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From: Marc Zyngier <maz@kernel.org>
To: Mark Rutland <mark.rutland@arm.com>
Cc: catalin.marinas@arm.com, marcan@marcan.st,
	linux-kernel@vger.kernel.org, james.morse@arm.com,
	tglx@linutronix.de, will@kernel.org,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 5/8] arm64: irq: add a default handle_irq panic function
Date: Mon, 22 Feb 2021 10:48:11 +0000	[thread overview]
Message-ID: <1d2c27d72b9b2cbdb83d25165a20559a@kernel.org> (raw)
In-Reply-To: <20210222095913.GA70951@C02TD0UTHF1T.local>

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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WARNING: multiple messages have this Message-ID (diff)
From: Marc Zyngier <maz@kernel.org>
To: Mark Rutland <mark.rutland@arm.com>
Cc: linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, catalin.marinas@arm.com,
	james.morse@arm.com, marcan@marcan.st, tglx@linutronix.de,
	will@kernel.org
Subject: Re: [PATCH 5/8] arm64: irq: add a default handle_irq panic function
Date: Mon, 22 Feb 2021 10:48:11 +0000	[thread overview]
Message-ID: <1d2c27d72b9b2cbdb83d25165a20559a@kernel.org> (raw)
In-Reply-To: <20210222095913.GA70951@C02TD0UTHF1T.local>

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...

  reply	other threads:[~2021-02-22 10:49 UTC|newest]

Thread overview: 52+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-19 11:38 [PATCH 0/8] arm64: Support FIQ controller registration Mark Rutland
2021-02-19 11:38 ` Mark Rutland
2021-02-19 11:38 ` [PATCH 1/8] ARM: ep93xx: Select GENERIC_IRQ_MULTI_HANDLER directly Mark Rutland
2021-02-19 11:38   ` Mark Rutland
2021-02-19 11:38 ` [PATCH 2/8] irqchip: Do not blindly select CONFIG_GENERIC_IRQ_MULTI_HANDLER Mark Rutland
2021-02-19 11:38   ` Mark Rutland
2021-02-19 11:38 ` [PATCH 3/8] genirq: Allow architectures to override set_handle_irq() fallback Mark Rutland
2021-02-19 11:38   ` Mark Rutland
2021-02-19 11:39 ` [PATCH 4/8] arm64: don't use GENERIC_IRQ_MULTI_HANDLER Mark Rutland
2021-02-19 11:39   ` Mark Rutland
2021-02-19 11:39 ` [PATCH 5/8] arm64: irq: add a default handle_irq panic function Mark Rutland
2021-02-19 11:39   ` Mark Rutland
2021-02-22  9:59   ` Mark Rutland
2021-02-22  9:59     ` Mark Rutland
2021-02-22 10:48     ` Marc Zyngier [this message]
2021-02-22 10:48       ` Marc Zyngier
2021-02-22 11:25       ` Mark Rutland
2021-02-22 11:25         ` Mark Rutland
2021-02-22 11:43         ` Marc Zyngier
2021-02-22 11:43           ` Marc Zyngier
2021-02-22 12:06           ` Mark Rutland
2021-02-22 12:06             ` Mark Rutland
2021-02-22 12:23             ` Marc Zyngier
2021-02-22 12:23               ` Marc Zyngier
2021-02-19 11:39 ` [PATCH 6/8] arm64: entry: factor irq triage logic into macros Mark Rutland
2021-02-19 11:39   ` Mark Rutland
2021-02-19 11:39 ` [PATCH 7/8] arm64: Always keep DAIF.[IF] in sync Mark Rutland
2021-02-19 11:39   ` Mark Rutland
2021-02-19 17:25   ` [PATCH 7/8 v1.5] " Hector Martin
2021-02-19 17:25     ` Hector Martin
2021-02-19 18:26     ` Mark Rutland
2021-02-19 18:26       ` Mark Rutland
2021-02-22 17:39       ` Hector Martin
2021-02-22 17:39         ` Hector Martin
2021-02-22 18:43         ` Mark Rutland
2021-02-22 18:43           ` Mark Rutland
2021-02-19 11:39 ` [PATCH 8/8] arm64: irq: allow FIQs to be handled Mark Rutland
2021-02-19 11:39   ` Mark Rutland
2021-02-19 15:37   ` Joey Gouly
2021-02-19 15:37     ` Joey Gouly
2021-02-19 18:18     ` Mark Rutland
2021-02-19 18:18       ` Mark Rutland
2021-02-19 15:41 ` [PATCH 0/8] arm64: Support FIQ controller registration Hector Martin
2021-02-19 15:41   ` Hector Martin
2021-02-19 16:13   ` Mark Rutland
2021-02-19 16:13     ` Mark Rutland
2021-02-19 18:10 ` Marc Zyngier
2021-02-19 18:10   ` Marc Zyngier
2021-02-24 14:06   ` Mark Rutland
2021-02-24 14:06     ` Mark Rutland
2021-02-24 14:32     ` Marc Zyngier
2021-02-24 14:32       ` Marc Zyngier

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