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5193828376
binutils-gdb/gold/arm.cc
Doug Kwan 5193828376 2009-11-25 Doug Kwan <dougkwan@google.com> 
* arm.cc (Target_arm::Target_arm): Move method definition outside of
	class definition.  Add code to handle --target1-rel, --target1-abs
	and --target2= options.
	(Target_arm::get_reloc_reloc_type): Change method to be non-static
	and const.
	(Target_arm::target1_is_rel_, Target_arm::target2_reloc_): New data
	member declaration.
	(Target_arm::Scan::local, Target_arm::Scan::global,
	Target_arm::Relocate::relocate,
	Target_arm::Relocatable_size_for_reloc::get_size_for_reloc): Adjust
	call to Target_arm::get_real_reloc_type.
	(Target_arm::get_real_reloc_type): Use command line options to
	determine real types of R_ARM_TARGET1 and R_ARM_TARGET2.
	* options.h (--target1-rel, --target1-abs, --target2): New ARM-only
	options.
2009-11-25 04:11:56 +00:00

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// arm.cc -- arm target support for gold.
// Copyright 2009 Free Software Foundation, Inc.
// Written by Doug Kwan <dougkwan@google.com> based on the i386 code
// by Ian Lance Taylor <iant@google.com>.
// This file also contains borrowed and adapted code from
// bfd/elf32-arm.c.
// 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 <limits>
#include <cstdio>
#include <string>
#include <algorithm>
#include "elfcpp.h"
#include "parameters.h"
#include "reloc.h"
#include "arm.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 "defstd.h"
#include "gc.h"
namespace
{
using namespace gold;
template<bool big_endian>
class Output_data_plt_arm;
template<bool big_endian>
class Stub_table;
template<bool big_endian>
class Arm_input_section;
template<bool big_endian>
class Arm_output_section;
template<bool big_endian>
class Arm_relobj;
template<bool big_endian>
class Target_arm;
// For convenience.
typedef elfcpp::Elf_types<32>::Elf_Addr Arm_address;
// Maximum branch offsets for ARM, THUMB and THUMB2.
const int32_t ARM_MAX_FWD_BRANCH_OFFSET = ((((1 << 23) - 1) << 2) + 8);
const int32_t ARM_MAX_BWD_BRANCH_OFFSET = ((-((1 << 23) << 2)) + 8);
const int32_t THM_MAX_FWD_BRANCH_OFFSET = ((1 << 22) -2 + 4);
const int32_t THM_MAX_BWD_BRANCH_OFFSET = (-(1 << 22) + 4);
const int32_t THM2_MAX_FWD_BRANCH_OFFSET = (((1 << 24) - 2) + 4);
const int32_t THM2_MAX_BWD_BRANCH_OFFSET = (-(1 << 24) + 4);
// The arm target class.
//
// This is a very simple port of gold for ARM-EABI. It is intended for
// supporting Android only for the time being. Only these relocation types
// are supported.
//
// R_ARM_NONE
// R_ARM_ABS32
// R_ARM_ABS32_NOI
// R_ARM_ABS16
// R_ARM_ABS12
// R_ARM_ABS8
// R_ARM_THM_ABS5
// R_ARM_BASE_ABS
// R_ARM_REL32
// R_ARM_THM_CALL
// R_ARM_COPY
// R_ARM_GLOB_DAT
// R_ARM_BASE_PREL
// R_ARM_JUMP_SLOT
// R_ARM_RELATIVE
// R_ARM_GOTOFF32
// R_ARM_GOT_BREL
// R_ARM_GOT_PREL
// R_ARM_PLT32
// R_ARM_CALL
// R_ARM_JUMP24
// R_ARM_TARGET1
// R_ARM_PREL31
// R_ARM_ABS8
// R_ARM_MOVW_ABS_NC
// R_ARM_MOVT_ABS
// R_ARM_THM_MOVW_ABS_NC
// R_ARM_THM_MOVT_ABS
// R_ARM_MOVW_PREL_NC
// R_ARM_MOVT_PREL
// R_ARM_THM_MOVW_PREL_NC
// R_ARM_THM_MOVT_PREL
//
// TODOs:
// - Generate various branch stubs.
// - Support interworking.
// - Define section symbols __exidx_start and __exidx_stop.
// - Support more relocation types as needed.
// - Make PLTs more flexible for different architecture features like
// Thumb-2 and BE8.
// There are probably a lot more.
// Instruction template class. This class is similar to the insn_sequence
// struct in bfd/elf32-arm.c.
class Insn_template
{
public:
// Types of instruction templates.
enum Type
{
THUMB16_TYPE = 1,
THUMB32_TYPE,
ARM_TYPE,
DATA_TYPE
};
// Factory methods to create instrunction templates in different formats.
static const Insn_template
thumb16_insn(uint32_t data)
{ return Insn_template(data, THUMB16_TYPE, elfcpp::R_ARM_NONE, 0); }
// A bit of a hack. A Thumb conditional branch, in which the proper
// condition is inserted when we build the stub.
static const Insn_template
thumb16_bcond_insn(uint32_t data)
{ return Insn_template(data, THUMB16_TYPE, elfcpp::R_ARM_NONE, 1); }
static const Insn_template
thumb32_insn(uint32_t data)
{ return Insn_template(data, THUMB32_TYPE, elfcpp::R_ARM_NONE, 0); }
static const Insn_template
thumb32_b_insn(uint32_t data, int reloc_addend)
{
return Insn_template(data, THUMB32_TYPE, elfcpp::R_ARM_THM_JUMP24,
reloc_addend);
}
static const Insn_template
arm_insn(uint32_t data)
{ return Insn_template(data, ARM_TYPE, elfcpp::R_ARM_NONE, 0); }
static const Insn_template
arm_rel_insn(unsigned data, int reloc_addend)
{ return Insn_template(data, ARM_TYPE, elfcpp::R_ARM_JUMP24, reloc_addend); }
static const Insn_template
data_word(unsigned data, unsigned int r_type, int reloc_addend)
{ return Insn_template(data, DATA_TYPE, r_type, reloc_addend); }
// Accessors. This class is used for read-only objects so no modifiers
// are provided.
uint32_t
data() const
{ return this->data_; }
// Return the instruction sequence type of this.
Type
type() const
{ return this->type_; }
// Return the ARM relocation type of this.
unsigned int
r_type() const
{ return this->r_type_; }
int32_t
reloc_addend() const
{ return this->reloc_addend_; }
// Return size of instrunction template in bytes.
size_t
size() const;
// Return byte-alignment of instrunction template.
unsigned
alignment() const;
private:
// We make the constructor private to ensure that only the factory
// methods are used.
inline
Insn_template(unsigned data, Type type, unsigned int r_type, int reloc_addend)
: data_(data), type_(type), r_type_(r_type), reloc_addend_(reloc_addend)
{ }
// Instruction specific data. This is used to store information like
// some of the instruction bits.
uint32_t data_;
// Instruction template type.
Type type_;
// Relocation type if there is a relocation or R_ARM_NONE otherwise.
unsigned int r_type_;
// Relocation addend.
int32_t reloc_addend_;
};
// Macro for generating code to stub types. One entry per long/short
// branch stub
#define DEF_STUBS \
DEF_STUB(long_branch_any_any) \
DEF_STUB(long_branch_v4t_arm_thumb) \
DEF_STUB(long_branch_thumb_only) \
DEF_STUB(long_branch_v4t_thumb_thumb) \
DEF_STUB(long_branch_v4t_thumb_arm) \
DEF_STUB(short_branch_v4t_thumb_arm) \
DEF_STUB(long_branch_any_arm_pic) \
DEF_STUB(long_branch_any_thumb_pic) \
DEF_STUB(long_branch_v4t_thumb_thumb_pic) \
DEF_STUB(long_branch_v4t_arm_thumb_pic) \
DEF_STUB(long_branch_v4t_thumb_arm_pic) \
DEF_STUB(long_branch_thumb_only_pic) \
DEF_STUB(a8_veneer_b_cond) \
DEF_STUB(a8_veneer_b) \
DEF_STUB(a8_veneer_bl) \
DEF_STUB(a8_veneer_blx)
// Stub types.
#define DEF_STUB(x) arm_stub_##x,
typedef enum
{
arm_stub_none,
DEF_STUBS
// First reloc stub type.
arm_stub_reloc_first = arm_stub_long_branch_any_any,
// Last reloc stub type.
arm_stub_reloc_last = arm_stub_long_branch_thumb_only_pic,
// First Cortex-A8 stub type.
arm_stub_cortex_a8_first = arm_stub_a8_veneer_b_cond,
// Last Cortex-A8 stub type.
arm_stub_cortex_a8_last = arm_stub_a8_veneer_blx,
// Last stub type.
arm_stub_type_last = arm_stub_a8_veneer_blx
} Stub_type;
#undef DEF_STUB
// Stub template class. Templates are meant to be read-only objects.
// A stub template for a stub type contains all read-only attributes
// common to all stubs of the same type.
class Stub_template
{
public:
Stub_template(Stub_type, const Insn_template*, size_t);
~Stub_template()
{ }
// Return stub type.
Stub_type
type() const
{ return this->type_; }
// Return an array of instruction templates.
const Insn_template*
insns() const
{ return this->insns_; }
// Return size of template in number of instructions.
size_t
insn_count() const
{ return this->insn_count_; }
// Return size of template in bytes.
size_t
size() const
{ return this->size_; }
// Return alignment of the stub template.
unsigned
alignment() const
{ return this->alignment_; }
// Return whether entry point is in thumb mode.
bool
entry_in_thumb_mode() const
{ return this->entry_in_thumb_mode_; }
// Return number of relocations in this template.
size_t
reloc_count() const
{ return this->relocs_.size(); }
// Return index of the I-th instruction with relocation.
size_t
reloc_insn_index(size_t i) const
{
gold_assert(i < this->relocs_.size());
return this->relocs_[i].first;
}
// Return the offset of the I-th instruction with relocation from the
// beginning of the stub.
section_size_type
reloc_offset(size_t i) const
{
gold_assert(i < this->relocs_.size());
return this->relocs_[i].second;
}
private:
// This contains information about an instruction template with a relocation
// and its offset from start of stub.
typedef std::pair<size_t, section_size_type> Reloc;
// A Stub_template may not be copied. We want to share templates as much
// as possible.
Stub_template(const Stub_template&);
Stub_template& operator=(const Stub_template&);
// Stub type.
Stub_type type_;
// Points to an array of Insn_templates.
const Insn_template* insns_;
// Number of Insn_templates in insns_[].
size_t insn_count_;
// Size of templated instructions in bytes.
size_t size_;
// Alignment of templated instructions.
unsigned alignment_;
// Flag to indicate if entry is in thumb mode.
bool entry_in_thumb_mode_;
// A table of reloc instruction indices and offsets. We can find these by
// looking at the instruction templates but we pre-compute and then stash
// them here for speed.
std::vector<Reloc> relocs_;
};
//
// A class for code stubs. This is a base class for different type of
// stubs used in the ARM target.
//
class Stub
{
private:
static const section_offset_type invalid_offset =
static_cast<section_offset_type>(-1);
public:
Stub(const Stub_template* stub_template)
: stub_template_(stub_template), offset_(invalid_offset)
{ }
virtual
~Stub()
{ }
// Return the stub template.
const Stub_template*
stub_template() const
{ return this->stub_template_; }
// Return offset of code stub from beginning of its containing stub table.
section_offset_type
offset() const
{
gold_assert(this->offset_ != invalid_offset);
return this->offset_;
}
// Set offset of code stub from beginning of its containing stub table.
void
set_offset(section_offset_type offset)
{ this->offset_ = offset; }
// Return the relocation target address of the i-th relocation in the
// stub. This must be defined in a child class.
Arm_address
reloc_target(size_t i)
{ return this->do_reloc_target(i); }
// Write a stub at output VIEW. BIG_ENDIAN select how a stub is written.
void
write(unsigned char* view, section_size_type view_size, bool big_endian)
{ this->do_write(view, view_size, big_endian); }
protected:
// This must be defined in the child class.
virtual Arm_address
do_reloc_target(size_t) = 0;
// This must be defined in the child class.
virtual void
do_write(unsigned char*, section_size_type, bool) = 0;
private:
// Its template.
const Stub_template* stub_template_;
// Offset within the section of containing this stub.
section_offset_type offset_;
};
// Reloc stub class. These are stubs we use to fix up relocation because
// of limited branch ranges.
class Reloc_stub : public Stub
{
public:
static const unsigned int invalid_index = static_cast<unsigned int>(-1);
// We assume we never jump to this address.
static const Arm_address invalid_address = static_cast<Arm_address>(-1);
// Return destination address.
Arm_address
destination_address() const
{
gold_assert(this->destination_address_ != this->invalid_address);
return this->destination_address_;
}
// Set destination address.
void
set_destination_address(Arm_address address)
{
gold_assert(address != this->invalid_address);
this->destination_address_ = address;
}
// Reset destination address.
void
reset_destination_address()
{ this->destination_address_ = this->invalid_address; }
// Determine stub type for a branch of a relocation of R_TYPE going
// from BRANCH_ADDRESS to BRANCH_TARGET. If TARGET_IS_THUMB is set,
// the branch target is a thumb instruction. TARGET is used for look
// up ARM-specific linker settings.
static Stub_type
stub_type_for_reloc(unsigned int r_type, Arm_address branch_address,
Arm_address branch_target, bool target_is_thumb);
// Reloc_stub key. A key is logically a triplet of a stub type, a symbol
// and an addend. Since we treat global and local symbol differently, we
// use a Symbol object for a global symbol and a object-index pair for
// a local symbol.
class Key
{
public:
// If SYMBOL is not null, this is a global symbol, we ignore RELOBJ and
// R_SYM. Otherwise, this is a local symbol and RELOBJ must non-NULL
// and R_SYM must not be invalid_index.
Key(Stub_type stub_type, const Symbol* symbol, const Relobj* relobj,
unsigned int r_sym, int32_t addend)
: stub_type_(stub_type), addend_(addend)
{
if (symbol != NULL)
{
this->r_sym_ = Reloc_stub::invalid_index;
this->u_.symbol = symbol;
}
else
{
gold_assert(relobj != NULL && r_sym != invalid_index);
this->r_sym_ = r_sym;
this->u_.relobj = relobj;
}
}
~Key()
{ }
// Accessors: Keys are meant to be read-only object so no modifiers are
// provided.
// Return stub type.
Stub_type
stub_type() const
{ return this->stub_type_; }
// Return the local symbol index or invalid_index.
unsigned int
r_sym() const
{ return this->r_sym_; }
// Return the symbol if there is one.
const Symbol*
symbol() const
{ return this->r_sym_ == invalid_index ? this->u_.symbol : NULL; }
// Return the relobj if there is one.
const Relobj*
relobj() const
{ return this->r_sym_ != invalid_index ? this->u_.relobj : NULL; }
// Whether this equals to another key k.
bool
eq(const Key& k) const
{
return ((this->stub_type_ == k.stub_type_)
&& (this->r_sym_ == k.r_sym_)
&& ((this->r_sym_ != Reloc_stub::invalid_index)
? (this->u_.relobj == k.u_.relobj)
: (this->u_.symbol == k.u_.symbol))
&& (this->addend_ == k.addend_));
}
// Return a hash value.
size_t
hash_value() const
{
return (this->stub_type_
^ this->r_sym_
^ gold::string_hash<char>(
(this->r_sym_ != Reloc_stub::invalid_index)
? this->u_.relobj->name().c_str()
: this->u_.symbol->name())
^ this->addend_);
}
// Functors for STL associative containers.
struct hash
{
size_t
operator()(const Key& k) const
{ return k.hash_value(); }
};
struct equal_to
{
bool
operator()(const Key& k1, const Key& k2) const
{ return k1.eq(k2); }
};
// Name of key. This is mainly for debugging.
std::string
name() const;
private:
// Stub type.
Stub_type stub_type_;
// If this is a local symbol, this is the index in the defining object.
// Otherwise, it is invalid_index for a global symbol.
unsigned int r_sym_;
// If r_sym_ is invalid index. This points to a global symbol.
// Otherwise, this points a relobj. We used the unsized and target
// independent Symbol and Relobj classes instead of Sized_symbol<32> and
// Arm_relobj. This is done to avoid making the stub class a template
// as most of the stub machinery is endianity-neutral. However, it
// may require a bit of casting done by users of this class.
union
{
const Symbol* symbol;
const Relobj* relobj;
} u_;
// Addend associated with a reloc.
int32_t addend_;
};
protected:
// Reloc_stubs are created via a stub factory. So these are protected.
Reloc_stub(const Stub_template* stub_template)
: Stub(stub_template), destination_address_(invalid_address)
{ }
~Reloc_stub()
{ }
friend class Stub_factory;
private:
// Return the relocation target address of the i-th relocation in the
// stub.
Arm_address
do_reloc_target(size_t i)
{
// All reloc stub have only one relocation.
gold_assert(i == 0);
return this->destination_address_;
}
// A template to implement do_write below.
template<bool big_endian>
void inline
do_fixed_endian_write(unsigned char*, section_size_type);
// Write a stub.
void
do_write(unsigned char* view, section_size_type view_size, bool big_endian);
// Address of destination.
Arm_address destination_address_;
};
// Stub factory class.
class Stub_factory
{
public:
// Return the unique instance of this class.
static const Stub_factory&
get_instance()
{
static Stub_factory singleton;
return singleton;
}
// Make a relocation stub.
Reloc_stub*
make_reloc_stub(Stub_type stub_type) const
{
gold_assert(stub_type >= arm_stub_reloc_first
&& stub_type <= arm_stub_reloc_last);
return new Reloc_stub(this->stub_templates_[stub_type]);
}
private:
// Constructor and destructor are protected since we only return a single
// instance created in Stub_factory::get_instance().
Stub_factory();
// A Stub_factory may not be copied since it is a singleton.
Stub_factory(const Stub_factory&);
Stub_factory& operator=(Stub_factory&);
// Stub templates. These are initialized in the constructor.
const Stub_template* stub_templates_[arm_stub_type_last+1];
};
// A class to hold stubs for the ARM target.
template<bool big_endian>
class Stub_table : public Output_data
{
public:
Stub_table(Arm_input_section<big_endian>* owner)
: Output_data(), addralign_(1), owner_(owner), has_been_changed_(false),
reloc_stubs_()
{ }
~Stub_table()
{ }
// Owner of this stub table.
Arm_input_section<big_endian>*
owner() const
{ return this->owner_; }
// Whether this stub table is empty.
bool
empty() const
{ return this->reloc_stubs_.empty(); }
// Whether this has been changed.
bool
has_been_changed() const
{ return this->has_been_changed_; }
// Set the has-been-changed flag.
void
set_has_been_changed(bool value)
{ this->has_been_changed_ = value; }
// Return the current data size.
off_t
current_data_size() const
{ return this->current_data_size_for_child(); }
// Add a STUB with using KEY. Caller is reponsible for avoid adding
// if already a STUB with the same key has been added.
void
add_reloc_stub(Reloc_stub* stub, const Reloc_stub::Key& key);
// Look up a relocation stub using KEY. Return NULL if there is none.
Reloc_stub*
find_reloc_stub(const Reloc_stub::Key& key) const
{
typename Reloc_stub_map::const_iterator p = this->reloc_stubs_.find(key);
return (p != this->reloc_stubs_.end()) ? p->second : NULL;
}
// Relocate stubs in this stub table.
void
relocate_stubs(const Relocate_info<32, big_endian>*,
Target_arm<big_endian>*, Output_section*,
unsigned char*, Arm_address, section_size_type);
protected:
// Write out section contents.
void
do_write(Output_file*);
// Return the required alignment.
uint64_t
do_addralign() const
{ return this->addralign_; }
// Finalize data size.
void
set_final_data_size()
{ this->set_data_size(this->current_data_size_for_child()); }
// Reset address and file offset.
void
do_reset_address_and_file_offset();
private:
// Unordered map of stubs.
typedef
Unordered_map<Reloc_stub::Key, Reloc_stub*, Reloc_stub::Key::hash,
Reloc_stub::Key::equal_to>
Reloc_stub_map;
// Address alignment
uint64_t addralign_;
// Owner of this stub table.
Arm_input_section<big_endian>* owner_;
// This is set to true during relaxiong if the size of the stub table
// has been changed.
bool has_been_changed_;
// The relocation stubs.
Reloc_stub_map reloc_stubs_;
};
// A class to wrap an ordinary input section containing executable code.
template<bool big_endian>
class Arm_input_section : public Output_relaxed_input_section
{
public:
Arm_input_section(Relobj* relobj, unsigned int shndx)
: Output_relaxed_input_section(relobj, shndx, 1),
original_addralign_(1), original_size_(0), stub_table_(NULL)
{ }
~Arm_input_section()
{ }
// Initialize.
void
init();
// Whether this is a stub table owner.
bool
is_stub_table_owner() const
{ return this->stub_table_ != NULL && this->stub_table_->owner() == this; }
// Return the stub table.
Stub_table<big_endian>*
stub_table() const
{ return this->stub_table_; }
// Set the stub_table.
void
set_stub_table(Stub_table<big_endian>* stub_table)
{ this->stub_table_ = stub_table; }
// Downcast a base pointer to an Arm_input_section pointer. This is
// not type-safe but we only use Arm_input_section not the base class.
static Arm_input_section<big_endian>*
as_arm_input_section(Output_relaxed_input_section* poris)
{ return static_cast<Arm_input_section<big_endian>*>(poris); }
protected:
// Write data to output file.
void
do_write(Output_file*);
// Return required alignment of this.
uint64_t
do_addralign() const
{
if (this->is_stub_table_owner())
return std::max(this->stub_table_->addralign(),
this->original_addralign_);
else
return this->original_addralign_;
}
// Finalize data size.
void
set_final_data_size();
// Reset address and file offset.
void
do_reset_address_and_file_offset();
// Output offset.
bool
do_output_offset(const Relobj* object, unsigned int shndx,
section_offset_type offset,
section_offset_type* poutput) const
{
if ((object == this->relobj())
&& (shndx == this->shndx())
&& (offset >= 0)
&& (convert_types<uint64_t, section_offset_type>(offset)
<= this->original_size_))
{
*poutput = offset;
return true;
}
else
return false;
}
private:
// Copying is not allowed.
Arm_input_section(const Arm_input_section&);
Arm_input_section& operator=(const Arm_input_section&);
// Address alignment of the original input section.
uint64_t original_addralign_;
// Section size of the original input section.
uint64_t original_size_;
// Stub table.
Stub_table<big_endian>* stub_table_;
};
// Arm output section class. This is defined mainly to add a number of
// stub generation methods.
template<bool big_endian>
class Arm_output_section : public Output_section
{
public:
Arm_output_section(const char* name, elfcpp::Elf_Word type,
elfcpp::Elf_Xword flags)
: Output_section(name, type, flags)
{ }
~Arm_output_section()
{ }
// Group input sections for stub generation.
void
group_sections(section_size_type, bool, Target_arm<big_endian>*);
// Downcast a base pointer to an Arm_output_section pointer. This is
// not type-safe but we only use Arm_output_section not the base class.
static Arm_output_section<big_endian>*
as_arm_output_section(Output_section* os)
{ return static_cast<Arm_output_section<big_endian>*>(os); }
private:
// For convenience.
typedef Output_section::Input_section Input_section;
typedef Output_section::Input_section_list Input_section_list;
// Create a stub group.
void create_stub_group(Input_section_list::const_iterator,
Input_section_list::const_iterator,
Input_section_list::const_iterator,
Target_arm<big_endian>*,
std::vector<Output_relaxed_input_section*>*);
};
// Arm_relobj class.
template<bool big_endian>
class Arm_relobj : public Sized_relobj<32, big_endian>
{
public:
static const Arm_address invalid_address = static_cast<Arm_address>(-1);
Arm_relobj(const std::string& name, Input_file* input_file, off_t offset,
const typename elfcpp::Ehdr<32, big_endian>& ehdr)
: Sized_relobj<32, big_endian>(name, input_file, offset, ehdr),
stub_tables_(), local_symbol_is_thumb_function_()
{ }
~Arm_relobj()
{ }
// Return the stub table of the SHNDX-th section if there is one.
Stub_table<big_endian>*
stub_table(unsigned int shndx) const
{
gold_assert(shndx < this->stub_tables_.size());
return this->stub_tables_[shndx];
}
// Set STUB_TABLE to be the stub_table of the SHNDX-th section.
void
set_stub_table(unsigned int shndx, Stub_table<big_endian>* stub_table)
{
gold_assert(shndx < this->stub_tables_.size());
this->stub_tables_[shndx] = stub_table;
}
// Whether a local symbol is a THUMB function. R_SYM is the symbol table
// index. This is only valid after do_count_local_symbol is called.
bool
local_symbol_is_thumb_function(unsigned int r_sym) const
{
gold_assert(r_sym < this->local_symbol_is_thumb_function_.size());
return this->local_symbol_is_thumb_function_[r_sym];
}
// Scan all relocation sections for stub generation.
void
scan_sections_for_stubs(Target_arm<big_endian>*, const Symbol_table*,
const Layout*);
// Convert regular input section with index SHNDX to a relaxed section.
void
convert_input_section_to_relaxed_section(unsigned shndx)
{
// The stubs have relocations and we need to process them after writing
// out the stubs. So relocation now must follow section write.
this->invalidate_section_offset(shndx);
this->set_relocs_must_follow_section_writes();
}
// Downcast a base pointer to an Arm_relobj pointer. This is
// not type-safe but we only use Arm_relobj not the base class.
static Arm_relobj<big_endian>*
as_arm_relobj(Relobj* relobj)
{ return static_cast<Arm_relobj<big_endian>*>(relobj); }
// Processor-specific flags in ELF file header. This is valid only after
// reading symbols.
elfcpp::Elf_Word
processor_specific_flags() const
{ return this->processor_specific_flags_; }
protected:
// Post constructor setup.
void
do_setup()
{
// Call parent's setup method.
Sized_relobj<32, big_endian>::do_setup();
// Initialize look-up tables.
Stub_table_list empty_stub_table_list(this->shnum(), NULL);
this->stub_tables_.swap(empty_stub_table_list);
}
// Count the local symbols.
void
do_count_local_symbols(Stringpool_template<char>*,
Stringpool_template<char>*);
void
do_relocate_sections(const Symbol_table* symtab, const Layout* layout,
const unsigned char* pshdrs,
typename Sized_relobj<32, big_endian>::Views* pivews);
// Read the symbol information.
void
do_read_symbols(Read_symbols_data* sd);
private:
// List of stub tables.
typedef std::vector<Stub_table<big_endian>*> Stub_table_list;
Stub_table_list stub_tables_;
// Bit vector to tell if a local symbol is a thumb function or not.
// This is only valid after do_count_local_symbol is called.
std::vector<bool> local_symbol_is_thumb_function_;
// processor-specific flags in ELF file header.
elfcpp::Elf_Word processor_specific_flags_;
};
// Arm_dynobj class.
template<bool big_endian>
class Arm_dynobj : public Sized_dynobj<32, big_endian>
{
public:
Arm_dynobj(const std::string& name, Input_file* input_file, off_t offset,
const elfcpp::Ehdr<32, big_endian>& ehdr)
: Sized_dynobj<32, big_endian>(name, input_file, offset, ehdr),
processor_specific_flags_(0)
{ }
~Arm_dynobj()
{ }
// Downcast a base pointer to an Arm_relobj pointer. This is
// not type-safe but we only use Arm_relobj not the base class.
static Arm_dynobj<big_endian>*
as_arm_dynobj(Dynobj* dynobj)
{ return static_cast<Arm_dynobj<big_endian>*>(dynobj); }
// Processor-specific flags in ELF file header. This is valid only after
// reading symbols.
elfcpp::Elf_Word
processor_specific_flags() const
{ return this->processor_specific_flags_; }
protected:
// Read the symbol information.
void
do_read_symbols(Read_symbols_data* sd);
private:
// processor-specific flags in ELF file header.
elfcpp::Elf_Word processor_specific_flags_;
};
// Functor to read reloc addends during stub generation.
template<int sh_type, bool big_endian>
struct Stub_addend_reader
{
// Return the addend for a relocation of a particular type. Depending
// on whether this is a REL or RELA relocation, read the addend from a
// view or from a Reloc object.
elfcpp::Elf_types<32>::Elf_Swxword
operator()(
unsigned int /* r_type */,
const unsigned char* /* view */,
const typename Reloc_types<sh_type,
32, big_endian>::Reloc& /* reloc */) const;
};
// Specialized Stub_addend_reader for SHT_REL type relocation sections.
template<bool big_endian>
struct Stub_addend_reader<elfcpp::SHT_REL, big_endian>
{
elfcpp::Elf_types<32>::Elf_Swxword
operator()(
unsigned int,
const unsigned char*,
const typename Reloc_types<elfcpp::SHT_REL, 32, big_endian>::Reloc&) const;
};
// Specialized Stub_addend_reader for RELA type relocation sections.
// We currently do not handle RELA type relocation sections but it is trivial
// to implement the addend reader. This is provided for completeness and to
// make it easier to add support for RELA relocation sections in the future.
template<bool big_endian>
struct Stub_addend_reader<elfcpp::SHT_RELA, big_endian>
{
elfcpp::Elf_types<32>::Elf_Swxword
operator()(
unsigned int,
const unsigned char*,
const typename Reloc_types<elfcpp::SHT_RELA, 32,
big_endian>::Reloc& reloc) const
{ return reloc.get_r_addend(); }
};
// Utilities for manipulating integers of up to 32-bits
namespace utils
{
// Sign extend an n-bit unsigned integer stored in an uint32_t into
// an int32_t. NO_BITS must be between 1 to 32.
template<int no_bits>
static inline int32_t
sign_extend(uint32_t bits)
{
gold_assert(no_bits >= 0 && no_bits <= 32);
if (no_bits == 32)
return static_cast<int32_t>(bits);
uint32_t mask = (~((uint32_t) 0)) >> (32 - no_bits);
bits &= mask;
uint32_t top_bit = 1U << (no_bits - 1);
int32_t as_signed = static_cast<int32_t>(bits);
return (bits & top_bit) ? as_signed + (-top_bit * 2) : as_signed;
}
// Detects overflow of an NO_BITS integer stored in a uint32_t.
template<int no_bits>
static inline bool
has_overflow(uint32_t bits)
{
gold_assert(no_bits >= 0 && no_bits <= 32);
if (no_bits == 32)
return false;
int32_t max = (1 << (no_bits - 1)) - 1;
int32_t min = -(1 << (no_bits - 1));
int32_t as_signed = static_cast<int32_t>(bits);
return as_signed > max || as_signed < min;
}
// Detects overflow of an NO_BITS integer stored in a uint32_t when it
// fits in the given number of bits as either a signed or unsigned value.
// For example, has_signed_unsigned_overflow<8> would check
// -128 <= bits <= 255
template<int no_bits>
static inline bool
has_signed_unsigned_overflow(uint32_t bits)
{
gold_assert(no_bits >= 2 && no_bits <= 32);
if (no_bits == 32)
return false;
int32_t max = static_cast<int32_t>((1U << no_bits) - 1);
int32_t min = -(1 << (no_bits - 1));
int32_t as_signed = static_cast<int32_t>(bits);
return as_signed > max || as_signed < min;
}
// Select bits from A and B using bits in MASK. For each n in [0..31],
// the n-th bit in the result is chosen from the n-th bits of A and B.
// A zero selects A and a one selects B.
static inline uint32_t
bit_select(uint32_t a, uint32_t b, uint32_t mask)
{ return (a & ~mask) | (b & mask); }
};
template<bool big_endian>
class Target_arm : public Sized_target<32, big_endian>
{
public:
typedef Output_data_reloc<elfcpp::SHT_REL, true, 32, big_endian>
Reloc_section;
// When were are relocating a stub, we pass this as the relocation number.
static const size_t fake_relnum_for_stubs = static_cast<size_t>(-1);
Target_arm()
: Sized_target<32, big_endian>(&arm_info),
got_(NULL), plt_(NULL), got_plt_(NULL), rel_dyn_(NULL),
copy_relocs_(elfcpp::R_ARM_COPY), dynbss_(NULL), stub_tables_(),
stub_factory_(Stub_factory::get_instance()),
may_use_blx_(true), should_force_pic_veneer_(false),
arm_input_section_map_()
{ }
// Whether we can use BLX.
bool
may_use_blx() const
{ return this->may_use_blx_; }
// Set use-BLX flag.
void
set_may_use_blx(bool value)
{ this->may_use_blx_ = value; }
// Whether we force PCI branch veneers.
bool
should_force_pic_veneer() const
{ return this->should_force_pic_veneer_; }
// Set PIC veneer flag.
void
set_should_force_pic_veneer(bool value)
{ this->should_force_pic_veneer_ = value; }
// Whether we use THUMB-2 instructions.
bool
using_thumb2() const
{
// FIXME: This should not hard-coded.
return false;
}
// Whether we use THUMB/THUMB-2 instructions only.
bool
using_thumb_only() const
{
// FIXME: This should not hard-coded.
return false;
}
// Whether we have an NOP instruction. If not, use mov r0, r0 instead.
bool
may_use_arm_nop() const
{
// FIXME: This should not hard-coded.
return false;
}
// Whether we have THUMB-2 NOP.W instruction.
bool
may_use_thumb2_nop() const
{
// FIXME: This should not hard-coded.
return false;
}
// Process the relocations to determine unreferenced sections for
// garbage collection.
void
gc_process_relocs(Symbol_table* symtab,
Layout* layout,
Sized_relobj<32, big_endian>* object,
unsigned int data_shndx,
unsigned int sh_type,
const unsigned char* prelocs,
size_t reloc_count,
Output_section* output_section,
bool needs_special_offset_handling,
size_t local_symbol_count,
const unsigned char* plocal_symbols);
// Scan the relocations to look for symbol adjustments.
void
scan_relocs(Symbol_table* symtab,
Layout* layout,
Sized_relobj<32, big_endian>* object,
unsigned int data_shndx,
unsigned int sh_type,
const unsigned char* prelocs,
size_t reloc_count,
Output_section* output_section,
bool needs_special_offset_handling,
size_t local_symbol_count,
const unsigned char* plocal_symbols);
// Finalize the sections.
void
do_finalize_sections(Layout*, const Input_objects*);
// Return the value to use for a dynamic symbol which requires special
// treatment.
uint64_t
do_dynsym_value(const Symbol*) const;
// Relocate a section.
void
relocate_section(const Relocate_info<32, big_endian>*,
unsigned int sh_type,
const unsigned char* prelocs,
size_t reloc_count,
Output_section* output_section,
bool needs_special_offset_handling,
unsigned char* view,
Arm_address 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, big_endian>* object,
unsigned int data_shndx,
unsigned int sh_type,
const unsigned char* prelocs,
size_t reloc_count,
Output_section* output_section,
bool needs_special_offset_handling,
size_t local_symbol_count,
const unsigned char* plocal_symbols,
Relocatable_relocs*);
// Relocate a section during a relocatable link.
void
relocate_for_relocatable(const Relocate_info<32, big_endian>*,
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,
Arm_address view_address,
section_size_type view_size,
unsigned char* reloc_view,
section_size_type reloc_view_size);
// Return whether SYM is defined by the ABI.
bool
do_is_defined_by_abi(Symbol* sym) const
{ return strcmp(sym->name(), "__tls_get_addr") == 0; }
// Return the size of the GOT section.
section_size_type
got_size()
{
gold_assert(this->got_ != NULL);
return this->got_->data_size();
}
// Map platform-specific reloc types
static unsigned int
get_real_reloc_type (unsigned int r_type);
//
// Methods to support stub-generations.
//
// Return the stub factory
const Stub_factory&
stub_factory() const
{ return this->stub_factory_; }
// Make a new Arm_input_section object.
Arm_input_section<big_endian>*
new_arm_input_section(Relobj*, unsigned int);
// Find the Arm_input_section object corresponding to the SHNDX-th input
// section of RELOBJ.
Arm_input_section<big_endian>*
find_arm_input_section(Relobj* relobj, unsigned int shndx) const;
// Make a new Stub_table
Stub_table<big_endian>*
new_stub_table(Arm_input_section<big_endian>*);
// Scan a section for stub generation.
void
scan_section_for_stubs(const Relocate_info<32, big_endian>*, unsigned int,
const unsigned char*, size_t, Output_section*,
bool, const unsigned char*, Arm_address,
section_size_type);
// Relocate a stub.
void
relocate_stub(Reloc_stub*, const Relocate_info<32, big_endian>*,
Output_section*, unsigned char*, Arm_address,
section_size_type);
// Get the default ARM target.
static Target_arm<big_endian>*
default_target()
{
gold_assert(parameters->target().machine_code() == elfcpp::EM_ARM
&& parameters->target().is_big_endian() == big_endian);
return static_cast<Target_arm<big_endian>*>(
parameters->sized_target<32, big_endian>());
}
// Whether relocation type uses LSB to distinguish THUMB addresses.
static bool
reloc_uses_thumb_bit(unsigned int r_type);
protected:
// Make an ELF object.
Object*
do_make_elf_object(const std::string&, Input_file*, off_t,
const elfcpp::Ehdr<32, big_endian>& ehdr);
Object*
do_make_elf_object(const std::string&, Input_file*, off_t,
const elfcpp::Ehdr<32, !big_endian>&)
{ gold_unreachable(); }
Object*
do_make_elf_object(const std::string&, Input_file*, off_t,
const elfcpp::Ehdr<64, false>&)
{ gold_unreachable(); }
Object*
do_make_elf_object(const std::string&, Input_file*, off_t,
const elfcpp::Ehdr<64, true>&)
{ gold_unreachable(); }
// Make an output section.
Output_section*
do_make_output_section(const char* name, elfcpp::Elf_Word type,
elfcpp::Elf_Xword flags)
{ return new Arm_output_section<big_endian>(name, type, flags); }
void
do_adjust_elf_header(unsigned char* view, int len) const;
// We only need to generate stubs, and hence perform relaxation if we are
// not doing relocatable linking.
bool
do_may_relax() const
{ return !parameters->options().relocatable(); }
bool
do_relax(int, const Input_objects*, Symbol_table*, Layout*);
private:
// The class which scans relocations.
class Scan
{
public:
Scan()
: issued_non_pic_error_(false)
{ }
inline void
local(Symbol_table* symtab, Layout* layout, Target_arm* target,
Sized_relobj<32, big_endian>* object,
unsigned int data_shndx,
Output_section* output_section,
const elfcpp::Rel<32, big_endian>& reloc, unsigned int r_type,
const elfcpp::Sym<32, big_endian>& lsym);
inline void
global(Symbol_table* symtab, Layout* layout, Target_arm* target,
Sized_relobj<32, big_endian>* object,
unsigned int data_shndx,
Output_section* output_section,
const elfcpp::Rel<32, big_endian>& reloc, unsigned int r_type,
Symbol* gsym);
private:
static void
unsupported_reloc_local(Sized_relobj<32, big_endian>*,
unsigned int r_type);
static void
unsupported_reloc_global(Sized_relobj<32, big_endian>*,
unsigned int r_type, Symbol*);
void
check_non_pic(Relobj*, unsigned int r_type);
// Almost identical to Symbol::needs_plt_entry except that it also
// handles STT_ARM_TFUNC.
static bool
symbol_needs_plt_entry(const Symbol* sym)
{
// An undefined symbol from an executable does not need a PLT entry.
if (sym->is_undefined() && !parameters->options().shared())
return false;
return (!parameters->doing_static_link()
&& (sym->type() == elfcpp::STT_FUNC
|| sym->type() == elfcpp::STT_ARM_TFUNC)
&& (sym->is_from_dynobj()
|| sym->is_undefined()
|| sym->is_preemptible()));
}
// Whether we have issued an error about a non-PIC compilation.
bool issued_non_pic_error_;
};
// The class which implements relocation.
class Relocate
{
public:
Relocate()
{ }
~Relocate()
{ }
// 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, big_endian>*, Target_arm*,
Output_section*, size_t relnum,
const elfcpp::Rel<32, big_endian>&,
unsigned int r_type, const Sized_symbol<32>*,
const Symbol_value<32>*,
unsigned char*, Arm_address,
section_size_type);
// Return whether we want to pass flag NON_PIC_REF for this
// reloc.
static inline bool
reloc_is_non_pic (unsigned int r_type)
{
switch (r_type)
{
case elfcpp::R_ARM_REL32:
case elfcpp::R_ARM_THM_CALL:
case elfcpp::R_ARM_CALL:
case elfcpp::R_ARM_JUMP24:
case elfcpp::R_ARM_PREL31:
case elfcpp::R_ARM_THM_ABS5:
case elfcpp::R_ARM_ABS8:
case elfcpp::R_ARM_ABS12:
case elfcpp::R_ARM_ABS16:
case elfcpp::R_ARM_BASE_ABS:
return true;
default:
return false;
}
}
};
// 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*);
};
// Get the GOT section, creating it if necessary.
Output_data_got<32, big_endian>*
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_;
}
// Create a PLT entry for a global symbol.
void
make_plt_entry(Symbol_table*, Layout*, Symbol*);
// Get the PLT section.
const Output_data_plt_arm<big_endian>*
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*);
// Return true if the symbol may need a COPY relocation.
// References from an executable object to non-function symbols
// defined in a dynamic object may need a COPY relocation.
bool
may_need_copy_reloc(Symbol* gsym)
{
return (gsym->type() != elfcpp::STT_ARM_TFUNC
&& gsym->may_need_copy_reloc());
}
// Add a potential copy relocation.
void
copy_reloc(Symbol_table* symtab, Layout* layout,
Sized_relobj<32, big_endian>* object,
unsigned int shndx, Output_section* output_section,
Symbol* sym, const elfcpp::Rel<32, big_endian>& reloc)
{
this->copy_relocs_.copy_reloc(symtab, layout,
symtab->get_sized_symbol<32>(sym),
object, shndx, output_section, reloc,
this->rel_dyn_section(layout));
}
// Whether two EABI versions are compatible.
static bool
are_eabi_versions_compatible(elfcpp::Elf_Word v1, elfcpp::Elf_Word v2);
// Merge processor-specific flags from input object and those in the ELF
// header of the output.
void
merge_processor_specific_flags(const std::string&, elfcpp::Elf_Word);
//
// Methods to support stub-generations.
//
// Group input sections for stub generation.
void
group_sections(Layout*, section_size_type, bool);
// Scan a relocation for stub generation.
void
scan_reloc_for_stub(const Relocate_info<32, big_endian>*, unsigned int,
const Sized_symbol<32>*, unsigned int,
const Symbol_value<32>*,
elfcpp::Elf_types<32>::Elf_Swxword, Arm_address);
// Scan a relocation section for stub.
template<int sh_type>
void
scan_reloc_section_for_stubs(
const Relocate_info<32, big_endian>* relinfo,
const unsigned char* prelocs,
size_t reloc_count,
Output_section* output_section,
bool needs_special_offset_handling,
const unsigned char* view,
elfcpp::Elf_types<32>::Elf_Addr view_address,
section_size_type);
// Information about this specific target which we pass to the
// general Target structure.
static const Target::Target_info arm_info;
// The types of GOT entries needed for this platform.
enum Got_type
{
GOT_TYPE_STANDARD = 0 // GOT entry for a regular symbol
};
typedef typename std::vector<Stub_table<big_endian>*> Stub_table_list;
// Map input section to Arm_input_section.
typedef Unordered_map<Input_section_specifier,
Arm_input_section<big_endian>*,
Input_section_specifier::hash,
Input_section_specifier::equal_to>
Arm_input_section_map;
// The GOT section.
Output_data_got<32, big_endian>* got_;
// The PLT section.
Output_data_plt_arm<big_endian>* plt_;
// The GOT PLT section.
Output_data_space* got_plt_;
// The dynamic reloc section.
Reloc_section* rel_dyn_;
// Relocs saved to avoid a COPY reloc.
Copy_relocs<elfcpp::SHT_REL, 32, big_endian> copy_relocs_;
// Space for variables copied with a COPY reloc.
Output_data_space* dynbss_;
// Vector of Stub_tables created.
Stub_table_list stub_tables_;
// Stub factory.
const Stub_factory &stub_factory_;
// Whether we can use BLX.
bool may_use_blx_;
// Whether we force PIC branch veneers.
bool should_force_pic_veneer_;
// Map for locating Arm_input_sections.
Arm_input_section_map arm_input_section_map_;
};
template<bool big_endian>
const Target::Target_info Target_arm<big_endian>::arm_info =
{
32, // size
big_endian, // is_big_endian
elfcpp::EM_ARM, // machine_code
false, // has_make_symbol
false, // has_resolve
false, // has_code_fill
true, // is_default_stack_executable
'\0', // wrap_char
"/usr/lib/libc.so.1", // dynamic_linker
0x8000, // 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
};
// Arm relocate functions class
//
template<bool big_endian>
class Arm_relocate_functions : public Relocate_functions<32, big_endian>
{
public:
typedef enum
{
STATUS_OKAY, // No error during relocation.
STATUS_OVERFLOW, // Relocation oveflow.
STATUS_BAD_RELOC // Relocation cannot be applied.
} Status;
private:
typedef Relocate_functions<32, big_endian> Base;
typedef Arm_relocate_functions<big_endian> This;
// Encoding of imm16 argument for movt and movw ARM instructions
// from ARM ARM:
//
// imm16 := imm4 | imm12
//
// f e d c b a 9 8 7 6 5 4 3 2 1 0 f e d c b a 9 8 7 6 5 4 3 2 1 0
// +-------+---------------+-------+-------+-----------------------+
// | | |imm4 | |imm12 |
// +-------+---------------+-------+-------+-----------------------+
// Extract the relocation addend from VAL based on the ARM
// instruction encoding described above.
static inline typename elfcpp::Swap<32, big_endian>::Valtype
extract_arm_movw_movt_addend(
typename elfcpp::Swap<32, big_endian>::Valtype val)
{
// According to the Elf ABI for ARM Architecture the immediate
// field is sign-extended to form the addend.
return utils::sign_extend<16>(((val >> 4) & 0xf000) | (val & 0xfff));
}
// Insert X into VAL based on the ARM instruction encoding described
// above.
static inline typename elfcpp::Swap<32, big_endian>::Valtype
insert_val_arm_movw_movt(
typename elfcpp::Swap<32, big_endian>::Valtype val,
typename elfcpp::Swap<32, big_endian>::Valtype x)
{
val &= 0xfff0f000;
val |= x & 0x0fff;
val |= (x & 0xf000) << 4;
return val;
}
// Encoding of imm16 argument for movt and movw Thumb2 instructions
// from ARM ARM:
//
// imm16 := imm4 | i | imm3 | imm8
//
// f e d c b a 9 8 7 6 5 4 3 2 1 0 f e d c b a 9 8 7 6 5 4 3 2 1 0
// +---------+-+-----------+-------++-+-----+-------+---------------+
// | |i| |imm4 || |imm3 | |imm8 |
// +---------+-+-----------+-------++-+-----+-------+---------------+
// Extract the relocation addend from VAL based on the Thumb2
// instruction encoding described above.
static inline typename elfcpp::Swap<32, big_endian>::Valtype
extract_thumb_movw_movt_addend(
typename elfcpp::Swap<32, big_endian>::Valtype val)
{
// According to the Elf ABI for ARM Architecture the immediate
// field is sign-extended to form the addend.
return utils::sign_extend<16>(((val >> 4) & 0xf000)
| ((val >> 15) & 0x0800)
| ((val >> 4) & 0x0700)
| (val & 0x00ff));
}
// Insert X into VAL based on the Thumb2 instruction encoding
// described above.
static inline typename elfcpp::Swap<32, big_endian>::Valtype
insert_val_thumb_movw_movt(
typename elfcpp::Swap<32, big_endian>::Valtype val,
typename elfcpp::Swap<32, big_endian>::Valtype x)
{
val &= 0xfbf08f00;
val |= (x & 0xf000) << 4;
val |= (x & 0x0800) << 15;
val |= (x & 0x0700) << 4;
val |= (x & 0x00ff);
return val;
}
// Handle ARM long branches.
static typename This::Status
arm_branch_common(unsigned int, const Relocate_info<32, big_endian>*,
unsigned char *, const Sized_symbol<32>*,
const Arm_relobj<big_endian>*, unsigned int,
const Symbol_value<32>*, Arm_address, Arm_address, bool);
// Handle THUMB long branches.
static typename This::Status
thumb_branch_common(unsigned int, const Relocate_info<32, big_endian>*,
unsigned char *, const Sized_symbol<32>*,
const Arm_relobj<big_endian>*, unsigned int,
const Symbol_value<32>*, Arm_address, Arm_address, bool);
public:
// R_ARM_ABS8: S + A
static inline typename This::Status
abs8(unsigned char *view,
const Sized_relobj<32, big_endian>* object,
const Symbol_value<32>* psymval)
{
typedef typename elfcpp::Swap<8, big_endian>::Valtype Valtype;
typedef typename elfcpp::Swap<32, big_endian>::Valtype Reltype;
Valtype* wv = reinterpret_cast<Valtype*>(view);
Valtype val = elfcpp::Swap<8, big_endian>::readval(wv);
Reltype addend = utils::sign_extend<8>(val);
Reltype x = psymval->value(object, addend);
val = utils::bit_select(val, x, 0xffU);
elfcpp::Swap<8, big_endian>::writeval(wv, val);
return (utils::has_signed_unsigned_overflow<8>(x)
? This::STATUS_OVERFLOW
: This::STATUS_OKAY);
}
// R_ARM_THM_ABS5: S + A
static inline typename This::Status
thm_abs5(unsigned char *view,
const Sized_relobj<32, big_endian>* object,
const Symbol_value<32>* psymval)
{
typedef typename elfcpp::Swap<16, big_endian>::Valtype Valtype;
typedef typename elfcpp::Swap<32, big_endian>::Valtype Reltype;
Valtype* wv = reinterpret_cast<Valtype*>(view);
Valtype val = elfcpp::Swap<16, big_endian>::readval(wv);
Reltype addend = (val & 0x7e0U) >> 6;
Reltype x = psymval->value(object, addend);
val = utils::bit_select(val, x << 6, 0x7e0U);
elfcpp::Swap<16, big_endian>::writeval(wv, val);
return (utils::has_overflow<5>(x)
? This::STATUS_OVERFLOW
: This::STATUS_OKAY);
}
// R_ARM_ABS12: S + A
static inline typename This::Status
abs12(unsigned char *view,
const Sized_relobj<32, big_endian>* object,
const Symbol_value<32>* psymval)
{
typedef typename elfcpp::Swap<32, big_endian>::Valtype Valtype;
typedef typename elfcpp::Swap<32, big_endian>::Valtype Reltype;
Valtype* wv = reinterpret_cast<Valtype*>(view);
Valtype val = elfcpp::Swap<32, big_endian>::readval(wv);
Reltype addend = val & 0x0fffU;
Reltype x = psymval->value(object, addend);
val = utils::bit_select(val, x, 0x0fffU);
elfcpp::Swap<32, big_endian>::writeval(wv, val);
return (utils::has_overflow<12>(x)
? This::STATUS_OVERFLOW
: This::STATUS_OKAY);
}
// R_ARM_ABS16: S + A
static inline typename This::Status
abs16(unsigned char *view,
const Sized_relobj<32, big_endian>* object,
const Symbol_value<32>* psymval)
{
typedef typename elfcpp::Swap<16, big_endian>::Valtype Valtype;
typedef typename elfcpp::Swap<32, big_endian>::Valtype Reltype;
Valtype* wv = reinterpret_cast<Valtype*>(view);
Valtype val = elfcpp::Swap<16, big_endian>::readval(wv);
Reltype addend = utils::sign_extend<16>(val);
Reltype x = psymval->value(object, addend);
val = utils::bit_select(val, x, 0xffffU);
elfcpp::Swap<16, big_endian>::writeval(wv, val);
return (utils::has_signed_unsigned_overflow<16>(x)
? This::STATUS_OVERFLOW
: This::STATUS_OKAY);
}
// R_ARM_ABS32: (S + A) | T
static inline typename This::Status
abs32(unsigned char *view,
const Sized_relobj<32, big_endian>* object,
const Symbol_value<32>* psymval,
Arm_address thumb_bit)
{
typedef typename elfcpp::Swap<32, big_endian>::Valtype Valtype;
Valtype* wv = reinterpret_cast<Valtype*>(view);
Valtype addend = elfcpp::Swap<32, big_endian>::readval(wv);
Valtype x = psymval->value(object, addend) | thumb_bit;
elfcpp::Swap<32, big_endian>::writeval(wv, x);
return This::STATUS_OKAY;
}
// R_ARM_REL32: (S + A) | T - P
static inline typename This::Status
rel32(unsigned char *view,
const Sized_relobj<32, big_endian>* object,
const Symbol_value<32>* psymval,
Arm_address address,
Arm_address thumb_bit)
{
typedef typename elfcpp::Swap<32, big_endian>::Valtype Valtype;
Valtype* wv = reinterpret_cast<Valtype*>(view);
Valtype addend = elfcpp::Swap<32, big_endian>::readval(wv);
Valtype x = (psymval->value(object, addend) | thumb_bit) - address;
elfcpp::Swap<32, big_endian>::writeval(wv, x);
return This::STATUS_OKAY;
}
// R_ARM_THM_CALL: (S + A) | T - P
static inline typename This::Status
thm_call(const Relocate_info<32, big_endian>* relinfo, unsigned char *view,
const Sized_symbol<32>* gsym, const Arm_relobj<big_endian>* object,
unsigned int r_sym, const Symbol_value<32>* psymval,
Arm_address address, Arm_address thumb_bit,
bool is_weakly_undefined_without_plt)
{
return thumb_branch_common(elfcpp::R_ARM_THM_CALL, relinfo, view, gsym,
object, r_sym, psymval, address, thumb_bit,
is_weakly_undefined_without_plt);
}
// R_ARM_THM_JUMP24: (S + A) | T - P
static inline typename This::Status
thm_jump24(const Relocate_info<32, big_endian>* relinfo, unsigned char *view,
const Sized_symbol<32>* gsym, const Arm_relobj<big_endian>* object,
unsigned int r_sym, const Symbol_value<32>* psymval,
Arm_address address, Arm_address thumb_bit,
bool is_weakly_undefined_without_plt)
{
return thumb_branch_common(elfcpp::R_ARM_THM_JUMP24, relinfo, view, gsym,
object, r_sym, psymval, address, thumb_bit,
is_weakly_undefined_without_plt);
}
// R_ARM_THM_XPC22: (S + A) | T - P
static inline typename This::Status
thm_xpc22(const Relocate_info<32, big_endian>* relinfo, unsigned char *view,
const Sized_symbol<32>* gsym, const Arm_relobj<big_endian>* object,
unsigned int r_sym, const Symbol_value<32>* psymval,
Arm_address address, Arm_address thumb_bit,
bool is_weakly_undefined_without_plt)
{
return thumb_branch_common(elfcpp::R_ARM_THM_XPC22, relinfo, view, gsym,
object, r_sym, psymval, address, thumb_bit,
is_weakly_undefined_without_plt);
}
// R_ARM_BASE_PREL: B(S) + A - P
static inline typename This::Status
base_prel(unsigned char* view,
Arm_address origin,
Arm_address address)
{
Base::rel32(view, origin - address);
return STATUS_OKAY;
}
// R_ARM_BASE_ABS: B(S) + A
static inline typename This::Status
base_abs(unsigned char* view,
Arm_address origin)
{
Base::rel32(view, origin);
return STATUS_OKAY;
}
// R_ARM_GOT_BREL: GOT(S) + A - GOT_ORG
static inline typename This::Status
got_brel(unsigned char* view,
typename elfcpp::Swap<32, big_endian>::Valtype got_offset)
{
Base::rel32(view, got_offset);
return This::STATUS_OKAY;
}
// R_ARM_GOT_PREL: GOT(S) + A – P
static inline typename This::Status
got_prel(unsigned char* view,
typename elfcpp::Swap<32, big_endian>::Valtype got_offset,
Arm_address address)
{
Base::rel32(view, got_offset - address);
return This::STATUS_OKAY;
}
// R_ARM_PLT32: (S + A) | T - P
static inline typename This::Status
plt32(const Relocate_info<32, big_endian>* relinfo,
unsigned char *view,
const Sized_symbol<32>* gsym,
const Arm_relobj<big_endian>* object,
unsigned int r_sym,
const Symbol_value<32>* psymval,
Arm_address address,
Arm_address thumb_bit,
bool is_weakly_undefined_without_plt)
{
return arm_branch_common(elfcpp::R_ARM_PLT32, relinfo, view, gsym,
object, r_sym, psymval, address, thumb_bit,
is_weakly_undefined_without_plt);
}
// R_ARM_XPC25: (S + A) | T - P
static inline typename This::Status
xpc25(const Relocate_info<32, big_endian>* relinfo,
unsigned char *view,
const Sized_symbol<32>* gsym,
const Arm_relobj<big_endian>* object,
unsigned int r_sym,
const Symbol_value<32>* psymval,
Arm_address address,
Arm_address thumb_bit,
bool is_weakly_undefined_without_plt)
{
return arm_branch_common(elfcpp::R_ARM_XPC25, relinfo, view, gsym,
object, r_sym, psymval, address, thumb_bit,
is_weakly_undefined_without_plt);
}
// R_ARM_CALL: (S + A) | T - P
static inline typename This::Status
call(const Relocate_info<32, big_endian>* relinfo,
unsigned char *view,
const Sized_symbol<32>* gsym,
const Arm_relobj<big_endian>* object,
unsigned int r_sym,
const Symbol_value<32>* psymval,
Arm_address address,
Arm_address thumb_bit,
bool is_weakly_undefined_without_plt)
{
return arm_branch_common(elfcpp::R_ARM_CALL, relinfo, view, gsym,
object, r_sym, psymval, address, thumb_bit,
is_weakly_undefined_without_plt);
}
// R_ARM_JUMP24: (S + A) | T - P
static inline typename This::Status
jump24(const Relocate_info<32, big_endian>* relinfo,
unsigned char *view,
const Sized_symbol<32>* gsym,
const Arm_relobj<big_endian>* object,
unsigned int r_sym,
const Symbol_value<32>* psymval,
Arm_address address,
Arm_address thumb_bit,
bool is_weakly_undefined_without_plt)
{
return arm_branch_common(elfcpp::R_ARM_JUMP24, relinfo, view, gsym,
object, r_sym, psymval, address, thumb_bit,
is_weakly_undefined_without_plt);
}
// R_ARM_PREL: (S + A) | T - P
static inline typename This::Status
prel31(unsigned char *view,
const Sized_relobj<32, big_endian>* object,
const Symbol_value<32>* psymval,
Arm_address address,
Arm_address thumb_bit)
{
typedef typename elfcpp::Swap<32, big_endian>::Valtype Valtype;
Valtype* wv = reinterpret_cast<Valtype*>(view);
Valtype val = elfcpp::Swap<32, big_endian>::readval(wv);
Valtype addend = utils::sign_extend<31>(val);
Valtype x = (psymval->value(object, addend) | thumb_bit) - address;
val = utils::bit_select(val, x, 0x7fffffffU);
elfcpp::Swap<32, big_endian>::writeval(wv, val);
return (utils::has_overflow<31>(x) ?
This::STATUS_OVERFLOW : This::STATUS_OKAY);
}
// R_ARM_MOVW_ABS_NC: (S + A) | T
static inline typename This::Status
movw_abs_nc(unsigned char *view,
const Sized_relobj<32, big_endian>* object,
const Symbol_value<32>* psymval,
Arm_address thumb_bit)
{
typedef typename elfcpp::Swap<32, big_endian>::Valtype Valtype;
Valtype* wv = reinterpret_cast<Valtype*>(view);
Valtype val = elfcpp::Swap<32, big_endian>::readval(wv);
Valtype addend = This::extract_arm_movw_movt_addend(val);
Valtype x = psymval->value(object, addend) | thumb_bit;
val = This::insert_val_arm_movw_movt(val, x);
elfcpp::Swap<32, big_endian>::writeval(wv, val);
return This::STATUS_OKAY;
}
// R_ARM_MOVT_ABS: S + A
static inline typename This::Status
movt_abs(unsigned char *view,
const Sized_relobj<32, big_endian>* object,
const Symbol_value<32>* psymval)
{
typedef typename elfcpp::Swap<32, big_endian>::Valtype Valtype;
Valtype* wv = reinterpret_cast<Valtype*>(view);
Valtype val = elfcpp::Swap<32, big_endian>::readval(wv);
Valtype addend = This::extract_arm_movw_movt_addend(val);
Valtype x = psymval->value(object, addend) >> 16;
val = This::insert_val_arm_movw_movt(val, x);
elfcpp::Swap<32, big_endian>::writeval(wv, val);
return This::STATUS_OKAY;
}
// R_ARM_THM_MOVW_ABS_NC: S + A | T
static inline typename This::Status
thm_movw_abs_nc(unsigned char *view,
const Sized_relobj<32, big_endian>* object,
const Symbol_value<32>* psymval,
Arm_address thumb_bit)
{
typedef typename elfcpp::Swap<16, big_endian>::Valtype Valtype;
typedef typename elfcpp::Swap<32, big_endian>::Valtype Reltype;
Valtype* wv = reinterpret_cast<Valtype*>(view);
Reltype val = ((elfcpp::Swap<16, big_endian>::readval(wv) << 16)
| elfcpp::Swap<16, big_endian>::readval(wv + 1));
Reltype addend = extract_thumb_movw_movt_addend(val);
Reltype x = psymval->value(object, addend) | thumb_bit;
val = This::insert_val_thumb_movw_movt(val, x);
elfcpp::Swap<16, big_endian>::writeval(wv, val >> 16);
elfcpp::Swap<16, big_endian>::writeval(wv + 1, val & 0xffff);
return This::STATUS_OKAY;
}
// R_ARM_THM_MOVT_ABS: S + A
static inline typename This::Status
thm_movt_abs(unsigned char *view,
const Sized_relobj<32, big_endian>* object,
const Symbol_value<32>* psymval)
{
typedef typename elfcpp::Swap<16, big_endian>::Valtype Valtype;
typedef typename elfcpp::Swap<32, big_endian>::Valtype Reltype;
Valtype* wv = reinterpret_cast<Valtype*>(view);
Reltype val = ((elfcpp::Swap<16, big_endian>::readval(wv) << 16)
| elfcpp::Swap<16, big_endian>::readval(wv + 1));
Reltype addend = This::extract_thumb_movw_movt_addend(val);
Reltype x = psymval->value(object, addend) >> 16;
val = This::insert_val_thumb_movw_movt(val, x);
elfcpp::Swap<16, big_endian>::writeval(wv, val >> 16);
elfcpp::Swap<16, big_endian>::writeval(wv + 1, val & 0xffff);
return This::STATUS_OKAY;
}
// R_ARM_MOVW_PREL_NC: (S + A) | T - P
static inline typename This::Status
movw_prel_nc(unsigned char *view,
const Sized_relobj<32, big_endian>* object,
const Symbol_value<32>* psymval,
Arm_address address,
Arm_address thumb_bit)
{
typedef typename elfcpp::Swap<32, big_endian>::Valtype Valtype;
Valtype* wv = reinterpret_cast<Valtype*>(view);
Valtype val = elfcpp::Swap<32, big_endian>::readval(wv);
Valtype addend = This::extract_arm_movw_movt_addend(val);
Valtype x = (psymval->value(object, addend) | thumb_bit) - address;
val = This::insert_val_arm_movw_movt(val, x);
elfcpp::Swap<32, big_endian>::writeval(wv, val);
return This::STATUS_OKAY;
}
// R_ARM_MOVT_PREL: S + A - P
static inline typename This::Status
movt_prel(unsigned char *view,
const Sized_relobj<32, big_endian>* object,
const Symbol_value<32>* psymval,
Arm_address address)
{
typedef typename elfcpp::Swap<32, big_endian>::Valtype Valtype;
Valtype* wv = reinterpret_cast<Valtype*>(view);
Valtype val = elfcpp::Swap<32, big_endian>::readval(wv);
Valtype addend = This::extract_arm_movw_movt_addend(val);
Valtype x = (psymval->value(object, addend) - address) >> 16;
val = This::insert_val_arm_movw_movt(val, x);
elfcpp::Swap<32, big_endian>::writeval(wv, val);
return This::STATUS_OKAY;
}
// R_ARM_THM_MOVW_PREL_NC: (S + A) | T - P
static inline typename This::Status
thm_movw_prel_nc(unsigned char *view,
const Sized_relobj<32, big_endian>* object,
const Symbol_value<32>* psymval,
Arm_address address,
Arm_address thumb_bit)
{
typedef typename elfcpp::Swap<16, big_endian>::Valtype Valtype;
typedef typename elfcpp::Swap<32, big_endian>::Valtype Reltype;
Valtype* wv = reinterpret_cast<Valtype*>(view);
Reltype val = (elfcpp::Swap<16, big_endian>::readval(wv) << 16)
| elfcpp::Swap<16, big_endian>::readval(wv + 1);
Reltype addend = This::extract_thumb_movw_movt_addend(val);
Reltype x = (psymval->value(object, addend) | thumb_bit) - address;
val = This::insert_val_thumb_movw_movt(val, x);
elfcpp::Swap<16, big_endian>::writeval(wv, val >> 16);
elfcpp::Swap<16, big_endian>::writeval(wv + 1, val & 0xffff);
return This::STATUS_OKAY;
}
// R_ARM_THM_MOVT_PREL: S + A - P
static inline typename This::Status
thm_movt_prel(unsigned char *view,
const Sized_relobj<32, big_endian>* object,
const Symbol_value<32>* psymval,
Arm_address address)
{
typedef typename elfcpp::Swap<16, big_endian>::Valtype Valtype;
typedef typename elfcpp::Swap<32, big_endian>::Valtype Reltype;
Valtype* wv = reinterpret_cast<Valtype*>(view);
Reltype val = (elfcpp::Swap<16, big_endian>::readval(wv) << 16)
| elfcpp::Swap<16, big_endian>::readval(wv + 1);
Reltype addend = This::extract_thumb_movw_movt_addend(val);
Reltype x = (psymval->value(object, addend) - address) >> 16;
val = This::insert_val_thumb_movw_movt(val, x);
elfcpp::Swap<16, big_endian>::writeval(wv, val >> 16);
elfcpp::Swap<16, big_endian>::writeval(wv + 1, val & 0xffff);
return This::STATUS_OKAY;
}
};
// Relocate ARM long branches. This handles relocation types
// R_ARM_CALL, R_ARM_JUMP24, R_ARM_PLT32 and R_ARM_XPC25.
// If IS_WEAK_UNDEFINED_WITH_PLT is true. The target symbol is weakly
// undefined and we do not use PLT in this relocation. In such a case,
// the branch is converted into an NOP.
template<bool big_endian>
typename Arm_relocate_functions<big_endian>::Status
Arm_relocate_functions<big_endian>::arm_branch_common(
unsigned int r_type,
const Relocate_info<32, big_endian>* relinfo,
unsigned char *view,
const Sized_symbol<32>* gsym,
const Arm_relobj<big_endian>* object,
unsigned int r_sym,
const Symbol_value<32>* psymval,
Arm_address address,
Arm_address thumb_bit,
bool is_weakly_undefined_without_plt)
{
typedef typename elfcpp::Swap<32, big_endian>::Valtype Valtype;
Valtype* wv = reinterpret_cast<Valtype*>(view);
Valtype val = elfcpp::Swap<32, big_endian>::readval(wv);
bool insn_is_b = (((val >> 28) & 0xf) <= 0xe)
&& ((val & 0x0f000000UL) == 0x0a000000UL);
bool insn_is_uncond_bl = (val & 0xff000000UL) == 0xeb000000UL;
bool insn_is_cond_bl = (((val >> 28) & 0xf) < 0xe)
&& ((val & 0x0f000000UL) == 0x0b000000UL);
bool insn_is_blx = (val & 0xfe000000UL) == 0xfa000000UL;
bool insn_is_any_branch = (val & 0x0e000000UL) == 0x0a000000UL;
// Check that the instruction is valid.
if (r_type == elfcpp::R_ARM_CALL)
{
if (!insn_is_uncond_bl && !insn_is_blx)
return This::STATUS_BAD_RELOC;
}
else if (r_type == elfcpp::R_ARM_JUMP24)
{
if (!insn_is_b && !insn_is_cond_bl)
return This::STATUS_BAD_RELOC;
}
else if (r_type == elfcpp::R_ARM_PLT32)
{
if (!insn_is_any_branch)
return This::STATUS_BAD_RELOC;
}
else if (r_type == elfcpp::R_ARM_XPC25)
{
// FIXME: AAELF document IH0044C does not say much about it other
// than it being obsolete.
if (!insn_is_any_branch)
return This::STATUS_BAD_RELOC;
}
else
gold_unreachable();
// A branch to an undefined weak symbol is turned into a jump to
// the next instruction unless a PLT entry will be created.
// Do the same for local undefined symbols.
// The jump to the next instruction is optimized as a NOP depending
// on the architecture.
const Target_arm<big_endian>* arm_target =
Target_arm<big_endian>::default_target();
if (is_weakly_undefined_without_plt)
{
Valtype cond = val & 0xf0000000U;
if (arm_target->may_use_arm_nop())
val = cond | 0x0320f000;
else
val = cond | 0x01a00000; // Using pre-UAL nop: mov r0, r0.
elfcpp::Swap<32, big_endian>::writeval(wv, val);
return This::STATUS_OKAY;
}
Valtype addend = utils::sign_extend<26>(val << 2);
Valtype branch_target = psymval->value(object, addend);
int32_t branch_offset = branch_target - address;
// We need a stub if the branch offset is too large or if we need
// to switch mode.
bool may_use_blx = arm_target->may_use_blx();
Reloc_stub* stub = NULL;
if ((branch_offset > ARM_MAX_FWD_BRANCH_OFFSET)
|| (branch_offset < ARM_MAX_BWD_BRANCH_OFFSET)
|| ((thumb_bit != 0) && !(may_use_blx && r_type == elfcpp::R_ARM_CALL)))
{
Stub_type stub_type =
Reloc_stub::stub_type_for_reloc(r_type, address, branch_target,
(thumb_bit != 0));
if (stub_type != arm_stub_none)
{
Stub_table<big_endian>* stub_table =
object->stub_table(relinfo->data_shndx);
gold_assert(stub_table != NULL);
Reloc_stub::Key stub_key(stub_type, gsym, object, r_sym, addend);
stub = stub_table->find_reloc_stub(stub_key);
gold_assert(stub != NULL);
thumb_bit = stub->stub_template()->entry_in_thumb_mode() ? 1 : 0;
branch_target = stub_table->address() + stub->offset() + addend;
branch_offset = branch_target - address;
gold_assert((branch_offset <= ARM_MAX_FWD_BRANCH_OFFSET)
&& (branch_offset >= ARM_MAX_BWD_BRANCH_OFFSET));
}
}
// At this point, if we still need to switch mode, the instruction
// must either be a BLX or a BL that can be converted to a BLX.
if (thumb_bit != 0)
{
// Turn BL to BLX.
gold_assert(may_use_blx && r_type == elfcpp::R_ARM_CALL);
val = (val & 0xffffff) | 0xfa000000 | ((branch_offset & 2) << 23);
}
val = utils::bit_select(val, (branch_offset >> 2), 0xffffffUL);
elfcpp::Swap<32, big_endian>::writeval(wv, val);
return (utils::has_overflow<26>(branch_offset)
? This::STATUS_OVERFLOW : This::STATUS_OKAY);
}
// Relocate THUMB long branches. This handles relocation types
// R_ARM_THM_CALL, R_ARM_THM_JUMP24 and R_ARM_THM_XPC22.
// If IS_WEAK_UNDEFINED_WITH_PLT is true. The target symbol is weakly
// undefined and we do not use PLT in this relocation. In such a case,
// the branch is converted into an NOP.
template<bool big_endian>
typename Arm_relocate_functions<big_endian>::Status
Arm_relocate_functions<big_endian>::thumb_branch_common(
unsigned int r_type,
const Relocate_info<32, big_endian>* relinfo,
unsigned char *view,
const Sized_symbol<32>* gsym,
const Arm_relobj<big_endian>* object,
unsigned int r_sym,
const Symbol_value<32>* psymval,
Arm_address address,
Arm_address thumb_bit,
bool is_weakly_undefined_without_plt)
{
typedef typename elfcpp::Swap<16, big_endian>::Valtype Valtype;
Valtype* wv = reinterpret_cast<Valtype*>(view);
uint32_t upper_insn = elfcpp::Swap<16, big_endian>::readval(wv);
uint32_t lower_insn = elfcpp::Swap<16, big_endian>::readval(wv + 1);
// FIXME: These tests are too loose and do not take THUMB/THUMB-2 difference
// into account.
bool is_bl_insn = (lower_insn & 0x1000U) == 0x1000U;
bool is_blx_insn = (lower_insn & 0x1000U) == 0x0000U;
// Check that the instruction is valid.
if (r_type == elfcpp::R_ARM_THM_CALL)
{
if (!is_bl_insn && !is_blx_insn)
return This::STATUS_BAD_RELOC;
}
else if (r_type == elfcpp::R_ARM_THM_JUMP24)
{
// This cannot be a BLX.
if (!is_bl_insn)
return This::STATUS_BAD_RELOC;
}
else if (r_type == elfcpp::R_ARM_THM_XPC22)
{
// Check for Thumb to Thumb call.
if (!is_blx_insn)
return This::STATUS_BAD_RELOC;
if (thumb_bit != 0)
{
gold_warning(_("%s: Thumb BLX instruction targets "
"thumb function '%s'."),
object->name().c_str(),
(gsym ? gsym->name() : "(local)"));
// Convert BLX to BL.
lower_insn |= 0x1000U;
}
}
else
gold_unreachable();
// A branch to an undefined weak symbol is turned into a jump to
// the next instruction unless a PLT entry will be created.
// The jump to the next instruction is optimized as a NOP.W for
// Thumb-2 enabled architectures.
const Target_arm<big_endian>* arm_target =
Target_arm<big_endian>::default_target();
if (is_weakly_undefined_without_plt)
{
if (arm_target->may_use_thumb2_nop())
{
elfcpp::Swap<16, big_endian>::writeval(wv, 0xf3af);
elfcpp::Swap<16, big_endian>::writeval(wv + 1, 0x8000);
}
else
{
elfcpp::Swap<16, big_endian>::writeval(wv, 0xe000);
elfcpp::Swap<16, big_endian>::writeval(wv + 1, 0xbf00);
}
return This::STATUS_OKAY;
}
// Fetch the addend. We use the Thumb-2 encoding (backwards compatible
// with Thumb-1) involving the J1 and J2 bits.
uint32_t s = (upper_insn & (1 << 10)) >> 10;
uint32_t upper = upper_insn & 0x3ff;
uint32_t lower = lower_insn & 0x7ff;
uint32_t j1 = (lower_insn & (1 << 13)) >> 13;
uint32_t j2 = (lower_insn & (1 << 11)) >> 11;
uint32_t i1 = j1 ^ s ? 0 : 1;
uint32_t i2 = j2 ^ s ? 0 : 1;
int32_t addend = (i1 << 23) | (i2 << 22) | (upper << 12) | (lower << 1);
// Sign extend.
addend = (addend | ((s ? 0 : 1) << 24)) - (1 << 24);
Arm_address branch_target = psymval->value(object, addend);
int32_t branch_offset = branch_target - address;
// We need a stub if the branch offset is too large or if we need
// to switch mode.
bool may_use_blx = arm_target->may_use_blx();
bool thumb2 = arm_target->using_thumb2();
if ((!thumb2
&& (branch_offset > THM_MAX_FWD_BRANCH_OFFSET
|| (branch_offset < THM_MAX_BWD_BRANCH_OFFSET)))
|| (thumb2
&& (branch_offset > THM2_MAX_FWD_BRANCH_OFFSET
|| (branch_offset < THM2_MAX_BWD_BRANCH_OFFSET)))
|| ((thumb_bit == 0)
&& (((r_type == elfcpp::R_ARM_THM_CALL) && !may_use_blx)
|| r_type == elfcpp::R_ARM_THM_JUMP24)))
{
Stub_type stub_type =
Reloc_stub::stub_type_for_reloc(r_type, address, branch_target,
(thumb_bit != 0));
if (stub_type != arm_stub_none)
{
Stub_table<big_endian>* stub_table =
object->stub_table(relinfo->data_shndx);
gold_assert(stub_table != NULL);
Reloc_stub::Key stub_key(stub_type, gsym, object, r_sym, addend);
Reloc_stub* stub = stub_table->find_reloc_stub(stub_key);
gold_assert(stub != NULL);
thumb_bit = stub->stub_template()->entry_in_thumb_mode() ? 1 : 0;
branch_target = stub_table->address() + stub->offset() + addend;
branch_offset = branch_target - address;
}
}
// At this point, if we still need to switch mode, the instruction
// must either be a BLX or a BL that can be converted to a BLX.
if (thumb_bit == 0)
{
gold_assert(may_use_blx
&& (r_type == elfcpp::R_ARM_THM_CALL
|| r_type == elfcpp::R_ARM_THM_XPC22));
// Make sure this is a BLX.
lower_insn &= ~0x1000U;
}
else
{
// Make sure this is a BL.
lower_insn |= 0x1000U;
}
uint32_t reloc_sign = (branch_offset < 0) ? 1 : 0;
uint32_t relocation = static_cast<uint32_t>(branch_offset);
if ((lower_insn & 0x5000U) == 0x4000U)
// For a BLX instruction, make sure that the relocation is rounded up
// to a word boundary. This follows the semantics of the instruction
// which specifies that bit 1 of the target address will come from bit
// 1 of the base address.
relocation = (relocation + 2U) & ~3U;
// Put BRANCH_OFFSET back into the insn. Assumes two's complement.
// We use the Thumb-2 encoding, which is safe even if dealing with
// a Thumb-1 instruction by virtue of our overflow check above. */
upper_insn = (upper_insn & ~0x7ffU)
| ((relocation >> 12) & 0x3ffU)
| (reloc_sign << 10);
lower_insn = (lower_insn & ~0x2fffU)
| (((!((relocation >> 23) & 1U)) ^ reloc_sign) << 13)
| (((!((relocation >> 22) & 1U)) ^ reloc_sign) << 11)
| ((relocation >> 1) & 0x7ffU);
elfcpp::Swap<16, big_endian>::writeval(wv, upper_insn);
elfcpp::Swap<16, big_endian>::writeval(wv + 1, lower_insn);
return ((thumb2
? utils::has_overflow<25>(relocation)
: utils::has_overflow<23>(relocation))
? This::STATUS_OVERFLOW
: This::STATUS_OKAY);
}
// Get the GOT section, creating it if necessary.
template<bool big_endian>
Output_data_got<32, big_endian>*
Target_arm<big_endian>::got_section(Symbol_table* symtab, Layout* layout)
{
if (this->got_ == NULL)
{
gold_assert(symtab != NULL && layout != NULL);
this->got_ = new Output_data_got<32, big_endian>();
Output_section* os;
os = layout->add_output_section_data(".got", elfcpp::SHT_PROGBITS,
(elfcpp::SHF_ALLOC
| elfcpp::SHF_WRITE),
this->got_, false);
os->set_is_relro();
// The old GNU linker creates a .got.plt section. We just
// create another set of data in the .got section. Note that we
// always create a PLT if we create a GOT, although the PLT
// might be empty.
this->got_plt_ = new Output_data_space(4, "** GOT PLT");
os = layout->add_output_section_data(".got", elfcpp::SHT_PROGBITS,
(elfcpp::SHF_ALLOC
| elfcpp::SHF_WRITE),
this->got_plt_, false);
os->set_is_relro();
// The first three entries are reserved.
this->got_plt_->set_current_data_size(3 * 4);
// Define _GLOBAL_OFFSET_TABLE_ at the start of the PLT.
symtab->define_in_output_data("_GLOBAL_OFFSET_TABLE_", NULL,
this->got_plt_,
0, 0, elfcpp::STT_OBJECT,
elfcpp::STB_LOCAL,
elfcpp::STV_HIDDEN, 0,
false, false);
}
return this->got_;
}
// Get the dynamic reloc section, creating it if necessary.
template<bool big_endian>
typename Target_arm<big_endian>::Reloc_section*
Target_arm<big_endian>::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_, true);
}
return this->rel_dyn_;
}
// Insn_template methods.
// Return byte size of an instruction template.
size_t
Insn_template::size() const
{
switch (this->type())
{
case THUMB16_TYPE:
return 2;
case ARM_TYPE:
case THUMB32_TYPE:
case DATA_TYPE:
return 4;
default:
gold_unreachable();
}
}
// Return alignment of an instruction template.
unsigned
Insn_template::alignment() const
{
switch (this->type())
{
case THUMB16_TYPE:
case THUMB32_TYPE:
return 2;
case ARM_TYPE:
case DATA_TYPE:
return 4;
default:
gold_unreachable();
}
}
// Stub_template methods.
Stub_template::Stub_template(
Stub_type type, const Insn_template* insns,
size_t insn_count)
: type_(type), insns_(insns), insn_count_(insn_count), alignment_(1),
entry_in_thumb_mode_(false), relocs_()
{
off_t offset = 0;
// Compute byte size and alignment of stub template.
for (size_t i = 0; i < insn_count; i++)
{
unsigned insn_alignment = insns[i].alignment();
size_t insn_size = insns[i].size();
gold_assert((offset & (insn_alignment - 1)) == 0);
this->alignment_ = std::max(this->alignment_, insn_alignment);
switch (insns[i].type())
{
case Insn_template::THUMB16_TYPE:
if (i == 0)
this->entry_in_thumb_mode_ = true;
break;
case Insn_template::THUMB32_TYPE:
if (insns[i].r_type() != elfcpp::R_ARM_NONE)
this->relocs_.push_back(Reloc(i, offset));
if (i == 0)
this->entry_in_thumb_mode_ = true;
break;
case Insn_template::ARM_TYPE:
// Handle cases where the target is encoded within the
// instruction.
if (insns[i].r_type() == elfcpp::R_ARM_JUMP24)
this->relocs_.push_back(Reloc(i, offset));
break;
case Insn_template::DATA_TYPE:
// Entry point cannot be data.
gold_assert(i != 0);
this->relocs_.push_back(Reloc(i, offset));
break;
default:
gold_unreachable();
}
offset += insn_size;
}
this->size_ = offset;
}
// Reloc_stub::Key methods.
// Dump a Key as a string for debugging.
std::string
Reloc_stub::Key::name() const
{
if (this->r_sym_ == invalid_index)
{
// Global symbol key name
// <stub-type>:<symbol name>:<addend>.
const std::string sym_name = this->u_.symbol->name();
// We need to print two hex number and two colons. So just add 100 bytes
// to the symbol name size.
size_t len = sym_name.size() + 100;
char* buffer = new char[len];
int c = snprintf(buffer, len, "%d:%s:%x", this->stub_type_,
sym_name.c_str(), this->addend_);
gold_assert(c > 0 && c < static_cast<int>(len));
delete[] buffer;
return std::string(buffer);
}
else
{
// local symbol key name
// <stub-type>:<object>:<r_sym>:<addend>.
const size_t len = 200;
char buffer[len];
int c = snprintf(buffer, len, "%d:%p:%u:%x", this->stub_type_,
this->u_.relobj, this->r_sym_, this->addend_);
gold_assert(c > 0 && c < static_cast<int>(len));
return std::string(buffer);
}
}
// Reloc_stub methods.
// Determine the type of stub needed, if any, for a relocation of R_TYPE at
// LOCATION to DESTINATION.
// This code is based on the arm_type_of_stub function in
// bfd/elf32-arm.c. We have changed the interface a liitle to keep the Stub
// class simple.
Stub_type
Reloc_stub::stub_type_for_reloc(
unsigned int r_type,
Arm_address location,
Arm_address destination,
bool target_is_thumb)
{
Stub_type stub_type = arm_stub_none;
// This is a bit ugly but we want to avoid using a templated class for
// big and little endianities.
bool may_use_blx;
bool should_force_pic_veneer;
bool thumb2;
bool thumb_only;
if (parameters->target().is_big_endian())
{
const Target_arm<true>* big_endian_target =
Target_arm<true>::default_target();
may_use_blx = big_endian_target->may_use_blx();
should_force_pic_veneer = big_endian_target->should_force_pic_veneer();
thumb2 = big_endian_target->using_thumb2();
thumb_only = big_endian_target->using_thumb_only();
}
else
{
const Target_arm<false>* little_endian_target =
Target_arm<false>::default_target();
may_use_blx = little_endian_target->may_use_blx();
should_force_pic_veneer = little_endian_target->should_force_pic_veneer();
thumb2 = little_endian_target->using_thumb2();
thumb_only = little_endian_target->using_thumb_only();
}
int64_t branch_offset = (int64_t)destination - location;
if (r_type == elfcpp::R_ARM_THM_CALL || r_type == elfcpp::R_ARM_THM_JUMP24)
{
// Handle cases where:
// - this call goes too far (different Thumb/Thumb2 max
// distance)
// - it's a Thumb->Arm call and blx is not available, or it's a
// Thumb->Arm branch (not bl). A stub is needed in this case.
if ((!thumb2
&& (branch_offset > THM_MAX_FWD_BRANCH_OFFSET
|| (branch_offset < THM_MAX_BWD_BRANCH_OFFSET)))
|| (thumb2
&& (branch_offset > THM2_MAX_FWD_BRANCH_OFFSET
|| (branch_offset < THM2_MAX_BWD_BRANCH_OFFSET)))
|| ((!target_is_thumb)
&& (((r_type == elfcpp::R_ARM_THM_CALL) && !may_use_blx)
|| (r_type == elfcpp::R_ARM_THM_JUMP24))))
{
if (target_is_thumb)
{
// Thumb to thumb.
if (!thumb_only)
{
stub_type = (parameters->options().shared()
|| should_force_pic_veneer)
// PIC stubs.
? ((may_use_blx
&& (r_type == elfcpp::R_ARM_THM_CALL))
// V5T and above. Stub starts with ARM code, so
// we must be able to switch mode before
// reaching it, which is only possible for 'bl'
// (ie R_ARM_THM_CALL relocation).
? arm_stub_long_branch_any_thumb_pic
// On V4T, use Thumb code only.
: arm_stub_long_branch_v4t_thumb_thumb_pic)
// non-PIC stubs.
: ((may_use_blx
&& (r_type == elfcpp::R_ARM_THM_CALL))
? arm_stub_long_branch_any_any // V5T and above.
: arm_stub_long_branch_v4t_thumb_thumb); // V4T.
}
else
{
stub_type = (parameters->options().shared()
|| should_force_pic_veneer)
? arm_stub_long_branch_thumb_only_pic // PIC stub.
: arm_stub_long_branch_thumb_only; // non-PIC stub.
}
}
else
{
// Thumb to arm.
// FIXME: We should check that the input section is from an
// object that has interwork enabled.
stub_type = (parameters->options().shared()
|| should_force_pic_veneer)
// PIC stubs.
? ((may_use_blx
&& (r_type == elfcpp::R_ARM_THM_CALL))
? arm_stub_long_branch_any_arm_pic // V5T and above.
: arm_stub_long_branch_v4t_thumb_arm_pic) // V4T.
// non-PIC stubs.
: ((may_use_blx
&& (r_type == elfcpp::R_ARM_THM_CALL))
? arm_stub_long_branch_any_any // V5T and above.
: arm_stub_long_branch_v4t_thumb_arm); // V4T.
// Handle v4t short branches.
if ((stub_type == arm_stub_long_branch_v4t_thumb_arm)
&& (branch_offset <= THM_MAX_FWD_BRANCH_OFFSET)
&& (branch_offset >= THM_MAX_BWD_BRANCH_OFFSET))
stub_type = arm_stub_short_branch_v4t_thumb_arm;
}
}
}
else if (r_type == elfcpp::R_ARM_CALL
|| r_type == elfcpp::R_ARM_JUMP24
|| r_type == elfcpp::R_ARM_PLT32)
{
if (target_is_thumb)
{
// Arm to thumb.
// FIXME: We should check that the input section is from an
// object that has interwork enabled.
// We have an extra 2-bytes reach because of
// the mode change (bit 24 (H) of BLX encoding).
if (branch_offset > (ARM_MAX_FWD_BRANCH_OFFSET + 2)
|| (branch_offset < ARM_MAX_BWD_BRANCH_OFFSET)
|| ((r_type == elfcpp::R_ARM_CALL) && !may_use_blx)
|| (r_type == elfcpp::R_ARM_JUMP24)
|| (r_type == elfcpp::R_ARM_PLT32))
{
stub_type = (parameters->options().shared()
|| should_force_pic_veneer)
// PIC stubs.
? (may_use_blx
? arm_stub_long_branch_any_thumb_pic// V5T and above.
: arm_stub_long_branch_v4t_arm_thumb_pic) // V4T stub.
// non-PIC stubs.
: (may_use_blx
? arm_stub_long_branch_any_any // V5T and above.
: arm_stub_long_branch_v4t_arm_thumb); // V4T.
}
}
else
{
// Arm to arm.
if (branch_offset > ARM_MAX_FWD_BRANCH_OFFSET
|| (branch_offset < ARM_MAX_BWD_BRANCH_OFFSET))
{
stub_type = (parameters->options().shared()
|| should_force_pic_veneer)
? arm_stub_long_branch_any_arm_pic // PIC stubs.
: arm_stub_long_branch_any_any; /// non-PIC.
}
}
}
return stub_type;
}
// Template to implement do_write for a specific target endianity.
template<bool big_endian>
void inline
Reloc_stub::do_fixed_endian_write(unsigned char* view,
section_size_type view_size)
{
const Stub_template* stub_template = this->stub_template();
const Insn_template* insns = stub_template->insns();
// FIXME: We do not handle BE8 encoding yet.
unsigned char* pov = view;
for (size_t i = 0; i < stub_template->insn_count(); i++)
{
switch (insns[i].type())
{
case Insn_template::THUMB16_TYPE:
// Non-zero reloc addends are only used in Cortex-A8 stubs.
gold_assert(insns[i].reloc_addend() == 0);
elfcpp::Swap<16, big_endian>::writeval(pov, insns[i].data() & 0xffff);
break;
case Insn_template::THUMB32_TYPE:
{
uint32_t hi = (insns[i].data() >> 16) & 0xffff;
uint32_t lo = insns[i].data() & 0xffff;
elfcpp::Swap<16, big_endian>::writeval(pov, hi);
elfcpp::Swap<16, big_endian>::writeval(pov + 2, lo);
}
break;
case Insn_template::ARM_TYPE:
case Insn_template::DATA_TYPE:
elfcpp::Swap<32, big_endian>::writeval(pov, insns[i].data());
break;
default:
gold_unreachable();
}
pov += insns[i].size();
}
gold_assert(static_cast<section_size_type>(pov - view) == view_size);
}
// Write a reloc stub to VIEW with endianity specified by BIG_ENDIAN.
void
Reloc_stub::do_write(unsigned char* view, section_size_type view_size,
bool big_endian)
{
if (big_endian)
this->do_fixed_endian_write<true>(view, view_size);
else
this->do_fixed_endian_write<false>(view, view_size);
}
// Stub_factory methods.
Stub_factory::Stub_factory()
{
// The instruction template sequences are declared as static
// objects and initialized first time the constructor runs.
// Arm/Thumb -> Arm/Thumb long branch stub. On V5T and above, use blx
// to reach the stub if necessary.
static const Insn_template elf32_arm_stub_long_branch_any_any[] =
{
Insn_template::arm_insn(0xe51ff004), // ldr pc, [pc, #-4]
Insn_template::data_word(0, elfcpp::R_ARM_ABS32, 0),
// dcd R_ARM_ABS32(X)
};
// V4T Arm -> Thumb long branch stub. Used on V4T where blx is not
// available.
static const Insn_template elf32_arm_stub_long_branch_v4t_arm_thumb[] =
{
Insn_template::arm_insn(0xe59fc000), // ldr ip, [pc, #0]
Insn_template::arm_insn(0xe12fff1c), // bx ip
Insn_template::data_word(0, elfcpp::R_ARM_ABS32, 0),
// dcd R_ARM_ABS32(X)
};
// Thumb -> Thumb long branch stub. Used on M-profile architectures.
static const Insn_template elf32_arm_stub_long_branch_thumb_only[] =
{
Insn_template::thumb16_insn(0xb401), // push {r0}
Insn_template::thumb16_insn(0x4802), // ldr r0, [pc, #8]
Insn_template::thumb16_insn(0x4684), // mov ip, r0
Insn_template::thumb16_insn(0xbc01), // pop {r0}
Insn_template::thumb16_insn(0x4760), // bx ip
Insn_template::thumb16_insn(0xbf00), // nop
Insn_template::data_word(0, elfcpp::R_ARM_ABS32, 0),
// dcd R_ARM_ABS32(X)
};
// V4T Thumb -> Thumb long branch stub. Using the stack is not
// allowed.
static const Insn_template elf32_arm_stub_long_branch_v4t_thumb_thumb[] =
{
Insn_template::thumb16_insn(0x4778), // bx pc
Insn_template::thumb16_insn(0x46c0), // nop
Insn_template::arm_insn(0xe59fc000), // ldr ip, [pc, #0]
Insn_template::arm_insn(0xe12fff1c), // bx ip
Insn_template::data_word(0, elfcpp::R_ARM_ABS32, 0),
// dcd R_ARM_ABS32(X)
};
// V4T Thumb -> ARM long branch stub. Used on V4T where blx is not
// available.
static const Insn_template elf32_arm_stub_long_branch_v4t_thumb_arm[] =
{
Insn_template::thumb16_insn(0x4778), // bx pc
Insn_template::thumb16_insn(0x46c0), // nop
Insn_template::arm_insn(0xe51ff004), // ldr pc, [pc, #-4]
Insn_template::data_word(0, elfcpp::R_ARM_ABS32, 0),
// dcd R_ARM_ABS32(X)
};
// V4T Thumb -> ARM short branch stub. Shorter variant of the above
// one, when the destination is close enough.
static const Insn_template elf32_arm_stub_short_branch_v4t_thumb_arm[] =
{
Insn_template::thumb16_insn(0x4778), // bx pc
Insn_template::thumb16_insn(0x46c0), // nop
Insn_template::arm_rel_insn(0xea000000, -8), // b (X-8)
};
// ARM/Thumb -> ARM long branch stub, PIC. On V5T and above, use
// blx to reach the stub if necessary.
static const Insn_template elf32_arm_stub_long_branch_any_arm_pic[] =
{
Insn_template::arm_insn(0xe59fc000), // ldr r12, [pc]
Insn_template::arm_insn(0xe08ff00c), // add pc, pc, ip
Insn_template::data_word(0, elfcpp::R_ARM_REL32, -4),
// dcd R_ARM_REL32(X-4)
};
// ARM/Thumb -> Thumb long branch stub, PIC. On V5T and above, use
// blx to reach the stub if necessary. We can not add into pc;
// it is not guaranteed to mode switch (different in ARMv6 and
// ARMv7).
static const Insn_template elf32_arm_stub_long_branch_any_thumb_pic[] =
{
Insn_template::arm_insn(0xe59fc004), // ldr r12, [pc, #4]
Insn_template::arm_insn(0xe08fc00c), // add ip, pc, ip
Insn_template::arm_insn(0xe12fff1c), // bx ip
Insn_template::data_word(0, elfcpp::R_ARM_REL32, 0),
// dcd R_ARM_REL32(X)
};
// V4T ARM -> ARM long branch stub, PIC.
static const Insn_template elf32_arm_stub_long_branch_v4t_arm_thumb_pic[] =
{
Insn_template::arm_insn(0xe59fc004), // ldr ip, [pc, #4]
Insn_template::arm_insn(0xe08fc00c), // add ip, pc, ip
Insn_template::arm_insn(0xe12fff1c), // bx ip
Insn_template::data_word(0, elfcpp::R_ARM_REL32, 0),
// dcd R_ARM_REL32(X)
};
// V4T Thumb -> ARM long branch stub, PIC.
static const Insn_template elf32_arm_stub_long_branch_v4t_thumb_arm_pic[] =
{
Insn_template::thumb16_insn(0x4778), // bx pc
Insn_template::thumb16_insn(0x46c0), // nop
Insn_template::arm_insn(0xe59fc000), // ldr ip, [pc, #0]
Insn_template::arm_insn(0xe08cf00f), // add pc, ip, pc
Insn_template::data_word(0, elfcpp::R_ARM_REL32, -4),
// dcd R_ARM_REL32(X)
};
// Thumb -> Thumb long branch stub, PIC. Used on M-profile
// architectures.
static const Insn_template elf32_arm_stub_long_branch_thumb_only_pic[] =
{
Insn_template::thumb16_insn(0xb401), // push {r0}
Insn_template::thumb16_insn(0x4802), // ldr r0, [pc, #8]
Insn_template::thumb16_insn(0x46fc), // mov ip, pc
Insn_template::thumb16_insn(0x4484), // add ip, r0
Insn_template::thumb16_insn(0xbc01), // pop {r0}
Insn_template::thumb16_insn(0x4760), // bx ip
Insn_template::data_word(0, elfcpp::R_ARM_REL32, 4),
// dcd R_ARM_REL32(X)
};
// V4T Thumb -> Thumb long branch stub, PIC. Using the stack is not
// allowed.
static const Insn_template elf32_arm_stub_long_branch_v4t_thumb_thumb_pic[] =
{
Insn_template::thumb16_insn(0x4778), // bx pc
Insn_template::thumb16_insn(0x46c0), // nop
Insn_template::arm_insn(0xe59fc004), // ldr ip, [pc, #4]
Insn_template::arm_insn(0xe08fc00c), // add ip, pc, ip
Insn_template::arm_insn(0xe12fff1c), // bx ip
Insn_template::data_word(0, elfcpp::R_ARM_REL32, 0),
// dcd R_ARM_REL32(X)
};
// Cortex-A8 erratum-workaround stubs.
// Stub used for conditional branches (which may be beyond +/-1MB away,
// so we can't use a conditional branch to reach this stub).
// original code:
//
// b<cond> X
// after:
//
static const Insn_template elf32_arm_stub_a8_veneer_b_cond[] =
{
Insn_template::thumb16_bcond_insn(0xd001), // b<cond>.n true
Insn_template::thumb32_b_insn(0xf000b800, -4), // b.w after
Insn_template::thumb32_b_insn(0xf000b800, -4) // true:
// b.w X
};
// Stub used for b.w and bl.w instructions.
static const Insn_template elf32_arm_stub_a8_veneer_b[] =
{
Insn_template::thumb32_b_insn(0xf000b800, -4) // b.w dest
};
static const Insn_template elf32_arm_stub_a8_veneer_bl[] =
{
Insn_template::thumb32_b_insn(0xf000b800, -4) // b.w dest
};
// Stub used for Thumb-2 blx.w instructions. We modified the original blx.w
// instruction (which switches to ARM mode) to point to this stub. Jump to
// the real destination using an ARM-mode branch.
const Insn_template elf32_arm_stub_a8_veneer_blx[] =
{
Insn_template::arm_rel_insn(0xea000000, -8) // b dest
};
// Fill in the stub template look-up table. Stub templates are constructed
// per instance of Stub_factory for fast look-up without locking
// in a thread-enabled environment.
this->stub_templates_[arm_stub_none] =
new Stub_template(arm_stub_none, NULL, 0);
#define DEF_STUB(x) \
do \
{ \
size_t array_size \
= sizeof(elf32_arm_stub_##x) / sizeof(elf32_arm_stub_##x[0]); \
Stub_type type = arm_stub_##x; \
this->stub_templates_[type] = \
new Stub_template(type, elf32_arm_stub_##x, array_size); \
} \
while (0);
DEF_STUBS
#undef DEF_STUB
}
// Stub_table methods.
// Add a STUB with using KEY. Caller is reponsible for avoid adding
// if already a STUB with the same key has been added.
template<bool big_endian>
void
Stub_table<big_endian>::add_reloc_stub(
Reloc_stub* stub,
const Reloc_stub::Key& key)
{
const Stub_template* stub_template = stub->stub_template();
gold_assert(stub_template->type() == key.stub_type());
this->reloc_stubs_[key] = stub;
if (this->addralign_ < stub_template->alignment())
this->addralign_ = stub_template->alignment();
this->has_been_changed_ = true;
}
template<bool big_endian>
void
Stub_table<big_endian>::relocate_stubs(
const Relocate_info<32, big_endian>* relinfo,
Target_arm<big_endian>* arm_target,
Output_section* output_section,
unsigned char* view,
Arm_address address,
section_size_type view_size)
{
// If we are passed a view bigger than the stub table's. we need to
// adjust the view.
gold_assert(address == this->address()
&& (view_size
== static_cast<section_size_type>(this->data_size())));
for (typename Reloc_stub_map::const_iterator p = this->reloc_stubs_.begin();
p != this->reloc_stubs_.end();
++p)
{
Reloc_stub* stub = p->second;
const Stub_template* stub_template = stub->stub_template();
if (stub_template->reloc_count() != 0)
{
// Adjust view to cover the stub only.
section_size_type offset = stub->offset();
section_size_type stub_size = stub_template->size();
gold_assert(offset + stub_size <= view_size);
arm_target->relocate_stub(stub, relinfo, output_section,
view + offset, address + offset,
stub_size);
}
}
}
// Reset address and file offset.
template<bool big_endian>
void
Stub_table<big_endian>::do_reset_address_and_file_offset()
{
off_t off = 0;
uint64_t max_addralign = 1;
for (typename Reloc_stub_map::const_iterator p = this->reloc_stubs_.begin();
p != this->reloc_stubs_.end();
++p)
{
Reloc_stub* stub = p->second;
const Stub_template* stub_template = stub->stub_template();
uint64_t stub_addralign = stub_template->alignment();
max_addralign = std::max(max_addralign, stub_addralign);
off = align_address(off, stub_addralign);
stub->set_offset(off);
stub->reset_destination_address();
off += stub_template->size();
}
this->addralign_ = max_addralign;
this->set_current_data_size_for_child(off);
}
// Write out the stubs to file.
template<bool big_endian>
void
Stub_table<big_endian>::do_write(Output_file* of)
{
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);
for (typename Reloc_stub_map::const_iterator p = this->reloc_stubs_.begin();
p != this->reloc_stubs_.end();
++p)
{
Reloc_stub* stub = p->second;
Arm_address address = this->address() + stub->offset();
gold_assert(address
== align_address(address,
stub->stub_template()->alignment()));
stub->write(oview + stub->offset(), stub->stub_template()->size(),
big_endian);
}
of->write_output_view(this->offset(), oview_size, oview);
}
// Arm_input_section methods.
// Initialize an Arm_input_section.
template<bool big_endian>
void
Arm_input_section<big_endian>::init()
{
Relobj* relobj = this->relobj();
unsigned int shndx = this->shndx();
// Cache these to speed up size and alignment queries. It is too slow
// to call section_addraglin and section_size every time.
this->original_addralign_ = relobj->section_addralign(shndx);
this->original_size_ = relobj->section_size(shndx);
// We want to make this look like the original input section after
// output sections are finalized.
Output_section* os = relobj->output_section(shndx);
off_t offset = relobj->output_section_offset(shndx);
gold_assert(os != NULL && !relobj->is_output_section_offset_invalid(shndx));
this->set_address(os->address() + offset);
this->set_file_offset(os->offset() + offset);
this->set_current_data_size(this->original_size_);
this->finalize_data_size();
}
template<bool big_endian>
void
Arm_input_section<big_endian>::do_write(Output_file* of)
{
// We have to write out the original section content.
section_size_type section_size;
const unsigned char* section_contents =
this->relobj()->section_contents(this->shndx(), &section_size, false);
of->write(this->offset(), section_contents, section_size);
// If this owns a stub table and it is not empty, write it.
if (this->is_stub_table_owner() && !this->stub_table_->empty())
this->stub_table_->write(of);
}
// Finalize data size.
template<bool big_endian>
void
Arm_input_section<big_endian>::set_final_data_size()
{
// If this owns a stub table, finalize its data size as well.
if (this->is_stub_table_owner())
{
uint64_t address = this->address();
// The stub table comes after the original section contents.
address += this->original_size_;
address = align_address(address, this->stub_table_->addralign());
off_t offset = this->offset() + (address - this->address());
this->stub_table_->set_address_and_file_offset(address, offset);
address += this->stub_table_->data_size();
gold_assert(address == this->address() + this->current_data_size());
}
this->set_data_size(this->current_data_size());
}
// Reset address and file offset.
template<bool big_endian>
void
Arm_input_section<big_endian>::do_reset_address_and_file_offset()
{
// Size of the original input section contents.
off_t off = convert_types<off_t, uint64_t>(this->original_size_);
// If this is a stub table owner, account for the stub table size.
if (this->is_stub_table_owner())
{
Stub_table<big_endian>* stub_table = this->stub_table_;
// Reset the stub table's address and file offset. The
// current data size for child will be updated after that.
stub_table_->reset_address_and_file_offset();
off = align_address(off, stub_table_->addralign());
off += stub_table->current_data_size();
}
this->set_current_data_size(off);
}
// Arm_output_section methods.
// Create a stub group for input sections from BEGIN to END. OWNER
// points to the input section to be the owner a new stub table.
template<bool big_endian>
void
Arm_output_section<big_endian>::create_stub_group(
Input_section_list::const_iterator begin,
Input_section_list::const_iterator end,
Input_section_list::const_iterator owner,
Target_arm<big_endian>* target,
std::vector<Output_relaxed_input_section*>* new_relaxed_sections)
{
// Currently we convert ordinary input sections into relaxed sections only
// at this point but we may want to support creating relaxed input section
// very early. So we check here to see if owner is already a relaxed
// section.
Arm_input_section<big_endian>* arm_input_section;
if (owner->is_relaxed_input_section())
{
arm_input_section =
Arm_input_section<big_endian>::as_arm_input_section(
owner->relaxed_input_section());
}
else
{
gold_assert(owner->is_input_section());
// Create a new relaxed input section.
arm_input_section =
target->new_arm_input_section(owner->relobj(), owner->shndx());
new_relaxed_sections->push_back(arm_input_section);
}
// Create a stub table.
Stub_table<big_endian>* stub_table =
target->new_stub_table(arm_input_section);
arm_input_section->set_stub_table(stub_table);
Input_section_list::const_iterator p = begin;
Input_section_list::const_iterator prev_p;
// Look for input sections or relaxed input sections in [begin ... end].
do
{
if (p->is_input_section() || p->is_relaxed_input_section())
{
// The stub table information for input sections live
// in their objects.
Arm_relobj<big_endian>* arm_relobj =
Arm_relobj<big_endian>::as_arm_relobj(p->relobj());
arm_relobj->set_stub_table(p->shndx(), stub_table);
}
prev_p = p++;
}
while (prev_p != end);
}
// Group input sections for stub generation. GROUP_SIZE is roughly the limit
// of stub groups. We grow a stub group by adding input section until the
// size is just below GROUP_SIZE. The last input section will be converted
// into a stub table. If STUB_ALWAYS_AFTER_BRANCH is false, we also add
// input section after the stub table, effectively double the group size.
//
// This is similar to the group_sections() function in elf32-arm.c but is
// implemented differently.
template<bool big_endian>
void
Arm_output_section<big_endian>::group_sections(
section_size_type group_size,
bool stubs_always_after_branch,
Target_arm<big_endian>* target)
{
// We only care about sections containing code.
if ((this->flags() & elfcpp::SHF_EXECINSTR) == 0)
return;
// States for grouping.
typedef enum
{
// No group is being built.
NO_GROUP,
// A group is being built but the stub table is not found yet.
// We keep group a stub group until the size is just under GROUP_SIZE.
// The last input section in the group will be used as the stub table.
FINDING_STUB_SECTION,
// A group is being built and we have already found a stub table.
// We enter this state to grow a stub group by adding input section
// after the stub table. This effectively doubles the group size.
HAS_STUB_SECTION
} State;
// Any newly created relaxed sections are stored here.
std::vector<Output_relaxed_input_section*> new_relaxed_sections;
State state = NO_GROUP;
section_size_type off = 0;
section_size_type group_begin_offset = 0;
section_size_type group_end_offset = 0;
section_size_type stub_table_end_offset = 0;
Input_section_list::const_iterator group_begin =
this->input_sections().end();
Input_section_list::const_iterator stub_table =
this->input_sections().end();
Input_section_list::const_iterator group_end = this->input_sections().end();
for (Input_section_list::const_iterator p = this->input_sections().begin();
p != this->input_sections().end();
++p)
{
section_size_type section_begin_offset =
align_address(off, p->addralign());
section_size_type section_end_offset =
section_begin_offset + p->data_size();
// Check to see if we should group the previously seens sections.
switch (state)
{
case NO_GROUP:
break;
case FINDING_STUB_SECTION:
// Adding this section makes the group larger than GROUP_SIZE.
if (section_end_offset - group_begin_offset >= group_size)
{
if (stubs_always_after_branch)
{
gold_assert(group_end != this->input_sections().end());
this->create_stub_group(group_begin, group_end, group_end,
target, &new_relaxed_sections);
state = NO_GROUP;
}
else
{
// But wait, there's more! Input sections up to
// stub_group_size bytes after the stub table can be
// handled by it too.
state = HAS_STUB_SECTION;
stub_table = group_end;
stub_table_end_offset = group_end_offset;
}
}
break;
case HAS_STUB_SECTION:
// Adding this section makes the post stub-section group larger
// than GROUP_SIZE.
if (section_end_offset - stub_table_end_offset >= group_size)
{
gold_assert(group_end != this->input_sections().end());
this->create_stub_group(group_begin, group_end, stub_table,
target, &new_relaxed_sections);
state = NO_GROUP;
}
break;
default:
gold_unreachable();
}
// If we see an input section and currently there is no group, start
// a new one. Skip any empty sections.
if ((p->is_input_section() || p->is_relaxed_input_section())
&& (p->relobj()->section_size(p->shndx()) != 0))
{
if (state == NO_GROUP)
{
state = FINDING_STUB_SECTION;
group_begin = p;
group_begin_offset = section_begin_offset;
}
// Keep track of the last input section seen.
group_end = p;
group_end_offset = section_end_offset;
}
off = section_end_offset;
}
// Create a stub group for any ungrouped sections.
if (state == FINDING_STUB_SECTION || state == HAS_STUB_SECTION)
{
gold_assert(group_end != this->input_sections().end());
this->create_stub_group(group_begin, group_end,
(state == FINDING_STUB_SECTION
? group_end
: stub_table),
target, &new_relaxed_sections);
}
// Convert input section into relaxed input section in a batch.
if (!new_relaxed_sections.empty())
this->convert_input_sections_to_relaxed_sections(new_relaxed_sections);
// Update the section offsets
for (size_t i = 0; i < new_relaxed_sections.size(); ++i)
{
Arm_relobj<big_endian>* arm_relobj =
Arm_relobj<big_endian>::as_arm_relobj(
new_relaxed_sections[i]->relobj());
unsigned int shndx = new_relaxed_sections[i]->shndx();
// Tell Arm_relobj that this input section is converted.
arm_relobj->convert_input_section_to_relaxed_section(shndx);
}
}
// Arm_relobj methods.
// Scan relocations for stub generation.
template<bool big_endian>
void
Arm_relobj<big_endian>::scan_sections_for_stubs(
Target_arm<big_endian>* arm_target,
const Symbol_table* symtab,
const Layout* layout)
{
unsigned int shnum = this->shnum();
const unsigned int shdr_size = elfcpp::Elf_sizes<32>::shdr_size;
// Read the section headers.
const unsigned char* pshdrs = this->get_view(this->elf_file()->shoff(),
shnum * shdr_size,
true, true);
// To speed up processing, we set up hash tables for fast lookup of
// input offsets to output addresses.
this->initialize_input_to_output_maps();
const Relobj::Output_sections& out_sections(this->output_sections());
Relocate_info<32, big_endian> relinfo;
relinfo.symtab = symtab;
relinfo.layout = layout;
relinfo.object = this;
const unsigned char* p = pshdrs + shdr_size;
for (unsigned int i = 1; i < shnum; ++i, p += shdr_size)
{
typename elfcpp::Shdr<32, big_endian> shdr(p);
unsigned int sh_type = shdr.get_sh_type();
if (sh_type != elfcpp::SHT_REL && sh_type != elfcpp::SHT_RELA)
continue;
off_t sh_size = shdr.get_sh_size();
if (sh_size == 0)
continue;
unsigned int index = this->adjust_shndx(shdr.get_sh_info());
if (index >= this->shnum())
{
// Ignore reloc section with bad info. This error will be
// reported in the final link.
continue;
}
Output_section* os = out_sections[index];
if (os == NULL)
{
// This relocation section is against a section which we
// discarded.
continue;
}
Arm_address output_offset = this->get_output_section_offset(index);
if (this->adjust_shndx(shdr.get_sh_link()) != this->symtab_shndx())
{
// Ignore reloc section with unexpected symbol table. The
// error will be reported in the final link.
continue;
}
const unsigned char* prelocs = this->get_view(shdr.get_sh_offset(),
sh_size, true, false);
unsigned int reloc_size;
if (sh_type == elfcpp::SHT_REL)
reloc_size = elfcpp::Elf_sizes<32>::rel_size;
else
reloc_size = elfcpp::Elf_sizes<32>::rela_size;
if (reloc_size != shdr.get_sh_entsize())
{
// Ignore reloc section with unexpected entsize. The error
// will be reported in the final link.
continue;
}
size_t reloc_count = sh_size / reloc_size;
if (static_cast<off_t>(reloc_count * reloc_size) != sh_size)
{
// Ignore reloc section with uneven size. The error will be
// reported in the final link.
continue;
}
gold_assert(output_offset != invalid_address
|| this->relocs_must_follow_section_writes());
// Get the section contents. This does work for the case in which
// we modify the contents of an input section. We need to pass the
// output view under such circumstances.
section_size_type input_view_size = 0;
const unsigned char* input_view =
this->section_contents(index, &input_view_size, false);
relinfo.reloc_shndx = i;
relinfo.data_shndx = index;
arm_target->scan_section_for_stubs(&relinfo, sh_type, prelocs,
reloc_count, os,
output_offset == invalid_address,
input_view,
os->address(),
input_view_size);
}
// After we've done the relocations, we release the hash tables,
// since we no longer need them.
this->free_input_to_output_maps();
}
// Count the local symbols. The ARM backend needs to know if a symbol
// is a THUMB function or not. For global symbols, it is easy because
// the Symbol object keeps the ELF symbol type. For local symbol it is
// harder because we cannot access this information. So we override the
// do_count_local_symbol in parent and scan local symbols to mark
// THUMB functions. This is not the most efficient way but I do not want to
// slow down other ports by calling a per symbol targer hook inside
// Sized_relobj<size, big_endian>::do_count_local_symbols.
template<bool big_endian>
void
Arm_relobj<big_endian>::do_count_local_symbols(
Stringpool_template<char>* pool,
Stringpool_template<char>* dynpool)
{
// We need to fix-up the values of any local symbols whose type are
// STT_ARM_TFUNC.
// Ask parent to count the local symbols.
Sized_relobj<32, big_endian>::do_count_local_symbols(pool, dynpool);
const unsigned int loccount = this->local_symbol_count();
if (loccount == 0)
return;
// Intialize the thumb function bit-vector.
std::vector<bool> empty_vector(loccount, false);
this->local_symbol_is_thumb_function_.swap(empty_vector);
// Read the symbol table section header.
const unsigned int symtab_shndx = this->symtab_shndx();
elfcpp::Shdr<32, big_endian>
symtabshdr(this, this->elf_file()->section_header(symtab_shndx));
gold_assert(symtabshdr.get_sh_type() == elfcpp::SHT_SYMTAB);
// Read the local symbols.
const int sym_size =elfcpp::Elf_sizes<32>::sym_size;
gold_assert(loccount == symtabshdr.get_sh_info());
off_t locsize = loccount * sym_size;
const unsigned char* psyms = this->get_view(symtabshdr.get_sh_offset(),
locsize, true, true);
// Loop over the local symbols and mark any local symbols pointing
// to THUMB functions.
// Skip the first dummy symbol.
psyms += sym_size;
typename Sized_relobj<32, big_endian>::Local_values* plocal_values =
this->local_values();
for (unsigned int i = 1; i < loccount; ++i, psyms += sym_size)
{
elfcpp::Sym<32, big_endian> sym(psyms);
elfcpp::STT st_type = sym.get_st_type();
Symbol_value<32>& lv((*plocal_values)[i]);
Arm_address input_value = lv.input_value();
if (st_type == elfcpp::STT_ARM_TFUNC
|| (st_type == elfcpp::STT_FUNC && ((input_value & 1) != 0)))
{
// This is a THUMB function. Mark this and canonicalize the
// symbol value by setting LSB.
this->local_symbol_is_thumb_function_[i] = true;
if ((input_value & 1) == 0)
lv.set_input_value(input_value | 1);
}
}
}
// Relocate sections.
template<bool big_endian>
void
Arm_relobj<big_endian>::do_relocate_sections(
const Symbol_table* symtab,
const Layout* layout,
const unsigned char* pshdrs,
typename Sized_relobj<32, big_endian>::Views* pviews)
{
// Call parent to relocate sections.
Sized_relobj<32, big_endian>::do_relocate_sections(symtab, layout, pshdrs,
pviews);
// We do not generate stubs if doing a relocatable link.
if (parameters->options().relocatable())
return;
// Relocate stub tables.
unsigned int shnum = this->shnum();
Target_arm<big_endian>* arm_target =
Target_arm<big_endian>::default_target();
Relocate_info<32, big_endian> relinfo;
relinfo.symtab = symtab;
relinfo.layout = layout;
relinfo.object = this;
for (unsigned int i = 1; i < shnum; ++i)
{
Arm_input_section<big_endian>* arm_input_section =
arm_target->find_arm_input_section(this, i);
if (arm_input_section == NULL
|| !arm_input_section->is_stub_table_owner()
|| arm_input_section->stub_table()->empty())
continue;
// We cannot discard a section if it owns a stub table.
Output_section* os = this->output_section(i);
gold_assert(os != NULL);
relinfo.reloc_shndx = elfcpp::SHN_UNDEF;
relinfo.reloc_shdr = NULL;
relinfo.data_shndx = i;
relinfo.data_shdr = pshdrs + i * elfcpp::Elf_sizes<32>::shdr_size;
gold_assert((*pviews)[i].view != NULL);
// We are passed the output section view. Adjust it to cover the
// stub table only.
Stub_table<big_endian>* stub_table = arm_input_section->stub_table();
gold_assert((stub_table->address() >= (*pviews)[i].address)
&& ((stub_table->address() + stub_table->data_size())
<= (*pviews)[i].address + (*pviews)[i].view_size));
off_t offset = stub_table->address() - (*pviews)[i].address;
unsigned char* view = (*pviews)[i].view + offset;
Arm_address address = stub_table->address();
section_size_type view_size = stub_table->data_size();
stub_table->relocate_stubs(&relinfo, arm_target, os, view, address,
view_size);
}
}
// Read the symbol information.
template<bool big_endian>
void
Arm_relobj<big_endian>::do_read_symbols(Read_symbols_data* sd)
{
// Call parent class to read symbol information.
Sized_relobj<32, big_endian>::do_read_symbols(sd);
// Read processor-specific flags in ELF file header.
const unsigned char* pehdr = this->get_view(elfcpp::file_header_offset,
elfcpp::Elf_sizes<32>::ehdr_size,
true, false);
elfcpp::Ehdr<32, big_endian> ehdr(pehdr);
this->processor_specific_flags_ = ehdr.get_e_flags();
}
// Arm_dynobj methods.
// Read the symbol information.
template<bool big_endian>
void
Arm_dynobj<big_endian>::do_read_symbols(Read_symbols_data* sd)
{
// Call parent class to read symbol information.
Sized_dynobj<32, big_endian>::do_read_symbols(sd);
// Read processor-specific flags in ELF file header.
const unsigned char* pehdr = this->get_view(elfcpp::file_header_offset,
elfcpp::Elf_sizes<32>::ehdr_size,
true, false);
elfcpp::Ehdr<32, big_endian> ehdr(pehdr);
this->processor_specific_flags_ = ehdr.get_e_flags();
}
// Stub_addend_reader methods.
// Read the addend of a REL relocation of type R_TYPE at VIEW.
template<bool big_endian>
elfcpp::Elf_types<32>::Elf_Swxword
Stub_addend_reader<elfcpp::SHT_REL, big_endian>::operator()(
unsigned int r_type,
const unsigned char* view,
const typename Reloc_types<elfcpp::SHT_REL, 32, big_endian>::Reloc&) const
{
switch (r_type)
{
case elfcpp::R_ARM_CALL:
case elfcpp::R_ARM_JUMP24:
case elfcpp::R_ARM_PLT32:
{
typedef typename elfcpp::Swap<32, big_endian>::Valtype Valtype;
const Valtype* wv = reinterpret_cast<const Valtype*>(view);
Valtype val = elfcpp::Swap<32, big_endian>::readval(wv);
return utils::sign_extend<26>(val << 2);
}
case elfcpp::R_ARM_THM_CALL:
case elfcpp::R_ARM_THM_JUMP24:
case elfcpp::R_ARM_THM_XPC22:
{
// Fetch the addend. We use the Thumb-2 encoding (backwards
// compatible with Thumb-1) involving the J1 and J2 bits.
typedef typename elfcpp::Swap<16, big_endian>::Valtype Valtype;
const Valtype* wv = reinterpret_cast<const Valtype*>(view);
Valtype upper_insn = elfcpp::Swap<16, big_endian>::readval(wv);
Valtype lower_insn = elfcpp::Swap<16, big_endian>::readval(wv + 1);
uint32_t s = (upper_insn & (1 << 10)) >> 10;
uint32_t upper = upper_insn & 0x3ff;
uint32_t lower = lower_insn & 0x7ff;
uint32_t j1 = (lower_insn & (1 << 13)) >> 13;
uint32_t j2 = (lower_insn & (1 << 11)) >> 11;
uint32_t i1 = j1 ^ s ? 0 : 1;
uint32_t i2 = j2 ^ s ? 0 : 1;
return utils::sign_extend<25>((s << 24) | (i1 << 23) | (i2 << 22)
| (upper << 12) | (lower << 1));
}
case elfcpp::R_ARM_THM_JUMP19:
{
typedef typename elfcpp::Swap<16, big_endian>::Valtype Valtype;
const Valtype* wv = reinterpret_cast<const Valtype*>(view);
Valtype upper_insn = elfcpp::Swap<16, big_endian>::readval(wv);
Valtype lower_insn = elfcpp::Swap<16, big_endian>::readval(wv + 1);
// Reconstruct the top three bits and squish the two 11 bit pieces
// together.
uint32_t S = (upper_insn & 0x0400) >> 10;
uint32_t J1 = (lower_insn & 0x2000) >> 13;
uint32_t J2 = (lower_insn & 0x0800) >> 11;
uint32_t upper =
(S << 8) | (J2 << 7) | (J1 << 6) | (upper_insn & 0x003f);
uint32_t lower = (lower_insn & 0x07ff);
return utils::sign_extend<23>((upper << 12) | (lower << 1));
}
default:
gold_unreachable();
}
}
// A class to handle the PLT data.
template<bool big_endian>
class Output_data_plt_arm : public Output_section_data
{
public:
typedef Output_data_reloc<elfcpp::SHT_REL, true, 32, big_endian>
Reloc_section;
Output_data_plt_arm(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_; }
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:
// Template for the first PLT entry.
static const uint32_t first_plt_entry[5];
// Template for subsequent PLT entries.
static const uint32_t plt_entry[3];
// Set the final size.
void
set_final_data_size()
{
this->set_data_size(sizeof(first_plt_entry)
+ this->count_ * sizeof(plt_entry));
}
// Write out the PLT data.
void
do_write(Output_file*);
// The reloc section.
Reloc_section* 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.
template<bool big_endian>
Output_data_plt_arm<big_endian>::Output_data_plt_arm(Layout* layout,
Output_data_space* got_plt)
: Output_section_data(4), 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_, true);
}
template<bool big_endian>
void
Output_data_plt_arm<big_endian>::do_adjust_output_section(Output_section* os)
{
os->set_entsize(0);
}
// Add an entry to the PLT.
template<bool big_endian>
void
Output_data_plt_arm<big_endian>::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_) * sizeof(plt_entry)
+ sizeof(first_plt_entry));
++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_ARM_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.
}
// ARM PLTs.
// FIXME: This is not very flexible. Right now this has only been tested
// on armv5te. If we are to support additional architecture features like
// Thumb-2 or BE8, we need to make this more flexible like GNU ld.
// The first entry in the PLT.
template<bool big_endian>
const uint32_t Output_data_plt_arm<big_endian>::first_plt_entry[5] =
{
0xe52de004, // str lr, [sp, #-4]!
0xe59fe004, // ldr lr, [pc, #4]
0xe08fe00e, // add lr, pc, lr
0xe5bef008, // ldr pc, [lr, #8]!
0x00000000, // &GOT[0] - .
};
// Subsequent entries in the PLT.
template<bool big_endian>
const uint32_t Output_data_plt_arm<big_endian>::plt_entry[3] =
{
0xe28fc600, // add ip, pc, #0xNN00000
0xe28cca00, // add ip, ip, #0xNN000
0xe5bcf000, // ldr pc, [ip, #0xNNN]!
};
// Write out the PLT. This uses the hand-coded instructions above,
// and adjusts them as needed. This is all specified by the arm ELF
// Processor Supplement.
template<bool big_endian>
void
Output_data_plt_arm<big_endian>::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;
Arm_address plt_address = this->address();
Arm_address got_address = this->got_plt_->address();
// Write first PLT entry. All but the last word are constants.
const size_t num_first_plt_words = (sizeof(first_plt_entry)
/ sizeof(plt_entry[0]));
for (size_t i = 0; i < num_first_plt_words - 1; i++)
elfcpp::Swap<32, big_endian>::writeval(pov + i * 4, first_plt_entry[i]);
// Last word in first PLT entry is &GOT[0] - .
elfcpp::Swap<32, big_endian>::writeval(pov + 16,
got_address - (plt_address + 16));
pov += sizeof(first_plt_entry);
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 = sizeof(first_plt_entry);
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 += sizeof(plt_entry),
got_pov += 4,
plt_offset += sizeof(plt_entry),
plt_rel_offset += rel_size,
got_offset += 4)
{
// Set and adjust the PLT entry itself.
int32_t offset = ((got_address + got_offset)
- (plt_address + plt_offset + 8));
gold_assert(offset >= 0 && offset < 0x0fffffff);
uint32_t plt_insn0 = plt_entry[0] | ((offset >> 20) & 0xff);
elfcpp::Swap<32, big_endian>::writeval(pov, plt_insn0);
uint32_t plt_insn1 = plt_entry[1] | ((offset >> 12) & 0xff);
elfcpp::Swap<32, big_endian>::writeval(pov + 4, plt_insn1);
uint32_t plt_insn2 = plt_entry[2] | (offset & 0xfff);
elfcpp::Swap<32, big_endian>::writeval(pov + 8, plt_insn2);
// Set the entry in the GOT.
elfcpp::Swap<32, big_endian>::writeval(got_pov, plt_address);
}
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.
template<bool big_endian>
void
Target_arm<big_endian>::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_arm<big_endian>(layout, this->got_plt_);
layout->add_output_section_data(".plt", elfcpp::SHT_PROGBITS,
(elfcpp::SHF_ALLOC
| elfcpp::SHF_EXECINSTR),
this->plt_, false);
}
this->plt_->add_entry(gsym);
}
// Report an unsupported relocation against a local symbol.
template<bool big_endian>
void
Target_arm<big_endian>::Scan::unsupported_reloc_local(
Sized_relobj<32, big_endian>* object,
unsigned int r_type)
{
gold_error(_("%s: unsupported reloc %u against local symbol"),
object->name().c_str(), r_type);
}
// We are about to emit a dynamic relocation of type R_TYPE. If the
// dynamic linker does not support it, issue an error. The GNU linker
// only issues a non-PIC error for an allocated read-only section.
// Here we know the section is allocated, but we don't know that it is
// read-only. But we check for all the relocation types which the
// glibc dynamic linker supports, so it seems appropriate to issue an
// error even if the section is not read-only.
template<bool big_endian>
void
Target_arm<big_endian>::Scan::check_non_pic(Relobj* object,
unsigned int r_type)
{
switch (r_type)
{
// These are the relocation types supported by glibc for ARM.
case elfcpp::R_ARM_RELATIVE:
case elfcpp::R_ARM_COPY:
case elfcpp::R_ARM_GLOB_DAT:
case elfcpp::R_ARM_JUMP_SLOT:
case elfcpp::R_ARM_ABS32:
case elfcpp::R_ARM_ABS32_NOI:
case elfcpp::R_ARM_PC24:
// FIXME: The following 3 types are not supported by Android's dynamic
// linker.
case elfcpp::R_ARM_TLS_DTPMOD32:
case elfcpp::R_ARM_TLS_DTPOFF32:
case elfcpp::R_ARM_TLS_TPOFF32:
return;
default:
// This prevents us from issuing more than one error per reloc
// section. But we can still wind up issuing more than one
// error per object file.
if (this->issued_non_pic_error_)
return;
object->error(_("requires unsupported dynamic reloc; "
"recompile with -fPIC"));
this->issued_non_pic_error_ = true;
return;
case elfcpp::R_ARM_NONE:
gold_unreachable();
}
}
// Scan a relocation for a local symbol.
// FIXME: This only handles a subset of relocation types used by Android
// on ARM v5te devices.
template<bool big_endian>
inline void
Target_arm<big_endian>::Scan::local(Symbol_table* symtab,
Layout* layout,
Target_arm* target,
Sized_relobj<32, big_endian>* object,
unsigned int data_shndx,
Output_section* output_section,
const elfcpp::Rel<32, big_endian>& reloc,
unsigned int r_type,
const elfcpp::Sym<32, big_endian>&)
{
r_type = get_real_reloc_type(r_type);
switch (r_type)
{
case elfcpp::R_ARM_NONE:
break;
case elfcpp::R_ARM_ABS32:
case elfcpp::R_ARM_ABS32_NOI:
// 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_ARM_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());
// If we are to add more other reloc types than R_ARM_ABS32,
// we need to add check_non_pic(object, r_type) here.
rel_dyn->add_local_relative(object, r_sym, elfcpp::R_ARM_RELATIVE,
output_section, data_shndx,
reloc.get_r_offset());
}
break;
case elfcpp::R_ARM_REL32:
case elfcpp::R_ARM_THM_CALL:
case elfcpp::R_ARM_CALL:
case elfcpp::R_ARM_PREL31:
case elfcpp::R_ARM_JUMP24:
case elfcpp::R_ARM_PLT32:
case elfcpp::R_ARM_THM_ABS5:
case elfcpp::R_ARM_ABS8:
case elfcpp::R_ARM_ABS12:
case elfcpp::R_ARM_ABS16:
case elfcpp::R_ARM_BASE_ABS:
case elfcpp::R_ARM_MOVW_ABS_NC:
case elfcpp::R_ARM_MOVT_ABS:
case elfcpp::R_ARM_THM_MOVW_ABS_NC:
case elfcpp::R_ARM_THM_MOVT_ABS:
case elfcpp::R_ARM_MOVW_PREL_NC:
case elfcpp::R_ARM_MOVT_PREL:
case elfcpp::R_ARM_THM_MOVW_PREL_NC:
case elfcpp::R_ARM_THM_MOVT_PREL:
break;
case elfcpp::R_ARM_GOTOFF32:
// We need a GOT section:
target->got_section(symtab, layout);
break;
case elfcpp::R_ARM_BASE_PREL:
// FIXME: What about this?
break;
case elfcpp::R_ARM_GOT_BREL:
case elfcpp::R_ARM_GOT_PREL:
{
// The symbol requires a GOT entry.
Output_data_got<32, big_endian>* 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_ARM_RELATIVE, got,
object->local_got_offset(r_sym, GOT_TYPE_STANDARD));
}
}
}
break;
case elfcpp::R_ARM_TARGET1:
// This should have been mapped to another type already.
// Fall through.
case elfcpp::R_ARM_COPY:
case elfcpp::R_ARM_GLOB_DAT:
case elfcpp::R_ARM_JUMP_SLOT:
case elfcpp::R_ARM_RELATIVE:
// These are relocations which should only be seen by the
// dynamic linker, and should never be seen here.
gold_error(_("%s: unexpected reloc %u in object file"),
object->name().c_str(), r_type);
break;
default:
unsupported_reloc_local(object, r_type);
break;
}
}
// Report an unsupported relocation against a global symbol.
template<bool big_endian>
void
Target_arm<big_endian>::Scan::unsupported_reloc_global(
Sized_relobj<32, big_endian>* 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());
}
// Scan a relocation for a global symbol.
// FIXME: This only handles a subset of relocation types used by Android
// on ARM v5te devices.
template<bool big_endian>
inline void
Target_arm<big_endian>::Scan::global(Symbol_table* symtab,
Layout* layout,
Target_arm* target,
Sized_relobj<32, big_endian>* object,
unsigned int data_shndx,
Output_section* output_section,
const elfcpp::Rel<32, big_endian>& reloc,
unsigned int r_type,
Symbol* gsym)
{
r_type = get_real_reloc_type(r_type);
switch (r_type)
{
case elfcpp::R_ARM_NONE:
break;
case elfcpp::R_ARM_ABS32:
case elfcpp::R_ARM_ABS32_NOI:
{
// Make a dynamic relocation if necessary.
if (gsym->needs_dynamic_reloc(Symbol::ABSOLUTE_REF))
{
if (target->may_need_copy_reloc(gsym))
{
target->copy_reloc(symtab, layout, object,
data_shndx, output_section, gsym, reloc);
}
else if (gsym->can_use_relative_reloc(false))
{
// If we are to add more other reloc types than R_ARM_ABS32,
// we need to add check_non_pic(object, r_type) here.
Reloc_section* rel_dyn = target->rel_dyn_section(layout);
rel_dyn->add_global_relative(gsym, elfcpp::R_ARM_RELATIVE,
output_section, object,
data_shndx, reloc.get_r_offset());
}
else
{
// If we are to add more other reloc types than R_ARM_ABS32,
// we need to add check_non_pic(object, r_type) here.
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_ARM_MOVW_ABS_NC:
case elfcpp::R_ARM_MOVT_ABS:
case elfcpp::R_ARM_THM_MOVW_ABS_NC:
case elfcpp::R_ARM_THM_MOVT_ABS:
case elfcpp::R_ARM_MOVW_PREL_NC:
case elfcpp::R_ARM_MOVT_PREL:
case elfcpp::R_ARM_THM_MOVW_PREL_NC:
case elfcpp::R_ARM_THM_MOVT_PREL:
break;
case elfcpp::R_ARM_THM_ABS5:
case elfcpp::R_ARM_ABS8:
case elfcpp::R_ARM_ABS12:
case elfcpp::R_ARM_ABS16:
case elfcpp::R_ARM_BASE_ABS:
{
// No dynamic relocs of this kinds.
// Report the error in case of PIC.
int flags = Symbol::NON_PIC_REF;
if (gsym->type() == elfcpp::STT_FUNC
|| gsym->type() == elfcpp::STT_ARM_TFUNC)
flags |= Symbol::FUNCTION_CALL;
if (gsym->needs_dynamic_reloc(flags))
check_non_pic(object, r_type);
}
break;
case elfcpp::R_ARM_REL32:
case elfcpp::R_ARM_PREL31:
{
// Make a dynamic relocation if necessary.
int flags = Symbol::NON_PIC_REF;
if (gsym->needs_dynamic_reloc(flags))
{
if (target->may_need_copy_reloc(gsym))
{
target->copy_reloc(symtab, layout, object,
data_shndx, output_section, gsym, reloc);
}
else
{
check_non_pic(object, r_type);
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_ARM_JUMP24:
case elfcpp::R_ARM_THM_CALL:
case elfcpp::R_ARM_CALL:
{
if (Target_arm<big_endian>::Scan::symbol_needs_plt_entry(gsym))
target->make_plt_entry(symtab, layout, gsym);
// Make a dynamic relocation if necessary.
int flags = Symbol::NON_PIC_REF;
if (gsym->type() == elfcpp::STT_FUNC
|| gsym->type() == elfcpp::STT_ARM_TFUNC)
flags |= Symbol::FUNCTION_CALL;
if (gsym->needs_dynamic_reloc(flags))
{
if (target->may_need_copy_reloc(gsym))
{
target->copy_reloc(symtab, layout, object,
data_shndx, output_section, gsym,
reloc);
}
else
{
check_non_pic(object, r_type);
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_ARM_PLT32:
// If the symbol is fully resolved, this is just a relative
// local 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_ARM_GOTOFF32:
// We need a GOT section.
target->got_section(symtab, layout);
break;
case elfcpp::R_ARM_BASE_PREL:
// FIXME: What about this?
break;
case elfcpp::R_ARM_GOT_BREL:
case elfcpp::R_ARM_GOT_PREL:
{
// The symbol requires a GOT entry.
Output_data_got<32, big_endian>* 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_ARM_GLOB_DAT);
else
{
if (got->add_global(gsym, GOT_TYPE_STANDARD))
rel_dyn->add_global_relative(
gsym, elfcpp::R_ARM_RELATIVE, got,
gsym->got_offset(GOT_TYPE_STANDARD));
}
}
}
break;
case elfcpp::R_ARM_TARGET1:
// This should have been mapped to another type already.
// Fall through.
case elfcpp::R_ARM_COPY:
case elfcpp::R_ARM_GLOB_DAT:
case elfcpp::R_ARM_JUMP_SLOT:
case elfcpp::R_ARM_RELATIVE:
// These are relocations which should only be seen by the
// dynamic linker, and should never be seen here.
gold_error(_("%s: unexpected reloc %u in object file"),
object->name().c_str(), r_type);
break;
default:
unsupported_reloc_global(object, r_type, gsym);
break;
}
}
// Process relocations for gc.
template<bool big_endian>
void
Target_arm<big_endian>::gc_process_relocs(Symbol_table* symtab,
Layout* layout,
Sized_relobj<32, big_endian>* 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)
{
typedef Target_arm<big_endian> Arm;
typedef typename Target_arm<big_endian>::Scan Scan;
gold::gc_process_relocs<32, big_endian, Arm, elfcpp::SHT_REL, Scan>(
symtab,
layout,
this,
object,
data_shndx,
prelocs,
reloc_count,
output_section,
needs_special_offset_handling,
local_symbol_count,
plocal_symbols);
}
// Scan relocations for a section.
template<bool big_endian>
void
Target_arm<big_endian>::scan_relocs(Symbol_table* symtab,
Layout* layout,
Sized_relobj<32, big_endian>* object,
unsigned int data_shndx,
unsigned int sh_type,
const unsigned char* prelocs,
size_t reloc_count,
Output_section* output_section,
bool needs_special_offset_handling,
size_t local_symbol_count,
const unsigned char* plocal_symbols)
{
typedef typename Target_arm<big_endian>::Scan Scan;
if (sh_type == elfcpp::SHT_RELA)
{
gold_error(_("%s: unsupported RELA reloc section"),
object->name().c_str());
return;
}
gold::scan_relocs<32, big_endian, Target_arm, elfcpp::SHT_REL, Scan>(
symtab,
layout,
this,
object,
data_shndx,
prelocs,
reloc_count,
output_section,
needs_special_offset_handling,
local_symbol_count,
plocal_symbols);
}
// Finalize the sections.
template<bool big_endian>
void
Target_arm<big_endian>::do_finalize_sections(
Layout* layout,
const Input_objects* input_objects)
{
// Merge processor-specific flags.
for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
p != input_objects->relobj_end();
++p)
{
Arm_relobj<big_endian>* arm_relobj =
Arm_relobj<big_endian>::as_arm_relobj(*p);
this->merge_processor_specific_flags(
arm_relobj->name(),
arm_relobj->processor_specific_flags());
}
for (Input_objects::Dynobj_iterator p = input_objects->dynobj_begin();
p != input_objects->dynobj_end();
++p)
{
Arm_dynobj<big_endian>* arm_dynobj =
Arm_dynobj<big_endian>::as_arm_dynobj(*p);
this->merge_processor_specific_flags(
arm_dynobj->name(),
arm_dynobj->processor_specific_flags());
}
// Fill in some more dynamic tags.
Output_data_dynamic* const odyn = layout->dynamic_data();
if (odyn != NULL)
{
if (this->got_plt_ != NULL
&& this->got_plt_->output_section() != NULL)
odyn->add_section_address(elfcpp::DT_PLTGOT, this->got_plt_);
if (this->plt_ != NULL
&& this->plt_->output_section() != NULL)
{
const Output_data* od = this->plt_->rel_plt();
odyn->add_section_size(elfcpp::DT_PLTRELSZ, od);
odyn->add_section_address(elfcpp::DT_JMPREL, od);
odyn->add_constant(elfcpp::DT_PLTREL, elfcpp::DT_REL);
}
if (this->rel_dyn_ != NULL
&& this->rel_dyn_->output_section() != NULL)
{
const Output_data* od = this->rel_dyn_;
odyn->add_section_address(elfcpp::DT_REL, od);
odyn->add_section_size(elfcpp::DT_RELSZ, od);
odyn->add_constant(elfcpp::DT_RELENT,
elfcpp::Elf_sizes<32>::rel_size);
}
if (!parameters->options().shared())
{
// The value of the DT_DEBUG tag is filled in by the dynamic
// linker at run time, and used by the debugger.
odyn->add_constant(elfcpp::DT_DEBUG, 0);
}
}
// 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));
// For the ARM target, we need to add a PT_ARM_EXIDX segment for
// the .ARM.exidx section.
if (!layout->script_options()->saw_phdrs_clause()
&& !parameters->options().relocatable())
{
Output_section* exidx_section =
layout->find_output_section(".ARM.exidx");
if (exidx_section != NULL
&& exidx_section->type() == elfcpp::SHT_ARM_EXIDX)
{
gold_assert(layout->find_output_segment(elfcpp::PT_ARM_EXIDX, 0, 0)
== NULL);
Output_segment* exidx_segment =
layout->make_output_segment(elfcpp::PT_ARM_EXIDX, elfcpp::PF_R);
exidx_segment->add_output_section(exidx_section, elfcpp::PF_R,
false);
}
}
}
// 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_ARM_RELATIVE, the addend
// of the relocation is carried in the data, and we must not
// apply the static relocation.
template<bool big_endian>
inline bool
Target_arm<big_endian>::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.
template<bool big_endian>
inline bool
Target_arm<big_endian>::Relocate::relocate(
const Relocate_info<32, big_endian>* relinfo,
Target_arm* target,
Output_section *output_section,
size_t relnum,
const elfcpp::Rel<32, big_endian>& rel,
unsigned int r_type,
const Sized_symbol<32>* gsym,
const Symbol_value<32>* psymval,
unsigned char* view,
Arm_address address,
section_size_type /* view_size */ )
{
typedef Arm_relocate_functions<big_endian> Arm_relocate_functions;
r_type = get_real_reloc_type(r_type);
const Arm_relobj<big_endian>* object =
Arm_relobj<big_endian>::as_arm_relobj(relinfo->object);
// If the final branch target of a relocation is THUMB instruction, this
// is 1. Otherwise it is 0.
Arm_address thumb_bit = 0;
Symbol_value<32> symval;
bool is_weakly_undefined_without_plt = false;
if (relnum != Target_arm<big_endian>::fake_relnum_for_stubs)
{
if (gsym != NULL)
{
// This is a global symbol. Determine if we use PLT and if the
// final target is THUMB.
if (gsym->use_plt_offset(reloc_is_non_pic(r_type)))
{
// This uses a PLT, change the symbol value.
symval.set_output_value(target->plt_section()->address()
+ gsym->plt_offset());
psymval = &symval;
}
else if (gsym->is_weak_undefined())
{
// This is a weakly undefined symbol and we do not use PLT
// for this relocation. A branch targeting this symbol will
// be converted into an NOP.
is_weakly_undefined_without_plt = true;
}
else
{
// Set thumb bit if symbol:
// -Has type STT_ARM_TFUNC or
// -Has type STT_FUNC, is defined and with LSB in value set.
thumb_bit =
(((gsym->type() == elfcpp::STT_ARM_TFUNC)
|| (gsym->type() == elfcpp::STT_FUNC
&& !gsym->is_undefined()
&& ((psymval->value(object, 0) & 1) != 0)))
? 1
: 0);
}
}
else
{
// This is a local symbol. Determine if the final target is THUMB.
// We saved this information when all the local symbols were read.
elfcpp::Elf_types<32>::Elf_WXword r_info = rel.get_r_info();
unsigned int r_sym = elfcpp::elf_r_sym<32>(r_info);
thumb_bit = object->local_symbol_is_thumb_function(r_sym) ? 1 : 0;
}
}
else
{
// This is a fake relocation synthesized for a stub. It does not have
// a real symbol. We just look at the LSB of the symbol value to
// determine if the target is THUMB or not.
thumb_bit = ((psymval->value(object, 0) & 1) != 0);
}
// Strip LSB if this points to a THUMB target.
if (thumb_bit != 0
&& Target_arm<big_endian>::reloc_uses_thumb_bit(r_type)
&& ((psymval->value(object, 0) & 1) != 0))
{
Arm_address stripped_value =
psymval->value(object, 0) & ~static_cast<Arm_address>(1);
symval.set_output_value(stripped_value);
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_ARM_GOT_BREL:
case elfcpp::R_ARM_GOT_PREL:
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;
}
// To look up relocation stubs, we need to pass the symbol table index of
// a local symbol.
unsigned int r_sym = elfcpp::elf_r_sym<32>(rel.get_r_info());
typename Arm_relocate_functions::Status reloc_status =
Arm_relocate_functions::STATUS_OKAY;
switch (r_type)
{
case elfcpp::R_ARM_NONE:
break;
case elfcpp::R_ARM_ABS8:
if (should_apply_static_reloc(gsym, Symbol::ABSOLUTE_REF, false,
output_section))
reloc_status = Arm_relocate_functions::abs8(view, object, psymval);
break;
case elfcpp::R_ARM_ABS12:
if (should_apply_static_reloc(gsym, Symbol::ABSOLUTE_REF, false,
output_section))
reloc_status = Arm_relocate_functions::abs12(view, object, psymval);
break;
case elfcpp::R_ARM_ABS16:
if (should_apply_static_reloc(gsym, Symbol::ABSOLUTE_REF, false,
output_section))
reloc_status = Arm_relocate_functions::abs16(view, object, psymval);
break;
case elfcpp::R_ARM_ABS32:
if (should_apply_static_reloc(gsym, Symbol::ABSOLUTE_REF, true,
output_section))
reloc_status = Arm_relocate_functions::abs32(view, object, psymval,
thumb_bit);
break;
case elfcpp::R_ARM_ABS32_NOI:
if (should_apply_static_reloc(gsym, Symbol::ABSOLUTE_REF, true,
output_section))
// No thumb bit for this relocation: (S + A)
reloc_status = Arm_relocate_functions::abs32(view, object, psymval,
false);
break;
case elfcpp::R_ARM_MOVW_ABS_NC:
if (should_apply_static_reloc(gsym, Symbol::ABSOLUTE_REF, true,
output_section))
reloc_status = Arm_relocate_functions::movw_abs_nc(view, object,
psymval,
thumb_bit);
else
gold_error(_("relocation R_ARM_MOVW_ABS_NC cannot be used when making"
"a shared object; recompile with -fPIC"));
break;
case elfcpp::R_ARM_MOVT_ABS:
if (should_apply_static_reloc(gsym, Symbol::ABSOLUTE_REF, true,
output_section))
reloc_status = Arm_relocate_functions::movt_abs(view, object, psymval);
else
gold_error(_("relocation R_ARM_MOVT_ABS cannot be used when making"
"a shared object; recompile with -fPIC"));
break;
case elfcpp::R_ARM_THM_MOVW_ABS_NC:
if (should_apply_static_reloc(gsym, Symbol::ABSOLUTE_REF, true,
output_section))
reloc_status = Arm_relocate_functions::thm_movw_abs_nc(view, object,
psymval,
thumb_bit);
else
gold_error(_("relocation R_ARM_THM_MOVW_ABS_NC cannot be used when"
"making a shared object; recompile with -fPIC"));
break;
case elfcpp::R_ARM_THM_MOVT_ABS:
if (should_apply_static_reloc(gsym, Symbol::ABSOLUTE_REF, true,
output_section))
reloc_status = Arm_relocate_functions::thm_movt_abs(view, object,
psymval);
else
gold_error(_("relocation R_ARM_THM_MOVT_ABS cannot be used when"
"making a shared object; recompile with -fPIC"));
break;
case elfcpp::R_ARM_MOVW_PREL_NC:
reloc_status = Arm_relocate_functions::movw_prel_nc(view, object,
psymval, address,
thumb_bit);
break;
case elfcpp::R_ARM_MOVT_PREL:
reloc_status = Arm_relocate_functions::movt_prel(view, object,
psymval, address);
break;
case elfcpp::R_ARM_THM_MOVW_PREL_NC:
reloc_status = Arm_relocate_functions::thm_movw_prel_nc(view, object,
psymval, address,
thumb_bit);
break;
case elfcpp::R_ARM_THM_MOVT_PREL:
reloc_status = Arm_relocate_functions::thm_movt_prel(view, object,
psymval, address);
break;
case elfcpp::R_ARM_REL32:
reloc_status = Arm_relocate_functions::rel32(view, object, psymval,
address, thumb_bit);
break;
case elfcpp::R_ARM_THM_ABS5:
if (should_apply_static_reloc(gsym, Symbol::ABSOLUTE_REF, false,
output_section))
reloc_status = Arm_relocate_functions::thm_abs5(view, object, psymval);
break;
case elfcpp::R_ARM_THM_CALL:
reloc_status =
Arm_relocate_functions::thm_call(relinfo, view, gsym, object, r_sym,
psymval, address, thumb_bit,
is_weakly_undefined_without_plt);
break;
case elfcpp::R_ARM_XPC25:
reloc_status =
Arm_relocate_functions::xpc25(relinfo, view, gsym, object, r_sym,
psymval, address, thumb_bit,
is_weakly_undefined_without_plt);
break;
case elfcpp::R_ARM_THM_XPC22:
reloc_status =
Arm_relocate_functions::thm_xpc22(relinfo, view, gsym, object, r_sym,
psymval, address, thumb_bit,
is_weakly_undefined_without_plt);
break;
case elfcpp::R_ARM_GOTOFF32:
{
Arm_address got_origin;
got_origin = target->got_plt_section()->address();
reloc_status = Arm_relocate_functions::rel32(view, object, psymval,
got_origin, thumb_bit);
}
break;
case elfcpp::R_ARM_BASE_PREL:
{
uint32_t origin;
// Get the addressing origin of the output segment defining the
// symbol gsym (AAELF 4.6.1.2 Relocation types)
gold_assert(gsym != NULL);
if (gsym->source() == Symbol::IN_OUTPUT_SEGMENT)
origin = gsym->output_segment()->vaddr();
else if (gsym->source () == Symbol::IN_OUTPUT_DATA)
origin = gsym->output_data()->address();
else
{
gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
_("cannot find origin of R_ARM_BASE_PREL"));
return true;
}
reloc_status = Arm_relocate_functions::base_prel(view, origin, address);
}
break;
case elfcpp::R_ARM_BASE_ABS:
{
if (!should_apply_static_reloc(gsym, Symbol::ABSOLUTE_REF, true,
output_section))
break;
uint32_t origin;
// Get the addressing origin of the output segment defining
// the symbol gsym (AAELF 4.6.1.2 Relocation types).
if (gsym == NULL)
// R_ARM_BASE_ABS with the NULL symbol will give the
// absolute address of the GOT origin (GOT_ORG) (see ARM IHI
// 0044C (AAELF): 4.6.1.8 Proxy generating relocations).
origin = target->got_plt_section()->address();
else if (gsym->source() == Symbol::IN_OUTPUT_SEGMENT)
origin = gsym->output_segment()->vaddr();
else if (gsym->source () == Symbol::IN_OUTPUT_DATA)
origin = gsym->output_data()->address();
else
{
gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
_("cannot find origin of R_ARM_BASE_ABS"));
return true;
}
reloc_status = Arm_relocate_functions::base_abs(view, origin);
}
break;
case elfcpp::R_ARM_GOT_BREL:
gold_assert(have_got_offset);
reloc_status = Arm_relocate_functions::got_brel(view, got_offset);
break;
case elfcpp::R_ARM_GOT_PREL:
gold_assert(have_got_offset);
// Get the address origin for GOT PLT, which is allocated right
// after the GOT section, to calculate an absolute address of
// the symbol GOT entry (got_origin + got_offset).
Arm_address got_origin;
got_origin = target->got_plt_section()->address();
reloc_status = Arm_relocate_functions::got_prel(view,
got_origin + got_offset,
address);
break;
case elfcpp::R_ARM_PLT32:
gold_assert(gsym == NULL
|| gsym->has_plt_offset()
|| gsym->final_value_is_known()
|| (gsym->is_defined()
&& !gsym->is_from_dynobj()
&& !gsym->is_preemptible()));
reloc_status =
Arm_relocate_functions::plt32(relinfo, view, gsym, object, r_sym,
psymval, address, thumb_bit,
is_weakly_undefined_without_plt);
break;
case elfcpp::R_ARM_CALL:
reloc_status =
Arm_relocate_functions::call(relinfo, view, gsym, object, r_sym,
psymval, address, thumb_bit,
is_weakly_undefined_without_plt);
break;
case elfcpp::R_ARM_JUMP24:
reloc_status =
Arm_relocate_functions::jump24(relinfo, view, gsym, object, r_sym,
psymval, address, thumb_bit,
is_weakly_undefined_without_plt);
break;
case elfcpp::R_ARM_THM_JUMP24:
reloc_status =
Arm_relocate_functions::thm_jump24(relinfo, view, gsym, object, r_sym,
psymval, address, thumb_bit,
is_weakly_undefined_without_plt);
break;
case elfcpp::R_ARM_PREL31:
reloc_status = Arm_relocate_functions::prel31(view, object, psymval,
address, thumb_bit);
break;
case elfcpp::R_ARM_TARGET1:
// This should have been mapped to another type already.
// Fall through.
case elfcpp::R_ARM_COPY:
case elfcpp::R_ARM_GLOB_DAT:
case elfcpp::R_ARM_JUMP_SLOT:
case elfcpp::R_ARM_RELATIVE:
// These are relocations which should only be seen by the
// dynamic linker, and should never be seen here.
gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
_("unexpected reloc %u in object file"),
r_type);
break;
default:
gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
_("unsupported reloc %u"),
r_type);
break;
}
// Report any errors.
switch (reloc_status)
{
case Arm_relocate_functions::STATUS_OKAY:
break;
case Arm_relocate_functions::STATUS_OVERFLOW:
gold_error_at_location(relinfo, relnum, rel.get_r_offset(),
_("relocation overflow in relocation %u"),
r_type);
break;
case Arm_relocate_functions::STATUS_BAD_RELOC:
gold_error_at_location(
relinfo,
relnum,
rel.get_r_offset(),
_("unexpected opcode while processing relocation %u"),
r_type);
break;
default:
gold_unreachable();
}
return true;
}
// Relocate section data.
template<bool big_endian>
void
Target_arm<big_endian>::relocate_section(
const Relocate_info<32, big_endian>* 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,
Arm_address address,
section_size_type view_size,
const Reloc_symbol_changes* reloc_symbol_changes)
{
typedef typename Target_arm<big_endian>::Relocate Arm_relocate;
gold_assert(sh_type == elfcpp::SHT_REL);
Arm_input_section<big_endian>* arm_input_section =
this->find_arm_input_section(relinfo->object, relinfo->data_shndx);
// This is an ARM input section and the view covers the whole output
// section.
if (arm_input_section != NULL)
{
gold_assert(needs_special_offset_handling);
Arm_address section_address = arm_input_section->address();
section_size_type section_size = arm_input_section->data_size();
gold_assert((arm_input_section->address() >= address)
&& ((arm_input_section->address()
+ arm_input_section->data_size())
<= (address + view_size)));
off_t offset = section_address - address;
view += offset;
address += offset;
view_size = section_size;
}
gold::relocate_section<32, big_endian, Target_arm, elfcpp::SHT_REL,
Arm_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.
template<bool big_endian>
unsigned int
Target_arm<big_endian>::Relocatable_size_for_reloc::get_size_for_reloc(
unsigned int r_type,
Relobj* object)
{
r_type = get_real_reloc_type(r_type);
switch (r_type)
{
case elfcpp::R_ARM_NONE:
return 0;
case elfcpp::R_ARM_ABS8:
return 1;
case elfcpp::R_ARM_ABS16:
case elfcpp::R_ARM_THM_ABS5:
return 2;
case elfcpp::R_ARM_ABS32:
case elfcpp::R_ARM_ABS32_NOI:
case elfcpp::R_ARM_ABS12:
case elfcpp::R_ARM_BASE_ABS:
case elfcpp::R_ARM_REL32:
case elfcpp::R_ARM_THM_CALL:
case elfcpp::R_ARM_GOTOFF32:
case elfcpp::R_ARM_BASE_PREL:
case elfcpp::R_ARM_GOT_BREL:
case elfcpp::R_ARM_GOT_PREL:
case elfcpp::R_ARM_PLT32:
case elfcpp::R_ARM_CALL:
case elfcpp::R_ARM_JUMP24:
case elfcpp::R_ARM_PREL31:
case elfcpp::R_ARM_MOVW_ABS_NC:
case elfcpp::R_ARM_MOVT_ABS:
case elfcpp::R_ARM_THM_MOVW_ABS_NC:
case elfcpp::R_ARM_THM_MOVT_ABS:
case elfcpp::R_ARM_MOVW_PREL_NC:
case elfcpp::R_ARM_MOVT_PREL:
case elfcpp::R_ARM_THM_MOVW_PREL_NC:
case elfcpp::R_ARM_THM_MOVT_PREL:
return 4;
case elfcpp::R_ARM_TARGET1:
// This should have been mapped to another type already.
// Fall through.
case elfcpp::R_ARM_COPY:
case elfcpp::R_ARM_GLOB_DAT:
case elfcpp::R_ARM_JUMP_SLOT:
case elfcpp::R_ARM_RELATIVE:
// These are relocations which should only be seen by the
// dynamic linker, and should never be seen here.
gold_error(_("%s: unexpected reloc %u in object file"),
object->name().c_str(), r_type);
return 0;
default:
object->error(_("unsupported reloc %u in object file"), r_type);
return 0;
}
}
// Scan the relocs during a relocatable link.
template<bool big_endian>
void
Target_arm<big_endian>::scan_relocatable_relocs(
Symbol_table* symtab,
Layout* layout,
Sized_relobj<32, big_endian>* object,
unsigned int data_shndx,
unsigned int sh_type,
const unsigned char* prelocs,
size_t reloc_count,
Output_section* output_section,
bool needs_special_offset_handling,
size_t local_symbol_count,
const unsigned char* plocal_symbols,
Relocatable_relocs* 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, big_endian, 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.
template<bool big_endian>
void
Target_arm<big_endian>::relocate_for_relocatable(
const Relocate_info<32, big_endian>* 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,
Arm_address 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, big_endian, 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 symbol which requires special
// treatment. This is how we support equality comparisons of function
// pointers across shared library boundaries, as described in the
// processor specific ABI supplement.
template<bool big_endian>
uint64_t
Target_arm<big_endian>::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();
}
// Map platform-specific relocs to real relocs
//
template<bool big_endian>
unsigned int
Target_arm<big_endian>::get_real_reloc_type (unsigned int r_type)
{
switch (r_type)
{
case elfcpp::R_ARM_TARGET1:
// This is either R_ARM_ABS32 or R_ARM_REL32;
return elfcpp::R_ARM_ABS32;
case elfcpp::R_ARM_TARGET2:
// This can be any reloc type but ususally is R_ARM_GOT_PREL
return elfcpp::R_ARM_GOT_PREL;
default:
return r_type;
}
}
// Whether if two EABI versions V1 and V2 are compatible.
template<bool big_endian>
bool
Target_arm<big_endian>::are_eabi_versions_compatible(
elfcpp::Elf_Word v1,
elfcpp::Elf_Word v2)
{
// v4 and v5 are the same spec before and after it was released,
// so allow mixing them.
if ((v1 == elfcpp::EF_ARM_EABI_VER4 && v2 == elfcpp::EF_ARM_EABI_VER5)
|| (v1 == elfcpp::EF_ARM_EABI_VER5 && v2 == elfcpp::EF_ARM_EABI_VER4))
return true;
return v1 == v2;
}
// Combine FLAGS from an input object called NAME and the processor-specific
// flags in the ELF header of the output. Much of this is adapted from the
// processor-specific flags merging code in elf32_arm_merge_private_bfd_data
// in bfd/elf32-arm.c.
template<bool big_endian>
void
Target_arm<big_endian>::merge_processor_specific_flags(
const std::string& name,
elfcpp::Elf_Word flags)
{
if (this->are_processor_specific_flags_set())
{
elfcpp::Elf_Word out_flags = this->processor_specific_flags();
// Nothing to merge if flags equal to those in output.
if (flags == out_flags)
return;
// Complain about various flag mismatches.
elfcpp::Elf_Word version1 = elfcpp::arm_eabi_version(flags);
elfcpp::Elf_Word version2 = elfcpp::arm_eabi_version(out_flags);
if (!this->are_eabi_versions_compatible(version1, version2))
gold_error(_("Source object %s has EABI version %d but output has "
"EABI version %d."),
name.c_str(),
(flags & elfcpp::EF_ARM_EABIMASK) >> 24,
(out_flags & elfcpp::EF_ARM_EABIMASK) >> 24);
}
else
{
// If the input is the default architecture and had the default
// flags then do not bother setting the flags for the output
// architecture, instead allow future merges to do this. If no
// future merges ever set these flags then they will retain their
// uninitialised values, which surprise surprise, correspond
// to the default values.
if (flags == 0)
return;
// This is the first time, just copy the flags.
// We only copy the EABI version for now.
this->set_processor_specific_flags(flags & elfcpp::EF_ARM_EABIMASK);
}
}
// Adjust ELF file header.
template<bool big_endian>
void
Target_arm<big_endian>::do_adjust_elf_header(
unsigned char* view,
int len) const
{
gold_assert(len == elfcpp::Elf_sizes<32>::ehdr_size);
elfcpp::Ehdr<32, big_endian> ehdr(view);
unsigned char e_ident[elfcpp::EI_NIDENT];
memcpy(e_ident, ehdr.get_e_ident(), elfcpp::EI_NIDENT);
if (elfcpp::arm_eabi_version(this->processor_specific_flags())
== elfcpp::EF_ARM_EABI_UNKNOWN)
e_ident[elfcpp::EI_OSABI] = elfcpp::ELFOSABI_ARM;
else
e_ident[elfcpp::EI_OSABI] = 0;
e_ident[elfcpp::EI_ABIVERSION] = 0;
// FIXME: Do EF_ARM_BE8 adjustment.
elfcpp::Ehdr_write<32, big_endian> oehdr(view);
oehdr.put_e_ident(e_ident);
}
// do_make_elf_object to override the same function in the base class.
// We need to use a target-specific sub-class of Sized_relobj<32, big_endian>
// to store ARM specific information. Hence we need to have our own
// ELF object creation.
template<bool big_endian>
Object*
Target_arm<big_endian>::do_make_elf_object(
const std::string& name,
Input_file* input_file,
off_t offset, const elfcpp::Ehdr<32, big_endian>& ehdr)
{
int et = ehdr.get_e_type();
if (et == elfcpp::ET_REL)
{
Arm_relobj<big_endian>* obj =
new Arm_relobj<big_endian>(name, input_file, offset, ehdr);
obj->setup();
return obj;
}
else if (et == elfcpp::ET_DYN)
{
Sized_dynobj<32, big_endian>* obj =
new Arm_dynobj<big_endian>(name, input_file, offset, ehdr);
obj->setup();
return obj;
}
else
{
gold_error(_("%s: unsupported ELF file type %d"),
name.c_str(), et);
return NULL;
}
}
// Return whether a relocation type used the LSB to distinguish THUMB
// addresses.
template<bool big_endian>
bool
Target_arm<big_endian>::reloc_uses_thumb_bit(unsigned int r_type)
{
switch (r_type)
{
case elfcpp::R_ARM_PC24:
case elfcpp::R_ARM_ABS32:
case elfcpp::R_ARM_REL32:
case elfcpp::R_ARM_SBREL32:
case elfcpp::R_ARM_THM_CALL:
case elfcpp::R_ARM_GLOB_DAT:
case elfcpp::R_ARM_JUMP_SLOT:
case elfcpp::R_ARM_GOTOFF32:
case elfcpp::R_ARM_PLT32:
case elfcpp::R_ARM_CALL:
case elfcpp::R_ARM_JUMP24:
case elfcpp::R_ARM_THM_JUMP24:
case elfcpp::R_ARM_SBREL31:
case elfcpp::R_ARM_PREL31:
case elfcpp::R_ARM_MOVW_ABS_NC:
case elfcpp::R_ARM_MOVW_PREL_NC:
case elfcpp::R_ARM_THM_MOVW_ABS_NC:
case elfcpp::R_ARM_THM_MOVW_PREL_NC:
case elfcpp::R_ARM_THM_JUMP19:
case elfcpp::R_ARM_THM_ALU_PREL_11_0:
case elfcpp::R_ARM_ALU_PC_G0_NC:
case elfcpp::R_ARM_ALU_PC_G0:
case elfcpp::R_ARM_ALU_PC_G1_NC:
case elfcpp::R_ARM_ALU_PC_G1:
case elfcpp::R_ARM_ALU_PC_G2:
case elfcpp::R_ARM_ALU_SB_G0_NC:
case elfcpp::R_ARM_ALU_SB_G0:
case elfcpp::R_ARM_ALU_SB_G1_NC:
case elfcpp::R_ARM_ALU_SB_G1:
case elfcpp::R_ARM_ALU_SB_G2:
case elfcpp::R_ARM_MOVW_BREL_NC:
case elfcpp::R_ARM_MOVW_BREL:
case elfcpp::R_ARM_THM_MOVW_BREL_NC:
case elfcpp::R_ARM_THM_MOVW_BREL:
return true;
default:
return false;
}
}
// Stub-generation methods for Target_arm.
// Make a new Arm_input_section object.
template<bool big_endian>
Arm_input_section<big_endian>*
Target_arm<big_endian>::new_arm_input_section(
Relobj* relobj,
unsigned int shndx)
{
Input_section_specifier iss(relobj, shndx);
Arm_input_section<big_endian>* arm_input_section =
new Arm_input_section<big_endian>(relobj, shndx);
arm_input_section->init();
// Register new Arm_input_section in map for look-up.
std::pair<typename Arm_input_section_map::iterator, bool> ins =
this->arm_input_section_map_.insert(std::make_pair(iss, arm_input_section));
// Make sure that it we have not created another Arm_input_section
// for this input section already.
gold_assert(ins.second);
return arm_input_section;
}
// Find the Arm_input_section object corresponding to the SHNDX-th input
// section of RELOBJ.
template<bool big_endian>
Arm_input_section<big_endian>*
Target_arm<big_endian>::find_arm_input_section(
Relobj* relobj,
unsigned int shndx) const
{
Input_section_specifier iss(relobj, shndx);
typename Arm_input_section_map::const_iterator p =
this->arm_input_section_map_.find(iss);
return (p != this->arm_input_section_map_.end()) ? p->second : NULL;
}
// Make a new stub table.
template<bool big_endian>
Stub_table<big_endian>*
Target_arm<big_endian>::new_stub_table(Arm_input_section<big_endian>* owner)
{
Stub_table<big_endian>* stub_table =
new Stub_table<big_endian>(owner);
this->stub_tables_.push_back(stub_table);
stub_table->set_address(owner->address() + owner->data_size());
stub_table->set_file_offset(owner->offset() + owner->data_size());
stub_table->finalize_data_size();
return stub_table;
}
// Scan a relocation for stub generation.
template<bool big_endian>
void
Target_arm<big_endian>::scan_reloc_for_stub(
const Relocate_info<32, big_endian>* relinfo,
unsigned int r_type,
const Sized_symbol<32>* gsym,
unsigned int r_sym,
const Symbol_value<32>* psymval,
elfcpp::Elf_types<32>::Elf_Swxword addend,
Arm_address address)
{
typedef typename Target_arm<big_endian>::Relocate Relocate;
const Arm_relobj<big_endian>* arm_relobj =
Arm_relobj<big_endian>::as_arm_relobj(relinfo->object);
bool target_is_thumb;
Symbol_value<32> symval;
if (gsym != NULL)
{
// This is a global symbol. Determine if we use PLT and if the
// final target is THUMB.
if (gsym->use_plt_offset(Relocate::reloc_is_non_pic(r_type)))
{
// This uses a PLT, change the symbol value.
symval.set_output_value(this->plt_section()->address()
+ gsym->plt_offset());
psymval = &symval;
target_is_thumb = false;
}
else if (gsym->is_undefined())
// There is no need to generate a stub symbol is undefined.
return;
else
{
target_is_thumb =
((gsym->type() == elfcpp::STT_ARM_TFUNC)
|| (gsym->type() == elfcpp::STT_FUNC
&& !gsym->is_undefined()
&& ((psymval->value(arm_relobj, 0) & 1) != 0)));
}
}
else
{
// This is a local symbol. Determine if the final target is THUMB.
target_is_thumb = arm_relobj->local_symbol_is_thumb_function(r_sym);
}
// Strip LSB if this points to a THUMB target.
if (target_is_thumb
&& Target_arm<big_endian>::reloc_uses_thumb_bit(r_type)
&& ((psymval->value(arm_relobj, 0) & 1) != 0))
{
Arm_address stripped_value =
psymval->value(arm_relobj, 0) & ~static_cast<Arm_address>(1);
symval.set_output_value(stripped_value);
psymval = &symval;
}
// Get the symbol value.
Symbol_value<32>::Value value = psymval->value(arm_relobj, 0);
// Owing to pipelining, the PC relative branches below actually skip
// two instructions when the branch offset is 0.
Arm_address destination;
switch (r_type)
{
case elfcpp::R_ARM_CALL:
case elfcpp::R_ARM_JUMP24:
case elfcpp::R_ARM_PLT32:
// ARM branches.
destination = value + addend + 8;
break;
case elfcpp::R_ARM_THM_CALL:
case elfcpp::R_ARM_THM_XPC22:
case elfcpp::R_ARM_THM_JUMP24:
case elfcpp::R_ARM_THM_JUMP19:
// THUMB branches.
destination = value + addend + 4;
break;
default:
gold_unreachable();
}
Stub_type stub_type =
Reloc_stub::stub_type_for_reloc(r_type, address, destination,
target_is_thumb);
// This reloc does not need a stub.
if (stub_type == arm_stub_none)
return;
// Try looking up an existing stub from a stub table.
Stub_table<big_endian>* stub_table =
arm_relobj->stub_table(relinfo->data_shndx);
gold_assert(stub_table != NULL);
// Locate stub by destination.
Reloc_stub::Key stub_key(stub_type, gsym, arm_relobj, r_sym, addend);
// Create a stub if there is not one already
Reloc_stub* stub = stub_table->find_reloc_stub(stub_key);
if (stub == NULL)
{
// create a new stub and add it to stub table.
stub = this->stub_factory().make_reloc_stub(stub_type);
stub_table->add_reloc_stub(stub, stub_key);
}
// Record the destination address.
stub->set_destination_address(destination
| (target_is_thumb ? 1 : 0));
}
// This function scans a relocation sections for stub generation.
// The template parameter Relocate must be a class type which provides
// a single function, relocate(), which implements the machine
// specific part of a relocation.
// BIG_ENDIAN is the endianness of the data. SH_TYPE is the section type:
// SHT_REL or SHT_RELA.
// PRELOCS points to the relocation data. RELOC_COUNT is the number
// of relocs. OUTPUT_SECTION is the output section.
// NEEDS_SPECIAL_OFFSET_HANDLING is true if input offsets need to be
// mapped to output offsets.
// VIEW is the section data, VIEW_ADDRESS is its memory address, and
// VIEW_SIZE is the size. These refer to the input section, unless
// NEEDS_SPECIAL_OFFSET_HANDLING is true, in which case they refer to
// the output section.
template<bool big_endian>
template<int sh_type>
void inline
Target_arm<big_endian>::scan_reloc_section_for_stubs(
const Relocate_info<32, big_endian>* relinfo,
const unsigned char* prelocs,
size_t reloc_count,
Output_section* output_section,
bool needs_special_offset_handling,
const unsigned char* view,
elfcpp::Elf_types<32>::Elf_Addr view_address,
section_size_type)
{
typedef typename Reloc_types<sh_type, 32, big_endian>::Reloc Reltype;
const int reloc_size =
Reloc_types<sh_type, 32, big_endian>::reloc_size;
Arm_relobj<big_endian>* arm_object =
Arm_relobj<big_endian>::as_arm_relobj(relinfo->object);
unsigned int local_count = arm_object->local_symbol_count();
Comdat_behavior comdat_behavior = CB_UNDETERMINED;
for (size_t i = 0; i < reloc_count; ++i, prelocs += reloc_size)
{
Reltype reloc(prelocs);
typename elfcpp::Elf_types<32>::Elf_WXword r_info = reloc.get_r_info();
unsigned int r_sym = elfcpp::elf_r_sym<32>(r_info);
unsigned int r_type = elfcpp::elf_r_type<32>(r_info);
r_type = this->get_real_reloc_type(r_type);
// Only a few relocation types need stubs.
if ((r_type != elfcpp::R_ARM_CALL)
&& (r_type != elfcpp::R_ARM_JUMP24)
&& (r_type != elfcpp::R_ARM_PLT32)
&& (r_type != elfcpp::R_ARM_THM_CALL)
&& (r_type != elfcpp::R_ARM_THM_XPC22)
&& (r_type != elfcpp::R_ARM_THM_JUMP24)
&& (r_type != elfcpp::R_ARM_THM_JUMP19))
continue;
section_offset_type offset =
convert_to_section_size_type(reloc.get_r_offset());
if (needs_special_offset_handling)
{
offset = output_section->output_offset(relinfo->object,
relinfo->data_shndx,
offset);
if (offset == -1)
continue;
}
// Get the addend.
Stub_addend_reader<sh_type, big_endian> stub_addend_reader;
elfcpp::Elf_types<32>::Elf_Swxword addend =
stub_addend_reader(r_type, view + offset, reloc);
const Sized_symbol<32>* sym;
Symbol_value<32> symval;
const Symbol_value<32> *psymval;
if (r_sym < local_count)
{
sym = NULL;
psymval = arm_object->local_symbol(r_sym);
// If the local symbol belongs to a section we are discarding,
// and that section is a debug section, try to find the
// corresponding kept section and map this symbol to its
// counterpart in the kept section. The symbol must not
// correspond to a section we are folding.
bool is_ordinary;
unsigned int shndx = psymval->input_shndx(&is_ordinary);
if (is_ordinary
&& shndx != elfcpp::SHN_UNDEF
&& !arm_object->is_section_included(shndx)
&& !(relinfo->symtab->is_section_folded(arm_object, shndx)))
{
if (comdat_behavior == CB_UNDETERMINED)
{
std::string name =
arm_object->section_name(relinfo->data_shndx);
comdat_behavior = get_comdat_behavior(name.c_str());
}
if (comdat_behavior == CB_PRETEND)
{
bool found;
typename elfcpp::Elf_types<32>::Elf_Addr value =
arm_object->map_to_kept_section(shndx, &found);
if (found)
symval.set_output_value(value + psymval->input_value());
else
symval.set_output_value(0);
}
else
{
symval.set_output_value(0);
}
symval.set_no_output_symtab_entry();
psymval = &symval;
}
}
else
{
const Symbol* gsym = arm_object->global_symbol(r_sym);
gold_assert(gsym != NULL);
if (gsym->is_forwarder())
gsym = relinfo->symtab->resolve_forwards(gsym);
sym = static_cast<const Sized_symbol<32>*>(gsym);
if (sym->has_symtab_index())
symval.set_output_symtab_index(sym->symtab_index());
else
symval.set_no_output_symtab_entry();
// We need to compute the would-be final value of this global
// symbol.
const Symbol_table* symtab = relinfo->symtab;
const Sized_symbol<32>* sized_symbol =
symtab->get_sized_symbol<32>(gsym);
Symbol_table::Compute_final_value_status status;
Arm_address value =
symtab->compute_final_value<32>(sized_symbol, &status);
// Skip this if the symbol has not output section.
if (status == Symbol_table::CFVS_NO_OUTPUT_SECTION)
continue;
symval.set_output_value(value);
psymval = &symval;
}
// If symbol is a section symbol, we don't know the actual type of
// destination. Give up.
if (psymval->is_section_symbol())
continue;
this->scan_reloc_for_stub(relinfo, r_type, sym, r_sym, psymval,
addend, view_address + offset);
}
}
// Scan an input section for stub generation.
template<bool big_endian>
void
Target_arm<big_endian>::scan_section_for_stubs(
const Relocate_info<32, big_endian>* relinfo,
unsigned int sh_type,
const unsigned char* prelocs,
size_t reloc_count,
Output_section* output_section,
bool needs_special_offset_handling,
const unsigned char* view,
Arm_address view_address,
section_size_type view_size)
{
if (sh_type == elfcpp::SHT_REL)
this->scan_reloc_section_for_stubs<elfcpp::SHT_REL>(
relinfo,
prelocs,
reloc_count,
output_section,
needs_special_offset_handling,
view,
view_address,
view_size);
else if (sh_type == elfcpp::SHT_RELA)
// We do not support RELA type relocations yet. This is provided for
// completeness.
this->scan_reloc_section_for_stubs<elfcpp::SHT_RELA>(
relinfo,
prelocs,
reloc_count,
output_section,
needs_special_offset_handling,
view,
view_address,
view_size);
else
gold_unreachable();
}
// Group input sections for stub generation.
//
// We goup input sections in an output sections so that the total size,
// including any padding space due to alignment is smaller than GROUP_SIZE
// unless the only input section in group is bigger than GROUP_SIZE already.
// Then an ARM stub table is created to follow the last input section
// in group. For each group an ARM stub table is created an is placed
// after the last group. If STUB_ALWATS_AFTER_BRANCH is false, we further
// extend the group after the stub table.
template<bool big_endian>
void
Target_arm<big_endian>::group_sections(
Layout* layout,
section_size_type group_size,
bool stubs_always_after_branch)
{
// Group input sections and insert stub table
Layout::Section_list section_list;
layout->get_allocated_sections(&section_list);
for (Layout::Section_list::const_iterator p = section_list.begin();
p != section_list.end();
++p)
{
Arm_output_section<big_endian>* output_section =
Arm_output_section<big_endian>::as_arm_output_section(*p);
output_section->group_sections(group_size, stubs_always_after_branch,
this);
}
}
// Relaxation hook. This is where we do stub generation.
template<bool big_endian>
bool
Target_arm<big_endian>::do_relax(
int pass,
const Input_objects* input_objects,
Symbol_table* symtab,
Layout* layout)
{
// No need to generate stubs if this is a relocatable link.
gold_assert(!parameters->options().relocatable());
// If this is the first pass, we need to group input sections into
// stub groups.
if (pass == 1)
{
// Determine the stub group size. The group size is the absolute
// value of the parameter --stub-group-size. If --stub-group-size
// is passed a negative value, we restict stubs to be always after
// the stubbed branches.
int32_t stub_group_size_param =
parameters->options().stub_group_size();
bool stubs_always_after_branch = stub_group_size_param < 0;
section_size_type stub_group_size = abs(stub_group_size_param);
if (stub_group_size == 1)
{
// Default value.
// Thumb branch range is +-4MB has to be used as the default
// maximum size (a given section can contain both ARM and Thumb
// code, so the worst case has to be taken into account).
//
// This value is 24K less than that, which allows for 2025
// 12-byte stubs. If we exceed that, then we will fail to link.
// The user will have to relink with an explicit group size
// option.
stub_group_size = 4170000;
}
group_sections(layout, stub_group_size, stubs_always_after_branch);
}
// clear changed flags for all stub_tables
typedef typename Stub_table_list::iterator Stub_table_iterator;
for (Stub_table_iterator sp = this->stub_tables_.begin();
sp != this->stub_tables_.end();
++sp)
(*sp)->set_has_been_changed(false);
// scan relocs for stubs
for (Input_objects::Relobj_iterator op = input_objects->relobj_begin();
op != input_objects->relobj_end();
++op)
{
Arm_relobj<big_endian>* arm_relobj =
Arm_relobj<big_endian>::as_arm_relobj(*op);
arm_relobj->scan_sections_for_stubs(this, symtab, layout);
}
bool any_stub_table_changed = false;
for (Stub_table_iterator sp = this->stub_tables_.begin();
(sp != this->stub_tables_.end()) && !any_stub_table_changed;
++sp)
{
if ((*sp)->has_been_changed())
any_stub_table_changed = true;
}
return any_stub_table_changed;
}
// Relocate a stub.
template<bool big_endian>
void
Target_arm<big_endian>::relocate_stub(
Reloc_stub* stub,
const Relocate_info<32, big_endian>* relinfo,
Output_section* output_section,
unsigned char* view,
Arm_address address,
section_size_type view_size)
{
Relocate relocate;
const Stub_template* stub_template = stub->stub_template();
for (size_t i = 0; i < stub_template->reloc_count(); i++)
{
size_t reloc_insn_index = stub_template->reloc_insn_index(i);
const Insn_template* insn = &stub_template->insns()[reloc_insn_index];
unsigned int r_type = insn->r_type();
section_size_type reloc_offset = stub_template->reloc_offset(i);
section_size_type reloc_size = insn->size();
gold_assert(reloc_offset + reloc_size <= view_size);
// This is the address of the stub destination.
Arm_address target = stub->reloc_target(i);
Symbol_value<32> symval;
symval.set_output_value(target);
// Synthesize a fake reloc just in case. We don't have a symbol so
// we use 0.
unsigned char reloc_buffer[elfcpp::Elf_sizes<32>::rel_size];
memset(reloc_buffer, 0, sizeof(reloc_buffer));
elfcpp::Rel_write<32, big_endian> reloc_write(reloc_buffer);
reloc_write.put_r_offset(reloc_offset);
reloc_write.put_r_info(elfcpp::elf_r_info<32>(0, r_type));
elfcpp::Rel<32, big_endian> rel(reloc_buffer);
relocate.relocate(relinfo, this, output_section,
this->fake_relnum_for_stubs, rel, r_type,
NULL, &symval, view + reloc_offset,
address + reloc_offset, reloc_size);
}
}
// The selector for arm object files.
template<bool big_endian>
class Target_selector_arm : public Target_selector
{
public:
Target_selector_arm()
: Target_selector(elfcpp::EM_ARM, 32, big_endian,
(big_endian ? "elf32-bigarm" : "elf32-littlearm"))
{ }
Target*
do_instantiate_target()
{ return new Target_arm<big_endian>(); }
};
Target_selector_arm<false> target_selector_arm;
Target_selector_arm<true> target_selector_armbe;
} // End anonymous namespace.
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