From fb321206590906d04a4158edeb96d9896fd0621a Mon Sep 17 00:00:00 2001
From: Balazs Gerofi <bgerofi@riken.jp>
Date: Sat, 2 Apr 2016 15:43:35 -0400
Subject: [PATCH] make mcoverlayfs optional (default: enabled)

---
 arch/x86/tools/mcreboot-smp-x86.sh.in   |  3 ++-
 configure                               | 23 +++++++++++++++++++++++
 configure.ac                            | 14 ++++++++++++++
 executer/config.h.in                    |  3 +++
 executer/kernel/mcoverlayfs/Makefile.in |  9 +++++++--
 executer/user/mcexec.c                  |  6 +++++-
 6 files changed, 54 insertions(+), 4 deletions(-)

diff --git a/arch/x86/tools/mcreboot-smp-x86.sh.in b/arch/x86/tools/mcreboot-smp-x86.sh.in
index 74ce951d..27abe1a8 100644
--- a/arch/x86/tools/mcreboot-smp-x86.sh.in
+++ b/arch/x86/tools/mcreboot-smp-x86.sh.in
@@ -17,6 +17,7 @@ BINDIR="@BINDIR@"
 SBINDIR="@SBINDIR@"
 KMODDIR="@KMODDIR@"
 KERNDIR="@KERNDIR@"
+ENABLE_MCOVERLAYFS="@ENABLE_MCOVERLAYFS@"
 
 INTERVAL=1
 LOGMODE=0
@@ -59,7 +60,7 @@ cpus=""
 ihk_ikc_irq_core=0
 
 kernel_release=`uname -r`
-enable_mcoverlay=`if [[ ${kernel_release} =~ ^4.* ]]; then echo "yes"; fi`
+enable_mcoverlay=`if [[ ${kernel_release} =~ ^4.* && "${ENABLE_MCOVERLAYFS}" == "yes" ]]; then echo "yes"; fi`
 
 
 if [ "$cpus" == "" ]; then
diff --git a/configure b/configure
index 13ebef98..7aa92998 100755
--- a/configure
+++ b/configure
@@ -628,6 +628,7 @@ IHK_RELEASE_DATE
 DCFA_VERSION
 MCKERNEL_VERSION
 IHK_VERSION
+ENABLE_MCOVERLAYFS
 MANDIR
 KERNDIR
 KMODDIR
@@ -693,6 +694,7 @@ with_target
 with_system_map
 enable_dcfa
 enable_memdump
+enable_mcoverlayfs
 '
       ac_precious_vars='build_alias
 host_alias
@@ -1314,6 +1316,7 @@ Optional Features:
   --enable-FEATURE[=ARG]  include FEATURE [ARG=yes]
   --enable-dcfa           Enable DCFA modules
   --enable-memdump        enable dumping memory and analyzing a dump
+  --enable-mcoverlayfs    enable mcoverlayfs implementation
 
 Optional Packages:
   --with-PACKAGE[=ARG]    use PACKAGE [ARG=yes]
@@ -2100,6 +2103,14 @@ else
 fi
 
 
+# Check whether --enable-mcoverlayfs was given.
+if test "${enable_mcoverlayfs+set}" = set; then :
+  enableval=$enable_mcoverlayfs; ENABLE_MCOVERLAYFS=$enableval
+else
+  ENABLE_MCOVERLAYFS=yes
+fi
+
+
 case "X$WITH_KERNELSRC" in
     Xyes | Xno | X)
 	WITH_KERNELSRC='/lib/modules/`uname -r`/build'
@@ -3817,6 +3828,18 @@ $as_echo "$as_me: memdump feature is disabled" >&6;}
 	uncomment_if_ENABLE_MEMDUMP='#'
 fi
 
+if test "x$ENABLE_MCOVERLAYFS" = "xyes" ; then
+
+$as_echo "#define ENABLE_MCOVERLAYFS 1" >>confdefs.h
+
+	{ $as_echo "$as_me:${as_lineno-$LINENO}: mcoverlayfs is enabled" >&5
+$as_echo "$as_me: mcoverlayfs is enabled" >&6;}
+else
+	{ $as_echo "$as_me:${as_lineno-$LINENO}: mcoverlayfs is disabled" >&5
+$as_echo "$as_me: mcoverlayfs is disabled" >&6;}
+fi
+
+
 
 
 
diff --git a/configure.ac b/configure.ac
index 78b011c6..d6c773d6 100644
--- a/configure.ac
+++ b/configure.ac
@@ -42,6 +42,12 @@ AC_ARG_ENABLE([memdump],
 	      [ENABLE_MEMDUMP=$enableval],
 	      [ENABLE_MEMDUMP=default])
 
+AC_ARG_ENABLE([mcoverlayfs],
+	      AC_HELP_STRING([--enable-mcoverlayfs],
+			     [enable mcoverlayfs implementation]),
+	      [ENABLE_MCOVERLAYFS=$enableval],
+	      [ENABLE_MCOVERLAYFS=yes])
+
 case "X$WITH_KERNELSRC" in
     Xyes | Xno | X)
 	WITH_KERNELSRC='/lib/modules/`uname -r`/build'
@@ -257,6 +263,13 @@ else
 	uncomment_if_ENABLE_MEMDUMP='#'
 fi
 
+if test "x$ENABLE_MCOVERLAYFS" = "xyes" ; then
+	AC_DEFINE([ENABLE_MCOVERLAYFS],[1],[whether mcoverlayfs is enabled])
+	AC_MSG_NOTICE([mcoverlayfs is enabled])
+else
+	AC_MSG_NOTICE([mcoverlayfs is disabled])
+fi
+
 AC_SUBST(CC)
 AC_SUBST(XCC)
 AC_SUBST(ARCH)
@@ -267,6 +280,7 @@ AC_SUBST(SBINDIR)
 AC_SUBST(KMODDIR)
 AC_SUBST(KERNDIR)
 AC_SUBST(MANDIR)
+AC_SUBST(ENABLE_MCOVERLAYFS)
 
 AC_SUBST(IHK_VERSION)
 AC_SUBST(MCKERNEL_VERSION)
diff --git a/executer/config.h.in b/executer/config.h.in
index f0154b3f..03471096 100644
--- a/executer/config.h.in
+++ b/executer/config.h.in
@@ -1,5 +1,8 @@
 /* executer/config.h.in.  Generated from configure.ac by autoheader.  */
 
+/* whether mcoverlayfs is enabled */
+#undef ENABLE_MCOVERLAYFS
+
 /* whether memdump feature is enabled */
 #undef ENABLE_MEMDUMP
 
diff --git a/executer/kernel/mcoverlayfs/Makefile.in b/executer/kernel/mcoverlayfs/Makefile.in
index ce711014..13c9236b 100644
--- a/executer/kernel/mcoverlayfs/Makefile.in
+++ b/executer/kernel/mcoverlayfs/Makefile.in
@@ -2,9 +2,14 @@ KDIR ?= @KDIR@
 ARCH ?= @ARCH@
 KMODDIR=@KMODDIR@
 src = @abs_srcdir@
+ENABLE_MCOVERLAYFS=@ENABLE_MCOVERLAYFS@
 
-RELEASE=$(shell uname -r)
-ENABLE_BUILD=$(shell if [[ ${RELEASE} =~ ^4.* ]]; then echo "yes"; fi)
+RELEASE=$(shell uname -r | cut -d"." -f1)
+ifeq ($(ENABLE_MCOVERLAYFS),yes)
+ENABLE_BUILD=$(shell if [ "${RELEASE}" == "4" ]; then echo "yes"; fi)
+else
+ENABLE_BUILD=no
+endif
 
 obj-m += mcoverlay.o
 
diff --git a/executer/user/mcexec.c b/executer/user/mcexec.c
index a49ccf54..fd40612b 100644
--- a/executer/user/mcexec.c
+++ b/executer/user/mcexec.c
@@ -1089,6 +1089,7 @@ void init_worker_threads(int fd)
 	pthread_barrier_wait(&init_ready);
 }
 
+#ifdef ENABLE_MCOVERLAYFS
 #if LINUX_VERSION_CODE >= KERNEL_VERSION(4,0,0)
 #define READ_BUFSIZE 1024
 static int isunshare(void)
@@ -1162,6 +1163,7 @@ static int isunshare(void)
 	return err;
 }
 #endif
+#endif // ENABLE_MCOVERLAYFS
 
 #define MCK_RLIMIT_AS	0
 #define MCK_RLIMIT_CORE	1
@@ -1349,6 +1351,7 @@ int main(int argc, char **argv)
 		return 1;
 	}
 
+#ifdef ENABLE_MCOVERLAYFS
 #if LINUX_VERSION_CODE >= KERNEL_VERSION(4,0,0)
 	__dprintf("mcoverlay enable\n");
 	char mcos_procdir[PATH_MAX];
@@ -1397,9 +1400,10 @@ int main(int argc, char **argv)
 	} else if (error == -1) {
 		return 1;
 	}
+#endif // LINUX_VERSION_CODE >= KERNEL_VERSION(4,0,0)
 #else
 	__dprintf("mcoverlay disable\n");
-#endif
+#endif // ENABLE_MCOVERLAYFS
 
 	if (lookup_exec_path(argv[optind], path, sizeof(path)) != 0) {
 		fprintf(stderr, "error: finding file: %s\n", argv[optind]);