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

[Masami Hiramatsu]

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

Signed-off-by: Masami Hiramatsu <mhira...@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;
        }