diff --git a/Makefile b/Makefile
index 74e454f..af4c4ca 100644
--- a/Makefile
+++ b/Makefile
@@ -343,7 +343,7 @@ grade:
 	@echo $(MAKE) clean
 	@$(MAKE) clean || \
           (echo "'make clean' failed.  HINT: Do you have another running instance of xv6?" && exit 1)
-	./grade-lab-$(LAB) $(GRADEFLAGS)
+	python3.12 ./grade-lab-$(LAB) $(GRADEFLAGS)
 
 ##
 ## FOR submissions
diff --git a/kernel/defs.h b/kernel/defs.h
index d1b6bb9..29f5a76 100644
--- a/kernel/defs.h
+++ b/kernel/defs.h
@@ -80,6 +80,7 @@ int             pipewrite(struct pipe*, uint64, int);
 int            printf(char*, ...) __attribute__ ((format (printf, 1, 2)));
 void            panic(char*) __attribute__((noreturn));
 void            printfinit(void);
+void            backtrace(void);
 
 // proc.c
 int             cpuid(void);
diff --git a/kernel/printf.c b/kernel/printf.c
index d20534c..f0a7055 100644
--- a/kernel/printf.c
+++ b/kernel/printf.c
@@ -176,3 +176,22 @@ printfinit(void)
   initlock(&pr.lock, "pr");
   pr.locking = 1;
 }
+
+void
+backtrace(void)
+{
+  printf("barcktrace:\n");
+
+  uint64 ra,fp = r_fp();//frame pointer -> address
+  uint64 pre_fp = *((uint64*)(fp - 16));
+
+  while(PGROUNDDOWN(fp)==PGROUNDDOWN(pre_fp)){
+    ra = *(uint64 *)(fp - 8);
+    printf("%p\n", (void*)ra);
+    fp = pre_fp;
+    pre_fp = *((uint64*)(fp - 16));
+  }
+
+  ra = *(uint64 *)(fp - 8);
+  printf("%p\n",(void*)ra);
+}
\ No newline at end of file
diff --git a/kernel/riscv.h b/kernel/riscv.h
index f7aaa8a..e6b00e2 100644
--- a/kernel/riscv.h
+++ b/kernel/riscv.h
@@ -338,6 +338,14 @@ r_ra()
   return x;
 }
 
+static inline uint64
+r_fp()
+{
+  uint64 x;
+  asm volatile("mv %0, s0" : "=r" (x) );
+  return x;
+}
+
 // flush the TLB.
 static inline void
 sfence_vma()
diff --git a/kernel/sysproc.c b/kernel/sysproc.c
index 3b4d5bd..651a697 100644
--- a/kernel/sysproc.c
+++ b/kernel/sysproc.c
@@ -54,6 +54,8 @@ sys_sleep(void)
   int n;
   uint ticks0;
 
+  backtrace();
+
   argint(0, &n);
   if(n < 0)
     n = 0;