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From: Yonghong Song <yhs@fb.com>
To: Shuah Khan <skhan@linuxfoundation.org>,
	Alexei Starovoitov <alexei.starovoitov@gmail.com>,
	Daniel Borkmann <daniel@iogearbox.net>
Cc: "open list:KERNEL SELFTEST FRAMEWORK" 
	<linux-kselftest@vger.kernel.org>, bpf <bpf@vger.kernel.org>,
	Networking <netdev@vger.kernel.org>,
	"David S. Miller" <davem@davemloft.net>,
	Andrii Nakryiko <andriin@fb.com>
Subject: Re: Linux 5.4 - bpf test build fails
Date: Tue, 24 Sep 2019 15:43:54 +0000	[thread overview]
Message-ID: <0a5bf608-bb15-c116-8e58-7224b6c3b62f@fb.com> (raw)
In-Reply-To: <742ecabe-45ce-cf6e-2540-25d6dc23c45f@linuxfoundation.org>



On 9/24/19 8:26 AM, Shuah Khan wrote:
> Hi Alexei and Daniel,
> 
> bpf test doesn't build on Linux 5.4 mainline. Do you know what's
> happening here.
> 
> 
> make -C tools/testing/selftests/bpf/
> 
> -c progs/test_core_reloc_ptr_as_arr.c -o - || echo "clang failed") | \
> llc -march=bpf -mcpu=generic  -filetype=obj -o 
> /mnt/data/lkml/linux_5.4/tools/testing/selftests/bpf/test_core_reloc_ptr_as_arr.o 
> 
> progs/test_core_reloc_ptr_as_arr.c:25:6: error: use of unknown builtin
>        '__builtin_preserve_access_index' [-Wimplicit-function-declaration]
>          if (BPF_CORE_READ(&out->a, &in[2].a))
>              ^
> ./bpf_helpers.h:533:10: note: expanded from macro 'BPF_CORE_READ'
>                         __builtin_preserve_access_index(src))
>                         ^
> progs/test_core_reloc_ptr_as_arr.c:25:6: warning: incompatible integer to
>        pointer conversion passing 'int' to parameter of type 'const void *'
>        [-Wint-conversion]
>          if (BPF_CORE_READ(&out->a, &in[2].a))
>              ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> ./bpf_helpers.h:533:10: note: expanded from macro 'BPF_CORE_READ'
>                         __builtin_preserve_access_index(src))
>                         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 1 warning and 1 error generated.
> llc: error: llc: <stdin>:1:1: error: expected top-level entity
> clang failed
> 
> Also
> 
> make TARGETS=bpf kselftest fails as well. Dependency between
> tools/lib/bpf and the test. How can we avoid this type of
> dependency or resolve it in a way it doesn't result in build
> failures?

Thanks, Shuah.

The clang __builtin_preserve_access_index() intrinsic is
introduced in LLVM9 (which just released last week) and
the builtin and other CO-RE features are only supported
in LLVM10 (current development branch) with more bug fixes
and added features.

I think we should do a feature test for llvm version and only
enable these tests when llvm version >= 10.

Andrii, what do you think?

> 
> thanks,
> -- Shuah

  reply	other threads:[~2019-09-24 15:44 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-24 15:26 Linux 5.4 - bpf test build fails Shuah Khan
2019-09-24 15:43 ` Yonghong Song [this message]
2019-09-24 15:48   ` Shuah Khan
2019-09-24 18:49     ` Daniel Borkmann
2019-09-24 18:56       ` Shuah Khan
2019-09-24 19:19         ` Daniel Borkmann
2019-09-24 19:48           ` Shuah Khan
2019-09-24 15:52 ` Cristian Marussi
2019-09-24 16:03   ` Shuah Khan
2019-09-24 16:39     ` Shuah Khan
2019-09-24 17:29       ` Cristian Marussi
2019-09-24 18:07         ` Tim.Bird
2019-09-24 18:23           ` Shuah Khan
2019-09-25  8:52             ` Cristian Marussi

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