Index

PACIA, PACIA1716, PACIASP, PACIAZ, PACIZA

Pointer Authentication Code for Instruction address, using key A. This instruction computes and inserts a pointer authentication code for an instruction address, using a modifier and key A.

The address is:

The modifier is:

If FEAT_PAuth_LR is implemented and PSTATE.PACM is 1, then PACIA1716 and PACIASP include a second modifier that is:

A PACIASP instruction has an implicit BTI instruction. The implicit BTI instruction of a PACIASP instruction is always compatible with PSTATE.BTYPE == 0b01 and PSTATE.BTYPE == 0b10. Controls in SCTLR_ELx configure whether the implicit BTI instruction of a PACIASP instruction is compatible with PSTATE.BTYPE == 0b11. For more information, see PSTATE.BTYPE.

It has encodings from 2 classes: Integer and System

Integer
(FEAT_PAuth)

31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
1 1 0 1 1 0 1 0 1 1 0 0 0 0 0 1 0 0 Z 0 0 0 Rn Rd

PACIA (Z == 0)

PACIA <Xd>, <Xn|SP>

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

PACIZA <Xd>

boolean source_is_sp = FALSE;
boolean pacia1716 = FALSE;
integer d = UInt(Rd);
integer n = UInt(Rn);

if !IsFeatureImplemented(FEAT_PAuth) then
    UNDEFINED;

if Z == '0' then // PACIA
    if n == 31 then source_is_sp = TRUE;
else // PACIZA
    if n != 31 then UNDEFINED;

System
(FEAT_PAuth)

31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
1 1 0 1 0 1 0 1 0 0 0 0 0 0 1 1 0 0 1 0 0 0 x 1 0 0 x 1 1 1 1 1
CRm op2

PACIA1716 (CRm == 0001 && op2 == 000)

PACIA1716

PACIASP (CRm == 0011 && op2 == 001)

PACIASP

PACIAZ (CRm == 0011 && op2 == 000)

PACIAZ

integer d;
integer n;
boolean source_is_sp = FALSE;
boolean pacia1716 = FALSE;

case CRm:op2 of
    when '0011 000'    // PACIAZ
        d = 30;
        n = 31;
    when '0011 001'    // PACIASP
        d = 30;
        source_is_sp = TRUE;
        if IsFeatureImplemented(FEAT_BTI) then
            // Check for branch target compatibility between PSTATE.BTYPE
            // and implicit branch target of PACIASP instruction.
            SetBTypeCompatible(BTypeCompatible_PACIXSP());
    when '0001 000'    // PACIA1716
        d = 17;
        n = 16;
        pacia1716 = TRUE;
    when '0001 010' SEE "PACIB";
    when '0001 100' SEE "AUTIA";
    when '0001 110' SEE "AUTIB";
    when '0011 01x' SEE "PACIB";
    when '0011 10x' SEE "AUTIA";
    when '0011 11x' SEE "AUTIB";
    when '0000 111' SEE "XPACLRI";
    otherwise SEE "HINT";

Assembler Symbols

<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.

Operation

if IsFeatureImplemented(FEAT_PAuth) then
    if source_is_sp then
        if IsFeatureImplemented(FEAT_PAuth_LR) && PSTATE.PACM == '1' then
            X[d, 64] = AddPACIA2(X[d, 64], SP[], PC64);
        else
            X[d, 64] = AddPACIA(X[d, 64], SP[]);
    else
        if IsFeatureImplemented(FEAT_PAuth_LR) && PSTATE.PACM == '1' && pacia1716 then
            X[d, 64] = AddPACIA2(X[d, 64], X[n, 64], X[15, 64]);
        else
            X[d, 64] = AddPACIA(X[d, 64], X[n, 64]);