ARM: smp: store current pointer in TPIDRURO register if available

Use the user space TLS register TPIDRURO to keep the 'current' pointer
while running in the kernel. This removes the need to access it via
thread_info, which is located at the base of the stack, but will be
moved out of there in a subsequent patch.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
13 files changed