selftests/livepatch: refine dmesg 'taints' in dmesg comparison

The livepatch selftests currently grep on "taints" to filter out
"tainting kernel with TAINT_LIVEPATCH" messages which may be logged when
loading livepatch modules.

Further filter the log to drop "loading out-of-tree module taints
kernel" in the rare case the klp_test modules have been built
out-of-tree.

Look for the longer "taints kernel" or "tainting kernel" strings to
avoid inadvertent partial matching.

Signed-off-by: Joe Lawrence <[email protected]>
Reviewed-by: Kamalesh Babulal <[email protected]>
Reviewed-by: Yannick Cote <[email protected]>
Reviewed-by: Petr Mladek <[email protected]>
Acked-by: Miroslav Benes <[email protected]>
Signed-off-by: Petr Mladek <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

Author: joe-lawrence

tools/testing/selftests/livepatch/functions.sh

@@ -277,7 +277,8 @@ function check_result {
 	# post-comparison sed filter.
 
 	result=$(dmesg | diff --changed-group-format='%>' --unchanged-group-format='' "$SAVED_DMESG" - | \
-		 grep -v 'tainting' | grep -e 'livepatch:' -e 'test_klp' | \
+		 grep -e 'livepatch:' -e 'test_klp' | \
+		 grep -v '\(tainting\|taints\) kernel' | \
 		 sed 's/^\[[ 0-9.]*\] //')
 
 	if [[ "$expect" == "$result" ]] ; then