tests/tcg/aarch64/pauth-2.c

   1 #include <stdint.h>
   2 #include <assert.h>
   3
   4 asm(".arch armv8.4-a");
   5
   6 void do_test(uint64_t value)
   7 {
   8     uint64_t salt1, salt2;
   9     uint64_t encode, decode;
  10
  11     /*
  12      * With TBI enabled and a 48-bit VA, there are 7 bits of auth,
  13      * and so a 1/128 chance of encode = pac(value,key,salt) producing
  14      * an auth for which leaves value unchanged.
  15      * Iterate until we find a salt for which encode != value.
  16      */
  17     for (salt1 = 1; ; salt1++) {
  18         asm volatile("pacda %0, %2" : "=r"(encode) : "0"(value), "r"(salt1));
  19         if (encode != value) {
  20             break;
  21         }
  22     }
  23
  24     /* A valid salt must produce a valid authorization.  */
  25     asm volatile("autda %0, %2" : "=r"(decode) : "0"(encode), "r"(salt1));
  26     assert(decode == value);
  27
  28     /*
  29      * An invalid salt usually fails authorization, but again there
  30      * is a chance of choosing another salt that works.
  31      * Iterate until we find another salt which does fail.
  32      */
  33     for (salt2 = salt1 + 1; ; salt2++) {
  34         asm volatile("autda %0, %2" : "=r"(decode) : "0"(encode), "r"(salt2));
  35         if (decode != value) {
  36             break;
  37         }
  38     }
  39
  40     /* The VA bits, bit 55, and the TBI bits, should be unchanged.  */
  41     assert(((decode ^ value) & 0xff80ffffffffffffull) == 0);
  42
  43     /*
  44      * Bits [54:53] are an error indicator based on the key used;
  45      * the DA key above is keynumber 0, so error == 0b01.  Otherwise
  46      * bit 55 of the original is sign-extended into the rest of the auth.
  47      */
  48     if ((value >> 55) & 1) {
  49         assert(((decode >> 48) & 0xff) == 0b10111111);
  50     } else {
  51         assert(((decode >> 48) & 0xff) == 0b00100000);
  52     }
  53 }
  54
  55 int main()
  56 {
  57     do_test(0);
  58     do_test(-1);
  59     do_test(0xda004acedeadbeefull);
  60     return 0;
  61 }