PR 12372 points out a problem in gold: if an STT_GNU_IFUNC symbol is
defined with a function that calls other functions through the PLT, then
it is essential that the dynamic linker prepare the PLT entries before
it invokes the function for the STT_GNU_IFUNC symbol.  The GNU linker
does this by simply putting all IRELATIVE relocs after all JUMP_SLOT
relocs.  This patch implements the same approach in gold.  Committed to
mainline.

Ian


2011-07-08  Ian Lance Taylor  <iant@google.com>

	PR gold/12372
	* target.h (Target::plt_address_for_global): New function.
	(Target::plt_address_for_local): New function.
	(Target::plt_section_for_global): Remove.
	(Target::plt_section_for_local): Remove.
	(Target::do_plt_address_for_global): New virtual function.
	(Target::do_plt_address_for_local): New virtual function.
	(Target::do_plt_section_for_global): Remove.
	(Target::do_plt_section_for_local): Remove.
	(Target::register_global_plt_entry): Add Symbol_table and Layout
	parameters.
	* output.cc (Output_data_got::Got_entry::write): Use
	plt_address_for_global and plt_address_for_local.
	* layout.cc (Layout::add_target_dynamic_tags): Use size and
	address of output section.
	* i386.cc (class Output_data_plt_i386): Add irelative_rel_,
	got_irelative_, and irelative_count_ fields.  Update
	declarations.
	(Output_data_plt_i386::has_irelative_section): New function.
	(Output_data_plt_i386::entry_count): Add irelative_count_.
	(Output_data_plt_i386::set_final_data_size): Likewise.
	(class Target_i386): Add got_irelative_ and rel_irelative_
	fields.  Update declarations.
	(Target_i386::Target_i386): Initialize new fields.
	(Target_i386::do_plt_address_for_global): New function replacing
	do_plt_section_for_global.
	(Target_i386::do_plt_address_for_local): New function replacing
	do_plt_section_for_local.
	(Target_i386::got_section): Create got_irelative_.
	(Target_i386::rel_irelative_section): New function.
	(Output_data_plt_i386::Output_data_plt_i386): Initialize new
	fields.  Don't define __rel_iplt_{start,end}.
	(Output_data_plt_i386::add_entry): Add symtab and layout
	parameters.  Change all callers.  Use different PLT and GOT for
	IFUNC symbols.
	(Output_data_plt_i386::add_local_ifunc_entry): Add symtab and
	layout parameters.  Change all callers.  Use different PLT and
	GOT.
	(Output_data_plt_i386::rel_tls_desc): Fix formatting.
	(Output_data_plt_i386::rel_irelative): New function.
	(Output_data_plt_i386::address_for_global): New function.
	(Output_data_plt_i386::address_for_local): New function.
	(Output_data_plt_i386::do_write): Write out IRELATIVE area.  Use
	IRELATIVE GOT when changing IFUNC GOT entries.
	(Target_i386::Scan::global): Use IRELATIVE GOT for IRELATIVE
	reloc.
	(Target_i386::do_finalize_sections): Create the __rel_iplt symbols
	if we didn't create an IRELATIVE GOT.
	(Target_i386::Relocate::relocate): Use plt_address_for_global and
	plt_address_for_local.
	(Target_i386::do_dynsym_value): Use plt_address_for_global.
	* x86_64.cc (class Output_data_plt_x86_64): Add irelative_rel_,
	got_irelative_, and irelative_count_ fields.  Update
	declarations.
	(Output_data_plt_x86_64::Output_data_plt_x86_64) [both versions]:
	Initialize new fields.  Remove symtab parameter.  Change all
	callers.
	(Output_data_plt_x86_64::get_tlsdesc_plt_offset): Add
	irelative_count_.
	(Output_data_plt_x86_64::has_irelative_section): New function.
	(Output_data_plt_x86_64::entry_count): Add irelative_count_.
	(class Target_x86_64): Add got_irelative_ and rel_irelative_
	fields.  Update declarations.
	(Target_x86_64::Target_x86_64): Initialize new fields.
	(Target_x86_64::do_plt_address_for_global): New function replacing
	do_plt_section_for_global.
	(Target_x86_64::do_plt_address_for_local): New function replacing
	do_plt_section_for_local.
	(Target_x86_64::got_section): Create got_irelative_.
	(Target_x86_64::rela_irelative_section): New function.
	(Output_data_plt_x86_64::init): Remove symtab parameter.  Change
	all callers.  Don't create __rel_iplt_{start,end}.
	(Output_data_plt_x86_64::add_entry): Add symtab and layout
	parameters.  Change all callers.  Use different PLT and GOT for
	IFUNC symbols.
	(Output_data_plt_x86_64::add_local_ifunc_entry): Add symtab and
	layout parameters.  Change all callers.  Use different PLT and
	GOT.
	(Output_data_plt_x86_64::add_relocation): Add symtab and layout
	parameters.  Change all callers.  Use different PLT and GOT for
	IFUNC symbols.
	(Output_data_plt_x86_64::rela_tlsdesc): Fix formatting.
	(Output_data_plt_x86_64::rela_irelative): New function.
	(Output_data_plt_x86_64::address_for_global): New function.
	(Output_data_plt_x86_64::address_for_local): New function.
	(Output_data_plt_x86_64::set_final_data_size): Likewise.
	(Output_data_plt_x86_64::do_write): Write out IRELATIVE area.
	(Target_x86_64::init_got_plt_for_update): Create got_irelative_.
	(Target_x86_64::register_global_plt_entry): Add symtab and layout
	parameters.
	(Target_x86_64::Scan::global): Use IRELATIVE GOT for IRELATIVE
	reloc.
	(Target_x86_64::do_finalize_sections): Create the __rela_iplt
	symbols if we didn't create an IRELATIVE GOT.
	(Target_x86_64::Relocate::relocate): Use plt_address_for_global and
	plt_address_for_local.
	(Target_x86_64::do_dynsym_value): Use plt_address_for_global.
	* testsuite/ifuncvar1.c: New test file.
	* testsuite/ifuncvar2.c: New test file.
	* testsuite/ifuncvar3.c: New test file.
	* testsuite/Makefile.am (check_PROGRAMS): Add ifuncvar.
	(ifuncvar1_pic.o, ifuncvar2_pic.o, ifuncvar.so): New targets.
	(ifuncvar_SOURCES, ifuncvar_DEPENDENCIES): New variables.
	(ifuncvar_LDFLAGS, ifuncvar_LDADD): New variables.
	* testsuite/Makefile.in: Rebuild.