2 files changed, 16 insertions, 1 deletions

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 240423a9d1af..4a904623e05d 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -205,7 +205,8 @@ static DEFINE_MUTEX(trace_types_lock);
 static DECLARE_WAIT_QUEUE_HEAD(trace_wait);
 
 /* trace_flags holds trace_options default values */
-unsigned long trace_flags = TRACE_ITER_PRINT_PARENT | TRACE_ITER_PRINTK;
+unsigned long trace_flags = TRACE_ITER_PRINT_PARENT | TRACE_ITER_PRINTK |
+        TRACE_ITER_ANNOTATE;
 
 /**
  * trace_wake_up - wake up tasks waiting for trace input
@@ -261,6 +262,7 @@ static const char *trace_options[] = {
 #ifdef CONFIG_BRANCH_TRACER
         "branch",
 #endif
+        "annotate",
         NULL
 };
 
@@ -1113,6 +1115,7 @@ void tracing_stop_function_trace(void)
 
 enum trace_file_type {
         TRACE_FILE_LAT_FMT      = 1,
+        TRACE_FILE_ANNOTATE     = 2,
 };
 
 static void trace_iterator_increment(struct trace_iterator *iter, int cpu)
@@ -1532,6 +1535,12 @@ static void test_cpu_buff_start(struct trace_iterator *iter)
 {
         struct trace_seq *s = &iter->seq;
 
+        if (!(trace_flags & TRACE_ITER_ANNOTATE))
+                return;
+
+        if (!(iter->iter_flags & TRACE_FILE_ANNOTATE))
+                return;
+
         if (cpu_isset(iter->cpu, iter->started))
                 return;
 
@@ -2132,6 +2141,11 @@ __tracing_open(struct inode *inode, struct file *file, int *ret)
         iter->trace = current_trace;
         iter->pos = -1;
 
+        /* Annotate start of buffers if we had overruns */
+        if (ring_buffer_overruns(iter->tr->buffer))
+                iter->iter_flags |= TRACE_FILE_ANNOTATE;
+
+
         for_each_tracing_cpu(cpu) {
 
                 iter->buffer_iter[cpu] =
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 9e015f5bea1d..790ea8c0e1f3 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -473,6 +473,7 @@ enum trace_iterator_flags {
 #ifdef CONFIG_BRANCH_TRACER
         TRACE_ITER_BRANCH               = 0x1000,
 #endif
+        TRACE_ITER_ANNOTATE             = 0x2000,
 };
 
 /*