1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * KUnits tests for CRC16.
4 *
5 * Copyright (C) 2024, LKCAMP
6 * Author: Vinicius Peixoto <vpeixoto@lkcamp.dev>
7 * Author: Fabricio Gasperin <fgasperin@lkcamp.dev>
8 * Author: Enzo Bertoloti <ebertoloti@lkcamp.dev>
9 */
10 #include <kunit/test.h>
11 #include <linux/crc16.h>
12 #include <linux/prandom.h>
13
14 #define CRC16_KUNIT_DATA_SIZE 4096
15 #define CRC16_KUNIT_TEST_SIZE 100
16 #define CRC16_KUNIT_SEED 0x12345678
17
18 /**
19 * struct crc16_test - CRC16 test data
20 * @crc: initial input value to CRC16
21 * @start: Start index within the data buffer
22 * @length: Length of the data
23 */
24 static struct crc16_test {
25 u16 crc;
26 u16 start;
27 u16 length;
28 } tests[CRC16_KUNIT_TEST_SIZE];
29
30 u8 data[CRC16_KUNIT_DATA_SIZE];
31
32
33 /* Naive implementation of CRC16 for validation purposes */
_crc16_naive_byte(u16 crc,u8 data)34 static inline u16 _crc16_naive_byte(u16 crc, u8 data)
35 {
36 u8 i = 0;
37
38 crc ^= (u16) data;
39 for (i = 0; i < 8; i++) {
40 if (crc & 0x01)
41 crc = (crc >> 1) ^ 0xa001;
42 else
43 crc = crc >> 1;
44 }
45
46 return crc;
47 }
48
49
_crc16_naive(u16 crc,u8 * buffer,size_t len)50 static inline u16 _crc16_naive(u16 crc, u8 *buffer, size_t len)
51 {
52 while (len--)
53 crc = _crc16_naive_byte(crc, *buffer++);
54 return crc;
55 }
56
57
58 /* Small helper for generating pseudorandom 16-bit data */
_rand16(void)59 static inline u16 _rand16(void)
60 {
61 static u32 rand = CRC16_KUNIT_SEED;
62
63 rand = next_pseudo_random32(rand);
64 return rand & 0xFFFF;
65 }
66
67
crc16_init_test_data(struct kunit_suite * suite)68 static int crc16_init_test_data(struct kunit_suite *suite)
69 {
70 size_t i;
71
72 /* Fill the data buffer with random bytes */
73 for (i = 0; i < CRC16_KUNIT_DATA_SIZE; i++)
74 data[i] = _rand16() & 0xFF;
75
76 /* Generate random test data while ensuring the random
77 * start + length values won't overflow the 4096-byte
78 * buffer (0x7FF * 2 = 0xFFE < 0x1000)
79 */
80 for (size_t i = 0; i < CRC16_KUNIT_TEST_SIZE; i++) {
81 tests[i].crc = _rand16();
82 tests[i].start = _rand16() & 0x7FF;
83 tests[i].length = _rand16() & 0x7FF;
84 }
85
86 return 0;
87 }
88
crc16_test_empty(struct kunit * test)89 static void crc16_test_empty(struct kunit *test)
90 {
91 u16 crc;
92
93 /* The result for empty data should be the same as the
94 * initial crc
95 */
96 crc = crc16(0x00, data, 0);
97 KUNIT_EXPECT_EQ(test, crc, 0);
98 crc = crc16(0xFF, data, 0);
99 KUNIT_EXPECT_EQ(test, crc, 0xFF);
100 }
101
crc16_test_correctness(struct kunit * test)102 static void crc16_test_correctness(struct kunit *test)
103 {
104 size_t i;
105 u16 crc, crc_naive;
106
107 for (i = 0; i < CRC16_KUNIT_TEST_SIZE; i++) {
108 /* Compare results with the naive crc16 implementation */
109 crc = crc16(tests[i].crc, data + tests[i].start,
110 tests[i].length);
111 crc_naive = _crc16_naive(tests[i].crc, data + tests[i].start,
112 tests[i].length);
113 KUNIT_EXPECT_EQ(test, crc, crc_naive);
114 }
115 }
116
117
crc16_test_combine(struct kunit * test)118 static void crc16_test_combine(struct kunit *test)
119 {
120 size_t i, j;
121 u16 crc, crc_naive;
122
123 /* Make sure that combining two consecutive crc16 calculations
124 * yields the same result as calculating the crc16 for the whole thing
125 */
126 for (i = 0; i < CRC16_KUNIT_TEST_SIZE; i++) {
127 crc_naive = crc16(tests[i].crc, data + tests[i].start, tests[i].length);
128 for (j = 0; j < tests[i].length; j++) {
129 crc = crc16(tests[i].crc, data + tests[i].start, j);
130 crc = crc16(crc, data + tests[i].start + j, tests[i].length - j);
131 KUNIT_EXPECT_EQ(test, crc, crc_naive);
132 }
133 }
134 }
135
136
137 static struct kunit_case crc16_test_cases[] = {
138 KUNIT_CASE(crc16_test_empty),
139 KUNIT_CASE(crc16_test_combine),
140 KUNIT_CASE(crc16_test_correctness),
141 {},
142 };
143
144 static struct kunit_suite crc16_test_suite = {
145 .name = "crc16",
146 .test_cases = crc16_test_cases,
147 .suite_init = crc16_init_test_data,
148 };
149 kunit_test_suite(crc16_test_suite);
150
151 MODULE_AUTHOR("Fabricio Gasperin <fgasperin@lkcamp.dev>");
152 MODULE_AUTHOR("Vinicius Peixoto <vpeixoto@lkcamp.dev>");
153 MODULE_AUTHOR("Enzo Bertoloti <ebertoloti@lkcamp.dev>");
154 MODULE_DESCRIPTION("Unit tests for crc16");
155 MODULE_LICENSE("GPL");
156