[POWERPC] Make emergency stack safe for current_thread_info() use
[POWERPC] Make emergency stack safe for current_thread_info() use

The current_thread_info() macro, used by preempt_count(), assumes the
base address and size of the stack are THREAD_SIZE aligned.

The emergency stack currently isn't either of these things, which
could potentially cause problems anytime we're running on the
emergency stack.  That includes when we detect a bad kernel stack
pointer, and also during early_setup_secondary().

Signed-off-by: Michael Ellerman <17b9e1c64588c7fa6419b4d29dc1f4426279ba01@ellerman.id.au>
Signed-off-by: Paul Mackerras <19a0ba370c443ba08d20b5061586430ab449ee8c@samba.org>

KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas