[PATCH bpf-next 01/11] bpf, perf: fix bpftool compilation with !CONFIG_PERF_EVENTS

[Alexander Lobakin <alobakin@pm.me>]

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.
Move CONFIG_BPF_SYSCALL block out of the CONFIG_PERF_EVENTS block
to make it available unconditionally.

Fixes: cbdaf71f7e65 ("bpftool: Add bpf_cookie to link output")
Signed-off-by: Alexander Lobakin <alobakin@pm.me>
---
 include/linux/perf_event.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index af97dd427501..b1d5715b8b34 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -762,12 +762,14 @@ struct perf_event {
 	u64				(*clock)(void);
 	perf_overflow_handler_t		overflow_handler;
 	void				*overflow_handler_context;
+#endif /* CONFIG_PERF_EVENTS */
 #ifdef CONFIG_BPF_SYSCALL
 	perf_overflow_handler_t		orig_overflow_handler;
 	struct bpf_prog			*prog;
 	u64				bpf_cookie;
 #endif

+#ifdef CONFIG_PERF_EVENTS
 #ifdef CONFIG_EVENT_TRACING
 	struct trace_event_call		*tp_event;
 	struct event_filter		*filter;
--
2.35.2