Re: [PATCH bpf-next 2/5] bpftool: Fix bug for long instructions in program CFG dumps

[Stanislav Fomichev <sdf@google.com>]

On 03/24, Quentin Monnet wrote:
> When dumping the control flow graphs for programs using the 16-byte long
> load instruction, we need to skip the second part of this instruction
> when looking for the next instruction to process. Otherwise, we end up
> printing "BUG_ld_00" from the kernel disassembler in the CFG.

> Fixes: efcef17a6d65 ("tools: bpftool: generate .dot graph from CFG  
> information")
> Signed-off-by: Quentin Monnet <quentin@isovalent.com>
> ---
>   tools/bpf/bpftool/xlated_dumper.c | 7 +++++++
>   1 file changed, 7 insertions(+)

> diff --git a/tools/bpf/bpftool/xlated_dumper.c  
> b/tools/bpf/bpftool/xlated_dumper.c
> index 6fe3134ae45d..3daa05d9bbb7 100644
> --- a/tools/bpf/bpftool/xlated_dumper.c
> +++ b/tools/bpf/bpftool/xlated_dumper.c
> @@ -372,8 +372,15 @@ void dump_xlated_for_graph(struct dump_data *dd,  
> void *buf_start, void *buf_end,
>   	struct bpf_insn *insn_start = buf_start;
>   	struct bpf_insn *insn_end = buf_end;
>   	struct bpf_insn *cur = insn_start;
> +	bool double_insn = false;

>   	for (; cur <= insn_end; cur++) {
> +		if (double_insn) {
> +			double_insn = false;
> +			continue;
> +		}
> +		double_insn = cur->code == (BPF_LD | BPF_IMM | BPF_DW);
> +
>   		printf("% 4d: ", (int)(cur - insn_start + start_idx));
>   		print_bpf_insn(&cbs, cur, true);
>   		if (cur != insn_end)

Any reason not to do the following here instead?

	if (cur->code == (BPF_LD | BPF_IMM | BPF_DW))
		cur++;

> --
> 2.34.1