reading dynamic array fields in ftrace

hi, some of the events in ftrace have dynamic array fields. Like : field:__data_loc char[] arg1; offset:24; size:4; signed:1; If i am sampling this particular event using perf_event_open(), how do i read this field i tried: #define get_str(field) (char *)get_dynamic_array(field) #define get_dynamic_array(field) \ ((void *)data + (data->__data_loc_##field & 0xffff)) as done in include/trace/ftrace,h But it gives garble data. TID:28578 PID:28578 TIME:258203626722378 CPU:4 Filename: ^\~@b�^O~H��^H�^? Will appreciate any help. Thanks -sahil