[PATCH v2 05/12] powerpc/dexcr: Support userspace ROP protection

[Russell Currey]

On Thu, 2023-03-30 at 16:50 +1100, Benjamin Gray wrote:
> The ISA 3.1B hashst and hashchk instructions use a per-cpu SPR
> HASHKEYR
> to hold a key used in the hash calculation. This key should be
> different
> for each process to make it harder for a malicious process to
> recreate
> valid hash values for a victim process.
> 
> Add support for storing a per-thread hash key, and setting/clearing
> HASHKEYR appropriately.
> 
> Signed-off-by: Benjamin Gray <bgray at linux.ibm.com>

Reviewed-by: Russell Currey <ruscur at russell.cc>