v4.19.13 snapshot.
diff --git a/arch/mips/include/asm/stacktrace.h b/arch/mips/include/asm/stacktrace.h
new file mode 100644
index 0000000..8ad25c2
--- /dev/null
+++ b/arch/mips/include/asm/stacktrace.h
@@ -0,0 +1,89 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_STACKTRACE_H
+#define _ASM_STACKTRACE_H
+
+#include <asm/ptrace.h>
+#include <asm/asm.h>
+#include <linux/stringify.h>
+
+#ifdef CONFIG_KALLSYMS
+extern int raw_show_trace;
+extern unsigned long unwind_stack(struct task_struct *task, unsigned long *sp,
+ unsigned long pc, unsigned long *ra);
+extern unsigned long unwind_stack_by_address(unsigned long stack_page,
+ unsigned long *sp,
+ unsigned long pc,
+ unsigned long *ra);
+#else
+#define raw_show_trace 1
+static inline unsigned long unwind_stack(struct task_struct *task,
+ unsigned long *sp, unsigned long pc, unsigned long *ra)
+{
+ return 0;
+}
+#endif
+
+#define STR_PTR_LA __stringify(PTR_LA)
+#define STR_LONG_S __stringify(LONG_S)
+#define STR_LONG_L __stringify(LONG_L)
+#define STR_LONGSIZE __stringify(LONGSIZE)
+
+#define STORE_ONE_REG(r) \
+ STR_LONG_S " $" __stringify(r)",("STR_LONGSIZE"*"__stringify(r)")(%1)\n\t"
+
+static __always_inline void prepare_frametrace(struct pt_regs *regs)
+{
+#ifndef CONFIG_KALLSYMS
+ /*
+ * Remove any garbage that may be in regs (specially func
+ * addresses) to avoid show_raw_backtrace() to report them
+ */
+ memset(regs, 0, sizeof(*regs));
+#endif
+ __asm__ __volatile__(
+ ".set push\n\t"
+ ".set noat\n\t"
+ /* Store $1 so we can use it */
+ STR_LONG_S " $1,"STR_LONGSIZE"(%1)\n\t"
+ /* Store the PC */
+ "1: " STR_PTR_LA " $1, 1b\n\t"
+ STR_LONG_S " $1,%0\n\t"
+ STORE_ONE_REG(2)
+ STORE_ONE_REG(3)
+ STORE_ONE_REG(4)
+ STORE_ONE_REG(5)
+ STORE_ONE_REG(6)
+ STORE_ONE_REG(7)
+ STORE_ONE_REG(8)
+ STORE_ONE_REG(9)
+ STORE_ONE_REG(10)
+ STORE_ONE_REG(11)
+ STORE_ONE_REG(12)
+ STORE_ONE_REG(13)
+ STORE_ONE_REG(14)
+ STORE_ONE_REG(15)
+ STORE_ONE_REG(16)
+ STORE_ONE_REG(17)
+ STORE_ONE_REG(18)
+ STORE_ONE_REG(19)
+ STORE_ONE_REG(20)
+ STORE_ONE_REG(21)
+ STORE_ONE_REG(22)
+ STORE_ONE_REG(23)
+ STORE_ONE_REG(24)
+ STORE_ONE_REG(25)
+ STORE_ONE_REG(26)
+ STORE_ONE_REG(27)
+ STORE_ONE_REG(28)
+ STORE_ONE_REG(29)
+ STORE_ONE_REG(30)
+ STORE_ONE_REG(31)
+ /* Restore $1 */
+ STR_LONG_L " $1,"STR_LONGSIZE"(%1)\n\t"
+ ".set pop\n\t"
+ : "=m" (regs->cp0_epc)
+ : "r" (regs->regs)
+ : "memory");
+}
+
+#endif /* _ASM_STACKTRACE_H */