[PATCH] PowerPC64: Add __private_ss field to TCB header

[Adhemerval Zanella]

Hi Uli, this patch is ok.


On 12-11-2013 19:19, Ulrich Weigand wrote:
> Hello,
>
> the TCB header on Intel contains a field __private_ss that is used
> to efficiently implement the -fsplit-stack GCC feature.
>
> In order to prepare for a possible future implementation of that
> feature on powerpc64, we'd like to reserve a similar field in
> the TCB header as well.  (It would be good if this went in with
> or before the ELFv2 patches to ensure that this field will be
> available always in the ELFv2 environment.)
>
> The field needs to be added at the front of tcbhead_t structure
> to avoid changing the ABI; see the recent discussion when adding
> the EBB fields.
>
> Tested on powerpc64-linux and powerpc64le-linux.
>
> OK for mainline?
>
> Bye,
> Ulrich
>
>
> nptl/ChangeLog:
>
> 2013-11-12  Ulrich Weigand  <Ulrich.Weigand@de.ibm.com>
>
> 	* sysdeps/powerpc/tls.h (tcbhead_t): Add __private_ss field.
>
> Index: glibc/nptl/sysdeps/powerpc/tls.h
> ===================================================================
> --- glibc.orig/nptl/sysdeps/powerpc/tls.h
> +++ glibc/nptl/sysdeps/powerpc/tls.h
> @@ -61,6 +61,8 @@ typedef union dtv
>     are private.  */
>  typedef struct
>  {
> +  /* GCC split stack support.  */
> +  void *__private_ss;
>    /* Reservation for the Event-Based Branching ABI.  */
>    uintptr_t ebb_handler;
>    uintptr_t ebb_ctx_pointer;