UAO User Access Override when FEAT_UAO is implemented and FEAT_AA64 is implemented Allows access to the User Access Override bit. PSTATE UAO is a 64-bit register. 63 24 63:24 Reserved, RES0. UAO 23 23 23 User Access Override. The Effective value of PSTATE.UAO is 0 when execution is at EL0. The Effective value of PSTATE.UAO is 1 when any of the following is true: Execution is at EL1, and HCR_EL2.{NV, NV1} is {1, 1}. Execution is at EL2, and the Effective value of HCR_EL2.{E2H, TGE} is not {1, 1}. Execution is at EL3. 0b0 Explicit Memory Effects generated by unprivileged memory access instructions and described as unprivileged are unprivileged. 0b1 Explicit Memory Effects generated by unprivileged memory access instructions and described as unprivileged are privileged. 22 0 22:0 Reserved, RES0. For more information about the operation of the MSR (immediate) accessor, see 'MSR (immediate)'. MRS <Xt>, UAO if !(IsFeatureImplemented(FEAT_UAO) && IsFeatureImplemented(FEAT_AA64)) then Undefined(); elsif PSTATE.EL == EL0 then Undefined(); elsif PSTATE.EL == EL1 then X{64}(t) = Zeros{40} :: PSTATE.UAO :: Zeros{23}; elsif PSTATE.EL == EL2 then X{64}(t) = Zeros{40} :: PSTATE.UAO :: Zeros{23}; elsif PSTATE.EL == EL3 then X{64}(t) = Zeros{40} :: PSTATE.UAO :: Zeros{23}; end; MSR UAO, <Xt> if !(IsFeatureImplemented(FEAT_UAO) && IsFeatureImplemented(FEAT_AA64)) then Undefined(); elsif PSTATE.EL == EL0 then Undefined(); elsif PSTATE.EL == EL1 then PSTATE.UAO = X{64}(t)[23]; elsif PSTATE.EL == EL2 then PSTATE.UAO = X{64}(t)[23]; elsif PSTATE.EL == EL3 then PSTATE.UAO = X{64}(t)[23]; end; MSR UAO, #<imm> 2026-03-26 20:27:25 2026-03_rel