7 which corresponds to WSTATE_KMIX in OpenSolaris whenever calling into
it which totally screws us even when restoring %wstate afterwards as
spill/fill traps can happen while in OFW. The rather hackish OpenBSD
approach of just setting the equivalent of WSTATE_KERNEL to 7 also is
no option as we treat %wstate as a bit field. So in order to deal with
this problem actually implement spill/fill handlers for %wstate 7 which
just act as the WSTATE_KERNEL ones except of theoretically also handling
32-bit, turn off interrupts completely so we don't even take IPIs while
in OFW which should ensure we only take spill/fill traps at most and
restore %wstate after calling into OFW once we have taken over the trap
table. While at it, actually set WSTATE_{,PROM}_KMIX before calling into
OFW just like OpenSolaris does, which should at least help testing this
change on non-V1280.
- Remove comments referring to the %wstate usage in BSD/OS.
- Remove the no longer used RSF_ALIGN_RETRY macro.
- Correct some trap table addresses in comments.
- Ensure %wstate is set to WSTATE_KERNEL when taking over the trap table.
- Ensure PSTATE_AM is off when entering or exiting to OFW as well as that
interrupts are also completely off when exiting to OFW as the firmware
trap table shouldn't be used to handle our interrupts.
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