Messages in this thread Patch in this message | | | From | Grzegorz Jaszczyk <> | Subject | [PATCH] arm64: kdump: fix interrupt handling done during machine_crash_shutdown | Date | Wed, 28 Feb 2018 18:01:00 +0100 |
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Hitherto during machine_kexec_mask_interrupts there was an attempt to remove active state using irq_set_irqchip_state() routine and only if it failed, the attempt to EOI the interrupt was made. Nevertheless relaying on return value from irq_set_irqchip_state inside machine_kexec_mask_interrupts is incorrect - it only returns the status of the routine but doesn't provide information if the interrupt was deactivated correctly or not. Therefore the irq_eoi wasn't call even if the interrupt remained active.
To determine the sate correctly the irq_get_irqchip_state() could be used but according to the ARM Generic Interrupt Controller Architecture Spec, non-secure reading from GICD_ISACTIVERn/GICD_ICACTIVERn can be not permitted (depending on NS_access setting of Non-secure Access Control Registers, a.k.a. GICD_NSACRn). What is more interesting GICD_NSACRn is optional Secure register.
Moreover de-activating the interrupt via GICD_ISACTIVERn register (regardless of the possibility of checking status or not) seems to not do the job, when the GIC Distributor is configured to forward the interrupts to the CPU interfaces.
Because of all above the attempt to deactivate interrupts via irq_set_irqchip_state() is removed in this patch. Instead the irq_eoi is called whenever the interrupt is in progress(irqd_irq_inprogress).
Before this patch the kdump triggered from interrupt context worked correctly by accident when the GIC was configured with GIC_CPU_CTRL_EOImodeNS == 1 (supports_deactivate == true). In mentioned mode GIC_CPU_EOI has priority drop functionality only and GIC_CPU_DEACTIVATE is used for interrupt deactivation. Also the gic_handle_irq behaviour is a bit different in mentioned mode and performs write to the GIC_CPU_EOI which causes the priority drop to the idle priority. So even if the irq_eoi wasn't called during machine_kexec_mask_interrupts, the interrupts of the crashdump kernel was handled due to interrupt preemption (since the priority of still active interrupt was dropped to idle priority).
Nevertheless when the kdump was triggered from interrupt context while the GIC was configured to work in GIC_CPU_CTRL_EOImodeNS == 0, the crashdump kernel hang in early stage due to lack of timer interrupt arrival.
After this fix the kdump behaves correctly when triggered from interrupt context independently of GIC_CPU_CTRL_EOImodeNS configuration.
Signed-off-by: Grzegorz Jaszczyk <jaz@semihalf.com> --- arch/arm64/kernel/machine_kexec.c | 10 +--------- 1 file changed, 1 insertion(+), 9 deletions(-)
diff --git a/arch/arm64/kernel/machine_kexec.c b/arch/arm64/kernel/machine_kexec.c index f76ea92..30ad183 100644 --- a/arch/arm64/kernel/machine_kexec.c +++ b/arch/arm64/kernel/machine_kexec.c @@ -220,20 +220,12 @@ static void machine_kexec_mask_interrupts(void) for_each_irq_desc(i, desc) { struct irq_chip *chip; - int ret; chip = irq_desc_get_chip(desc); if (!chip) continue; - /* - * First try to remove the active state. If this - * fails, try to EOI the interrupt. - */ - ret = irq_set_irqchip_state(i, IRQCHIP_STATE_ACTIVE, false); - - if (ret && irqd_irq_inprogress(&desc->irq_data) && - chip->irq_eoi) + if (irqd_irq_inprogress(&desc->irq_data) && chip->irq_eoi) chip->irq_eoi(&desc->irq_data); if (chip->irq_mask) -- 2.7.4
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