darkkirb/old-cross-binutils
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity
old-cross-binutils/gold/arm.cc
Doug Kwan a6d1ef576a 2009-11-25 Doug Kwan <dougkwan@google.com> 
Revert:

	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 08:08:45 +00:00

6053 lines
185 KiB
C++
Raw Blame History

This file contains ambiguous Unicode characters

This file contains Unicode characters that might be confused with other characters. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

// 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.
Reference in a new issue View git blame Copy permalink