test/test62.c

   1 /* FPU state corruption test. This used to be able to crash the kernel. */
   2 #include <stdlib.h>
   3 #include <stdio.h>
   4 #include <string.h>
   5 #include <signal.h>
   6 #include <sys/wait.h>
   7 #include <machine/fpu.h>
   8
   9 #define MAX_ERROR 1
  10 #include "common.c"
  11
  12 double state = 2.0;
  13 static int count;
  14
  15 static void use_fpu(int n)
  16 {
  17   state += (double) n * 0.5;
  18 }
  19
  20 static void crashed(int sig)
  21 {
  22   exit(EXIT_SUCCESS);
  23 }
  24
  25 static void handler(int sig, int code, struct sigcontext *sc)
  26 {
  27   memset(&sc->sc_fpu_state, count, sizeof(sc->sc_fpu_state));
  28 }
  29
  30 int main(void)
  31 {
  32   int status;
  33
  34   start(62);
  35   subtest = 0;
  36
  37   signal(SIGUSR1, (void (*)(int)) handler);
  38
  39   /* Initialize the FPU state. This state is inherited, too. */
  40   use_fpu(-1);
  41
  42   for (count = 0; count <= 255; count++) {
  43         switch (fork()) {
  44         case -1:
  45                 e(1);
  46
  47                 break;
  48
  49         case 0:
  50                 signal(SIGFPE, crashed);
  51
  52                 /* Load bad state into the kernel. */
  53                 if (kill(getpid(), SIGUSR1)) e(2);
  54
  55                 /* Let the kernel restore the state. */
  56                 use_fpu(count);
  57
  58                 exit(EXIT_SUCCESS);
  59
  60         default:
  61                 /* We cannot tell exactly whether what happened is correct or
  62                  * not -- certainly not in a platform-independent way. However,
  63                  * if the whole system keeps running, that's good enough.
  64                  */
  65                 (void) wait(&status);
  66         }
  67   }
  68
  69   if (state <= 1.4 || state >= 1.6) e(3);
  70
  71   quit();
  72
  73   return 0;
  74 }