(symtab, layout);
rel->add_symbolless_global_addend(gsym, elfcpp::R_386_IRELATIVE,
this->got_irelative_, got_offset);
struct Global_ifunc gi;
gi.sym = gsym;
gi.got_offset = got_offset;
this->global_ifuncs_.push_back(gi);
}
else
{
// When setting the PLT offset we skip the initial reserved PLT
// entry.
gsym->set_plt_offset((this->count_ + 1) * this->get_plt_entry_size());
++this->count_;
section_offset_type got_offset = this->got_plt_->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).
this->got_plt_->set_current_data_size(got_offset + 4);
gsym->set_needs_dynsym_entry();
this->rel_->add_global(gsym, elfcpp::R_386_JUMP_SLOT, this->got_plt_,
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.
unsigned int
Output_data_plt_i386::add_local_ifunc_entry(
Symbol_table* symtab,
Layout* layout,
Sized_relobj_file<32, 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 + 4);
// Every PLT entry needs a reloc.
Reloc_section* rel = this->rel_irelative(symtab, layout);
rel->add_symbolless_local_addend(relobj, local_sym_index,
elfcpp::R_386_IRELATIVE,
this->got_irelative_, got_offset);
struct Local_ifunc li;
li.object = relobj;
li.local_sym_index = local_sym_index;
li.got_offset = got_offset;
this->local_ifuncs_.push_back(li);
return plt_offset;
}
// Return where the TLS_DESC relocations should go, creating it if
// necessary. These follow the JUMP_SLOT relocations.
Output_data_plt_i386::Reloc_section*
Output_data_plt_i386::rel_tls_desc(Layout* layout)
{
if (this->tls_desc_rel_ == NULL)
{
this->tls_desc_rel_ = new Reloc_section(false);
layout->add_output_section_data(".rel.plt", elfcpp::SHT_REL,
elfcpp::SHF_ALLOC, this->tls_desc_rel_,
ORDER_DYNAMIC_PLT_RELOCS, false);
gold_assert(this->tls_desc_rel_->output_section()
== this->rel_->output_section());
}
return this->tls_desc_rel_;
}
// Return where the IRELATIVE relocations should go in the PLT. These
// follow the JUMP_SLOT and TLS_DESC relocations.
Output_data_plt_i386::Reloc_section*
Output_data_plt_i386::rel_irelative(Symbol_table* symtab, Layout* layout)
{
if (this->irelative_rel_ == NULL)
{
// Make sure we have a place for the TLS_DESC relocations, in
// case we see any later on.
this->rel_tls_desc(layout);
this->irelative_rel_ = new Reloc_section(false);
layout->add_output_section_data(".rel.plt", elfcpp::SHT_REL,
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 .rel.plt
// section to hold R_386_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("__rel_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("__rel_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.
uint64_t
Output_data_plt_i386::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.
uint64_t
Output_data_plt_i386::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));
}
// The first entry in the PLT for an executable.
const unsigned char Output_data_plt_i386_exec::first_plt_entry[plt_entry_size] =
{
0xff, 0x35, // pushl contents of memory address
0, 0, 0, 0, // replaced with address of .got + 4
0xff, 0x25, // jmp indirect
0, 0, 0, 0, // replaced with address of .got + 8
0, 0, 0, 0 // unused
};
void
Output_data_plt_i386_exec::do_fill_first_plt_entry(
unsigned char* pov,
elfcpp::Elf_types<32>::Elf_Addr got_address)
{
memcpy(pov, first_plt_entry, plt_entry_size);
elfcpp::Swap_unaligned<32, false>::writeval(pov + 2, got_address + 4);
elfcpp::Swap<32, false>::writeval(pov + 8, got_address + 8);
}
// The first entry in the PLT for a shared object.
const unsigned char Output_data_plt_i386_dyn::first_plt_entry[plt_entry_size] =
{
0xff, 0xb3, 4, 0, 0, 0, // pushl 4(%ebx)
0xff, 0xa3, 8, 0, 0, 0, // jmp *8(%ebx)
0, 0, 0, 0 // unused
};
void
Output_data_plt_i386_dyn::do_fill_first_plt_entry(
unsigned char* pov,
elfcpp::Elf_types<32>::Elf_Addr)
{
memcpy(pov, first_plt_entry, plt_entry_size);
}
// Subsequent entries in the PLT for an executable.
const unsigned char Output_data_plt_i386_exec::plt_entry[plt_entry_size] =
{
0xff, 0x25, // jmp indirect
0, 0, 0, 0, // replaced with address of symbol in .got
0x68, // pushl immediate
0, 0, 0, 0, // replaced with offset into relocation table
0xe9, // jmp relative
0, 0, 0, 0 // replaced with offset to start of .plt
};
unsigned int
Output_data_plt_i386_exec::do_fill_plt_entry(
unsigned char* pov,
elfcpp::Elf_types<32>::Elf_Addr got_address,
unsigned int got_offset,
unsigned int plt_offset,
unsigned int plt_rel_offset)
{
memcpy(pov, plt_entry, plt_entry_size);
elfcpp::Swap_unaligned<32, false>::writeval(pov + 2,
got_address + got_offset);
elfcpp::Swap_unaligned<32, false>::writeval(pov + 7, plt_rel_offset);
elfcpp::Swap<32, false>::writeval(pov + 12, - (plt_offset + 12 + 4));
return 6;
}
// Subsequent entries in the PLT for a shared object.
const unsigned char Output_data_plt_i386_dyn::plt_entry[plt_entry_size] =
{
0xff, 0xa3, // jmp *offset(%ebx)
0, 0, 0, 0, // replaced with offset of symbol in .got
0x68, // pushl immediate
0, 0, 0, 0, // replaced with offset into relocation table
0xe9, // jmp relative
0, 0, 0, 0 // replaced with offset to start of .plt
};
unsigned int
Output_data_plt_i386_dyn::do_fill_plt_entry(unsigned char* pov,
elfcpp::Elf_types<32>::Elf_Addr,
unsigned int got_offset,
unsigned int plt_offset,
unsigned int plt_rel_offset)
{
memcpy(pov, plt_entry, plt_entry_size);
elfcpp::Swap_unaligned<32, false>::writeval(pov + 2, got_offset);
elfcpp::Swap_unaligned<32, false>::writeval(pov + 7, plt_rel_offset);
elfcpp::Swap<32, false>::writeval(pov + 12, - (plt_offset + 12 + 4));
return 6;
}
// The .eh_frame unwind information for the PLT.
const unsigned char
Output_data_plt_i386::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.
0x7c, // Data alignment factor.
8, // Return address column.
1, // Augmentation size.
(elfcpp::DW_EH_PE_pcrel // FDE encoding.
| elfcpp::DW_EH_PE_sdata4),
elfcpp::DW_CFA_def_cfa, 4, 4, // DW_CFA_def_cfa: r4 (esp) ofs 4.
elfcpp::DW_CFA_offset + 8, 1, // DW_CFA_offset: r8 (eip) at cfa-4.
elfcpp::DW_CFA_nop, // Align to 16 bytes.
elfcpp::DW_CFA_nop
};
const unsigned char
Output_data_plt_i386_standard::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, 8, // DW_CFA_def_cfa_offset: 8.
elfcpp::DW_CFA_advance_loc + 6, // Advance 6 to __PLT__ + 6.
elfcpp::DW_CFA_def_cfa_offset, 12, // DW_CFA_def_cfa_offset: 12.
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_breg4, 4, // Push %esp + 4.
elfcpp::DW_OP_breg8, 0, // Push %eip.
elfcpp::DW_OP_lit15, // Push 0xf.
elfcpp::DW_OP_and, // & (%eip & 0xf).
elfcpp::DW_OP_lit11, // Push 0xb.
elfcpp::DW_OP_ge, // >= ((%eip & 0xf) >= 0xb)
elfcpp::DW_OP_lit2, // Push 2.
elfcpp::DW_OP_shl, // << (((%eip & 0xf) >= 0xb) << 2)
elfcpp::DW_OP_plus, // + ((((%eip&0xf)>=0xb)<<2)+%esp+4
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 all specified by the i386 ELF
// Processor Supplement.
void
Output_data_plt_i386::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;
elfcpp::Elf_types<32>::Elf_Addr plt_address = this->address();
elfcpp::Elf_types<32>::Elf_Addr got_address = this->got_plt_->address();
this->fill_first_plt_entry(pov, got_address);
pov += this->get_plt_entry_size();
// The first three entries in the GOT are reserved, and are written
// by Output_data_got_plt_i386::do_write.
unsigned char* got_pov = got_view + 12;
const int rel_size = elfcpp::Elf_sizes<32>::rel_size;
unsigned int plt_offset = this->get_plt_entry_size();
unsigned int plt_rel_offset = 0;
unsigned int got_offset = 12;
const unsigned int count = this->count_ + this->irelative_count_;
for (unsigned int i = 0;
i < count;
++i,
pov += this->get_plt_entry_size(),
got_pov += 4,
plt_offset += this->get_plt_entry_size(),
plt_rel_offset += rel_size,
got_offset += 4)
{
// Set and adjust the PLT entry itself.
unsigned int lazy_offset = this->fill_plt_entry(pov,
got_address,
got_offset,
plt_offset,
plt_rel_offset);
// Set the entry in the GOT.
elfcpp::Swap<32, false>::writeval(got_pov,
plt_address + plt_offset + lazy_offset);
}
// If any STT_GNU_IFUNC symbols have PLT entries, we need to change
// the GOT to point to the actual symbol value, rather than point to
// the PLT entry. That will let the dynamic linker call the right
// function when resolving IRELATIVE relocations.
unsigned char* got_irelative_view = got_view + this->got_plt_->data_size();
for (std::vector<Global_ifunc>::const_iterator p =
this->global_ifuncs_.begin();
p != this->global_ifuncs_.end();
++p)
{
const Sized_symbol<32>* ssym =
static_cast<const Sized_symbol<32>*>(p->sym);
elfcpp::Swap<32, false>::writeval(got_irelative_view + p->got_offset,
ssym->value());
}
for (std::vector<Local_ifunc>::const_iterator p =
this->local_ifuncs_.begin();
p != this->local_ifuncs_.end();
++p)
{
const Symbol_value<32>* psymval =
p->object->local_symbol(p->local_sym_index);
elfcpp::Swap<32, false>::writeval(got_irelative_view + p->got_offset,
psymval->value(p->object, 0));
}
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.
void
Target_i386::make_plt_section(Symbol_table* symtab, Layout* layout)
{
if (this->plt_ == NULL)
{
// Create the GOT sections first.
this->got_section(symtab, layout);
const bool dyn = parameters->options().output_is_position_independent();
this->plt_ = this->make_data_plt(layout,
this->got_plt_,
this->got_irelative_,
dyn);
// 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 .rel.plt point to .plt.
Output_section* rel_plt_os = this->plt_->rel_plt()->output_section();
rel_plt_os->set_info_section(this->plt_->output_section());
}
}
// Create a PLT entry for a global symbol.
void
Target_i386::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.
void
Target_i386::make_local_ifunc_plt_entry(Symbol_table* symtab, Layout* layout,
Sized_relobj_file<32, 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.
unsigned int
Target_i386::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.
unsigned int
Target_i386::first_plt_entry_offset() const
{
return this->plt_->first_plt_entry_offset();
}
// Return the size of each PLT entry.
unsigned int
Target_i386::plt_entry_size() const
{
return this->plt_->get_plt_entry_size();
}
// Get the section to use for TLS_DESC relocations.
Target_i386::Reloc_section*
Target_i386::rel_tls_desc_section(Layout* layout) const
{
return this->plt_section()->rel_tls_desc(layout);
}
// Define the _TLS_MODULE_BASE_ symbol in the TLS segment.
void
Target_i386::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 a GOT entry for the TLS module index.
unsigned int
Target_i386::got_mod_index_entry(Symbol_table* symtab, Layout* layout,
Sized_relobj_file<32, false>* object)
{
if (this->got_mod_index_offset_ == -1U)
{
gold_assert(symtab != NULL && layout != NULL && object != NULL);
Reloc_section* rel_dyn = this->rel_dyn_section(layout);
Output_data_got<32, false>* got = this->got_section(symtab, layout);
unsigned int got_offset = got->add_constant(0);
rel_dyn->add_local(object, 0, elfcpp::R_386_TLS_DTPMOD32, got,
got_offset);
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.
tls::Tls_optimization
Target_i386::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_386_TLS_GD:
case elfcpp::R_386_TLS_GOTDESC:
case elfcpp::R_386_TLS_DESC_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_386_TLS_LDM:
// 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_386_TLS_LDO_32:
// Another type of Local-Dynamic relocation.
return tls::TLSOPT_TO_LE;
case elfcpp::R_386_TLS_IE:
case elfcpp::R_386_TLS_GOTIE:
case elfcpp::R_386_TLS_IE_32:
// 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_386_TLS_LE:
case elfcpp::R_386_TLS_LE_32:
// 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.
int
Target_i386::Scan::get_reference_flags(unsigned int r_type)
{
switch (r_type)
{
case elfcpp::R_386_NONE:
case elfcpp::R_386_GNU_VTINHERIT:
case elfcpp::R_386_GNU_VTENTRY:
case elfcpp::R_386_GOTPC:
// No symbol reference.
return 0;
case elfcpp::R_386_32:
case elfcpp::R_386_16:
case elfcpp::R_386_8:
return Symbol::ABSOLUTE_REF;
case elfcpp::R_386_PC32:
case elfcpp::R_386_PC16:
case elfcpp::R_386_PC8:
case elfcpp::R_386_GOTOFF:
return Symbol::RELATIVE_REF;
case elfcpp::R_386_PLT32:
return Symbol::FUNCTION_CALL | Symbol::RELATIVE_REF;
case elfcpp::R_386_GOT32:
// Absolute in GOT.
return Symbol::ABSOLUTE_REF;
case elfcpp::R_386_TLS_GD: // Global-dynamic
case elfcpp::R_386_TLS_GOTDESC: // Global-dynamic (from ~oliva url)
case elfcpp::R_386_TLS_DESC_CALL:
case elfcpp::R_386_TLS_LDM: // Local-dynamic
case elfcpp::R_386_TLS_LDO_32: // Alternate local-dynamic
case elfcpp::R_386_TLS_IE: // Initial-exec
case elfcpp::R_386_TLS_IE_32:
case elfcpp::R_386_TLS_GOTIE:
case elfcpp::R_386_TLS_LE: // Local-exec
case elfcpp::R_386_TLS_LE_32:
return Symbol::TLS_REF;
case elfcpp::R_386_COPY:
case elfcpp::R_386_GLOB_DAT:
case elfcpp::R_386_JUMP_SLOT:
case elfcpp::R_386_RELATIVE:
case elfcpp::R_386_IRELATIVE:
case elfcpp::R_386_TLS_TPOFF:
case elfcpp::R_386_TLS_DTPMOD32:
case elfcpp::R_386_TLS_DTPOFF32:
case elfcpp::R_386_TLS_TPOFF32:
case elfcpp::R_386_TLS_DESC:
case elfcpp::R_386_32PLT:
case elfcpp::R_386_TLS_GD_32:
case elfcpp::R_386_TLS_GD_PUSH:
case elfcpp::R_386_TLS_GD_CALL:
case elfcpp::R_386_TLS_GD_POP:
case elfcpp::R_386_TLS_LDM_32:
case elfcpp::R_386_TLS_LDM_PUSH:
case elfcpp::R_386_TLS_LDM_CALL:
case elfcpp::R_386_TLS_LDM_POP:
case elfcpp::R_386_USED_BY_INTEL_200:
default:
// Not expected. We will give an error later.
return 0;
}
}
// Report an unsupported relocation against a local symbol.
void
Target_i386::Scan::unsupported_reloc_local(Sized_relobj_file<32, false>* object,
unsigned int r_type)
{
gold_error(_("%s: unsupported reloc %u against local symbol"),
object->name().c_str(), r_type);
}
// Return whether we need to make a PLT entry for a relocation of a
// given type against a STT_GNU_IFUNC symbol.
bool
Target_i386::Scan::reloc_needs_plt_for_ifunc(
Sized_relobj_file<32, 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.
inline void
Target_i386::Scan::local(Symbol_table* symtab,
Layout* layout,
Target_i386* target,
Sized_relobj_file<32, false>* object,
unsigned int data_shndx,
Output_section* output_section,
const elfcpp::Rel<32, false>& reloc,
unsigned int r_type,
const elfcpp::Sym<32, false>& lsym,
bool is_discarded)
{
if (is_discarded)
return;
// A local STT_GNU_IFUNC symbol may require a PLT entry.
if (lsym.get_st_type() == elfcpp::STT_GNU_IFUNC
&& this->reloc_needs_plt_for_ifunc(object, r_type))
{
unsigned int r_sym = elfcpp::elf_r_sym<32>(reloc.get_r_info());
target->make_local_ifunc_plt_entry(symtab, layout, object, r_sym);
}
switch (r_type)
{
case elfcpp::R_386_NONE:
case elfcpp::R_386_GNU_VTINHERIT:
case elfcpp::R_386_GNU_VTENTRY:
break;
case elfcpp::R_386_32:
// 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_386_RELATIVE relocation so the dynamic loader can
// relocate it easily.
if (parameters->options().output_is_position_independent())
{
Reloc_section* rel_dyn = target->rel_dyn_section(layout);
unsigned int r_sym = elfcpp::elf_r_sym<32>(reloc.get_r_info());
rel_dyn->add_local_relative(object, r_sym, elfcpp::R_386_RELATIVE,
output_section, data_shndx,
reloc.get_r_offset());
}
break;
case elfcpp::R_386_16:
case elfcpp::R_386_8:
// If building a shared library (or a position-independent
// executable), we need to create a dynamic relocation for
// this location. Because the addend needs to remain in the
// data section, we need to be careful not to apply this
// relocation statically.
if (parameters->options().output_is_position_independent())
{
Reloc_section* rel_dyn = target->rel_dyn_section(layout);
unsigned int r_sym = elfcpp::elf_r_sym<32>(reloc.get_r_info());
if (lsym.get_st_type() != elfcpp::STT_SECTION)
rel_dyn->add_local(object, r_sym, r_type, output_section,
data_shndx, reloc.get_r_offset());
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
rel_dyn->add_local_section(object, shndx,
r_type, output_section,
data_shndx, reloc.get_r_offset());
}
}
break;
case elfcpp::R_386_PC32:
case elfcpp::R_386_PC16:
case elfcpp::R_386_PC8:
break;
case elfcpp::R_386_PLT32:
// Since we know this is a local symbol, we can handle this as a
// PC32 reloc.
break;
case elfcpp::R_386_GOTOFF:
case elfcpp::R_386_GOTPC:
// We need a GOT section.
target->got_section(symtab, layout);
break;
case elfcpp::R_386_GOT32:
{
// The symbol requires a GOT entry.
Output_data_got<32, false>* got = target->got_section(symtab, layout);
unsigned int r_sym = elfcpp::elf_r_sym<32>(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 (lsym.get_st_type() == elfcpp::STT_GNU_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 RELATIVE relocation for this symbol's GOT entry.
if (parameters->options().output_is_position_independent())
{
Reloc_section* rel_dyn = target->rel_dyn_section(layout);
unsigned int got_offset =
object->local_got_offset(r_sym, GOT_TYPE_STANDARD);
rel_dyn->add_local_relative(object, r_sym,
elfcpp::R_386_RELATIVE,
got, got_offset);
}
}
}
break;
// These are relocations which should only be seen by the
// dynamic linker, and should never be seen here.
case elfcpp::R_386_COPY:
case elfcpp::R_386_GLOB_DAT:
case elfcpp::R_386_JUMP_SLOT:
case elfcpp::R_386_RELATIVE:
case elfcpp::R_386_IRELATIVE:
case elfcpp::R_386_TLS_TPOFF:
case elfcpp::R_386_TLS_DTPMOD32:
case elfcpp::R_386_TLS_DTPOFF32:
case elfcpp::R_386_TLS_TPOFF32:
case elfcpp::R_386_TLS_DESC:
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_386_TLS_GD: // Global-dynamic
case elfcpp::R_386_TLS_GOTDESC: // Global-dynamic (from ~oliva url)
case elfcpp::R_386_TLS_DESC_CALL:
case elfcpp::R_386_TLS_LDM: // Local-dynamic
case elfcpp::R_386_TLS_LDO_32: // Alternate local-dynamic
case elfcpp::R_386_TLS_IE: // Initial-exec
case elfcpp::R_386_TLS_IE_32:
case elfcpp::R_386_TLS_GOTIE:
case elfcpp::R_386_TLS_LE: // Local-exec
case elfcpp::R_386_TLS_LE_32:
{
bool output_is_shared = parameters->options().shared();
const tls::Tls_optimization optimized_type
= Target_i386::optimize_tls_reloc(!output_is_shared, r_type);
switch (r_type)
{
case elfcpp::R_386_TLS_GD: // Global-dynamic
if (optimized_type == tls::TLSOPT_NONE)
{
// Create a pair of GOT entries for the module index and
// dtv-relative offset.
Output_data_got<32, false>* got
= target->got_section(symtab, layout);
unsigned int r_sym = elfcpp::elf_r_sym<32>(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->rel_dyn_section(layout),
elfcpp::R_386_TLS_DTPMOD32);
}
else if (optimized_type != tls::TLSOPT_TO_LE)
unsupported_reloc_local(object, r_type);
break;
case elfcpp::R_386_TLS_GOTDESC: // Global-dynamic (from ~oliva)
target->define_tls_base_symbol(symtab, layout);
if (optimized_type == tls::TLSOPT_NONE)
{
// Create a double GOT entry with an R_386_TLS_DESC
// reloc. The R_386_TLS_DESC 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<32, false>* got = target->got_tlsdesc_section();
unsigned int r_sym = elfcpp::elf_r_sym<32>(reloc.get_r_info());
if (!object->local_has_got_offset(r_sym, GOT_TYPE_TLS_DESC))
{
unsigned int got_offset = got->add_constant(0);
// The local symbol value is stored in the second
// GOT entry.
got->add_local(object, r_sym, GOT_TYPE_TLS_DESC);
// That set the GOT offset of the local symbol to
// point to the second entry, but we want it to
// point to the first.
object->set_local_got_offset(r_sym, GOT_TYPE_TLS_DESC,
got_offset);
Reloc_section* rt = target->rel_tls_desc_section(layout);
rt->add_absolute(elfcpp::R_386_TLS_DESC, got, got_offset);
}
}
else if (optimized_type != tls::TLSOPT_TO_LE)
unsupported_reloc_local(object, r_type);
break;
case elfcpp::R_386_TLS_DESC_CALL:
break;
case elfcpp::R_386_TLS_LDM: // 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_386_TLS_LDO_32: // Alternate local-dynamic
break;
case elfcpp::R_386_TLS_IE: // Initial-exec
case elfcpp::R_386_TLS_IE_32:
case elfcpp::R_386_TLS_GOTIE:
layout->set_has_static_tls();
if (optimized_type == tls::TLSOPT_NONE)
{
// For the R_386_TLS_IE relocation, we need to create a
// dynamic relocation when building a shared library.
if (r_type == elfcpp::R_386_TLS_IE
&& parameters->options().shared())
{
Reloc_section* rel_dyn = target->rel_dyn_section(layout);
unsigned int r_sym
= elfcpp::elf_r_sym<32>(reloc.get_r_info());
rel_dyn->add_local_relative(object, r_sym,
elfcpp::R_386_RELATIVE,
output_section, data_shndx,
reloc.get_r_offset());
}
// Create a GOT entry for the tp-relative offset.
Output_data_got<32, false>* got
= target->got_section(symtab, layout);
unsigned int r_sym = elfcpp::elf_r_sym<32>(reloc.get_r_info());
unsigned int dyn_r_type = (r_type == elfcpp::R_386_TLS_IE_32
? elfcpp::R_386_TLS_TPOFF32
: elfcpp::R_386_TLS_TPOFF);
unsigned int got_type = (r_type == elfcpp::R_386_TLS_IE_32
? GOT_TYPE_TLS_OFFSET
: GOT_TYPE_TLS_NOFFSET);
got->add_local_with_rel(object, r_sym, got_type,
target->rel_dyn_section(layout),
dyn_r_type);
}
else if (optimized_type != tls::TLSOPT_TO_LE)
unsupported_reloc_local(object, r_type);
break;
case elfcpp::R_386_TLS_LE: // Local-exec
case elfcpp::R_386_TLS_LE_32:
layout->set_has_static_tls();
if (output_is_shared)
{
// We need to create a dynamic relocation.
gold_assert(lsym.get_st_type() != elfcpp::STT_SECTION);
unsigned int r_sym = elfcpp::elf_r_sym<32>(reloc.get_r_info());
unsigned int dyn_r_type = (r_type == elfcpp::R_386_TLS_LE_32
? elfcpp::R_386_TLS_TPOFF32
: elfcpp::R_386_TLS_TPOFF);
Reloc_section* rel_dyn = target->rel_dyn_section(layout);
rel_dyn->add_local(object, r_sym, dyn_r_type, output_section,
data_shndx, reloc.get_r_offset());
}
break;
default:
gold_unreachable();
}
}
break;
case elfcpp::R_386_32PLT:
case elfcpp::R_386_TLS_GD_32:
case elfcpp::R_386_TLS_GD_PUSH:
case elfcpp::R_386_TLS_GD_CALL:
case elfcpp::R_386_TLS_GD_POP:
case elfcpp::R_386_TLS_LDM_32:
case elfcpp::R_386_TLS_LDM_PUSH:
case elfcpp::R_386_TLS_LDM_CALL:
case elfcpp::R_386_TLS_LDM_POP:
case elfcpp::R_386_USED_BY_INTEL_200:
default:
unsupported_reloc_local(object, r_type);
break;
}
}
// Report an unsupported relocation against a global symbol.
void
Target_i386::Scan::unsupported_reloc_global(
Sized_relobj_file<32, 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());
}
inline bool
Target_i386::Scan::possible_function_pointer_reloc(unsigned int r_type)
{
switch (r_type)
{
case elfcpp::R_386_32:
case elfcpp::R_386_16:
case elfcpp::R_386_8:
case elfcpp::R_386_GOTOFF:
case elfcpp::R_386_GOT32:
{
return true;
}
default:
return false;
}
return false;
}
inline bool
Target_i386::Scan::local_reloc_may_be_function_pointer(
Symbol_table* ,
Layout* ,
Target_i386* ,
Sized_relobj_file<32, false>* ,
unsigned int ,
Output_section* ,
const elfcpp::Rel<32, false>& ,
unsigned int r_type,
const elfcpp::Sym<32, false>&)
{
return possible_function_pointer_reloc(r_type);
}
inline bool
Target_i386::Scan::global_reloc_may_be_function_pointer(
Symbol_table* ,
Layout* ,
Target_i386* ,
Sized_relobj_file<32, false>* ,
unsigned int ,
Output_section* ,
const elfcpp::Rel<32, false>& ,
unsigned int r_type,
Symbol*)
{
return possible_function_pointer_reloc(r_type);
}
// Scan a relocation for a global symbol.
inline void
Target_i386::Scan::global(Symbol_table* symtab,
Layout* layout,
Target_i386* target,
Sized_relobj_file<32, false>* object,
unsigned int data_shndx,
Output_section* output_section,
const elfcpp::Rel<32, 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_386_NONE:
case elfcpp::R_386_GNU_VTINHERIT:
case elfcpp::R_386_GNU_VTENTRY:
break;
case elfcpp::R_386_32:
case elfcpp::R_386_16:
case elfcpp::R_386_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 (r_type == elfcpp::R_386_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* rel_dyn = target->rel_irelative_section(layout);
rel_dyn->add_symbolless_global_addend(gsym,
elfcpp::R_386_IRELATIVE,
output_section,
object, data_shndx,
reloc.get_r_offset());
}
else if (r_type == elfcpp::R_386_32
&& gsym->can_use_relative_reloc(false))
{
Reloc_section* rel_dyn = target->rel_dyn_section(layout);
rel_dyn->add_global_relative(gsym, elfcpp::R_386_RELATIVE,
output_section, object,
data_shndx, reloc.get_r_offset());
}
else
{
Reloc_section* rel_dyn = target->rel_dyn_section(layout);
rel_dyn->add_global(gsym, r_type, output_section, object,
data_shndx, reloc.get_r_offset());
}
}
}
break;
case elfcpp::R_386_PC32:
case elfcpp::R_386_PC16:
case elfcpp::R_386_PC8:
{
// Make a PLT entry if necessary.
if (gsym->needs_plt_entry())
{
// These relocations are used for function calls only in
// non-PIC code. For a 32-bit relocation in a shared library,
// we'll need a text relocation anyway, so we can skip the
// PLT entry and let the dynamic linker bind the call directly
// to the target. For smaller relocations, we should use a
// PLT entry to ensure that the call can reach.
if (!parameters->options().shared()
|| r_type != elfcpp::R_386_PC32)
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
{
Reloc_section* rel_dyn = target->rel_dyn_section(layout);
rel_dyn->add_global(gsym, r_type, output_section, object,
data_shndx, reloc.get_r_offset());
}
}
}
break;
case elfcpp::R_386_GOT32:
{
// The symbol requires a GOT entry.
Output_data_got<32, 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
// GOT entry with a dynamic relocation.
Reloc_section* rel_dyn = target->rel_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,
rel_dyn, elfcpp::R_386_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);
rel_dyn->add_global_relative(gsym, elfcpp::R_386_RELATIVE,
got, got_off);
}
}
}
}
break;
case elfcpp::R_386_PLT32:
// 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_386_GOTOFF:
case elfcpp::R_386_GOTPC:
// We need a GOT section.
target->got_section(symtab, layout);
break;
// These are relocations which should only be seen by the
// dynamic linker, and should never be seen here.
case elfcpp::R_386_COPY:
case elfcpp::R_386_GLOB_DAT:
case elfcpp::R_386_JUMP_SLOT:
case elfcpp::R_386_RELATIVE:
case elfcpp::R_386_IRELATIVE:
case elfcpp::R_386_TLS_TPOFF:
case elfcpp::R_386_TLS_DTPMOD32:
case elfcpp::R_386_TLS_DTPOFF32:
case elfcpp::R_386_TLS_TPOFF32:
case elfcpp::R_386_TLS_DESC:
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_386_TLS_GD: // Global-dynamic
case elfcpp::R_386_TLS_GOTDESC: // Global-dynamic (from ~oliva url)
case elfcpp::R_386_TLS_DESC_CALL:
case elfcpp::R_386_TLS_LDM: // Local-dynamic
case elfcpp::R_386_TLS_LDO_32: // Alternate local-dynamic
case elfcpp::R_386_TLS_IE: // Initial-exec
case elfcpp::R_386_TLS_IE_32:
case elfcpp::R_386_TLS_GOTIE:
case elfcpp::R_386_TLS_LE: // Local-exec
case elfcpp::R_386_TLS_LE_32:
{
const bool is_final = gsym->final_value_is_known();
const tls::Tls_optimization optimized_type
= Target_i386::optimize_tls_reloc(is_final, r_type);
switch (r_type)
{
case elfcpp::R_386_TLS_GD: // Global-dynamic
if (optimized_type == tls::TLSOPT_NONE)
{
// Create a pair of GOT entries for the module index and
// dtv-relative offset.
Output_data_got<32, false>* got
= target->got_section(symtab, layout);
got->add_global_pair_with_rel(gsym, GOT_TYPE_TLS_PAIR,
target->rel_dyn_section(layout),
elfcpp::R_386_TLS_DTPMOD32,
elfcpp::R_386_TLS_DTPOFF32);
}
else if (optimized_type == tls::TLSOPT_TO_IE)
{
// Create a GOT entry for the tp-relative offset.
Output_data_got<32, false>* got
= target->got_section(symtab, layout);
got->add_global_with_rel(gsym, GOT_TYPE_TLS_NOFFSET,
target->rel_dyn_section(layout),
elfcpp::R_386_TLS_TPOFF);
}
else if (optimized_type != tls::TLSOPT_TO_LE)
unsupported_reloc_global(object, r_type, gsym);
break;
case elfcpp::R_386_TLS_GOTDESC: // Global-dynamic (~oliva url)
target->define_tls_base_symbol(symtab, layout);
if (optimized_type == tls::TLSOPT_NONE)
{
// Create a double GOT entry with an R_386_TLS_DESC
// reloc. The R_386_TLS_DESC 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<32, false>* got = target->got_tlsdesc_section();
Reloc_section* rt = target->rel_tls_desc_section(layout);
got->add_global_pair_with_rel(gsym, GOT_TYPE_TLS_DESC, rt,
elfcpp::R_386_TLS_DESC, 0);
}
else if (optimized_type == tls::TLSOPT_TO_IE)
{
// Create a GOT entry for the tp-relative offset.
Output_data_got<32, false>* got
= target->got_section(symtab, layout);
got->add_global_with_rel(gsym, GOT_TYPE_TLS_NOFFSET,
target->rel_dyn_section(layout),
elfcpp::R_386_TLS_TPOFF);
}
else if (optimized_type != tls::TLSOPT_TO_LE)
unsupported_reloc_global(object, r_type, gsym);
break;
case elfcpp::R_386_TLS_DESC_CALL:
break;
case elfcpp::R_386_TLS_LDM: // 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_386_TLS_LDO_32: // Alternate local-dynamic
break;
case elfcpp::R_386_TLS_IE: // Initial-exec
case elfcpp::R_386_TLS_IE_32:
case elfcpp::R_386_TLS_GOTIE:
layout->set_has_static_tls();
if (optimized_type == tls::TLSOPT_NONE)
{
// For the R_386_TLS_IE relocation, we need to create a
// dynamic relocation when building a shared library.
if (r_type == elfcpp::R_386_TLS_IE
&& parameters->options().shared())
{
Reloc_section* rel_dyn = target->rel_dyn_section(layout);
rel_dyn->add_global_relative(gsym, elfcpp::R_386_RELATIVE,
output_section, object,
data_shndx,
reloc.get_r_offset());
}
// Create a GOT entry for the tp-relative offset.
Output_data_got<32, false>* got
= target->got_section(symtab, layout);
unsigned int dyn_r_type = (r_type == elfcpp::R_386_TLS_IE_32
? elfcpp::R_386_TLS_TPOFF32
: elfcpp::R_386_TLS_TPOFF);
unsigned int got_type = (r_type == elfcpp::R_386_TLS_IE_32
? GOT_TYPE_TLS_OFFSET
: GOT_TYPE_TLS_NOFFSET);
got->add_global_with_rel(gsym, got_type,
target->rel_dyn_section(layout),
dyn_r_type);
}
else if (optimized_type != tls::TLSOPT_TO_LE)
unsupported_reloc_global(object, r_type, gsym);
break;
case elfcpp::R_386_TLS_LE: // Local-exec
case elfcpp::R_386_TLS_LE_32:
layout->set_has_static_tls();
if (parameters->options().shared())
{
// We need to create a dynamic relocation.
unsigned int dyn_r_type = (r_type == elfcpp::R_386_TLS_LE_32
? elfcpp::R_386_TLS_TPOFF32
: elfcpp::R_386_TLS_TPOFF);
Reloc_section* rel_dyn = target->rel_dyn_section(layout);
rel_dyn->add_global(gsym, dyn_r_type, output_section, object,
data_shndx, reloc.get_r_offset());
}
break;
default:
gold_unreachable();
}
}
break;
case elfcpp::R_386_32PLT:
case elfcpp::R_386_TLS_GD_32:
case elfcpp::R_386_TLS_GD_PUSH:
case elfcpp::R_386_TLS_GD_CALL:
case elfcpp::R_386_TLS_GD_POP:
case elfcpp::R_386_TLS_LDM_32:
case elfcpp::R_386_TLS_LDM_PUSH:
case elfcpp::R_386_TLS_LDM_CALL:
case elfcpp::R_386_TLS_LDM_POP:
case elfcpp::R_386_USED_BY_INTEL_200:
default:
unsupported_reloc_global(object, r_type, gsym);
break;
}
}
// Process relocations for gc.
void
Target_i386::gc_process_relocs(Symbol_table* symtab,
Layout* layout,
Sized_relobj_file<32, false>* object,
unsigned int data_shndx,
unsigned int,
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)
{
gold::gc_process_relocs<32, false, Target_i386, elfcpp::SHT_REL,
Target_i386::Scan,
Target_i386::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.
void
Target_i386::scan_relocs(Symbol_table* symtab,
Layout* layout,
Sized_relobj_file<32, 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_RELA)
{
gold_error(_("%s: unsupported RELA reloc section"),
object->name().c_str());
return;
}
gold::scan_relocs<32, false, Target_i386, elfcpp::SHT_REL,
Target_i386::Scan>(
symtab,
layout,
this,
object,
data_shndx,
prelocs,
reloc_count,
output_section,
needs_special_offset_handling,
local_symbol_count,
plocal_symbols);
}
// Finalize the sections.
void
Target_i386::do_finalize_sections(
Layout* layout,
const Input_objects*,
Symbol_table* symtab)
{
const Reloc_section* rel_plt = (this->plt_ == NULL
? NULL
: this->plt_->rel_plt());
layout->add_target_dynamic_tags(true, this->got_plt_, rel_plt,
this->rel_dyn_, true, false);
// 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->rel_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)
{
uint32_t data_size = this->got_plt_->current_data_size();
symtab->get_sized_symbol<32>(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 __rel_iplt symbols
// were defined if necessary, even if we didn't create a PLT.
static const Define_symbol_in_segment syms[] =
{
{
"__rel_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
},
{
"__rel_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());
}
}
// Return whether a direct absolute static relocation needs to be applied.
// In cases where Scan::local() or Scan::global() has created
// a dynamic relocation other than R_386_RELATIVE, the addend
// of the relocation is carried in the data, and we must not
// apply the static relocation.
inline bool
Target_i386::Relocate::should_apply_static_reloc(const Sized_symbol<32>* gsym,
unsigned int r_type,
bool is_32bit,
Output_section* output_section)
{
// If the output section is not allocated, then we didn't call
// scan_relocs, we didn't create a dynamic reloc, and we must apply
// the reloc here.
if ((output_section->flags() & elfcpp::SHF_ALLOC) == 0)
return true;
int ref_flags = Scan::get_reference_flags(r_type);
// For local symbols, we will have created a non-RELATIVE dynamic
// relocation only if (a) the output is position independent,
// (b) the relocation is absolute (not pc- or segment-relative), and
// (c) the relocation is not 32 bits wide.
if (gsym == NULL)
return !(parameters->options().output_is_position_independent()
&& (ref_flags & Symbol::ABSOLUTE_REF)
&& !is_32bit);
// For global symbols, we use the same helper routines used in the
// scan pass. If we did not create a dynamic relocation, or if we
// created a RELATIVE dynamic relocation, we should apply the static
// relocation.
bool has_dyn = gsym->needs_dynamic_reloc(ref_flags);
bool is_rel = (ref_flags & Symbol::ABSOLUTE_REF)
&& gsym->can_use_relative_reloc(ref_flags
& Symbol::FUNCTION_CALL);
return !has_dyn || is_rel;
}
// Perform a relocation.
inline bool
Target_i386::Relocate::relocate(const Relocate_info<32, false>* relinfo,
Target_i386* target,
Output_section* output_section,
size_t relnum,
const elfcpp::Rel<32, false>& rel,
unsigned int r_type,
const Sized_symbol<32>* gsym,
const Symbol_value<32>* psymval,
unsigned char* view,
elfcpp::Elf_types<32>::Elf_Addr address,
section_size_type view_size)
{
if (this->skip_call_tls_get_addr_)
{
if ((r_type != elfcpp::R_386_PLT32
&& r_type != elfcpp::R_386_PC32)
|| gsym == NULL
|| strcmp(gsym->name(), "___tls_get_addr") != 0)
gold_error_at_location(relinfo, relnum, rel.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<32, false>* object = relinfo->object;
// Pick the value to use for symbols defined in shared objects.
Symbol_value<32> symval;
if (gsym != NULL
&& gsym->type() == elfcpp::STT_GNU_IFUNC
&& r_type == elfcpp::R_386_32
&& gsym->needs_dynamic_reloc(Scan::get_reference_flags(r_type))
&& gsym->can_use_relative_reloc(false)
&& !gsym->is_from_dynobj()
&& !gsym->is_undefined()
&& !gsym->is_preemptible())
{
// In this case we are generating a R_386_IRELATIVE reloc. We
// want to use the real value of the symbol, not the PLT offset.
}
else 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<32>(rel.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;
}
}
// 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_386_GOT32:
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<32>(rel.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_386_NONE:
case elfcpp::R_386_GNU_VTINHERIT:
case elfcpp::R_386_GNU_VTENTRY:
break;
case elfcpp::R_386_32:
if (should_apply_static_reloc(gsym, r_type, true, output_section))
Relocate_functions<32, false>::rel32(view, object, psymval);
break;
case elfcpp::R_386_PC32:
if (should_apply_static_reloc(gsym, r_type, true, output_section))
Relocate_functions<32, false>::pcrel32(view, object, psymval, address);
break;
case elfcpp::R_386_16:
if (should_apply_static_reloc(gsym, r_type, false, output_section))
Relocate_functions<32, false>::rel16(view, object, psymval);
break;
case elfcpp::R_386_PC16:
if (should_apply_static_reloc(gsym, r_type, false, output_section))
Relocate_functions<32, false>::pcrel16(view, object, psymval, address);
break;
case elfcpp::R_386_8:
if (should_apply_static_reloc(gsym, r_type, false, output_section))
Relocate_functions<32, false>::rel8(view, object, psymval);
break;
case elfcpp::R_386_PC8:
if (should_apply_static_reloc(gsym, r_type, false, output_section))
Relocate_functions<32, false>::pcrel8(view, object, psymval, address);
break;
case elfcpp::R_386_PLT32:
gold_assert(gsym == NULL
|| gsym->has_plt_offset()
|| gsym->final_value_is_known()
|| (gsym->is_defined()
&& !gsym->is_from_dynobj()
&& !gsym->is_preemptible()));
Relocate_functions<32, false>::pcrel32(view, object, psymval, address);
break;
case elfcpp::R_386_GOT32:
gold_assert(have_got_offset);
Relocate_functions<32, false>::rel32(view, got_offset);
break;
case elfcpp::R_386_GOTOFF:
{
elfcpp::Elf_types<32>::Elf_Addr value;
value = (psymval->value(object, 0)
- target->got_plt_section()->address());
Relocate_functions<32, false>::rel32(view, value);
}
break;
case elfcpp::R_386_GOTPC:
{
elfcpp::Elf_types<32>::Elf_Addr value;
value = target->got_plt_section()->address();
Relocate_functions<32, false>::pcrel32(view, value, address);
}
break;
case elfcpp::R_386_COPY:
case elfcpp::R_386_GLOB_DAT:
case elfcpp::R_386_JUMP_SLOT:
case elfcpp::R_386_RELATIVE:
case elfcpp::R_386_IRELATIVE:
// These are outstanding tls relocs, which are unexpected when
// linking.
case elfcpp::R_386_TLS_TPOFF:
case elfcpp::R_386_TLS_DTPMOD32:
case elfcpp::R_386_TLS_DTPOFF32:
case elfcpp::R_386_TLS_TPOFF32:
case elfcpp::R_386_TLS_DESC:
gold_error_at_location(relinfo, relnum, rel.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_386_TLS_GD: // Global-dynamic
case elfcpp::R_386_TLS_GOTDESC: // Global-dynamic (from ~oliva url)
case elfcpp::R_386_TLS_DESC_CALL:
case elfcpp::R_386_TLS_LDM: // Local-dynamic
case elfcpp::R_386_TLS_LDO_32: // Alternate local-dynamic
case elfcpp::R_386_TLS_IE: // Initial-exec
case elfcpp::R_386_TLS_IE_32:
case elfcpp::R_386_TLS_GOTIE:
case elfcpp::R_386_TLS_LE: // Local-exec
case elfcpp::R_386_TLS_LE_32:
this->relocate_tls(relinfo, target, relnum, rel, r_type, gsym, psymval,
view, address, view_size);
break;
case elfcpp::R_386_32PLT:
case elfcpp::R_386_TLS_GD_32:
case elfcpp::R_386_TLS_GD_PUSH:
case elfcpp::R_386_TLS_GD_CALL:
case elfcpp::R_386_TLS_GD_POP:
case elfcpp::R_386_TLS_LDM_32:
case elfcpp::R_386_TLS_LDM_PUSH:
case elfcpp::R_386_TLS_LDM_CALL:
case elfcpp::R_386_TLS_LDM_POP:
case elfcpp::R_386_USED_BY_INTEL_200:
default:
gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
_("unsupported reloc %u"),
r_type);
break;
}
return true;
}
// Perform a TLS relocation.
inline void
Target_i386::Relocate::relocate_tls(const Relocate_info<32, false>* relinfo,
Target_i386* target,
size_t relnum,
const elfcpp::Rel<32, false>& rel,
unsigned int r_type,
const Sized_symbol<32>* gsym,
const Symbol_value<32>* psymval,
unsigned char* view,
elfcpp::Elf_types<32>::Elf_Addr,
section_size_type view_size)
{
Output_segment* tls_segment = relinfo->layout->tls_segment();
const Sized_relobj_file<32, false>* object = relinfo->object;
elfcpp::Elf_types<32>::Elf_Addr value = psymval->value(object, 0);
const bool is_final = (gsym == NULL
? !parameters->options().shared()
: gsym->final_value_is_known());
const tls::Tls_optimization optimized_type
= Target_i386::optimize_tls_reloc(is_final, r_type);
switch (r_type)
{
case elfcpp::R_386_TLS_GD: // Global-dynamic
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,
rel, r_type, value, view,
view_size);
break;
}
else
{
unsigned int got_type = (optimized_type == tls::TLSOPT_TO_IE
? GOT_TYPE_TLS_NOFFSET
: 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<32>(rel.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)
{
this->tls_gd_to_ie(relinfo, relnum, tls_segment, rel, r_type,
got_offset, view, view_size);
break;
}
else if (optimized_type == tls::TLSOPT_NONE)
{
// Relocate the field with the offset of the pair of GOT
// entries.
Relocate_functions<32, false>::rel32(view, got_offset);
break;
}
}
gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
_("unsupported reloc %u"),
r_type);
break;
case elfcpp::R_386_TLS_GOTDESC: // Global-dynamic (from ~oliva url)
case elfcpp::R_386_TLS_DESC_CALL:
this->local_dynamic_type_ = LOCAL_DYNAMIC_GNU;
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,
rel, r_type, value, view,
view_size);
break;
}
else
{
unsigned int got_type = (optimized_type == tls::TLSOPT_TO_IE
? GOT_TYPE_TLS_NOFFSET
: GOT_TYPE_TLS_DESC);
unsigned int got_offset = 0;
if (r_type == elfcpp::R_386_TLS_GOTDESC
&& 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<32>(rel.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;
}
this->tls_desc_gd_to_ie(relinfo, relnum, tls_segment, rel, r_type,
got_offset, view, view_size);
break;
}
else if (optimized_type == tls::TLSOPT_NONE)
{
if (r_type == elfcpp::R_386_TLS_GOTDESC)
{
// Relocate the field with the offset of the pair of GOT
// entries.
Relocate_functions<32, false>::rel32(view, got_offset);
}
break;
}
}
gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
_("unsupported reloc %u"),
r_type);
break;
case elfcpp::R_386_TLS_LDM: // Local-dynamic
if (this->local_dynamic_type_ == LOCAL_DYNAMIC_SUN)
{
gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
_("both SUN and GNU model "
"TLS relocations"));
break;
}
this->local_dynamic_type_ = LOCAL_DYNAMIC_GNU;
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, rel, 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());
Relocate_functions<32, false>::rel32(view, got_offset);
break;
}
gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
_("unsupported reloc %u"),
r_type);
break;
case elfcpp::R_386_TLS_LDO_32: // Alternate local-dynamic
if (optimized_type == tls::TLSOPT_TO_LE)
{
// This reloc can appear in debugging sections, in which
// case we must not convert to local-exec. We decide what
// to do based on whether the section is marked as
// containing executable code. That is what the GNU linker
// does as well.
elfcpp::Shdr<32, false> shdr(relinfo->data_shdr);
if ((shdr.get_sh_flags() & elfcpp::SHF_EXECINSTR) != 0)
{
if (tls_segment == NULL)
{
gold_assert(parameters->errors()->error_count() > 0
|| issue_undefined_symbol_error(gsym));
return;
}
value -= tls_segment->memsz();
}
}
Relocate_functions<32, false>::rel32(view, value);
break;
case elfcpp::R_386_TLS_IE: // Initial-exec
case elfcpp::R_386_TLS_GOTIE:
case elfcpp::R_386_TLS_IE_32:
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_i386::Relocate::tls_ie_to_le(relinfo, relnum, tls_segment,
rel, 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_type = (r_type == elfcpp::R_386_TLS_IE_32
? GOT_TYPE_TLS_OFFSET
: GOT_TYPE_TLS_NOFFSET);
unsigned int got_offset;
if (gsym != NULL)
{
gold_assert(gsym->has_got_offset(got_type));
got_offset = gsym->got_offset(got_type);
}
else
{
unsigned int r_sym = elfcpp::elf_r_sym<32>(rel.get_r_info());
gold_assert(object->local_has_got_offset(r_sym, got_type));
got_offset = object->local_got_offset(r_sym, got_type);
}
// For the R_386_TLS_IE relocation, we need to apply the
// absolute address of the GOT entry.
if (r_type == elfcpp::R_386_TLS_IE)
got_offset += target->got_plt_section()->address();
// All GOT offsets are relative to the end of the GOT.
got_offset -= target->got_size();
Relocate_functions<32, false>::rel32(view, got_offset);
break;
}
gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
_("unsupported reloc %u"),
r_type);
break;
case elfcpp::R_386_TLS_LE: // Local-exec
// If we're creating a shared library, a dynamic relocation will
// have been created for this location, so do not apply it now.
if (!parameters->options().shared())
{
if (tls_segment == NULL)
{
gold_assert(parameters->errors()->error_count() > 0
|| issue_undefined_symbol_error(gsym));
return;
}
value -= tls_segment->memsz();
Relocate_functions<32, false>::rel32(view, value);
}
break;
case elfcpp::R_386_TLS_LE_32:
// If we're creating a shared library, a dynamic relocation will
// have been created for this location, so do not apply it now.
if (!parameters->options().shared())
{
if (tls_segment == NULL)
{
gold_assert(parameters->errors()->error_count() > 0
|| issue_undefined_symbol_error(gsym));
return;
}
value = tls_segment->memsz() - value;
Relocate_functions<32, false>::rel32(view, value);
}
break;
}
}
// Do a relocation in which we convert a TLS General-Dynamic to a
// Local-Exec.
inline void
Target_i386::Relocate::tls_gd_to_le(const Relocate_info<32, false>* relinfo,
size_t relnum,
Output_segment* tls_segment,
const elfcpp::Rel<32, false>& rel,
unsigned int,
elfcpp::Elf_types<32>::Elf_Addr value,
unsigned char* view,
section_size_type view_size)
{
// leal foo(,%reg,1),%eax; call ___tls_get_addr
// ==> movl %gs:0,%eax; subl $foo@tpoff,%eax
// leal foo(%reg),%eax; call ___tls_get_addr
// ==> movl %gs:0,%eax; subl $foo@tpoff,%eax
tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2);
tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 9);
unsigned char op1 = view[-1];
unsigned char op2 = view[-2];
tls::check_tls(relinfo, relnum, rel.get_r_offset(),
op2 == 0x8d || op2 == 0x04);
tls::check_tls(relinfo, relnum, rel.get_r_offset(), view[4] == 0xe8);
int roff = 5;
if (op2 == 0x04)
{
tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -3);
tls::check_tls(relinfo, relnum, rel.get_r_offset(), view[-3] == 0x8d);
tls::check_tls(relinfo, relnum, rel.get_r_offset(),
((op1 & 0xc7) == 0x05 && op1 != (4 << 3)));
memcpy(view - 3, "\x65\xa1\0\0\0\0\x81\xe8\0\0\0", 12);
}
else
{
tls::check_tls(relinfo, relnum, rel.get_r_offset(),
(op1 & 0xf8) == 0x80 && (op1 & 7) != 4);
if (rel.get_r_offset() + 9 < view_size
&& view[9] == 0x90)
{
// There is a trailing nop. Use the size byte subl.
memcpy(view - 2, "\x65\xa1\0\0\0\0\x81\xe8\0\0\0", 12);
roff = 6;
}
else
{
// Use the five byte subl.
memcpy(view - 2, "\x65\xa1\0\0\0\0\x2d\0\0\0", 11);
}
}
value = tls_segment->memsz() - value;
Relocate_functions<32, false>::rel32(view + roff, value);
// 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 an
// Initial-Exec.
inline void
Target_i386::Relocate::tls_gd_to_ie(const Relocate_info<32, false>* relinfo,
size_t relnum,
Output_segment*,
const elfcpp::Rel<32, false>& rel,
unsigned int,
elfcpp::Elf_types<32>::Elf_Addr value,
unsigned char* view,
section_size_type view_size)
{
// leal foo(,%ebx,1),%eax; call ___tls_get_addr
// ==> movl %gs:0,%eax; addl foo@gotntpoff(%ebx),%eax
tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2);
tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 9);
unsigned char op1 = view[-1];
unsigned char op2 = view[-2];
tls::check_tls(relinfo, relnum, rel.get_r_offset(),
op2 == 0x8d || op2 == 0x04);
tls::check_tls(relinfo, relnum, rel.get_r_offset(), view[4] == 0xe8);
int roff = 5;
// FIXME: For now, support only the first (SIB) form.
tls::check_tls(relinfo, relnum, rel.get_r_offset(), op2 == 0x04);
if (op2 == 0x04)
{
tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -3);
tls::check_tls(relinfo, relnum, rel.get_r_offset(), view[-3] == 0x8d);
tls::check_tls(relinfo, relnum, rel.get_r_offset(),
((op1 & 0xc7) == 0x05 && op1 != (4 << 3)));
memcpy(view - 3, "\x65\xa1\0\0\0\0\x03\x83\0\0\0", 12);
}
else
{
tls::check_tls(relinfo, relnum, rel.get_r_offset(),
(op1 & 0xf8) == 0x80 && (op1 & 7) != 4);
if (rel.get_r_offset() + 9 < view_size
&& view[9] == 0x90)
{
// FIXME: This is not the right instruction sequence.
// There is a trailing nop. Use the size byte subl.
memcpy(view - 2, "\x65\xa1\0\0\0\0\x81\xe8\0\0\0", 12);
roff = 6;
}
else
{
// FIXME: This is not the right instruction sequence.
// Use the five byte subl.
memcpy(view - 2, "\x65\xa1\0\0\0\0\x2d\0\0\0", 11);
}
}
Relocate_functions<32, false>::rel32(view + roff, value);
// 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_GOTDESC or TLS_DESC_CALL
// General-Dynamic to a Local-Exec.
inline void
Target_i386::Relocate::tls_desc_gd_to_le(
const Relocate_info<32, false>* relinfo,
size_t relnum,
Output_segment* tls_segment,
const elfcpp::Rel<32, false>& rel,
unsigned int r_type,
elfcpp::Elf_types<32>::Elf_Addr value,
unsigned char* view,
section_size_type view_size)
{
if (r_type == elfcpp::R_386_TLS_GOTDESC)
{
// leal foo@TLSDESC(%ebx), %eax
// ==> leal foo@NTPOFF, %eax
tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2);
tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 4);
tls::check_tls(relinfo, relnum, rel.get_r_offset(),
view[-2] == 0x8d && view[-1] == 0x83);
view[-1] = 0x05;
value -= tls_segment->memsz();
Relocate_functions<32, false>::rel32(view, value);
}
else
{
// call *foo@TLSCALL(%eax)
// ==> nop; nop
gold_assert(r_type == elfcpp::R_386_TLS_DESC_CALL);
tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 2);
tls::check_tls(relinfo, relnum, rel.get_r_offset(),
view[0] == 0xff && view[1] == 0x10);
view[0] = 0x66;
view[1] = 0x90;
}
}
// Do a relocation in which we convert a TLS_GOTDESC or TLS_DESC_CALL
// General-Dynamic to an Initial-Exec.
inline void
Target_i386::Relocate::tls_desc_gd_to_ie(
const Relocate_info<32, false>* relinfo,
size_t relnum,
Output_segment*,
const elfcpp::Rel<32, false>& rel,
unsigned int r_type,
elfcpp::Elf_types<32>::Elf_Addr value,
unsigned char* view,
section_size_type view_size)
{
if (r_type == elfcpp::R_386_TLS_GOTDESC)
{
// leal foo@TLSDESC(%ebx), %eax
// ==> movl foo@GOTNTPOFF(%ebx), %eax
tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2);
tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 4);
tls::check_tls(relinfo, relnum, rel.get_r_offset(),
view[-2] == 0x8d && view[-1] == 0x83);
view[-2] = 0x8b;
Relocate_functions<32, false>::rel32(view, value);
}
else
{
// call *foo@TLSCALL(%eax)
// ==> nop; nop
gold_assert(r_type == elfcpp::R_386_TLS_DESC_CALL);
tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 2);
tls::check_tls(relinfo, relnum, rel.get_r_offset(),
view[0] == 0xff && view[1] == 0x10);
view[0] = 0x66;
view[1] = 0x90;
}
}
// Do a relocation in which we convert a TLS Local-Dynamic to a
// Local-Exec.
inline void
Target_i386::Relocate::tls_ld_to_le(const Relocate_info<32, false>* relinfo,
size_t relnum,
Output_segment*,
const elfcpp::Rel<32, false>& rel,
unsigned int,
elfcpp::Elf_types<32>::Elf_Addr,
unsigned char* view,
section_size_type view_size)
{
// leal foo(%reg), %eax; call ___tls_get_addr
// ==> movl %gs:0,%eax; nop; leal 0(%esi,1),%esi
tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2);
tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 9);
// FIXME: Does this test really always pass?
tls::check_tls(relinfo, relnum, rel.get_r_offset(),
view[-2] == 0x8d && view[-1] == 0x83);
tls::check_tls(relinfo, relnum, rel.get_r_offset(), view[4] == 0xe8);
memcpy(view - 2, "\x65\xa1\0\0\0\0\x90\x8d\x74\x26\0", 11);
// 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.
inline void
Target_i386::Relocate::tls_ie_to_le(const Relocate_info<32, false>* relinfo,
size_t relnum,
Output_segment* tls_segment,
const elfcpp::Rel<32, false>& rel,
unsigned int r_type,
elfcpp::Elf_types<32>::Elf_Addr value,
unsigned char* view,
section_size_type view_size)
{
// We have to actually change the instructions, which means that we
// need to examine the opcodes to figure out which instruction we
// are looking at.
if (r_type == elfcpp::R_386_TLS_IE)
{
// movl %gs:XX,%eax ==> movl $YY,%eax
// movl %gs:XX,%reg ==> movl $YY,%reg
// addl %gs:XX,%reg ==> addl $YY,%reg
tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -1);
tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 4);
unsigned char op1 = view[-1];
if (op1 == 0xa1)
{
// movl XX,%eax ==> movl $YY,%eax
view[-1] = 0xb8;
}
else
{
tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2);
unsigned char op2 = view[-2];
if (op2 == 0x8b)
{
// movl XX,%reg ==> movl $YY,%reg
tls::check_tls(relinfo, relnum, rel.get_r_offset(),
(op1 & 0xc7) == 0x05);
view[-2] = 0xc7;
view[-1] = 0xc0 | ((op1 >> 3) & 7);
}
else if (op2 == 0x03)
{
// addl XX,%reg ==> addl $YY,%reg
tls::check_tls(relinfo, relnum, rel.get_r_offset(),
(op1 & 0xc7) == 0x05);
view[-2] = 0x81;
view[-1] = 0xc0 | ((op1 >> 3) & 7);
}
else
tls::check_tls(relinfo, relnum, rel.get_r_offset(), 0);
}
}
else
{
// subl %gs:XX(%reg1),%reg2 ==> subl $YY,%reg2
// movl %gs:XX(%reg1),%reg2 ==> movl $YY,%reg2
// addl %gs:XX(%reg1),%reg2 ==> addl $YY,$reg2
tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2);
tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 4);
unsigned char op1 = view[-1];
unsigned char op2 = view[-2];
tls::check_tls(relinfo, relnum, rel.get_r_offset(),
(op1 & 0xc0) == 0x80 && (op1 & 7) != 4);
if (op2 == 0x8b)
{
// movl %gs:XX(%reg1),%reg2 ==> movl $YY,%reg2
view[-2] = 0xc7;
view[-1] = 0xc0 | ((op1 >> 3) & 7);
}
else if (op2 == 0x2b)
{
// subl %gs:XX(%reg1),%reg2 ==> subl $YY,%reg2
view[-2] = 0x81;
view[-1] = 0xe8 | ((op1 >> 3) & 7);
}
else if (op2 == 0x03)
{
// addl %gs:XX(%reg1),%reg2 ==> addl $YY,$reg2
view[-2] = 0x81;
view[-1] = 0xc0 | ((op1 >> 3) & 7);
}
else
tls::check_tls(relinfo, relnum, rel.get_r_offset(), 0);
}
value = tls_segment->memsz() - value;
if (r_type == elfcpp::R_386_TLS_IE || r_type == elfcpp::R_386_TLS_GOTIE)
value = - value;
Relocate_functions<32, false>::rel32(view, value);
}
// Relocate section data.
void
Target_i386::relocate_section(const Relocate_info<32, 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,
elfcpp::Elf_types<32>::Elf_Addr address,
section_size_type view_size,
const Reloc_symbol_changes* reloc_symbol_changes)
{
gold_assert(sh_type == elfcpp::SHT_REL);
gold::relocate_section<32, false, Target_i386, elfcpp::SHT_REL,
Target_i386::Relocate, gold::Default_comdat_behavior>(
relinfo,
this,
prelocs,
reloc_count,
output_section,
needs_special_offset_handling,
view,
address,
view_size,
reloc_symbol_changes);
}
// Return the size of a relocation while scanning during a relocatable
// link.
unsigned int
Target_i386::Relocatable_size_for_reloc::get_size_for_reloc(
unsigned int r_type,
Relobj* object)
{
switch (r_type)
{
case elfcpp::R_386_NONE:
case elfcpp::R_386_GNU_VTINHERIT:
case elfcpp::R_386_GNU_VTENTRY:
case elfcpp::R_386_TLS_GD: // Global-dynamic
case elfcpp::R_386_TLS_GOTDESC: // Global-dynamic (from ~oliva url)
case elfcpp::R_386_TLS_DESC_CALL:
case elfcpp::R_386_TLS_LDM: // Local-dynamic
case elfcpp::R_386_TLS_LDO_32: // Alternate local-dynamic
case elfcpp::R_386_TLS_IE: // Initial-exec
case elfcpp::R_386_TLS_IE_32:
case elfcpp::R_386_TLS_GOTIE:
case elfcpp::R_386_TLS_LE: // Local-exec
case elfcpp::R_386_TLS_LE_32:
return 0;
case elfcpp::R_386_32:
case elfcpp::R_386_PC32:
case elfcpp::R_386_GOT32:
case elfcpp::R_386_PLT32:
case elfcpp::R_386_GOTOFF:
case elfcpp::R_386_GOTPC:
return 4;
case elfcpp::R_386_16:
case elfcpp::R_386_PC16:
return 2;
case elfcpp::R_386_8:
case elfcpp::R_386_PC8:
return 1;
// These are relocations which should only be seen by the
// dynamic linker, and should never be seen here.
case elfcpp::R_386_COPY:
case elfcpp::R_386_GLOB_DAT:
case elfcpp::R_386_JUMP_SLOT:
case elfcpp::R_386_RELATIVE:
case elfcpp::R_386_IRELATIVE:
case elfcpp::R_386_TLS_TPOFF:
case elfcpp::R_386_TLS_DTPMOD32:
case elfcpp::R_386_TLS_DTPOFF32:
case elfcpp::R_386_TLS_TPOFF32:
case elfcpp::R_386_TLS_DESC:
object->error(_("unexpected reloc %u in object file"), r_type);
return 0;
case elfcpp::R_386_32PLT:
case elfcpp::R_386_TLS_GD_32:
case elfcpp::R_386_TLS_GD_PUSH:
case elfcpp::R_386_TLS_GD_CALL:
case elfcpp::R_386_TLS_GD_POP:
case elfcpp::R_386_TLS_LDM_32:
case elfcpp::R_386_TLS_LDM_PUSH:
case elfcpp::R_386_TLS_LDM_CALL:
case elfcpp::R_386_TLS_LDM_POP:
case elfcpp::R_386_USED_BY_INTEL_200:
default:
object->error(_("unsupported reloc %u in object file"), r_type);
return 0;
}
}
// Scan the relocs during a relocatable link.
void
Target_i386::scan_relocatable_relocs(Symbol_table* symtab,
Layout* layout,
Sized_relobj_file<32, 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_REL);
typedef gold::Default_scan_relocatable_relocs<elfcpp::SHT_REL,
Relocatable_size_for_reloc> Scan_relocatable_relocs;
gold::scan_relocatable_relocs<32, false, elfcpp::SHT_REL,
Scan_relocatable_relocs>(
symtab,
layout,
object,
data_shndx,
prelocs,
reloc_count,
output_section,
needs_special_offset_handling,
local_symbol_count,
plocal_symbols,
rr);
}
// Emit relocations for a section.
void
Target_i386::relocate_relocs(
const Relocate_info<32, false>* relinfo,
unsigned int sh_type,
const unsigned char* prelocs,
size_t reloc_count,
Output_section* output_section,
elfcpp::Elf_types<32>::Elf_Off offset_in_output_section,
const Relocatable_relocs* rr,
unsigned char* view,
elfcpp::Elf_types<32>::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_REL);
gold::relocate_relocs<32, false, elfcpp::SHT_REL>(
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.
uint64_t
Target_i386::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.
std::string
Target_i386::do_code_fill(section_size_type length) const
{
if (length >= 16)
{
// Build a jmp 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] = { '\x8d', '\x76', '\x00' }; // leal 0(%esi),%esi
const char nop4[4] = { '\x8d', '\x74', '\x26', // leal 0(%esi,1),%esi
'\x00'};
const char nop5[5] = { '\x90', '\x8d', '\x74', // nop
'\x26', '\x00' }; // leal 0(%esi,1),%esi
const char nop6[6] = { '\x8d', '\xb6', '\x00', // leal 0L(%esi),%esi
'\x00', '\x00', '\x00' };
const char nop7[7] = { '\x8d', '\xb4', '\x26', // leal 0L(%esi,1),%esi
'\x00', '\x00', '\x00',
'\x00' };
const char nop8[8] = { '\x90', '\x8d', '\xb4', // nop
'\x26', '\x00', '\x00', // leal 0L(%esi,1),%esi
'\x00', '\x00' };
const char nop9[9] = { '\x89', '\xf6', '\x8d', // movl %esi,%esi
'\xbc', '\x27', '\x00', // leal 0L(%edi,1),%edi
'\x00', '\x00', '\x00' };
const char nop10[10] = { '\x8d', '\x76', '\x00', // leal 0(%esi),%esi
'\x8d', '\xbc', '\x27', // leal 0L(%edi,1),%edi
'\x00', '\x00', '\x00',
'\x00' };
const char nop11[11] = { '\x8d', '\x74', '\x26', // leal 0(%esi,1),%esi
'\x00', '\x8d', '\xbc', // leal 0L(%edi,1),%edi
'\x27', '\x00', '\x00',
'\x00', '\x00' };
const char nop12[12] = { '\x8d', '\xb6', '\x00', // leal 0L(%esi),%esi
'\x00', '\x00', '\x00', // leal 0L(%edi),%edi
'\x8d', '\xbf', '\x00',
'\x00', '\x00', '\x00' };
const char nop13[13] = { '\x8d', '\xb6', '\x00', // leal 0L(%esi),%esi
'\x00', '\x00', '\x00', // leal 0L(%edi,1),%edi
'\x8d', '\xbc', '\x27',
'\x00', '\x00', '\x00',
'\x00' };
const char nop14[14] = { '\x8d', '\xb4', '\x26', // leal 0L(%esi,1),%esi
'\x00', '\x00', '\x00', // leal 0L(%edi,1),%edi
'\x00', '\x8d', '\xbc',
'\x27', '\x00', '\x00',
'\x00', '\x00' };
const char nop15[15] = { '\xeb', '\x0d', '\x90', // jmp .+15
'\x90', '\x90', '\x90', // nop,nop,nop,...
'\x90', '\x90', '\x90',
'\x90', '\x90', '\x90',
'\x90', '\x90', '\x90' };
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 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.
uint64_t
Target_i386::do_ehframe_datarel_base() const
{
gold_assert(this->global_offset_table_ != NULL);
Symbol* sym = this->global_offset_table_;
Sized_symbol<32>* ssym = static_cast<Sized_symbol<32>*>(sym);
return ssym->value();
}
// Return whether SYM should be treated as a call to a non-split
// function. We don't want that to be true of a call to a
// get_pc_thunk function.
bool
Target_i386::do_is_call_to_non_split(const Symbol* sym, unsigned int) const
{
return (sym->type() == elfcpp::STT_FUNC
&& !is_prefix_of("__i686.get_pc_thunk.", sym->name()));
}
// 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.
void
Target_i386::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 %gs:NN,%esp
if (this->match_view(view, view_size, fnoffset, "\x65\x3b\x25", 3)
&& fnsize > 7)
{
// 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, 6);
}
// lea NN(%esp),%ecx
// lea NN(%esp),%edx
else if ((this->match_view(view, view_size, fnoffset, "\x8d\x8c\x24", 3)
|| this->match_view(view, view_size, fnoffset, "\x8d\x94\x24", 3))
&& fnsize > 7)
{
// 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 + 3;
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 i386 object files. Note this is never instantiated
// directly. It's only used in Target_selector_i386_nacl, below.
class Target_selector_i386 : public Target_selector_freebsd
{
public:
Target_selector_i386()
: Target_selector_freebsd(elfcpp::EM_386, 32, false,
"elf32-i386", "elf32-i386-freebsd",
"elf_i386")
{ }
Target*
do_instantiate_target()
{ return new Target_i386(); }
};
// NaCl variant. It uses different PLT contents.
class Output_data_plt_i386_nacl : public Output_data_plt_i386
{
public:
Output_data_plt_i386_nacl(Layout* layout,
Output_data_got_plt_i386* got_plt,
Output_data_space* got_irelative)
: Output_data_plt_i386(layout, plt_entry_size, got_plt, got_irelative)
{ }
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, plt_eh_frame_cie, plt_eh_frame_cie_size,
plt_eh_frame_fde, plt_eh_frame_fde_size);
}
// The size of an entry in the PLT.
static const int plt_entry_size = 64;
// 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];
};
class Output_data_plt_i386_nacl_exec : public Output_data_plt_i386_nacl
{
public:
Output_data_plt_i386_nacl_exec(Layout* layout,
Output_data_got_plt_i386* got_plt,
Output_data_space* got_irelative)
: Output_data_plt_i386_nacl(layout, got_plt, got_irelative)
{ }
protected:
virtual void
do_fill_first_plt_entry(unsigned char* pov,
elfcpp::Elf_types<32>::Elf_Addr got_address);
virtual unsigned int
do_fill_plt_entry(unsigned char* pov,
elfcpp::Elf_types<32>::Elf_Addr got_address,
unsigned int got_offset,
unsigned int plt_offset,
unsigned int plt_rel_offset);
private:
// The first entry in the PLT for an executable.
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];
};
class Output_data_plt_i386_nacl_dyn : public Output_data_plt_i386_nacl
{
public:
Output_data_plt_i386_nacl_dyn(Layout* layout,
Output_data_got_plt_i386* got_plt,
Output_data_space* got_irelative)
: Output_data_plt_i386_nacl(layout, got_plt, got_irelative)
{ }
protected:
virtual void
do_fill_first_plt_entry(unsigned char* pov, elfcpp::Elf_types<32>::Elf_Addr);
virtual unsigned int
do_fill_plt_entry(unsigned char* pov,
elfcpp::Elf_types<32>::Elf_Addr,
unsigned int got_offset,
unsigned int plt_offset,
unsigned int plt_rel_offset);
private:
// The first entry in the PLT for a shared object.
static const unsigned char first_plt_entry[plt_entry_size];
// Other entries in the PLT for a shared object.
static const unsigned char plt_entry[plt_entry_size];
};
class Target_i386_nacl : public Target_i386
{
public:
Target_i386_nacl()
: Target_i386(&i386_nacl_info)
{ }
protected:
virtual Output_data_plt_i386*
do_make_data_plt(Layout* layout,
Output_data_got_plt_i386* got_plt,
Output_data_space* got_irelative,
bool dyn)
{
if (dyn)
return new Output_data_plt_i386_nacl_dyn(layout, got_plt, got_irelative);
else
return new Output_data_plt_i386_nacl_exec(layout, got_plt, got_irelative);
}
virtual std::string
do_code_fill(section_size_type length) const;
private:
static const Target::Target_info i386_nacl_info;
};
const Target::Target_info Target_i386_nacl::i386_nacl_info =
{
32, // size
false, // is_big_endian
elfcpp::EM_386, // 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-x86-32.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_UNDEF, // large_common_shndx
0, // small_common_section_flags
0, // large_common_section_flags
NULL, // attributes_section
NULL, // attributes_vendor
"_start" // entry_symbol_name
};
#define NACLMASK 0xe0 // 32-byte alignment mask
const unsigned char
Output_data_plt_i386_nacl_exec::first_plt_entry[plt_entry_size] =
{
0xff, 0x35, // pushl contents of memory address
0, 0, 0, 0, // replaced with address of .got + 4
0x8b, 0x0d, // movl contents of address, %ecx
0, 0, 0, 0, // replaced with address of .got + 8
0x83, 0xe1, NACLMASK, // andl $NACLMASK, %ecx
0xff, 0xe1, // jmp *%ecx
0x90, 0x90, 0x90, 0x90, 0x90, 0x90, // nops
0x90, 0x90, 0x90, 0x90, 0x90, 0x90, // nops
0x90, 0x90, 0x90, 0x90, 0x90, 0x90, // nops
0x90, 0x90, 0x90, 0x90, 0x90, 0x90, // nops
0x90, 0x90, 0x90, 0x90, 0x90, 0x90, // nops
0x90, 0x90, 0x90, 0x90, 0x90, 0x90, // nops
0x90, 0x90, 0x90, 0x90, 0x90, 0x90, // nops
0x90, 0x90, 0x90, 0x90, 0x90
};
void
Output_data_plt_i386_nacl_exec::do_fill_first_plt_entry(
unsigned char* pov,
elfcpp::Elf_types<32>::Elf_Addr got_address)
{
memcpy(pov, first_plt_entry, plt_entry_size);
elfcpp::Swap_unaligned<32, false>::writeval(pov + 2, got_address + 4);
elfcpp::Swap<32, false>::writeval(pov + 8, got_address + 8);
}
// The first entry in the PLT for a shared object.
const unsigned char
Output_data_plt_i386_nacl_dyn::first_plt_entry[plt_entry_size] =
{
0xff, 0xb3, 4, 0, 0, 0, // pushl 4(%ebx)
0x8b, 0x4b, 0x08, // mov 0x8(%ebx), %ecx
0x83, 0xe1, NACLMASK, // andl $NACLMASK, %ecx
0xff, 0xe1, // jmp *%ecx
0x90, 0x90, 0x90, 0x90, 0x90, // nops
0x90, 0x90, 0x90, 0x90, 0x90, // nops
0x90, 0x90, 0x90, 0x90, 0x90, // nops
0x90, 0x90, 0x90, 0x90, 0x90, // nops
0x90, 0x90, 0x90, 0x90, 0x90, // nops
0x90, 0x90, 0x90, 0x90, 0x90, // nops
0x90, 0x90, 0x90, 0x90, 0x90, // nops
0x90, 0x90, 0x90, 0x90, 0x90, // nops
0x90, 0x90, 0x90, 0x90, 0x90, // nops
0x90, 0x90, 0x90, 0x90, 0x90 // nops
};
void
Output_data_plt_i386_nacl_dyn::do_fill_first_plt_entry(
unsigned char* pov,
elfcpp::Elf_types<32>::Elf_Addr)
{
memcpy(pov, first_plt_entry, plt_entry_size);
}
// Subsequent entries in the PLT for an executable.
const unsigned char
Output_data_plt_i386_nacl_exec::plt_entry[plt_entry_size] =
{
0x8b, 0x0d, // movl contents of address, %ecx */
0, 0, 0, 0, // replaced with address of symbol in .got
0x83, 0xe1, NACLMASK, // andl $NACLMASK, %ecx
0xff, 0xe1, // jmp *%ecx
// Pad to the next 32-byte boundary with nop instructions.
0x90,
0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90,
0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90,
// Lazy GOT entries point here (32-byte aligned).
0x68, // pushl immediate
0, 0, 0, 0, // replaced with offset into relocation table
0xe9, // jmp relative
0, 0, 0, 0, // replaced with offset to start of .plt
// Pad to the next 32-byte boundary with nop instructions.
0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90,
0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90,
0x90, 0x90
};
unsigned int
Output_data_plt_i386_nacl_exec::do_fill_plt_entry(
unsigned char* pov,
elfcpp::Elf_types<32>::Elf_Addr got_address,
unsigned int got_offset,
unsigned int plt_offset,
unsigned int plt_rel_offset)
{
memcpy(pov, plt_entry, plt_entry_size);
elfcpp::Swap_unaligned<32, false>::writeval(pov + 2,
got_address + got_offset);
elfcpp::Swap_unaligned<32, false>::writeval(pov + 33, plt_rel_offset);
elfcpp::Swap<32, false>::writeval(pov + 38, - (plt_offset + 38 + 4));
return 32;
}
// Subsequent entries in the PLT for a shared object.
const unsigned char
Output_data_plt_i386_nacl_dyn::plt_entry[plt_entry_size] =
{
0x8b, 0x8b, // movl offset(%ebx), %ecx
0, 0, 0, 0, // replaced with offset of symbol in .got
0x83, 0xe1, 0xe0, // andl $NACLMASK, %ecx
0xff, 0xe1, // jmp *%ecx
// Pad to the next 32-byte boundary with nop instructions.
0x90,
0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90,
0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90,
// Lazy GOT entries point here (32-byte aligned).
0x68, // pushl immediate
0, 0, 0, 0, // replaced with offset into relocation table.
0xe9, // jmp relative
0, 0, 0, 0, // replaced with offset to start of .plt.
// Pad to the next 32-byte boundary with nop instructions.
0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90,
0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90,
0x90, 0x90
};
unsigned int
Output_data_plt_i386_nacl_dyn::do_fill_plt_entry(
unsigned char* pov,
elfcpp::Elf_types<32>::Elf_Addr,
unsigned int got_offset,
unsigned int plt_offset,
unsigned int plt_rel_offset)
{
memcpy(pov, plt_entry, plt_entry_size);
elfcpp::Swap_unaligned<32, false>::writeval(pov + 2, got_offset);
elfcpp::Swap_unaligned<32, false>::writeval(pov + 33, plt_rel_offset);
elfcpp::Swap<32, false>::writeval(pov + 38, - (plt_offset + 38 + 4));
return 32;
}
const unsigned char
Output_data_plt_i386_nacl::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, 8, // DW_CFA_def_cfa_offset: 8.
elfcpp::DW_CFA_advance_loc + 6, // Advance 6 to __PLT__ + 6.
elfcpp::DW_CFA_def_cfa_offset, 12, // DW_CFA_def_cfa_offset: 12.
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_breg4, 4, // Push %esp + 4.
elfcpp::DW_OP_breg8, 0, // Push %eip.
elfcpp::DW_OP_const1u, 63, // Push 0x3f.
elfcpp::DW_OP_and, // & (%eip & 0x3f).
elfcpp::DW_OP_const1u, 37, // Push 0x25.
elfcpp::DW_OP_ge, // >= ((%eip & 0x3f) >= 0x25)
elfcpp::DW_OP_lit2, // Push 2.
elfcpp::DW_OP_shl, // << (((%eip & 0x3f) >= 0x25) << 2)
elfcpp::DW_OP_plus, // + ((((%eip&0x3f)>=0x25)<<2)+%esp+4
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.
std::string
Target_i386_nacl::do_code_fill(section_size_type length) const
{
return std::string(length, static_cast<char>(0x90));
}
// The selector for i386-nacl object files.
class Target_selector_i386_nacl
: public Target_selector_nacl<Target_selector_i386, Target_i386_nacl>
{
public:
Target_selector_i386_nacl()
: Target_selector_nacl<Target_selector_i386,
Target_i386_nacl>("x86-32",
"elf32-i386-nacl",
"elf_i386_nacl")
{ }
};
Target_selector_i386_nacl target_selector_i386;
} // End anonymous namespace.
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