From: Yoshiki Komachi <komachi.yoshiki@gmail.com>
Date: Tue, 21 Apr 2020 09:05:27 +0900
Subject: bpf_helpers.h: Add note for building with vmlinux.h or linux/types.h
Patch-mainline: v5.8-rc1
Git-commit: ae460c022453337850bdc36a36bf7596a6cfcf99
References: bsc#1177028
The following error was shown when a bpf program was compiled without
vmlinux.h auto-generated from BTF:
# clang -I./linux/tools/lib/ -I/lib/modules/$(uname -r)/build/include/ \
-O2 -Wall -target bpf -emit-llvm -c bpf_prog.c -o bpf_prog.bc
...
In file included from linux/tools/lib/bpf/bpf_helpers.h:5:
linux/tools/lib/bpf/bpf_helper_defs.h:56:82: error: unknown type name '__u64'
...
It seems that bpf programs are intended for being built together with
the vmlinux.h (which will have all the __u64 and other typedefs). But
users may mistakenly think "include <linux/types.h>" is missing
because the vmlinux.h is not common for non-bpf developers. IMO, an
explicit comment therefore should be added to bpf_helpers.h as this
patch shows.
Signed-off-by: Yoshiki Komachi <komachi.yoshiki@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/1587427527-29399-1-git-send-email-komachi.yoshiki@gmail.com
Acked-by: Gary Lin <glin@suse.com>
---
tools/lib/bpf/bpf_helpers.h | 6 ++++++
1 file changed, 6 insertions(+)
--- a/tools/lib/bpf/bpf_helpers.h
+++ b/tools/lib/bpf/bpf_helpers.h
@@ -2,6 +2,12 @@
#ifndef __BPF_HELPERS__
#define __BPF_HELPERS__
+/*
+ * Note that bpf programs need to include either
+ * vmlinux.h (auto-generated from BTF) or linux/types.h
+ * in advance since bpf_helper_defs.h uses such types
+ * as __u64.
+ */
#include "bpf_helper_defs.h"
#define __uint(name, val) int (*name)[val]