lib/math/test_div64.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2021  Maciej W. Rozycki
   4  */
   5
   6 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
   7
   8 #include <linux/init.h>
   9 #include <linux/ktime.h>
  10 #include <linux/module.h>
  11 #include <linux/printk.h>
  12 #include <linux/time64.h>
  13 #include <linux/types.h>
  14
  15 #include <asm/div64.h>
  16
  17 #define TEST_DIV64_N_ITER 1024
  18
  19 static const u64 test_div64_dividends[] = {
  20         0x00000000ab275080,
  21         0x0000000fe73c1959,
  22         0x000000e54c0a74b1,
  23         0x00000d4398ff1ef9,
  24         0x0000a18c2ee1c097,
  25         0x00079fb80b072e4a,
  26         0x0072db27380dd689,
  27         0x0842f488162e2284,
  28         0xf66745411d8ab063,
  29 };
  30 #define SIZE_DIV64_DIVIDENDS ARRAY_SIZE(test_div64_dividends)
  31
  32 #define TEST_DIV64_DIVISOR_0 0x00000009
  33 #define TEST_DIV64_DIVISOR_1 0x0000007c
  34 #define TEST_DIV64_DIVISOR_2 0x00000204
  35 #define TEST_DIV64_DIVISOR_3 0x0000cb5b
  36 #define TEST_DIV64_DIVISOR_4 0x00010000
  37 #define TEST_DIV64_DIVISOR_5 0x0008a880
  38 #define TEST_DIV64_DIVISOR_6 0x003fd3ae
  39 #define TEST_DIV64_DIVISOR_7 0x0b658fac
  40 #define TEST_DIV64_DIVISOR_8 0xdc08b349
  41
  42 static const u32 test_div64_divisors[] = {
  43         TEST_DIV64_DIVISOR_0,
  44         TEST_DIV64_DIVISOR_1,
  45         TEST_DIV64_DIVISOR_2,
  46         TEST_DIV64_DIVISOR_3,
  47         TEST_DIV64_DIVISOR_4,
  48         TEST_DIV64_DIVISOR_5,
  49         TEST_DIV64_DIVISOR_6,
  50         TEST_DIV64_DIVISOR_7,
  51         TEST_DIV64_DIVISOR_8,
  52 };
  53 #define SIZE_DIV64_DIVISORS ARRAY_SIZE(test_div64_divisors)
  54
  55 static const struct {
  56         u64 quotient;
  57         u32 remainder;
  58 } test_div64_results[SIZE_DIV64_DIVISORS][SIZE_DIV64_DIVIDENDS] = {
  59         {
  60                 { 0x0000000013045e47, 0x00000001 },
  61                 { 0x000000000161596c, 0x00000030 },
  62                 { 0x000000000054e9d4, 0x00000130 },
  63                 { 0x000000000000d776, 0x0000278e },
  64                 { 0x000000000000ab27, 0x00005080 },
  65                 { 0x00000000000013c4, 0x0004ce80 },
  66                 { 0x00000000000002ae, 0x001e143c },
  67                 { 0x000000000000000f, 0x0033e56c },
  68                 { 0x0000000000000000, 0xab275080 },
  69         }, {
  70                 { 0x00000001c45c02d1, 0x00000000 },
  71                 { 0x0000000020d5213c, 0x00000049 },
  72                 { 0x0000000007e3d65f, 0x000001dd },
  73                 { 0x0000000000140531, 0x000065ee },
  74                 { 0x00000000000fe73c, 0x00001959 },
  75                 { 0x000000000001d637, 0x0004e5d9 },
  76                 { 0x0000000000003fc9, 0x000713bb },
  77                 { 0x0000000000000165, 0x029abe7d },
  78                 { 0x0000000000000012, 0x6e9f7e37 },
  79         }, {
  80                 { 0x000000197a3a0cf7, 0x00000002 },
  81                 { 0x00000001d9632e5c, 0x00000021 },
  82                 { 0x0000000071c28039, 0x000001cd },
  83                 { 0x000000000120a844, 0x0000b885 },
  84                 { 0x0000000000e54c0a, 0x000074b1 },
  85                 { 0x00000000001a7bb3, 0x00072331 },
  86                 { 0x00000000000397ad, 0x0002c61b },
  87                 { 0x000000000000141e, 0x06ea2e89 },
  88                 { 0x000000000000010a, 0xab002ad7 },
  89         }, {
  90                 { 0x0000017949e37538, 0x00000001 },
  91                 { 0x0000001b62441f37, 0x00000055 },
  92                 { 0x0000000694a3391d, 0x00000085 },
  93                 { 0x0000000010b2a5d2, 0x0000a753 },
  94                 { 0x000000000d4398ff, 0x00001ef9 },
  95                 { 0x0000000001882ec6, 0x0005cbf9 },
  96                 { 0x000000000035333b, 0x0017abdf },
  97                 { 0x00000000000129f1, 0x0ab4520d },
  98                 { 0x0000000000000f6e, 0x8ac0ce9b },
  99         }, {
 100                 { 0x000011f321a74e49, 0x00000006 },
 101                 { 0x0000014d8481d211, 0x0000005b },
 102                 { 0x0000005025cbd92d, 0x000001e3 },
 103                 { 0x00000000cb5e71e3, 0x000043e6 },
 104                 { 0x00000000a18c2ee1, 0x0000c097 },
 105                 { 0x0000000012a88828, 0x00036c97 },
 106                 { 0x000000000287f16f, 0x002c2a25 },
 107                 { 0x00000000000e2cc7, 0x02d581e3 },
 108                 { 0x000000000000bbf4, 0x1ba08c03 },
 109         }, {
 110                 { 0x0000d8db8f72935d, 0x00000005 },
 111                 { 0x00000fbd5aed7a2e, 0x00000002 },
 112                 { 0x000003c84b6ea64a, 0x00000122 },
 113                 { 0x0000000998fa8829, 0x000044b7 },
 114                 { 0x000000079fb80b07, 0x00002e4a },
 115                 { 0x00000000e16b20fa, 0x0002a14a },
 116                 { 0x000000001e940d22, 0x00353b2e },
 117                 { 0x0000000000ab40ac, 0x06fba6ba },
 118                 { 0x000000000008debd, 0x72d98365 },
 119         }, {
 120                 { 0x000cc3045b8fc281, 0x00000000 },
 121                 { 0x0000ed1f48b5c9fc, 0x00000079 },
 122                 { 0x000038fb9c63406a, 0x000000e1 },
 123                 { 0x000000909705b825, 0x00000a62 },
 124                 { 0x00000072db27380d, 0x0000d689 },
 125                 { 0x0000000d43fce827, 0x00082b09 },
 126                 { 0x00000001ccaba11a, 0x0037e8dd },
 127                 { 0x000000000a13f729, 0x0566dffd },
 128                 { 0x000000000085a14b, 0x23d36726 },
 129         }, {
 130                 { 0x00eafeb9c993592b, 0x00000001 },
 131                 { 0x00110e5befa9a991, 0x00000048 },
 132                 { 0x00041947b4a1d36a, 0x000000dc },
 133                 { 0x00000a6679327311, 0x0000c079 },
 134                 { 0x00000842f488162e, 0x00002284 },
 135                 { 0x000000f4459740fc, 0x00084484 },
 136                 { 0x0000002122c47bf9, 0x002ca446 },
 137                 { 0x00000000b9936290, 0x004979c4 },
 138                 { 0x00000000099ca89d, 0x9db446bf },
 139         }, {
 140                 { 0x1b60cece589da1d2, 0x00000001 },
 141                 { 0x01fcb42be1453f5b, 0x0000004f },
 142                 { 0x007a3f2457df0749, 0x0000013f },
 143                 { 0x0001363130e3ec7b, 0x000017aa },
 144                 { 0x0000f66745411d8a, 0x0000b063 },
 145                 { 0x00001c757dfab350, 0x00048863 },
 146                 { 0x000003dc4979c652, 0x00224ea7 },
 147                 { 0x000000159edc3144, 0x06409ab3 },
 148                 { 0x000000011eadfee3, 0xa99c48a8 },
 149         },
 150 };
 151
 152 static inline bool test_div64_verify(u64 quotient, u32 remainder, int i, int j)
 153 {
 154         return (quotient == test_div64_results[i][j].quotient &&
 155                 remainder == test_div64_results[i][j].remainder);
 156 }
 157
 158 /*
 159  * This needs to be a macro, because we don't want to rely on the compiler
 160  * to do constant propagation, and `do_div' may take a different path for
 161  * constants, so we do want to verify that as well.
 162  */
 163 #define test_div64_one(dividend, divisor, i, j) ({                      \
 164         bool result = true;                                             \
 165         u64 quotient;                                                   \
 166         u32 remainder;                                                  \
 167                                                                         \
 168         quotient = dividend;                                            \
 169         remainder = do_div(quotient, divisor);                          \
 170         if (!test_div64_verify(quotient, remainder, i, j)) {            \
 171                 pr_err("ERROR: %016llx / %08x => %016llx,%08x\n",       \
 172                        dividend, divisor, quotient, remainder);         \
 173                 pr_err("ERROR: expected value              => %016llx,%08x\n",\
 174                        test_div64_results[i][j].quotient,               \
 175                        test_div64_results[i][j].remainder);             \
 176                 result = false;                                         \
 177         }                                                               \
 178         result;                                                         \
 179 })
 180
 181 /*
 182  * Run calculation for the same divisor value expressed as a constant
 183  * and as a variable, so as to verify the implementation for both cases
 184  * should they be handled by different code execution paths.
 185  */
 186 static bool __init test_div64(void)
 187 {
 188         u64 dividend;
 189         int i, j;
 190
 191         for (i = 0; i < SIZE_DIV64_DIVIDENDS; i++) {
 192                 dividend = test_div64_dividends[i];
 193                 if (!test_div64_one(dividend, TEST_DIV64_DIVISOR_0, i, 0))
 194                         return false;
 195                 if (!test_div64_one(dividend, TEST_DIV64_DIVISOR_1, i, 1))
 196                         return false;
 197                 if (!test_div64_one(dividend, TEST_DIV64_DIVISOR_2, i, 2))
 198                         return false;
 199                 if (!test_div64_one(dividend, TEST_DIV64_DIVISOR_3, i, 3))
 200                         return false;
 201                 if (!test_div64_one(dividend, TEST_DIV64_DIVISOR_4, i, 4))
 202                         return false;
 203                 if (!test_div64_one(dividend, TEST_DIV64_DIVISOR_5, i, 5))
 204                         return false;
 205                 if (!test_div64_one(dividend, TEST_DIV64_DIVISOR_6, i, 6))
 206                         return false;
 207                 if (!test_div64_one(dividend, TEST_DIV64_DIVISOR_7, i, 7))
 208                         return false;
 209                 if (!test_div64_one(dividend, TEST_DIV64_DIVISOR_8, i, 8))
 210                         return false;
 211                 for (j = 0; j < SIZE_DIV64_DIVISORS; j++) {
 212                         if (!test_div64_one(dividend, test_div64_divisors[j],
 213                                             i, j))
 214                                 return false;
 215                 }
 216         }
 217         return true;
 218 }
 219
 220 static int __init test_div64_init(void)
 221 {
 222         struct timespec64 ts, ts0, ts1;
 223         int i;
 224
 225         pr_info("Starting 64bit/32bit division and modulo test\n");
 226         ktime_get_ts64(&ts0);
 227
 228         for (i = 0; i < TEST_DIV64_N_ITER; i++)
 229                 if (!test_div64())
 230                         break;
 231
 232         ktime_get_ts64(&ts1);
 233         ts = timespec64_sub(ts1, ts0);
 234         pr_info("Completed 64bit/32bit division and modulo test, "
 235                 "%llu.%09lus elapsed\n", ts.tv_sec, ts.tv_nsec);
 236
 237         return 0;
 238 }
 239
 240 static void __exit test_div64_exit(void)
 241 {
 242 }
 243
 244 module_init(test_div64_init);
 245 module_exit(test_div64_exit);
 246
 247 MODULE_AUTHOR("Maciej W. Rozycki <macro@orcam.me.uk>");
 248 MODULE_LICENSE("GPL");
 249 MODULE_DESCRIPTION("64bit/32bit division and modulo test module");