On Mon, 2024-01-08 at 16:45 -0800, Andrii Nakryiko wrote: [...] > > @@ -14713,6 +14714,13 @@ static bool try_match_pkt_pointers(const struct bpf_insn *insn, > > find_good_pkt_pointers(other_branch, dst_reg, dst_reg->type, opcode == BPF_JLT); > > mark_pkt_end(this_branch, dst_regno, opcode == BPF_JLE); > > break; > > + case BPF_JEQ: > > + case BPF_JNE: > > + /* pkt_data ==/!= pkt_end, pkt_meta ==/!= pkt_data */ > > + eq_branch = opcode == BPF_JEQ ? other_branch : this_branch; > > + find_good_pkt_pointers(eq_branch, dst_reg, dst_reg->type, true); > > + mark_pkt_end(eq_branch, dst_regno, false); > > hm... if pkt_data != pkt_end in this_branch, can we really infer > whether reg->range is BEYOND_PKT_END or AT_PKT_END? What if it's > IN_FRONT_OF_PKT_END? pkt_data != pkt_end in this_branch means that there is an instruction: ... if pkt_data == pkt_end goto <other_branch> ... <this_branch> ... the 'eq_branch' would be set to 'other_branch' and AT_PKT_END would be set for dst register in 'other_branch'. What's wrong with this? Or did you mean something else?
