Fix compile failures due to arm64 includes in stable kernels

[Sebastian Kemper]

On Tue, Mar 27, 2018 at 05:23:47PM -0700, Stefano Stabellini wrote:
> On Sun, 25 Mar 2018, Sebastian Kemper wrote:
> > Hello all,
> > 
> > Some older stable kernels provide some arm64 headers like opcodes.h,
> > that include their non-64bit equivalents. For example:
> > 
> > arch/arm64/include/asm/opcodes.h
> > 
> > tries to include
> > 
> > <../../arm/include/asm/opcodes.h>
> > 
> > It's obvious that there is one hierarchy level missing. This causes
> > build failures:
> > 
> >     CC [M]  /build/lede-snapshots/aarch64_cortex-a53/build/sdk/build_dir/target-aarch64_cortex-a53_musl/linux-brcm2708_bcm2710/dahdi-linux-2.11.1-20180111/drivers/dahdi/dahdi-base.o
> >   In file included from ./arch/arm64/include/asm/sysreg.h:25:0,
> >                    from ./arch/arm64/include/asm/cputype.h:94,
> >                    from ./arch/arm64/include/asm/cachetype.h:19,
> >                    from ./arch/arm64/include/asm/cache.h:19,
> >                    from ./include/linux/cache.h:5,
> >                    from ./include/linux/printk.h:8,
> >                    from ./include/linux/kernel.h:13,
> >                    from /build/lede-snapshots/aarch64_cortex-a53/build/sdk/build_dir/target-aarch64_cortex-a53_musl/linux-brcm2708_bcm2710/dahdi-linux-2.11.1-20180111/drivers/dahdi/dahdi-base.c:38:
> >   ./arch/arm64/include/asm/opcodes.h:5:10: fatal error: ../../arm/include/asm/opcodes.h: No such file or directory
> >    #include <../../arm/include/asm/opcodes.h>
> >             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> >   compilation terminated.
> > 
> > Some example packages that fail to build are dahdi-linux and
> > cryptodev-linux.
> > 
> > linux-3.16.56:
> >   - does not have opcodes.h, but the xen headers
> > 
> >       hypercall.h
> >       interface.h
> >       hypervisor.h
> >       page.h
> >       
> >     have the wrong include lines.
> >     
> > linux-4.1.50:
> >   - affected (needs a small change in the patch for opcodes.h due to slightly different layout)
> >   
> > linux-4.4.123:
> >   - affected
> >   
> > linux-4.9.89:
> >   - affected
> > 
> > The attached patch fixes the includes.
> > 
> > I understand that to get a patch accepted into the stable series one
> > needs to provide a commit to master. But in this case that doesn't seem
> > possible as these headers do not exist anymore in newer kernels.
> > 
> > What do you think? Does the above make sense to you to backport to the
> > stable kernels?
> 
> It is not actually a bug: the path was correct given the way the
> Makefiles were written -- if you build a regular arm64 kernel with the
> default config and CONFIG_XEN enabled, it will work fine.
> 
> I am guessing you see these issues with out-of-tree modules, right?

Hi Stefano,

Correct. They're out-of-tree modules.

As this seems to imply that my suggested patch could result in in-tree
modules not compiling anymore, I'll just drop it.

Thanks for your feedback!

Kind regards,
Sebastian

> Fortunately, on newer kernels the whole thing has been reworked, and
> should solve the problem for you. The commit you are looking for is
> 2fbadc3002c5f172d20aa2e7e48920c5f14ed11f:
> 
> commit 7465c84a9380779235af42146dae6798b89b1d12
> Author: Marc Zyngier <marc.zyngier at arm.com>
> Date:   Fri Dec 2 14:19:35 2016 +0000
> 
>     arm/arm64: xen: Move shared architecture headers to include/xen/arm
>     
>     ARM and arm64 Xen ports share a number of headers, leading to
>     packaging issues when these headers needs to be exported, as it
>     breaks the reasonable requirement that an architecture port
>     has self-contained headers.
>     
>     Fix the issue by moving the 5 header files to include/xen/arm,
>     and keep local placeholders to include the relevant files.
>     
>     Signed-off-by: Marc Zyngier <marc.zyngier at arm.com>
>     Reviewed-by: Stefano Stabellini <sstabellini at kernel.org>
> 
> I am CC'ing the original author.