[PATCH 10/18] arm64: Introduce FIQ support
maz at kernel.org
Mon Feb 8 06:30:50 EST 2021
On Sun, 07 Feb 2021 08:47:23 +0000,
Hector Martin 'marcan' <marcan at marcan.st> wrote:
> On 07/02/2021 00.37, Marc Zyngier wrote:
> > See my digression in patch 8. I really wonder what the benefit is to
> > treat FIQ independently of IRQ, and we might as well generalise
> > this. We could always panic on getting a FIQ on platforms that don't
> > expect one.
> > It'd be good to rope in the other interested parties (Mark for the
> > early entry code, James for RAS and SError handling).
> CCing Mark and James: TL;DR what do you think about unconditionally
> keeping DAIF.I == DAIF.F, would this break other platforms with
> spurious FIQs or conversely mask FIQs when we don't want to in some
> cases? The FIQ vector would remain a panic except on platforms that
> require using it, via an alternatives patch.
> >> kernel_ventry 1, sync // Synchronous EL1h
> >> kernel_ventry 1, irq // IRQ EL1h
> >> - kernel_ventry 1, fiq_invalid // FIQ EL1h
> >> + // FIQ EL1h
> >> + kernel_ventry 1, fiq_invalid, 64, irq, ARM64_NEEDS_FIQ
> > It could be better to create a set of first class FIQ handlers rather
> > than this alternative target macro. I quickly hacked this instead,
> > which I find more readable.
> I think I ended up with the macro change to keep it 1:1 with IRQ, vs a
> separate branch... but I didn't think of the fallthrough-with-nop
> trick, neat. It is definitely is more readable. Are you OK with me
> pulling this patch in for v2, with your name on it?
Up to you, I don't mind either way. This is just code! :D
> > - kernel_ventry 0, fiq_invalid_compat, 32 // FIQ 32-bit EL0
> > + kernel_ventry 0, fiq, 32 // FIQ 32-bit EL0
> fiq_compat here, right?
Without deviation from the norm, progress is not possible.
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