Re: [PATCH 8/8] arm64: irq: allow FIQs to be handled

From: Mark Rutland
Date: Fri Feb 19 2021 - 13:20:04 EST


On Fri, Feb 19, 2021 at 03:37:25PM +0000, Joey Gouly wrote:
> Hi Mark,
>
> On Fri, Feb 19, 2021 at 11:39:04AM +0000, Mark Rutland wrote:
> > On contemporary platforms we don't use FIQ, and treat any stray FIQ as a
> > fatal event. However, some platforms have an interrupt controller wired
> > to FIQ, and need to handle FIQ as part of regular operation.
> >
>
> [...]
>
> > diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
> > index 0474cca9f1a9..a8290bd87a49 100644
> > --- a/arch/arm64/kernel/entry.S
> > +++ b/arch/arm64/kernel/entry.S
> > @@ -586,23 +586,23 @@ SYM_CODE_START(vectors)
> >
> > kernel_ventry 1, sync // Synchronous EL1h
> > kernel_ventry 1, irq // IRQ EL1h
> > - kernel_ventry 1, fiq_invalid // FIQ EL1h
> > + kernel_ventry 1, fiq // FIQ EL1h
> > kernel_ventry 1, error // Error EL1h
> >
> > kernel_ventry 0, sync // Synchronous 64-bit EL0
> > kernel_ventry 0, irq // IRQ 64-bit EL0
> > - kernel_ventry 0, fiq_invalid // FIQ 64-bit EL0
> > + kernel_ventry 0, fiq // FIQ 64-bit EL0
> > kernel_ventry 0, error // Error 64-bit EL0
> >
> > #ifdef CONFIG_COMPAT
> > kernel_ventry 0, sync_compat, 32 // Synchronous 32-bit EL0
> > kernel_ventry 0, irq_compat, 32 // IRQ 32-bit EL0
> > - kernel_ventry 0, fiq_invalid_compat, 32 // FIQ 32-bit EL0
> > + kernel_ventry 0, fiq_compat, 32 // FIQ 32-bit EL0
> > kernel_ventry 0, error_compat, 32 // Error 32-bit EL0
> > #else
> > kernel_ventry 0, sync_invalid, 32 // Synchronous 32-bit EL0
> > kernel_ventry 0, irq_invalid, 32 // IRQ 32-bit EL0
> > - kernel_ventry 0, fiq_invalid, 32 // FIQ 32-bit EL0
> > + kernel_ventry 0, fiq, 32 // FIQ 32-bit EL0
> > kernel_ventry 0, error_invalid, 32 // Error 32-bit EL0
> > #endif
> > SYM_CODE_END(vectors)
>
> I believe you can now remove functions `el0_fiq_invalid` and `el0_fiq_invalid_compat`.
> `el1_fiq_invalid` is still used by Synchronous EL1t, so can't be removed.

Good spot; el0_fiq_invalid_compat can go. For the !CONFIG_COMPAT it was
wrong to move away from fiq_invalid as that vector should never
legimitately fire, so I'll revert back to fiq_invalid for that case and
match the rest of the !CONFIG_COMPAT AArch32 EL0 handlers.

Thanks,
Mark.