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SubjectRe: [PATCH 5/8] arm64: irq: add a default handle_irq panic function
On 2021-02-22 09:59, Mark Rutland wrote:
> On Fri, Feb 19, 2021 at 11:39:01AM +0000, Mark Rutland wrote:
>> If we accidentally unmask IRQs before we've registered an IRQ
>> controller, handle_arch_irq will be NULL, and the IRQ exception
>> handler
>> will branch to a bogus address.
>>
>> To make this easier to debug, this patch initialises handle_arch_irq
>> to
>> a default handler which will panic(), making such problems easier to
>> debug. When we add support for FIQ handlers, we can follow the same
>> approach.
>
>> -void (*handle_arch_irq)(struct pt_regs *) __ro_after_init;
>> +void default_handle_irq(struct pt_regs *regs)
>> +{
>> + panic("IRQ taken without a registered IRQ controller\n");
>> +}
>
> The kbuild test robot pointed out that this should be static (likewise
> with default_handle_fiq in patch 8), since it's only used within this
> file, so I've updated that in my branch.
>
> Mark.
>
>> +
>> +void (*handle_arch_irq)(struct pt_regs *) __ro_after_init =
>> default_handle_irq;
>>
>> int __init set_handle_irq(void (*handle_irq)(struct pt_regs *))
>> {
>> - if (handle_arch_irq)
>> + if (handle_arch_irq != default_handle_irq)
>> return -EBUSY;
>>
>> handle_arch_irq = handle_irq;
>> @@ -87,7 +92,7 @@ void __init init_IRQ(void)
>> init_irq_stacks();
>> init_irq_scs();
>> irqchip_init();
>> - if (!handle_arch_irq)
>> + if (handle_arch_irq == default_handle_irq)
>> panic("No interrupt controller found.");

It also seems odd to have both default_handle_irq() that panics,
and init_IRQ that panics as well. Not a big deal, but maybe
we should just drop this altogether and get the firework on the
first interrupt.

Thanks,

M.
--
Jazz is not dead. It just smells funny...

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