bpftool: Fix bug for long instructions in program CFG dumps

[ Upstream commit 67cf52c ]

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: efcef17 ("tools: bpftool: generate .dot graph from CFG information")
Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/r/20230405132120.59886-3-quentin@isovalent.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

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)