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09c434b8 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
468a9428 GS |
2 | /* |
3 | * Test cases for <linux/hash.h> and <linux/stringhash.h> | |
4 | * This just verifies that various ways of computing a hash | |
5 | * produce the same thing and, for cases where a k-bit hash | |
6 | * value is requested, is of the requested size. | |
7 | * | |
8 | * We fill a buffer with a 255-byte null-terminated string, | |
9 | * and use both full_name_hash() and hashlen_string() to hash the | |
10 | * substrings from i to j, where 0 <= i < j < 256. | |
11 | * | |
12 | * The returned values are used to check that __hash_32() and | |
13 | * __hash_32_generic() compute the same thing. Likewise hash_32() | |
14 | * and hash_64(). | |
15 | */ | |
16 | ||
17 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt "\n" | |
18 | ||
19 | #include <linux/compiler.h> | |
20 | #include <linux/types.h> | |
21 | #include <linux/module.h> | |
22 | #include <linux/hash.h> | |
23 | #include <linux/stringhash.h> | |
24 | #include <linux/printk.h> | |
25 | ||
26 | /* 32-bit XORSHIFT generator. Seed must not be zero. */ | |
27 | static u32 __init __attribute_const__ | |
28 | xorshift(u32 seed) | |
29 | { | |
30 | seed ^= seed << 13; | |
31 | seed ^= seed >> 17; | |
32 | seed ^= seed << 5; | |
33 | return seed; | |
34 | } | |
35 | ||
36 | /* Given a non-zero x, returns a non-zero byte. */ | |
37 | static u8 __init __attribute_const__ | |
38 | mod255(u32 x) | |
39 | { | |
40 | x = (x & 0xffff) + (x >> 16); /* 1 <= x <= 0x1fffe */ | |
41 | x = (x & 0xff) + (x >> 8); /* 1 <= x <= 0x2fd */ | |
42 | x = (x & 0xff) + (x >> 8); /* 1 <= x <= 0x100 */ | |
43 | x = (x & 0xff) + (x >> 8); /* 1 <= x <= 0xff */ | |
44 | return x; | |
45 | } | |
46 | ||
47 | /* Fill the buffer with non-zero bytes. */ | |
48 | static void __init | |
49 | fill_buf(char *buf, size_t len, u32 seed) | |
50 | { | |
51 | size_t i; | |
52 | ||
53 | for (i = 0; i < len; i++) { | |
54 | seed = xorshift(seed); | |
55 | buf[i] = mod255(seed); | |
56 | } | |
57 | } | |
58 | ||
59 | /* | |
60 | * Test the various integer hash functions. h64 (or its low-order bits) | |
61 | * is the integer to hash. hash_or accumulates the OR of the hash values, | |
62 | * which are later checked to see that they cover all the requested bits. | |
63 | * | |
64 | * Because these functions (as opposed to the string hashes) are all | |
65 | * inline, the code being tested is actually in the module, and you can | |
66 | * recompile and re-test the module without rebooting. | |
67 | */ | |
68 | static bool __init | |
69 | test_int_hash(unsigned long long h64, u32 hash_or[2][33]) | |
70 | { | |
71 | int k; | |
72 | u32 h0 = (u32)h64, h1, h2; | |
73 | ||
74 | /* Test __hash32 */ | |
75 | hash_or[0][0] |= h1 = __hash_32(h0); | |
76 | #ifdef HAVE_ARCH__HASH_32 | |
77 | hash_or[1][0] |= h2 = __hash_32_generic(h0); | |
78 | #if HAVE_ARCH__HASH_32 == 1 | |
79 | if (h1 != h2) { | |
80 | pr_err("__hash_32(%#x) = %#x != __hash_32_generic() = %#x", | |
81 | h0, h1, h2); | |
82 | return false; | |
83 | } | |
84 | #endif | |
85 | #endif | |
86 | ||
87 | /* Test k = 1..32 bits */ | |
88 | for (k = 1; k <= 32; k++) { | |
89 | u32 const m = ((u32)2 << (k-1)) - 1; /* Low k bits set */ | |
90 | ||
91 | /* Test hash_32 */ | |
92 | hash_or[0][k] |= h1 = hash_32(h0, k); | |
93 | if (h1 > m) { | |
94 | pr_err("hash_32(%#x, %d) = %#x > %#x", h0, k, h1, m); | |
95 | return false; | |
96 | } | |
97 | #ifdef HAVE_ARCH_HASH_32 | |
98 | h2 = hash_32_generic(h0, k); | |
99 | #if HAVE_ARCH_HASH_32 == 1 | |
100 | if (h1 != h2) { | |
101 | pr_err("hash_32(%#x, %d) = %#x != hash_32_generic() " | |
102 | " = %#x", h0, k, h1, h2); | |
103 | return false; | |
104 | } | |
105 | #else | |
106 | if (h2 > m) { | |
107 | pr_err("hash_32_generic(%#x, %d) = %#x > %#x", | |
108 | h0, k, h1, m); | |
109 | return false; | |
110 | } | |
111 | #endif | |
112 | #endif | |
113 | /* Test hash_64 */ | |
114 | hash_or[1][k] |= h1 = hash_64(h64, k); | |
115 | if (h1 > m) { | |
116 | pr_err("hash_64(%#llx, %d) = %#x > %#x", h64, k, h1, m); | |
117 | return false; | |
118 | } | |
119 | #ifdef HAVE_ARCH_HASH_64 | |
120 | h2 = hash_64_generic(h64, k); | |
121 | #if HAVE_ARCH_HASH_64 == 1 | |
122 | if (h1 != h2) { | |
123 | pr_err("hash_64(%#llx, %d) = %#x != hash_64_generic() " | |
124 | "= %#x", h64, k, h1, h2); | |
125 | return false; | |
126 | } | |
127 | #else | |
128 | if (h2 > m) { | |
129 | pr_err("hash_64_generic(%#llx, %d) = %#x > %#x", | |
130 | h64, k, h1, m); | |
131 | return false; | |
132 | } | |
133 | #endif | |
134 | #endif | |
135 | } | |
136 | ||
137 | (void)h2; /* Suppress unused variable warning */ | |
138 | return true; | |
139 | } | |
140 | ||
141 | #define SIZE 256 /* Run time is cubic in SIZE */ | |
142 | ||
143 | static int __init | |
144 | test_hash_init(void) | |
145 | { | |
146 | char buf[SIZE+1]; | |
ed76b7a1 | 147 | u32 string_or = 0, hash_or[2][33] = { { 0, } }; |
468a9428 GS |
148 | unsigned tests = 0; |
149 | unsigned long long h64 = 0; | |
150 | int i, j; | |
151 | ||
152 | fill_buf(buf, SIZE, 1); | |
153 | ||
154 | /* Test every possible non-empty substring in the buffer. */ | |
155 | for (j = SIZE; j > 0; --j) { | |
156 | buf[j] = '\0'; | |
157 | ||
158 | for (i = 0; i <= j; i++) { | |
8387ff25 LT |
159 | u64 hashlen = hashlen_string(buf+i, buf+i); |
160 | u32 h0 = full_name_hash(buf+i, buf+i, j-i); | |
468a9428 GS |
161 | |
162 | /* Check that hashlen_string gets the length right */ | |
163 | if (hashlen_len(hashlen) != j-i) { | |
164 | pr_err("hashlen_string(%d..%d) returned length" | |
165 | " %u, expected %d", | |
166 | i, j, hashlen_len(hashlen), j-i); | |
167 | return -EINVAL; | |
168 | } | |
169 | /* Check that the hashes match */ | |
170 | if (hashlen_hash(hashlen) != h0) { | |
171 | pr_err("hashlen_string(%d..%d) = %08x != " | |
172 | "full_name_hash() = %08x", | |
173 | i, j, hashlen_hash(hashlen), h0); | |
174 | return -EINVAL; | |
175 | } | |
176 | ||
177 | string_or |= h0; | |
178 | h64 = h64 << 32 | h0; /* For use with hash_64 */ | |
179 | if (!test_int_hash(h64, hash_or)) | |
180 | return -EINVAL; | |
181 | tests++; | |
182 | } /* i */ | |
183 | } /* j */ | |
184 | ||
185 | /* The OR of all the hash values should cover all the bits */ | |
186 | if (~string_or) { | |
187 | pr_err("OR of all string hash results = %#x != %#x", | |
188 | string_or, -1u); | |
189 | return -EINVAL; | |
190 | } | |
191 | if (~hash_or[0][0]) { | |
192 | pr_err("OR of all __hash_32 results = %#x != %#x", | |
193 | hash_or[0][0], -1u); | |
194 | return -EINVAL; | |
195 | } | |
196 | #ifdef HAVE_ARCH__HASH_32 | |
197 | #if HAVE_ARCH__HASH_32 != 1 /* Test is pointless if results match */ | |
198 | if (~hash_or[1][0]) { | |
199 | pr_err("OR of all __hash_32_generic results = %#x != %#x", | |
200 | hash_or[1][0], -1u); | |
201 | return -EINVAL; | |
202 | } | |
203 | #endif | |
204 | #endif | |
205 | ||
206 | /* Likewise for all the i-bit hash values */ | |
207 | for (i = 1; i <= 32; i++) { | |
208 | u32 const m = ((u32)2 << (i-1)) - 1; /* Low i bits set */ | |
209 | ||
210 | if (hash_or[0][i] != m) { | |
211 | pr_err("OR of all hash_32(%d) results = %#x " | |
212 | "(%#x expected)", i, hash_or[0][i], m); | |
213 | return -EINVAL; | |
214 | } | |
215 | if (hash_or[1][i] != m) { | |
216 | pr_err("OR of all hash_64(%d) results = %#x " | |
217 | "(%#x expected)", i, hash_or[1][i], m); | |
218 | return -EINVAL; | |
219 | } | |
220 | } | |
221 | ||
222 | /* Issue notices about skipped tests. */ | |
e6173ba4 GU |
223 | #ifdef HAVE_ARCH__HASH_32 |
224 | #if HAVE_ARCH__HASH_32 != 1 | |
468a9428 GS |
225 | pr_info("__hash_32() is arch-specific; not compared to generic."); |
226 | #endif | |
e6173ba4 GU |
227 | #else |
228 | pr_info("__hash_32() has no arch implementation to test."); | |
229 | #endif | |
230 | #ifdef HAVE_ARCH_HASH_32 | |
231 | #if HAVE_ARCH_HASH_32 != 1 | |
468a9428 GS |
232 | pr_info("hash_32() is arch-specific; not compared to generic."); |
233 | #endif | |
e6173ba4 GU |
234 | #else |
235 | pr_info("hash_32() has no arch implementation to test."); | |
236 | #endif | |
237 | #ifdef HAVE_ARCH_HASH_64 | |
238 | #if HAVE_ARCH_HASH_64 != 1 | |
468a9428 GS |
239 | pr_info("hash_64() is arch-specific; not compared to generic."); |
240 | #endif | |
e6173ba4 GU |
241 | #else |
242 | pr_info("hash_64() has no arch implementation to test."); | |
243 | #endif | |
468a9428 GS |
244 | |
245 | pr_notice("%u tests passed.", tests); | |
246 | ||
247 | return 0; | |
248 | } | |
249 | ||
250 | static void __exit test_hash_exit(void) | |
251 | { | |
252 | } | |
253 | ||
254 | module_init(test_hash_init); /* Does everything */ | |
255 | module_exit(test_hash_exit); /* Does nothing */ | |
256 | ||
257 | MODULE_LICENSE("GPL"); |