Powerpc64: Add the facility unavailable trap subsystem

[breno.leitao_gmail.com]

Summary

This code adds the basic infrastructure for the facility subsystem. A facility
trap is raised when an unavailable instruction is executed. One example is
executing a Hardware Transactional Memory instruction while the MSR[TM] is
disabled. In the past, there was a specific interrupt for it (FP, VEC), but the
new instructions seem to be multiplexed on this facility interrupt.

The root cause of the trap is provided on Facility Status and Control Register
(FSCR) register.

[jhibbits]

sys/powerpc/include/facility.h

1 ↗

(On Diff #39888)

I would put the definitions from this header into spr.h under the SPR_FSCR, like other SPR bits.

sys/powerpc/powerpc/trap.c

301

Don't forget the break; here, otherwise it falls through.

[breno.leitao_gmail.com]

hi Justin, thanks for the review. I will work on a v2 patchset.

sys/powerpc/include/facility.h

1 ↗

(On Diff #39888)

ok!

sys/powerpc/powerpc/trap.c

301

In fact, I was expecting it to fall through, execute the EXC_HEA code and return the SIGILL, but I think it will be better if I split and break both, and return SIGILL in the two cases.

[breno.leitao_gmail.com]

Patchset v2. Changes as requested by Justin (Thanks!):

• Move the SPR_FSCR definitions to spr.h
• Split the code between EXC_FAC and EXC_HEA.