selftests/bpf: add bpf_cookie selftests for high-level APIs
Add selftest with few subtests testing proper bpf_cookie usage.
Kprobe and uprobe subtests are pretty straightforward and just validate that
the same BPF program attached with different bpf_cookie will be triggered with
those different bpf_cookie values.
Tracepoint subtest is a bit more interesting, as it is the only
perf_event-based BPF hook that shares bpf_prog_array between multiple
perf_events internally. This means that the same BPF program can't be attached
to the same tracepoint multiple times. So we have 3 identical copies. This
arrangement allows to test bpf_prog_array_copy()'s handling of bpf_prog_array
list manipulation logic when programs are attached and detached. The test
validates that bpf_cookie isn't mixed up and isn't lost during such list
manipulations.
Perf_event subtest validates that two BPF links can be created against the
same perf_event (but not at the same time, only one BPF program can be
attached to perf_event itself), and that for each we can specify different
bpf_cookie value.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
2 files changed
