From: Andrii Nakryiko <andriin@fb.com>
Date: Sat, 29 Feb 2020 15:11:09 -0800
Subject: bpftool: Add header guards to generated vmlinux.h
Patch-mainline: v5.7-rc1
Git-commit: ca7dc2791b507f842d73e46b1a0453b36b69ffc2
References: bsc#1177028

Add canonical #ifndef/#define/#endif guard for generated vmlinux.h header with
__VMLINUX_H__ symbol. __VMLINUX_H__ is also going to play double role of
identifying whether vmlinux.h is being used, versus, say, BCC or non-CO-RE
libbpf modes with dependency on kernel headers. This will make it possible to
write helper macro/functions, agnostic to exact BPF program set up.

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200229231112.1240137-2-andriin@fb.com
Acked-by: Gary Lin <glin@suse.com>
---
 tools/bpf/bpftool/btf.c |    5 +++++
 1 file changed, 5 insertions(+)

--- a/tools/bpf/bpftool/btf.c
+++ b/tools/bpf/bpftool/btf.c
@@ -389,6 +389,9 @@ static int dump_btf_c(const struct btf *
 	if (IS_ERR(d))
 		return PTR_ERR(d);
 
+	printf("#ifndef __VMLINUX_H__\n");
+	printf("#define __VMLINUX_H__\n");
+	printf("\n");
 	printf("#ifndef BPF_NO_PRESERVE_ACCESS_INDEX\n");
 	printf("#pragma clang attribute push (__attribute__((preserve_access_index)), apply_to = record)\n");
 	printf("#endif\n\n");
@@ -412,6 +415,8 @@ static int dump_btf_c(const struct btf *
 	printf("#ifndef BPF_NO_PRESERVE_ACCESS_INDEX\n");
 	printf("#pragma clang attribute pop\n");
 	printf("#endif\n");
+	printf("\n");
+	printf("#endif /* __VMLINUX_H__ */\n");
 
 done:
 	btf_dump__free(d);