Re: Problem with BTF generation on mips64el

[Tony Ambardar <tony.ambardar@gmail.com>]

Hello Hengqi,

On Fri, May 31, 2024 at 10:17:53AM +0800, Hengqi Chen wrote:
> Hi Tony,
> 
> On Fri, May 31, 2024 at 9:30 AM Tony Ambardar <tony.ambardar@gmail.com> 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.
> >
> SNIP
> >
> > >   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.

Good idea. I tried rebuilding elfutils from the latest upstream commit:
https://sourceware.org/git/?p=elfutils.git;a=commit;h=935ee131cf7c87296df9412b7e3370085e7c7508

I then linked this elfutils with pahole built from the latest pahole/next:
https://git.kernel.org/pub/scm/devel/pahole/pahole.git/commit/?h=next&id=a9ae414fef421bdeb13ff7ffe13271e1e4f58993

I also confirmed resolve_btfids links to the new elfutils, and then rebuilt
the kernel with the same config. Unfortunately, the warnings/errors from
resolve_btfids and pahole still occur.

> SNIP
> >
> > 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@intel.com/ [1]
> > Link: https://github.com/acmel/dwarves/issues/45 [2]
> 
> Cheers,
> Hengqi

Thanks for the suggestion,
Tony