Compile error ppc64le: Cannot find symbol for section 11: .text.unlikely.

[Veronika Kabatova]

On Wed, Dec 1, 2021 at 3:20 AM Coiby Xu <coxu at redhat.com> wrote:
>
> On Wed, Nov 24, 2021 at 09:47:43PM +0800, Baoquan He wrote:
> >On 11/24/21 at 01:47pm, Veronika Kabatova wrote:
> >> Hi,
> >>
> >> for a while we've been seen the following error when compiling
> >> the mainline kernel with gcc 11.2 and binutils 2.37:
> >>
> >> 00:02:32 Cannot find symbol for section 11: .text.unlikely.
> >> 00:02:32 kernel/kexec_file.o: failed
> >> 00:02:32 make[3]: *** [scripts/Makefile.build:287: kernel/kexec_file.o] Error 1
> >> 00:02:32 make[3]: *** Deleting file 'kernel/kexec_file.o'
> >> 00:02:32 make[2]: *** [Makefile:1846: kernel] Error 2
> >> 00:02:32 make[2]: *** Waiting for unfinished jobs....
> >>
> >> The error only happens with ppc64le. I've tested this with cross
> >> compilation, but the only reference to the error I found suggests
> >> the same happens with the native compiles as well:
> >>
> >> https://github.com/groeck/linux-build-test/commit/142cbefbc0d37962c9a6c7f28ee415ecd5fd1e98
> >>
> >> In case it matters, the config used is the Fedora config with
> >> kselftest options enabled, which you can grab from
> >>
> >> https://gitlab.com/redhat/red-hat-ci-tools/kernel/cki-internal-pipelines/cki-trusted-contributors/-/jobs/1760752896/artifacts/raw/artifacts/kernel-mainline.kernel.org-ppc64le-e4e737bb5c170df6135a127739a9e6148ee3da82.config
> >>
> >>
> >> I've reached out to the Fedora compiler folks and Nick Clifton
> >> suggested this is a problem with the kernel:
> >>
> >>     This message comes from the recordmcount tool, which is part of the kernel
> >>     sources:
> >>
> >>     linux/scripts/recordmcount.[ch]
> >>
> >>     It appears to be triggered when a compiler update causes code to be
> >>     rearranged. The problem has been reported before in various forums,
> >>     but in particular I found this reference:
> >>
> >>     https://lore.kernel.org/lkml/20201204165742.3815221-2-arnd@kernel.org/
> >>
> >>     The point of which to me at least is that this is a kernel issue rather than
> >>     a compiler issue.  Ie there must be some weak symbols in kexec_file.o file
> >>     which need to be moved elsewhere.
> >
> >It could be arch_kexec_kernel_verify_sig() in kernel/kexec_file.c which
> >is __weak, but not implemented in any ARCH. If true, this has been
> >pointed out by Eric in one patch thread from Coiby.
> >
> >[PATCH v3 1/3] kexec: clean up arch_kexec_kernel_verify_sig
> >http://lkml.kernel.org/r/20211018083137.338757-2-coxu@redhat.com
> >
> >Maybe Coiby can fetch above config file and run the test to check.
>
> "[PATCH v3 1/3] kexec: clean up arch_kexec_kernel_verify_sig" alone
> would fix the error. If I turn arch_kexec_apply_relocations{_add,} into
> static function, the error would be gone. As attached is the patch would
> make this error disappear.
>

Thank you! I can confirm the attached patch fixes the problem.


Veronika

> However, s390 and x86 have its own implementation of
> arch_kexec_apply_relocations_add. This makes it looks like to be gcc's
> issue.
>
>
> >
> >Thanks
> >Baoquan
> >
>
> --
> Best regards,
> Coiby