From: Sumit Garg <sumit.g...@linaro.org>
Enable arch_trigger_cpumask_backtrace() support on arm64 using the new
debug IPI. With this arm64 can now get backtraces in cases where
callers of the trigger_xyz_backtrace() class of functions don't check
the return code and implement a fallback. One example is
`kernel.softlockup_all_cpu_backtrace`. This also allows us to
backtrace hard locked up CPUs in cases where the debug IPI is backed
by an NMI (or pseudo NMI).
Signed-off-by: Sumit Garg <sumit.g...@linaro.org>
Signed-off-by: Douglas Anderson <diand...@chromium.org>
---
Changes in v9:
- Added comments that we might not be using NMI always.
- Renamed "NMI IPI" to "debug IPI" since it might not be backed by NMI.
- arch_trigger_cpumask_backtrace() no longer returns bool
Changes in v8:
- Removed "#ifdef CONFIG_SMP" since arm64 is always SMP
arch/arm64/include/asm/irq.h | 3 +++
arch/arm64/kernel/ipi_debug.c | 25 +++++++++++++++++++++++--
2 files changed, 26 insertions(+), 2 deletions(-)
diff --git a/arch/arm64/include/asm/irq.h b/arch/arm64/include/asm/irq.h
index fac08e18bcd5..be2d103f316e 100644
--- a/arch/arm64/include/asm/irq.h
+++ b/arch/arm64/include/asm/irq.h
@@ -6,6 +6,9 @@
#include <asm-generic/irq.h>
+void 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_debug.c b/arch/arm64/kernel/ipi_debug.c
index b57833e31eaf..6984ed507e1f 100644
--- a/arch/arm64/kernel/ipi_debug.c
+++ b/arch/arm64/kernel/ipi_debug.c
@@ -8,6 +8,7 @@
#include <linux/interrupt.h>
#include <linux/irq.h>
+#include <linux/nmi.h>
#include <linux/smp.h>
#include "ipi_debug.h"
@@ -24,11 +25,31 @@ void arm64_debug_ipi(cpumask_t *mask)
__ipi_send_mask(ipi_debug_desc, mask);
}
+void arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self)
+{
+ /*
+ * NOTE: though nmi_trigger_cpumask_backtrace has "nmi_" in the name,
+ * nothing about it truly needs to be backed by an NMI, it's just that
+ * it's _allowed_ to be called from an NMI. If set_smp_debug_ipi()
+ * failed to get an NMI (or pseudo-NMI) this will just be backed by a
+ * regular IPI.
+ */
+ nmi_trigger_cpumask_backtrace(mask, exclude_self, arm64_debug_ipi);
+}
+
static irqreturn_t ipi_debug_handler(int irq, void *data)
{
- /* nop, NMI handlers for special features can be added here. */
+ irqreturn_t ret = IRQ_NONE;
+
+ /*
+ * NOTE: Just like in arch_trigger_cpumask_backtrace(), we're calling
+ * a function with "nmi_" in the name but it works fine even if we
+ * are using a regulaor IPI.
+ */
+ if (nmi_cpu_backtrace(get_irq_regs()))
+ ret = IRQ_HANDLED;
- return IRQ_NONE;
+ return ret;
}
void debug_ipi_setup(void)
--
2.41.0.rc2.161.g9c6817b8e7-goog
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