Re: Kernel build fail with 'btf_encoder__encode: btf__dedup failed!'

[Alexandre Peixoto Ferreira <alexandref75@gmail.com>]

Jirka and Daniel,

On 1/27/23 18:00, Jiri Olsa wrote:
> On Fri, Jan 27, 2023 at 04:28:54PM -0600, Alexandre Peixoto Ferreira wrote:
>>
>> On 1/24/23 00:13, Daniel Xu wrote:
>>> Hi Jiri,
>>>
>>> On Mon, Jan 23, 2023, at 1:06 AM, Jiri Olsa wrote:
>>>> On Sun, Jan 22, 2023 at 10:48:44AM -0700, Daniel Xu wrote:
>>>>> Hi,
>>>>>
>>>>> I'm getting the following error during build:
>>>>>
>>>>>           $ ./tools/testing/selftests/bpf/vmtest.sh -j30
>>>>>           [...]
>>>>>             BTF     .btf.vmlinux.bin.o
>>>>>           btf_encoder__encode: btf__dedup failed!
>>>>>           Failed to encode BTF
>>>>>             LD      .tmp_vmlinux.kallsyms1
>>>>>             NM      .tmp_vmlinux.kallsyms1.syms
>>>>>             KSYMS   .tmp_vmlinux.kallsyms1.S
>>>>>             AS      .tmp_vmlinux.kallsyms1.S
>>>>>             LD      .tmp_vmlinux.kallsyms2
>>>>>             NM      .tmp_vmlinux.kallsyms2.syms
>>>>>             KSYMS   .tmp_vmlinux.kallsyms2.S
>>>>>             AS      .tmp_vmlinux.kallsyms2.S
>>>>>             LD      .tmp_vmlinux.kallsyms3
>>>>>             NM      .tmp_vmlinux.kallsyms3.syms
>>>>>             KSYMS   .tmp_vmlinux.kallsyms3.S
>>>>>             AS      .tmp_vmlinux.kallsyms3.S
>>>>>             LD      vmlinux
>>>>>             BTFIDS  vmlinux
>>>>>           FAILED: load BTF from vmlinux: No such file or directory
>>>>>           make[1]: *** [scripts/Makefile.vmlinux:35: vmlinux] Error 255
>>>>>           make[1]: *** Deleting file 'vmlinux'
>>>>>           make: *** [Makefile:1264: vmlinux] Error 2
>>>>>
>>>>> This happens on both bpf-next/master (84150795a49) and 6.2-rc5
>>>>> (2241ab53cb).
>>>>>
>>>>> I've also tried arch linux pahole 1:1.24+r29+g02d67c5-1 as well as
>>>>> upstream pahole on master (02d67c5176) and upstream pahole on
>>>>> next (2ca56f4c6f659).
>>>>>
>>>>> Of the above 6 combinations, I think I've tried all of them (maybe
>>>>> missing 1 or 2).
>>>>>
>>>>> Looks like GCC got updated recently on my machine, so perhaps
>>>>> it's related?
>>>>>
>>>>>           CONFIG_CC_VERSION_TEXT="gcc (GCC) 12.2.1 20230111"
>>>>>
>>>>> I'll try some debugging, but just wanted to report it first.
>>>> hi,
>>>> I can't reproduce that.. can you reproduce it outside vmtest.sh?
>>>>
>>>> there will be lot of output with patch below, but could contain
>>>> some more error output
>>> Thanks for the hints. Doing a regular build outside of vmtest.sh
>>> seems to work ok. So maybe it's a difference in the build config.
>>>
>>> I'll put a little more time into debugging to see if it goes anywhere.
>>> But I'll have to get back to the regularly scheduled programming
>>> soon.
>> 6.2-rc5 compiles correctly when CONFIG_X86_KERNEL_IBT is commented but fails
>> in pahole when CONFIG_X86_KERNEL_IBT is set.
> could you plese attach your config and the build error?
> I can't reproduce that
>
> thanks,
> jirka

My working .config is available at https://pastebin.pl/view/bef3765c
change CONFIG_X86_KERNEL_IBT to y to get the error.

The error is similar to Daniel's and is shown below:

   LD      .tmp_vmlinux.btf
   BTF     .btf.vmlinux.bin.o
btf_encoder__encode: btf__dedup failed!
Failed to encode BTF
   LD      .tmp_vmlinux.kallsyms1
   NM      .tmp_vmlinux.kallsyms1.syms
   KSYMS   .tmp_vmlinux.kallsyms1.S
   AS      .tmp_vmlinux.kallsyms1.S
   LD      .tmp_vmlinux.kallsyms2
   NM      .tmp_vmlinux.kallsyms2.syms
   KSYMS   .tmp_vmlinux.kallsyms2.S
   AS      .tmp_vmlinux.kallsyms2.S
   LD      .tmp_vmlinux.kallsyms3
   NM      .tmp_vmlinux.kallsyms3.syms
   KSYMS   .tmp_vmlinux.kallsyms3.S
   AS      .tmp_vmlinux.kallsyms3.S
   LD      vmlinux
   BTFIDS  vmlinux
FAILED: load BTF from vmlinux: No such file or directory
make[1]: *** [scripts/Makefile.vmlinux:35: vmlinux] Error 255
make[1]: *** Deleting file 'vmlinux'
make: *** [Makefile:1264: vmlinux] Error 2


Thanks,

-- 
Alexandre Peixoto Ferreira