Lorenz Bauer <lmb@xxxxxxxxxxxxxx> writes: > On Thu, 16 Sept 2021 at 18:47, Jakub Kicinski <kuba@xxxxxxxxxx> wrote: >> >> Won't applications end up building something like skb_header_pointer() >> based on bpf_xdp_adjust_data(), anyway? In which case why don't we >> provide them what they need? >> >> say: >> >> void *xdp_mb_pointer(struct xdp_buff *xdp_md, u32 flags, >> u32 offset, u32 len, void *stack_buf) >> >> flags and offset can be squashed into one u64 as needed. Helper returns >> pointer to packet data, either real one or stack_buf. Verifier has to >> be taught that the return value is NULL or a pointer which is safe with >> offsets up to @len. >> >> If the reason for access is write we'd also need: >> >> void *xdp_mb_pointer_flush(struct xdp_buff *xdp_md, u32 flags, >> u32 offset, u32 len, void *stack_buf) > > Yes! This would be so much better than bpf_skb_load/store_bytes(), > especially if we can use it for both XDP and skb contexts as stated > elsewhere in this thread. Alright. Let's see if we can go this route, then :) -Toke
