在 2022/9/24 5:29, Andrii Nakryiko 写道:
On Wed, Sep 21, 2022 at 12:40 AM Wang Yufen <wangyufen@xxxxxxxxxx> wrote:Add auto_attach optional to support one-step load-attach-pin_link. For example, $ bpftool prog loadall test.o /sys/fs/bpf/test auto_attach $ bpftool link 26: tracing name test1 tag f0da7d0058c00236 gpl loaded_at 2022-09-09T21:39:49+0800 uid 0 xlated 88B jited 55B memlock 4096B map_ids 3 btf_id 55 28: kprobe name test3 tag 002ef1bef0723833 gpl loaded_at 2022-09-09T21:39:49+0800 uid 0 xlated 88B jited 56B memlock 4096B map_ids 3 btf_id 55 57: tracepoint name oncpu tag 7aa55dfbdcb78941 gpl loaded_at 2022-09-09T21:41:32+0800 uid 0 xlated 456B jited 265B memlock 4096B map_ids 17,13,14,15 btf_id 82 $ bpftool link 1: tracing prog 26 prog_type tracing attach_type trace_fentry 3: perf_event prog 28 10: perf_event prog 57 The auto_attach optional can support tracepoints, k(ret)probes, u(ret)probes. Signed-off-by: Wei Yongjun <weiyongjun1@xxxxxxxxxx> Signed-off-by: Wang Yufen <wangyufen@xxxxxxxxxx> Reviewed-by: Quentin Monnet <quentin@xxxxxxxxxxxxx> --- v4 -> v5: some formatting nits of doc v3 -> v4: rename functions, update doc, bash and do_help() v2 -> v3: switch to extend prog load command instead of extend perf v2: https://patchwork.kernel.org/project/netdevbpf/patch/20220824033837.458197-1-weiyongjun1@xxxxxxxxxx/ v1: https://patchwork.kernel.org/project/netdevbpf/patch/20220816151725.153343-1-weiyongjun1@xxxxxxxxxx/ tools/bpf/bpftool/prog.c | 77 ++++++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 75 insertions(+), 2 deletions(-) diff --git a/tools/bpf/bpftool/prog.c b/tools/bpf/bpftool/prog.c index c81362a..aea0b57 100644 --- a/tools/bpf/bpftool/prog.c +++ b/tools/bpf/bpftool/prog.c @@ -1453,6 +1453,68 @@ static int do_run(int argc, char **argv) return ret; } +static int +auto_attach_program(struct bpf_program *prog, const char *path) +{ + struct bpf_link *link; + int err; + + link = bpf_program__attach(prog); + err = libbpf_get_error(link);nit: bpftool uses libbpf 1.0, so no need to use libbpf_get_error() anymore, you can just check link for NULL and then look at errno
Thanks, will change in v6
but I wanted to check on desired behavior here. BPF skeleton will skip programs that can't be auto-attached because they are of the type that can't be declaratively specified to be auto-attachable. For such programs bpf_program__attach() will return -EOPNOTSUPP and libbpf's skeleton_attach API will silently skip them. Should bpftool be stricter about such programs here or should it follow BPF skeleton approach?
will change auto_attach_programs() to follow BPF skeleton approach in v6
+ if (err) + return err; + + err = bpf_link__pin(link, path); + if (err) { + bpf_link__destroy(link); + return err; + } + return 0; +} + +static int pathname_concat(const char *path, const char *name, char *buf)you added buffer size in libbpf version of this function, maybe match the same signature (I also moved buf and buf_sz to be first two args).+{ + int len; + + len = snprintf(buf, PATH_MAX, "%s/%s", path, name); + if (len < 0) + return -EINVAL; + if (len >= PATH_MAX) + return -ENAMETOOLONG; + + return 0; +} + +static int +auto_attach_programs(struct bpf_object *obj, const char *path) +{ + struct bpf_program *prog; + char buf[PATH_MAX]; + int err; + + bpf_object__for_each_program(prog, obj) { + err = pathname_concat(path, bpf_program__name(prog), buf); + if (err) + goto err_unpin_programs; + + err = auto_attach_program(prog, buf); + if (err) + goto err_unpin_programs; + } +would it be safer to first make sure that all programs are auto-attached and then pin links? also note that not all bpf_links returned by libbpf are actual links in kernel (e.g., kprobe/tp bpf_link on older kernels).
will silently skip the unsupport programs as BPF skeleton approach
+ return 0; + +err_unpin_programs: + while ((prog = bpf_object__prev_program(obj, prog))) { + if (pathname_concat(path, bpf_program__name(prog), buf)) + continue; + + bpf_program__unpin(prog, buf); + } + + return err; +} + static int load_with_options(int argc, char **argv, bool first_prog_only) { enum bpf_prog_type common_prog_type = BPF_PROG_TYPE_UNSPEC; @@ -1464,6 +1526,7 @@ static int load_with_options(int argc, char **argv, bool first_prog_only) struct bpf_program *prog = NULL, *pos; unsigned int old_map_fds = 0; const char *pinmaps = NULL; + bool auto_attach = false; struct bpf_object *obj; struct bpf_map *map; const char *pinfile; @@ -1583,6 +1646,9 @@ static int load_with_options(int argc, char **argv, bool first_prog_only) goto err_free_reuse_maps; pinmaps = GET_ARG(); + } else if (is_prefix(*argv, "auto_attach")) { + auto_attach = true; + NEXT_ARG(); } else { p_err("expected no more arguments, 'type', 'map' or 'dev', got: '%s'?", *argv); @@ -1692,14 +1758,20 @@ static int load_with_options(int argc, char **argv, bool first_prog_only) goto err_close_obj; } - err = bpf_obj_pin(bpf_program__fd(prog), pinfile); + if (auto_attach) + err = auto_attach_program(prog, pinfile); + else + err = bpf_obj_pin(bpf_program__fd(prog), pinfile); if (err) { p_err("failed to pin program %s", bpf_program__section_name(prog)); goto err_close_obj; } } else { - err = bpf_object__pin_programs(obj, pinfile); + if (auto_attach) + err = auto_attach_programs(obj, pinfile); + else + err = bpf_object__pin_programs(obj, pinfile); if (err) { p_err("failed to pin all programs"); goto err_close_obj; @@ -2338,6 +2410,7 @@ static int do_help(int argc, char **argv) " [type TYPE] [dev NAME] \\\n" " [map { idx IDX | name NAME } MAP]\\\n" " [pinmaps MAP_DIR]\n" + " [auto_attach]\n"looking at "pinmaps" seems like "autoattach" would be more consistent naming? Or just "attach"?
will change to "autoattach" in v6
" %1$s %2$s attach PROG ATTACH_TYPE [MAP]\n" " %1$s %2$s detach PROG ATTACH_TYPE [MAP]\n" " %1$s %2$s run PROG \\\n" -- 1.8.3.1
