Hmm, apparently /usr/bin/perf is only a wrapper script that runs the "right" version of the perf executable for the current kernel. But the perf executable (typically inside /usr/lib/linux-tools-VERSION) is part of the "linux-tools-VERSION" package.
So if I do:
$ sudo apt install linux-tools-4.15.0-47/bionic-proposed
and then run /usr/lib/linux-tools-4.15.0-47/perf directly, instead of the wrapper script which will still run the perf version for the LTS kernel, things finally work here.
Hmm, apparently /usr/bin/perf is only a wrapper script that runs the "right" version of the perf executable for the current kernel. But the perf executable (typically inside /usr/lib/ linux-tools- VERSION) is part of the "linux- tools-VERSION" package.
So if I do: 4.15.0- 47/bionic- proposed
$ sudo apt install linux-tools-
and then run /usr/lib/ linux-tools- 4.15.0- 47/perf directly, instead of the wrapper script which will still run the perf version for the LTS kernel, things finally work here.