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cilium#339 changed how pwru tracks skb from using &skb to skb->head for xdp tracing. We found it causing problems such as: 1. An skb can have multiple different skb->head values during its lifetime, especically after (e.g. IPsec) encryption. Pwru now is likely to lose track of skb after encryption. 2. Some subtle issues like cilium#401. This is because some other tracking mechanism relies on &skb. This commit brings back tracking &skb instead of skb->head. As for XDP tracing, I'll introduce a new solution in the following patches. Signed-off-by: gray <gray.liang@isovalent.com>
This commit records xdp->data_hard_start at fexit/xdp. The skb built from xdp_md will have the same value of skb->head. Signed-off-by: gray <gray.liang@isovalent.com>
Signed-off-by: gray <gray.liang@isovalent.com>
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Requesting an additional review from @brb since I'm not that familiar with the BPF bits of pwru. |
tklauser
approved these changes
Aug 6, 2024
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This PR uses &skb to track skb instead of skb->head to prevent several issues. XDP tracing is also taken care of by introducing a new bpf map
xdp_dhs_skb_heads.