pacdb

Pointer Authentication Code for Data Address (Key B)

PACDB <Xd>, <Xn>

Signs a data address using Key B.

Details

Computes a pointer authentication code for a data address using Key B and the modifier in Xn, storing the signed value in Xd. This is an AArch64-only instruction used for data-pointer integrity. No general-purpose condition flags are set; authentication failure (during later verification) generates an exception.

Pseudocode Operation

Xd ← AddPAC(Xd, Xn, Key_B, DataAddressType)

Example

PACDB x0, x1

Encoding

Binary Layout
1
1
0
11010110
00001
00
0
011
Rn
Rd
 
Format Data Processing
Opcode 0xDAC10C00
Extension PAC (Security)

Operands

  • Xd
    Destination 64-bit integer register
  • Xn
    Modifier

Reference (Arm A64 ISA)

Instruction Forms

Encoding Instruction ISA Bit pattern
0xDAC10C00 PACDB <Xd>, <Xn|SP> A64 1 | 1 | 0 | 11010110 | 00001 | 00 | 0 | 011 | Rn | Rd

Description

Pointer Authentication Code for Data address, using key B. This instruction computes and inserts a pointer authentication code for 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:

Operation

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