Lab traps: backtrace

foyoodo · Mar 21, 2021 · f70996c · f70996c
1 parent 2455162
commit f70996c
Show file tree

Hide file tree

Showing 4 changed files with 27 additions and 0 deletions.
diff --git a/kernel/defs.h b/kernel/defs.h
@@ -80,6 +80,7 @@ int             pipewrite(struct pipe*, uint64, int);
 void            printf(char*, ...);
 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
@@ -132,3 +132,18 @@ printfinit(void)
   initlock(&pr.lock, "pr");
   pr.locking = 1;
 }
+
+void
+backtrace(void)
+{
+  printf("backtrace:\n");
+
+  uint64 fp = r_fp();
+  uint64 bottom = PGROUNDUP(fp);
+
+  while (fp < bottom) {
+    uint64 ra = *(uint64*)(fp - 8);
+    printf("%p\n", ra);
+    fp = *(uint64*)(fp - 16);
+  }
+}
diff --git a/kernel/riscv.h b/kernel/riscv.h
@@ -311,6 +311,14 @@ 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
@@ -70,6 +70,9 @@ sys_sleep(void)
     sleep(&ticks, &tickslock);
   }
   release(&tickslock);
+
+  backtrace();
+
   return 0;
 }