mm/damon: add user space selftests

This commit adds a simple user space tests for DAMON. The tests are using
kselftest framework.

Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: SeongJae Park <[e-mail]>
Reviewed-by: Markus Boehme <[e-mail]>
Cc: Alexander Shishkin <[e-mail]>
Cc: Amit Shah <[e-mail]>
Cc: Benjamin Herrenschmidt <[e-mail]>
Cc: Brendan Higgins <[e-mail]>
Cc: David Hildenbrand <[e-mail]>
Cc: David Rientjes <[e-mail]>
Cc: David Woodhouse <[e-mail]>
Cc: Fan Du <[e-mail]>
Cc: Fernand Sieber <[e-mail]>
Cc: Greg Kroah-Hartman <[e-mail]>
Cc: Greg Thelen <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: Joe Perches <[e-mail]>
Cc: Jonathan Cameron <[e-mail]>
Cc: Jonathan Corbet <[e-mail]>
Cc: Leonard Foerster <[e-mail]>
Cc: Marco Elver <[e-mail]>
Cc: Maximilian Heyne <[e-mail]>
Cc: Mel Gorman <[e-mail]>
Cc: Minchan Kim <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: Rik van Riel <[e-mail]>
Cc: Shakeel Butt <[e-mail]>
Cc: Shuah Khan <[e-mail]>
Cc: Steven Rostedt (VMware) <[e-mail]>
Cc: Vladimir Davydov <[e-mail]>
Cc: Vlastimil Babka <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

tools/testing/selftests/damon/Makefile

···
+# SPDX-License-Identifier: GPL-2.0
+# Makefile for damon selftests
+
+TEST_FILES = _chk_dependency.sh
+TEST_PROGS = debugfs_attrs.sh
+
+include ../lib.mk

tools/testing/selftests/damon/_chk_dependency.sh

···
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+
+# Kselftest framework requirement - SKIP code is 4.
+ksft_skip=4
+
+DBGFS=/sys/kernel/debug/damon
+
+if [ $EUID -ne 0 ];
+then
+	echo "Run as root"
+	exit $ksft_skip
+fi
+
+if [ ! -d "$DBGFS" ]
+then
+	echo "$DBGFS not found"
+	exit $ksft_skip
+fi
+
+for f in attrs target_ids monitor_on
+do
+	if [ ! -f "$DBGFS/$f" ]
+	then
+		echo "$f not found"
+		exit 1
+	fi
+done

tools/testing/selftests/damon/debugfs_attrs.sh

···
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+
+test_write_result() {
+	file=$1
+	content=$2
+	orig_content=$3
+	expect_reason=$4
+	expected=$5
+
+	echo "$content" > "$file"
+	if [ $? -ne "$expected" ]
+	then
+		echo "writing $content to $file doesn't return $expected"
+		echo "expected because: $expect_reason"
+		echo "$orig_content" > "$file"
+		exit 1
+	fi
+}
+
+test_write_succ() {
+	test_write_result "$1" "$2" "$3" "$4" 0
+}
+
+test_write_fail() {
+	test_write_result "$1" "$2" "$3" "$4" 1
+}
+
+test_content() {
+	file=$1
+	orig_content=$2
+	expected=$3
+	expect_reason=$4
+
+	content=$(cat "$file")
+	if [ "$content" != "$expected" ]
+	then
+		echo "reading $file expected $expected but $content"
+		echo "expected because: $expect_reason"
+		echo "$orig_content" > "$file"
+		exit 1
+	fi
+}
+
+source ./_chk_dependency.sh
+
+# Test attrs file
+# ===============
+
+file="$DBGFS/attrs"
+orig_content=$(cat "$file")
+
+test_write_succ "$file" "1 2 3 4 5" "$orig_content" "valid input"
+test_write_fail "$file" "1 2 3 4" "$orig_content" "no enough fields"
+test_write_fail "$file" "1 2 3 5 4" "$orig_content" \
+	"min_nr_regions > max_nr_regions"
+test_content "$file" "$orig_content" "1 2 3 4 5" "successfully written"
+echo "$orig_content" > "$file"
+
+# Test target_ids file
+# ====================
+
+file="$DBGFS/target_ids"
+orig_content=$(cat "$file")
+
+test_write_succ "$file" "1 2 3 4" "$orig_content" "valid input"
+test_write_succ "$file" "1 2 abc 4" "$orig_content" "still valid input"
+test_content "$file" "$orig_content" "1 2" "non-integer was there"
+test_write_succ "$file" "abc 2 3" "$orig_content" "the file allows wrong input"
+test_content "$file" "$orig_content" "" "wrong input written"
+test_write_succ "$file" "" "$orig_content" "empty input"
+test_content "$file" "$orig_content" "" "empty input written"
+echo "$orig_content" > "$file"
+
+echo "PASS"