3 ms·

This is a thing; it's called shadow call stack. Both ARM and now Intel have extensions for it.

• vlovich123 3y ago
  But the shadow stack concept seems much dumber to me. Why write the address to the regular stack and the shadow stack and then compare? Why not only use the shadow stack and not put return addresses on the main stack at all.
  • BeeOnRope 3y ago
    ABI compatibility.
    • vlovich123 3y ago
      When you're compiling from scratch, especially when you're not working on a shared library, ABI compatability doesn't matter as much. Doesn't explain why there's no -fshadow-stack-only option to pass in.
      • BeeOnRope 3y ago
        > Doesn't explain why there's no -fshadow-stack-only option to pass in. I thought you were asking about the design of the hardware: it's designed that way because compatibility means that the vast majority of people want something backwards compatible. Very little is fully "compiled from scratch" when you consider for example that libc is in the set of things that must be recompiled.
  • th3typh00n 3y ago
    Because that would break compatibility. The way shadow stacks are implemented means they can be enabled in existing software without code changes. If one were to design a modern ISA from scratch it would make sense though.