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From:   Ard Biesheuvel <ard.biesheuvel@linaro.org>
Date:   Wed, 21 Nov 2018 22:44:16 +0100
Message-ID: <CAKv+Gu-jnppk-zJnqij-J6CwW0Vf4xZw+uESGWBCHoyk3ZEgDA@mail.gmail.com>
Subject: Re: Out of tree module build errors since v4.20-rc1
To:     namit@vmware.com, Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        "H. Peter Anvin" <hpa@zytor.com>,
        "the arch/x86 maintainers" <x86@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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On Wed, 21 Nov 2018 at 22:15, Liam R. Howlett <Liam.Howlett@oracle.com> wro=
te:
>
> * Nadav Amit <namit@vmware.com> [181121 16:12]:
> > > On Nov 21, 2018, at 12:56 PM, Liam R. Howlett <Liam.Howlett@Oracle.co=
m> wrote:
> > >
> > >
> > > My out of tree driver build is now reporting issues with the jump tab=
le:
> > >
> > > ./include/linux/jump_label.h: In function =E2=80=98jump_entry_code=E2=
=80=99:
> > > ./include/linux/jump_label.h:153:14: error: dereferencing pointer to =
incomplete type =E2=80=98const struct jump_entry=E2=80=99
> > >  return entry->code;
> > >              ^~
> > > ./include/linux/jump_label.h: In function =E2=80=98jump_entry_set_ini=
t=E2=80=99:
> > > ./include/linux/jump_label.h:180:7: error: dereferencing pointer to i=
ncomplete type =E2=80=98struct jump_entry=E2=80=99
> > >  entry->key |=3D 2;
> > >       ^~
> > > ./include/linux/jump_label.h: At top level:
> > > ./include/linux/jump_label.h:212:26: error: array type has incomplete=
 element type =E2=80=98struct jump_entry=E2=80=99
> > > extern struct jump_entry __start___jump_table[];
> > >                          ^~~~~~~~~~~~~~~~~~~~
> > > ./include/linux/jump_label.h:213:26: error: array type has incomplete=
 element type =E2=80=98struct jump_entry=E2=80=99
> > > extern struct jump_entry __stop___jump_table[];
> > >                          ^~~~~~~~~~~~~~~~~~~
> > >
> > >
> > > This happens in v4.20-rc3 as well, so I bisected between v4.19 to
> > > v4.20-rc1 which resulted in the following commit:
> > >
> > > b34006c4258c9c86597b6b7123d6a9a3513d6cd7 is the first bad commit
> > > commit b34006c4258c9c86597b6b7123d6a9a3513d6cd7
> > > Author: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> > > Date:   Tue Sep 18 23:51:41 2018 -0700
> > >
> > >    x86/jump_table: Use relative references
> > >
> > >
> > >
> > >
> > > Initially I assumed this was my own fault, but my module does not hav=
e
> > > these issues when using v4.19.  Is there anything I should try/change=
 in
> > > my module makefile, includes, etc to support this relative reference
> > > code?
> >
> > Do you see HAVE_ARCH_JUMP_LABEL_RELATIVE set in your kernel config?
> >
>
> Yes:
>  $ grep HAVE_ARCH_JUMP_LABEL_RELATIVE .config
>  CONFIG_HAVE_ARCH_JUMP_LABEL_RELATIVE=3Dy
>
>
> I should have mentioned I ran 'make defoldconfig' between each bisect.

That is puzzling. linux/jump_label.h defines a type struct
jump_label_entry if CONFIG_HAVE_ARCH_JUMP_LABEL_RELATIVE is #define'd,
and so the error suggests that it is not.

Can you share the command line (with V=3D1) and the preprocessed result?
(Re-execute the failing GCC command but replace -c with -E)