--- zzzz-none-000/linux-3.10.107/arch/mips/kernel/process.c	2017-06-27 09:49:32.000000000 +0000
+++ vr9-7490-729/linux-3.10.107/arch/mips/kernel/process.c	2021-11-10 11:53:54.000000000 +0000
@@ -42,6 +42,9 @@
 #include <asm/inst.h>
 #include <asm/stacktrace.h>
 
+/*--- #define STACK_TRC(args...) printk(KERN_INFO args) ---*/
+#define STACK_TRC(args...)
+
 #ifdef CONFIG_HOTPLUG_CPU
 void arch_cpu_idle_dead(void)
 {
@@ -60,9 +63,6 @@
 
 	/* New thread loses kernel privileges. */
 	status = regs->cp0_status & ~(ST0_CU0|ST0_CU1|ST0_FR|KU_MASK);
-#ifdef CONFIG_64BIT
-	status |= test_thread_flag(TIF_32BIT_REGS) ? 0 : ST0_FR;
-#endif
 	status |= KU_USER;
 	regs->cp0_status = status;
 	clear_used_math();
@@ -475,7 +475,7 @@
 	 * thread_saved_pc() and get_wchan() are not reliable.
 	 */
 	if (schedule_mfi.pc_offset < 0)
-		printk("Can't analyze schedule() prologue at %p\n", schedule);
+		printk(KERN_WARNING "Can't analyze schedule() prologue at %p\n", schedule);
 
 	return 0;
 }
@@ -562,11 +562,14 @@
 		 * same value.
 		 */
 		pc = pc != *ra ? *ra : 0;
-	else
+	else {
 		pc = ((unsigned long *)(*sp))[info.pc_offset];
+		STACK_TRC("%s %d: pc %lx pc_offset = %d\n", __FUNCTION__, __LINE__, pc, info.pc_offset);
+	}
 
 	*sp += info.frame_size;
 	*ra = 0;
+	STACK_TRC("%s %d: %lx %d\n", __FUNCTION__, __LINE__, pc, __kernel_text_address(pc));
 	return __kernel_text_address(pc) ? pc : 0;
 }
 EXPORT_SYMBOL(unwind_stack_by_address);