You want us to change the type "bin_t" into what? I assumed that you want to relabel the type and I tried relabelling #chcon -t xdm_exec_t /usr/sbin/gdm3
but it didn't work. Still stuck with a black screen. I had to disable the selinux at boot to login to X. Now I am at #ls -Z /usr/sbin/gdm3 system_u:object_r:xdm_exec_t:s0 /usr/sbin/gdm3