[3.16.y-ckt stable] Patch "arm64: vdso: fix build error when switching from LE to BE" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    arm64: vdso: fix build error when switching from LE to BE

to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.16.y-queue

This patch is scheduled to be released in version 3.16.7-ckt11.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.16.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 8b0caebcc05caf02d88ea24b72d87cb46d6d705e Mon Sep 17 00:00:00 2001
From: Arun Chandran <achandran at mvista.com>
Date: Thu, 26 Jun 2014 15:16:03 +0530
Subject: arm64: vdso: fix build error when switching from LE to BE

commit 1915e2ad1cf548217c963121e4076b3d44dd0169 upstream.

Building a kernel with CPU_BIG_ENDIAN fails if there are stale objects
from a !CPU_BIG_ENDIAN build. Due to a missing FORCE prerequisite on an
if_changed rule in the VDSO Makefile, we attempt to link a stale LE
object into the new BE kernel.

According to Documentation/kbuild/makefiles.txt, FORCE is required for
if_changed rules and forgetting it is a common mistake, so fix it by
'Forcing' the build of vdso. This patch fixes build errors like these:

arch/arm64/kernel/vdso/note.o: compiled for a little endian system and target is big endian
failed to merge target specific data of file arch/arm64/kernel/vdso/note.o

arch/arm64/kernel/vdso/sigreturn.o: compiled for a little endian system and target is big endian
failed to merge target specific data of file arch/arm64/kernel/vdso/sigreturn.o

Tested-by: Mark Rutland <mark.rutland at arm.com>
Signed-off-by: Arun Chandran <achandran at mvista.com>
Signed-off-by: Will Deacon <will.deacon at arm.com>
Cc: Guenter Roeck <linux at roeck-us.net>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 arch/arm64/kernel/vdso/Makefile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/kernel/vdso/Makefile b/arch/arm64/kernel/vdso/Makefile
index 6d20b7d162d8..a268a9af0c2d 100644
--- a/arch/arm64/kernel/vdso/Makefile
+++ b/arch/arm64/kernel/vdso/Makefile
@@ -43,7 +43,7 @@ $(obj)/vdso-offsets.h: $(obj)/vdso.so.dbg FORCE
 	$(call if_changed,vdsosym)

 # Assembly rules for the .S files
-$(obj-vdso): %.o: %.S
+$(obj-vdso): %.o: %.S FORCE
 	$(call if_changed_dep,vdsoas)

 # Actual build commands