Hi Hector, On Mon, Feb 15, 2021 at 09:16:57PM +0900, Hector Martin wrote: > From: Marc Zyngier <maz@xxxxxxxxxx> > > By default, FIQ exceptions trigger a panic. On platforms that need to > deliver interrupts via FIQ, this gets redirected via an alternative to > instead handle FIQ the same way as IRQ. It is up to the irqchip handler > to discriminate between the two. > > Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx> > Signed-off-by: Hector Martin <marcan@xxxxxxxxx> Since the use of FIQ is a platform integration detail rather than a CPU implementation detail (and e.g. can differ across bare-metal and VM), I'd prefer to always have separate registered handlers for IRQ/FIQ (also avoiding the need for patching). That way we can explicitly opt-in to FIQ when required, and avoid edge-cases where an unexpected FIQ could livelock an unaware IRQ handler. Marc and I had a quick play with that, and I have a series of patches I've pushed to: https://git.kernel.org/pub/scm/linux/kernel/git/mark/linux.git/log/?h=arm64/fiq git://git.kernel.org/pub/scm/linux/kernel/git/mark/linux.git arm64/fiq ... which I'll post out shortly. Thanks, Mark. > --- > arch/arm64/kernel/entry.S | 21 ++++++++++++++++++--- > 1 file changed, 18 insertions(+), 3 deletions(-) > > diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S > index ba5f9aa379ce..bcfd1ac72636 100644 > --- a/arch/arm64/kernel/entry.S > +++ b/arch/arm64/kernel/entry.S > @@ -547,18 +547,18 @@ 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 > @@ -658,6 +658,10 @@ SYM_CODE_START_LOCAL_NOALIGN(el1_sync) > SYM_CODE_END(el1_sync) > > .align 6 > +SYM_CODE_START_LOCAL_NOALIGN(el1_fiq) > +alternative_if_not ARM64_NEEDS_FIQ > + b el1_fiq_invalid > +alternative_else_nop_endif > SYM_CODE_START_LOCAL_NOALIGN(el1_irq) > kernel_entry 1 > gic_prio_irq_setup pmr=x20, tmp=x1 > @@ -688,6 +692,7 @@ alternative_else_nop_endif > > kernel_exit 1 > SYM_CODE_END(el1_irq) > +SYM_CODE_END(el1_fiq) > > /* > * EL0 mode handlers. > @@ -710,10 +715,15 @@ SYM_CODE_START_LOCAL_NOALIGN(el0_sync_compat) > SYM_CODE_END(el0_sync_compat) > > .align 6 > +SYM_CODE_START_LOCAL_NOALIGN(el0_fiq_compat) > +alternative_if_not ARM64_NEEDS_FIQ > + b el0_fiq_invalid_compat > +alternative_else_nop_endif > SYM_CODE_START_LOCAL_NOALIGN(el0_irq_compat) > kernel_entry 0, 32 > b el0_irq_naked > SYM_CODE_END(el0_irq_compat) > +SYM_CODE_END(el0_fiq_compat) > > SYM_CODE_START_LOCAL_NOALIGN(el0_error_compat) > kernel_entry 0, 32 > @@ -722,6 +732,10 @@ SYM_CODE_END(el0_error_compat) > #endif > > .align 6 > +SYM_CODE_START_LOCAL_NOALIGN(el0_fiq) > +alternative_if_not ARM64_NEEDS_FIQ > + b el0_fiq_invalid > +alternative_else_nop_endif > SYM_CODE_START_LOCAL_NOALIGN(el0_irq) > kernel_entry 0 > el0_irq_naked: > @@ -736,6 +750,7 @@ el0_irq_naked: > > b ret_to_user > SYM_CODE_END(el0_irq) > +SYM_CODE_END(el0_fiq) > > SYM_CODE_START_LOCAL(el1_error) > kernel_entry 1 > -- > 2.30.0 >
