[x86] Resolve non-PIC undefweak symbols in executable

For i386 and x86-64, non-PIC references to undefined weak symbols are
resolved without dynamic relocation when creating executable.  Resolved
undefined weak symbols are removed from the dynamic symbol table in
executable.  One exception is on i386, we need resolved undefined weak
symbols in the dynamic symbol table in PIE if input relocatable files
contain branchs without PLT so that we can branch to 0 with dynamic
relocation in text section.

This makes behaviors of dynamic executable and position independent
executable predictable with mixed PIC and non-PIC references to undefined
weak symbols.  If all references to undefined weak symbols are PIC,
dynamic relocations against undefined weak symbols will be generated
in executable unless -z nodynamic-undefined-weak is passed to linker.

bfd/

	PR ld/19636
	PR ld/19704
	PR ld/19719
	* elf32-i386.c (UNDEFINED_WEAK_RESOLVED_TO_ZERO): New.
	(elf_i386_link_hash_entry): Add has_got_reloc and
	has_non_got_reloc.
	(elf_i386_link_hash_table): Add interp.
	(elf_i386_link_hash_newfunc): Initialize has_got_reloc and
	has_non_got_reloc.
	(elf_i386_copy_indirect_symbol): Copy has_got_reloc and
	has_non_got_reloc.
	(elf_i386_check_relocs): Set has_got_reloc and has_non_got_reloc.
	(elf_i386_fixup_symbol): New function.
	(elf_i386_pie_finish_undefweak_symbol): Likewise.
	(elf_i386_allocate_dynrelocs): Don't allocate space for dynamic
	relocations and discard relocations against resolved undefined
	weak symbols in executable.  Don't make resolved undefined weak
	symbols in executable dynamic.  Keep dynamic non-GOT/non-PLT
	relocation against undefined weak symbols in PIE.
	(elf_i386_size_dynamic_sections): Set interp to .interp section.
	(elf_i386_relocate_section): Don't generate dynamic relocations
	against resolved undefined weak symbols in PIE, except for
	R_386_PC32.
	(elf_i386_finish_dynamic_symbol): Keep PLT/GOT entries without
	dynamic PLT/GOT relocations for resolved undefined weak symbols.
	Don't generate dynamic relocation against resolved undefined weak
	symbol in executable.
	(elf_i386_finish_dynamic_sections): Call
	elf_i386_pie_finish_undefweak_symbol on all symbols in PIE.
	(elf_backend_fixup_symbol): New.
	* elf64-x86-64.c (UNDEFINED_WEAK_RESOLVED_TO_ZERO): New.
	(elf_x86_64_link_hash_entry): Add has_got_reloc and
	has_non_got_reloc.
	(elf_x86_64_link_hash_table): Add interp.
	(elf_x86_64_link_hash_newfunc): Initialize has_got_reloc and
	has_non_got_reloc.
	(elf_x86_64_copy_indirect_symbol): Copy has_got_reloc and
	has_non_got_reloc.
	(elf_x86_64_check_relocs): Set has_got_reloc and
	has_non_got_reloc.
	(elf_x86_64_fixup_symbol): New function.
	(elf_x86_64_pie_finish_undefweak_symbol): Likewise.
	(elf_x86_64_allocate_dynrelocs): Don't allocate space for dynamic
	relocations and discard relocations against resolved undefined
	weak symbols in executable.  Don't make resolved undefined weak
	symbols in executable dynamic.
	(elf_x86_64_size_dynamic_sections): Set interp to .interp section.
	(elf_x86_64_relocate_section): Check relocation overflow for
	dynamic relocations against unresolved weak undefined symbols.
	Don't generate dynamic relocations against resolved weak
	undefined symbols in PIE.
	(elf_x86_64_finish_dynamic_symbol): Keep PLT/GOT entries without
	dynamic PLT/GOT relocations for resolved undefined weak symbols.
	Don't generate dynamic relocation against resolved undefined weak
	symbol in executable.
	(elf_x86_64_finish_dynamic_sections): Call
	elf_x86_64_pie_finish_undefweak_symbol on all symbols in PIE.
	(elf_backend_fixup_symbol): New.

include/

	PR ld/19636
	PR ld/19704
	PR ld/19719
	* bfdlink.h (bfd_link_info): Add dynamic_undefined_weak.

ld/

	PR ld/19636
	PR ld/19704
	PR ld/19719
	* Makefile.am (ELF_X86_DEPS): Add dynamic_undefined_weak.sh.
	* Makefile.in: Regenerated.
	* NEWS: Mention -z nodynamic-undefined-weak.
	* ld.texinfo: Document -z nodynamic-undefined-weak.
	* ldmain.c (main): Initialize dynamic_undefined_weak to -1.
	* emulparams/dynamic_undefined_weak.sh: New file.
	* emulparams/elf32_x86_64.sh: Source dynamic_undefined_weak.sh.
	* emulparams/elf_i386.sh: Likewise.
	* emulparams/elf_i386_be.sh: Likewise.
	* emulparams/elf_i386_chaos.sh: Likewise.
	* emulparams/elf_i386_ldso.sh: Likewise.
	* emulparams/elf_i386_vxworks.sh: Likewise.
	* emulparams/elf_iamcu.sh: Likewise.
	* emulparams/elf_k1om.sh: Likewise.
	* emulparams/elf_l1om.sh: Likewise.
	* emulparams/elf_x86_64.sh: Likewise.
	* emulparams/extern_protected_data.sh (PARSE_AND_LIST_OPTIONS):
	Append.
	(PARSE_AND_LIST_ARGS_CASE_Z): Likewise.
	* testsuite/ld-elf/pr19719a.c: New file.
	* testsuite/ld-elf/pr19719b.c: Likewise.
	* testsuite/ld-elf/pr19719c.c: Likewise.
	* testsuite/ld-elf/pr19719d.c: Likewise.
	* testsuite/ld-i386/pr19636-1.s: Likewise.
	* testsuite/ld-i386/pr19636-1a.d: Likewise.
	* testsuite/ld-i386/pr19636-1b.d: Likewise.
	* testsuite/ld-i386/pr19636-1c.d: Likewise.
	* testsuite/ld-i386/pr19636-1d-nacl.d: Likewise.
	* testsuite/ld-i386/pr19636-1d.d: Likewise.
	* testsuite/ld-i386/pr19636-1e.d: Likewise.
	* testsuite/ld-i386/pr19636-1f.d: Likewise.
	* testsuite/ld-i386/pr19636-1g.d: Likewise.
	* testsuite/ld-i386/pr19636-1h.d: Likewise.
	* testsuite/ld-i386/pr19636-1i.d: Likewise.
	* testsuite/ld-i386/pr19636-2.s: Likewise.
	* testsuite/ld-i386/pr19636-2a.d: Likewise.
	* testsuite/ld-i386/pr19636-2b.d: Likewise.
	* testsuite/ld-i386/pr19636-2c-nacl.d: Likewise.
	* testsuite/ld-i386/pr19636-2c.d: Likewise.
	* testsuite/ld-i386/pr19636-2d-nacl.d: Likewise.
	* testsuite/ld-i386/pr19636-2d.d: Likewise.
	* testsuite/ld-i386/pr19636-2e-nacl.d: Likewise.
	* testsuite/ld-i386/pr19636-2e.d: Likewise.
	* testsuite/ld-i386/pr19636-3.s: Likewise.
	* testsuite/ld-i386/pr19636-3a.d: Likewise.
	* testsuite/ld-i386/pr19636-3b.d: Likewise.
	* testsuite/ld-i386/pr19636-3c.d: Likewise.
	* testsuite/ld-i386/pr19636-3d.d: Likewise.
	* testsuite/ld-i386/pr19636-3e.d: Likewise.
	* testsuite/ld-i386/pr19636-3f.d: Likewise.
	* testsuite/ld-i386/pr19636-3g.d: Likewise.
	* testsuite/ld-i386/pr19636-4.s: Likewise.
	* testsuite/ld-i386/pr19636-4a.d: Likewise.
	* testsuite/ld-i386/pr19636-4b.d: Likewise.
	* testsuite/ld-i386/pr19636-4c.d: Likewise.
	* testsuite/ld-i386/pr19636-4d.d: Likewise.
	* testsuite/ld-i386/pr19704.out: Likewise.
	* testsuite/ld-i386/pr19704a.c: Likewise.
	* testsuite/ld-i386/pr19704b.c: Likewise.
	* testsuite/ld-x86-64/pr19636-1.s: Likewise.
	* testsuite/ld-x86-64/pr19636-1a.d: Likewise.
	* testsuite/ld-x86-64/pr19636-1b.d: Likewise.
	* testsuite/ld-x86-64/pr19636-1c.d: Likewise.
	* testsuite/ld-x86-64/pr19636-1d.d: Likewise.
	* testsuite/ld-x86-64/pr19636-1e.d: Likewise.
	* testsuite/ld-x86-64/pr19636-1f.d: Likewise.
	* testsuite/ld-x86-64/pr19636-1g.d: Likewise.
	* testsuite/ld-x86-64/pr19636-2.s: Likewise.
	* testsuite/ld-x86-64/pr19636-2a.d: Likewise.
	* testsuite/ld-x86-64/pr19636-2b.d: Likewise.
	* testsuite/ld-x86-64/pr19636-2c.d: Likewise.
	* testsuite/ld-x86-64/pr19636-2d-nacl.d: Likewise.
	* testsuite/ld-x86-64/pr19636-2d.d: Likewise.
	* testsuite/ld-x86-64/pr19636-2e.d: Likewise.
	* testsuite/ld-x86-64/pr19636-2f.d: Likewise.
	* testsuite/ld-x86-64/pr19636-2g.d: Likewise.
	* testsuite/ld-x86-64/pr19636-2h.d: Likewise.
	* testsuite/ld-x86-64/pr19636-2i.d: Likewise.
	* testsuite/ld-x86-64/pr19636-3.s: Likewise.
	* testsuite/ld-x86-64/pr19636-3a.d: Likewise.
	* testsuite/ld-x86-64/pr19636-3b.d: Likewise.
	* testsuite/ld-x86-64/pr19636-3c.d: Likewise.
	* testsuite/ld-x86-64/pr19636-3d.d: Likewise.
	* testsuite/ld-x86-64/pr19704.out: Likewise.
	* testsuite/ld-x86-64/pr19704a.c: Likewise.
	* testsuite/ld-x86-64/pr19704b.c: Likewise.
	* testsuite/ld-elf/shared.exp (mix_pic_and_non_pic): New.
	Run mix_pic_and_non_pic.
	* testsuite/ld-i386/i386.exp (undefined_weak): New.
	Run undefined_weak and PR ld/19636 tests.
	* testsuite/ld-x86-64/x86-64.exp: Likewise.
	* testsuite/ld-x86-64/pr13082-3b.d: Updated.
	* testsuite/ld-x86-64/pr13082-4b.d: Likewise.

2 files changed, 11 insertions, 0 deletions

diff --git a/include/ChangeLog b/include/ChangeLog
index f9e56e244df..ae4d7ff8949 100644
--- a/include/ChangeLog
+++ b/include/ChangeLog
@@ -1,3 +1,10 @@
+2016-02-26  H.J. Lu  <hongjiu.lu@intel.com>
+
+	PR ld/19636
+	PR ld/19704
+	PR ld/19719
+	* bfdlink.h (bfd_link_info): Add dynamic_undefined_weak.
+
 2016-02-19  Matthew Wahab  <matthew.wahab@arm.com>
 	    Jiong Wang  <jiong.wang@arm.com>
 
diff --git a/include/bfdlink.h b/include/bfdlink.h
index 9b849aa761e..860811c2a78 100644
--- a/include/bfdlink.h
+++ b/include/bfdlink.h
@@ -542,6 +542,10 @@ struct bfd_link_info
      backend to decide.  */
   int extern_protected_data;
 
+  /* > 0 to treat undefined weak symbol in the executable as dynamic,
+     requiring dynamic relocation.  */
+  int dynamic_undefined_weak;
+
   /* Non-zero if auto-import thunks for DATA items in pei386 DLLs
      should be generated/linked against.  Set to 1 if this feature
      is explicitly requested by the user, -1 if enabled by default.  */