Shared libraries and PLT using GCC toolchain

Hi all, I am trying to understand how shared libraries and PLT works. As per my current understanding linking a shared library should output code that calls a function (function from the shared library...
maximum level of functions than can be called within

function1 calling function2, function2 calling function3, function3 calling function4 and so on. Maximum stage depends upon Stack Size, right? How to identify Stack Size and if required how to change...
Calling None-Secure method directly from Secure world

Hi: If CPU is in secure state, and calling the none-secure world method. Dose this allowed or it will generat a security fault