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
19static 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
42static 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
55static 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
152static 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 */
186static 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
220static 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
240static void __exit test_div64_exit(void)
241{
242}
243
244module_init(test_div64_init);
245module_exit(test_div64_exit);
246
247MODULE_AUTHOR("Maciej W. Rozycki <macro@orcam.me.uk>");
248MODULE_LICENSE("GPL");
249MODULE_DESCRIPTION("64bit/32bit division and modulo test module");
250