bpf: Fix build in minimal configurations, again

Building with -Werror showed another failure:

kernel/bpf/btf.c: In function 'btf_get_prog_ctx_type.isra.31':
kernel/bpf/btf.c:3508:63: error: array subscript 0 is above array bounds of 'u8[0]' {aka 'unsigned char[0]'} [-Werror=array-bounds]
  ctx_type = btf_type_member(conv_struct) + bpf_ctx_convert_map[prog_type] * 2;

I don't actually understand why the array is empty, but a similar
fix has addressed a related problem, so I suppose we can do the
same thing here.

Fixes: ce27709b8162 ("bpf: Fix build in minimal configurations")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20191210203553.2941035-1-arnd@arndb.de

diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 7d40da240891d3b0885ad97d1c43b0fa50611081..ed20758847247c988c41cbd5610368160b22b358 100644 (file)
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -3470,6 +3470,7 @@ static u8 bpf_ctx_convert_map[] = {
        [_id] = __ctx_convert##_id,
 #include <linux/bpf_types.h>
 #undef BPF_PROG_TYPE
+       0, /* avoid empty array */
 };
 #undef BPF_MAP_TYPE