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
250
251
252
253
254
255
256
257
|
// SPDX-License-Identifier: GPL-2.0-only
/*
* Test cases for <linux/hash.h> and <linux/stringhash.h>
* This just verifies that various ways of computing a hash
* produce the same thing and, for cases where a k-bit hash
* value is requested, is of the requested size.
*
* We fill a buffer with a 255-byte null-terminated string,
* and use both full_name_hash() and hashlen_string() to hash the
* substrings from i to j, where 0 <= i < j < 256.
*
* The returned values are used to check that __hash_32() and
* __hash_32_generic() compute the same thing. Likewise hash_32()
* and hash_64().
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt "\n"
#include <linux/compiler.h>
#include <linux/types.h>
#include <linux/module.h>
#include <linux/hash.h>
#include <linux/stringhash.h>
#include <linux/printk.h>
/* 32-bit XORSHIFT generator. Seed must not be zero. */
static u32 __init __attribute_const__
xorshift(u32 seed)
{
seed ^= seed << 13;
seed ^= seed >> 17;
seed ^= seed << 5;
return seed;
}
/* Given a non-zero x, returns a non-zero byte. */
static u8 __init __attribute_const__
mod255(u32 x)
{
x = (x & 0xffff) + (x >> 16); /* 1 <= x <= 0x1fffe */
x = (x & 0xff) + (x >> 8); /* 1 <= x <= 0x2fd */
x = (x & 0xff) + (x >> 8); /* 1 <= x <= 0x100 */
x = (x & 0xff) + (x >> 8); /* 1 <= x <= 0xff */
return x;
}
/* Fill the buffer with non-zero bytes. */
static void __init
fill_buf(char *buf, size_t len, u32 seed)
{
size_t i;
for (i = 0; i < len; i++) {
seed = xorshift(seed);
buf[i] = mod255(seed);
}
}
/*
* Test the various integer hash functions. h64 (or its low-order bits)
* is the integer to hash. hash_or accumulates the OR of the hash values,
* which are later checked to see that they cover all the requested bits.
*
* Because these functions (as opposed to the string hashes) are all
* inline, the code being tested is actually in the module, and you can
* recompile and re-test the module without rebooting.
*/
static bool __init
test_int_hash(unsigned long long h64, u32 hash_or[2][33])
{
int k;
u32 h0 = (u32)h64, h1, h2;
/* Test __hash32 */
hash_or[0][0] |= h1 = __hash_32(h0);
#ifdef HAVE_ARCH__HASH_32
hash_or[1][0] |= h2 = __hash_32_generic(h0);
#if HAVE_ARCH__HASH_32 == 1
if (h1 != h2) {
pr_err("__hash_32(%#x) = %#x != __hash_32_generic() = %#x",
h0, h1, h2);
return false;
}
#endif
#endif
/* Test k = 1..32 bits */
for (k = 1; k <= 32; k++) {
u32 const m = ((u32)2 << (k-1)) - 1; /* Low k bits set */
/* Test hash_32 */
hash_or[0][k] |= h1 = hash_32(h0, k);
if (h1 > m) {
pr_err("hash_32(%#x, %d) = %#x > %#x", h0, k, h1, m);
return false;
}
#ifdef HAVE_ARCH_HASH_32
h2 = hash_32_generic(h0, k);
#if HAVE_ARCH_HASH_32 == 1
if (h1 != h2) {
pr_err("hash_32(%#x, %d) = %#x != hash_32_generic() "
" = %#x", h0, k, h1, h2);
return false;
}
#else
if (h2 > m) {
pr_err("hash_32_generic(%#x, %d) = %#x > %#x",
h0, k, h1, m);
return false;
}
#endif
#endif
/* Test hash_64 */
hash_or[1][k] |= h1 = hash_64(h64, k);
if (h1 > m) {
pr_err("hash_64(%#llx, %d) = %#x > %#x", h64, k, h1, m);
return false;
}
#ifdef HAVE_ARCH_HASH_64
h2 = hash_64_generic(h64, k);
#if HAVE_ARCH_HASH_64 == 1
if (h1 != h2) {
pr_err("hash_64(%#llx, %d) = %#x != hash_64_generic() "
"= %#x", h64, k, h1, h2);
return false;
}
#else
if (h2 > m) {
pr_err("hash_64_generic(%#llx, %d) = %#x > %#x",
h64, k, h1, m);
return false;
}
#endif
#endif
}
(void)h2; /* Suppress unused variable warning */
return true;
}
#define SIZE 256 /* Run time is cubic in SIZE */
static int __init
test_hash_init(void)
{
char buf[SIZE+1];
u32 string_or = 0, hash_or[2][33] = { { 0, } };
unsigned tests = 0;
unsigned long long h64 = 0;
int i, j;
fill_buf(buf, SIZE, 1);
/* Test every possible non-empty substring in the buffer. */
for (j = SIZE; j > 0; --j) {
buf[j] = '\0';
for (i = 0; i <= j; i++) {
u64 hashlen = hashlen_string(buf+i, buf+i);
u32 h0 = full_name_hash(buf+i, buf+i, j-i);
/* Check that hashlen_string gets the length right */
if (hashlen_len(hashlen) != j-i) {
pr_err("hashlen_string(%d..%d) returned length"
" %u, expected %d",
i, j, hashlen_len(hashlen), j-i);
return -EINVAL;
}
/* Check that the hashes match */
if (hashlen_hash(hashlen) != h0) {
pr_err("hashlen_string(%d..%d) = %08x != "
"full_name_hash() = %08x",
i, j, hashlen_hash(hashlen), h0);
return -EINVAL;
}
string_or |= h0;
h64 = h64 << 32 | h0; /* For use with hash_64 */
if (!test_int_hash(h64, hash_or))
return -EINVAL;
tests++;
} /* i */
} /* j */
/* The OR of all the hash values should cover all the bits */
if (~string_or) {
pr_err("OR of all string hash results = %#x != %#x",
string_or, -1u);
return -EINVAL;
}
if (~hash_or[0][0]) {
pr_err("OR of all __hash_32 results = %#x != %#x",
hash_or[0][0], -1u);
return -EINVAL;
}
#ifdef HAVE_ARCH__HASH_32
#if HAVE_ARCH__HASH_32 != 1 /* Test is pointless if results match */
if (~hash_or[1][0]) {
pr_err("OR of all __hash_32_generic results = %#x != %#x",
hash_or[1][0], -1u);
return -EINVAL;
}
#endif
#endif
/* Likewise for all the i-bit hash values */
for (i = 1; i <= 32; i++) {
u32 const m = ((u32)2 << (i-1)) - 1; /* Low i bits set */
if (hash_or[0][i] != m) {
pr_err("OR of all hash_32(%d) results = %#x "
"(%#x expected)", i, hash_or[0][i], m);
return -EINVAL;
}
if (hash_or[1][i] != m) {
pr_err("OR of all hash_64(%d) results = %#x "
"(%#x expected)", i, hash_or[1][i], m);
return -EINVAL;
}
}
/* Issue notices about skipped tests. */
#ifdef HAVE_ARCH__HASH_32
#if HAVE_ARCH__HASH_32 != 1
pr_info("__hash_32() is arch-specific; not compared to generic.");
#endif
#else
pr_info("__hash_32() has no arch implementation to test.");
#endif
#ifdef HAVE_ARCH_HASH_32
#if HAVE_ARCH_HASH_32 != 1
pr_info("hash_32() is arch-specific; not compared to generic.");
#endif
#else
pr_info("hash_32() has no arch implementation to test.");
#endif
#ifdef HAVE_ARCH_HASH_64
#if HAVE_ARCH_HASH_64 != 1
pr_info("hash_64() is arch-specific; not compared to generic.");
#endif
#else
pr_info("hash_64() has no arch implementation to test.");
#endif
pr_notice("%u tests passed.", tests);
return 0;
}
static void __exit test_hash_exit(void)
{
}
module_init(test_hash_init); /* Does everything */
module_exit(test_hash_exit); /* Does nothing */
MODULE_LICENSE("GPL");
|
