this is a simple program to illustrate how page tables work in x86_64 linux.

the best explanation i've found for x86_64 page tables is
https://os.phil-opp.com/page-tables/ 

the pagetables program uses CR3 (the register that points to the top level
page table to resolve a virtual memory address (one of the program's
functions.

unfortunately, (unless you are security concious then you would be super
happy!) so we need a kernel module to allow us to access CR3 and the
physical memory. when you build and insmod cr3.ko in the kernel-module
directory you will get /proc/cr3 and /proc/page_reader that will give
you access to CR3 and physical pages.

pagetable.c will use those two files to resolve virtual addresses.
/proc/page_reader doesn't totally compromise the OS, so you will need
to run pagetable as root.

here is a sample execution after your git clone:

$ make 
$ cd kernel-module
$ make
$ sudo insmod ./cr3.ko
$ cd ..
$ sudo ./pagetables
...
lots of interesting data
...