tools lib traceevent: Add API to read time information from kbuffer

Add the functions kbuffer_subbuf_timestamp() and kbuffer_ptr_delta() to
get the timing data stored in the ring buffer that is used to produced
the time stamps of the records.

This is useful for tools like trace-cmd to be able to display the
content of the read data to understand why the records show the time
stamps that they do.

Link: http://lore.kernel.org/linux-trace-devel/[email protected]

Signed-off-by: Steven Rostedt (VMware) <[email protected]>
[ Ported from trace-cmd.git ]
Cc: Andrew Morton <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: [email protected]
Link: http://lore.kernel.org/lkml/[email protected]
Signed-off-by: Tzvetomir Stoyanov (VMware) <[email protected]>
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

Author: rostedt

tools/lib/traceevent/kbuffer-parse.c

@@ -546,6 +546,34 @@ int kbuffer_load_subbuffer(struct kbuffer *kbuf, void *subbuffer)
 	return 0;
 }
 
+/**
+ * kbuffer_subbuf_timestamp - read the timestamp from a sub buffer
+ * @kbuf:      The kbuffer to load
+ * @subbuf:    The subbuffer to read from.
+ *
+ * Return the timestamp from a subbuffer.
+ */
+unsigned long long kbuffer_subbuf_timestamp(struct kbuffer *kbuf, void *subbuf)
+{
+	return kbuf->read_8(subbuf);
+}
+
+/**
+ * kbuffer_ptr_delta - read the delta field from a record
+ * @kbuf:      The kbuffer to load
+ * @ptr:       The record in the buffe.
+ *
+ * Return the timestamp delta from a record
+ */
+unsigned int kbuffer_ptr_delta(struct kbuffer *kbuf, void *ptr)
+{
+	unsigned int type_len_ts;
+
+	type_len_ts = read_4(kbuf, ptr);
+	return ts4host(kbuf, type_len_ts);
+}
+
+
 /**
  * kbuffer_read_event - read the next event in the kbuffer subbuffer
  * @kbuf:	The kbuffer to read from

tools/lib/traceevent/kbuffer.h

@@ -49,6 +49,8 @@ int kbuffer_load_subbuffer(struct kbuffer *kbuf, void *subbuffer);
 void *kbuffer_read_event(struct kbuffer *kbuf, unsigned long long *ts);
 void *kbuffer_next_event(struct kbuffer *kbuf, unsigned long long *ts);
 unsigned long long kbuffer_timestamp(struct kbuffer *kbuf);
+unsigned long long kbuffer_subbuf_timestamp(struct kbuffer *kbuf, void *subbuf);
+unsigned int kbuffer_ptr_delta(struct kbuffer *kbuf, void *ptr);
 
 void *kbuffer_translate_data(int swap, void *data, unsigned int *size);