Re: RFC: PATCHES: Properly handle reference to protected data on x86

["H.J. Lu" <hjl dot tools at gmail dot com>]

On Thu, Mar 5, 2015 at 6:39 AM, H.J. Lu <hjl.tools@gmail.com> wrote:
> On Wed, Mar 4, 2015 at 3:26 PM, H.J. Lu <hjl.tools@gmail.com> wrote:
>> Protected symbol means that it can't be pre-emptied.  It
>> doesn't mean its address won't be external.  This is true
>> for pointer to protected function.  With copy relocation,
>> address of protected data defined in the shared library may
>> also be external.  We only know that for sure at run-time.
>> Here are patches for glibc, binutils and GCC to handle it
>> properly.
>>
>> Any comments?
>
> This is the binutils patch I checked in.  It basically reverted
> the change for
>
> https://sourceware.org/bugzilla/show_bug.cgi?id=15228
>
> on x86.  Copy relocations against protected symbols should
> work.
>
> --
> H.J.
> ---
> bfd/
>
> PR ld/pr15228
> PR ld/pr17709
> * elf-bfd.h (elf_backend_data): Add extern_protected_data.
> * elf32-i386.c (elf_backend_extern_protected_data): New.
> Defined to 1.
> * elf64-x86-64.c (elf_backend_extern_protected_data): Likewise.
> * elflink.c (_bfd_elf_adjust_dynamic_copy): Don't error on
> copy relocs against protected symbols if extern_protected_data
> is true.
> (_bfd_elf_symbol_refs_local_p): Don't return true on protected
> non-function symbols if extern_protected_data is true.
> * elfxx-target.h (elf_backend_extern_protected_data): New.
> Default to 0.
> (elfNN_bed): Initialize extern_protected_data with
> elf_backend_extern_protected_data.
>
> ld/testsuite/
>
> PR ld/pr15228
> PR ld/pr17709
> * ld-i386/i386.exp (i386tests): Add a test for PR ld/17709.
> * ld-i386/pr17709-nacl.rd: New file.
> * ld-i386/pr17709.rd: Likewise.
> * ld-i386/pr17709a.s: Likewise.
> * ld-i386/pr17709b.s: Likewise.
> * ld-i386/protected3.d: Updated.
> * ld-i386/protected3.s: Likewise.
> * ld-x86-64/pr17709-nacl.rd: New file.
> * ld-x86-64/pr17709.rd: Likewise.
> * ld-x86-64/pr17709a.s: Likewise.
> * ld-x86-64/pr17709b.s: Likewise.
> * ld-x86-64/protected3.d: Updated.
> * ld-x86-64/protected3.s: Likewise.
> * ld-x86-64/x86-64.exp (x86_64tests): Add a test for PR ld/17709.

I back ported it to 2.25 branch.

-- 
H.J.