v4.19.13 snapshot.
diff --git a/arch/um/kernel/sysrq.c b/arch/um/kernel/sysrq.c
new file mode 100644
index 0000000..6b995e8
--- /dev/null
+++ b/arch/um/kernel/sysrq.c
@@ -0,0 +1,60 @@
+/*
+ * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
+ * Copyright (C) 2013 Richard Weinberger <richrd@nod.at>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/kallsyms.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/sched/debug.h>
+#include <linux/sched/task_stack.h>
+
+#include <asm/sysrq.h>
+#include <asm/stacktrace.h>
+#include <os.h>
+
+static void _print_addr(void *data, unsigned long address, int reliable)
+{
+ pr_info(" [<%08lx>] %s%pF\n", address, reliable ? "" : "? ",
+ (void *)address);
+}
+
+static const struct stacktrace_ops stackops = {
+ .address = _print_addr
+};
+
+void show_stack(struct task_struct *task, unsigned long *stack)
+{
+ unsigned long *sp = stack;
+ struct pt_regs *segv_regs = current->thread.segv_regs;
+ int i;
+
+ if (!segv_regs && os_is_signal_stack()) {
+ pr_err("Received SIGSEGV in SIGSEGV handler,"
+ " aborting stack trace!\n");
+ return;
+ }
+
+ if (!stack)
+ sp = get_stack_pointer(task, segv_regs);
+
+ pr_info("Stack:\n");
+ stack = sp;
+ for (i = 0; i < 3 * STACKSLOTS_PER_LINE; i++) {
+ if (kstack_end(stack))
+ break;
+ if (i && ((i % STACKSLOTS_PER_LINE) == 0))
+ pr_cont("\n");
+ pr_cont(" %08lx", *stack++);
+ }
+ pr_cont("\n");
+
+ pr_info("Call Trace:\n");
+ dump_trace(current, &stackops, NULL);
+ pr_info("\n");
+}