Yeah, self modifying has become harder. As far as I know the most robust solution to that now is like what Julia does, where it can compile new generations of any module to update call targets, for example. At worst, when seccomp disallows flipping a writable page to executable at runtime, you can always compile into a file then dlopen the file. In other words, it can take many more contortions now than it used to, but it’s still possible.