powerpc/64s: relocation, register save fixes for system reset interrupt

[Michael Ellerman]

On Thu, 2016-13-10 at 02:17:14 UTC, Nicholas Piggin wrote:
> This patch does a couple of things. First of all, powernv immediately
> explodes when running a relocated kernel, because the system reset
> exception for handling sleeps does not do correct relocated branches.
> 
> Secondly, the sleep handling code trashes the condition and cfar
> registers, which we would like to preserve for debugging purposes (for
> non-sleep case exception).
> 
> This patch changes the exception to use the standard format that saves
> registers before any tests or branches are made. It adds the test for
> idle-wakeup as an "extra" to break out of the normal exception path.
> Then it branches to a relocated idle handler that calls the various
> idle handling functions.
> 
> After this patch, POWER8 CPU simulator now boots powernv kernel that is
> running at non-zero.
> 
> Cc: Balbir Singh <bsingharora at gmail.com>
> Cc: Shreyas B. Prabhu <shreyas at linux.vnet.ibm.com>
> Cc: Gautham R. Shenoy <ego at linux.vnet.ibm.com>
> Signed-off-by: Nicholas Piggin <npiggin at gmail.com>
> Acked-by: Gautham R. Shenoy <ego at linux.vnet.ibm.com>
> Acked-by: Balbir Singh <bsingharora at gmail.com>

Applied to powerpc fixes, thanks.

https://git.kernel.org/powerpc/c/fb479e44a9e240a23c2d208c2ace23

cheers