Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Wed, 9 Dec 2020 16:23:04 -0600
From:   Seth Forshee <seth.forshee@canonical.com>
To:     Alexei Starovoitov <ast@kernel.org>
Cc:     Daniel Borkmann <daniel@iogearbox.net>,
        Andrii Nakryiko <andrii@kernel.org>,
        linux-kselftest@vger.kernel.org, netdev@vger.kernel.org,
        bpf@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: BPF selftests build failure in 5.10-rc
Message-ID: <X9FOSImMbu0/SV5B@ubuntu-x1>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
Precedence: bulk

Building the BPF selftests with clang 11, I'm getting the following
error:

   CLNG-LLC [test_maps] profiler1.o
 In file included from progs/profiler1.c:6:
 progs/profiler.inc.h:260:17: error: use of unknown builtin '__builtin_preserve_enum_value' [-Wimplicit-function-declaration]
                 int cgrp_id = bpf_core_enum_value(enum cgroup_subsys_id___local,
                               ^
 /home/ubuntu/unstable/tools/testing/selftests/bpf/tools/include/bpf/bpf_core_read.h:179:2: note: expanded from macro 'bpf_core_enum_value'
         __builtin_preserve_enum_value(*(typeof(enum_type) *)enum_value, BPF_ENUMVAL_VALUE)
         ^
 1 error generated.
 llc: error: llc: <stdin>:1:1: error: expected top-level entity
 BPF obj compilation failed

I see that test_core_reloc_enumval.c takes precautions around the use of
__builtin_preserve_enum_value as it is currently only available in clang
12 nightlies. Is it possible to do something similar here? Though I see
that the use of the builtin is not nearly so neatly localized as it is
in test_core_reloc_enumval.c.

Thanks,
Seth