struct desc_struct def_ldt;
unsigned long *lp, *lp2;

asm volatile ( "sgdt __gdt+2" );

lp = (unsigned long *)(__gdt[1] + current->tss.ldt );

lp2 = (unsigned long *)(((*lp >> 16) & 0x0000ffff)
           | (*(lp+1) & 0xff000000)
           | ((*(lp+1) << 16) & 0x00ff0000));

def_ldt.a = *lp2;
def_ldt.b = *(lp2+1);