Branch 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 branches to the authenticated address.
The modifier is:
Key A is used for BRAA and BRAAZ. Key B is used for BRAB and BRABZ.
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 the general-purpose register.
This instruction provides a hint that this is not a subroutine call or return.
| 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 | 0 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 1 | M | Rn | Rm | ||||||||
| op | op2 | A | |||||||||||||||||||||||||||||
BRAAZ <Xn>
BRABZ <Xn>
if !IsFeatureImplemented(FEAT_PAuth) then EndOfDecode(Decode_UNDEF); end; if Z == '0' && Rm != '11111' then EndOfDecode(Decode_UNDEF); end; let n : integer{} = UInt(Rn); let m : integer{} = UInt(Rm); let use_key_a : boolean = (M == '0'); let source_is_sp : boolean = ((Z == '1') && (m == 31)); let auth_then_branch : boolean = 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. |
var target : bits(64) = X{}(n); let modifier : bits(64) = if source_is_sp then SP{64}() else X{64}(m); if use_key_a then target = AuthIA(target, modifier, auth_then_branch); else target = AuthIB(target, modifier, auth_then_branch); end; // Value in BTypeNext will be used to set PSTATE.BTYPE if InGuardedPage then if n == 16 || n == 17 then BTypeNext = '01'; else BTypeNext = '11'; end; else BTypeNext = '01'; end; let branch_conditional : boolean = FALSE; BranchTo{64}(target, BranchType_INDIR, branch_conditional);
2026-03_rel 2026-03-26 20:48:11
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