libbpf: Add support for u[ret]probe.multi[.s] program sections

Adding support for several uprobe_multi program sections
to allow auto attach of multi_uprobe programs.

Acked-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20230809083440.3209381-16-jolsa@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Author: olsajiri

tools/lib/bpf/libbpf.c

@@ -8701,6 +8701,7 @@ static int attach_tp(const struct bpf_program *prog, long cookie, struct bpf_lin
 static int attach_raw_tp(const struct bpf_program *prog, long cookie, struct bpf_link **link);
 static int attach_trace(const struct bpf_program *prog, long cookie, struct bpf_link **link);
 static int attach_kprobe_multi(const struct bpf_program *prog, long cookie, struct bpf_link **link);
+static int attach_uprobe_multi(const struct bpf_program *prog, long cookie, struct bpf_link **link);
 static int attach_lsm(const struct bpf_program *prog, long cookie, struct bpf_link **link);
 static int attach_iter(const struct bpf_program *prog, long cookie, struct bpf_link **link);
 
@@ -8716,6 +8717,10 @@ static const struct bpf_sec_def section_defs[] = {
 	SEC_DEF("uretprobe.s+",		KPROBE, 0, SEC_SLEEPABLE, attach_uprobe),
 	SEC_DEF("kprobe.multi+",	KPROBE,	BPF_TRACE_KPROBE_MULTI, SEC_NONE, attach_kprobe_multi),
 	SEC_DEF("kretprobe.multi+",	KPROBE,	BPF_TRACE_KPROBE_MULTI, SEC_NONE, attach_kprobe_multi),
+	SEC_DEF("uprobe.multi+",	KPROBE,	BPF_TRACE_UPROBE_MULTI, SEC_NONE, attach_uprobe_multi),
+	SEC_DEF("uretprobe.multi+",	KPROBE,	BPF_TRACE_UPROBE_MULTI, SEC_NONE, attach_uprobe_multi),
+	SEC_DEF("uprobe.multi.s+",	KPROBE,	BPF_TRACE_UPROBE_MULTI, SEC_SLEEPABLE, attach_uprobe_multi),
+	SEC_DEF("uretprobe.multi.s+",	KPROBE,	BPF_TRACE_UPROBE_MULTI, SEC_SLEEPABLE, attach_uprobe_multi),
 	SEC_DEF("ksyscall+",		KPROBE,	0, SEC_NONE, attach_ksyscall),
 	SEC_DEF("kretsyscall+",		KPROBE, 0, SEC_NONE, attach_ksyscall),
 	SEC_DEF("usdt+",		KPROBE,	0, SEC_NONE, attach_usdt),
@@ -10922,6 +10927,37 @@ static int attach_kprobe_multi(const struct bpf_program *prog, long cookie, stru
 	return libbpf_get_error(*link);
 }
 
+static int attach_uprobe_multi(const struct bpf_program *prog, long cookie, struct bpf_link **link)
+{
+	char *probe_type = NULL, *binary_path = NULL, *func_name = NULL;
+	LIBBPF_OPTS(bpf_uprobe_multi_opts, opts);
+	int n, ret = -EINVAL;
+
+	*link = NULL;
+
+	n = sscanf(prog->sec_name, "%m[^/]/%m[^:]:%ms",
+		   &probe_type, &binary_path, &func_name);
+	switch (n) {
+	case 1:
+		/* handle SEC("u[ret]probe") - format is valid, but auto-attach is impossible. */
+		ret = 0;
+		break;
+	case 3:
+		opts.retprobe = strcmp(probe_type, "uretprobe.multi") == 0;
+		*link = bpf_program__attach_uprobe_multi(prog, -1, binary_path, func_name, &opts);
+		ret = libbpf_get_error(*link);
+		break;
+	default:
+		pr_warn("prog '%s': invalid format of section definition '%s'\n", prog->name,
+			prog->sec_name);
+		break;
+	}
+	free(probe_type);
+	free(binary_path);
+	free(func_name);
+	return ret;
+}
+
 static void gen_uprobe_legacy_event_name(char *buf, size_t buf_sz,
 					 const char *binary_path, uint64_t offset)
 {