From 578fc08b825515eab0991445076dfb92743864f2 Mon Sep 17 00:00:00 2001
From: Mathias Krause <minipli@grsecurity.net>
Date: Thu, 28 Sep 2023 11:19:08 +0200
Subject: [PATCH] memory_driver: Support overriding kernel directory

Support compiling the module against a different kernel version than the
currently running one by allowing to set either KVER or KDIR variables
on the make commandline.

Also modernize the makefile slightly and make use of the kernel's
'clean' target to ensure to remove all generated files.

Signed-off-by: Mathias Krause <minipli@grsecurity.net>
---
 memory_driver/Makefile | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/memory_driver/Makefile b/memory_driver/Makefile
index d0f3ccc..61ee7c0 100644
--- a/memory_driver/Makefile
+++ b/memory_driver/Makefile
@@ -8,9 +8,14 @@
 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 # GNU General Public License for more details.
 #
+ifneq ($(KERNELRELEASE),)
 obj-m := crash.o
+else
 PWD := $(shell pwd)
+KVER ?= $(shell uname -r)
+KDIR ?= /lib/modules/${KVER}/build
 all:
-	make -C /lib/modules/`uname -r`/build M=${PWD} SUBDIRS=${PWD} modules
+	${MAKE} -C ${KDIR} M=${PWD} SUBDIRS=${PWD} modules
 clean:
-	rm -f *.mod.c *.ko *.o Module.*
+	test -e ${KDIR}/Makefile && ${MAKE} -C ${KDIR} M=${PWD} SUBDIRS=${PWD} clean || ${RM} *.mod.c *.ko *.o Module.*
+endif