regress/sys/uvm/stack_exec/tramptest.c

   1 /* $NetBSD$ */
   2
   3 #include <stdlib.h>
   4 #include <pthread.h>
   5 #include <signal.h>
   6
   7 /*
   8  * This test checks whether processes/threads get execute permission
   9  * on the stack if needed, in particular for multiple threads.
  10  * It depends on the fact that gcc puts trampoline code for
  11  * nested functions on the stack and requests execution permission
  12  * for that address internally, at least on some architectures.
  13  * (On the other architectures, the test is just insignificant.)
  14  * Actually, it would be better if gcc wouldn't use stack trampolines,
  15  * at all, but for now it allows for an easy portable check whether the
  16  * kernel handles permissions correctly.
  17  */
  18
  19 void
  20 buserr(int s)
  21 {
  22
  23         exit(1);
  24 }
  25
  26 int
  27 main()
  28 {
  29         pthread_t t1, t2;
  30
  31         void *mist(void *p)
  32         {
  33
  34                 return (0);
  35         }
  36
  37         signal(SIGBUS, buserr);
  38
  39         pthread_create(&t1, 0, mist, 0);
  40         pthread_create(&t2, 0, mist, 0);
  41         pthread_join(t1, 0);
  42         pthread_join(t2, 0);
  43         exit(0);
  44 }