string: Convert selftest to KUnit

Convert test_string.c to KUnit so it can be easily run with everything
else.

Additional text context is retained for failure reporting. For example,
when forcing a bad match, we can see the loop counters reported for the
memset() tests:

[09:21:52]     # test_memset64: ASSERTION FAILED at lib/string_kunit.c:93
[09:21:52]     Expected v == 0xa2a1a1a1a1a1a1a1ULL, but
[09:21:52]         v == -6799976246779207263 (0xa1a1a1a1a1a1a1a1)
[09:21:52]         0xa2a1a1a1a1a1a1a1ULL == -6727918652741279327 (0xa2a1a1a1a1a1a1a1)
[09:21:52] i:0 j:0 k:0
[09:21:52] [FAILED] test_memset64

Currently passes without problems:

$ ./tools/testing/kunit/kunit.py run string
...
[09:37:40] Starting KUnit Kernel (1/1)...
[09:37:40] ============================================================
[09:37:40] =================== string (6 subtests) ====================
[09:37:40] [PASSED] test_memset16
[09:37:40] [PASSED] test_memset32
[09:37:40] [PASSED] test_memset64
[09:37:40] [PASSED] test_strchr
[09:37:40] [PASSED] test_strnchr
[09:37:40] [PASSED] test_strspn
[09:37:40] ===================== [PASSED] string ======================
[09:37:40] ============================================================
[09:37:40] Testing complete. Ran 6 tests: passed: 6
[09:37:40] Elapsed time: 6.730s total, 0.001s configuring, 6.562s building, 0.131s running

Link: https://lore.kernel.org/r/20240301202732.2688342-1-keescook@chromium.org
Signed-off-by: Kees Cook <keescook@chromium.org>

5 files changed, 205 insertions, 261 deletions

diff --git a/MAINTAINERS b/MAINTAINERS
index cd651c4df019..9f1f68cccd6a 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -8976,9 +8976,9 @@ F:	include/linux/string.h
 F:	include/linux/string_choices.h
 F:	include/linux/string_helpers.h
 F:	lib/string.c
+F:	lib/string_kunit.c
 F:	lib/string_helpers.c
 F:	lib/test-string_helpers.c
-F:	lib/test_string.c
 F:	scripts/coccinelle/api/string_choices.cocci
 
 GENERIC UIO DRIVER FOR PCI DEVICES
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 4e2febe3b568..406cdf353488 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -2352,8 +2352,10 @@ config ASYNC_RAID6_TEST
 config TEST_HEXDUMP
 	tristate "Test functions located in the hexdump module at runtime"
 
-config STRING_SELFTEST
-	tristate "Test string functions at runtime"
+config STRING_KUNIT_TEST
+	tristate "KUnit test string functions at runtime" if !KUNIT_ALL_TESTS
+	depends on KUNIT
+	default KUNIT_ALL_TESTS
 
 config TEST_STRING_HELPERS
 	tristate "Test functions located in the string_helpers module at runtime"
diff --git a/lib/Makefile b/lib/Makefile
index eae87c41b22b..946277c37831 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -49,7 +49,7 @@ obj-y += bcd.o sort.o parser.o debug_locks.o random32.o \
 	 percpu-refcount.o rhashtable.o base64.o \
 	 once.o refcount.o rcuref.o usercopy.o errseq.o bucket_locks.o \
 	 generic-radix-tree.o bitmap-str.o
-obj-$(CONFIG_STRING_SELFTEST) += test_string.o
+obj-$(CONFIG_STRING_KUNIT_TEST) += string_kunit.o
 obj-y += string_helpers.o
 obj-$(CONFIG_TEST_STRING_HELPERS) += test-string_helpers.o
 obj-y += hexdump.o
diff --git a/lib/string_kunit.c b/lib/string_kunit.c
new file mode 100644
index 000000000000..eabf025cf77c
--- /dev/null
+++ b/lib/string_kunit.c
@@ -0,0 +1,199 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Test cases for string functions.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <kunit/test.h>
+#include <linux/module.h>
+#include <linux/printk.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+
+static void test_memset16(struct kunit *test)
+{
+	unsigned i, j, k;
+	u16 v, *p;
+
+	p = kunit_kzalloc(test, 256 * 2 * 2, GFP_KERNEL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, p);
+
+	for (i = 0; i < 256; i++) {
+		for (j = 0; j < 256; j++) {
+			memset(p, 0xa1, 256 * 2 * sizeof(v));
+			memset16(p + i, 0xb1b2, j);
+			for (k = 0; k < 512; k++) {
+				v = p[k];
+				if (k < i) {
+					KUNIT_ASSERT_EQ_MSG(test, v, 0xa1a1,
+						"i:%d j:%d k:%d", i, j, k);
+				} else if (k < i + j) {
+					KUNIT_ASSERT_EQ_MSG(test, v, 0xb1b2,
+						"i:%d j:%d k:%d", i, j, k);
+				} else {
+					KUNIT_ASSERT_EQ_MSG(test, v, 0xa1a1,
+						"i:%d j:%d k:%d", i, j, k);
+				}
+			}
+		}
+	}
+}
+
+static void test_memset32(struct kunit *test)
+{
+	unsigned i, j, k;
+	u32 v, *p;
+
+	p = kunit_kzalloc(test, 256 * 2 * 4, GFP_KERNEL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, p);
+
+	for (i = 0; i < 256; i++) {
+		for (j = 0; j < 256; j++) {
+			memset(p, 0xa1, 256 * 2 * sizeof(v));
+			memset32(p + i, 0xb1b2b3b4, j);
+			for (k = 0; k < 512; k++) {
+				v = p[k];
+				if (k < i) {
+					KUNIT_ASSERT_EQ_MSG(test, v, 0xa1a1a1a1,
+						"i:%d j:%d k:%d", i, j, k);
+				} else if (k < i + j) {
+					KUNIT_ASSERT_EQ_MSG(test, v, 0xb1b2b3b4,
+						"i:%d j:%d k:%d", i, j, k);
+				} else {
+					KUNIT_ASSERT_EQ_MSG(test, v, 0xa1a1a1a1,
+						"i:%d j:%d k:%d", i, j, k);
+				}
+			}
+		}
+	}
+}
+
+static void test_memset64(struct kunit *test)
+{
+	unsigned i, j, k;
+	u64 v, *p;
+
+	p = kunit_kzalloc(test, 256 * 2 * 8, GFP_KERNEL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, p);
+
+	for (i = 0; i < 256; i++) {
+		for (j = 0; j < 256; j++) {
+			memset(p, 0xa1, 256 * 2 * sizeof(v));
+			memset64(p + i, 0xb1b2b3b4b5b6b7b8ULL, j);
+			for (k = 0; k < 512; k++) {
+				v = p[k];
+				if (k < i) {
+					KUNIT_ASSERT_EQ_MSG(test, v, 0xa1a1a1a1a1a1a1a1ULL,
+						"i:%d j:%d k:%d", i, j, k);
+				} else if (k < i + j) {
+					KUNIT_ASSERT_EQ_MSG(test, v, 0xb1b2b3b4b5b6b7b8ULL,
+						"i:%d j:%d k:%d", i, j, k);
+				} else {
+					KUNIT_ASSERT_EQ_MSG(test, v, 0xa1a1a1a1a1a1a1a1ULL,
+						"i:%d j:%d k:%d", i, j, k);
+				}
+			}
+		}
+	}
+}
+
+static void test_strchr(struct kunit *test)
+{
+	const char *test_string = "abcdefghijkl";
+	const char *empty_string = "";
+	char *result;
+	int i;
+
+	for (i = 0; i < strlen(test_string) + 1; i++) {
+		result = strchr(test_string, test_string[i]);
+		KUNIT_ASSERT_EQ_MSG(test, result - test_string, i,
+				    "char:%c", 'a' + i);
+	}
+
+	result = strchr(empty_string, '\0');
+	KUNIT_ASSERT_PTR_EQ(test, result, empty_string);
+
+	result = strchr(empty_string, 'a');
+	KUNIT_ASSERT_NULL(test, result);
+
+	result = strchr(test_string, 'z');
+	KUNIT_ASSERT_NULL(test, result);
+}
+
+static void test_strnchr(struct kunit *test)
+{
+	const char *test_string = "abcdefghijkl";
+	const char *empty_string = "";
+	char *result;
+	int i, j;
+
+	for (i = 0; i < strlen(test_string) + 1; i++) {
+		for (j = 0; j < strlen(test_string) + 2; j++) {
+			result = strnchr(test_string, j, test_string[i]);
+			if (j <= i) {
+				KUNIT_ASSERT_NULL_MSG(test, result,
+					"char:%c i:%d j:%d", 'a' + i, i, j);
+			} else {
+				KUNIT_ASSERT_EQ_MSG(test, result - test_string, i,
+					"char:%c i:%d j:%d", 'a' + i, i, j);
+			}
+		}
+	}
+
+	result = strnchr(empty_string, 0, '\0');
+	KUNIT_ASSERT_NULL(test, result);
+
+	result = strnchr(empty_string, 1, '\0');
+	KUNIT_ASSERT_PTR_EQ(test, result, empty_string);
+
+	result = strnchr(empty_string, 1, 'a');
+	KUNIT_ASSERT_NULL(test, result);
+
+	result = strnchr(NULL, 0, '\0');
+	KUNIT_ASSERT_NULL(test, result);
+}
+
+static void test_strspn(struct kunit *test)
+{
+	static const struct strspn_test {
+		const char str[16];
+		const char accept[16];
+		const char reject[16];
+		unsigned a;
+		unsigned r;
+	} tests[] = {
+		{ "foobar", "", "", 0, 6 },
+		{ "abba", "abc", "ABBA", 4, 4 },
+		{ "abba", "a", "b", 1, 1 },
+		{ "", "abc", "abc", 0, 0},
+	};
+	const struct strspn_test *s = tests;
+	size_t i;
+
+	for (i = 0; i < ARRAY_SIZE(tests); ++i, ++s) {
+		KUNIT_ASSERT_EQ_MSG(test, s->a, strspn(s->str, s->accept),
+			"i:%zu", i);
+		KUNIT_ASSERT_EQ_MSG(test, s->r, strcspn(s->str, s->reject),
+			"i:%zu", i);
+	}
+}
+
+static struct kunit_case string_test_cases[] = {
+	KUNIT_CASE(test_memset16),
+	KUNIT_CASE(test_memset32),
+	KUNIT_CASE(test_memset64),
+	KUNIT_CASE(test_strchr),
+	KUNIT_CASE(test_strnchr),
+	KUNIT_CASE(test_strspn),
+	{}
+};
+
+static struct kunit_suite string_test_suite = {
+	.name = "string",
+	.test_cases = string_test_cases,
+};
+
+kunit_test_suites(&string_test_suite);
+
+MODULE_LICENSE("GPL v2");
diff --git a/lib/test_string.c b/lib/test_string.c
deleted file mode 100644
index c5cb92fb710e..000000000000
--- a/lib/test_string.c
+++ /dev/null
@@ -1,257 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0-only
-#include <linux/module.h>
-#include <linux/printk.h>
-#include <linux/slab.h>
-#include <linux/string.h>
-
-static __init int memset16_selftest(void)
-{
-	unsigned i, j, k;
-	u16 v, *p;
-
-	p = kmalloc(256 * 2 * 2, GFP_KERNEL);
-	if (!p)
-		return -1;
-
-	for (i = 0; i < 256; i++) {
-		for (j = 0; j < 256; j++) {
-			memset(p, 0xa1, 256 * 2 * sizeof(v));
-			memset16(p + i, 0xb1b2, j);
-			for (k = 0; k < 512; k++) {
-				v = p[k];
-				if (k < i) {
-					if (v != 0xa1a1)
-						goto fail;
-				} else if (k < i + j) {
-					if (v != 0xb1b2)
-						goto fail;
-				} else {
-					if (v != 0xa1a1)
-						goto fail;
-				}
-			}
-		}
-	}
-
-fail:
-	kfree(p);
-	if (i < 256)
-		return (i << 24) | (j << 16) | k | 0x8000;
-	return 0;
-}
-
-static __init int memset32_selftest(void)
-{
-	unsigned i, j, k;
-	u32 v, *p;
-
-	p = kmalloc(256 * 2 * 4, GFP_KERNEL);
-	if (!p)
-		return -1;
-
-	for (i = 0; i < 256; i++) {
-		for (j = 0; j < 256; j++) {
-			memset(p, 0xa1, 256 * 2 * sizeof(v));
-			memset32(p + i, 0xb1b2b3b4, j);
-			for (k = 0; k < 512; k++) {
-				v = p[k];
-				if (k < i) {
-					if (v != 0xa1a1a1a1)
-						goto fail;
-				} else if (k < i + j) {
-					if (v != 0xb1b2b3b4)
-						goto fail;
-				} else {
-					if (v != 0xa1a1a1a1)
-						goto fail;
-				}
-			}
-		}
-	}
-
-fail:
-	kfree(p);
-	if (i < 256)
-		return (i << 24) | (j << 16) | k | 0x8000;
-	return 0;
-}
-
-static __init int memset64_selftest(void)
-{
-	unsigned i, j, k;
-	u64 v, *p;
-
-	p = kmalloc(256 * 2 * 8, GFP_KERNEL);
-	if (!p)
-		return -1;
-
-	for (i = 0; i < 256; i++) {
-		for (j = 0; j < 256; j++) {
-			memset(p, 0xa1, 256 * 2 * sizeof(v));
-			memset64(p + i, 0xb1b2b3b4b5b6b7b8ULL, j);
-			for (k = 0; k < 512; k++) {
-				v = p[k];
-				if (k < i) {
-					if (v != 0xa1a1a1a1a1a1a1a1ULL)
-						goto fail;
-				} else if (k < i + j) {
-					if (v != 0xb1b2b3b4b5b6b7b8ULL)
-						goto fail;
-				} else {
-					if (v != 0xa1a1a1a1a1a1a1a1ULL)
-						goto fail;
-				}
-			}
-		}
-	}
-
-fail:
-	kfree(p);
-	if (i < 256)
-		return (i << 24) | (j << 16) | k | 0x8000;
-	return 0;
-}
-
-static __init int strchr_selftest(void)
-{
-	const char *test_string = "abcdefghijkl";
-	const char *empty_string = "";
-	char *result;
-	int i;
-
-	for (i = 0; i < strlen(test_string) + 1; i++) {
-		result = strchr(test_string, test_string[i]);
-		if (result - test_string != i)
-			return i + 'a';
-	}
-
-	result = strchr(empty_string, '\0');
-	if (result != empty_string)
-		return 0x101;
-
-	result = strchr(empty_string, 'a');
-	if (result)
-		return 0x102;
-
-	result = strchr(test_string, 'z');
-	if (result)
-		return 0x103;
-
-	return 0;
-}
-
-static __init int strnchr_selftest(void)
-{
-	const char *test_string = "abcdefghijkl";
-	const char *empty_string = "";
-	char *result;
-	int i, j;
-
-	for (i = 0; i < strlen(test_string) + 1; i++) {
-		for (j = 0; j < strlen(test_string) + 2; j++) {
-			result = strnchr(test_string, j, test_string[i]);
-			if (j <= i) {
-				if (!result)
-					continue;
-				return ((i + 'a') << 8) | j;
-			}
-			if (result - test_string != i)
-				return ((i + 'a') << 8) | j;
-		}
-	}
-
-	result = strnchr(empty_string, 0, '\0');
-	if (result)
-		return 0x10001;
-
-	result = strnchr(empty_string, 1, '\0');
-	if (result != empty_string)
-		return 0x10002;
-
-	result = strnchr(empty_string, 1, 'a');
-	if (result)
-		return 0x10003;
-
-	result = strnchr(NULL, 0, '\0');
-	if (result)
-		return 0x10004;
-
-	return 0;
-}
-
-static __init int strspn_selftest(void)
-{
-	static const struct strspn_test {
-		const char str[16];
-		const char accept[16];
-		const char reject[16];
-		unsigned a;
-		unsigned r;
-	} tests[] __initconst = {
-		{ "foobar", "", "", 0, 6 },
-		{ "abba", "abc", "ABBA", 4, 4 },
-		{ "abba", "a", "b", 1, 1 },
-		{ "", "abc", "abc", 0, 0},
-	};
-	const struct strspn_test *s = tests;
-	size_t i, res;
-
-	for (i = 0; i < ARRAY_SIZE(tests); ++i, ++s) {
-		res = strspn(s->str, s->accept);
-		if (res != s->a)
-			return 0x100 + 2*i;
-		res = strcspn(s->str, s->reject);
-		if (res != s->r)
-			return 0x100 + 2*i + 1;
-	}
-	return 0;
-}
-
-static __exit void string_selftest_remove(void)
-{
-}
-
-static __init int string_selftest_init(void)
-{
-	int test, subtest;
-
-	test = 1;
-	subtest = memset16_selftest();
-	if (subtest)
-		goto fail;
-
-	test = 2;
-	subtest = memset32_selftest();
-	if (subtest)
-		goto fail;
-
-	test = 3;
-	subtest = memset64_selftest();
-	if (subtest)
-		goto fail;
-
-	test = 4;
-	subtest = strchr_selftest();
-	if (subtest)
-		goto fail;
-
-	test = 5;
-	subtest = strnchr_selftest();
-	if (subtest)
-		goto fail;
-
-	test = 6;
-	subtest = strspn_selftest();
-	if (subtest)
-		goto fail;
-
-	pr_info("String selftests succeeded\n");
-	return 0;
-fail:
-	pr_crit("String selftest failure %d.%08x\n", test, subtest);
-	return 0;
-}
-
-module_init(string_selftest_init);
-module_exit(string_selftest_remove);
-MODULE_LICENSE("GPL v2");