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Date: Wed, 21 Feb 2024 14:01:09 -0800
From: Kees Cook <keescook@chromium.org>
To: Daniel Borkmann <daniel@iogearbox.net>
Cc: Mark Rutland <mark.rutland@arm.com>,
	"Gustavo A . R . Silva" <gustavoars@kernel.org>,
	Alexei Starovoitov <ast@kernel.org>,
	Andrii Nakryiko <andrii@kernel.org>,
	Martin KaFai Lau <martin.lau@linux.dev>, Song Liu <song@kernel.org>,
	Yonghong Song <yhs@fb.com>,
	John Fastabend <john.fastabend@gmail.com>,
	KP Singh <kpsingh@kernel.org>, Stanislav Fomichev <sdf@google.com>,
	Hao Luo <haoluo@google.com>, Jiri Olsa <jolsa@kernel.org>,
	Mykola Lysenko <mykolal@fb.com>, Shuah Khan <shuah@kernel.org>,
	Haowen Bai <baihaowen@meizu.com>, bpf@vger.kernel.org,
	linux-kselftest@vger.kernel.org,
	Yonghong Song <yonghong.song@linux.dev>,
	Jonathan Corbet <corbet@lwn.net>,
	"David S. Miller" <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>,
	Jesper Dangaard Brouer <hawk@kernel.org>,
	Joanne Koong <joannelkoong@gmail.com>,
	Yafang Shao <laoar.shao@gmail.com>, Kui-Feng Lee <kuifeng@meta.com>,
	Anton Protopopov <aspsk@isovalent.com>,
	linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org,
	netdev@vger.kernel.org, linux-hardening@vger.kernel.org
Subject: Re: [PATCH v4] bpf: Replace bpf_lpm_trie_key 0-length array with
 flexible array
Message-ID: <202402211347.2AF2EC4621@keescook>
References: <20240220185421.it.949-kees@kernel.org>
 <da75b2bf-0d14-6ed5-91c2-dfeba9ad55c4@iogearbox.net>
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In-Reply-To: <da75b2bf-0d14-6ed5-91c2-dfeba9ad55c4@iogearbox.net>

On Wed, Feb 21, 2024 at 05:39:55PM +0100, Daniel Borkmann wrote:
> The build in BPF CI is still broken, did you try to build selftests?

Okay, I give up. How is a mortal supposed to build these?

If I try to follow what I see in
https://github.com/libbpf/ci/blob/main/build-selftests/build_selftests.sh
I just get more and more kinds of errors:

In file included from progs/cb_refs.c:5:
progs/../bpf_testmod/bpf_testmod_kfunc.h:29:8: error: redefinition of 'prog_test_pass1'
   29 | struct prog_test_pass1 {
      |        ^
/srv/code/tools/testing/selftests/bpf/tools/include/vmlinux.h:106850:8: note: previous definition is
 here
 106850 | struct prog_test_pass1 {
        |        ^

Messing around with deleting vmlinux.h seems to get me further, but later:

/srv/code/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c: In function 'bpf_testmod_ops_is_valid_access':
/srv/code/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c:535:16: error: implicit declaration of function 'bpf_tracing_btf_ctx_access' [-Werror=implicit-function-declaration]
  535 |         return bpf_tracing_btf_ctx_access(off, size, type, prog, info);
      |                ^~~~~~~~~~~~~~~~~~~~~~~~~~

and then I'm stuck. It looks like the build isn't actually using
KBUILD_OUTPUT for finding includes. If I try to add -I flags to the
Makefile I just drown in new errors.

-- 
Kees Cook