VALID_USER_GSEL32
!(VALID_USER_GSEL32(scp->sc_gs) && pcb->pcb_gs != 0))
!(VALID_USER_GSEL32(gr[_REG32_GS]) && pcb->pcb_gs != 0))
!(VALID_USER_GSEL32(regs->r_gs) && pcb->pcb_gs != 0))
!(VALID_USER_GSEL32(scp->sc_gs) && pcb->pcb_gs != 0))