Re: dwarf_nextcu can't handle abbrev offset correctly ?

[Mark Wielaard <mark@klomp.org>]

Hi Hengqi,

On Thu, 2022-12-01 at 23:34 +0800, Hengqi Chen via Elfutils-devel
wrote:
> I am using pahole (which relies on libelf) to process an elf file
> ([0]):
> 
>     LLVM_OBJCOPY="objcopy" pahole -J --btf_gen_floats --btf_base
> vmlinux adl_pci9111.ko
> 
> This failed with:
> 
>     die__process: DW_TAG_compile_unit, DW_TAG_type_unit,
> DW_TAG_partial_unit or DW_TAG_skeleton_unit expected got member
> (0xd)!
> 
> The .ko contains two CU, readelf says that the abbrev offsets are at
> 0 and 0x907,
> but dwarf_nextcu reports that abbrev offsets are both at 0.
> 
> pahole expects to find DW_TAG_compile_unit, but seams that the wrong
> abbrev offset causes the failure.
> 
> 
>   [0]: https://gitlab.com/chenhengqi/loong-debug

I took a quick look at the adl_pci9111.ko there. And the issue is that
elfutils doesn't know how to handle the relocations for LoongArch yet.

Specifically the backend should implement the reloc_simple_type hook.

Cheers,

Mark