Hi Tony,
On Fri, May 31, 2024 at 9:30 AM Tony Ambardar <tony.ambardar@xxxxxxxxx> wrote:
>
> Hello,
>
> For some time now I'm seeing multiple issues during BTF generation while
> building recent kernels targeting mips64el, and would appreciate some help
> to understand and fix the problems.
>
> Some relate to resolve_btfids:
>
> > LD vmlinux
> > BTFIDS vmlinux
> > WARN: resolve_btfids: unresolved symbol bpf_verify_pkcs7_signature
> > WARN: resolve_btfids: unresolved symbol bpf_session_cookie
> > WARN: resolve_btfids: unresolved symbol bpf_lookup_user_key
> > WARN: resolve_btfids: unresolved symbol bpf_lookup_system_key
> > WARN: resolve_btfids: unresolved symbol bpf_key_put
> > WARN: resolve_btfids: unresolved symbol bpf_iter_task_next
> > WARN: resolve_btfids: unresolved symbol bpf_iter_css_task_new
> > WARN: resolve_btfids: unresolved symbol bpf_get_file_xattr
> > WARN: resolve_btfids: unresolved symbol bpf_ct_insert_entry
> > WARN: resolve_btfids: unresolved symbol bpf_cgroup_release
> > WARN: resolve_btfids: unresolved symbol bpf_cgroup_from_id
> > WARN: resolve_btfids: unresolved symbol bpf_cgroup_acquire
> > WARN: resolve_btfids: unresolved symbol bpf_arena_free_pages
> > NM System.map
> > SORTTAB vmlinux
> > OBJCOPY vmlinux.32
>
> These do not appear to be #ifdef-related and have similar past reports [1].
>
> I also see many pahole failures during BTF encoding of modules, such as:
>
> > CC [M] net/ipv6/netfilter/nft_fib_ipv6.mod.o
> > CC [M] net/ipv6/netfilter/ip6t_REJECT.mod.o
> > CC [M] net/psample/psample.mod.o
> > LD [M] crypto/cmac.ko
> > BTF [M] crypto/cmac.ko
> > die__process: DW_TAG_compile_unit, DW_TAG_type_unit, DW_TAG_partial_unit
> > or DW_TAG_skeleton_unit expected got member (0xd)!
The issue seems to be related to elfutils. Have you tried build from
the latest elfutils source ?
I saw the latest MIPS backend in elfutils already implemented the
reloc_simple_type hook.
> > LD [M] lib/test_bpf.ko
> > BTF [M] lib/test_bpf.ko
> > die__process: DW_TAG_compile_unit, DW_TAG_type_unit, DW_TAG_partial_unit
> > or DW_TAG_skeleton_unit expected got member (0xd)!
> > LD [M] lib/crc-ccitt.ko
> > BTF [M] lib/crc-ccitt.ko
> > die__process_unit: DW_TAG_compile_unit (0x11) @ <0x9331> not handled!
> > die__process_unit: tag not supported 0x11 (compile_unit)!
> > die__process: got compile_unit unexpected tag after DW_TAG_compile_unit!
> > LD [M] lib/libcrc32c.ko
> > BTF [M] lib/libcrc32c.ko
> > die__process_unit: DW_TAG_compile_unit (0x11) @ <0x99a5> not handled!
> > die__process_unit: tag not supported 0x11 (compile_unit)!
> > die__process: got compile_unit unexpected tag after DW_TAG_compile_unit!
> > LD [M] lib/ts_kmp.ko
> > BTF [M] lib/ts_kmp.ko
> > LD [M] lib/ts_bm.ko
> > BTF [M] lib/ts_bm.ko
> > die__process: DW_TAG_compile_unit, DW_TAG_type_unit, DW_TAG_partial_unit
> > or DW_TAG_skeleton_unit expected got member (0xd)!
> > die__process: DW_TAG_compile_unit, DW_TAG_type_unit, DW_TAG_partial_unit
> > or DW_TAG_skeleton_unit expected got member (0xd)!
>
> I have seen reports of various similar "die__" messages on the dwarves
> list and repo, with the hint of an elfutils connection [2] but nothing
> conclusive.
>
> Details of the git commit and build environment are as follows:
>
> > $ git log -1 --oneline bpf/master
> > 9dfdb706e164 (bpf/master) selftests/bpf: fix inet_csk_accept prototype in
> > test_sk_storage_tracing.c
> >
> > $ lsb_release -a
> > Description: Ubuntu 22.04.4 LTS
> >
> > $ cat gcc-compile.txt
> > ARCH=mips CROSS_COMPILE=mips64el-linux-gnuabi64- CC="ccache ${CROSS_COMPILE}gcc" make -j6
> >
> > $ mips64el-linux-gnuabi64-gcc --version
> > mips64el-linux-gnuabi64-gcc (Ubuntu 10.3.0-1ubuntu1) 10.3.0
> >
> > $ mips64el-linux-gnuabi64-ld --version
> > GNU ld (GNU Binutils for Ubuntu) 2.38
> >
> > $ pahole --version
> > v1.26
> >
> > $ ldd $(which pahole)
> > linux-vdso.so.1 (0x00007fff16f3f000)
> > libdw.so.1 => /lib/x86_64-linux-gnu/libdw.so.1 (0x00007fc39d42e000)
> > libelf.so.1 => /lib/x86_64-linux-gnu/libelf.so.1 (0x00007fc39d410000)
> > libz.so.1 => /lib/x86_64-linux-gnu/libz.so.1 (0x00007fc39d3f4000)
> > libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007fc39d1cb000)
> > liblzma.so.5 => /lib/x86_64-linux-gnu/liblzma.so.5 (0x00007fc39d1a0000)
> > libbz2.so.1.0 => /lib/x86_64-linux-gnu/libbz2.so.1.0 (0x00007fc39d18d000)
> > /lib64/ld-linux-x86-64.so.2 (0x00007fc39d59d000)
> >
> > $ dpkg -s elfutils
> > Package: elfutils
> > ...
> > Version: 0.186-1build1
> > Depends: libasm1 (>= 0.132), libc6 (>= 2.34), libdw1 (= 0.186-1build1),
> > libelf1 (= 0.186-1build1), libstdc++6 (>= 4.1.1)
>
> For reference, I also attached the full .config and build log from the
> above.
>
> I should add this is not only a problem with the latest bpf/master but
> also appears to affect the 6.6.x LTS kernel, which I tested while building
> a mips64el OpenWrt distro image. That build environment employs the latest
> gcc 13.3, binutils 2.42, pahole 1.26, and elfutils 0.191.
>
> Not only do I see similar warnings from resolve_btfids and pahole, but
> while running the distro image I encounter module loading failures that
> suggest ELF corruption in some module .ko files, based on the following:
>
> > root@OpenWrt:/# strace insmod /lib/modules/6.6.30/nf_conntrack.ko
> > ...
> > init_module(0xfff3e36160, 307448, "") = -1 EINVAL (Invalid argument)
> > ...
>
> > $ man init_module
> > ...
> > The following errors may additionally occur for init_module():
> > ...
> > EINVAL param_values is invalid, or some part of the ELF image in
> > module_image contains inconsistencies.
> > ...
>
> I'd be grateful if some of the BTF/pahole experts could please review this
> issue and share next steps or other details I might provide.
>
> Thanks,
> Tony Ambardar
>
> Link: https://lore.kernel.org/all/202401211357.OCX9yllM-lkp@xxxxxxxxx/ [1]
> Link: https://github.com/acmel/dwarves/issues/45 [2]
Cheers,
Hengqi
