1 files changed, 81 insertions, 0 deletions
diff --git a/tools/testing/selftests/rcutorture/bin/mkinitrd.sh b/tools/testing/selftests/rcutorture/bin/mkinitrd.sh
new file mode 100755
index 000000000..38e424d23
--- /dev/null
+++ b/tools/testing/selftests/rcutorture/bin/mkinitrd.sh
@@ -0,0 +1,81 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0+
+#
+# Create an initrd directory if one does not already exist.
+#
+# Copyright (C) IBM Corporation, 2013
+#
+# Author: Connor Shu <Connor.Shu@ibm.com>
+
+D=tools/testing/selftests/rcutorture
+
+# Prerequisite checks
+[ -z "$D" ] && echo >&2 "No argument supplied" && exit 1
+if [ ! -d "$D" ]; then
+    echo >&2 "$D does not exist: Malformed kernel source tree?"
+    exit 1
+fi
+if [ -s "$D/initrd/init" ]; then
+    echo "$D/initrd/init already exists, no need to create it"
+    exit 0
+fi
+
+# Create a C-language initrd/init infinite-loop program and statically
+# link it.  This results in a very small initrd.
+echo "Creating a statically linked C-language initrd"
+cd $D
+mkdir -p initrd
+cd initrd
+cat > init.c << '___EOF___'
+#ifndef NOLIBC
+#include <unistd.h>
+#include <sys/time.h>
+#endif
+
+volatile unsigned long delaycount;
+
+int main(int argc, int argv[])
+{
+	int i;
+	struct timeval tv;
+	struct timeval tvb;
+
+	for (;;) {
+		sleep(1);
+		/* Need some userspace time. */
+		if (gettimeofday(&tvb, NULL))
+			continue;
+		do {
+			for (i = 0; i < 1000 * 100; i++)
+				delaycount = i * i;
+			if (gettimeofday(&tv, NULL))
+				break;
+			tv.tv_sec -= tvb.tv_sec;
+			if (tv.tv_sec > 1)
+				break;
+			tv.tv_usec += tv.tv_sec * 1000 * 1000;
+			tv.tv_usec -= tvb.tv_usec;
+		} while (tv.tv_usec < 1000);
+	}
+	return 0;
+}
+___EOF___
+
+# build using nolibc on supported archs (smaller executable) and fall
+# back to regular glibc on other ones.
+if echo -e "#if __x86_64__||__i386__||__i486__||__i586__||__i686__" \
+           "||__ARM_EABI__||__aarch64__\nyes\n#endif" \
+   | ${CROSS_COMPILE}gcc -E -nostdlib -xc - \
+   | grep -q '^yes'; then
+	# architecture supported by nolibc
+        ${CROSS_COMPILE}gcc -fno-asynchronous-unwind-tables -fno-ident \
+		-nostdlib -include ../../../../include/nolibc/nolibc.h \
+		-lgcc -s -static -Os -o init init.c
+else
+	${CROSS_COMPILE}gcc -s -static -Os -o init init.c
+fi
+
+rm init.c
+echo "Done creating a statically linked C-language initrd"
+
+exit 0