4 files changed, 48 insertions, 1 deletions

diff --git a/include/linux/ring_buffer.h b/include/linux/ring_buffer.h
index 7d9eb39fa76a..025159e17e1b 100644
--- a/include/linux/ring_buffer.h
+++ b/include/linux/ring_buffer.h
@@ -178,6 +178,8 @@ void ring_buffer_normalize_time_stamp(struct ring_buffer *buffer,
                                       int cpu, u64 *ts);
 void ring_buffer_set_clock(struct ring_buffer *buffer,
                            u64 (*clock)(void));
+void ring_buffer_set_time_stamp_abs(struct ring_buffer *buffer, bool abs);
+bool ring_buffer_time_stamp_abs(struct ring_buffer *buffer);
 
 size_t ring_buffer_page_len(void *page);
 
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index dcf1c4dd3efe..2a03e069bbc6 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -488,6 +488,7 @@ struct ring_buffer {
         u64                             (*clock)(void);
 
         struct rb_irq_work              irq_work;
+        bool                            time_stamp_abs;
 };
 
 struct ring_buffer_iter {
@@ -1382,6 +1383,16 @@ void ring_buffer_set_clock(struct ring_buffer *buffer,
         buffer->clock = clock;
 }
 
+void ring_buffer_set_time_stamp_abs(struct ring_buffer *buffer, bool abs)
+{
+        buffer->time_stamp_abs = abs;
+}
+
+bool ring_buffer_time_stamp_abs(struct ring_buffer *buffer)
+{
+        return buffer->time_stamp_abs;
+}
+
 static void rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer);
 
 static inline unsigned long rb_page_entries(struct buffer_page *bpage)
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 20a2300ae4e8..cba003f0362e 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2269,7 +2269,7 @@ trace_event_buffer_lock_reserve(struct ring_buffer **current_rb,
 
         *current_rb = trace_file->tr->trace_buffer.buffer;
 
-        if ((trace_file->flags &
+        if (!ring_buffer_time_stamp_abs(*current_rb) && (trace_file->flags &
              (EVENT_FILE_FL_SOFT_DISABLED | EVENT_FILE_FL_FILTERED)) &&
             (entry = this_cpu_read(trace_buffered_event))) {
                 /* Try to use the per cpu buffer first */
@@ -6282,6 +6282,37 @@ static int tracing_clock_open(struct inode *inode, struct file *file)
         return ret;
 }
 
+int tracing_set_time_stamp_abs(struct trace_array *tr, bool abs)
+{
+        int ret = 0;
+
+        mutex_lock(&trace_types_lock);
+
+        if (abs && tr->time_stamp_abs_ref++)
+                goto out;
+
+        if (!abs) {
+                if (WARN_ON_ONCE(!tr->time_stamp_abs_ref)) {
+                        ret = -EINVAL;
+                        goto out;
+                }
+
+                if (--tr->time_stamp_abs_ref)
+                        goto out;
+        }
+
+        ring_buffer_set_time_stamp_abs(tr->trace_buffer.buffer, abs);
+
+#ifdef CONFIG_TRACER_MAX_TRACE
+        if (tr->max_buffer.buffer)
+                ring_buffer_set_time_stamp_abs(tr->max_buffer.buffer, abs);
+#endif
+ out:
+        mutex_unlock(&trace_types_lock);
+
+        return ret;
+}
+
 struct ftrace_buffer_info {
         struct trace_iterator   iter;
         void                    *spare;
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 2a6d0325a761..477341710ebf 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -273,6 +273,7 @@ struct trace_array {
         /* function tracing enabled */
         int                     function_enabled;
 #endif
+        int                     time_stamp_abs_ref;
 };
 
 enum {
@@ -286,6 +287,8 @@ extern struct mutex trace_types_lock;
 extern int trace_array_get(struct trace_array *tr);
 extern void trace_array_put(struct trace_array *tr);
 
+extern int tracing_set_time_stamp_abs(struct trace_array *tr, bool abs);
+
 /*
  * The global tracer (top) should be the first trace array added,
  * but we check the flag anyway.