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/20200625100516.365338-2-tz.stoyanov@gmail.com
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
[ Ported from trace-cmd.git ]
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: linux-trace-devel@vger.kernel.org
Link: http://lore.kernel.org/lkml/20200702185703.619656282@goodmis.org
Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/lib/traceevent/kbuffer-parse.c b/tools/lib/traceevent/kbuffer-parse.c
index 27f3b07fdae8bed2a5f02118b2933cca82ac46f0..583db99aee94b11e8cd85b7bb1ba6e930360551c 100644 (file)
--- a/tools/lib/traceevent/kbuffer-parse.c
+++ b/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

diff --git a/tools/lib/traceevent/kbuffer.h b/tools/lib/traceevent/kbuffer.h
index ed4d697fc137861d9b98a23daef9f19d5e58da59..5fa8292e341b3da8fbd7be8af4744e5726006bb8 100644 (file)
--- a/tools/lib/traceevent/kbuffer.h
+++ b/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);