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. Key B is used for BLRAB and BLRABZ.
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.
| 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 | op2 | A | |||||||||||||||||||||||||||||
if !IsFeatureImplemented(FEAT_PAuth) then UNDEFINED; if Z == '0' && Rm != '11111' then UNDEFINED; integer n = UInt(Rn); integer m = UInt(Rm); boolean use_key_a = (M == '0'); boolean source_is_sp = ((Z == '1') && (m == 31)); boolean auth_then_branch = 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, 64]; bits(64) modifier = if source_is_sp then SP[] else X[m, 64]; if use_key_a then target = AuthIA(target, modifier, auth_then_branch); else target = AuthIB(target, modifier, auth_then_branch); if IsFeatureImplemented(FEAT_GCS) && GCSPCREnabled(PSTATE.EL) then AddGCSRecord(PC64 + 4); // Value in BTypeNext will be used to set PSTATE.BTYPE BTypeNext = '10'; X[30, 64] = PC64 + 4; boolean branch_conditional = FALSE; BranchTo(target, BranchType_INDCALL, branch_conditional);
Internal version only: aarchmrs v2024-03_relA, pseudocode v2024-03_rel, sve v2024-03_rel ; Build timestamp: 2024-03-26T09:45
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