v4.19.13 snapshot.
diff --git a/arch/mips/kernel/crash.c b/arch/mips/kernel/crash.c
new file mode 100644
index 0000000..4c07a43
--- /dev/null
+++ b/arch/mips/kernel/crash.c
@@ -0,0 +1,101 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/kernel.h>
+#include <linux/smp.h>
+#include <linux/reboot.h>
+#include <linux/kexec.h>
+#include <linux/bootmem.h>
+#include <linux/crash_dump.h>
+#include <linux/delay.h>
+#include <linux/irq.h>
+#include <linux/types.h>
+#include <linux/sched.h>
+#include <linux/sched/task_stack.h>
+
+/* This keeps a track of which one is crashing cpu. */
+static int crashing_cpu = -1;
+static cpumask_t cpus_in_crash = CPU_MASK_NONE;
+
+#ifdef CONFIG_SMP
+static void crash_shutdown_secondary(void *passed_regs)
+{
+ struct pt_regs *regs = passed_regs;
+ int cpu = smp_processor_id();
+
+ /*
+ * If we are passed registers, use those. Otherwise get the
+ * regs from the last interrupt, which should be correct, as
+ * we are in an interrupt. But if the regs are not there,
+ * pull them from the top of the stack. They are probably
+ * wrong, but we need something to keep from crashing again.
+ */
+ if (!regs)
+ regs = get_irq_regs();
+ if (!regs)
+ regs = task_pt_regs(current);
+
+ if (!cpu_online(cpu))
+ return;
+
+ /* We won't be sent IPIs any more. */
+ set_cpu_online(cpu, false);
+
+ local_irq_disable();
+ if (!cpumask_test_cpu(cpu, &cpus_in_crash))
+ crash_save_cpu(regs, cpu);
+ cpumask_set_cpu(cpu, &cpus_in_crash);
+
+ while (!atomic_read(&kexec_ready_to_reboot))
+ cpu_relax();
+ relocated_kexec_smp_wait(NULL);
+ /* NOTREACHED */
+}
+
+static void crash_kexec_prepare_cpus(void)
+{
+ static int cpus_stopped;
+ unsigned int msecs;
+ unsigned int ncpus;
+
+ if (cpus_stopped)
+ return;
+
+ ncpus = num_online_cpus() - 1;/* Excluding the panic cpu */
+
+ smp_call_function(crash_shutdown_secondary, NULL, 0);
+ smp_wmb();
+
+ /*
+ * The crash CPU sends an IPI and wait for other CPUs to
+ * respond. Delay of at least 10 seconds.
+ */
+ pr_emerg("Sending IPI to other cpus...\n");
+ msecs = 10000;
+ while ((cpumask_weight(&cpus_in_crash) < ncpus) && (--msecs > 0)) {
+ cpu_relax();
+ mdelay(1);
+ }
+
+ cpus_stopped = 1;
+}
+
+/* Override the weak function in kernel/panic.c */
+void crash_smp_send_stop(void)
+{
+ if (_crash_smp_send_stop)
+ _crash_smp_send_stop();
+
+ crash_kexec_prepare_cpus();
+}
+
+#else /* !defined(CONFIG_SMP) */
+static void crash_kexec_prepare_cpus(void) {}
+#endif /* !defined(CONFIG_SMP) */
+
+void default_machine_crash_shutdown(struct pt_regs *regs)
+{
+ local_irq_disable();
+ crashing_cpu = smp_processor_id();
+ crash_save_cpu(regs, crashing_cpu);
+ crash_kexec_prepare_cpus();
+ cpumask_set_cpu(crashing_cpu, &cpus_in_crash);
+}