[RFC PATCH 10/11] tracing: of: Add kprobe event support

Masami Hiramatsu
2019-06-21T16:19:50Z

Add kprobe event support in event node. User can add probe definitions
by "probes" property as a string array.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
---
kernel/trace/trace_kprobe.c | 5 +++
kernel/trace/trace_of.c | 65 ++++++++++++++++++++++++++++++++++++-------
2 files changed, 60 insertions(+), 10 deletions(-)

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 5166a12a9d49..cc5ba13028cd 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -765,6 +765,11 @@ static int create_or_delete_trace_kprobe(int argc, char **argv)
return ret == -ECANCELED ? -EINVAL : ret;
}

+int trace_kprobe_run_command(const char *command)
+{
+ return trace_run_command(command, create_or_delete_trace_kprobe);
+}
+
static int trace_kprobe_release(struct dyn_event *ev)
{
struct trace_kprobe *tk = to_trace_kprobe(ev);
diff --git a/kernel/trace/trace_of.c b/kernel/trace/trace_of.c
index 696f59234e62..43d87e5065a3 100644
--- a/kernel/trace/trace_of.c
+++ b/kernel/trace/trace_of.c
@@ -23,6 +23,7 @@ extern void __init trace_init_tracepoint_printk(void);
extern ssize_t tracing_resize_ring_buffer(struct trace_array *tr,
unsigned long size, int cpu_id);
extern int trigger_process_regex(struct trace_event_file *file, char *buff);
+extern int trace_kprobe_run_command(const char *command);

static void __init
trace_of_set_ftrace_options(struct trace_array *tr, struct device_node *node)
@@ -99,14 +100,47 @@ trace_of_enable_events(struct trace_array *tr, struct device_node *node)
}
}

+static int __init
+trace_of_add_kprobe_event(struct device_node *node,
+ const char *group, const char *event)
+{
+ struct property *prop;
+ char buf[MAX_BUF_LEN];
+ const char *p;
+ char *q;
+ int len, ret;
+
+ len = snprintf(buf, ARRAY_SIZE(buf) - 1, "p:%s/%s ", group, event);
+ if (len >= ARRAY_SIZE(buf)) {
+ pr_err("Event name is too long: %s\n", event);
+ return -E2BIG;
+ }
+ q = buf + len;
+ len = ARRAY_SIZE(buf) - len;
+
+ of_property_for_each_string(node, "probes", prop, p) {
+ if (strlcpy(q, p, len) >= len) {
+ pr_err("Probe definition is too long: %s\n", p);
+ return -E2BIG;
+ }
+ ret = trace_kprobe_run_command(buf);
+ if (ret < 0) {
+ pr_err("Failed to add probe: %s\n", buf);
+ return ret;
+ }
+ }
+
+ return 0;
+}
+
static void __init
trace_of_init_one_event(struct trace_array *tr, struct device_node *node)
{
struct trace_event_file *file;
struct property *prop;
char buf[MAX_BUF_LEN];
- char *bufp;
- const char *p;
+ const char *p, *group;
+ char *event;
int err;

if (!of_node_name_prefix(node, "event"))
@@ -123,18 +157,29 @@ trace_of_init_one_event(struct trace_array *tr, struct device_node *node)
pr_err("Event name is too long: %s\n", p);
return;
}
- bufp = buf;
-
- p = strsep(&bufp, ":");
- if (!bufp) {
- pr_err("%s has no group name\n", buf);
- return;
+ event = buf;
+
+ group = strsep(&event, ":");
+ /* For a kprobe event, we have to generates an event at first */
+ if (of_find_property(node, "probes", NULL)) {
+ if (!event) {
+ event = buf;
+ group = "kprobes";
+ }
+ err = trace_of_add_kprobe_event(node, group, event);
+ if (err < 0)
+ return;
+ } else {
+ if (!event) {
+ pr_err("%s has no group name\n", buf);
+ return;
+ }
}

mutex_lock(&event_mutex);
- file = find_event_file(tr, buf, bufp);
+ file = find_event_file(tr, group, event);
if (!file) {
- pr_err("Failed to find event: %s\n", buf);
+ pr_err("Failed to find event: %s:%s\n", group, event);
return;
}