[PATCH v4 bpf-next 6/9] libbpf: add raw tracepoint attach API

[Andrii Nakryiko]

Add a wrapper utilizing bpf_link "infrastructure" to allow attaching BPF
programs to raw tracepoints.

Signed-off-by: Andrii Nakryiko <andr...@fb.com>
Acked-by: Song Liu <songliubrav...@fb.com>
---
 tools/lib/bpf/libbpf.c   | 37 +++++++++++++++++++++++++++++++++++++
 tools/lib/bpf/libbpf.h   |  3 +++
 tools/lib/bpf/libbpf.map |  1 +
 3 files changed, 41 insertions(+)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 8ad4f915df38..f8c7a7ecb35e 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -4263,6 +4263,43 @@ struct bpf_link *bpf_program__attach_tracepoint(struct 
bpf_program *prog,
        return link;
 }
 
+static int bpf_link__destroy_fd(struct bpf_link *link)
+{
+       struct bpf_link_fd *l = (void *)link;
+
+       return close(l->fd);
+}
+
+struct bpf_link *bpf_program__attach_raw_tracepoint(struct bpf_program *prog,
+                                                   const char *tp_name)
+{
+       char errmsg[STRERR_BUFSIZE];
+       struct bpf_link_fd *link;
+       int prog_fd, pfd;
+
+       prog_fd = bpf_program__fd(prog);
+       if (prog_fd < 0) {
+               pr_warning("program '%s': can't attach before loaded\n",
+                          bpf_program__title(prog, false));
+               return ERR_PTR(-EINVAL);
+       }
+
+       link = malloc(sizeof(*link));
+       link->link.destroy = &bpf_link__destroy_fd;
+
+       pfd = bpf_raw_tracepoint_open(tp_name, prog_fd);
+       if (pfd < 0) {
+               pfd = -errno;
+               free(link);
+               pr_warning("program '%s': failed to attach to raw tracepoint 
'%s': %s\n",
+                          bpf_program__title(prog, false), tp_name,
+                          libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));
+               return ERR_PTR(pfd);
+       }
+       link->fd = pfd;
+       return (struct bpf_link *)link;
+}
+
 enum bpf_perf_event_ret
 bpf_perf_event_read_simple(void *mmap_mem, size_t mmap_size, size_t page_size,
                           void **copy_mem, size_t *copy_size,
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index 60611f4b4e1d..f55933784f95 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -182,6 +182,9 @@ LIBBPF_API struct bpf_link *
 bpf_program__attach_tracepoint(struct bpf_program *prog,
                               const char *tp_category,
                               const char *tp_name);
+LIBBPF_API struct bpf_link *
+bpf_program__attach_raw_tracepoint(struct bpf_program *prog,
+                                  const char *tp_name);
 
 struct bpf_insn;
 
diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index 3c618b75ef65..e6b7d4edbc93 100644
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -171,6 +171,7 @@ LIBBPF_0.0.4 {
                bpf_object__load_xattr;
                bpf_program__attach_kprobe;
                bpf_program__attach_perf_event;
+               bpf_program__attach_raw_tracepoint;
                bpf_program__attach_tracepoint;
                bpf_program__attach_uprobe;
                btf_dump__dump_type;
-- 
2.17.1