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authorThomas Gleixner <tglx@linutronix.de>2023-01-09 22:57:13 +0100
committerThomas Gleixner <tglx@linutronix.de>2023-01-16 17:24:56 +0100
commit5fa55950729d0762a787451dc52862c3f850f859 (patch)
tree9108450dd0aca71b10d66fc40e6aa32497ce9758
parent5dc4c995db9eb45f6373a956eb1f69460e69e6d4 (diff)
x86/i8259: Mark legacy PIC interrupts with IRQ_LEVEL
Baoquan reported that after triggering a crash the subsequent crash-kernel fails to boot about half of the time. It triggers a NULL pointer dereference in the periodic tick code. This happens because the legacy timer interrupt (IRQ0) is resent in software which happens in soft interrupt (tasklet) context. In this context get_irq_regs() returns NULL which leads to the NULL pointer dereference. The reason for the resend is a spurious APIC interrupt on the IRQ0 vector which is captured and leads to a resend when the legacy timer interrupt is enabled. This is wrong because the legacy PIC interrupts are level triggered and therefore should never be resent in software, but nothing ever sets the IRQ_LEVEL flag on those interrupts, so the core code does not know about their trigger type. Ensure that IRQ_LEVEL is set when the legacy PCI interrupts are set up. Fixes: a4633adcdbc1 ("[PATCH] genirq: add genirq sw IRQ-retrigger") Reported-by: Baoquan He <bhe@redhat.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Baoquan He <bhe@redhat.com> Link: https://lore.kernel.org/r/87mt6rjrra.ffs@tglx
-rw-r--r--arch/x86/kernel/i8259.c1
-rw-r--r--arch/x86/kernel/irqinit.c4
2 files changed, 4 insertions, 1 deletions
diff --git a/arch/x86/kernel/i8259.c b/arch/x86/kernel/i8259.c
index 3aa5304200c5..4d8aff05a509 100644
--- a/arch/x86/kernel/i8259.c
+++ b/arch/x86/kernel/i8259.c
@@ -114,6 +114,7 @@ static void make_8259A_irq(unsigned int irq)
disable_irq_nosync(irq);
io_apic_irqs &= ~(1<<irq);
irq_set_chip_and_handler(irq, &i8259A_chip, handle_level_irq);
+ irq_set_status_flags(irq, IRQ_LEVEL);
enable_irq(irq);
lapic_assign_legacy_vector(irq, true);
}
diff --git a/arch/x86/kernel/irqinit.c b/arch/x86/kernel/irqinit.c
index beb1bada1b0a..c683666876f1 100644
--- a/arch/x86/kernel/irqinit.c
+++ b/arch/x86/kernel/irqinit.c
@@ -65,8 +65,10 @@ void __init init_ISA_irqs(void)
legacy_pic->init(0);
- for (i = 0; i < nr_legacy_irqs(); i++)
+ for (i = 0; i < nr_legacy_irqs(); i++) {
irq_set_chip_and_handler(i, chip, handle_level_irq);
+ irq_set_status_flags(i, IRQ_LEVEL);
+ }
}
void __init init_IRQ(void)