diff --git a/kernel/events/core.c b/kernel/events/core.c
index e453589..3f1f77d 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -6555,6 +6555,11 @@ static void perf_output_read(struct perf_output_handle *handle,
 		perf_output_read_one(handle, event, enabled, running);
 }
 
+static inline bool perf_sample_save_hw_index(struct perf_event *event)
+{
+	return event->attr.branch_sample_type & PERF_SAMPLE_BRANCH_HW_INDEX;
+}
+
 void perf_output_sample(struct perf_output_handle *handle,
 			struct perf_event_header *header,
 			struct perf_sample_data *data,
@@ -6643,6 +6648,8 @@ void perf_output_sample(struct perf_output_handle *handle,
 			     * sizeof(struct perf_branch_entry);
 
 			perf_output_put(handle, data->br_stack->nr);
+			if (perf_sample_save_hw_index(event))
+				perf_output_put(handle, data->br_stack->hw_idx);
 			perf_output_copy(handle, data->br_stack->entries, size);
 		} else {
 			/*
@@ -6836,6 +6843,9 @@ void perf_prepare_sample(struct perf_event_header *header,
 	if (sample_type & PERF_SAMPLE_BRANCH_STACK) {
 		int size = sizeof(u64); /* nr */
 		if (data->br_stack) {
+			if (perf_sample_save_hw_index(event))
+				size += sizeof(u64);
+
 			size += data->br_stack->nr
 			      * sizeof(struct perf_branch_entry);
 		}