@@ -4,13 +4,27 @@
# Measure kernel stack entropy by sampling via LKDTM's REPORT_STACK test.
set -e
samples="${1:-1000}"
+TRIGGER=/sys/kernel/debug/provoke-crash/DIRECT
+KSELFTEST_SKIP_TEST=4
+
+# Verify we have LKDTM available in the kernel.
+if [ ! -r $TRIGGER ] ; then
+ /sbin/modprobe -q lkdtm || true
+ if [ ! -r $TRIGGER ] ; then
+ echo "Cannot find $TRIGGER (missing CONFIG_LKDTM?)"
+ else
+ echo "Cannot write $TRIGGER (need to run as root?)"
+ fi
+ # Skip this test
+ exit $KSELFTEST_SKIP_TEST
+fi
# Capture dmesg continuously since it may fill up depending on sample size.
log=$(mktemp -t stack-entropy-XXXXXX)
dmesg --follow >"$log" & pid=$!
report=-1
for i in $(seq 1 $samples); do
- echo "REPORT_STACK" >/sys/kernel/debug/provoke-crash/DIRECT
+ echo "REPORT_STACK" > $TRIGGER
if [ -t 1 ]; then
percent=$(( 100 * $i / $samples ))
if [ "$percent" -ne "$report" ]; then
Exit with return code 4 if lkdtm is not available like other tests in order to properly skip the test. Signed-off-by: Misono Tomohiro <misono.tomohiro@jp.fujitsu.com> --- I saw the same problem reported here (on 5.14-rc4): https://lore.kernel.org/lkml/2836f48a-d4e2-7f00-f06c-9f556fbd6332@linuxfoundation.org/ tools/testing/selftests/lkdtm/stack-entropy.sh | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-)