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2009-10-28 Doug Kwan <dougkwan@google.com> 

* arm.cc (Arm_relobj): New class definition.
	(Arm_relobj::scan_sections_for_stubs,
	Arm_relobj::do_count_local_symbols, Arm_relobj::do_relocate_sections):
	New method definitions.
This commit is contained in:
Doug Kwan 2009-10-29 01:53:35 +00:00
parent 72737fba23
commit 8ffa366761
2 changed files with 355 additions and 0 deletions
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7
gold/ChangeLog
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@ -1,3 +1,10 @@
2009-10-28 Doug Kwan <dougkwan@google.com>
* arm.cc (Arm_relobj): New class definition.
(Arm_relobj::scan_sections_for_stubs,
Arm_relobj::do_count_local_symbols, Arm_relobj::do_relocate_sections):
New method definitions.
2009-10-28 Cary Coutant <ccoutant@google.com>
* plugin.h (Plugin::Plugin): Initialize cleanup_done_.

348
gold/arm.cc
View File

@ -884,6 +884,102 @@ class Arm_output_section : public Output_section
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); }
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 General_options& options,
const Symbol_table* symtab, const Layout* layout,
const unsigned char* pshdrs,
typename Sized_relobj<32, big_endian>::Views* pivews);
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_;
};
// Utilities for manipulating integers of up to 32-bits
namespace utils
@ -2908,6 +3004,258 @@ Arm_output_section<big_endian>::group_sections(
}
}
// 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.options = &parameters->options();
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 General_options& options,
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(options, 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.options = &options;
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);
}
}
// A class to handle the PLT data.
template<bool big_endian>