alarm task finished

kernel/sysproc.c

@@ -93,3 +93,28 @@ sys_uptime(void)
   release(&tickslock);
   return xticks;
 }
+
+uint64
+sys_sigalarm(void)
+{
+  int alarm_cnt;
+  uint64 addr;
+  struct proc *p = myproc();
+  argint(0, &alarm_cnt);
+  argaddr(1, &addr);
+
+  p->inter_cnt = 0;
+  p->handler = addr;
+  p->alarm_cnt = alarm_cnt;
+
+  return 0;
+}
+
+uint64
+sys_sigreturn(void)
+{
+  struct proc* p = myproc();
+  *p->trapframe = *p->pre_trapframe;
+  p->inter_cnt = 0;
+  return p->pre_trapframe->a0;
+}