This patchset adds the base infrastructure for modular BPF verifier. The motivation remains unchanged from the LSFMMBPF25 proposal [0]. However, the design has diverged. Rather than immediately going for the facade described in [0], we instead make a stop first at the continously exported copies of the verifier in an out-of-tree repository, with a separate copy for each kernel release. Each copy will receive as many verifier backports as possible within the "boundary" of the modular portions. For example, a patch that changes the verifier at the same time as one of the kernel symbols it depends on cannot be applied, as at runtime only the verifier portion can be updated. However, a patch that only changes verifier.c can be applied, as it's within the boundary. Rough analysis of past data shows that most verifier changes fall within the latter category. The jupyter notebook for this can be found here [1].
