i386/ucla/src/lab4/user/readonlytext.c

   1 #include <inc/lib.h>
   2 #include <inc/x86.h>
   3
   4 void
   5 my_handler(struct UTrapframe *utf)
   6 {
   7         if (utf->utf_fault_va == (uintptr_t) my_handler
   8             && (utf->utf_err & FEC_U)
   9             && (utf->utf_err & FEC_W)
  10             && (utf->utf_err & FEC_PR))
  11                 cprintf("program text is read-only\n");
  12         else
  13                 cprintf("unexpected page fault\n");
  14         sys_env_destroy(0);
  15 }
  16
  17 asmlinkage void
  18 umain(int argc, char **argv)
  19 {
  20         set_pgfault_handler(my_handler);
  21
  22         volatile uint32_t *ptr = (volatile uint32_t *) my_handler;
  23         *ptr = *ptr;
  24
  25         cprintf("should not be reached\n");
  26 }