2023-03-27 20:56 UTC+0300 ~ Eduard Zingerman <eddyz87@xxxxxxxxx> > On Mon, 2023-03-27 at 12:06 +0100, Quentin Monnet wrote: >> This set contains some improvements for bpftool's "visual" program dump >> option, which produces the control flow graph in a DOT format. The main >> objective is to add support for inline annotations on such graphs, so that >> we can have the C source code for the program showing up alongside the >> instructions, when available. The last commits also make it possible to >> display the line numbers or the bare opcodes in the graph, as supported by >> regular program dumps. >> >> v2: Replace fputc(..., stdout) with putchar(...) in dotlabel_puts(). > > Hi Quentin, > > It looks like currently there are no test cases for bpftool prog dump. > Borrowing an idea to mix bpf program with comments parsed by awk from > prog_tests/btf_dump.c it is possible to put together something like > below (although, would be much simpler as a bash script). Is it worth > the effort or dump format is too unstable? > > Thanks, > Eduard Correct, I don't think we have tests for that at the moment. But yes, I would love to get a test like this (and more bpftool tests in general, when I can find cycles). I don't mind a bash script, personally; your bpftool_cfg.c is mostly a succession of commands, and the other tests we have for bpftool are in bash or Python anyway (test_bpftool*). We could use bpftool to load the program (I suppose it's debatable whether it's good to use bpftool itself to set up a test for bpftool; on the other hand, it's heavily based on libbpf, so using libbpf directly doesn't seem to make that much of a difference). As for the stability of the output, generally the produced BPF bytecode is obviously subject to change, but for a program so simple as "return 0;" we should be mostly good. Just make sure you specify the ISA version when you compile the program, with < v3 we would load 64 bits instead of 32 in the first instruction. On bpftool's side, I don't expect the CFG output to change much, so no problem. Thanks a lot for your review, and for working on this test! I'll send a v3, probably sometime next week. Quentin
