From: Alexei Starovoitov <alexei.starovoi...@gmail.com> Date: Mon, 20 Aug 2018 13:52:07 -0700
> I don't think copy-paste avoids the issue of uapi. > Anything used by BPF program is uapi. > The only exception is offsets of kernel internal structures > passed into bpf_probe_read(). > So we have several options: > 1. be honest and say 'struct flow_dissect_key*' is now uapi > 2. wrap all of them into 'struct bpf_flow_dissect_key*' and do rewrites > when/if 'struct flow_dissect_key*' changes > 3. wait for BTF to solve it for tracing use case and for this one two. ... > The idea is that kernel internal structs can be defined in bpf prog > and since they will be described precisely in BTF that comes with the prog > the kernel can validate that prog's BTF matches what kernel thinks it has. > imo that's the most flexible, but BTF for all of vmlinux won't be ready > tomorrow and looks like this patch set is ready to go, so I would go with 1 > or 2. I would definitely prefer #2 or #3. I personally would like to see us avoid preventing interesting optimizations of the flow key layout and/or accesses in the future.
