On Dec 3, 2021, at 5:10 AM, Arnaldo Carvalho de Melo [off-list ref] wrote:

Hi Song,

	So I'm changing all my containers to build with BUILD_BPF_SKEL=1
to then make this the default, so far older containers fail either
because the clang available is too old, so I've added a NO_BUILD_BPF_SKEL=1
env var to disable that in those containers and then there is this other
case where clang is recent enough but:

   util/bpf_skel/bperf_leader.bpf.c:13:20: error: use of undeclared identifier 'BPF_F_PRESERVE_ELEMS'
           __uint(map_flags, BPF_F_PRESERVE_ELEMS);

Because the system's /usr/include/linux/bpf.h doesn't have that
BPF_F_PRESERVE_ELEMS enum entry.

These are enums to make them available via BTF, but then I can't use
the:

#ifdef BPF_F_PRESERVE_ELEMS
#define BPF_F_PRESERVE_ELEMS (1U << 11)
#endif

approach.

But then we _have_ it in the tools/include/uapi/linux/bpf.h we ship:

$ grep BPF_F_PRESERVE_ELEMS tools/include/uapi/linux/bpf.h
	BPF_F_PRESERVE_ELEMS	= (1U << 11),
$

so we need to switch to using it somehow, this way we can build in more
systems and make bperf and other BPF enabled features.

From a quick look I couldn't find where to add
$(sourcedir)/tools/include/uapi/ to the include path used to build
util/bpf_skel/bperf_leader.bpf.c, should be easy, can you take a look?

Thanks,

- Arnaldo

I think the following should fix it

Thanks,
Song

diff --git i/tools/perf/util/bpf_skel/bperf_follower.bpf.c w/tools/perf/util/bpf_skel/bperf_follower.bpf.c
index b8fa3cb2da230..4a6acfde14937 100644
--- i/tools/perf/util/bpf_skel/bperf_follower.bpf.c
+++ w/tools/perf/util/bpf_skel/bperf_follower.bpf.c

@@ -1,7 +1,6 @@
 // SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
 // Copyright (c) 2021 Facebook
-#include <linux/bpf.h>
-#include <linux/perf_event.h>
+#include "vmlinux.h"
 #include <bpf/bpf_helpers.h>
 #include <bpf/bpf_tracing.h>
 #include "bperf.h"

diff --git i/tools/perf/util/bpf_skel/bperf_leader.bpf.c w/tools/perf/util/bpf_skel/bperf_leader.bpf.c
index 4f70d1459e86c..40d962b058634 100644
--- i/tools/perf/util/bpf_skel/bperf_leader.bpf.c
+++ w/tools/perf/util/bpf_skel/bperf_leader.bpf.c

@@ -1,7 +1,6 @@
 // SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
 // Copyright (c) 2021 Facebook
-#include <linux/bpf.h>
-#include <linux/perf_event.h>
+#include "vmlinux.h"
 #include <bpf/bpf_helpers.h>
 #include <bpf/bpf_tracing.h>
 #include "bperf.h"

diff --git i/tools/perf/util/bpf_skel/bpf_prog_profiler.bpf.c w/tools/perf/util/bpf_skel/bpf_prog_profiler.bpf.c
index ab12b4c4ece21..97037d3b3d9fa 100644
--- i/tools/perf/util/bpf_skel/bpf_prog_profiler.bpf.c
+++ w/tools/perf/util/bpf_skel/bpf_prog_profiler.bpf.c

@@ -1,6 +1,6 @@
 // SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
 // Copyright (c) 2020 Facebook
-#include <linux/bpf.h>
+#include "vmlinux.h"
 #include <bpf/bpf_helpers.h>
 #include <bpf/bpf_tracing.h>