Base Instructions | SIMD&FP Instructions | SVE Instructions | SME Instructions | Index by Encoding | Shared Pseudocode | Proprietary Notice

## RETAA, RETAB

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. Key B is used for RETAB.

If the authentication passes, the PE continues execution at the target of the branch. For information on behavior if the authentication fails, see Faulting on pointer authentication.

The authenticated address is not written back to LR.

### 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 | 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

#### RETAA (M == 0)

RETAA

#### RETAB (M == 1)

RETAB

boolean use_key_a = (M == '0'); if !HavePACExt() then UNDEFINED;

### Operation

GCSInstruction inst_type; bits(64) target = X[30, 64]; bits(64) modifier = SP[]; if use_key_a then target = AuthIA(target, modifier, TRUE); else target = AuthIB(target, modifier, TRUE); if HaveGCS() && GCSPCREnabled(PSTATE.EL) then if use_key_a then inst_type = GCSInstType_PRETAA; else inst_type = GCSInstType_PRETAB; target = LoadCheckGCSRecord(target, inst_type); SetCurrentGCSPointer(GetCurrentGCSPointer() + 8); // Value in BTypeNext will be used to set PSTATE.BTYPE BTypeNext = '00'; BranchTo(target, BranchType_RET, FALSE);

Base Instructions | SIMD&FP Instructions | SVE Instructions | SME Instructions | Index by Encoding | Shared Pseudocode | Proprietary Notice

Internal version only: isa v33.64, AdvSIMD v29.12, pseudocode v2023-06_rel, sve v2023-06_rel ; Build timestamp: 2023-07-04T19:42

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