LXR qemu/tests/tcg/aarch64/pauth-5.c

   1#include <assert.h>
   2
   3static int x;
   4
   5int 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}
  34