AUTDB, AUTDZB

Authenticate data address, using key B

This instruction authenticates a data address, using a modifier and key B.

The address is in the general-purpose register that is specified by <Xd>.

The modifier is:

  • In the general-purpose register or stack pointer that is specified by <Xn|SP> for AUTDB.
  • The value zero, for AUTDZB.

    • If the authentication passes, the upper bits of the address are restored to enable subsequent use of the address. For information on behavior if the authentication fails, see Faulting on pointer authentication.

    Encoding: Integer

    Variants: FEAT_PAuth (ARMv8.3)

    313029282726252423222120191817161514131211109876543210
    110110101100000100111
    sfSopcode2ZRnRd

    AUTDB (Z == 0)

    AUTDB <Xd>, <Xn|SP>

    AUTDZB (Z == 1 && Rn == 11111)

    AUTDZB <Xd>

    Decoding algorithm

    if !IsFeatureImplemented(FEAT_PAuth) then EndOfDecode(Decode_UNDEF);
if Z == '1' && Rn != '11111' then EndOfDecode(Decode_UNDEF);
constant boolean auth_combined = FALSE;

constant integer d = UInt(Rd);
constant integer n = UInt(Rn);

constant boolean source_is_sp = Z == '0' && n == 31;

    Operation

    if source_is_sp then
    X[d, 64] = AuthDB(X[d, 64], SP[64], auth_combined);
else
    X[d, 64] = AuthDB(X[d, 64], X[n, 64], auth_combined);

    Explanations

    <Xd>: Is the 64-bit name of the general-purpose destination register, encoded in the "Rd" field.
    <Xn|SP>: Is the 64-bit name of the general-purpose source register or stack pointer, encoded in the "Rn" field.