The user virtual address space for x86-64 with Linux is 47 bit long. Which essentially means that Linux can map a process with around ~128 TB virtual address range. 

However, what confuses me that x86-64 architecture supports ISA defined 4-level hierarchical page table (arranged as radix-tree) for each process. The root of the page table can only map up to 512 GB of contiguous virtual address space. So how Linux can support more than 512GB of virtual address range? Does it uses multiple page tables for each process? If yes, then for a process what should the CR3 (x86-64's register to contain the address of the base of the page table) contain for any given process? Am I missing something?