On Fri, 17 Sep 2021 11:43:07 -0700 Alexei Starovoitov wrote: > > If bpf_xdp_load_bytes() / bpf_xdp_store_bytes() works for most we > > can start with that. In all honesty I don't know what the exact > > use cases for looking at data are, either. I'm primarily worried > > about exposing the kernel internals too early. > > I don't mind the xdp equivalent of skb_load_bytes, > but skb_header_pointer() idea is superior. > When we did xdp with data/data_end there was no refine_retval_range > concept in the verifier (iirc or we just missed that opportunity). > We'd need something more advanced: a pointer with valid range > refined by input argument 'len' or NULL. > The verifier doesn't have such thing yet, but it fits as a combination of > value_or_null plus refine_retval_range. > The bpf_xdp_header_pointer() and bpf_skb_header_pointer() > would probably simplify bpf programs as well. > There would be no need to deal with data/data_end. What are your thoughts on inlining? Can we inline the common case of the header being in the "head"? Otherwise data/end comparisons would be faster.
