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With -pie and x86, the linker complains if it sees a PC-relative relocation

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to access a global as it expects a GOTPCREL relocation.  This is really not
necessary as the linker could use a copy relocation to get around it.  This
patch enables copy relocations with pie.

Context:
This is useful because currently the GCC compiler with option -fpie makes
every extern global access go through the GOT. That is because the compiler
cannot tell if a global will end up being defined in the executable or not
and is conservative. This ends up hurting performance when the binary is linked
as mostly static where most of the globals do end up being defined in the
executable.  By allowing copy relocs with fPIE, the compiler need not generate
a GOTPCREL(GOT access) for any global access.  It can safely assume that all
globals will be defined in the executable and generate a PC-relative access
instead.  Gold can then create a copy reloc for only the undefined globals.

	gold/
	* symtab.h (may_need_copy_reloc): Remove check for position independent
	code.
	* x86_64.cc (Target_x86_64<size>::Scan::global): Add check for no
	position independence before pc absolute may_need_copy_reloc call.
	Add check for executable output befor pc relative may_need_copy_reloc
	call.
	* i386.cc: Ditto.
	* arm.cc: Ditto.
	* sparc.cc: Ditto.
	* tilegx.cc: Ditto.
	* powerpc.cc: Add check for no position independence before
	may_need_copy_reloc calls.
	* testsuite/pie_copyrelocs_test.cc: New file.
	* testsuite/pie_copyrelocs_shared_test.cc: New file.
	* Makefile.am (pie_copyrelocs_test): New test.
	* Makefile.in: Regenerate.
This commit is contained in:
Sriraman Tallam 2014-05-13 10:51:48 -07:00
parent 033c337911
commit a82bef932e
10 changed files with 86 additions and 24 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

19
gold/ChangeLog
View File

@ -1,3 +1,22 @@
2014-05-13 Sriraman Tallam <tmsriram@google.com>
* symtab.h (may_need_copy_reloc): Remove check for position independent
code.
* x86_64.cc (Target_x86_64<size>::Scan::global): Add check for no
position independence before pc absolute may_need_copy_reloc call.
Add check for executable output befor pc relative may_need_copy_reloc
call.
* i386.cc: Ditto.
* arm.cc: Ditto.
* sparc.cc: Ditto.
* tilegx.cc: Ditto.
* powerpc.cc: Add check for no position independence before
may_need_copy_reloc calls.
* testsuite/pie_copyrelocs_test.cc: New file.
* testsuite/pie_copyrelocs_shared_test.cc: New file.
* Makefile.am (pie_copyrelocs_test): New test.
* Makefile.in: Regenerate.
2014-05-08 Martin Liška <mliska@suse.cz>
* output.cc (Sized_relobj_file::do_layout): Fix typo in info message.

6
gold/arm.cc
View File

@ -8301,7 +8301,8 @@ Target_arm<big_endian>::Scan::global(Symbol_table* symtab,
// Make a dynamic relocation if necessary.
if (gsym->needs_dynamic_reloc(Scan::get_reference_flags(r_type)))
{
if (gsym->may_need_copy_reloc())
if (!parameters->options().output_is_position_independent()
&& gsym->may_need_copy_reloc())
{
target->copy_reloc(symtab, layout, object,
data_shndx, output_section, gsym, reloc);
@ -8382,7 +8383,8 @@ Target_arm<big_endian>::Scan::global(Symbol_table* symtab,
// Make a dynamic relocation if necessary.
if (gsym->needs_dynamic_reloc(Scan::get_reference_flags(r_type)))
{
if (target->may_need_copy_reloc(gsym))
if (parameters->options().output_is_executable()
&& target->may_need_copy_reloc(gsym))
{
target->copy_reloc(symtab, layout, object,
data_shndx, output_section, gsym, reloc);

6
gold/i386.cc
View File

@ -2149,7 +2149,8 @@ Target_i386::Scan::global(Symbol_table* symtab,
// Make a dynamic relocation if necessary.
if (gsym->needs_dynamic_reloc(Scan::get_reference_flags(r_type)))
{
if (gsym->may_need_copy_reloc())
if (!parameters->options().output_is_position_independent()
&& gsym->may_need_copy_reloc())
{
target->copy_reloc(symtab, layout, object,
data_shndx, output_section, gsym, reloc);
@ -2210,7 +2211,8 @@ Target_i386::Scan::global(Symbol_table* symtab,
// Make a dynamic relocation if necessary.
if (gsym->needs_dynamic_reloc(Scan::get_reference_flags(r_type)))
{
if (gsym->may_need_copy_reloc())
if (parameters->options().output_is_executable()
&& gsym->may_need_copy_reloc())
{
target->copy_reloc(symtab, layout, object,
data_shndx, output_section, gsym, reloc);

6
gold/powerpc.cc
View File

@ -5819,7 +5819,8 @@ Target_powerpc<size, big_endian>::Scan::global(
if (gsym->needs_dynamic_reloc(Scan::get_reference_flags(r_type, target))
|| (size == 64 && is_ifunc && target->abiversion() < 2))
{
if (gsym->may_need_copy_reloc())
if (!parameters->options().output_is_position_independent()
&& gsym->may_need_copy_reloc())
{
target->copy_reloc(symtab, layout, object,
data_shndx, output_section, gsym, reloc);
@ -5882,7 +5883,8 @@ Target_powerpc<size, big_endian>::Scan::global(
// Make a dynamic relocation if necessary.
if (gsym->needs_dynamic_reloc(Scan::get_reference_flags(r_type, target)))
{
if (gsym->may_need_copy_reloc())
if (!parameters->options().output_is_position_independent()
&& gsym->may_need_copy_reloc())
{
target->copy_reloc(symtab, layout, object,
data_shndx, output_section, gsym,

6
gold/sparc.cc
View File

@ -2634,7 +2634,8 @@ Target_sparc<size, big_endian>::Scan::global(
// Make a dynamic relocation if necessary.
if (gsym->needs_dynamic_reloc(Scan::get_reference_flags(r_type)))
{
if (gsym->may_need_copy_reloc())
if (parameters->options().output_is_executable()
&& gsym->may_need_copy_reloc())
{
target->copy_reloc(symtab, layout, object,
data_shndx, output_section, gsym,
@ -2723,7 +2724,8 @@ Target_sparc<size, big_endian>::Scan::global(
break;
}
if (gsym->may_need_copy_reloc())
if (!parameters->options().output_is_position_independent()
&& gsym->may_need_copy_reloc())
{
target->copy_reloc(symtab, layout, object,
data_shndx, output_section, gsym, reloc);

3
gold/symtab.h
View File

@ -847,8 +847,7 @@ class Symbol
bool
may_need_copy_reloc() const
{
return (!parameters->options().output_is_position_independent()
&& parameters->options().copyreloc()
return (parameters->options().copyreloc()
&& this->is_from_dynobj()
&& !this->is_func());
}

10
gold/testsuite/Makefile.am
View File

@ -517,6 +517,16 @@ two_file_pie_test: two_file_test_1_pie.o two_file_test_1b_pie.o \
two_file_test_2_pie.o two_file_test_main_pie.o gcctestdir/ld
$(CXXLINK) -Bgcctestdir/ -pie two_file_test_1_pie.o two_file_test_1b_pie.o two_file_test_2_pie.o two_file_test_main_pie.o
check_PROGRAMS += pie_copyrelocs_test
pie_copyrelocs_test_SOURCES = pie_copyrelocs_test.cc
pie_copyrelocs_test_DEPENDENCIES = gcctestdir/ld pie_copyrelocs_shared_test.so
pie_copyrelocs_test_LDFLAGS = -Bgcctestdir/ -Wl,-R,. -pie
pie_copyrelocs_test_LDADD = pie_copyrelocs_shared_test.so
pie_copyrelocs_shared_test.o: pie_copyrelocs_shared_test.cc
$(CXXCOMPILE) -O2 -fpic -c -o $@ $<
pie_copyrelocs_shared_test.so: pie_copyrelocs_shared_test.o gcctestdir/ld
$(CXXLINK) -Bgcctestdir/ -shared pie_copyrelocs_shared_test.o
check_SCRIPTS += two_file_shared.sh
check_DATA += two_file_shared.dbg
MOSTLYCLEANFILES += two_file_shared.dbg

42
gold/testsuite/Makefile.in
View File

@ -181,7 +181,8 @@ check_PROGRAMS = $(am__EXEEXT_1) $(am__EXEEXT_2) $(am__EXEEXT_3) \
@GCC_TRUE@@NATIVE_LINKER_TRUE@ two_file_separate_shared_12_test \
@GCC_TRUE@@NATIVE_LINKER_TRUE@ two_file_separate_shared_21_test \
@GCC_TRUE@@NATIVE_LINKER_TRUE@ two_file_relocatable_test \
@GCC_TRUE@@NATIVE_LINKER_TRUE@ two_file_pie_test
@GCC_TRUE@@NATIVE_LINKER_TRUE@ two_file_pie_test \
@GCC_TRUE@@NATIVE_LINKER_TRUE@ pie_copyrelocs_test
# The nonpic tests will fail on platforms which can not put non-PIC
# code into shared libraries, so we just don't run them in that case.
@ -782,7 +783,8 @@ libgoldtest_a_OBJECTS = $(am_libgoldtest_a_OBJECTS)
@GCC_TRUE@@NATIVE_LINKER_TRUE@ two_file_separate_shared_12_test$(EXEEXT) \
@GCC_TRUE@@NATIVE_LINKER_TRUE@ two_file_separate_shared_21_test$(EXEEXT) \
@GCC_TRUE@@NATIVE_LINKER_TRUE@ two_file_relocatable_test$(EXEEXT) \
@GCC_TRUE@@NATIVE_LINKER_TRUE@ two_file_pie_test$(EXEEXT)
@GCC_TRUE@@NATIVE_LINKER_TRUE@ two_file_pie_test$(EXEEXT) \
@GCC_TRUE@@NATIVE_LINKER_TRUE@ pie_copyrelocs_test$(EXEEXT)
@FN_PTRS_IN_SO_WITHOUT_PIC_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@am__EXEEXT_9 = two_file_shared_1_nonpic_test$(EXEEXT) \
@FN_PTRS_IN_SO_WITHOUT_PIC_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@ two_file_shared_2_nonpic_test$(EXEEXT) \
@FN_PTRS_IN_SO_WITHOUT_PIC_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@ two_file_same_shared_nonpic_test$(EXEEXT) \
@ -1407,6 +1409,11 @@ permission_test_LDADD = $(LDADD)
permission_test_DEPENDENCIES = libgoldtest.a ../libgold.a \
../../libiberty/libiberty.a $(am__DEPENDENCIES_1) \
$(am__DEPENDENCIES_1) $(am__DEPENDENCIES_1)
@GCC_TRUE@@NATIVE_LINKER_TRUE@am_pie_copyrelocs_test_OBJECTS = \
@GCC_TRUE@@NATIVE_LINKER_TRUE@ pie_copyrelocs_test.$(OBJEXT)
pie_copyrelocs_test_OBJECTS = $(am_pie_copyrelocs_test_OBJECTS)
pie_copyrelocs_test_LINK = $(CXXLD) $(AM_CXXFLAGS) $(CXXFLAGS) \
$(pie_copyrelocs_test_LDFLAGS) $(LDFLAGS) -o $@
plugin_test_1_SOURCES = plugin_test_1.c
plugin_test_1_OBJECTS = plugin_test_1.$(OBJEXT)
plugin_test_1_LDADD = $(LDADD)
@ -1875,14 +1882,15 @@ SOURCES = $(libgoldtest_a_SOURCES) basic_pic_test.c basic_pie_test.c \
$(large_symbol_alignment_SOURCES) $(leb128_unittest_SOURCES) \
local_labels_test.c many_sections_r_test.c \
$(many_sections_test_SOURCES) $(object_unittest_SOURCES) \
permission_test.c plugin_test_1.c plugin_test_2.c \
plugin_test_3.c plugin_test_4.c plugin_test_5.c \
plugin_test_6.c plugin_test_7.c plugin_test_8.c \
plugin_test_tls.c $(protected_1_SOURCES) \
$(protected_2_SOURCES) $(relro_now_test_SOURCES) \
$(relro_script_test_SOURCES) $(relro_strip_test_SOURCES) \
$(relro_test_SOURCES) $(script_test_1_SOURCES) \
script_test_11.c $(script_test_2_SOURCES) script_test_3.c \
permission_test.c $(pie_copyrelocs_test_SOURCES) \
plugin_test_1.c plugin_test_2.c plugin_test_3.c \
plugin_test_4.c plugin_test_5.c plugin_test_6.c \
plugin_test_7.c plugin_test_8.c plugin_test_tls.c \
$(protected_1_SOURCES) $(protected_2_SOURCES) \
$(relro_now_test_SOURCES) $(relro_script_test_SOURCES) \
$(relro_strip_test_SOURCES) $(relro_test_SOURCES) \
$(script_test_1_SOURCES) script_test_11.c \
$(script_test_2_SOURCES) script_test_3.c \
$(searched_file_test_SOURCES) start_lib_test.c \
$(thin_archive_test_1_SOURCES) $(thin_archive_test_2_SOURCES) \
$(tls_phdrs_script_test_SOURCES) $(tls_pic_test_SOURCES) \
@ -2312,6 +2320,10 @@ LDADD = libgoldtest.a ../libgold.a ../../libiberty/libiberty.a $(LIBINTL) \
@GCC_TRUE@@NATIVE_LINKER_TRUE@two_file_relocatable_test_LDFLAGS = -Bgcctestdir/ -Wl,-R,.
@GCC_TRUE@@NATIVE_LINKER_TRUE@two_file_relocatable_test_LDADD = two_file_relocatable.o
@GCC_TRUE@@NATIVE_LINKER_TRUE@pie_copyrelocs_test_SOURCES = pie_copyrelocs_test.cc
@GCC_TRUE@@NATIVE_LINKER_TRUE@pie_copyrelocs_test_DEPENDENCIES = gcctestdir/ld pie_copyrelocs_shared_test.so
@GCC_TRUE@@NATIVE_LINKER_TRUE@pie_copyrelocs_test_LDFLAGS = -Bgcctestdir/ -Wl,-R,. -pie
@GCC_TRUE@@NATIVE_LINKER_TRUE@pie_copyrelocs_test_LDADD = pie_copyrelocs_shared_test.so
@FN_PTRS_IN_SO_WITHOUT_PIC_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@two_file_shared_1_nonpic_test_SOURCES = \
@FN_PTRS_IN_SO_WITHOUT_PIC_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@ two_file_test_2.cc two_file_test_main.cc
@ -3245,6 +3257,9 @@ object_unittest$(EXEEXT): $(object_unittest_OBJECTS) $(object_unittest_DEPENDENC
@NATIVE_LINKER_FALSE@permission_test$(EXEEXT): $(permission_test_OBJECTS) $(permission_test_DEPENDENCIES)
@NATIVE_LINKER_FALSE@ @rm -f permission_test$(EXEEXT)
@NATIVE_LINKER_FALSE@ $(LINK) $(permission_test_OBJECTS) $(permission_test_LDADD) $(LIBS)
pie_copyrelocs_test$(EXEEXT): $(pie_copyrelocs_test_OBJECTS) $(pie_copyrelocs_test_DEPENDENCIES)
@rm -f pie_copyrelocs_test$(EXEEXT)
$(pie_copyrelocs_test_LINK) $(pie_copyrelocs_test_OBJECTS) $(pie_copyrelocs_test_LDADD) $(LIBS)
@GCC_FALSE@plugin_test_1$(EXEEXT): $(plugin_test_1_OBJECTS) $(plugin_test_1_DEPENDENCIES)
@GCC_FALSE@ @rm -f plugin_test_1$(EXEEXT)
@GCC_FALSE@ $(LINK) $(plugin_test_1_OBJECTS) $(plugin_test_1_LDADD) $(LIBS)
@ -3635,6 +3650,7 @@ distclean-compile:
@AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/many_sections_test.Po@am__quote@
@AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/object_unittest.Po@am__quote@
@AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/permission_test.Po@am__quote@
@AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/pie_copyrelocs_test.Po@am__quote@
@AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/plugin_test_1.Po@am__quote@
@AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/plugin_test_2.Po@am__quote@
@AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/plugin_test_3.Po@am__quote@
@ -4202,6 +4218,8 @@ two_file_relocatable_test.log: two_file_relocatable_test$(EXEEXT)
@p='two_file_relocatable_test$(EXEEXT)'; $(am__check_pre) $(LOG_COMPILE) "$$tst" $(am__check_post)
two_file_pie_test.log: two_file_pie_test$(EXEEXT)
@p='two_file_pie_test$(EXEEXT)'; $(am__check_pre) $(LOG_COMPILE) "$$tst" $(am__check_post)
pie_copyrelocs_test.log: pie_copyrelocs_test$(EXEEXT)
@p='pie_copyrelocs_test$(EXEEXT)'; $(am__check_pre) $(LOG_COMPILE) "$$tst" $(am__check_post)
two_file_shared_1_nonpic_test.log: two_file_shared_1_nonpic_test$(EXEEXT)
@p='two_file_shared_1_nonpic_test$(EXEEXT)'; $(am__check_pre) $(LOG_COMPILE) "$$tst" $(am__check_post)
two_file_shared_2_nonpic_test.log: two_file_shared_2_nonpic_test$(EXEEXT)
@ -4805,6 +4823,10 @@ uninstall-am:
@GCC_TRUE@@NATIVE_LINKER_TRUE@two_file_pie_test: two_file_test_1_pie.o two_file_test_1b_pie.o \
@GCC_TRUE@@NATIVE_LINKER_TRUE@ two_file_test_2_pie.o two_file_test_main_pie.o gcctestdir/ld
@GCC_TRUE@@NATIVE_LINKER_TRUE@ $(CXXLINK) -Bgcctestdir/ -pie two_file_test_1_pie.o two_file_test_1b_pie.o two_file_test_2_pie.o two_file_test_main_pie.o
@GCC_TRUE@@NATIVE_LINKER_TRUE@pie_copyrelocs_shared_test.o: pie_copyrelocs_shared_test.cc
@GCC_TRUE@@NATIVE_LINKER_TRUE@ $(CXXCOMPILE) -O2 -fpic -c -o $@ $<
@GCC_TRUE@@NATIVE_LINKER_TRUE@pie_copyrelocs_shared_test.so: pie_copyrelocs_shared_test.o gcctestdir/ld
@GCC_TRUE@@NATIVE_LINKER_TRUE@ $(CXXLINK) -Bgcctestdir/ -shared pie_copyrelocs_shared_test.o
@GCC_TRUE@@NATIVE_LINKER_TRUE@two_file_shared.dbg: two_file_shared.so
@GCC_TRUE@@NATIVE_LINKER_TRUE@ $(TEST_READELF) -w $< >$@ 2>/dev/null
@FN_PTRS_IN_SO_WITHOUT_PIC_TRUE@@GCC_TRUE@@NATIVE_LINKER_TRUE@two_file_shared_1_nonpic.so: two_file_test_1.o gcctestdir/ld

6
gold/tilegx.cc
View File

@ -3758,7 +3758,8 @@ Target_tilegx<size, big_endian>::Scan::global(Symbol_table* symtab,
// Make a dynamic relocation if necessary.
if (gsym->needs_dynamic_reloc(Scan::get_reference_flags(r_type)))
{
if (gsym->may_need_copy_reloc())
if (!parameters->options().output_is_position_independent()
&& gsym->may_need_copy_reloc())
{
target->copy_reloc(symtab, layout, object,
data_shndx, output_section, gsym, reloc);
@ -3832,7 +3833,8 @@ Target_tilegx<size, big_endian>::Scan::global(Symbol_table* symtab,
// Make a dynamic relocation if necessary.
if (gsym->needs_dynamic_reloc(Scan::get_reference_flags(r_type)))
{
if (gsym->may_need_copy_reloc())
if (parameters->options().output_is_executable()
&& gsym->may_need_copy_reloc())
{
target->copy_reloc(symtab, layout, object,
data_shndx, output_section, gsym, reloc);

6
gold/x86_64.cc
View File

@ -2774,7 +2774,8 @@ Target_x86_64<size>::Scan::global(Symbol_table* symtab,
// Make a dynamic relocation if necessary.
if (gsym->needs_dynamic_reloc(Scan::get_reference_flags(r_type)))
{
if (gsym->may_need_copy_reloc())
if (!parameters->options().output_is_position_independent()
&& gsym->may_need_copy_reloc())
{
target->copy_reloc(symtab, layout, object,
data_shndx, output_section, gsym, reloc);
@ -2835,7 +2836,8 @@ Target_x86_64<size>::Scan::global(Symbol_table* symtab,
// Make a dynamic relocation if necessary.
if (gsym->needs_dynamic_reloc(Scan::get_reference_flags(r_type)))
{
if (gsym->may_need_copy_reloc())
if (parameters->options().output_is_executable()
&& gsym->may_need_copy_reloc())
{
target->copy_reloc(symtab, layout, object,
data_shndx, output_section, gsym, reloc);