@@ -2850,6 +2850,15 @@ config USERCOPY_KUNIT_TEST
on the copy_to/from_user infrastructure, making sure basic
user/kernel boundary testing is working.
+config CRC16_KUNIT_TEST
+ tristate "KUnit tests for CRC16"
+ depends on KUNIT
+ default KUNIT_ALL_TESTS
+ select CRC16
+ help
+ Enable this option to run unit tests for the kernel's CRC16
+ implementation (<linux/crc16.h>).
+
config TEST_UDELAY
tristate "udelay test driver"
help
@@ -389,6 +389,7 @@ CFLAGS_fortify_kunit.o += $(DISABLE_STRUCTLEAK_PLUGIN)
obj-$(CONFIG_FORTIFY_KUNIT_TEST) += fortify_kunit.o
obj-$(CONFIG_SIPHASH_KUNIT_TEST) += siphash_kunit.o
obj-$(CONFIG_USERCOPY_KUNIT_TEST) += usercopy_kunit.o
+obj-$(CONFIG_CRC16_KUNIT_TEST) += crc16_kunit.o
obj-$(CONFIG_GENERIC_LIB_DEVMEM_IS_ALLOWED) += devmem_is_allowed.o
new file mode 100644
@@ -0,0 +1,165 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * KUnits tests for CRC16.
+ *
+ * Copyright (C) 2024, LKCAMP
+ * Author: Vinicius Peixoto <vpeixoto@lkcamp.dev>
+ * Author: Fabricio Gasperin <fgasperin@lkcamp.dev>
+ * Author: Enzo Bertoloti <ebertoloti@lkcamp.dev>
+ */
+#include <kunit/test.h>
+#include <linux/crc16.h>
+#include <linux/prandom.h>
+
+#define CRC16_KUNIT_DATA_SIZE 4096
+#define CRC16_KUNIT_TEST_SIZE 100
+#define CRC16_KUNIT_SEED 0x12345678
+
+/**
+ * struct crc16_test - CRC16 test data
+ * @crc: initial input value to CRC16
+ * @start: Start index within the data buffer
+ * @length: Length of the data
+ * @crc16: Expected CRC16 value for the test
+ */
+static struct crc16_test {
+ u16 crc;
+ u16 start;
+ u16 length;
+} tests[CRC16_KUNIT_TEST_SIZE];
+
+u8 data[CRC16_KUNIT_DATA_SIZE];
+
+
+/* Naive implementation of CRC16 for validation purposes */
+static inline u16 _crc16_naive_byte(u16 crc, u8 data)
+{
+ u8 i = 0;
+
+ crc ^= (u16) data;
+ for (i = 0; i < 8; i++) {
+ if (crc & 0x01)
+ crc = (crc >> 1) ^ 0xa001;
+ else
+ crc = crc >> 1;
+ }
+
+ return crc;
+}
+
+
+static inline u16 _crc16_naive(u16 crc, u8 *buffer, size_t len)
+{
+ while (len--)
+ crc = _crc16_naive_byte(crc, *buffer++);
+ return crc;
+}
+
+
+/* Small helper for generating pseudorandom 16-bit data */
+static inline u16 _rand16(void)
+{
+ static u32 rand = CRC16_KUNIT_SEED;
+
+ rand = next_pseudo_random32(rand);
+ return rand & 0xFFFF;
+}
+
+
+static int crc16_init_test_data(struct kunit_suite *suite)
+{
+ size_t i;
+
+ /* Fill the data buffer with random bytes */
+ for (i = 0; i < CRC16_KUNIT_DATA_SIZE; i++)
+ data[i] = _rand16() & 0xFF;
+
+ /* Generate random test data while ensuring the random
+ * start + length values won't overflow the 4096-byte
+ * buffer (0x7FF * 2 = 0xFFE < 0x1000)
+ */
+ for (size_t i = 0; i < CRC16_KUNIT_TEST_SIZE; i++) {
+ tests[i].crc = _rand16();
+ tests[i].start = _rand16() & 0x7FF;
+ tests[i].length = _rand16() & 0x7FF;
+ }
+
+ return 0;
+}
+
+/**
+ * crc16_test_empty - Test crc16 with empty data
+ *
+ * Test crc16 with empty data, the result should be the same as the initial crc
+ */
+static void crc16_test_empty(struct kunit *test)
+{
+ u16 crc;
+
+ crc = crc16(0x00, data, 0);
+ KUNIT_EXPECT_EQ(test, crc, 0);
+ crc = crc16(0xFF, data, 0);
+ KUNIT_EXPECT_EQ(test, crc, 0xFF);
+}
+
+/**
+ * crc16_test_correctness - Test crc16
+ *
+ * Test crc16 against a naive implementation
+ */
+static void crc16_test_correctness(struct kunit *test)
+{
+ size_t i;
+ u16 crc, crc_naive;
+
+ for (i = 0; i < CRC16_KUNIT_TEST_SIZE; i++) {
+ crc = crc16(tests[i].crc, data + tests[i].start,
+ tests[i].length);
+ crc_naive = _crc16_naive(tests[i].crc, data + tests[i].start,
+ tests[i].length);
+ KUNIT_EXPECT_EQ(test, crc, crc_naive);
+ }
+}
+
+
+/**
+ * crc16_test_combine - Test split crc16 calculations
+ *
+ * Test crc16 with data split in two parts, the result should be the same as
+ * crc16 with the data combined
+ */
+static void crc16_test_combine(struct kunit *test)
+{
+ size_t i, j;
+ u16 crc, crc_naive;
+
+ for (i = 0; i < CRC16_KUNIT_TEST_SIZE; i++) {
+ crc_naive = crc16(tests[i].crc, data + tests[i].start, tests[i].length);
+ for (j = 0; j < tests[i].length; j++) {
+ crc = crc16(tests[i].crc, data + tests[i].start, j);
+ crc = crc16(crc, data + tests[i].start + j, tests[i].length - j);
+ KUNIT_EXPECT_EQ(test, crc, crc_naive);
+ }
+ }
+}
+
+
+static struct kunit_case crc16_test_cases[] = {
+ KUNIT_CASE(crc16_test_empty),
+ KUNIT_CASE(crc16_test_combine),
+ KUNIT_CASE(crc16_test_correctness),
+ {},
+};
+
+static struct kunit_suite crc16_test_suite = {
+ .name = "crc16",
+ .test_cases = crc16_test_cases,
+ .suite_init = crc16_init_test_data,
+};
+kunit_test_suite(crc16_test_suite);
+
+MODULE_AUTHOR("Fabricio Gasperin <fgasperin@lkcamp.dev>");
+MODULE_AUTHOR("Vinicius Peixoto <vpeixoto@lkcamp.dev>");
+MODULE_AUTHOR("Enzo Bertoloti <ebertoloti@lkcamp.dev>");
+MODULE_DESCRIPTION("Unit tests for crc16");
+MODULE_LICENSE("GPL");