Optical logic gates are key elements in all-optical circuits and computing. However, the footprints of current optical logic gates are still on micrometer scale. There remains challenging for further miniaturization of the logic gates to nanometer scale. In this paper, a simple scheme for realizing ultra-compact universal linear-optical logic gates is proposed. All common logic gates (AND, OR, NOT, NAND, NOR, XOR, and XNOR) encoded via binary phase shift keying are achieved by using single rectangle plasmonic slot nanoantenna with a footprint of 200 nm by 50 nm, which considerably shrinks the dimensions of the device.