[PATCH 04/13] perf tools: Allow BPF program attach to modules

[Wang Nan <wangnan0@huawei.com>]

By extending the syntax of BPF object section names, this patch allows
user to attach BPF programs to symbol in modules. For example:

 SEC("module=i915\n"
     "parse_cmds=i915_parse_cmds")
 int parse_cmds(void *ctx)
 {
     return 1;
 }

Implementation is very simple: like what 'perf probe' does, for module,
fill 'uprobe' field in 'struct perf_probe_event'. Other parts would be
done automatically.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: David Ahern <dsahern@gmail.com>
Cc: He Kuang <hekuang@huawei.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kaixu Xia <xiakaixu@huawei.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Link: http://lkml.kernel.org/n/1445915248-175553-1-git-send-email-wangnan0@huawei.com
---
 tools/perf/util/bpf-loader.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/tools/perf/util/bpf-loader.c b/tools/perf/util/bpf-loader.c
index 54bfe62..aeac08c 100644
--- a/tools/perf/util/bpf-loader.c
+++ b/tools/perf/util/bpf-loader.c
@@ -119,6 +119,16 @@ config__exec(const char *value, struct perf_probe_event *pev)
 	return 0;
 }
 
+static int
+config__module(const char *value, struct perf_probe_event *pev)
+{
+	pev->uprobes = false;
+	pev->target = strdup(value);
+	if (!pev->target)
+		return -ENOMEM;
+	return 0;
+}
+
 static struct {
 	const char *key;
 	const char *usage;
@@ -131,6 +141,12 @@ static struct {
 		.desc	= "Set uprobe target",
 		.func	= config__exec,
 	},
+	{
+		.key	= "module",
+		.usage	= "module=<module name>    ",
+		.desc	= "Set kprobe module",
+		.func	= config__module,
+	}
 };
 
 static int
-- 
1.8.3.4