selftests/kselftest/runner.sh: Pass optional command parameters in environment

Some testcases allow for optional commandline parameters but as of now
there is now way to provide such arguments to the runner script.

Add support to retrieve such optional command parameters fron environment
variables named so as to include the all-uppercase test executable name,
sanitized substituting any non-acceptable varname characters with "_",
following the pattern:

KSELFTEST_<UPPERCASE_SANITIZED_TEST_NAME>_ARGS="options"

Optional command parameters support is not available if 'tr' is not
installed on the test system.

Cc: Kees Cook <[e-mail]>
Signed-off-by: Cristian Marussi <[e-mail]>
Signed-off-by: Shuah Khan <[e-mail]>

tools/testing/selftests/kselftest/runner.sh

···
 	exit 1
 fi
 
+TR_CMD=$(command -v tr)
+
 # If Perl is unavailable, we must fall back to line-at-a-time prefixing
 # with sed instead of unbuffered output.
 tap_prefix()
···
 
 	# Reset any "settings"-file variables.
 	export kselftest_timeout="$kselftest_default_timeout"
+
+	# Safe default if tr not available
+	kselftest_cmd_args_ref="KSELFTEST_ARGS"
+
+	# Optional arguments for this command, possibly defined as an
+	# environment variable built using the test executable in all
+	# uppercase and sanitized substituting non acceptable shell
+	# variable name characters with "_" as in:
+	#
+	# 	KSELFTEST_<UPPERCASE_SANITIZED_TESTNAME>_ARGS="<options>"
+	#
+	# e.g.
+	#
+	# 	rtctest --> KSELFTEST_RTCTEST_ARGS="/dev/rtc1"
+	#
+	# 	cpu-on-off-test.sh --> KSELFTEST_CPU_ON_OFF_TEST_SH_ARGS="-a -p 10"
+	#
+	if [ -n "$TR_CMD" ]; then
+		BASENAME_SANITIZED=$(echo "$BASENAME_TEST" | \
+					$TR_CMD -d "[:blank:][:cntrl:]" | \
+					$TR_CMD -c "[:alnum:]_" "_" | \
+					$TR_CMD [:lower:] [:upper:])
+		kselftest_cmd_args_ref="KSELFTEST_${BASENAME_SANITIZED}_ARGS"
+	fi
+
 	# Load per-test-directory kselftest "settings" file.
 	settings="$BASE_DIR/$DIR/settings"
 	if [ -r "$settings" ] ; then
···
 		echo "# Warning: file $TEST is missing!"
 		echo "not ok $test_num $TEST_HDR_MSG"
 	else
-		cmd="./$BASENAME_TEST"
+		eval kselftest_cmd_args="\$${kselftest_cmd_args_ref:-}"
+		cmd="./$BASENAME_TEST $kselftest_cmd_args"
 		if [ ! -x "$TEST" ]; then
 			echo "# Warning: file $TEST is not executable"