Re: ld.lld: error: vmlinux.a(kernel/kallsyms.o):(function kallsyms_lookup_name: .text+0x90): relocation R_RISCV_PCREL_HI20 out of range: -524416 is not in [-524288, 524287]; references kallsyms_seqs_of_names

[Leizhen (ThunderTown)]

On 2024/3/12 13:53, Yujie Liu wrote:
> Hi Zhen,
> 
> On Tue, Feb 20, 2024 at 08:27:15PM +0800, Leizhen (ThunderTown) wrote:
>>> On 2024/2/6 13:19, kernel test robot wrote:
>>>> Hi Zhen,
>>>>
>>>> FYI, the error/warning still remains.
>>>
>>> I'm trying to reproduce it. But I'm having a little trouble getting
>>> the environment ready.
>>
>> Sorry, I tried but it was not reproduced. I made the following two changes
>> to the steps in the 'reproduce' link:
>> 1. Put linux and lkp-tests in two directories of the same level. Because:
>>    $ git fetch --no-tags linus master
>>    error: RPC failed; HTTP 403 curl 22 The requested URL returned error: 403
>>    fatal: error reading section header 'acknowledgments'
>> 2. Compiler was specified by following the prompts.
>>    COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-17 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=riscv olddefconfig
>>    COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-17 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=riscv SHELL=/bin/bash
>>    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> 
> Sorry for our late reply. We rechecked this case and noticed that this
> issue can be reproduced by clang-15, but can't be reproduced by newer
> version of clang. Not sure if this is a flaw in old version of LLVM
> toolchain, just for your information.

Well, I was able to reproduce it, too, after changing to clang-15.
It should be a problem with the LLVM toolchain. After all, the Linux
source code has not changed. The problem occurs in the linking phase
of Linux, not in the execution phase of Linux. In addition to the few
symbols I added that failed to relocate, the original ones also failed
to relocate. I am not familiar with the source code of the compiler,
so I cannot further analyze the root cause.

Here is a brief description of how kallsyms works. This may help you
understand the problem.
1. Build Linux source code, generate a symbol table.
2. Run tool kallsyms to read above symbol table, rearranges symbol
   information as needed for lookup by name and lookup by address. Record
   these new information into kallsyms_seqs_of_names[], etc. Insert the new
   variables into a new C file.
3. Rebuild Linux with the new C file. The problem is at this stage, for
   those symbols added by tool kallsyms, the relocation fails.

> 
> $ COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-15 ~/lkp-tests/kbuild/make.cross W=1 ARCH=riscv
> ..
>   LD      .tmp_vmlinux.kallsyms1
> ld.lld: error: vmlinux.a(kernel/kallsyms.o):(function kallsyms_lookup_name: .text+0x70): relocation R_RISCV_PCREL_HI20 out of range: -524416 is not in [-524288, 524287]; references kallsyms_num_syms
>>>> referenced by kallsyms.c
>>>> defined in vmlinux.a(kernel/kallsyms.o)
> 
> ld.lld: error: vmlinux.a(kernel/kallsyms.o):(function kallsyms_lookup_name: .text+0x90): relocation R_RISCV_PCREL_HI20 out of range: -524416 is not in [-524288, 524287]; references kallsyms_seqs_of_names
>>>> referenced by kallsyms.c
>>>> defined in vmlinux.a(kernel/kallsyms.o)
> ..
> 
> Thanks,
> Yujie
> 
>>
>> Image is finally generated, so there should be no problem with the above steps being adjusted:
>> $ ls build_dir/arch/riscv/boot/
>> dts  Image  loader  loader.bin  loader.lds  loader.o
>>
>> By the way, all the symbols to be reported "relocation R_RISCV_PCREL_HI20 out of range" is
>> generated by the tool kallsyms (scripts/kallsyms.c). So, it seems that the tool kallsyms
>> have not been executed. And this error is not caused by my patches.
>>
>>>
>>>>
>>>> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
>>>> head:   54be6c6c5ae8e0d93a6c4641cb7528eb0b6ba478
>>>> commit: 60443c88f3a89fd303a9e8c0e84895910675c316 kallsyms: Improve the performance of kallsyms_lookup_name()
>>>> date:   1 year, 3 months ago
>>>> config: riscv-randconfig-r064-20240120 (https://download.01.org/0day-ci/archive/20240206/202402061302.HkByW9x0-lkp@xxxxxxxxx/config)
>>>> compiler: clang version 15.0.7 (https://github.com/llvm/llvm-project.git 8dfdcc7b7bf66834a761bd8de445840ef68e4d1a)
>>>> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240206/202402061302.HkByW9x0-lkp@xxxxxxxxx/reproduce)
>>>>
>>>> If you fix the issue in a separate patch/commit (i.e. not just a new version of
>>>> the same patch/commit), kindly add following tags
>>>> | Reported-by: kernel test robot <lkp@xxxxxxxxx>
>>>> | Closes: https://lore.kernel.org/oe-kbuild-all/202402061302.HkByW9x0-lkp@xxxxxxxxx/
>>>>
>>>> All errors (new ones prefixed by >>):
>>>>
>>>>>> ld.lld: error: vmlinux.a(kernel/kallsyms.o):(function kallsyms_lookup_name: .text+0x90): relocation R_RISCV_PCREL_HI20 out of range: -524416 is not in [-524288, 524287]; references kallsyms_seqs_of_names
>>>>    >>> referenced by kallsyms.c
>>>>    >>> defined in vmlinux.a(kernel/kallsyms.o)
>>>>
>>>
> 
> .
> 

-- 
Regards,
  Zhen Lei