commit e19a6ee2 upstream.

If we take an exception while at EL1, the exception handler inherits
the original context's addr_limit value. To be consistent always reset
addr_limit and PSTATE.UAO on (re-)entry to EL1. This prevents accidental
re-use of the original context's addr_limit.

Based on a similar patch for arm from Russell King.
Acked-by: Will Deacon <will.deacon@arm.com>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
[ backport to stop perf misusing inherited addr_limit.
  Removed code interacting with UAO and the irqstack ]
Link: https://bugs.chromium.org/p/project-zero/issues/detail?id=822Signed-off-by: James Morse <james.morse@arm.com>
Cc: <stable@vger.kernel.org> #4.1
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>