diff --git a/lab/kern/monitor.c b/lab/kern/monitor.c
index 4e00796..a8d5617 100644
--- a/lab/kern/monitor.c
+++ b/lab/kern/monitor.c
@@ -59,6 +59,24 @@ int
 mon_backtrace(int argc, char **argv, struct Trapframe *tf)
 {
 	// Your code here.
+	int
+mon_backtrace(int argc, char **argv, struct Trapframe *tf)
+{
+	
+	uint32_t *ebp;
+ 	ebp = (uint32_t *)read_ebp();
+	cprintf("Stack backtrace:\n");
+	while(ebp!=0){
+		cprintf("  ebp %08x",ebp);
+		cprintf("  eip %08x  args",*(ebp+1));
+		cprintf("  args");
+		cprintf(" %08x", *(ebp+2));
+		cprintf(" %08x", *(ebp+3));
+		cprintf(" %08x", *(ebp+4));
+		cprintf(" %08x", *(ebp+5));
+		cprintf(" %08x\n", *(ebp+6));
+	}
+
 	return 0;
 }