selftests/bpf: Fix return value checks in perf_event_stackmap test

The bpf_get_stackid() function may also return 0 on success as per UAPI BPF
helper documentation. Therefore, correct checks from 'val > 0' to 'val >= 0'
to ensure that they cover all possible success return values.

Signed-off-by: Yuntao Wang <ytcoode@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20220408041452.933944-1-ytcoode@gmail.com

selftests/bpf: Use BTF-defined key/value for map definitions

Change map definitions in BPF selftests to use BTF-defined
key/value types. This unifies the map definitions and ensures
libbpf won't emit warning about retrying map creation.

Signed-off-by: Hengqi Chen <hengqi.chen@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210930161456.3444544-3-hengqi.chen@gmail.com

selftests/bpf: Add callchain_stackid

This tests new helper function bpf_get_stackid_pe and bpf_get_stack_pe.
These two helpers have different implementation for perf_event with PEB
entries.

Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200723180648.1429892-5-songliubraving@fb.com