linux-kernel - [RFC PATCH 3/3] perf tools: Support attach BPF program on uprobe events

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Message-ID: <1435228645-116055-4-git-send-email-wangnan0@huawei.com>
Date:	Thu, 25 Jun 2015 10:37:25 +0000
From:	Wang Nan <wangnan0@...wei.com>
To:	<acme@...nel.org>, <ast@...mgrid.com>, <brendan.d.gregg@...il.com>,
	<daniel@...earbox.net>, <namhyung@...nel.org>,
	<masami.hiramatsu.pt@...achi.com>, <paulus@...ba.org>,
	<a.p.zijlstra@...llo.nl>, <mingo@...hat.com>, <jolsa@...nel.org>,
	<dsahern@...il.com>
CC:	<linux-kernel@...r.kernel.org>, <lizefan@...wei.com>,
	<hekuang@...wei.com>, <xiakaixu@...wei.com>, <pi3orama@....com>
Subject: [RFC PATCH 3/3] perf tools: Support attach BPF program on uprobe events

This patch append new syntax to BPF object section name to support
probing at uprobe event. Now we can use BPF program like this:

 SEC(
 "target:/lib64/libc.so.6\n"
 "libcwrite=__write"
 )
 int libcwrite(void *ctx)
 {
     return 1;
 }

Where, in section name of a program, before the main config string,
we can use 'key:value' style options. Now the only option key "target"
is for uprobe probing.

Signed-off-by: Wang Nan <wangnan0@...wei.com>
---
 tools/perf/util/bpf-loader.c | 78 ++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 71 insertions(+), 7 deletions(-)

diff --git a/tools/perf/util/bpf-loader.c b/tools/perf/util/bpf-loader.c
index 55843d8..2898f9c 100644
--- a/tools/perf/util/bpf-loader.c
+++ b/tools/perf/util/bpf-loader.c
@@ -73,6 +73,74 @@ bpf_prog_priv__clear(struct bpf_program *prog __maybe_unused,
 }
 
 static int
+do_config(const char *key, const char *value,
+	  struct perf_probe_event *pev)
+{
+	pr_debug("config bpf program: %s:%s\n", key, value);
+	if (strcmp(key, "target") == 0) {
+		pev->uprobes = true;
+		pev->target = strdup(value);
+	}
+
+	return 0;
+}
+
+static const char *
+parse_config_kvpair(const char *config_str, struct perf_probe_event *pev)
+{
+	char *text = strdup(config_str);
+	char *sep, *line;
+	const char *main_str = NULL;
+	int err = 0;
+
+	if (!text) {
+		pr_err("No enough memory: dup config_str failed\n");
+		return NULL;
+	}
+
+	line = text;
+	while ((sep = strchr(line, '\n'))) {
+		char *semi;
+
+		*sep = '\0';
+		semi = strchr(line, ':');
+		if (!semi)
+			goto nextline;
+		*semi = '\0';
+		if ((err = do_config(line, semi + 1, pev)))
+			break;
+nextline:
+		line = sep + 1;
+	}
+
+	if (!err)
+		main_str = config_str + (line - text);
+	free(text);
+
+	return main_str;
+}
+
+static int
+parse_config_pev(const char *config_str, struct perf_probe_event *pev)
+{
+	const char *main_str;
+	int err;
+
+	main_str = parse_config_kvpair(config_str, pev);
+	if (!main_str)
+		return -EINVAL;
+
+	err = parse_perf_probe_command(main_str, pev);
+	if (err < 0) {
+		pr_err("bpf: '%s' is not a valid config string\n",
+		       config_str);
+		/* parse failed, don't need clear pev. */
+		return -EINVAL;
+	}
+	return 0;
+}
+
+static int
 config_bpf_program(struct bpf_program *prog)
 {
 	struct perf_probe_event *pev = alloc_perf_probe_event();
@@ -91,13 +159,9 @@ config_bpf_program(struct bpf_program *prog)
 	}
 
 	pr_debug("bpf: config program '%s'\n", config_str);
-	err = parse_perf_probe_command(config_str, pev);
-	if (err < 0) {
-		pr_err("bpf: '%s' is not a valid config string\n",
-		       config_str);
-		/* parse failed, don't need clear pev. */
-		return -EINVAL;
-	}
+	err = parse_config_pev(config_str, pev);
+	if (err)
+		return err;
 
 	if (pev->group && strcmp(pev->group, PERF_BPF_PROBE_GROUP)) {
 		pr_err("bpf: '%s': group for event is set and not '%s'.\n",
-- 
1.8.3.4

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