Exceptions in BPF

The problem is that you need to return all the way up the stack, and therefore you need to return some kind of "we're bailing out" status code to indicate the problem to the caller. But you probably already have return values at many of those call sites, so now you need to transform those return values in some way, probably into an option type or tagged union (or some equivalent). In principle that should be possible, but I don't know if BPF makes it straightforward or performant.