When CONFIG_PERF_EVENTS is not set, struct perf_event remains empty.
However, the structure is being used by bpftool indirectly via BTF.
This leads to:
skeleton/pid_iter.bpf.c:49:30: error: no member named 'bpf_cookie' in 'struct perf_event'
return BPF_CORE_READ(event, bpf_cookie);
~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~
...
skeleton/pid_iter.bpf.c:49:9: error: returning 'void' from a function with incompatible result type '__u64' (aka 'unsigned long long')
return BPF_CORE_READ(event, bpf_cookie);
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Tools and samples can't use any CONFIG_ definitions, so the fields
used there should always be present.
Define struct perf_event___local with the `preserve_access_index`
attribute inside the pid_iter BPF prog to allow compiling on any
configs. CO-RE will substitute it with the real struct perf_event
accesses later on.
Fixes: cbdaf71f7e ("bpftool: Add bpf_cookie to link output")
Suggested-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexander Lobakin <alobakin@pm.me>
Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20230707095425.168126-2-quentin@isovalent.com
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