How can i access the page table of a process from kernel using a custom syscall?

I am using Ubuntu 16.04, kernel: 4.17.4 I want to access the page table of a process. The idea is, inside a c code I will call a custom Syscall and the syscall will be able to access the page table of the process. How do I design the system call? I'd appreciate any example or related reading materials. My job is to modify some page table entries (changing some virtual address to physical address mapping) of the page table for a project which I want to do using the syscall.