[RFC PATCH v3 04/12] Validate r1 value before going to host kernel in virtual mode.

[Benjamin Herrenschmidt]

On Mon, 2013-09-09 at 15:29 +1000, Paul Mackerras wrote:
> Are we guaranteed that Sapphire will keep the stack pointer positive
> at all times?  (More a question for Ben H than you.)

Good point, we *might* eventually set the top bit..

Ben.