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22f0da72ea
binutils-gdb/gold/i386.cc
Ian Lance Taylor 22f0da72ea 2010-08-03 Ian Lance Taylor <iant@google.com> 
PR 11805
	* layout.h (enum Output_section_order): Define.
	(class Layout): Update declarations.
	* layout.cc (Layout::get_output_section): Add order parameter.
	Remove is_interp, is_dynamic_linker_section, is_last_relro, and
	is_first_non_relro parameters.  Change all callers.
	(Layout::choose_output_section): Likewise.
	(Layout::add_output_section_data): Likewise.
	(Layout::make_output_section): Likewise.  Set order.
	(Layout::default_section_order): New function.
	(Layout::layout_eh_frame): Call add_output_section_to_nonload.
	* output.cc (Output_section::Output_section): Initialize order_.
	Don't initialize deleted fields.
	(Output_segment::Output_segment): Don't initialize deleted
	fields.
	(Output_segment::add_output_section_to_load): New function
	replacing add_output_section.  Change all callers to call this or
	add_output_section_to_nonload.
	(Output_segment::add_output_section_to_nonload): New function.
	(Output_segment::remove_output_section): Rewrite.
	(Output_segment::add_initial_output_data): Likewise.
	(Output_segment::has_any_data_sections): Likewise.
	(Output_segment::is_first_section_relro): Likewise.
	(Output_segment::maximum_alignment): Likewise.
	(Output_segment::has_dynamic_reloc): New function replacing
	dynamic_reloc_count.  Change all callers.
	(Output_segment::has_dynamic_reloc_list): New function replacing
	dynamic_reloc_count_list.  Change all callers.
	(Output_segment::set_section_addresses): Rewrite.
	(Output_segment::set_offset): Rewrite.
	(Output_segment::find_first_and_last_list): Remove.
	(Output_segment::set_tls_offsets): Rewrite.
	(Output_segment::first_section_load_address): Likewise.
	(Output_segment::output_section_count): Likewise.
	(Output_segment::section_with_lowest_load_address): Likewise.
	(Output_segment::write_section_headers): Likewise.
	(Output_segment::print_sections_to_map): Likewise.
	* output.h (class Output_data): Remove dynamic_reloc_count_
	field.  Add has_dynamic_reloc_ field.  Make bools into bitfields.
	(Output_data::add_dynamic_reloc): Rewrite.
	(Output_data::has_dynamic_reloc): New function.
	(Output_data::dynamic_reloc_count): Remove.
	(class Output_section): Add order_ field.  Remvoe is_relro_local_,
	is_last_relro_, is_first_non_relro_, is_interp_,
	is_dynamic_linker_section_ fields.  Add order and set_order
	functions.  Remove is_relro_local, set_is_relro_local,
	is_last_relro, set_is_last_relro, is_first_non_relro,
	set_is_first_non_relro functions, is_interp, set_is_interp,
	is_dynamic_linker_section, and set_is_dynamic_linker_section
	functions.
	(class Output_segment): Change Output_data_list from std::list to
	std:;vector.  Add output_lists_ field.  Remove output_data_ and
	output_bss_ fields.  Update declarations.
2010-08-03 14:07:13 +00:00

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// i386.cc -- i386 target support for gold.
// Copyright 2006, 2007, 2008, 2009, 2010 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 "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 "gc.h"
namespace
{
using namespace gold;
class Output_data_plt_i386;
// 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 Target_freebsd<32, false>
{
public:
typedef Output_data_reloc<elfcpp::SHT_REL, true, 32, false> Reloc_section;
Target_i386()
: Target_freebsd<32, false>(&i386_info),
got_(NULL), plt_(NULL), got_plt_(NULL), got_tlsdesc_(NULL),
global_offset_table_(NULL), rel_dyn_(NULL),
copy_relocs_(elfcpp::R_386_COPY), dynbss_(NULL),
got_mod_index_offset_(-1U), tls_base_symbol_defined_(false)
{ }
inline bool
can_check_for_function_pointers() const
{ return true; }
// Process the relocations to determine unreferenced sections for
// garbage collection.
void
gc_process_relocs(Symbol_table* symtab,
Layout* layout,
Sized_relobj<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<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<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*);
// Relocate a section during a relocatable link.
void
relocate_for_relocatable(const Relocate_info<32, false>*,
unsigned int sh_type,
const unsigned char* prelocs,
size_t reloc_count,
Output_section* output_section,
off_t offset_in_output_section,
const Relocatable_relocs*,
unsigned char* view,
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 whether SYM is call to a non-split function.
bool
do_is_call_to_non_split(const Symbol* sym, unsigned int) const;
// Adjust -fstack-split code which calls non-stack-split 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()
{
gold_assert(this->got_ != NULL);
return this->got_->data_size();
}
private:
// The class which scans relocations.
struct Scan
{
inline void
local(Symbol_table* symtab, Layout* layout, Target_i386* target,
Sized_relobj<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 void
global(Symbol_table* symtab, Layout* layout, Target_i386* target,
Sized_relobj<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<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<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);
static void
unsupported_reloc_local(Sized_relobj<32, false>*, unsigned int r_type);
static void
unsupported_reloc_global(Sized_relobj<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,
int ref_flags,
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_space*
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 a PLT entry for a global symbol.
void
make_plt_entry(Symbol_table*, Layout*, Symbol*);
// 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<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;
// Add a potential copy relocation.
void
copy_reloc(Symbol_table* symtab, Layout* layout,
Sized_relobj<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.
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_space* got_plt_;
// 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_;
// Relocs saved to avoid a COPY reloc.
Copy_relocs<elfcpp::SHT_REL, 32, false> copy_relocs_;
// Space for variables copied with a COPY reloc.
Output_data_space* dynbss_;
// 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
'\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)
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
};
// 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>();
layout->add_output_section_data(".got", elfcpp::SHT_PROGBITS,
(elfcpp::SHF_ALLOC
| elfcpp::SHF_WRITE),
this->got_, ORDER_RELRO_LAST, true);
this->got_plt_ = new Output_data_space(4, "** GOT PLT");
layout->add_output_section_data(".got.plt", elfcpp::SHT_PROGBITS,
(elfcpp::SHF_ALLOC
| elfcpp::SHF_WRITE),
this->got_plt_, ORDER_NON_RELRO_FIRST,
false);
// The first three entries are reserved.
this->got_plt_->set_current_data_size(3 * 4);
// 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 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_,
ORDER_NON_RELRO_FIRST, false);
}
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_;
}
// A class to handle the PLT data.
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*, Output_data_space*);
// Add an entry to the PLT.
void
add_entry(Symbol* gsym);
// Return the .rel.plt section data.
const Reloc_section*
rel_plt() const
{ return this->rel_; }
// Return where the TLS_DESC relocations should go.
Reloc_section*
rel_tls_desc(Layout*);
protected:
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")); }
private:
// The size of an entry in the PLT.
static const int plt_entry_size = 16;
// The first entry in the PLT for an executable.
static unsigned char exec_first_plt_entry[plt_entry_size];
// The first entry in the PLT for a shared object.
static unsigned char dyn_first_plt_entry[plt_entry_size];
// Other entries in the PLT for an executable.
static unsigned char exec_plt_entry[plt_entry_size];
// Other entries in the PLT for a shared object.
static unsigned char dyn_plt_entry[plt_entry_size];
// Set the final size.
void
set_final_data_size()
{ this->set_data_size((this->count_ + 1) * plt_entry_size); }
// Write out the PLT data.
void
do_write(Output_file*);
// 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 .got.plt section.
Output_data_space* got_plt_;
// The number of PLT entries.
unsigned int count_;
};
// 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,
Output_data_space* got_plt)
: Output_section_data(4), tls_desc_rel_(NULL), got_plt_(got_plt), count_(0)
{
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* gsym)
{
gold_assert(!gsym->has_plt_offset());
// Note that when setting the PLT offset we skip the initial
// reserved PLT entry.
gsym->set_plt_offset((this->count_ + 1) * 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);
// Every PLT entry needs a reloc.
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.
}
// 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_;
}
// The first entry in the PLT for an executable.
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
};
// The first entry in the PLT for a shared object.
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
};
// Subsequent entries in the PLT for an executable.
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
};
// Subsequent entries in the PLT for a shared object.
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
};
// 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();
const section_size_type got_size =
convert_to_section_size_type(this->got_plt_->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();
if (parameters->options().output_is_position_independent())
memcpy(pov, dyn_first_plt_entry, plt_entry_size);
else
{
memcpy(pov, exec_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);
}
pov += plt_entry_size;
unsigned char* got_pov = got_view;
memset(got_pov, 0, 12);
got_pov += 12;
const int rel_size = elfcpp::Elf_sizes<32>::rel_size;
unsigned int plt_offset = plt_entry_size;
unsigned int plt_rel_offset = 0;
unsigned int got_offset = 12;
const unsigned int count = this->count_;
for (unsigned int i = 0;
i < count;
++i,
pov += plt_entry_size,
got_pov += 4,
plt_offset += plt_entry_size,
plt_rel_offset += rel_size,
got_offset += 4)
{
// Set and adjust the PLT entry itself.
if (parameters->options().output_is_position_independent())
{
memcpy(pov, dyn_plt_entry, plt_entry_size);
elfcpp::Swap_unaligned<32, false>::writeval(pov + 2, got_offset);
}
else
{
memcpy(pov, exec_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 + plt_entry_size));
// Set the entry in the GOT.
elfcpp::Swap<32, false>::writeval(got_pov, plt_address + plt_offset + 6);
}
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 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)
{
// Create the GOT sections first.
this->got_section(symtab, layout);
this->plt_ = new Output_data_plt_i386(layout, this->got_plt_);
layout->add_output_section_data(".plt", elfcpp::SHT_PROGBITS,
(elfcpp::SHF_ALLOC
| elfcpp::SHF_EXECINSTR),
this->plt_, ORDER_PLT, false);
}
this->plt_->add_entry(gsym);
}
// 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<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();
}
}
// Report an unsupported relocation against a local symbol.
void
Target_i386::Scan::unsupported_reloc_local(Sized_relobj<32, false>* object,
unsigned int r_type)
{
gold_error(_("%s: unsupported reloc %u against local symbol"),
object->name().c_str(), r_type);
}
// Scan a relocation for a local symbol.
inline void
Target_i386::Scan::local(Symbol_table* symtab,
Layout* layout,
Target_i386* target,
Sized_relobj<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)
{
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());
if (got->add_local(object, r_sym, GOT_TYPE_STANDARD))
{
// 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 r_sym = elfcpp::elf_r_sym<32>(reloc.get_r_info());
rel_dyn->add_local_relative(
object, r_sym, elfcpp::R_386_RELATIVE, got,
object->local_got_offset(r_sym, GOT_TYPE_STANDARD));
}
}
}
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_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, 0);
}
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<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<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<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<32, false>* object,
unsigned int data_shndx,
Output_section* output_section,
const elfcpp::Rel<32, false>& reloc,
unsigned int r_type,
Symbol* 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(Symbol::ABSOLUTE_REF))
{
if (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->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.
int flags = Symbol::NON_PIC_REF;
if (gsym->is_func())
flags |= Symbol::FUNCTION_CALL;
if (gsym->needs_dynamic_reloc(flags))
{
if (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())
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);
if (gsym->is_from_dynobj()
|| gsym->is_undefined()
|| gsym->is_preemptible())
got->add_global_with_rel(gsym, GOT_TYPE_STANDARD,
rel_dyn, elfcpp::R_386_GLOB_DAT);
else
{
if (got->add_global(gsym, GOT_TYPE_STANDARD))
rel_dyn->add_global_relative(
gsym, elfcpp::R_386_RELATIVE, got,
gsym->got_offset(GOT_TYPE_STANDARD));
}
}
}
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_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<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<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);
}
}
// 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,
int ref_flags,
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;
// 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;
}
}
// Pick the value to use for symbols defined in shared objects.
Symbol_value<32> symval;
if (gsym != NULL
&& gsym->use_plt_offset(r_type == elfcpp::R_386_PC8
|| r_type == elfcpp::R_386_PC16
|| r_type == elfcpp::R_386_PC32))
{
symval.set_output_value(target->plt_section()->address()
+ gsym->plt_offset());
psymval = &symval;
}
const Sized_relobj<32, false>* object = relinfo->object;
// 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, Symbol::ABSOLUTE_REF, true,
output_section))
Relocate_functions<32, false>::rel32(view, object, psymval);
break;
case elfcpp::R_386_PC32:
{
int ref_flags = Symbol::NON_PIC_REF;
if (gsym != NULL && gsym->is_func())
ref_flags |= Symbol::FUNCTION_CALL;
if (should_apply_static_reloc(gsym, ref_flags, true, output_section))
Relocate_functions<32, false>::pcrel32(view, object, psymval, address);
}
break;
case elfcpp::R_386_16:
if (should_apply_static_reloc(gsym, Symbol::ABSOLUTE_REF, false,
output_section))
Relocate_functions<32, false>::rel16(view, object, psymval);
break;
case elfcpp::R_386_PC16:
{
int ref_flags = Symbol::NON_PIC_REF;
if (gsym != NULL && gsym->is_func())
ref_flags |= Symbol::FUNCTION_CALL;
if (should_apply_static_reloc(gsym, ref_flags, false, output_section))
Relocate_functions<32, false>::pcrel16(view, object, psymval, address);
}
break;
case elfcpp::R_386_8:
if (should_apply_static_reloc(gsym, Symbol::ABSOLUTE_REF, false,
output_section))
Relocate_functions<32, false>::rel8(view, object, psymval);
break;
case elfcpp::R_386_PC8:
{
int ref_flags = Symbol::NON_PIC_REF;
if (gsym != NULL && gsym->is_func())
ref_flags |= Symbol::FUNCTION_CALL;
if (should_apply_static_reloc(gsym, ref_flags, 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:
// 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<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)
{
gold_assert(tls_segment != NULL);
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)
{
gold_assert(tls_segment != NULL);
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)
{
gold_assert(tls_segment != NULL);
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)
{
gold_assert(tls_segment != NULL);
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)
{
gold_assert(tls_segment != NULL);
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)
{
gold_assert(tls_segment != NULL);
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)
{
gold_assert(tls_segment != NULL);
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())
{
gold_assert(tls_segment != NULL);
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())
{
gold_assert(tls_segment != NULL);
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>(
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_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<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);
}
// Relocate a section during a relocatable link.
void
Target_i386::relocate_for_relocatable(
const Relocate_info<32, false>* relinfo,
unsigned int sh_type,
const unsigned char* prelocs,
size_t reloc_count,
Output_section* output_section,
off_t offset_in_output_section,
const Relocatable_relocs* 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_for_relocatable<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_section()->address() + gsym->plt_offset();
}
// 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, '\0'));
}
// Nop sequences of various lengths.
const char nop1[1] = { 0x90 }; // nop
const char nop2[2] = { 0x66, 0x90 }; // xchg %ax %ax
const char nop3[3] = { 0x8d, 0x76, 0x00 }; // leal 0(%esi),%esi
const char nop4[4] = { 0x8d, 0x74, 0x26, 0x00}; // leal 0(%esi,1),%esi
const char nop5[5] = { 0x90, 0x8d, 0x74, 0x26, // nop
0x00 }; // leal 0(%esi,1),%esi
const char nop6[6] = { 0x8d, 0xb6, 0x00, 0x00, // leal 0L(%esi),%esi
0x00, 0x00 };
const char nop7[7] = { 0x8d, 0xb4, 0x26, 0x00, // leal 0L(%esi,1),%esi
0x00, 0x00, 0x00 };
const char nop8[8] = { 0x90, 0x8d, 0xb4, 0x26, // nop
0x00, 0x00, 0x00, 0x00 }; // leal 0L(%esi,1),%esi
const char nop9[9] = { 0x89, 0xf6, 0x8d, 0xbc, // movl %esi,%esi
0x27, 0x00, 0x00, 0x00, // leal 0L(%edi,1),%edi
0x00 };
const char nop10[10] = { 0x8d, 0x76, 0x00, 0x8d, // leal 0(%esi),%esi
0xbc, 0x27, 0x00, 0x00, // leal 0L(%edi,1),%edi
0x00, 0x00 };
const char nop11[11] = { 0x8d, 0x74, 0x26, 0x00, // leal 0(%esi,1),%esi
0x8d, 0xbc, 0x27, 0x00, // leal 0L(%edi,1),%edi
0x00, 0x00, 0x00 };
const char nop12[12] = { 0x8d, 0xb6, 0x00, 0x00, // leal 0L(%esi),%esi
0x00, 0x00, 0x8d, 0xbf, // leal 0L(%edi),%edi
0x00, 0x00, 0x00, 0x00 };
const char nop13[13] = { 0x8d, 0xb6, 0x00, 0x00, // leal 0L(%esi),%esi
0x00, 0x00, 0x8d, 0xbc, // leal 0L(%edi,1),%edi
0x27, 0x00, 0x00, 0x00,
0x00 };
const char nop14[14] = { 0x8d, 0xb4, 0x26, 0x00, // leal 0L(%esi,1),%esi
0x00, 0x00, 0x00, 0x8d, // leal 0L(%edi,1),%edi
0xbc, 0x27, 0x00, 0x00,
0x00, 0x00 };
const char nop15[15] = { 0xeb, 0x0d, 0x90, 0x90, // jmp .+15
0x90, 0x90, 0x90, 0x90, // nop,nop,nop,...
0x90, 0x90, 0x90, 0x90,
0x90, 0x90, 0x90 };
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 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 -fstack-split. The function calls non-stack-split
// 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.
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")
{ }
Target*
do_instantiate_target()
{ return new Target_i386(); }
};
Target_selector_i386 target_selector_i386;
} // End anonymous namespace.
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