Re: [PATCH v3 05/19] powerpc: interrupt handler wrapper functions

[Nicholas Piggin <npiggin@gmail.com>]

Excerpts from Aneesh Kumar K.V's message of November 30, 2020 5:37 pm:
> Nicholas Piggin <npiggin@gmail.com> writes:
> 
> .....
>  +#endif
>> +DECLARE_INTERRUPT_HANDLER(emulation_assist_interrupt);
>> +DECLARE_INTERRUPT_HANDLER_RAW(do_slb_fault);
> 
> Can we add comments here explaining why some of these handlers need to remain RAW()?

I possibly could. My patch doesn't change the reason, of course, they 
already have these issues.

It wants to avoid reconciling interrupts and probably context tracking 
because you can take SLB faults within those subsystems, which are not 
expecting re-entrant calls into them. It's okay to avoid these things 
because the interrupts don't enable interrupts, go to process context, 
add any timers, etc.

Now that I look at it, possibly the primary do_hash_fault handler needs 
to be RAW as well for the same reason.

 
>> +DECLARE_INTERRUPT_HANDLER(do_bad_slb_fault);
>> +DECLARE_INTERRUPT_HANDLER_RET(do_hash_fault);
>> +DECLARE_INTERRUPT_HANDLER_RET(do_page_fault);
>> +DECLARE_INTERRUPT_HANDLER(do_bad_page_fault);
>> +
>> +DECLARE_INTERRUPT_HANDLER_ASYNC(timer_interrupt);
>> +DECLARE_INTERRUPT_HANDLER_NMI(performance_monitor_exception_nmi);
>> +DECLARE_INTERRUPT_HANDLER_ASYNC(performance_monitor_exception_async);
>> +DECLARE_INTERRUPT_HANDLER_RAW(performance_monitor_exception);
> 
> Same for this.

That's just because nmi vs async is decided at runtime for PMIs. I can 
add a comment, although it's more obvious when looking at the body.

Thanks,
Nick