[Bug ld/18167] [2.25 regression] binutils fails to link gmp on ARM32

[cvs-commit at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=18167

--- Comment #6 from cvs-commit at gcc dot gnu.org <cvs-commit at gcc dot 
gnu.org> ---
The binutils-2_25-branch branch has been updated by Alan Modra
<address@hidden>:

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=12aca65e0f9148bf136a9f4cfc2187aa485a143a

commit 12aca65e0f9148bf136a9f4cfc2187aa485a143a
Author: Alan Modra <address@hidden>
Date:   Fri Mar 27 15:41:05 2015 +1030

    Relax PR 15228 protected visibility restriction

    Allows .dynbss copy of shared library protected visibility variables
    if they are read-only.

    To recap: Copying a variable from a shared library into an executable's
    .dynbss is an old hack invented for non-PIC executables, to avoid the
    text relocations you'd otherwise need to access a shared library
    variable.  This works with ELF shared libraries because global
    symbols can be overridden.  The trouble is that protected visibility
    symbols can't be overridden.  A shared library will continue to access
    it's own protected visibility variable while the executable accesses a
    copy.  If either the shared library or the executable updates the
    value then the copy diverges from the original.  This is wrong since
    there is only one definition of the variable in the application.

    So I made the linker report an error on attempting to copy protected
    visibility variables into .dynbss.  However, you'll notice the above
    paragraph contains an "If".  An application that does not modify the
    variable value remains correct even though two copies of the variable
    exist.  The linker can detect this situation if the variable was
    defined in a read-only section.

        PR ld/15228
        PR ld/18167
        * elflink.c (elf_merge_st_other): Add "sec" parameter.  Don't set
        protected_def when symbol section is read-only.  Adjust all calls.
        * elf-bfd.h (struct elf_link_hash_entry): Update protected_def comment.

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