tests/tcg/aarch64/pauth-5.c

   1 #include <assert.h>
   2
   3 static int x;
   4
   5 int main()
   6 {
   7     int *p0 = &x, *p1, *p2, *p3;
   8     unsigned long salt = 0;
   9
  10     /*
  11      * With TBI enabled and a 48-bit VA, there are 7 bits of auth, and so
  12      * a 1/128 chance of auth = pac(ptr,key,salt) producing zero.
  13      * Find a salt that creates auth != 0.
  14      */
  15     do {
  16         salt++;
  17         asm("pacda %0, %1" : "=r"(p1) : "r"(salt), "0"(p0));
  18     } while (p0 == p1);
  19
  20     /*
  21      * This pac must fail, because the input pointer bears an encryption,
  22      * and so is not properly extended within bits [55:47].  This will
  23      * toggle bit 54 in the output...
  24      */
  25     asm("pacda %0, %1" : "=r"(p2) : "r"(salt), "0"(p1));
  26
  27     /* ... so that the aut must fail, setting bit 53 in the output ... */
  28     asm("autda %0, %1" : "=r"(p3) : "r"(salt), "0"(p2));
  29
  30     /* ... which means this equality must not hold. */
  31     assert(p3 != p0);
  32     return 0;
  33 }