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Date:   Thu, 14 Apr 2022 22:44:48 +0000
To:     Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Andrii Nakryiko <andrii@kernel.org>
From:   Alexander Lobakin <alobakin@pm.me>
Cc:     Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
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Reply-To: Alexander Lobakin <alobakin@pm.me>
Subject: [PATCH bpf-next 01/11] bpf, perf: fix bpftool compilation with !CONFIG_PERF_EVENTS
Message-ID: <20220414223704.341028-2-alobakin@pm.me>
In-Reply-To: <20220414223704.341028-1-alobakin@pm.me>
References: <20220414223704.341028-1-alobakin@pm.me>
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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 'stru=
ct 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 {
 =09u64=09=09=09=09(*clock)(void);
 =09perf_overflow_handler_t=09=09overflow_handler;
 =09void=09=09=09=09*overflow_handler_context;
+#endif /* CONFIG_PERF_EVENTS */
 #ifdef CONFIG_BPF_SYSCALL
 =09perf_overflow_handler_t=09=09orig_overflow_handler;
 =09struct bpf_prog=09=09=09*prog;
 =09u64=09=09=09=09bpf_cookie;
 #endif

+#ifdef CONFIG_PERF_EVENTS
 #ifdef CONFIG_EVENT_TRACING
 =09struct trace_event_call=09=09*tp_event;
 =09struct event_filter=09=09*filter;
--
2.35.2