Add a cookie field to the attributes of bpf_link_create().
Add bpf_program__attach_trace_opts() to attach a cookie to a link.
Signed-off-by: Kui-Feng Lee <kuifeng@xxxxxx>
---
tools/lib/bpf/bpf.c | 7 +++++++
tools/lib/bpf/bpf.h | 3 +++
tools/lib/bpf/libbpf.c | 38 ++++++++++++++++++++++++++++++++++++++
tools/lib/bpf/libbpf.h | 12 ++++++++++++
tools/lib/bpf/libbpf.map | 1 +
5 files changed, 61 insertions(+)
diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
index cf27251adb92..1a96fd9b1da9 100644
--- a/tools/lib/bpf/bpf.c
+++ b/tools/lib/bpf/bpf.c
@@ -863,6 +863,13 @@ int bpf_link_create(int prog_fd, int target_fd,
if (!OPTS_ZEROED(opts, kprobe_multi))
return libbpf_err(-EINVAL);
break;
+ case BPF_TRACE_FENTRY:
+ case BPF_TRACE_FEXIT:
+ case BPF_MODIFY_RETURN:
+ attr.link_create.tracing.cookie = OPTS_GET(opts, tracing.cookie, 0);
+ if (!OPTS_ZEROED(opts, tracing))
+ return libbpf_err(-EINVAL);
+ break;
default:
if (!OPTS_ZEROED(opts, flags))
return libbpf_err(-EINVAL);
diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h
index f4b4afb6d4ba..2f9099c945bc 100644
--- a/tools/lib/bpf/bpf.h
+++ b/tools/lib/bpf/bpf.h
@@ -410,6 +410,9 @@ struct bpf_link_create_opts {
__u32 iter_info_len;
__u32 target_btf_id;
union {
+ struct {
+ __u64 cookie;
+ } tracing;
struct {
__u64 bpf_cookie;
} perf_event;
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index bf4f7ac54ebf..7e18fe94bfe5 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -11262,6 +11262,44 @@ struct bpf_link *bpf_program__attach_trace(const struct bpf_program *prog)
return bpf_program__attach_btf_id(prog);
}
+struct bpf_link *bpf_program__attach_trace_opts(const struct bpf_program *prog,
+ const struct bpf_trace_opts *opts)
+{
+ char errmsg[STRERR_BUFSIZE];
+ struct bpf_link *link;
+ int prog_fd, pfd;
+ LIBBPF_OPTS(bpf_link_create_opts, link_opts);
+
+ /* Fallback for cookie is 0. Old kernels don't create
+ * fentry/fexit links through LINK_CREATE.
+ */
+ if (OPTS_GET(opts, cookie, 0))
+ return bpf_program__attach_trace(prog);
+
+ prog_fd = bpf_program__fd(prog);
+ if (prog_fd < 0) {
+ pr_warn("prog '%s': can't attach before loaded\n", prog->name);
+ return libbpf_err_ptr(-EINVAL);
+ }
+
+ link = calloc(1, sizeof(*link));
+ if (!link)
+ return libbpf_err_ptr(-ENOMEM);
+ link->detach = &bpf_link__detach_fd;
+
+ link_opts.tracing.cookie = OPTS_GET(opts, cookie, 0);
+ pfd = bpf_link_create(prog_fd, 0, prog->expected_attach_type, &link_opts);
+ if (pfd < 0) {
+ pfd = -errno;
+ free(link);
+ pr_warn("prog '%s': failed to attach: %s\n",
+ prog->name, libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));
+ return libbpf_err_ptr(pfd);
+ }
+ link->fd = pfd;
+ return (struct bpf_link *)link;
+}
+
struct bpf_link *bpf_program__attach_lsm(const struct bpf_program *prog)
{
return bpf_program__attach_btf_id(prog);
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index 63d66f1adf1a..213de69bc173 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -563,8 +563,20 @@ bpf_program__attach_tracepoint_opts(const struct bpf_program *prog,
LIBBPF_API struct bpf_link *
bpf_program__attach_raw_tracepoint(const struct bpf_program *prog,
const char *tp_name);
+
+struct bpf_trace_opts {
+ /* size of this struct, for forward/backward compatibility */
+ size_t sz;
+ /* custom user-provided value fetchable through bpf_get_attach_cookie() */
+ __u64 cookie;
+};
+#define bpf_trace_opts__last_field cookie
+
LIBBPF_API struct bpf_link *
bpf_program__attach_trace(const struct bpf_program *prog);
+LIBBPF_API struct bpf_link *
+bpf_program__attach_trace_opts(const struct bpf_program *prog, const struct bpf_trace_opts *opts);
+
LIBBPF_API struct bpf_link *
bpf_program__attach_lsm(const struct bpf_program *prog);
LIBBPF_API struct bpf_link *
diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index 82f6d62176dd..245a0e8677c9 100644
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -444,6 +444,7 @@ LIBBPF_0.8.0 {
global:
bpf_object__destroy_subskeleton;
bpf_object__open_subskeleton;
+ bpf_program__attach_trace_opts;
bpf_program__attach_usdt;
libbpf_register_prog_handler;
libbpf_unregister_prog_handler;
--
2.30.2
