BRAA, BRAAZ, BRAB, BRABZ -- A64

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.

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.

Integer
(FEAT_PAuth)

Decode for all variants of this encoding

if !IsFeatureImplemented(FEAT_PAuth) then EndOfDecode(Decode_UNDEF); if Z == '0' && Rm != '11111' then EndOfDecode(Decode_UNDEF); constant integer n = UInt(Rn); constant integer m = UInt(Rm); constant boolean use_key_a = (M == '0'); constant boolean source_is_sp = ((Z == '1') && (m == 31)); constant boolean auth_then_branch = TRUE;

Assembler Symbols

<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.

Operation

bits(64) target = X[n, 64]; constant bits(64) modifier = if source_is_sp then SP[64] else X[m, 64]; if use_key_a then target = AuthIA(target, modifier, auth_then_branch); else target = AuthIB(target, modifier, auth_then_branch); // Value in BTypeNext will be used to set PSTATE.BTYPE if InGuardedPage then if n == 16 || n == 17 then BTypeNext = '01'; else BTypeNext = '11'; else BTypeNext = '01'; constant boolean branch_conditional = FALSE; BranchTo(target, BranchType_INDIR, branch_conditional);

Internal version only: aarchmrs v2024-12_rel, pseudocode v2024-12_rel ; Build timestamp: 2024-12-15T22:18

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