[RFC PATCH v2 20/26] perf bpf: Accept uBPF programs

[He Kuang]

From: Wang Nan <wangnan0@xxxxxxxxxx>

This patch allows user passing a uBPF function through bpf file with
section name leading with 'UBPF;'. For example:

 #define SEC(NAME) __attribute__((section(NAME), used))
 SEC("UBPF;perf_record_exit")
 void record_exit(int *samples)
 {
    char fmt[] = "Hello! receive %d samples\n";
    ubpf_printf(fmt, *samples);
 }

Signed-off-by: Wang Nan <wangnan0@xxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Alexei Starovoitov <ast@xxxxxxxxxx>
Cc: Brendan Gregg <brendan.d.gregg@xxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Li Zefan <lizefan@xxxxxxxxxx>
Signed-off-by: He Kuang <hekuang@xxxxxxxxxx>
---
 tools/perf/util/bpf-loader.c | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/tools/perf/util/bpf-loader.c b/tools/perf/util/bpf-loader.c
index 2ac73e3..288b941 100644
--- a/tools/perf/util/bpf-loader.c
+++ b/tools/perf/util/bpf-loader.c
@@ -305,6 +305,19 @@ config_bpf_program(struct bpf_program *prog)
 		return PTR_ERR(config_str);
 	}
 
+	if (strncmp(config_str, "UBPF;", 5) == 0) {
+		pr_debug("bpf: load a UBPF program %s\n", config_str);
+		err = bpf_program__set_ubpf(prog);
+		if (err) {
+			char errbuf[BUFSIZ];
+
+			libbpf_strerror(err, errbuf, sizeof(errbuf));
+			pr_warning("Set %s to ubpf failed: %s\n", config_str, errbuf);
+			return err;
+		}
+		return 0;
+	}
+
 	priv = calloc(sizeof(*priv), 1);
 	if (!priv) {
 		pr_debug("bpf: failed to alloc priv\n");
@@ -604,6 +617,9 @@ int bpf__probe(struct bpf_object *obj)
 		if (err)
 			goto out;
 
+		if (bpf_program__is_ubpf(prog))
+			continue;
+
 		priv = bpf_program__priv(prog);
 		if (IS_ERR(priv) || !priv) {
 			err = PTR_ERR(priv);
@@ -649,6 +665,9 @@ int bpf__unprobe(struct bpf_object *obj)
 		struct bpf_prog_priv *priv = bpf_program__priv(prog);
 		int i;
 
+		if (bpf_program__is_ubpf(prog))
+			continue;
+
 		if (IS_ERR(priv) || !priv)
 			continue;
 
@@ -705,6 +724,9 @@ int bpf__foreach_tev(struct bpf_object *obj,
 		struct perf_probe_event *pev;
 		int i, fd;
 
+		if (bpf_program__is_ubpf(prog))
+			continue;
+
 		if (IS_ERR(priv) || !priv) {
 			pr_debug("bpf: failed to get private field\n");
 			return -BPF_LOADER_ERRNO__INTERNAL;
-- 
1.8.5.2