Background information
We are going to interfere with and control the CPU directly. This is not very portable since there are many kinds of CPUs out there. While the overall implementation will be the same, there is a small but important part of the implementation that will be very specific to the CPU architecture we’re programming for. Another aspect that limits the portability of our code is that operating systems have different ABIs that we need to adhere to, and those same pieces of code will have to change based on the different ABIs. Let’s explain exactly what we mean here before we go further so we know we’re on the same page.
Instruction sets, hardware architectures, and ABIs
Okay, before we start, we need to know the differences between an application binary interface (ABI), a CPU architecture, and an instruction set architecture (ISA). We need this to write our own stack and make the CPU jump over to it. Fortunately, while this might sound complex...
