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
test_div64_verify(u64 quotient,u32 remainder,int i,int j)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 */
test_div64(void)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
test_div64_init(void)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
test_div64_exit(void)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");
250