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 } 62