perf db-export: Add calls parent_id to enable creation of call trees

The call_path can be used to find the parent symbol for a call but not
the exact parent call. To do that add parent_id to the call_return
export. This enables the creation of a call tree from the exported data.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: https://lkml.kernel.org/n/tip-6j7tzdxo67cox6kan7k22oo6@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 14 insertions, 2 deletions

diff --git a/tools/perf/util/thread-stack.c b/tools/perf/util/thread-stack.c
index a8b45168513c..41942c2aaa18 100644
--- a/tools/perf/util/thread-stack.c
+++ b/tools/perf/util/thread-stack.c
@@ -49,6 +49,7 @@ enum retpoline_state_t {
  * @timestamp: timestamp (if known)
  * @ref: external reference (e.g. db_id of sample)
  * @branch_count: the branch count when the entry was created
+ * @db_id: id used for db-export
  * @cp: call path
  * @no_call: a 'call' was not seen
  * @trace_end: a 'call' but trace ended
@@ -59,6 +60,7 @@ struct thread_stack_entry {
 	u64 timestamp;
 	u64 ref;
 	u64 branch_count;
+	u64 db_id;
 	struct call_path *cp;
 	bool no_call;
 	bool trace_end;
@@ -280,12 +282,14 @@ static int thread_stack__call_return(struct thread *thread,
 		.comm = ts->comm,
 		.db_id = 0,
 	};
+	u64 *parent_db_id;
 
 	tse = &ts->stack[idx];
 	cr.cp = tse->cp;
 	cr.call_time = tse->timestamp;
 	cr.return_time = timestamp;
 	cr.branch_count = ts->branch_count - tse->branch_count;
+	cr.db_id = tse->db_id;
 	cr.call_ref = tse->ref;
 	cr.return_ref = ref;
 	if (tse->no_call)
@@ -295,7 +299,14 @@ static int thread_stack__call_return(struct thread *thread,
 	if (tse->non_call)
 		cr.flags |= CALL_RETURN_NON_CALL;
 
-	return crp->process(&cr, crp->data);
+	/*
+	 * The parent db_id must be assigned before exporting the child. Note
+	 * it is not possible to export the parent first because its information
+	 * is not yet complete because its 'return' has not yet been processed.
+	 */
+	parent_db_id = idx ? &(tse - 1)->db_id : NULL;
+
+	return crp->process(&cr, parent_db_id, crp->data);
 }
 
 static int __thread_stack__flush(struct thread *thread, struct thread_stack *ts)
@@ -484,7 +495,7 @@ void thread_stack__sample(struct thread *thread, int cpu,
 }
 
 struct call_return_processor *
-call_return_processor__new(int (*process)(struct call_return *cr, void *data),
+call_return_processor__new(int (*process)(struct call_return *cr, u64 *parent_db_id, void *data),
 			   void *data)
 {
 	struct call_return_processor *crp;
@@ -537,6 +548,7 @@ static int thread_stack__push_cp(struct thread_stack *ts, u64 ret_addr,
 	tse->no_call = no_call;
 	tse->trace_end = trace_end;
 	tse->non_call = false;
+	tse->db_id = 0;
 
 	return 0;
 }