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authorDaniel Thompson <daniel.thompson@linaro.org>2015-09-11 13:41:24 +0100
committerDaniel Thompson <daniel.thompson@linaro.org>2016-06-17 17:02:30 +0100
commitc0c52bdbc5cb4419c7b0646e74b8789b9f8b0cc6 (patch)
tree62456f9d0180b1269b1301693f2167f77bffaf6e
parent603610b9b06a82f0cd2cabec2e4b6a68f9e78b91 (diff)
downloadlinux-c0c52bdbc5cb4419c7b0646e74b8789b9f8b0cc6.tar.gz
arm64: Add support for on-demand backtrace of other CPUs
Currently arm64 has no implementation of arch_trigger_all_cpu_backtace. The patch provides one using library code recently added by Russell King for for the majority of the implementation. Currently this is realized using regular irqs but could, in the future, be implemented using NMI-like mechanisms. Note: There is a small (and nasty) change to the generic code to ensure good stack traces. The generic code currently assumes that show_regs() will include a stack trace but arch/arm64 does not do this so we must add extra code here. Ideas on a better approach here would be very welcome (is there any appetite to change arm64 show_regs() or should we just tease out the dump code into a callback?). Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org> Cc: Russell King <rmk+kernel@arm.linux.org.uk>
-rw-r--r--arch/arm64/include/asm/hardirq.h2
-rw-r--r--arch/arm64/include/asm/irq.h3
-rw-r--r--arch/arm64/kernel/smp.c30
-rw-r--r--lib/nmi_backtrace.c9
4 files changed, 40 insertions, 4 deletions
diff --git a/arch/arm64/include/asm/hardirq.h b/arch/arm64/include/asm/hardirq.h
index 8740297dac77..1473fc2f7ab7 100644
--- a/arch/arm64/include/asm/hardirq.h
+++ b/arch/arm64/include/asm/hardirq.h
@@ -20,7 +20,7 @@
#include <linux/threads.h>
#include <asm/irq.h>
-#define NR_IPI 6
+#define NR_IPI 7
typedef struct {
unsigned int __softirq_pending;
diff --git a/arch/arm64/include/asm/irq.h b/arch/arm64/include/asm/irq.h
index b77197d941fc..67dc130ae517 100644
--- a/arch/arm64/include/asm/irq.h
+++ b/arch/arm64/include/asm/irq.h
@@ -56,5 +56,8 @@ static inline bool on_irq_stack(unsigned long sp, int cpu)
return (low <= sp && sp <= high);
}
+extern void arch_trigger_all_cpu_backtrace(bool);
+#define arch_trigger_all_cpu_backtrace(x) arch_trigger_all_cpu_backtrace(x)
+
#endif /* !__ASSEMBLER__ */
#endif
diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index 678e0842cb3b..c09b4e8507ab 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -37,6 +37,7 @@
#include <linux/completion.h>
#include <linux/of.h>
#include <linux/irq_work.h>
+#include <linux/nmi.h>
#include <asm/alternative.h>
#include <asm/atomic.h>
@@ -73,7 +74,8 @@ enum ipi_msg_type {
IPI_CPU_STOP,
IPI_TIMER,
IPI_IRQ_WORK,
- IPI_WAKEUP
+ IPI_CPU_BACKTRACE,
+ IPI_WAKEUP,
};
#ifdef CONFIG_ARM64_VHE
@@ -728,6 +730,7 @@ static const char *ipi_types[NR_IPI] __tracepoint_string = {
S(IPI_CPU_STOP, "CPU stop interrupts"),
S(IPI_TIMER, "Timer broadcast interrupts"),
S(IPI_IRQ_WORK, "IRQ work interrupts"),
+ S(IPI_CPU_BACKTRACE, "backtrace interrupts"),
S(IPI_WAKEUP, "CPU wake-up interrupts"),
};
@@ -846,6 +849,14 @@ void handle_IPI(int ipinr, struct pt_regs *regs)
break;
#endif
+ case IPI_CPU_BACKTRACE:
+ printk_nmi_enter();
+ irq_enter();
+ nmi_cpu_backtrace(regs);
+ irq_exit();
+ printk_nmi_exit();
+ break;
+
#ifdef CONFIG_ARM64_ACPI_PARKING_PROTOCOL
case IPI_WAKEUP:
WARN_ONCE(!acpi_parking_protocol_valid(cpu),
@@ -909,3 +920,20 @@ int setup_profiling_timer(unsigned int multiplier)
{
return -EINVAL;
}
+
+static void raise_nmi(cpumask_t *mask)
+{
+ /*
+ * Generate the backtrace directly if we are running in a
+ * calling context that is not preemptible by the backtrace IPI.
+ */
+ if (cpumask_test_cpu(smp_processor_id(), mask) && irqs_disabled())
+ nmi_cpu_backtrace(NULL);
+
+ smp_cross_call(mask, IPI_CPU_BACKTRACE);
+}
+
+void arch_trigger_all_cpu_backtrace(bool include_self)
+{
+ nmi_trigger_all_cpu_backtrace(include_self, raise_nmi);
+}
diff --git a/lib/nmi_backtrace.c b/lib/nmi_backtrace.c
index 26caf51cc238..3dada8487477 100644
--- a/lib/nmi_backtrace.c
+++ b/lib/nmi_backtrace.c
@@ -78,10 +78,15 @@ bool nmi_cpu_backtrace(struct pt_regs *regs)
if (cpumask_test_cpu(cpu, to_cpumask(backtrace_mask))) {
pr_warn("NMI backtrace for cpu %d\n", cpu);
- if (regs)
+ if (regs) {
show_regs(regs);
- else
+#ifdef CONFIG_ARM64
+ show_stack(NULL, NULL);
+#endif
+ } else {
dump_stack();
+ }
+
cpumask_clear_cpu(cpu, to_cpumask(backtrace_mask));
return true;
}