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

[Greg KH <greg@kroah.com>]

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 <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=822
> Signed-off-by: James Morse <james.morse@arm.com>
> Cc: <stable@vger.kernel.org> #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