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From:   Andrii Nakryiko <andrii.nakryiko@gmail.com>
Date:   Fri, 21 Jun 2019 12:06:10 -0700
Message-ID: <CAEf4Bzaajc27=YyMaOa8UFRz=xE7y6E+qLbPBPbvLADO2peXQg@mail.gmail.com>
Subject: Re: [selftests/bpf] 69d96519db: kernel_selftests.bpf.test_socket_cookie.fail
To:     Stanislav Fomichev <sdf@fomichev.me>
Cc:     kernel test robot <rong.a.chen@intel.com>,
        Stanislav Fomichev <sdf@google.com>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Martin Lau <kafai@fb.com>, LKML <linux-kernel@vger.kernel.org>,
        Stephen Rothwell <sfr@canb.auug.org.au>,
        bpf <bpf@vger.kernel.org>, lkp@01.org
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On Fri, Jun 21, 2019 at 9:11 AM Stanislav Fomichev <sdf@fomichev.me> wrote:
>
> On 06/21, kernel test robot wrote:
> > FYI, we noticed the following commit (built with gcc-7):
> >
> > commit: 69d96519dbf0bfa1868dc8597d4b9b2cdeb009d7 ("selftests/bpf: convert socket_cookie test to sk storage")
> > https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git master
> >
> > in testcase: kernel_selftests
> > with following parameters:
> >
> >       group: kselftests-00
> >
> > test-description: The kernel contains a set of "self tests" under the tools/testing/selftests/ directory. These are intended to be small unit tests to exercise individual code paths in the kernel.
> > test-url: https://www.kernel.org/doc/Documentation/kselftest.txt
> >
> >
> > on test machine: qemu-system-x86_64 -enable-kvm -cpu SandyBridge -smp 2 -m 4G
> >
> > caused below changes (please refer to attached dmesg/kmsg for entire log/backtrace):
> >
> >
> > If you fix the issue, kindly add following tag
> > Reported-by: kernel test robot <rong.a.chen@intel.com>
> >
> > # selftests: bpf: test_socket_cookie
> > # libbpf: failed to create map (name: 'socket_cookies'): Invalid
> > # argument
> Another case of old clang trying to create a map that depends on BTF?
> Should we maybe switch those BTF checks in the kernel to return
> EOPNOTSUPP to make it easy to diagnose?

For older compilers that don't generate DATASEC/VAR, you'll see a clear message:

libbpf: DATASEC '.maps' not found.

So this must be something else. I just confirmed with clang version
7.0.20180201 that for ./test_socket_cookie that's the first line
that's emitted on failure.

>
> > # libbpf: failed to load object './socket_cookie_prog.o'
> > # (test_socket_cookie.c:149: errno: Invalid argument) Failed to load
> > # ./socket_cookie_prog.o
> > # FAILED
> > not ok 15 selftests: bpf: test_socket_cookie
> >
> >
> >
> >
> > To reproduce:
> >
> >         # build kernel
> >       cd linux
> >       cp config-5.2.0-rc2-00598-g69d9651 .config
> >       make HOSTCC=gcc-7 CC=gcc-7 ARCH=x86_64 olddefconfig
> >       make HOSTCC=gcc-7 CC=gcc-7 ARCH=x86_64 prepare
> >       make HOSTCC=gcc-7 CC=gcc-7 ARCH=x86_64 modules_prepare
> >       make HOSTCC=gcc-7 CC=gcc-7 ARCH=x86_64 SHELL=/bin/bash
> >       make HOSTCC=gcc-7 CC=gcc-7 ARCH=x86_64 bzImage
> >
> >
> >         git clone https://github.com/intel/lkp-tests.git
> >         cd lkp-tests
> >         bin/lkp qemu -k <bzImage> job-script # job-script is attached in this email
> >
> >
> >
> > Thanks,
> > Rong Chen
> >
>

<mega snip>