bpftool: Add autoattach for bpf prog load|loadall

Add autoattach optional to support one-step load-attach-pin_link.

For example,
   $ bpftool prog loadall test.o /sys/fs/bpf/test autoattach

   $ 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 autoattach optional can support tracepoints, k(ret)probes,
u(ret)probes.

Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: Wang Yufen <wangyufen@huawei.com>
Link: https://lore.kernel.org/r/1665736275-28143-2-git-send-email-wangyufen@huawei.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/tools/bpf/bpftool/prog.c b/tools/bpf/bpftool/prog.c
index c81362a..10ec29c 100644 (file)
--- a/tools/bpf/bpftool/prog.c
+++ b/tools/bpf/bpftool/prog.c
@@ -1453,6 +1453,67 @@ get_prog_type_by_name(const char *name, enum bpf_prog_type *prog_type,
        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);
+       if (!link) {
+               p_info("Program %s does not support autoattach, falling back to pinning",
+                      bpf_program__name(prog));
+               return bpf_obj_pin(bpf_program__fd(prog), path);
+       }
+
+       err = bpf_link__pin(link, path);
+       bpf_link__destroy(link);
+       return err;
+}
+
+static int pathname_concat(char *buf, size_t buf_sz, const char *path, const char *name)
+{
+       int len;
+
+       len = snprintf(buf, buf_sz, "%s/%s", path, name);
+       if (len < 0)
+               return -EINVAL;
+       if ((size_t)len >= buf_sz)
+               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(buf, sizeof(buf), path, bpf_program__name(prog));
+               if (err)
+                       goto err_unpin_programs;
+
+               err = auto_attach_program(prog, buf);
+               if (err)
+                       goto err_unpin_programs;
+       }
+
+       return 0;
+
+err_unpin_programs:
+       while ((prog = bpf_object__prev_program(obj, prog))) {
+               if (pathname_concat(buf, sizeof(buf), path, bpf_program__name(prog)))
+                       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 +1525,7 @@ 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 +1645,9 @@ 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, "autoattach")) {
+                       auto_attach = true;
+                       NEXT_ARG();
                } else {
                        p_err("expected no more arguments, 'type', 'map' or 'dev', got: '%s'?",
                              *argv);
@@ -1692,14 +1757,20 @@ 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 +2409,7 @@ static int do_help(int argc, char **argv)
                "                         [type TYPE] [dev NAME] \\\n"
                "                         [map { idx IDX | name NAME } MAP]\\\n"
                "                         [pinmaps MAP_DIR]\n"
+               "                         [autoattach]\n"
                "       %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"