@@ -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;
@@ -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
@@ -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_WAKEUP,
+ IPI_CPU_BACKTRACE,
};
#ifdef CONFIG_ARM64_VHE
@@ -737,6 +739,7 @@ static const char *ipi_types[NR_IPI] __tracepoint_string = {
S(IPI_TIMER, "Timer broadcast interrupts"),
S(IPI_IRQ_WORK, "IRQ work interrupts"),
S(IPI_WAKEUP, "CPU wake-up interrupts"),
+ S(IPI_CPU_BACKTRACE, "backtrace interrupts"),
};
static void smp_cross_call(const struct cpumask *target, unsigned int ipinr)
@@ -862,6 +865,14 @@ 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;
+
default:
pr_crit("CPU%u: Unknown IPI message 0x%x\n", cpu, ipinr);
break;
@@ -935,3 +946,20 @@ bool cpus_are_stuck_in_kernel(void)
return !!cpus_stuck_in_kernel || smp_spin_tables;
}
+
+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);
+}
@@ -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;
}
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> --- arch/arm64/include/asm/hardirq.h | 2 +- arch/arm64/include/asm/irq.h | 3 +++ arch/arm64/kernel/smp.c | 30 +++++++++++++++++++++++++++++- lib/nmi_backtrace.c | 9 +++++++-- 4 files changed, 40 insertions(+), 4 deletions(-) -- 2.7.4