tests: add test for kernel segmentation fault

As asked by Daniel Vetter, this is a tech which checks if we can cause
division by zero in kernel by reading the i915_emon_status debugfs
entry repeatably.

Signed-off-by: Eugeni Dodonov <eugeni.dodonov@intel.com>

tests/Makefile.am

@@ -56,6 +56,7 @@ TESTS_progs = \
 
 TESTS_scripts = \
 	debugfs_reader \
+	debugfs_emon_crash \
 	$(NULL)
 
 kernel_tests = \

tests/debugfs_emon_crash

@@ -0,0 +1,34 @@
+#!/bin/sh
+#
+# This check if we can crash the kernel with segmentation-fault
+# by reading /sys/kernel/debug/dri/0/i915_emon_status too quickly
+#
+
+if [ -d /debug/dri ] ; then
+	debugfs_path=/debug_dri
+fi
+
+if [ -d /sys/kernel/debug/dri ] ; then
+	debugfs_path=/sys/kernel/debug/dri
+fi
+
+i915_path=x
+for dir in `ls $debugfs_path` ; do
+	if [ -f $debugfs_path/$dir/i915_error_state ] ; then
+		i915_path=$debugfs_path/$dir
+		break
+	fi
+done
+
+if [ $i915_path = "x" ] ; then
+	echo i915 debugfs path not found.
+	exit 1
+fi
+
+for z in $(seq 1 1000); do
+	cat $i915_path/i915_emon_status > /dev/null
+done
+
+# If we got here, we haven't crashed
+
+exit 0