[ARM] Fix ld.so crash when built using Binutils 2.29

[Ramana Radhakrishnan]

On Wed, Jul 12, 2017 at 5:13 PM, Jiong Wang <jiong.wang@foss.arm.com> wrote:
> Hi,
>
>   There is bug report that ld.so in GLIBC 2.24 built by Binutils 2.29 will
> crash
> on arm-linux-gnueabihf.  This is confirmed, and the details is at:
>
>    https://sourceware.org/bugzilla/show_bug.cgi?id=21725.
>
>   And I could also reproduce this crash using GLIBC master.
>
>   As analyzed in the PR, the old code was with the assumption that assembler
> won't set bit0 of thumb function address if it comes from PC-relative
> instructions and the calculation can be finished during assembling.  This
> assumption however does not hold after PR gas/21458.
>
>   I think ARM backend in GLIBC should be fix to be more portable so it could
> work with various combinations of GLIBC and Binutils.
>
>   OK for master and backport to all release branches?

Has a combination of a binutils that did not have the fix for 21458 +
glibc with this patch been tested ?

Ramana
>
>
> 2017-07-12  Jiong Wang  <jiong.wang@arm.com>
>
>         * sysdeps/arm/dl-machine.h (elf_machine_load_address):  Also strip
> bit 0
>         of pcrel_address under Thumb mode.
>