Since we do not plan to exit, use cpu_unwind_state_data
and extract exactly the data requested.
This is a bug fix, in that we no longer clobber dflag.
Consider:
l.j L2 // branch
l.mfspr r1, ppc // delay
L1: boom
L2: l.lwa r3, (r4)
Here, dflag would be set by cpu_restore_state (because that is the current
state of the cpu), but but not cleared by tb_stop on exiting the TB
(because DisasContext has recorded the current value as zero).
The next TB begins at L2 with dflag incorrectly set. If the load has a
tlb miss, then the exception will be delivered as per a delay slot:
with DSX set in the status register and PC decremented (delay slots
restart by re-executing the branch). This will cause the return from
interrupt to go to L1, and boom!
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
cc30dc441b