I was re-reading Ian Lance Taylor's series of articles on Linkers [0], and one thing I didn't realise is that using dynamically linked libraries almost requires self-modifying code unless you want to resolve all function calls are start-time (which would make startup slower).

I'm still working my way through it so it's possible that I've misunderstood this section, though, and one question I haven't answered is how they get around the typical restriction on w+x pages.

[0] Particularly this one https://www.airs.com/blog/archives/41