To allow BPF filters for unprivileged users it needs to pin the BPF
objects to BPF-fs first.  Let's add a new option to pin and unpin the
objects easily.  I'm not sure 'perf record' is a right place to do this
but I don't have a better idea right now.

  $ sudo perf record --setup-filter pin

The above command would pin BPF program and maps for the filter when the
system has BPF-fs (usually at /sys/fs/bpf/).  To unpin the objects,
users can run the following command (as root).

  $ sudo perf record --setup-filter unpin

Committer testing:

  root@number:~# perf record --setup-filter pin
  root@number:~# ls -la /sys/fs/bpf/perf_filter/
  total 0
  drwxr-xr-x. 2 root root 0 Jul 31 10:43 .
  drwxr-xr-t. 3 root root 0 Jul 31 10:43 ..
  -rw-rw-rw-. 1 root root 0 Jul 31 10:43 dropped
  -rw-rw-rw-. 1 root root 0 Jul 31 10:43 filters
  -rwxrwxrwx. 1 root root 0 Jul 31 10:43 perf_sample_filter
  -rw-rw-rw-. 1 root root 0 Jul 31 10:43 pid_hash
  -rw-------. 1 root root 0 Jul 31 10:43 sample_f_rodata
  root@number:~# ls -la /sys/fs/bpf/perf_filter/perf_sample_filter
  -rwxrwxrwx. 1 root root 0 Jul 31 10:43 /sys/fs/bpf/perf_filter/perf_sample_filter
  root@number:~#
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: KP Singh <kpsingh@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Song Liu <song@kernel.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: bpf@vger.kernel.org
Link: https://lore.kernel.org/r/20240703223035.2024586-8-namhyung@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>