Executing a supervisor-level instruction in user mode is supposed to
cause a program exception to occur.
The following supervisor instructions are present:
- dcbi
- mfmsr
- mfspr
- mfsr
- mfsrin
- mtmsr
- mtspr
- mtsr
- mtsrin
- rfi
- tlbie
- tlbsync
In 0337ca116a checks within mfspr and
mtspr were added. This change adds the trivial checks to the other
instructions.