/usr/lib/linux-tools/3.13.0-121-generic/perf is in linux-tools-3.13.0-121-generic 3.13.0-121.170.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/linux-tools/3.13.0-121-generic/../../linux-tools-3.13.0-121/perf