[stable:PATCH 1/2] arm64: kernel: Save and restore addr_limit on exception entry

On Fri, Aug 12, 2016 at 07:11:19PM +0100, James Morse wrote:

commit e19a6ee2460bdd0d0055a6029383422773f9999a 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 <redacted>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Will Deacon <redacted>
[ 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=822
Signed-off-by: James Morse <james.morse@arm.com>
Cc: <redacted> #4.1

Fails to apply to 4.4-stable, can you provide a backport for both of
these to that tree if you want them there?

thanks,

greg k-h