[PATCH v2 15/31] arm64: SMP support

* Catalin Marinas [off-list ref] [120814 11:05]:

This patch adds SMP initialisation and spinlocks implementation for
AArch64. The spinlock support uses the new load-acquire/store-release
instructions to avoid explicit barriers. The architecture also specifies
that an event is automatically generated when clearing the exclusive
monitor state to wake up processors in WFE, so there is no need for an
explicit DSB/SEV instruction sequence. The SEVL instruction is used to
set the exclusive monitor locally as there is no conditional WFE and a
branch is more expensive.

Do we always have SMP hardware on arm64? Or are we going to need to
again add smp_on_up support later on?

Other than that:

Acked-by: Tony Lindgren <tony@atomide.com>