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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:

  • In the general-purpose register that is specified by <Xd> for PACIA and PACIZA.
  • In X17, for PACIA1716.
  • In X30, for PACIASP and PACIAZ.

The modifier is:

  • In the general-purpose register or stack pointer that is specified by <Xn|SP> for PACIA.
  • The value zero, for PACIZA and PACIAZ.
  • In X16, for PACIA1716.
  • In SP, for PACIASP.

It has encodings from 2 classes: Integer and System

Integer
(Armv8.3)

313029282726252423222120191817161514131211109876543210
110110101100000100Z000RnRd

PACIA (Z == 0)

PACIA <Xd>, <Xn|SP>

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

PACIZA <Xd>

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

if !HavePACExt() then
    UNDEFINED;

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

System
(Armv8.3)

313029282726252423222120191817161514131211109876543210
1101010100000011001000x100x11111
CRmop2

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;

case CRm:op2 of
    when '0011 000'    // PACIAZ 
        d = 30;
        n = 31;
    when '0011 001'    // PACIASP
        d = 30;
        source_is_sp = TRUE;
        if HaveBTIExt() then
            // Check for branch target compatibility between PSTATE.BTYPE
            // and implicit branch target of PACIASP instruction.
            - = BTypeCompatible_PACIXSP();

    when '0001 000'    // PACIA1716
        d = 17;
        n = 16;
    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";

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 HavePACExt() then
    if source_is_sp then
        X[d] = AddPACIA(X[d], SP[]);
    else
        X[d] = AddPACIA(X[d], X[n]);
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