1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Copyright (C) 2024 BayLibre SAS
4 */
5
6 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
7
8 #include <linux/init.h>
9 #include <linux/module.h>
10 #include <linux/printk.h>
11 #include <linux/math64.h>
12
13 typedef struct { u64 a; u64 b; u64 c; u64 result; } test_params;
14
15 static test_params test_values[] = {
16 /* this contains many edge values followed by a couple random values */
17 { 0xb, 0x7, 0x3, 0x19 },
18 { 0xffff0000, 0xffff0000, 0xf, 0x1110eeef00000000 },
19 { 0xffffffff, 0xffffffff, 0x1, 0xfffffffe00000001 },
20 { 0xffffffff, 0xffffffff, 0x2, 0x7fffffff00000000 },
21 { 0x1ffffffff, 0xffffffff, 0x2, 0xfffffffe80000000 },
22 { 0x1ffffffff, 0xffffffff, 0x3, 0xaaaaaaa9aaaaaaab },
23 { 0x1ffffffff, 0x1ffffffff, 0x4, 0xffffffff00000000 },
24 { 0xffff000000000000, 0xffff000000000000, 0xffff000000000001, 0xfffeffffffffffff },
25 { 0x3333333333333333, 0x3333333333333333, 0x5555555555555555, 0x1eb851eb851eb851 },
26 { 0x7fffffffffffffff, 0x2, 0x3, 0x5555555555555554 },
27 { 0xffffffffffffffff, 0x2, 0x8000000000000000, 0x3 },
28 { 0xffffffffffffffff, 0x2, 0xc000000000000000, 0x2 },
29 { 0xffffffffffffffff, 0x4000000000000004, 0x8000000000000000, 0x8000000000000007 },
30 { 0xffffffffffffffff, 0x4000000000000001, 0x8000000000000000, 0x8000000000000001 },
31 { 0xffffffffffffffff, 0x8000000000000001, 0xffffffffffffffff, 0x8000000000000001 },
32 { 0xfffffffffffffffe, 0x8000000000000001, 0xffffffffffffffff, 0x8000000000000000 },
33 { 0xffffffffffffffff, 0x8000000000000001, 0xfffffffffffffffe, 0x8000000000000001 },
34 { 0xffffffffffffffff, 0x8000000000000001, 0xfffffffffffffffd, 0x8000000000000002 },
35 { 0x7fffffffffffffff, 0xffffffffffffffff, 0xc000000000000000, 0xaaaaaaaaaaaaaaa8 },
36 { 0xffffffffffffffff, 0x7fffffffffffffff, 0xa000000000000000, 0xccccccccccccccca },
37 { 0xffffffffffffffff, 0x7fffffffffffffff, 0x9000000000000000, 0xe38e38e38e38e38b },
38 { 0x7fffffffffffffff, 0x7fffffffffffffff, 0x5000000000000000, 0xccccccccccccccc9 },
39 { 0xffffffffffffffff, 0xfffffffffffffffe, 0xffffffffffffffff, 0xfffffffffffffffe },
40 { 0xe6102d256d7ea3ae, 0x70a77d0be4c31201, 0xd63ec35ab3220357, 0x78f8bf8cc86c6e18 },
41 { 0xf53bae05cb86c6e1, 0x3847b32d2f8d32e0, 0xcfd4f55a647f403c, 0x42687f79d8998d35 },
42 { 0x9951c5498f941092, 0x1f8c8bfdf287a251, 0xa3c8dc5f81ea3fe2, 0x1d887cb25900091f },
43 { 0x374fee9daa1bb2bb, 0x0d0bfbff7b8ae3ef, 0xc169337bd42d5179, 0x03bb2dbaffcbb961 },
44 { 0xeac0d03ac10eeaf0, 0x89be05dfa162ed9b, 0x92bb1679a41f0e4b, 0xdc5f5cc9e270d216 },
45 };
46
47 /*
48 * The above table can be verified with the following shell script:
49 *
50 * #!/bin/sh
51 * sed -ne 's/^{ \+\(.*\), \+\(.*\), \+\(.*\), \+\(.*\) },$/\1 \2 \3 \4/p' \
52 * lib/math/test_mul_u64_u64_div_u64.c |
53 * while read a b c r; do
54 * expected=$( printf "obase=16; ibase=16; %X * %X / %X\n" $a $b $c | bc )
55 * given=$( printf "%X\n" $r )
56 * if [ "$expected" = "$given" ]; then
57 * echo "$a * $b / $c = $r OK"
58 * else
59 * echo "$a * $b / $c = $r is wrong" >&2
60 * echo "should be equivalent to 0x$expected" >&2
61 * exit 1
62 * fi
63 * done
64 */
65
66 static int __init test_init(void)
67 {
68 int i;
69
70 pr_info("Starting mul_u64_u64_div_u64() test\n");
71
72 for (i = 0; i < ARRAY_SIZE(test_values); i++) {
73 u64 a = test_values[i].a;
74 u64 b = test_values[i].b;
75 u64 c = test_values[i].c;
76 u64 expected_result = test_values[i].result;
77 u64 result = mul_u64_u64_div_u64(a, b, c);
78
79 if (result != expected_result) {
80 pr_err("ERROR: 0x%016llx * 0x%016llx / 0x%016llx\n", a, b, c);
81 pr_err("ERROR: expected result: %016llx\n", expected_result);
82 pr_err("ERROR: obtained result: %016llx\n", result);
83 }
84 }
85
86 pr_info("Completed mul_u64_u64_div_u64() test\n");
87 return 0;
88 }
89
90 static void __exit test_exit(void)
91 {
92 }
93
94 module_init(test_init);
95 module_exit(test_exit);
96
97 MODULE_AUTHOR("Nicolas Pitre");
98 MODULE_LICENSE("GPL");
99 MODULE_DESCRIPTION("mul_u64_u64_div_u64() test module");
100
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