This patchset implements the basics of dynamic pointers in bpf. A dynamic pointer (struct bpf_dynptr) is a pointer that stores extra metadata alongside the address it points to. This abstraction is useful in bpf, given that every memory access in a bpf program must be safe. The verifier and bpf helper functions can use the metadata to enforce safety guarantees for things such as dynamically sized strings and kernel heap allocations.
