libbpf: Export bpf_program__attach_kprobe_opts function

Export bpf_program__attach_kprobe_opts as a public API.

Rename bpf_program_attach_kprobe_opts to bpf_kprobe_opts and turn it into OPTS
struct.

Suggested-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Reviewed-by: Alan Maguire <alan.maguire@oracle.com>
Tested-by: Alan Maguire <alan.maguire@oracle.com>
Link: https://lore.kernel.org/bpf/20210721215810.889975-4-jolsa@kernel.org

tools/lib/bpf/libbpf.c

@@ -10366,25 +10366,28 @@ static int perf_event_open_probe(bool uprobe, bool retprobe, const char *name,
 	return pfd;
 }
 
-struct bpf_program_attach_kprobe_opts {
-	bool retprobe;
-	unsigned long offset;
-};
-
-static struct bpf_link*
+struct bpf_link *
 bpf_program__attach_kprobe_opts(struct bpf_program *prog,
 				const char *func_name,
-				struct bpf_program_attach_kprobe_opts *opts)
+				struct bpf_kprobe_opts *opts)
 {
 	char errmsg[STRERR_BUFSIZE];
 	struct bpf_link *link;
+	unsigned long offset;
+	bool retprobe;
 	int pfd, err;
 
-	pfd = perf_event_open_probe(false /* uprobe */, opts->retprobe, func_name,
-				    opts->offset, -1 /* pid */);
+	if (!OPTS_VALID(opts, bpf_kprobe_opts))
+		return libbpf_err_ptr(-EINVAL);
+
+	retprobe = OPTS_GET(opts, retprobe, false);
+	offset = OPTS_GET(opts, offset, 0);
+
+	pfd = perf_event_open_probe(false /* uprobe */, retprobe, func_name,
+				    offset, -1 /* pid */);
 	if (pfd < 0) {
 		pr_warn("prog '%s': failed to create %s '%s' perf event: %s\n",
-			prog->name, opts->retprobe ? "kretprobe" : "kprobe", func_name,
+			prog->name, retprobe ? "kretprobe" : "kprobe", func_name,
 			libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));
 		return libbpf_err_ptr(pfd);
 	}
@@ -10393,7 +10396,7 @@ bpf_program__attach_kprobe_opts(struct bpf_program *prog,
 	if (err) {
 		close(pfd);
 		pr_warn("prog '%s': failed to attach to %s '%s': %s\n",
-			prog->name, opts->retprobe ? "kretprobe" : "kprobe", func_name,
+			prog->name, retprobe ? "kretprobe" : "kprobe", func_name,
 			libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
 		return libbpf_err_ptr(err);
 	}
@@ -10404,17 +10407,17 @@ struct bpf_link *bpf_program__attach_kprobe(struct bpf_program *prog,
 					    bool retprobe,
 					    const char *func_name)
 {
-	struct bpf_program_attach_kprobe_opts opts = {
+	DECLARE_LIBBPF_OPTS(bpf_kprobe_opts, opts,
 		.retprobe = retprobe,
-	};
+	);
 
 	return bpf_program__attach_kprobe_opts(prog, func_name, &opts);
 }
 
 static struct bpf_link *attach_kprobe(const struct bpf_sec_def *sec,
 				      struct bpf_program *prog)
 {
-	struct bpf_program_attach_kprobe_opts opts;
+	DECLARE_LIBBPF_OPTS(bpf_kprobe_opts, opts);
 	unsigned long offset = 0;
 	struct bpf_link *link;
 	const char *func_name;

tools/lib/bpf/libbpf.h

@@ -104,6 +104,17 @@ struct bpf_object_open_opts {
 };
 #define bpf_object_open_opts__last_field btf_custom_path
 
+struct bpf_kprobe_opts {
+	/* size of this struct, for forward/backward compatiblity */
+	size_t sz;
+	/* function's offset to install kprobe to */
+	unsigned long offset;
+	/* kprobe is return probe */
+	bool retprobe;
+	size_t :0;
+};
+#define bpf_kprobe_opts__last_field retprobe
+
 LIBBPF_API struct bpf_object *bpf_object__open(const char *path);
 LIBBPF_API struct bpf_object *
 bpf_object__open_file(const char *path, const struct bpf_object_open_opts *opts);
@@ -250,6 +261,10 @@ LIBBPF_API struct bpf_link *
 bpf_program__attach_kprobe(struct bpf_program *prog, bool retprobe,
 			   const char *func_name);
 LIBBPF_API struct bpf_link *
+bpf_program__attach_kprobe_opts(struct bpf_program *prog,
+                                const char *func_name,
+                                struct bpf_kprobe_opts *opts);
+LIBBPF_API struct bpf_link *
 bpf_program__attach_uprobe(struct bpf_program *prog, bool retprobe,
 			   pid_t pid, const char *binary_path,
 			   size_t func_offset);

tools/lib/bpf/libbpf.map

@@ -372,6 +372,7 @@ LIBBPF_0.5.0 {
 	global:
 		bpf_map__initial_value;
 		bpf_map_lookup_and_delete_elem_flags;
+		bpf_program__attach_kprobe_opts;
 		bpf_object__gen_loader;
 		btf_dump__dump_type_data;
 		libbpf_set_strict_mode;