arm, kbuild: make "make install" not depend on vmlinux

Install targets (install, zinstall, uinstall) on arm have a dependency
to vmlinux. This may cause parts of the kernel to be rebuilt during
installation. We must avoid this since this may run as root. Install
targets "ABSOLUTELY MUST NOT MODIFY THE SOURCE TREE." as Linus
emphasized this in:

 http://lkml.org/lkml/2013/7/10/600

So on arm and maybe other archs we need the same as for x86:

 1648e4f8 x86, kbuild: make "make install" not depend on vmlinux

This patch fixes this for arm. Dependencies are removed and instead a
check to install.sh is added for the files that are needed.

This issue was uncovered by this build error where the -j option is
used in conjunction with install targets:

 $ make <makeflags>
 $ make <makeflags> zinstall
 ...
   DEPMOD
 Usage: .../scripts/depmod.sh /sbin/depmod <kernelrelease>

(INSTALL_MOD_PATH and INSTALL_PATH variables set, so no root perms
required in this case.)

The problem is that zinstall on arm due to its dependency to vmlinux
does a prepare/prepare3 and finally does a forced rewrite of
kernel.release even if it exists already.

Rebuilding kernel.release removes it first and then recreates it. This
might race with another parallel make job running depmod.

So this patch should fix this one too.

Also quoting $(KERNELRELEASE) arg for install.sh as this messes
argument order in case it is empty (which is the case if the kernel
was not built yet).

Signed-off-by: Robert Richter <robert.richter@linaro.org>
Signed-off-by: Robert Richter <rric@kernel.org>
Acked-by: Michal Marek <mmarek@suse.cz>.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Michal Marek <mmarek@suse.cz>

1 files changed, 14 insertions, 0 deletions

diff --git a/arch/arm/boot/install.sh b/arch/arm/boot/install.sh
index 06ea7d42ce8e..2a45092a40e3 100644
--- a/arch/arm/boot/install.sh
+++ b/arch/arm/boot/install.sh
@@ -20,6 +20,20 @@
 #   $4 - default install path (blank if root directory)
 #
 
+verify () {
+	if [ ! -f "$1" ]; then
+		echo ""                                                   1>&2
+		echo " *** Missing file: $1"                              1>&2
+		echo ' *** You need to run "make" before "make install".' 1>&2
+		echo ""                                                   1>&2
+		exit 1
+	fi
+}
+
+# Make sure the files actually exist
+verify "$2"
+verify "$3"
+
 # User may have a custom install script
 if [ -x ~/bin/${INSTALLKERNEL} ]; then exec ~/bin/${INSTALLKERNEL} "$@"; fi
 if [ -x /sbin/${INSTALLKERNEL} ]; then exec /sbin/${INSTALLKERNEL} "$@"; fi