RtlpGetNonLegacyXStateAreaLength

NTSTATUS __stdcall RtlpGetNonLegacyXStateAreaLength(INT64 a1){
  if( (KUSER_SHARED_DATA.XState._bf_0 & 2) != 0 )
    a1 &= KUSER_SHARED_DATA.XState.EnabledFeatures | KUSER_SHARED_DATA.XState.EnabledUserVisibleSupervisorFeatures | 0x8000000000000000ui64;
  return RtlpGetEntireXStateAreaLength(a1) - 512;
}

Referenced by:

KiInitializeUserApc