[PATCH 1/2] powerpc/interrupt: Refactor interrupt_exit_user_prepare() and syscall_exit_prepare()

[Nicholas Piggin]

Excerpts from Christophe Leroy's message of May 14, 2021 6:28 pm:
> Last part of interrupt_exit_user_prepare() and syscall_exit_prepare()
> are identical.
> 
> Create a __interrupt_exit_user_prepare() function that is called by
> both.
> 
> Note that it replaces a local_irq_save(flags) by local_irq_disable().
> This is similar because the flags are never used. On ppc 8xx it is
> more efficient because it doesn't require reading MSR.

Can these cleanups go after my interrupt performance improvements?
I posted them for last series but were dropped due to crashes without
time to resubmit. I'm working on them again now.

Thanks,
Nick