[PATCH 5/8] arm64: irq: add a default handle_irq panic function

Mark Rutland mark.rutland at arm.com
Fri Feb 19 06:39:01 EST 2021

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

Signed-off-by: Mark Rutland <mark.rutland at arm.com>
Cc: Catalin Marinas <catalin.marinas at arm.com>
Cc: Hector Martin <marcan at marcan.st>
Cc: James Morse <james.morse at arm.com>
Cc: Marc Zyngier <maz at kernel.org>
Cc: Thomas Gleixner <tglx at linutronix.de>
Cc: Will Deacon <will at kernel.org>
 arch/arm64/kernel/irq.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/kernel/irq.c b/arch/arm64/kernel/irq.c
index ad63bd50fa7b..00bcf37aa0ea 100644
--- a/arch/arm64/kernel/irq.c
+++ b/arch/arm64/kernel/irq.c
@@ -71,11 +71,16 @@ static void init_irq_stacks(void)
-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");
+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)
-	if (!handle_arch_irq)
+	if (handle_arch_irq == default_handle_irq)
 		panic("No interrupt controller found.");
 	if (system_uses_irq_prio_masking()) {

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