[PATCH] powerpc: Fix tabort usage in syscalls

[Steven Munroe]

On Fri, 2015-08-07 at 09:31 -0500, Paul E. Murphy wrote:
> Fix usage of tabort in generated syscalls.  r0 has special meaning
> when used with this instruction, thus it will not generate
> persistent errors, nor return an error code.  This mitigates poor
> CPU usage when performing elided critical sections.
> 
> Additionally, transactions should be aborted when entering a user
> invoked syscall.  Otherwise the results of the transaction may be
> undefined.
> 
> 2015-08-03  Paul E. Murphy  <murphyp@linux.vnet.ibm.com>
> 
> 	* sysdeps/powerpc/powerpc32/sysdep.h (ABORT_TRANSACTION): Use
> 	register other than r0 for tabort, it has special meaning.
> 	* sysdeps/powerpc/powerpc64/sysdep.h (ABORT_TRANSACTION): Likewise
> 	* sysdeps/unix.sysv/linux/powerpc/syscall.S (syscall): Abort
> 	transaction before starting syscall.
> ---

LGTM and require for reliable function, Please apply