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Update support for .note.gnu.property sections. 

The original patch did not give the target enough hooks to discover that
an input object file does not have a particular property. For the
GNU_PROPERTY_X86_FEATURE_1_AND property, for example, where a missing
property should be assumed to be all zeroes, and ANDed with other
object modules, this is essential. We now store the target-specific
properties locally in the Target structure as native uint32_t fields,
then AND the per-object feature bits with the program's feature bits
when we're finished processing each input object file. The target-specific
properties are then added back to the output note section during
finalization.

gold/
	PR gold/22914
	* layout.cc (read_sized_value): Fix spelling of section name.
	(Layout::layout_gnu_property): Call Sized_target::record_gnu_property
	for target-specific properties;
	don't store them with target-independent properties yet.
	(Layout::merge_gnu_properties): New method.
	(Layout::add_gnu_property): New method.
	(Layout::create_gnu_properties_note): Call target to finalize
	target-specific properties. Fix spelling of output section name.
	* layout.h (Layout::merge_gnu_properties): New method.
	(Layout::add_gnu_property): New method.
	* object.cc (Sized_relobj_file::do_layout): Call
	Layout::merge_gnu_properties.
	* target.h (Target::merge_gnu_property): Remove.
	(Target::finalize_gnu_properties): New method.
	(Target::do_merge_gnu_property): Move to Sized_target and rename.
	(Target::do_finalize_gnu_properties): New virtual method.
	(Sized_target::record_gnu_property): Moved and renamed from
	Target::do_merge_gnu_property.
	(Sized_target::merge_gnu_properties): New virtual method.
	* x86_64.cc (Target_x86_64::isa_1_used_, isa_1_needed_)
	(feature_1_, object_feature_1_, seen_first_object_): New data members.
	(Target_x86_64::do_merge_gnu_property): Rename to ...
	(Target_x86_64::record_gnu_property): ... this.  Save target-specific
	properties in Target class object.
	(Target_x86_64::merge_gnu_properties): New method.
	(add_property): New static inline function.
	(Target_x86_64::do_finalize_gnu_properties): New method.
	* testsuite/Makefile.am (gnu_property_test): Remove C source file;
	link directly without compiler driver.
	* testsuite/Makefile.in: Regenerate.
	* testsuite/gnu_property_a.S: Add _start.
This commit is contained in:
Cary Coutant 2018-06-22 23:36:50 -07:00
parent a1893a821c
commit a2575bec24
9 changed files with 320 additions and 83 deletions
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35
gold/ChangeLog
View File

@ -1,3 +1,38 @@
2018-06-22 Cary Coutant <ccoutant@gmail.com>
PR gold/22914
* layout.cc (read_sized_value): Fix spelling of section name.
(Layout::layout_gnu_property): Call Sized_target::record_gnu_property
for target-specific properties;
don't store them with target-independent properties yet.
(Layout::merge_gnu_properties): New method.
(Layout::add_gnu_property): New method.
(Layout::create_gnu_properties_note): Call target to finalize
target-specific properties. Fix spelling of output section name.
* layout.h (Layout::merge_gnu_properties): New method.
(Layout::add_gnu_property): New method.
* object.cc (Sized_relobj_file::do_layout): Call
Layout::merge_gnu_properties.
* target.h (Target::merge_gnu_property): Remove.
(Target::finalize_gnu_properties): New method.
(Target::do_merge_gnu_property): Move to Sized_target and rename.
(Target::do_finalize_gnu_properties): New virtual method.
(Sized_target::record_gnu_property): Moved and renamed from
Target::do_merge_gnu_property.
(Sized_target::merge_gnu_properties): New virtual method.
* x86_64.cc (Target_x86_64::isa_1_used_, isa_1_needed_)
(feature_1_, object_feature_1_, seen_first_object_): New data members.
(Target_x86_64::do_merge_gnu_property): Rename to ...
(Target_x86_64::record_gnu_property): ... this. Save target-specific
properties in Target class object.
(Target_x86_64::merge_gnu_properties): New method.
(add_property): New static inline function.
(Target_x86_64::do_finalize_gnu_properties): New method.
* testsuite/Makefile.am (gnu_property_test): Remove C source file;
link directly without compiler driver.
* testsuite/Makefile.in: Regenerate.
* testsuite/gnu_property_a.S: Add _start.
2018-06-22 Cary Coutant <ccoutant@gmail.com>
* incremental.cc (Sized_incremental_binary::setup_readers): Use

186
gold/layout.cc
View File

@ -2217,7 +2217,7 @@ read_sized_value(size_t size, const unsigned char* buf, bool is_big_endian,
}
else
{
gold_warning(_("%s: in .note.gnu.properties section, "
gold_warning(_("%s: in .note.gnu.property section, "
"pr_datasz must be 4 or 8"),
object->name().c_str());
}
@ -2262,6 +2262,63 @@ Layout::layout_gnu_property(unsigned int note_type,
// We currently support only the one note type.
gold_assert(note_type == elfcpp::NT_GNU_PROPERTY_TYPE_0);
if (pr_type >= elfcpp::GNU_PROPERTY_LOPROC
&& pr_type < elfcpp::GNU_PROPERTY_HIPROC)
{
// Target-dependent property value; call the target to record.
const int size = parameters->target().get_size();
const bool is_big_endian = parameters->target().is_big_endian();
if (size == 32)
{
if (is_big_endian)
{
#ifdef HAVE_TARGET_32_BIG
parameters->sized_target<32, true>()->
record_gnu_property(note_type, pr_type, pr_datasz, pr_data,
object);
#else
gold_unreachable();
#endif
}
else
{
#ifdef HAVE_TARGET_32_LITTLE
parameters->sized_target<32, false>()->
record_gnu_property(note_type, pr_type, pr_datasz, pr_data,
object);
#else
gold_unreachable();
#endif
}
}
else if (size == 64)
{
if (is_big_endian)
{
#ifdef HAVE_TARGET_64_BIG
parameters->sized_target<64, true>()->
record_gnu_property(note_type, pr_type, pr_datasz, pr_data,
object);
#else
gold_unreachable();
#endif
}
else
{
#ifdef HAVE_TARGET_64_LITTLE
parameters->sized_target<64, false>()->
record_gnu_property(note_type, pr_type, pr_datasz, pr_data,
object);
#else
gold_unreachable();
#endif
}
}
else
gold_unreachable();
return;
}
Gnu_properties::iterator pprop = this->gnu_properties_.find(pr_type);
if (pprop == this->gnu_properties_.end())
{
@ -2273,46 +2330,99 @@ Layout::layout_gnu_property(unsigned int note_type,
}
else
{
if (pr_type >= elfcpp::GNU_PROPERTY_LOPROC
&& pr_type < elfcpp::GNU_PROPERTY_HIPROC)
const bool is_big_endian = parameters->target().is_big_endian();
switch (pr_type)
{
// Target-dependent property value; call the target to merge.
parameters->target().merge_gnu_property(note_type,
pr_type,
pr_datasz,
pr_data,
pprop->second.pr_datasz,
pprop->second.pr_data,
object);
case elfcpp::GNU_PROPERTY_STACK_SIZE:
// Record the maximum value seen.
{
uint64_t val1 = read_sized_value(pprop->second.pr_datasz,
pprop->second.pr_data,
is_big_endian, object);
uint64_t val2 = read_sized_value(pr_datasz, pr_data,
is_big_endian, object);
if (val2 > val1)
write_sized_value(val2, pprop->second.pr_datasz,
pprop->second.pr_data, is_big_endian);
}
break;
case elfcpp::GNU_PROPERTY_NO_COPY_ON_PROTECTED:
// No data to merge.
break;
default:
gold_warning(_("%s: unknown program property type %d "
"in .note.gnu.property section"),
object->name().c_str(), pr_type);
}
}
}
// Merge per-object properties with program properties.
// This lets the target identify objects that are missing certain
// properties, in cases where properties must be ANDed together.
void
Layout::merge_gnu_properties(const Object* object)
{
const int size = parameters->target().get_size();
const bool is_big_endian = parameters->target().is_big_endian();
if (size == 32)
{
if (is_big_endian)
{
#ifdef HAVE_TARGET_32_BIG
parameters->sized_target<32, true>()->merge_gnu_properties(object);
#else
gold_unreachable();
#endif
}
else
{
const bool is_big_endian = parameters->target().is_big_endian();
switch (pr_type)
{
case elfcpp::GNU_PROPERTY_STACK_SIZE:
// Record the maximum value seen.
{
uint64_t val1 = read_sized_value(pprop->second.pr_datasz,
pprop->second.pr_data,
is_big_endian, object);
uint64_t val2 = read_sized_value(pr_datasz, pr_data,
is_big_endian, object);
if (val2 > val1)
write_sized_value(val2, pprop->second.pr_datasz,
pprop->second.pr_data, is_big_endian);
}
break;
case elfcpp::GNU_PROPERTY_NO_COPY_ON_PROTECTED:
// No data to merge.
break;
default:
gold_warning(_("%s: unknown program property type %d "
"in .note.gnu.properties section"),
object->name().c_str(), pr_type);
}
#ifdef HAVE_TARGET_32_LITTLE
parameters->sized_target<32, false>()->merge_gnu_properties(object);
#else
gold_unreachable();
#endif
}
}
else if (size == 64)
{
if (is_big_endian)
{
#ifdef HAVE_TARGET_64_BIG
parameters->sized_target<64, true>()->merge_gnu_properties(object);
#else
gold_unreachable();
#endif
}
else
{
#ifdef HAVE_TARGET_64_LITTLE
parameters->sized_target<64, false>()->merge_gnu_properties(object);
#else
gold_unreachable();
#endif
}
}
else
gold_unreachable();
}
// Add a target-specific property for the output .note.gnu.property section.
void
Layout::add_gnu_property(unsigned int note_type,
unsigned int pr_type,
size_t pr_datasz,
const unsigned char* pr_data)
{
gold_assert(note_type == elfcpp::NT_GNU_PROPERTY_TYPE_0);
Gnu_property prop;
prop.pr_datasz = pr_datasz;
prop.pr_data = new unsigned char[pr_datasz];
memcpy(prop.pr_data, pr_data, pr_datasz);
this->gnu_properties_[pr_type] = prop;
}
// Create automatic note sections.
@ -3144,12 +3254,14 @@ Layout::create_note(const char* name, int note_type,
return os;
}
// Create a .note.gnu.properties section to record program properties
// Create a .note.gnu.property section to record program properties
// accumulated from the input files.
void
Layout::create_gnu_properties_note()
{
parameters->target().finalize_gnu_properties(this);
if (this->gnu_properties_.empty())
return;
@ -3168,7 +3280,7 @@ Layout::create_gnu_properties_note()
// Create the note section.
size_t trailing_padding;
Output_section* os = this->create_note("GNU", elfcpp::NT_GNU_PROPERTY_TYPE_0,
".note.gnu.properties", descsz,
".note.gnu.property", descsz,
true, &trailing_padding);
if (os == NULL)
return;

13
gold/layout.h
View File

@ -701,6 +701,17 @@ class Layout
const unsigned char* pr_data,
const Object* object);
// Merge per-object properties with program properties.
void
merge_gnu_properties(const Object* object);
// Add a target-specific property for the output .note.gnu.property section.
void
add_gnu_property(unsigned int note_type,
unsigned int pr_type,
size_t pr_datasz,
const unsigned char* pr_data);
// Add an Output_section_data to the layout. This is used for
// special sections like the GOT section. ORDER is where the
// section should wind up in the output segment. IS_RELRO is true
@ -1359,7 +1370,7 @@ class Layout
std::vector<Section_info> section_infos_;
};
// Program properties from .note.gnu.properties sections.
// Program properties from .note.gnu.property sections.
struct Gnu_property
{
size_t pr_datasz;

5
gold/object.cc
View File

@ -1862,7 +1862,10 @@ Sized_relobj_file<size, big_endian>::do_layout(Symbol_table* symtab,
}
if (!is_pass_two)
layout->layout_gnu_stack(seen_gnu_stack, gnu_stack_flags, this);
{
layout->merge_gnu_properties(this);
layout->layout_gnu_stack(seen_gnu_stack, gnu_stack_flags, this);
}
// Handle the .eh_frame sections after the other sections.
gold_assert(!is_pass_one || eh_frame_sections.empty());

35
gold/target.h
View File

@ -509,22 +509,10 @@ class Target
should_include_section(elfcpp::Elf_Word sh_type) const
{ return this->do_should_include_section(sh_type); }
// Merge a target-specific program property in the .note.gnu.properties
// section.
// Finalize the target-specific properties in the .note.gnu.property section.
void
merge_gnu_property(int note_type,
int pr_type,
size_t new_pr_datasz,
const unsigned char* new_pr_data,
size_t old_pr_datasz,
unsigned char* old_pr_data,
const Object* object) const
{
return this->do_merge_gnu_property(note_type, pr_type,
new_pr_datasz, new_pr_data,
old_pr_datasz, old_pr_data,
object);
}
finalize_gnu_properties(Layout* layout) const
{ this->do_finalize_gnu_properties(layout); }
protected:
// This struct holds the constant information for a child class. We
@ -832,11 +820,9 @@ class Target
do_should_include_section(elfcpp::Elf_Word) const
{ return true; }
// Merge a target-specific program property in the .note.gnu.properties
// section.
// Finalize the target-specific properties in the .note.gnu.property section.
virtual void
do_merge_gnu_property(int, int, size_t, const unsigned char*,
size_t, unsigned char*, const Object*) const
do_finalize_gnu_properties(Layout*) const
{ }
private:
@ -1158,6 +1144,17 @@ class Sized_target : public Target
return elfcpp::elf_r_sym<size>(rel.get_r_info());
}
// Record a target-specific program property in the .note.gnu.property
// section.
virtual void
record_gnu_property(int, int, size_t, const unsigned char*, const Object*)
{ }
// Merge the target-specific program properties from the current object.
virtual void
merge_gnu_properties(const Object*)
{ }
protected:
Sized_target(const Target::Target_info* pti)
: Target(pti)

4
gold/testsuite/Makefile.am
View File

@ -3260,8 +3260,8 @@ check_SCRIPTS += gnu_property_test.sh
check_DATA += gnu_property_test.stdout
gnu_property_test.stdout: gnu_property_test
$(TEST_READELF) -n $< >$@
gnu_property_test: gcctestdir/ld gnu_property_main.o gnu_property_a.o gnu_property_b.o gnu_property_c.o
$(LINK) -Bgcctestdir/ -o $@ gnu_property_main.o gnu_property_a.o gnu_property_b.o gnu_property_c.o
gnu_property_test: gcctestdir/ld gnu_property_a.o gnu_property_b.o gnu_property_c.o
gcctestdir/ld -o $@ gnu_property_a.o gnu_property_b.o gnu_property_c.o
gnu_property_main.o: gnu_property_main.c
$(COMPILE) -c -o $@ $<
gnu_property_a.o: gnu_property_a.S

4
gold/testsuite/Makefile.in
View File

@ -9465,8 +9465,8 @@ uninstall-am:
@DEFAULT_TARGET_X86_64_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@ $(CXXCOMPILE) -c -Bgcctestdir/ -Wa,-madd-bnd-prefix -o $@ $<
@DEFAULT_TARGET_X86_64_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@gnu_property_test.stdout: gnu_property_test
@DEFAULT_TARGET_X86_64_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@ $(TEST_READELF) -n $< >$@
@DEFAULT_TARGET_X86_64_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@gnu_property_test: gcctestdir/ld gnu_property_main.o gnu_property_a.o gnu_property_b.o gnu_property_c.o
@DEFAULT_TARGET_X86_64_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@ $(LINK) -Bgcctestdir/ -o $@ gnu_property_main.o gnu_property_a.o gnu_property_b.o gnu_property_c.o
@DEFAULT_TARGET_X86_64_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@gnu_property_test: gcctestdir/ld gnu_property_a.o gnu_property_b.o gnu_property_c.o
@DEFAULT_TARGET_X86_64_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@ gcctestdir/ld -o $@ gnu_property_a.o gnu_property_b.o gnu_property_c.o
@DEFAULT_TARGET_X86_64_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@gnu_property_main.o: gnu_property_main.c
@DEFAULT_TARGET_X86_64_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@ $(COMPILE) -c -o $@ $<
@DEFAULT_TARGET_X86_64_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@gnu_property_a.o: gnu_property_a.S

5
gold/testsuite/gnu_property_a.S
View File

@ -11,6 +11,11 @@
# define ALIGN 2
#endif
.text
.globl _start
_start:
ret
.section ".note.gnu.property", "a"
.p2align ALIGN

116
gold/x86_64.cc
View File

@ -590,7 +590,8 @@ class Target_x86_64 : public Sized_target<size, false>
got_tlsdesc_(NULL), global_offset_table_(NULL), rela_dyn_(NULL),
rela_irelative_(NULL), copy_relocs_(elfcpp::R_X86_64_COPY),
got_mod_index_offset_(-1U), tlsdesc_reloc_info_(),
tls_base_symbol_defined_(false)
tls_base_symbol_defined_(false), isa_1_used_(0), isa_1_needed_(0),
feature_1_(0), object_feature_1_(0), seen_first_object_(false)
{ }
// Hook for a new output section.
@ -1188,11 +1189,19 @@ class Target_x86_64 : public Sized_target<size, false>
this->rela_dyn_section(layout));
}
// Merge a target-specific program property in the .note.gnu.properties
// Record a target-specific program property in the .note.gnu.property
// section.
void
do_merge_gnu_property(int, int, size_t, const unsigned char*,
size_t, unsigned char*, const Object*) const;
record_gnu_property(int, int, size_t, const unsigned char*, const Object*);
// Merge the target-specific program properties from the current object.
void
merge_gnu_properties(const Object*);
// Finalize the target-specific program properties and add them back to
// the layout.
void
do_finalize_gnu_properties(Layout*) const;
// Information about this specific target which we pass to the
// general Target structure.
@ -1251,6 +1260,17 @@ class Target_x86_64 : public Sized_target<size, false>
std::vector<Tlsdesc_info> tlsdesc_reloc_info_;
// True if the _TLS_MODULE_BASE_ symbol has been defined.
bool tls_base_symbol_defined_;
// Target-specific program properties, from .note.gnu.property section.
// Each bit represents a specific feature.
uint32_t isa_1_used_;
uint32_t isa_1_needed_;
uint32_t feature_1_;
// Target-specific properties from the current object.
// These bits get ANDed into FEATURE_1_ after all properties for the object
// have been processed.
uint32_t object_feature_1_;
// Whether we have seen our first object, for use in initializing FEATURE_1_.
bool seen_first_object_;
};
template<>
@ -1439,37 +1459,91 @@ Target_x86_64<size>::rela_irelative_section(Layout* layout)
return this->rela_irelative_;
}
// Merge a target-specific program property in the .note.gnu.properties
// Record a target-specific program property from the .note.gnu.property
// section.
template<int size>
void
Target_x86_64<size>::do_merge_gnu_property(
Target_x86_64<size>::record_gnu_property(
int, int pr_type,
size_t new_pr_datasz, const unsigned char* new_pr_data,
size_t old_pr_datasz, unsigned char* old_pr_data,
const Object*) const
size_t pr_datasz, const unsigned char* pr_data,
const Object* object)
{
size_t min_datasz = (new_pr_datasz > old_pr_datasz
? old_pr_datasz
: new_pr_datasz);
uint32_t val;
switch (pr_type)
{
case elfcpp::GNU_PROPERTY_X86_ISA_1_USED:
case elfcpp::GNU_PROPERTY_X86_ISA_1_NEEDED:
{
for (size_t i = 0; i < min_datasz; ++i)
old_pr_data[i] |= new_pr_data[i];
}
break;
case elfcpp::GNU_PROPERTY_X86_FEATURE_1_AND:
{
for (size_t i = 0; i < min_datasz; ++i)
old_pr_data[i] &= new_pr_data[i];
}
if (pr_datasz != 4)
{
gold_warning(_("%s: corrupt .note.gnu.property section "
"(pr_datasz for property %d is not 4)"),
object->name().c_str(), pr_type);
return;
}
val = elfcpp::Swap<32, false>::readval(pr_data);
break;
default:
gold_warning(_("%s: unknown program property type 0x%x "
"in .note.gnu.property section"),
object->name().c_str(), pr_type);
break;
}
switch (pr_type)
{
case elfcpp::GNU_PROPERTY_X86_ISA_1_USED:
this->isa_1_used_ |= val;
break;
case elfcpp::GNU_PROPERTY_X86_ISA_1_NEEDED:
this->isa_1_needed_ |= val;
break;
case elfcpp::GNU_PROPERTY_X86_FEATURE_1_AND:
// If we see multiple feature props in one object, OR them together.
this->object_feature_1_ |= val;
break;
}
}
// Merge the target-specific program properties from the current object.
template<int size>
void
Target_x86_64<size>::merge_gnu_properties(const Object*)
{
if (this->seen_first_object_)
this->feature_1_ &= this->object_feature_1_;
else
{
this->feature_1_ = this->object_feature_1_;
this->seen_first_object_ = true;
}
this->object_feature_1_ = 0;
}
static inline void
add_property(Layout* layout, unsigned int pr_type, uint32_t val)
{
unsigned char buf[4];
elfcpp::Swap<32, false>::writeval(buf, val);
layout->add_gnu_property(elfcpp::NT_GNU_PROPERTY_TYPE_0, pr_type, 4, buf);
}
// Finalize the target-specific program properties and add them back to
// the layout.
template<int size>
void
Target_x86_64<size>::do_finalize_gnu_properties(Layout* layout) const
{
if (this->isa_1_used_ != 0)
add_property(layout, elfcpp::GNU_PROPERTY_X86_ISA_1_USED,
this->isa_1_used_);
if (this->isa_1_needed_ != 0)
add_property(layout, elfcpp::GNU_PROPERTY_X86_ISA_1_NEEDED,
this->isa_1_needed_);
if (this->feature_1_ != 0)
add_property(layout, elfcpp::GNU_PROPERTY_X86_FEATURE_1_AND,
this->feature_1_);
}
// Write the first three reserved words of the .got.plt section.