[bpf-next v3 1/2] bpftool: Add auto_attach for bpf prog load|loadall

From: Wang Yufen
Date: Fri Sep 09 2022 - 01:42:14 EST


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>
---
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 | 76 ++++++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 74 insertions(+), 2 deletions(-)

diff --git a/tools/bpf/bpftool/prog.c b/tools/bpf/bpftool/prog.c
index c81362a..853a73e 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
+do_prog_attach_pin(struct bpf_program *prog, const char *path)
+{
+ struct bpf_link *link = NULL;
+ int err;
+
+ link = bpf_program__attach(prog);
+ err = libbpf_get_error(link);
+ 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)
+{
+ int len;
+
+ len = snprintf(buf, PATH_MAX, "%s/%s", path, name);
+ if (len < 0)
+ return -EINVAL;
+ else if (len >= PATH_MAX)
+ return -ENAMETOOLONG;
+
+ return 0;
+}
+
+static int
+do_obj_attach_pin_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 = do_prog_attach_pin(prog, buf);
+ if (err)
+ goto err_unpin_programs;
+ }
+
+ 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 = do_prog_attach_pin(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 = do_obj_attach_pin_programs(obj, pinfile);
+ else
+ err = bpf_object__pin_programs(obj, pinfile);
if (err) {
p_err("failed to pin all programs");
goto err_close_obj;
--
1.8.3.1