linux-kernel - [PATCH 04/15] tools/lib/traceevent: Add more debugging to see various internal ring buffer entries

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Date:   Mon, 01 Apr 2019 12:43:09 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     linux-kernel@...r.kernel.org
Cc:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Ingo Molnar <mingo@...nel.org>, Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Tzvetomir Stoyanov <tstoyanov@...are.com>
Subject: [PATCH 04/15] tools/lib/traceevent: Add more debugging to see various internal ring
 buffer entries

From: "Steven Rostedt (Red Hat)" <rostedt@...dmis.org>

When trace-cmd report --debug is set, show the internal ring buffer entries
like time-extends and padding. This requires adding new kbuffer API to
retrieve these items.

Signed-off-by: Steven Rostedt (VMware) <rostedt@...dmis.org>
---
 tools/lib/traceevent/kbuffer-parse.c | 49 ++++++++++++++++++++++++++++
 tools/lib/traceevent/kbuffer.h       | 13 ++++++++
 2 files changed, 62 insertions(+)

diff --git a/tools/lib/traceevent/kbuffer-parse.c b/tools/lib/traceevent/kbuffer-parse.c
index af2a1f3b7424..b887e7437d67 100644
--- a/tools/lib/traceevent/kbuffer-parse.c
+++ b/tools/lib/traceevent/kbuffer-parse.c
@@ -727,3 +727,52 @@ int kbuffer_start_of_data(struct kbuffer *kbuf)
 {
 	return kbuf->start;
 }
+
+/**
+ * kbuffer_raw_get - get raw buffer info
+ * @kbuf:	The kbuffer
+ * @subbuf:	Start of mapped subbuffer
+ * @info:	Info descriptor to fill in
+ *
+ * For debugging. This can return internals of the ring buffer.
+ * Expects to have info->next set to what it will read.
+ * The type, length and timestamp delta will be filled in, and
+ * @info->next will be updated to the next element.
+ * The @subbuf is used to know if the info is passed the end of
+ * data and NULL will be returned if it is.
+ */
+struct kbuffer_raw_info *
+kbuffer_raw_get(struct kbuffer *kbuf, void *subbuf, struct kbuffer_raw_info *info)
+{
+	unsigned long long flags;
+	unsigned long long delta;
+	unsigned int type_len;
+	unsigned int size;
+	int start;
+	int length;
+	void *ptr = info->next;
+
+	if (!kbuf || !subbuf)
+		return NULL;
+
+	if (kbuf->flags & KBUFFER_FL_LONG_8)
+		start = 16;
+	else
+		start = 12;
+
+	flags = read_long(kbuf, subbuf + 8);
+	size = (unsigned int)flags & COMMIT_MASK;
+
+	if (ptr < subbuf || ptr >= subbuf + start + size)
+		return NULL;
+
+	type_len = translate_data(kbuf, ptr, &ptr, &delta, &length);
+
+	info->next = ptr + length;
+
+	info->type = type_len;
+	info->delta = delta;
+	info->length = length;
+
+	return info;
+}
diff --git a/tools/lib/traceevent/kbuffer.h b/tools/lib/traceevent/kbuffer.h
index 03dce757553f..ed4d697fc137 100644
--- a/tools/lib/traceevent/kbuffer.h
+++ b/tools/lib/traceevent/kbuffer.h
@@ -65,4 +65,17 @@ int kbuffer_subbuffer_size(struct kbuffer *kbuf);
 void kbuffer_set_old_format(struct kbuffer *kbuf);
 int kbuffer_start_of_data(struct kbuffer *kbuf);
 
+/* Debugging */
+
+struct kbuffer_raw_info {
+	int			type;
+	int			length;
+	unsigned long long	delta;
+	void			*next;
+};
+
+/* Read raw data */
+struct kbuffer_raw_info *kbuffer_raw_get(struct kbuffer *kbuf, void *subbuf,
+					 struct kbuffer_raw_info *info);
+
 #endif /* _K_BUFFER_H */
-- 
2.20.1