user_va_to_slb_entry
slb = user_va_to_slb_entry(pm, (vm_offset_t)uaddr);
entry = user_va_to_slb_entry(pm, va);
user_entry = user_va_to_slb_entry(pm, addr);
struct slb *user_va_to_slb_entry(pmap_t pm, vm_offset_t va);