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authorDaniel Thompson <daniel.thompson@linaro.org>2015-09-11 13:41:24 +0100
committerDaniel Thompson <daniel.thompson@linaro.org>2017-03-30 17:55:53 +0100
commitafd1ebd73afe91475d4e0914ae55711fbfa29e7a (patch)
treefabf6a28674e9d10b0ec222d0492b719185bbc6c
parent5288e43cb853300f74f5005be2347eb021ff0359 (diff)
downloadlinux-afd1ebd73afe91475d4e0914ae55711fbfa29e7a.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.h4
-rw-r--r--arch/arm64/kernel/smp.c23
-rw-r--r--lib/nmi_backtrace.c8
4 files changed, 33 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..7fe8538e1f80 100644
--- a/arch/arm64/include/asm/irq.h
+++ b/arch/arm64/include/asm/irq.h
@@ -56,5 +56,9 @@ static inline bool on_irq_stack(unsigned long sp, int cpu)
return (low <= sp && sp <= high);
}
+extern void arch_trigger_cpumask_backtrace(const cpumask_t *mask,
+ bool exclude_self);
+#define arch_trigger_cpumask_backtrace arch_trigger_cpumask_backtrace
+
#endif /* !__ASSEMBLER__ */
#endif
diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index 01e84055c1d4..b1b4df396965 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -39,6 +39,7 @@
#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>
@@ -78,7 +79,8 @@ enum ipi_msg_type {
IPI_CPU_STOP,
IPI_TIMER,
IPI_IRQ_WORK,
- IPI_WAKEUP
+ IPI_WAKEUP,
+ IPI_CPU_BACKTRACE,
};
#ifdef CONFIG_ARM64_VHE
@@ -772,6 +774,7 @@ 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)
@@ -897,6 +900,14 @@ 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;
@@ -970,3 +981,13 @@ bool cpus_are_stuck_in_kernel(void)
return !!cpus_stuck_in_kernel || smp_spin_tables;
}
+
+static void raise_nmi(cpumask_t *mask)
+{
+ smp_cross_call(mask, IPI_CPU_BACKTRACE);
+}
+
+void arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self)
+{
+ nmi_trigger_cpumask_backtrace(mask, exclude_self, raise_nmi);
+}
diff --git a/lib/nmi_backtrace.c b/lib/nmi_backtrace.c
index 4e8a30d1c22f..f0336e463c25 100644
--- a/lib/nmi_backtrace.c
+++ b/lib/nmi_backtrace.c
@@ -94,10 +94,14 @@ bool nmi_cpu_backtrace(struct pt_regs *regs)
cpu, instruction_pointer(regs));
} else {
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;