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Re: [PATCH] gold/arm: define $a/$d markers in .plt
On Wed, Apr 18, 2012 at 2:18 PM, Cary Coutant <ccoutant@google.com> wrote:
> This is purely pedantic/nitpicky, but I think it would be better to
> place the generated locals before the forced locals, so that the
> output symbol table is: (a) locals from relocatables, (b) locals
> generated by the linker, (c) static globals turned into dynamic
> locals, and (d) globals. It just makes a nicer transition.
Ok.
> Again, nitpicky, but maybe we want to change the name of the typedef
> Forced_locals?
Sure.
Here's a new patch (same effect, same testing) incorporating these
and your earlier suggestion.
Ok for trunk?
Thanks,
Roland
gold/
2012-04-18 Roland McGrath <mcgrathr@google.com>
* arm.cc (Output_data_plt_arm::add_marker_symbols): New method.
(Output_data_plt_arm::add_marker_symbol): New method.
(Target_arm::make_plt_entry): Call it.
* symtab.h (Symbol_table::Forced_locals): Rename to ...
(Symbol_table::Symbol_vector): ... this.
(Symbol_table::forced_locals_): Update type.
(Symbol_table::generated_locals_): New member.
* symtab.cc (Symbol_table::Symbol_table): Initialize it.
(Symbol_table::do_define_in_output_data): Don't use
define_special_symbol for STB_LOCAL. Instead, just create a symbol
and add it to generated_locals_.
(Symbol_table::sized_finalize): Update use of type name.
Add generated_locals_ to symtab similar to forced_locals_.
(Symbol_table::sized_write_globals): Write generated_locals_ out.
diff --git a/gold/arm.cc b/gold/arm.cc
index dc6e64a..0bed822 100644
--- a/gold/arm.cc
+++ b/gold/arm.cc
@@ -7223,8 +7223,31 @@ class Output_data_plt_arm : public Output_section_data
get_plt_entry_size()
{ return sizeof(plt_entry); }
+ // Define marker symbols at the start of the PLT so that
+ // objdump will know to disassemble it as ARM instructions.
+ void
+ add_marker_symbols(Output_section* os, Symbol_table* symtab)
+ {
+ // The last word of first_plt_entry is data.
+ // The leading words, and all of subsequent entries, are ARM instructions.
+ this->add_marker_symbol(os, symtab, 0, false);
+ this->add_marker_symbol(os, symtab, 16, true);
+ this->add_marker_symbol(os, symtab, 20, false);
+ }
+
protected:
void
+ add_marker_symbol(Output_section* os, Symbol_table* symtab,
+ Arm_address offset, bool is_data)
+ {
+ symtab->define_in_output_data(is_data ? "$d" : "$a", NULL,
+ Symbol_table::PREDEFINED, os,
+ offset, 0, elfcpp::STT_NOTYPE,
+ elfcpp::STB_LOCAL, elfcpp::STV_DEFAULT, 0,
+ false, false);
+ }
+
+ void
do_adjust_output_section(Output_section* os);
// Write to a map file.
@@ -7430,10 +7453,13 @@
Target_arm<big_endian>::make_plt_entry(Symbol_table* symtab, Layout*
layout,
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),
+
+ Output_section* os = layout->add_output_section_data
+ (".plt", elfcpp::SHT_PROGBITS,
+ (elfcpp::SHF_ALLOC | elfcpp::SHF_EXECINSTR),
this->plt_, ORDER_PLT, false);
+
+ this->plt_->add_marker_symbols(os, symtab);
}
this->plt_->add_entry(gsym);
}
diff --git a/gold/symtab.cc b/gold/symtab.cc
index 1edb88d..5e2d6fc 100644
--- a/gold/symtab.cc
+++ b/gold/symtab.cc
@@ -1,6 +1,6 @@
// symtab.cc -- the gold symbol table
-// Copyright 2006, 2007, 2008, 2009, 2010, 2011 Free Software Foundation, Inc.
+// Copyright 2006,2007,2008,2009,2010,2011,2012 Free Software Foundation, Inc.
// Written by Ian Lance Taylor <iant@google.com>.
// This file is part of gold.
@@ -532,7 +532,7 @@ Symbol_table::Symbol_table(unsigned int count,
const Version_script_info& version_script)
: saw_undefined_(0), offset_(0), table_(count), namepool_(),
forwarders_(), commons_(), tls_commons_(), small_commons_(),
- large_commons_(), forced_locals_(), warnings_(),
+ large_commons_(), forced_locals_(), generated_locals_(), warnings_(),
version_script_(version_script), gc_(NULL), icf_(NULL)
{
namepool_.reserve(count);
@@ -1884,7 +1884,33 @@ Symbol_table::do_define_in_output_data(
Sized_symbol<size>* oldsym;
bool resolve_oldsym;
- if (parameters->target().is_big_endian())
+ if (binding == elfcpp::STB_LOCAL)
+ {
+ // This is a special local symbol, so it doesn't need to be
+ // in the symbol table by name. Just make a naked symbol.
+ // We'll add it to the generated_locals_ list below.
+ const Target& target = parameters->target();
+ if (!target.has_make_symbol())
+ sym = new Sized_symbol<size>();
+ else
+ {
+ if (parameters->target().is_big_endian())
+ {
+ Sized_target<size, true>* sized_target =
+ parameters->sized_target<size, true>();
+ sym = sized_target->make_symbol();
+ }
+ else
+ {
+ Sized_target<size, false>* sized_target =
+ parameters->sized_target<size, false>();
+ sym = sized_target->make_symbol();
+ }
+ }
+
+ oldsym = NULL;
+ }
+ else if (parameters->target().is_big_endian())
{
#if defined(HAVE_TARGET_32_BIG) || defined(HAVE_TARGET_64_BIG)
sym = this->define_special_symbol<size, true>(&name, &version,
@@ -1919,6 +1945,8 @@ Symbol_table::do_define_in_output_data(
this->force_local(sym);
else if (version != NULL)
sym->set_is_default();
+ if (binding == elfcpp::STB_LOCAL)
+ this->generated_locals_.push_back(sym);
return sym;
}
@@ -2500,9 +2528,24 @@ Symbol_table::sized_finalize(off_t off, Stringpool* pool,
unsigned int index = *plocal_symcount;
const unsigned int orig_index = index;
- // First do all the symbols which have been forced to be local, as
+ // First do all the symbols which have been generated as local, as
// they must appear before all global symbols.
- for (Forced_locals::iterator p = this->forced_locals_.begin();
+ for (Symbol_vector::iterator p = this->generated_locals_.begin();
+ p != this->generated_locals_.end();
+ ++p)
+ {
+ Symbol* sym = *p;
+ gold_assert(sym->is_forced_local());
+ if (this->sized_finalize_symbol<size>(sym))
+ {
+ this->add_to_final_symtab<size>(sym, pool, &index, &off);
+ ++*plocal_symcount;
+ }
+ }
+
+ // Next do all the symbols which have been forced to be local.
+ // They too must appear before all global symbols.
+ for (Symbol_vector::iterator p = this->forced_locals_.begin();
p != this->forced_locals_.end();
++p)
{
@@ -2976,6 +3019,36 @@ Symbol_table::sized_write_globals(const
Stringpool* sympool,
}
}
+ // Next do all the symbols which have been generated as local.
+ for (Symbol_vector::const_iterator p = this->generated_locals_.begin();
+ p != this->generated_locals_.end();
+ ++p)
+ {
+ Sized_symbol<size>* sym = static_cast<Sized_symbol<size>*>(*p);
+ unsigned int sym_index = sym->symtab_index();
+ unsigned int shndx = sym->output_data()->out_shndx();
+ typename elfcpp::Elf_types<size>::Elf_Addr sym_value = sym->value();
+
+ gold_assert(sym->binding() == elfcpp::STB_LOCAL);
+
+ if (shndx >= elfcpp::SHN_LORESERVE)
+ {
+ if (sym_index != -1U)
+ symtab_xindex->add(sym_index, shndx);
+ shndx = elfcpp::SHN_XINDEX;
+ }
+
+ if (sym_index != -1U)
+ {
+ sym_index -= first_global_index;
+ gold_assert(sym_index < output_count);
+ unsigned char* ps = psyms + (sym_index * sym_size);
+ this->sized_write_symbol<size, big_endian>(sym, sym_value, shndx,
+ elfcpp::STB_LOCAL,
+ sympool, ps);
+ }
+ }
+
of->write_output_view(this->offset_, oview_size, psyms);
if (dynamic_view != NULL)
of->write_output_view(this->dynamic_offset_, dynamic_size, dynamic_view);
diff --git a/gold/symtab.h b/gold/symtab.h
index feed245..94942b2 100644
--- a/gold/symtab.h
+++ b/gold/symtab.h
@@ -1,6 +1,6 @@
// symtab.h -- the gold symbol table -*- C++ -*-
-// Copyright 2006, 2007, 2008, 2009, 2010, 2011 Free Software Foundation, Inc.
+// Copyright 2006,2007,2008,2009,2010,2011,2012 Free Software Foundation, Inc.
// Written by Ian Lance Taylor <iant@google.com>.
// This file is part of gold.
@@ -1822,8 +1822,8 @@ class Symbol_table
sized_write_section_symbol(const Output_section*, Output_symtab_xindex*,
Output_file*, off_t) const;
- // The type of the list of symbols which have been forced local.
- typedef std::vector<Symbol*> Forced_locals;
+ // The type of a simple vector of symbols.
+ typedef std::vector<Symbol*> Symbol_vector;
// A map from symbols with COPY relocs to the dynamic objects where
// they are defined.
@@ -1871,7 +1871,9 @@ class Symbol_table
// A list of symbols which have been forced to be local. We don't
// expect there to be very many of them, so we keep a list of them
// rather than walking the whole table to find them.
- Forced_locals forced_locals_;
+ Symbol_vector forced_locals_;
+ // A list of symbols that were generated as local.
+ Symbol_vector generated_locals_;
// Manage symbol warnings.
Warnings warnings_;
// Manage potential One Definition Rule (ODR) violations.