aboutsummaryrefslogtreecommitdiff
path: root/lib/math/test_div64.c
blob: eca8e8c6afe0b5a3d479e00017497de6940ded8d (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2021  Maciej W. Rozycki
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/init.h>
#include <linux/ktime.h>
#include <linux/module.h>
#include <linux/printk.h>
#include <linux/time64.h>
#include <linux/types.h>

#include <asm/div64.h>

#define TEST_DIV64_N_ITER 1024

static const u64 test_div64_dividents[] = {
	0x00000000ab275080,
	0x0000000fe73c1959,
	0x000000e54c0a74b1,
	0x00000d4398ff1ef9,
	0x0000a18c2ee1c097,
	0x00079fb80b072e4a,
	0x0072db27380dd689,
	0x0842f488162e2284,
	0xf66745411d8ab063,
};
#define SIZE_DIV64_DIVIDENTS ARRAY_SIZE(test_div64_dividents)

#define TEST_DIV64_DIVISOR_0 0x00000009
#define TEST_DIV64_DIVISOR_1 0x0000007c
#define TEST_DIV64_DIVISOR_2 0x00000204
#define TEST_DIV64_DIVISOR_3 0x0000cb5b
#define TEST_DIV64_DIVISOR_4 0x00010000
#define TEST_DIV64_DIVISOR_5 0x0008a880
#define TEST_DIV64_DIVISOR_6 0x003fd3ae
#define TEST_DIV64_DIVISOR_7 0x0b658fac
#define TEST_DIV64_DIVISOR_8 0xdc08b349

static const u32 test_div64_divisors[] = {
	TEST_DIV64_DIVISOR_0,
	TEST_DIV64_DIVISOR_1,
	TEST_DIV64_DIVISOR_2,
	TEST_DIV64_DIVISOR_3,
	TEST_DIV64_DIVISOR_4,
	TEST_DIV64_DIVISOR_5,
	TEST_DIV64_DIVISOR_6,
	TEST_DIV64_DIVISOR_7,
	TEST_DIV64_DIVISOR_8,
};
#define SIZE_DIV64_DIVISORS ARRAY_SIZE(test_div64_divisors)

static const struct {
	u64 quotient;
	u32 remainder;
} test_div64_results[SIZE_DIV64_DIVISORS][SIZE_DIV64_DIVIDENTS] = {
	{
		{ 0x0000000013045e47, 0x00000001 },
		{ 0x000000000161596c, 0x00000030 },
		{ 0x000000000054e9d4, 0x00000130 },
		{ 0x000000000000d776, 0x0000278e },
		{ 0x000000000000ab27, 0x00005080 },
		{ 0x00000000000013c4, 0x0004ce80 },
		{ 0x00000000000002ae, 0x001e143c },
		{ 0x000000000000000f, 0x0033e56c },
		{ 0x0000000000000000, 0xab275080 },
	}, {
		{ 0x00000001c45c02d1, 0x00000000 },
		{ 0x0000000020d5213c, 0x00000049 },
		{ 0x0000000007e3d65f, 0x000001dd },
		{ 0x0000000000140531, 0x000065ee },
		{ 0x00000000000fe73c, 0x00001959 },
		{ 0x000000000001d637, 0x0004e5d9 },
		{ 0x0000000000003fc9, 0x000713bb },
		{ 0x0000000000000165, 0x029abe7d },
		{ 0x0000000000000012, 0x6e9f7e37 },
	}, {
		{ 0x000000197a3a0cf7, 0x00000002 },
		{ 0x00000001d9632e5c, 0x00000021 },
		{ 0x0000000071c28039, 0x000001cd },
		{ 0x000000000120a844, 0x0000b885 },
		{ 0x0000000000e54c0a, 0x000074b1 },
		{ 0x00000000001a7bb3, 0x00072331 },
		{ 0x00000000000397ad, 0x0002c61b },
		{ 0x000000000000141e, 0x06ea2e89 },
		{ 0x000000000000010a, 0xab002ad7 },
	}, {
		{ 0x0000017949e37538, 0x00000001 },
		{ 0x0000001b62441f37, 0x00000055 },
		{ 0x0000000694a3391d, 0x00000085 },
		{ 0x0000000010b2a5d2, 0x0000a753 },
		{ 0x000000000d4398ff, 0x00001ef9 },
		{ 0x0000000001882ec6, 0x0005cbf9 },
		{ 0x000000000035333b, 0x0017abdf },
		{ 0x00000000000129f1, 0x0ab4520d },
		{ 0x0000000000000f6e, 0x8ac0ce9b },
	}, {
		{ 0x000011f321a74e49, 0x00000006 },
		{ 0x0000014d8481d211, 0x0000005b },
		{ 0x0000005025cbd92d, 0x000001e3 },
		{ 0x00000000cb5e71e3, 0x000043e6 },
		{ 0x00000000a18c2ee1, 0x0000c097 },
		{ 0x0000000012a88828, 0x00036c97 },
		{ 0x000000000287f16f, 0x002c2a25 },
		{ 0x00000000000e2cc7, 0x02d581e3 },
		{ 0x000000000000bbf4, 0x1ba08c03 },
	}, {
		{ 0x0000d8db8f72935d, 0x00000005 },
		{ 0x00000fbd5aed7a2e, 0x00000002 },
		{ 0x000003c84b6ea64a, 0x00000122 },
		{ 0x0000000998fa8829, 0x000044b7 },
		{ 0x000000079fb80b07, 0x00002e4a },
		{ 0x00000000e16b20fa, 0x0002a14a },
		{ 0x000000001e940d22, 0x00353b2e },
		{ 0x0000000000ab40ac, 0x06fba6ba },
		{ 0x000000000008debd, 0x72d98365 },
	}, {
		{ 0x000cc3045b8fc281, 0x00000000 },
		{ 0x0000ed1f48b5c9fc, 0x00000079 },
		{ 0x000038fb9c63406a, 0x000000e1 },
		{ 0x000000909705b825, 0x00000a62 },
		{ 0x00000072db27380d, 0x0000d689 },
		{ 0x0000000d43fce827, 0x00082b09 },
		{ 0x00000001ccaba11a, 0x0037e8dd },
		{ 0x000000000a13f729, 0x0566dffd },
		{ 0x000000000085a14b, 0x23d36726 },
	}, {
		{ 0x00eafeb9c993592b, 0x00000001 },
		{ 0x00110e5befa9a991, 0x00000048 },
		{ 0x00041947b4a1d36a, 0x000000dc },
		{ 0x00000a6679327311, 0x0000c079 },
		{ 0x00000842f488162e, 0x00002284 },
		{ 0x000000f4459740fc, 0x00084484 },
		{ 0x0000002122c47bf9, 0x002ca446 },
		{ 0x00000000b9936290, 0x004979c4 },
		{ 0x00000000099ca89d, 0x9db446bf },
	}, {
		{ 0x1b60cece589da1d2, 0x00000001 },
		{ 0x01fcb42be1453f5b, 0x0000004f },
		{ 0x007a3f2457df0749, 0x0000013f },
		{ 0x0001363130e3ec7b, 0x000017aa },
		{ 0x0000f66745411d8a, 0x0000b063 },
		{ 0x00001c757dfab350, 0x00048863 },
		{ 0x000003dc4979c652, 0x00224ea7 },
		{ 0x000000159edc3144, 0x06409ab3 },
		{ 0x000000011eadfee3, 0xa99c48a8 },
	},
};

static inline bool test_div64_verify(u64 quotient, u32 remainder, int i, int j)
{
	return (quotient == test_div64_results[i][j].quotient &&
		remainder == test_div64_results[i][j].remainder);
}

/*
 * This needs to be a macro, because we don't want to rely on the compiler
 * to do constant propagation, and `do_div' may take a different path for
 * constants, so we do want to verify that as well.
 */
#define test_div64_one(divident, divisor, i, j) ({			\
	bool result = true;						\
	u64 quotient;							\
	u32 remainder;							\
									\
	quotient = divident;						\
	remainder = do_div(quotient, divisor);				\
	if (!test_div64_verify(quotient, remainder, i, j)) {		\
		pr_err("ERROR: %016llx / %08x => %016llx,%08x\n",	\
		       divident, divisor, quotient, remainder);		\
		pr_err("ERROR: expected value=> %016llx,%08x\n",	\
		       test_div64_results[i][j].quotient,		\
		       test_div64_results[i][j].remainder);		\
		result = false;						\
	}								\
	result;								\
})

/*
 * Run calculation for the same divisor value expressed as a constant
 * and as a variable, so as to verify the implementation for both cases
 * should they be handled by different code execution paths.
 */
static bool __init test_div64(void)
{
	u64 divident;
	int i, j;

	for (i = 0; i < SIZE_DIV64_DIVIDENTS; i++) {
		divident = test_div64_dividents[i];
		if (!test_div64_one(divident, TEST_DIV64_DIVISOR_0, i, 0))
			return false;
		if (!test_div64_one(divident, TEST_DIV64_DIVISOR_1, i, 1))
			return false;
		if (!test_div64_one(divident, TEST_DIV64_DIVISOR_2, i, 2))
			return false;
		if (!test_div64_one(divident, TEST_DIV64_DIVISOR_3, i, 3))
			return false;
		if (!test_div64_one(divident, TEST_DIV64_DIVISOR_4, i, 4))
			return false;
		if (!test_div64_one(divident, TEST_DIV64_DIVISOR_5, i, 5))
			return false;
		if (!test_div64_one(divident, TEST_DIV64_DIVISOR_6, i, 6))
			return false;
		if (!test_div64_one(divident, TEST_DIV64_DIVISOR_7, i, 7))
			return false;
		if (!test_div64_one(divident, TEST_DIV64_DIVISOR_8, i, 8))
			return false;
		for (j = 0; j < SIZE_DIV64_DIVISORS; j++) {
			if (!test_div64_one(divident, test_div64_divisors[j],
					    i, j))
				return false;
		}
	}
	return true;
}

static int __init test_div64_init(void)
{
	struct timespec64 ts, ts0, ts1;
	int i;

	pr_info("Starting 64bit/32bit division and modulo test\n");
	ktime_get_ts64(&ts0);

	for (i = 0; i < TEST_DIV64_N_ITER; i++)
		if (!test_div64())
			break;

	ktime_get_ts64(&ts1);
	ts = timespec64_sub(ts1, ts0);
	pr_info("Completed 64bit/32bit division and modulo test, "
		"%llu.%09lus elapsed\n", ts.tv_sec, ts.tv_nsec);

	return 0;
}

static void __exit test_div64_exit(void)
{
}

module_init(test_div64_init);
module_exit(test_div64_exit);

MODULE_AUTHOR("Maciej W. Rozycki <macro@orcam.me.uk>");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("64bit/32bit division and modulo test module");