v4.19.13 snapshot.
diff --git a/arch/mips/kernel/smp-up.c b/arch/mips/kernel/smp-up.c
new file mode 100644
index 0000000..525d319
--- /dev/null
+++ b/arch/mips/kernel/smp-up.c
@@ -0,0 +1,79 @@
+/*
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License. See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 2006, 07 by Ralf Baechle (ralf@linux-mips.org)
+ *
+ * Symmetric Uniprocessor (TM) Support
+ */
+#include <linux/kernel.h>
+#include <linux/sched.h>
+
+/*
+ * Send inter-processor interrupt
+ */
+static void up_send_ipi_single(int cpu, unsigned int action)
+{
+ panic(KERN_ERR "%s called", __func__);
+}
+
+static inline void up_send_ipi_mask(const struct cpumask *mask,
+ unsigned int action)
+{
+ panic(KERN_ERR "%s called", __func__);
+}
+
+/*
+ * After we've done initial boot, this function is called to allow the
+ * board code to clean up state, if needed
+ */
+static void up_init_secondary(void)
+{
+}
+
+static void up_smp_finish(void)
+{
+}
+
+/*
+ * Firmware CPU startup hook
+ */
+static int up_boot_secondary(int cpu, struct task_struct *idle)
+{
+ return 0;
+}
+
+static void __init up_smp_setup(void)
+{
+}
+
+static void __init up_prepare_cpus(unsigned int max_cpus)
+{
+}
+
+#ifdef CONFIG_HOTPLUG_CPU
+static int up_cpu_disable(void)
+{
+ return -ENOSYS;
+}
+
+static void up_cpu_die(unsigned int cpu)
+{
+ BUG();
+}
+#endif
+
+const struct plat_smp_ops up_smp_ops = {
+ .send_ipi_single = up_send_ipi_single,
+ .send_ipi_mask = up_send_ipi_mask,
+ .init_secondary = up_init_secondary,
+ .smp_finish = up_smp_finish,
+ .boot_secondary = up_boot_secondary,
+ .smp_setup = up_smp_setup,
+ .prepare_cpus = up_prepare_cpus,
+#ifdef CONFIG_HOTPLUG_CPU
+ .cpu_disable = up_cpu_disable,
+ .cpu_die = up_cpu_die,
+#endif
+};