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

[He Kuang]

From: Wang Nan <wangn...@huawei.com>

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 <wangn...@huawei.com>
Cc: Arnaldo Carvalho de Melo <a...@redhat.com>
Cc: Alexei Starovoitov <a...@kernel.org>
Cc: Brendan Gregg <brendan.d.gr...@gmail.com>
Cc: Jiri Olsa <jo...@kernel.org>
Cc: Li Zefan <lize...@huawei.com>
Signed-off-by: He Kuang <heku...@huawei.com>
---
 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