S390: Add support for vdso getcpu symbol.

[Stefan Liebler]

ping

Any objection? Otherwise, I'll commit this patch.

On 04/29/2016 09:42 AM, Stefan Liebler wrote:
> Hi,
>
> This patch adds support for symbol __kernel_getcpu in vDSO,
> which is available with kernel 4.5.
> Now sched_getcpu is using this symbol if available in mapped vDSO
> by defining macro HAVE_GETCPU_VSYSCALL. If not available at runtime,
> the former syscall is used.
>
> Bye
> Stefan
>
> ChangeLog:
>
>      * sysdeps/unix/sysv/linux/s390/init-first.c:
>      Add VDSO_SYMBOL(getcpu).
>      (_libc_vdso_platform_setup): Initialize VDSO_SYMBOL(getcpu).
>      * sysdeps/unix/sysv/linux/s390/libc-vdso.h:
>      Add VDSO_SYMBOL(getcpu).
>      * sysdeps/unix/sysv/linux/s390/s390-32/sysdep.h:
>      New define HAVE_GETCPU_VSYSCALL.
>      * sysdeps/unix/sysv/linux/s390/s390-64/sysdep.h: Likewise.