ISA_v84A_A64_xml_00bet7 (old) | htmldiff from-ISA_v84A_A64_xml_00bet7 | (new) ISA_v84A_A64_xml_00bet7_OPT |
Return from subroutine, with pointer authentication. This instruction authenticates the address that is held in LR, using SP as the modifier and the specified key, branches to the authenticated address, with a hint that this instruction is a subroutine return.
Key A is used for RETAA, and key B is used for RETAB.
If the authentication passes, the PE continues execution at the target of the branch. If the authentication fails, a Translation fault is generated.
The authenticated address is not written back to LR.
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 | 1 | 0 | 0 | 1 | 0 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 1 | M | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
Z | op | A | Rn | Rm |
boolean use_key_a = (M == '0');
if !integer n =UInt(Rn);
BranchType branch_type;
integer m = UInt(Rm);
boolean pac = (A == '1');
boolean use_key_a = (M == '0');
boolean source_is_sp = ((Z == '1') && (m == 31));
if !pac && m != 0 then
UnallocatedEncoding();
elsif pac && !HavePACExt() then
UnallocatedEncoding();
case op of
when '00' branch_type = BranchType_JMP;
when '01' branch_type = BranchType_CALL;
when '10' branch_type = BranchType_RET;
otherwise UnallocatedEncoding();
if pac then
if Z == '0' && m != 31 then
UnallocatedEncoding();
if branch_type == BranchType_RET() thenthen
if n !=31 then
UnallocatedEncoding();();
n = 30;
source_is_sp = TRUE;
bits(64) target = X[30];
bits(64) modifier =[n];
if pac then
bits(64) modifier = if source_is_sp then SP[];
if use_key_a then
target =[] else X[m];
if use_key_a then
target = AuthIA(target, modifier);
else
target = AuthIB(target, modifier);(target, modifier);
if branch_type ==
BranchType_CALL then X[30] = PC[] + 4;
BranchTo(target, BranchType_RET);(target, branch_type);
Internal version only: isa v29.05, AdvSIMD v26.0, pseudocode v35.3
; Build timestamp: 2018-06-16T09:5845
Copyright © 2010-2018 ARM Limited or its affiliates. All rights reserved. This document is Non-Confidential.
ISA_v84A_A64_xml_00bet7 (old) | htmldiff from-ISA_v84A_A64_xml_00bet7 | (new) ISA_v84A_A64_xml_00bet7_OPT |