[Bug ld/19636] -pie changes program behavior and generate unnecessary dynamic symbols.

[cvs-commit at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=19636

--- Comment #1 from cvs-commit at gcc dot gnu.org <cvs-commit at gcc dot 
gnu.org> ---
The master branch has been updated by H.J. Lu <address@hidden>:

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=aec6b87e0b66d707ead62ca40d220ee78b4cf5a5

commit aec6b87e0b66d707ead62ca40d220ee78b4cf5a5
Author: H.J. Lu <address@hidden>
Date:   Fri Feb 26 04:16:15 2016 -0800

    [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.

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