kasan, arm64: fix up fault handling logic

Right now arm64 fault handling code removes pointer tags from addresses
covered by TTBR0 in faults taken from both EL0 and EL1, but doesn't do
that for pointers covered by TTBR1.

This patch adds two helper functions is_ttbr0_addr() and is_ttbr1_addr(),
where the latter one accounts for the fact that TTBR1 pointers might be
tagged when tag-based KASAN is in use, and uses these helper functions to
perform pointer checks in arch/arm64/mm/fault.c.

Link: http://lkml.kernel.org/r/3f349b0e9e48b5df3298a6b4ae0634332274494a.1544099024.git.andreyknvl@google.com


Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Suggested-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>