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From: Sumit Garg <sumit.garg@linaro.org>
To: maz@kernel.org, catalin.marinas@arm.com, will@kernel.org
Cc: linux-arm-kernel@lists.infradead.org, tglx@linutronix.de,
	jason@lakedaemon.net, mark.rutland@arm.com,
	julien.thierry.kdev@gmail.com, dianders@chromium.org,
	daniel.thompson@linaro.org, jason.wessel@windriver.com,
	msys.mizuma@gmail.com, ito-yuichi@fujitsu.com,
	kgdb-bugreport@lists.sourceforge.net,
	linux-kernel@vger.kernel.org, Sumit Garg <sumit.garg@linaro.org>
Subject: [PATCH v5 5/5] arm64: ipi_nmi: Add support for NMI backtrace
Date: Wed, 14 Oct 2020 16:42:11 +0530	[thread overview]
Message-ID: <1602673931-28782-6-git-send-email-sumit.garg@linaro.org> (raw)
In-Reply-To: <1602673931-28782-1-git-send-email-sumit.garg@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.garg@linaro.org>
---
 arch/arm64/include/asm/irq.h |  6 ++++++
 arch/arm64/kernel/ipi_nmi.c  | 12 +++++++++++-
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/include/asm/irq.h b/arch/arm64/include/asm/irq.h
index b2b0c64..e840bf1 100644
--- a/arch/arm64/include/asm/irq.h
+++ b/arch/arm64/include/asm/irq.h
@@ -6,6 +6,12 @@
 
 #include <asm-generic/irq.h>
 
+#ifdef CONFIG_SMP
+extern void arch_trigger_cpumask_backtrace(const cpumask_t *mask,
+					   bool exclude_self);
+#define arch_trigger_cpumask_backtrace arch_trigger_cpumask_backtrace
+#endif
+
 struct pt_regs;
 
 static inline int nr_legacy_irqs(void)
diff --git a/arch/arm64/kernel/ipi_nmi.c b/arch/arm64/kernel/ipi_nmi.c
index e0a9e03..e1dc19d 100644
--- a/arch/arm64/kernel/ipi_nmi.c
+++ b/arch/arm64/kernel/ipi_nmi.c
@@ -9,6 +9,7 @@
 #include <linux/interrupt.h>
 #include <linux/irq.h>
 #include <linux/kgdb.h>
+#include <linux/nmi.h>
 #include <linux/smp.h>
 
 #include <asm/nmi.h>
@@ -25,12 +26,21 @@ void arch_send_call_nmi_func_ipi_mask(cpumask_t *mask)
 	__ipi_send_mask(ipi_desc, mask);
 }
 
+void arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self)
+{
+	nmi_trigger_cpumask_backtrace(mask, exclude_self,
+				      arch_send_call_nmi_func_ipi_mask);
+}
+
 static irqreturn_t ipi_nmi_handler(int irq, void *data)
 {
 	unsigned int cpu = smp_processor_id();
 
-	ipi_kgdb_nmicallback(cpu, get_irq_regs());
+	if (nmi_cpu_backtrace(get_irq_regs()))
+		goto out;
 
+	ipi_kgdb_nmicallback(cpu, get_irq_regs());
+out:
 	return IRQ_HANDLED;
 }
 
-- 
2.7.4


  parent reply	other threads:[~2020-10-14 11:13 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-14 11:12 [PATCH v5 0/5] arm64: Add framework to turn an IPI as NMI Sumit Garg
2020-10-14 11:12 ` [PATCH v5 1/5] arm64: Add framework to turn " Sumit Garg
2020-10-15  1:15   ` Masayoshi Mizuma
2020-10-19 11:37   ` Marc Zyngier
2020-10-20  6:43     ` Sumit Garg
2020-10-20 10:08       ` Marc Zyngier
2020-10-20 11:22         ` Sumit Garg
2020-10-20 12:25           ` Daniel Thompson
2020-10-20 12:32             ` Marc Zyngier
2020-10-21  5:22               ` Sumit Garg
2020-10-21 10:27           ` Marc Zyngier
2020-10-22 11:52             ` Sumit Garg
2020-10-19 11:56   ` Marc Zyngier
2020-10-20  7:07     ` Sumit Garg
2020-10-14 11:12 ` [PATCH v5 2/5] irqchip/gic-v3: Enable support for SGIs to act as NMIs Sumit Garg
2020-10-15  1:16   ` Masayoshi Mizuma
2020-10-19 12:07   ` Marc Zyngier
2020-10-20  7:24     ` Sumit Garg
2020-10-14 11:12 ` [PATCH v5 3/5] arm64: smp: Allocate and setup IPI as NMI Sumit Garg
2020-10-15  1:16   ` Masayoshi Mizuma
2020-10-19 11:59   ` Marc Zyngier
2020-10-20  7:16     ` Sumit Garg
2020-10-14 11:12 ` [PATCH v5 4/5] arm64: kgdb: Round up cpus using " Sumit Garg
2020-10-19 12:15   ` Marc Zyngier
2020-10-20  8:51     ` Sumit Garg
2020-10-14 11:12 ` Sumit Garg [this message]
2020-10-15  1:17   ` [PATCH v5 5/5] arm64: ipi_nmi: Add support for NMI backtrace Masayoshi Mizuma
2020-10-19 12:20   ` Marc Zyngier
2020-10-20  9:13     ` Sumit Garg
2020-10-21 10:32       ` Marc Zyngier
2020-10-21 11:28         ` Sumit Garg

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