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Branch with Link to Register, with pointer authentication. This instruction authenticates the address in the general-purpose register that is specified by <Xn>, using a modifier and the specified key, and calls a subroutine at the authenticated address, setting register X30 to PC+4.
The modifier is:
Key A is used for BLRAA and BLRAAZ, and key B is used for BLRAB and BLRABZ.
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 the general-purpose register.
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 | Z | 0 | 0 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 1 | M | Rn | Rm | ||||||||
op | A |
BLRAAZ <Xn>
BLRABZ <Xn>
integer n = UInt(Rn);
integer m =(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 !if !pac && m != 0 then
UNDEFINED;
elsif pac && !HavePACExt() then
UNDEFINED;
case op of
when '00' branch_type = BranchType_INDIR;
when '01' branch_type = BranchType_INDCALL;
when '10' branch_type = BranchType_RET;
otherwise UNDEFINED;
if pac then
if Z == '0' && m != 31 then
UNDEFINED;
if branch_type == BranchType_RET() then
UNDEFINED;
if Z == '0' && m != 31 then
UNDEFINED;then
if n != 31 then UNDEFINED;
n = 30;
source_is_sp = TRUE;
<Xn> | Is the 64-bit name of the general-purpose register holding the address to be branched to, encoded in the "Rn" field. |
<Xm|SP> | Is the 64-bit name of the general-purpose source register or stack pointer holding the modifier, encoded in the "Rm" field. |
bits(64) target = X[n];
bits(64) modifier = if source_is_sp thencase branch_type of
when BranchType_INDIR
if InGuardedPage then
if n == 16 || n == 17 then
BTypeNext = '01';
else
BTypeNext = '11';
else
BTypeNext = '01';
when BranchType_INDCALL
BTypeNext = '10';
when BranchType_RET
BTypeNext = '00';
if pac then
bits(64) modifier = if source_is_sp then SP[] else X[m];
if use_key_a then
target = AuthIA(target, modifier);
else
target = AuthIB(target, modifier);(target, modifier);
if branch_type ==
BranchType_INDCALL then X[30] = PC[] + 4;
BranchTo(target, BranchType_INDCALL);(target, branch_type);
Internal version only: isa v30.25, AdvSIMD v27.01, pseudocode v85-xml-00bet8_rc3
; Build timestamp: 2018-09-13T13:2504
Copyright © 2010-2018 ARM Limited or its affiliates. All rights reserved. This document is Non-Confidential.
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