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darling-gdb/gold/arm.cc
Ian Lance Taylor 8a5e3e08a6 * layout.cc (Layout::make_output_section): Call 
Target::new_output_section.
	(Layout::attach_allocated_section_to_segment): Put large section
	sections in a separate load segment with the large segment flag
	set.
	(Layout::segment_precedes): Sort large data segments after other
	load segments.
	(align_file_offset): New static function.
	(Layout::set_segment_offsets): Use align_file_offset.
	* output.h (class Output_section): Add is_small_section_ and
	is_large_section_ fields.
	(Output_section::is_small_section): New function.
	(Output_section::set_is_small_section):  New function.
	(Output_section::is_large_section): New function.
	(Output_section::set_is_large_section): New function.
	(Output_section::is_large_data_section): New function.
	(class Output_segment): Add is_large_data_segment_ field.
	(Output_segment::is_large_data_segment): New function.
	(Output_segment::set_is_large_data_segment): New function.
	* output.cc (Output_section::Output_section): Initialize new
	fields.
	(Output_segment::Output_segment): Likewise.
	(Output_segment::add_output_section): Add assertion that large
	data sections always go in large data segments.  Force small data
	sections to the end of the list of data sections.  Force small BSS
	sections to the start of the list of BSS sections.  For large BSS
	sections to the end of the list of BSS sections.
	* symtab.h (class Symbol): Declare is_common_shndx.
	(Symbol::is_defined): Check Symbol::is_common_shndx.
	(Symbol::is_common): Likewise.
	(class Symbol_table): Define enum Commons_section_type.  Update
	declarations.  Add small_commons_ and large_commons_ fields.
	* symtab.cc (Symbol::is_common_shndx): New function.
	(Symbol_table::Symbol_table): Initialize new fields.
	(Symbol_table::add_from_object): Put small and large common
	symbols in the right list.
	(Symbol_table::sized_finalized_symbol): Check
	Symbol::is_common_shndx.
	(Symbol_table::sized_write_globals): Likewise.
	* common.cc (Symbol_table::do_allocate_commons): Allocate new
	common symbol lists.  Don't call do_allocate_commons_list if the
	list is empty.
	(Symbol_table::do_allocate_commons_list): Remove is_tls
	parameter.  Add comons_section_type parameter.  Change all
	callers.  Handle small and large common symbols.
	* object.cc (Sized_relobj::do_finalize_local_symbols): Check
	Symbol::is_common_shndx.
	* resolve.cc (symbol_to_bits): Likewise.
	* target.h (Target::small_common_shndx): New function.
	(Target::small_common_section_flags): New function.
	(Target::large_common_shndx): New function.
	(Target::large_common_section_flags): New function.
	(Target::new_output_section): New function.
	(Target::Target_info): Add small_common_shndx, large_common_shndx,
	small_common_section_flags, and large_common_section_flags
	fields.
	(Target::do_new_output_section): New virtual function.
	* arm.cc (Target_arm::arm_info): Initialize new fields.
	* i386.cc (Target_i386::i386_info): Likewise.
	* powerpc.cc (Target_powerpc::powerpc_info) [all versions]:
	Likewise.
	* sparc.c (Target_sparc::sparc_info) [all versions]: Likewise.
	* x86_64.cc (Target_x86_64::x86_64_info): Likewise.
	(Target_x86_64::do_new_output_section): New function.
	* configure.ac: Define conditional MCMODEL_MEDIUM.
	* testsuite/Makefile.am (check_PROGRAMS): Add large.
	(large_SOURCES, large_CFLAGS, large_DEPENDENCIES): Define.
	(large_LDFLAGS): Define.
	* testsuite/large.c: New file.
	* testsuite/testfile.cc (Target_test::test_target_info):
	Initialize new fields.
	* configure, testsuite/Makefile.in: Rebuild.
2009-06-22 06:51:53 +00:00

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// arm.cc -- arm target support for gold.
// Copyright 2009 Free Software Foundation, Inc.
// Written by Doug Kwan <dougkwan@google.com> based on the i386 code
// by Ian Lance Taylor <iant@google.com>.
// This file 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 "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"
namespace
{
using namespace gold;
template<bool big_endian>
class Output_data_plt_arm;
// 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_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_PLT32
// R_ARM_CALL
// R_ARM_JUMP24
// R_ARM_TARGET1
// R_ARM_PREL31
//
// Coming soon (pending patches):
// - Defining section symbols __exidx_start and __exidx_stop.
// - Support interworking.
// - Mergeing all .ARM.xxx.yyy sections into .ARM.xxx. Currently, they
// are incorrectly merged into an .ARM section.
//
// TODOs:
// - Create a PT_ARM_EXIDX program header for a shared object that
// might throw an exception.
// - Support more relocation types as needed.
// - Make PLTs more flexible for different architecture features like
// Thumb-2 and BE8.
// 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;
}
// 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;
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)
{ }
// Process the relocations to determine unreferenced sections for
// garbage collection.
void
gc_process_relocs(const General_options& options,
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(const General_options& options,
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*);
// 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,
elfcpp::Elf_types<32>::Elf_Addr view_address,
section_size_type view_size);
// Scan the relocs during a relocatable link.
void
scan_relocatable_relocs(const General_options& options,
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,
elfcpp::Elf_types<32>::Elf_Addr 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);
private:
// The class which scans relocations.
class Scan
{
public:
Scan()
: issued_non_pic_error_(false)
{ }
inline void
local(const General_options& options, 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(const General_options& options, 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*, elfcpp::Elf_types<32>::Elf_Addr,
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:
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 (!parameters->options().shared()
&& gsym->is_from_dynobj()
&& gsym->type() != elfcpp::STT_FUNC
&& gsym->type() != elfcpp::STT_ARM_TFUNC);
}
// 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));
}
// 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
};
// 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_;
};
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;
// Get an symbol value of *PSYMVAL with an ADDEND. This is a wrapper
// to Symbol_value::value(). If HAS_THUMB_BIT is true, that LSB is used
// to distinguish ARM and THUMB functions and it is treated specially.
static inline Symbol_value<32>::Value
arm_symbol_value (const Sized_relobj<32, big_endian> *object,
const Symbol_value<32>* psymval,
Symbol_value<32>::Value addend,
bool has_thumb_bit)
{
typedef Symbol_value<32>::Value Valtype;
if (has_thumb_bit)
{
Valtype raw = psymval->value(object, 0);
Valtype thumb_bit = raw & 1;
return ((raw & ~((Valtype) 1)) + addend) | thumb_bit;
}
else
return psymval->value(object, addend);
}
// FIXME: This probably only works for Android on ARM v5te. We should
// following GNU ld for the general case.
template<unsigned r_type>
static inline typename This::Status
arm_branch_common(unsigned char *view,
const Sized_relobj<32, big_endian>* object,
const Symbol_value<32>* psymval,
elfcpp::Elf_types<32>::Elf_Addr address,
bool has_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);
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;
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
gold_unreachable();
Valtype addend = utils::sign_extend<26>(val << 2);
Valtype x = (This::arm_symbol_value(object, psymval, addend, has_thumb_bit)
- address);
// If target has thumb bit set, we need to either turn the BL
// into a BLX (for ARMv5 or above) or generate a stub.
if (x & 1)
{
// Turn BL to BLX.
if (insn_is_uncond_bl)
val = (val & 0xffffff) | 0xfa000000 | ((x & 2) << 23);
else
return This::STATUS_BAD_RELOC;
}
else
gold_assert(!insn_is_blx);
val = utils::bit_select(val, (x >> 2), 0xffffffUL);
elfcpp::Swap<32, big_endian>::writeval(wv, val);
return (utils::has_overflow<26>(x)
? This::STATUS_OVERFLOW : This::STATUS_OKAY);
}
public:
// 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,
bool has_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 = This::arm_symbol_value(object, psymval, addend, has_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,
elfcpp::Elf_types<32>::Elf_Addr address,
bool has_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 = (This::arm_symbol_value(object, psymval, addend, has_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(unsigned char *view,
const Sized_relobj<32, big_endian>* object,
const Symbol_value<32>* psymval,
elfcpp::Elf_types<32>::Elf_Addr address,
bool has_thumb_bit)
{
// A thumb call consists of two instructions.
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 hi = elfcpp::Swap<16, big_endian>::readval(wv);
Valtype lo = elfcpp::Swap<16, big_endian>::readval(wv + 1);
// Must be a BL instruction. lo == 11111xxxxxxxxxxx.
gold_assert((lo & 0xf800) == 0xf800);
Reltype addend = utils::sign_extend<23>(((hi & 0x7ff) << 12)
| ((lo & 0x7ff) << 1));
Reltype x = (This::arm_symbol_value(object, psymval, addend, has_thumb_bit)
- address);
// If target has no thumb bit set, we need to either turn the BL
// into a BLX (for ARMv5 or above) or generate a stub.
if ((x & 1) == 0)
{
// This only works for ARMv5 and above with interworking enabled.
lo &= 0xefff;
}
hi = utils::bit_select(hi, (x >> 12), 0x7ffU);
lo = utils::bit_select(lo, (x >> 1), 0x7ffU);
elfcpp::Swap<16, big_endian>::writeval(wv, hi);
elfcpp::Swap<16, big_endian>::writeval(wv + 1, lo);
return (utils::has_overflow<23>(x)
? This::STATUS_OVERFLOW
: This::STATUS_OKAY);
}
// R_ARM_BASE_PREL: B(S) + A - P
static inline typename This::Status
base_prel(unsigned char* view,
elfcpp::Elf_types<32>::Elf_Addr origin,
elfcpp::Elf_types<32>::Elf_Addr address)
{
Base::rel32(view, origin - address);
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_PLT32: (S + A) | T - P
static inline typename This::Status
plt32(unsigned char *view,
const Sized_relobj<32, big_endian>* object,
const Symbol_value<32>* psymval,
elfcpp::Elf_types<32>::Elf_Addr address,
bool has_thumb_bit)
{
return arm_branch_common<elfcpp::R_ARM_PLT32>(view, object, psymval,
address, has_thumb_bit);
}
// R_ARM_CALL: (S + A) | T - P
static inline typename This::Status
call(unsigned char *view,
const Sized_relobj<32, big_endian>* object,
const Symbol_value<32>* psymval,
elfcpp::Elf_types<32>::Elf_Addr address,
bool has_thumb_bit)
{
return arm_branch_common<elfcpp::R_ARM_CALL>(view, object, psymval,
address, has_thumb_bit);
}
// R_ARM_JUMP24: (S + A) | T - P
static inline typename This::Status
jump24(unsigned char *view,
const Sized_relobj<32, big_endian>* object,
const Symbol_value<32>* psymval,
elfcpp::Elf_types<32>::Elf_Addr address,
bool has_thumb_bit)
{
return arm_branch_common<elfcpp::R_ARM_JUMP24>(view, object, psymval,
address, has_thumb_bit);
}
// 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,
elfcpp::Elf_types<32>::Elf_Addr address,
bool has_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 = (This::arm_symbol_value(object, psymval, addend, has_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);
}
};
// 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_);
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_);
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_);
}
return this->rel_dyn_;
}
// 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_);
}
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;
elfcpp::Elf_types<32>::Elf_Addr plt_address = this->address();
elfcpp::Elf_types<32>::Elf_Addr 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_);
}
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_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(const General_options&,
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:
// 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:
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:
{
// 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(const General_options&,
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:
{
// 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_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:
{
// 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(const General_options& options,
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>(
options,
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(const General_options& options,
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>(
options,
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)
{
// Fill in some more dynamic tags.
Output_data_dynamic* const odyn = layout->dynamic_data();
if (odyn != NULL)
{
if (this->got_plt_ != NULL)
odyn->add_section_address(elfcpp::DT_PLTGOT, this->got_plt_);
if (this->plt_ != 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)
{
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));
}
// 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,
elfcpp::Elf_types<32>::Elf_Addr address,
section_size_type /* view_size */ )
{
typedef Arm_relocate_functions<big_endian> Arm_relocate_functions;
r_type = get_real_reloc_type(r_type);
// If this the symbol may be a Thumb function, set thumb bit to 1.
bool has_thumb_bit = ((gsym != NULL)
&& (gsym->type() == elfcpp::STT_FUNC
|| gsym->type() == elfcpp::STT_ARM_TFUNC));
// Pick the value to use for symbols defined in shared objects.
Symbol_value<32> symval;
if (gsym != NULL
&& gsym->use_plt_offset(reloc_is_non_pic(r_type)))
{
symval.set_output_value(target->plt_section()->address()
+ gsym->plt_offset());
psymval = &symval;
has_thumb_bit = 0;
}
const Sized_relobj<32, big_endian>* object = relinfo->object;
// Get the GOT offset if needed.
// The GOT pointer points to the end of the GOT section.
// We need to subtract the size of the GOT section to get
// the actual offset to use in the relocation.
bool have_got_offset = false;
unsigned int got_offset = 0;
switch (r_type)
{
case elfcpp::R_ARM_GOT_BREL:
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;
}
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_ABS32:
if (should_apply_static_reloc(gsym, Symbol::ABSOLUTE_REF, true,
output_section))
reloc_status = Arm_relocate_functions::abs32(view, object, psymval,
has_thumb_bit);
break;
case elfcpp::R_ARM_REL32:
reloc_status = Arm_relocate_functions::rel32(view, object, psymval,
address, has_thumb_bit);
break;
case elfcpp::R_ARM_THM_CALL:
reloc_status = Arm_relocate_functions::thm_call(view, object, psymval,
address, has_thumb_bit);
break;
case elfcpp::R_ARM_GOTOFF32:
{
elfcpp::Elf_types<32>::Elf_Addr got_origin;
got_origin = target->got_plt_section()->address();
reloc_status = Arm_relocate_functions::rel32(view, object, psymval,
got_origin, has_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_GOT_BREL:
gold_assert(have_got_offset);
reloc_status = Arm_relocate_functions::got_brel(view, got_offset);
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(view, object, psymval,
address, has_thumb_bit);
break;
case elfcpp::R_ARM_CALL:
reloc_status = Arm_relocate_functions::call(view, object, psymval,
address, has_thumb_bit);
break;
case elfcpp::R_ARM_JUMP24:
reloc_status = Arm_relocate_functions::jump24(view, object, psymval,
address, has_thumb_bit);
break;
case elfcpp::R_ARM_PREL31:
reloc_status = Arm_relocate_functions::prel31(view, object, psymval,
address, has_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,
elfcpp::Elf_types<32>::Elf_Addr address,
section_size_type view_size)
{
typedef typename Target_arm<big_endian>::Relocate Arm_relocate;
gold_assert(sh_type == elfcpp::SHT_REL);
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);
}
// 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_ABS32:
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_PLT32:
case elfcpp::R_ARM_CALL:
case elfcpp::R_ARM_JUMP24:
case elfcpp::R_ARM_PREL31:
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(
const General_options& options,
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>(
options,
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,
elfcpp::Elf_types<32>::Elf_Addr view_address,
section_size_type view_size,
unsigned char* reloc_view,
section_size_type reloc_view_size)
{
gold_assert(sh_type == elfcpp::SHT_REL);
gold::relocate_for_relocatable<32, 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;
}
}
// The selector for arm object files.
template<bool big_endian>
class Target_selector_arm : public Target_selector
{
public:
Target_selector_arm()
: Target_selector(elfcpp::EM_ARM, 32, big_endian,
(big_endian ? "elf32-bigarm" : "elf32-littlearm"))
{ }
Target*
do_instantiate_target()
{ return new Target_arm<big_endian>(); }
};
Target_selector_arm<false> target_selector_arm;
Target_selector_arm<true> target_selector_armbe;
} // End anonymous namespace.
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