lib/crc16_kunit.c

   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 */
  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
  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 */
  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
  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
  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
 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
 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");