pacib

Pointer Authentication Code (Inst B)

PACIB <Xd>, <Xn|SP>

Signs a pointer in Xd using Key B.

Pseudocode Operation

modifier ← Xn | SP
Xd ← AddPAC(Xd, modifier, key_b, instruction_key)

Example

PACIB x0, x1

Encoding

Binary Layout

1

31

1

30

0

29

11010110

28:21

00001

20:16

00

15:14

0

13

001

12:10

Rn

9:5

Rd

4:0

 

Format Data Processing

Opcode 0xDAC10400

Extension PAC (Security)

Operands

• Xd
  Ptr
• Xn
  Modifier

Related

Other forms of pacib

• pacib Pointer Authentication Code for Instruction…

More in PAC (Security)

Reference

View in Arm A64 ISA Reference ↗ Arm A64 ISA

Instruction Forms

Encoding	Instruction		ISA		Bit pattern
0xDAC10400	PACIB <Xd>, <Xn|SP>		A64		1 | 1 | 0 | 11010110 | 00001 | 00 | 0 | 001 | Rn | Rd

Description

Pointer Authentication Code for Instruction address, using key B. This instruction computes and inserts a pointer authentication code for an instruction address, using a modifier and key B. The address is: The modifier is: If FEAT_PAuth_LR is implemented and PSTATE.PACM is 1, then PACIB1716 and PACIBSP include a second modifier that is: A PACIBSP instruction has an implicit BTI instruction. The implicit BTI instruction of a PACIBSP instruction is always compatible with PSTATE.BTYPE == 0b01 and PSTATE.BTYPE == 0b10. Controls in SCTLR_ELx configure whether the implicit BTI instruction of a PACIBSP instruction is compatible with PSTATE.BTYPE == 0b11. For more information, see PSTATE.BTYPE.

Operation

if IsFeatureImplemented(FEAT_PAuth) then
    if source_is_sp then
        if IsFeatureImplemented(FEAT_PAuth_LR) && PSTATE.PACM == '1' then
            X[d, 64] = AddPACIB2(X[d, 64], SP[], PC64);
        else
            X[d, 64] = AddPACIB(X[d, 64], SP[]);
    else
        if IsFeatureImplemented(FEAT_PAuth_LR) && PSTATE.PACM == '1' && pacib1716 then
            X[d, 64] = AddPACIB2(X[d, 64], X[n, 64], X[15, 64]);
        else
            X[d, 64] = AddPACIB(X[d, 64], X[n, 64]);