regress/sys/uvm/stack_noexec/tramptest.c

   1 /* $NetBSD: tramptest.c,v 1.1 2003/12/10 13:24:59 drochner Exp $ */
   2
   3 #include <stdlib.h>
   4 #include <signal.h>
   5
   6 /*
   7  * This test checks that the stack has no execute permission.
   8  * It depends on the fact that gcc puts trampoline code for
   9  * nested functions on the stack, at least on some architectures.
  10  * (On the other architectures, the test will fail, as on platforms
  11  * where execution permissions cannot be controlled.)
  12  * Actually, it would be better if gcc wouldn't use stack trampolines,
  13  * at all, but for now it allows for an easy portable check whether the
  14  * stack is executable.
  15  */
  16
  17 void
  18 __enable_execute_stack()
  19 {
  20         /* replace gcc's internal function by a noop */
  21 }
  22
  23 void
  24 buserr(int s, siginfo_t *si, void *ctx)
  25 {
  26
  27         if (s != SIGSEGV || si->si_code != SEGV_ACCERR)
  28                 exit(2);
  29
  30         exit(0);
  31 }
  32
  33 void (*f)(void);
  34
  35 void do_f()
  36 {
  37
  38         (*f)();
  39 }
  40
  41 int
  42 main()
  43 {
  44         struct sigaction sa;
  45
  46         void mist()
  47         {
  48
  49                 return;
  50         }
  51
  52         sa.sa_sigaction = buserr;
  53         sigemptyset(&sa.sa_mask);
  54         sa.sa_flags = SA_SIGINFO;
  55         sigaction(SIGSEGV, &sa, 0);
  56
  57         f = mist;
  58         do_f();
  59
  60         exit(1);
  61 }