On 11/29/19 8:30 AM, Eelco Chaudron wrote:
>
>
> On 28 Nov 2019, at 20:47, Alexei Starovoitov wrote:
>
>> On Thu, Nov 28, 2019 at 11:16 AM Eelco Chaudron <echaudro@xxxxxxxxxx>
>> wrote:
>>>
>>>
>>>
>>> On 28 Nov 2019, at 19:18, Alexei Starovoitov wrote:
>>>
>>>> On Thu, Nov 28, 2019 at 9:20 AM Eelco Chaudron <echaudro@xxxxxxxxxx>
>>>> wrote:
>>>>>
>>>>> Trying out the BPF trace to trace a BPF program, but I’m already
>>>>> getting stuck loading the object with the fexit :(
>>>>
>>>> I can take a look after holidays.
>>>
>>> Enjoy the Holidays!! I figured out my auto kernel install script failed
>>> whiteout me noticing, and I was running an old kernel :(
>>>
>>> I will try tomorrow with the correct kernel…
>>
>> Please also check that you have the latest llvm and pahole.
>> pahole version should be >= 1.13.
>> clang ideally from master.
>> If all that is working then downgrade one by one and bisect whether
>> the bug is.
>>
>
> I tried it with the latest kernel loaded but still I got some errors on
> bpf_object__load_xattr():
>
> $ sudo ./xdp_sample_fentry_fexit_user
> libbpf: Cannot find bpf_func_info for main program sec
> fexit/xdp_prog_simple. Ignore all bpf_func_info.
> libbpf: load bpf program failed: Operation not permitted
> libbpf: failed to load program 'fexit/xdp_prog_simple'
> libbpf: failed to load object './xdp_sample_fentry_fexit_kern.o'
> ERROR: Failed to load object file: Operation not permitted
>
>
> With strace:
>
> [vagrant@xdp-tutorial tracing05-xdp-fentry]$ sudo
> /home/vagrant/strace/strace -e bpf ./xdp_sample_fentry_fexit_user
> bpf(BPF_PROG_GET_FD_BY_ID, {prog_id=36, next_id=0, open_flags=0}, 120) = 3
> bpf(BPF_PROG_LOAD, {prog_type=BPF_PROG_TYPE_SOCKET_FILTER, insn_cnt=2,
> insns=0x7ffcaedfd4f0, license="GPL", log_level=0, log_size=0,
> log_buf=NULL, kern_version=KERNEL_VERSION(0, 0, 0), prog_flags=0,
> prog_name="", prog_ifindex=0,
> expected_attach_type=BPF_CGROUP_INET_INGRESS, prog_btf_fd=0,
> func_info_rec_size=0, func_info=NULL, func_info_cnt=0,
> line_info_rec_size=0, line_info=NULL, line_info_cnt=0}, 120) = 5
> bpf(BPF_PROG_LOAD, {prog_type=BPF_PROG_TYPE_SOCKET_FILTER, insn_cnt=2,
> insns=0x7ffcaedfd4f0, license="GPL", log_level=0, log_size=0,
> log_buf=NULL, kern_version=KERNEL_VERSION(0, 0, 0), prog_flags=0,
> prog_name="test", prog_ifindex=0,
> expected_attach_type=BPF_CGROUP_INET_INGRESS, prog_btf_fd=0,
> func_info_rec_size=0, func_info=NULL, func_info_cnt=0,
> line_info_rec_size=0, line_info=NULL, line_info_cnt=0}, 120) = 5
> bpf(BPF_MAP_CREATE, {map_type=BPF_MAP_TYPE_ARRAY, key_size=4,
> value_size=32, max_entries=1, map_flags=0, inner_map_fd=0, map_name="",
> map_ifindex=0, btf_fd=0, btf_key_type_id=0, btf_value_type_id=0}, 120) = 5
> bpf(BPF_PROG_LOAD, {prog_type=BPF_PROG_TYPE_SOCKET_FILTER, insn_cnt=5,
> insns=0x7ffcaedfd490, license="GPL", log_level=0, log_size=0,
> log_buf=NULL, kern_version=KERNEL_VERSION(0, 0, 0), prog_flags=0,
> prog_name="", prog_ifindex=0,
> expected_attach_type=BPF_CGROUP_INET_INGRESS, prog_btf_fd=0,
> func_info_rec_size=0, func_info=NULL, func_info_cnt=0,
> line_info_rec_size=0, line_info=NULL, line_info_cnt=0}, 120) = 6
> bpf(BPF_BTF_LOAD,
> {btf="\237\353\1\0\30\0\0\0\0\0\0\0000\0\0\0000\0\0\0\t\0\0\0\1\0\0\0\0\0\0\1"...,
> btf_log_buf=NULL, btf_size=81, btf_log_size=0, btf_log_level=0}, 120) = 5
> bpf(BPF_BTF_LOAD,
> {btf="\237\353\1\0\30\0\0\0\0\0\0\08\0\0\08\0\0\0\t\0\0\0\0\0\0\0\0\0\0\1"...,
> btf_log_buf=NULL, btf_size=89, btf_log_size=0, btf_log_level=0}, 120) = 5
> bpf(BPF_MAP_CREATE, {map_type=BPF_MAP_TYPE_ARRAY, key_size=4,
> value_size=4, max_entries=1, map_flags=0x400 /* BPF_F_??? */,
> inner_map_fd=0, map_name="", map_ifindex=0, btf_fd=0, btf_key_type_id=0,
> btf_value_type_id=0}, 120) = -1 EPERM (Operation not permitted)
> bpf(BPF_BTF_LOAD,
> {btf="\237\353\1\0\30\0\0\0\0\0\0\0`\1\0\0`\1\0\0\236\0\0\0\0\0\0\0\0\0\0\3"...,
> btf_log_buf=NULL, btf_size=534, btf_log_size=0, btf_log_level=0}, 120) = 5
> bpf(BPF_OBJ_GET_INFO_BY_FD, {info={bpf_fd=3, info_len=208,
> info=0x7ffcaedfd4a0}}, 120) = 0
> bpf(BPF_OBJ_GET_INFO_BY_FD, {info={bpf_fd=3, info_len=208,
> info=0x2018c30}}, 120) = 0
> bpf(BPF_BTF_GET_FD_BY_ID, {btf_id=3}, 120) = 4
> bpf(BPF_OBJ_GET_INFO_BY_FD, {info={bpf_fd=4, info_len=16,
> info=0x7ffcaedfd5a0}}, 120) = 0
> libbpf: Cannot find bpf_func_info for main program sec
> fexit/xdp_prog_simple. Ignore all bpf_func_info.
> bpf(BPF_PROG_LOAD, {prog_type=0x1a /* BPF_PROG_TYPE_??? */, insn_cnt=30,
> insns=0x20191f0, license="GPL", log_level=7, log_size=16777215,
> log_buf="", kern_version=KERNEL_VERSION(0, 0, 0), prog_flags=0,
> prog_name="trace_on_exit", prog_ifindex=0, expected_attach_type=0x19 /*
> BPF_??? */, prog_btf_fd=5, func_info_rec_size=0, func_info=NULL,
> func_info_cnt=0, line_info_rec_size=0, line_info=NULL, line_info_cnt=0,
> ...}, 120) = -1 EPERM (Operation not permitted)
> libbpf: load bpf program failed: Operation not permitted
> libbpf: failed to load program 'fexit/xdp_prog_simple'
> libbpf: failed to load object './xdp_sample_fentry_fexit_kern.o'
> ERROR: Failed to load object file: Operation not permitted
> +++ exited with 0 +++
>
> And with full libbpf print debugging:
>
> libbpf: loading ./xdp_sample_fentry_fexit_kern.o
> libbpf: section(1) .strtab, size 250, link 0, flags 0, type=3
> libbpf: skip section(1) .strtab
> libbpf: section(2) .text, size 0, link 0, flags 6, type=1
> libbpf: skip section(2) .text
> libbpf: section(3) fexit/xdp_prog_simple, size 240, link 0, flags 6, type=1
> libbpf: found program fexit/xdp_prog_simple
> libbpf: section(4) license, size 4, link 0, flags 3, type=1
> libbpf: license of ./xdp_sample_fentry_fexit_kern.o is GPL
> libbpf: section(5) .rodata.str1.1, size 52, link 0, flags 32, type=1
> libbpf: skip section(5) .rodata.str1.1
> libbpf: section(6) .debug_str, size 344, link 0, flags 30, type=1
> libbpf: skip section(6) .debug_str
> libbpf: section(7) .debug_loc, size 70, link 0, flags 0, type=1
> libbpf: skip section(7) .debug_loc
> libbpf: section(8) .debug_abbrev, size 297, link 0, flags 0, type=1
> libbpf: skip section(8) .debug_abbrev
> libbpf: section(9) .debug_info, size 403, link 0, flags 0, type=1
> libbpf: skip section(9) .debug_info
> libbpf: section(10) .rel.debug_info, size 528, link 21, flags 0, type=9
> libbpf: skip relo .rel.debug_info(10) for section(9)
> libbpf: section(11) .debug_ranges, size 96, link 0, flags 0, type=1
> libbpf: skip section(11) .debug_ranges
> libbpf: section(12) .debug_macinfo, size 1, link 0, flags 0, type=1
> libbpf: skip section(12) .debug_macinfo
> libbpf: section(13) .BTF, size 534, link 0, flags 0, type=1
> libbpf: section(14) .rel.BTF, size 16, link 21, flags 0, type=9
> libbpf: skip relo .rel.BTF(14) for section(13)
> libbpf: section(15) .BTF.ext, size 152, link 0, flags 0, type=1
> libbpf: section(16) .rel.BTF.ext, size 96, link 21, flags 0, type=9
> libbpf: skip relo .rel.BTF.ext(16) for section(15)
> libbpf: section(17) .debug_frame, size 40, link 0, flags 0, type=1
> libbpf: skip section(17) .debug_frame
> libbpf: section(18) .rel.debug_frame, size 32, link 21, flags 0, type=9
> libbpf: skip relo .rel.debug_frame(18) for section(17)
> libbpf: section(19) .debug_line, size 206, link 0, flags 0, type=1
> libbpf: skip section(19) .debug_line
> libbpf: section(20) .rel.debug_line, size 16, link 21, flags 0, type=9
> libbpf: skip relo .rel.debug_line(20) for section(19)
> libbpf: section(21) .symtab, size 792, link 1, flags 0, type=2
> libbpf: Cannot find bpf_func_info for main program sec
> fexit/xdp_prog_simple. Ignore all bpf_func_info.
> libbpf: load bpf program failed: Operation not permitted
> libbpf: failed to load program 'fexit/xdp_prog_simple'
> libbpf: failed to load object './xdp_sample_fentry_fexit_kern.o'
> ERROR: Failed to load object file: Operation not permitted
>
> I’m using the latest pahole, but standard llvm 9.0.0 from Fedora.
>
> So I decided to at least run the self-test and see if this passes, and
> work my way from there.
> But it’s failing to build with errors like “use of unknown builtin
> '__builtin_preserve_field_info’”, so I’m assuming my clang9 needs
> upgrading…
Yes, please try latest llvm trunk. You can find the information on the
web. Below is the instruction from iovisor/bcc repo.
(https://github.com/iovisor/bcc/blob/master/INSTALL.md#older-instructions)
git clone https://github.com/llvm/llvm-project.git
mkdir -p llvm-project/llvm/build/install
cd llvm-project/llvm/build
cmake -G "Ninja" -DLLVM_TARGETS_TO_BUILD="BPF;X86" \
-DLLVM_ENABLE_PROJECTS="clang" \
-DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=$PWD/install ..
ninja && ninja install
export PATH=$PWD/install/bin:$PATH
>
> I quickly tried doing this while working on other stuff, but I failed to
> multitask, so will continue with this next week.
>
> Any ideas are welcome…
>
> Cheers,
>
>
> Eelco
>
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