netdev - Re: FAILED unresolved symbol vfs_truncate on arm64 with LLVM

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Message-ID: <20210209052311.GA125918@ubuntu-m3-large-x86>
Date:   Mon, 8 Feb 2021 22:23:11 -0700
From:   Nathan Chancellor <nathan@...nel.org>
To:     Andrii Nakryiko <andrii.nakryiko@...il.com>
Cc:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Networking <netdev@...r.kernel.org>, bpf <bpf@...r.kernel.org>,
        clang-built-linux <clang-built-linux@...glegroups.com>,
        Veronika Kabatova <vkabatov@...hat.com>,
        Jiri Olsa <jolsa@...nel.org>
Subject: Re: FAILED unresolved symbol vfs_truncate on arm64 with LLVM

On Mon, Feb 08, 2021 at 08:45:43PM -0800, Andrii Nakryiko wrote:
> On Mon, Feb 8, 2021 at 7:44 PM Nathan Chancellor <nathan@...nel.org> wrote:
> >
> > Hi all,
> >
> > Recently, an issue with CONFIG_DEBUG_INFO_BTF was reported for arm64:
> > https://groups.google.com/g/clang-built-linux/c/de_mNh23FOc/m/E7cu5BwbBAAJ
> >
> > $ make -skj"$(nproc)" ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- \
> >                       LLVM=1 O=build/aarch64 defconfig
> >
> > $ scripts/config \
> >     --file build/aarch64/.config \
> >     -e BPF_SYSCALL \
> >     -e DEBUG_INFO_BTF \
> >     -e FTRACE \
> >     -e FUNCTION_TRACER
> >
> > $ make -skj"$(nproc)" ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- \
> >                       LLVM=1 O=build/aarch64 olddefconfig all
> > ...
> > FAILED unresolved symbol vfs_truncate
> > ...
> >
> > My bisect landed on commit 6e22ab9da793 ("bpf: Add d_path helper")
> > although that seems obvious given that is what introduced
> > BTF_ID(func, vfs_truncate).
> >
> > I am using the latest pahole v1.20 and LLVM is at
> > https://github.com/llvm/llvm-project/commit/14da287e18846ea86e45b421dc47f78ecc5aa7cb
> > although I can reproduce back to LLVM 10.0.1, which is the earliest
> > version that the kernel supports. I am very unfamiliar with BPF so I
> > have no idea what is going wrong here. Is this a known issue?
> >
> 
> I'll skip the reproduction games this time and will just request the
> vmlinux image. Please upload somewhere so that we can look at DWARF
> and see what's going on. Thanks.
> 

Sure thing, let me know if this works. I uploaded in two places to make
it easier to grab:

zstd compressed:
https://github.com/nathanchance/bug-files/blob/3b2873751e29311e084ae2c71604a1963f5e1a48/btf-aarch64/vmlinux.zst

uncompressed:
https://1drv.ms/u/s!AsQNYeB-IEbqjQiUOspbEdXx49o7?e=ipA9Hv

Cheers,
Nathan