v4.19.13 snapshot.
diff --git a/arch/mips/kernel/stacktrace.c b/arch/mips/kernel/stacktrace.c
new file mode 100644
index 0000000..7c7c902
--- /dev/null
+++ b/arch/mips/kernel/stacktrace.c
@@ -0,0 +1,92 @@
+/*
+ * Stack trace management functions
+ *
+ * Copyright (C) 2006 Atsushi Nemoto <anemo@mba.ocn.ne.jp>
+ */
+#include <linux/sched.h>
+#include <linux/sched/debug.h>
+#include <linux/sched/task_stack.h>
+#include <linux/stacktrace.h>
+#include <linux/export.h>
+#include <asm/stacktrace.h>
+
+/*
+ * Save stack-backtrace addresses into a stack_trace buffer:
+ */
+static void save_raw_context_stack(struct stack_trace *trace,
+ unsigned long reg29, int savesched)
+{
+ unsigned long *sp = (unsigned long *)reg29;
+ unsigned long addr;
+
+ while (!kstack_end(sp)) {
+ addr = *sp++;
+ if (__kernel_text_address(addr) &&
+ (savesched || !in_sched_functions(addr))) {
+ if (trace->skip > 0)
+ trace->skip--;
+ else
+ trace->entries[trace->nr_entries++] = addr;
+ if (trace->nr_entries >= trace->max_entries)
+ break;
+ }
+ }
+}
+
+static void save_context_stack(struct stack_trace *trace,
+ struct task_struct *tsk, struct pt_regs *regs, int savesched)
+{
+ unsigned long sp = regs->regs[29];
+#ifdef CONFIG_KALLSYMS
+ unsigned long ra = regs->regs[31];
+ unsigned long pc = regs->cp0_epc;
+
+ if (raw_show_trace || !__kernel_text_address(pc)) {
+ unsigned long stack_page =
+ (unsigned long)task_stack_page(tsk);
+ if (stack_page && sp >= stack_page &&
+ sp <= stack_page + THREAD_SIZE - 32)
+ save_raw_context_stack(trace, sp, savesched);
+ return;
+ }
+ do {
+ if (savesched || !in_sched_functions(pc)) {
+ if (trace->skip > 0)
+ trace->skip--;
+ else
+ trace->entries[trace->nr_entries++] = pc;
+ if (trace->nr_entries >= trace->max_entries)
+ break;
+ }
+ pc = unwind_stack(tsk, &sp, pc, &ra);
+ } while (pc);
+#else
+ save_raw_context_stack(trace, sp, savesched);
+#endif
+}
+
+/*
+ * Save stack-backtrace addresses into a stack_trace buffer.
+ */
+void save_stack_trace(struct stack_trace *trace)
+{
+ save_stack_trace_tsk(current, trace);
+}
+EXPORT_SYMBOL_GPL(save_stack_trace);
+
+void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
+{
+ struct pt_regs dummyregs;
+ struct pt_regs *regs = &dummyregs;
+
+ WARN_ON(trace->nr_entries || !trace->max_entries);
+
+ if (tsk != current) {
+ regs->regs[29] = tsk->thread.reg29;
+ regs->regs[31] = 0;
+ regs->cp0_epc = tsk->thread.reg31;
+ } else
+ prepare_frametrace(regs);
+ save_context_stack(trace, tsk, regs, tsk == current);
+}
+EXPORT_SYMBOL_GPL(save_stack_trace_tsk);