From: Sumit Garg <sumit.g...@linaro.org>
Enable NMI backtrace support on arm64 using IPI turned as an NMI
leveraging pseudo NMIs support. It is now possible for users to get a
backtrace of a CPU stuck in hard-lockup using magic SYSRQ.
Signed-off-by: Sumit Garg <sumit.g...@linaro.org>
Tested-by: Masayoshi Mizuma <m.miz...@jp.fujitsu.com>
Tested-by: Chen-Yu Tsai <w...@csie.org>
Signed-off-by: Douglas Anderson <diand...@chromium.org>
---
Changes in v8:
- Removed "#ifdef CONFIG_SMP" since arm64 is always SMP
arch/arm64/include/asm/irq.h | 4 ++++
arch/arm64/kernel/ipi_nmi.c | 18 ++++++++++++++++--
2 files changed, 20 insertions(+), 2 deletions(-)
diff --git a/arch/arm64/include/asm/irq.h b/arch/arm64/include/asm/irq.h
index fac08e18bcd5..dc35b9d23a81 100644
--- a/arch/arm64/include/asm/irq.h
+++ b/arch/arm64/include/asm/irq.h
@@ -6,6 +6,10 @@
#include <asm-generic/irq.h>
+extern bool arch_trigger_cpumask_backtrace(const cpumask_t *mask,
+ bool exclude_self);
+#define arch_trigger_cpumask_backtrace arch_trigger_cpumask_backtrace
+
struct pt_regs;
int set_handle_irq(void (*handle_irq)(struct pt_regs *));
diff --git a/arch/arm64/kernel/ipi_nmi.c b/arch/arm64/kernel/ipi_nmi.c
index 712411eed949..c592e92b8cbf 100644
--- a/arch/arm64/kernel/ipi_nmi.c
+++ b/arch/arm64/kernel/ipi_nmi.c
@@ -8,6 +8,7 @@
#include <linux/interrupt.h>
#include <linux/irq.h>
+#include <linux/nmi.h>
#include <linux/smp.h>
#include <asm/nmi.h>
@@ -31,11 +32,24 @@ void arm64_send_nmi(cpumask_t *mask)
__ipi_send_mask(ipi_nmi_desc, mask);
}
+bool arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self)
+{
+ if (!ipi_nmi_desc)
+ return false;
+
+ nmi_trigger_cpumask_backtrace(mask, exclude_self, arm64_send_nmi);
+
+ return true;
+}
+
static irqreturn_t ipi_nmi_handler(int irq, void *data)
{
- /* nop, NMI handlers for special features can be added here. */
+ irqreturn_t ret = IRQ_NONE;
+
+ if (nmi_cpu_backtrace(get_irq_regs()))
+ ret = IRQ_HANDLED;
- return IRQ_NONE;
+ return ret;
}
void dynamic_ipi_setup(void)
--
2.40.0.634.g4ca3ef3211-goog
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