x86/kbuild: enable modversions for symbols exported from asm

x86/kbuild: enable modversions for symbols exported from asm

commit 334bb773876403eae3457d81be0b8ea70f8e4ccc upstream.

Commit 4efca4ed ("kbuild: modversions for EXPORT_SYMBOL() for asm") adds
modversion support for symbols exported from asm files. Architectures
must include C-style declarations for those symbols in asm/asm-prototypes.h
in order for them to be versioned.

Add these declarations for x86, and an architecture-independent file that
can be used for common symbols.

With f27c2f6 reverting 8ab2ae6 ("default exported asm symbols to zero") we
produce a scary warning on x86, this commit fixes that.

Signed-off-by: Adam Borowski <kilobyte@angband.pl>
Tested-by: Kalle Valo <kvalo@codeaurora.org>
Acked-by: Nicholas Piggin <npiggin@gmail.com>
Tested-by: Peter Wu <peter@lekensteyn.nl>
Tested-by: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: Michal Marek <mmarek@suse.com>
Signed-off-by: Razvan Ghitulete <rga@amazon.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Orabug: 27477743
CVE: CVE-2017-5715
(cherry picked from commit b76ac90af34dc08f057da15aa34584a0a3d381b5)
Signed-off-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Pavel Tatashin <pasha.tatashin@oracle.com>