1 // SPDX-License-Identifier: GPL-2.0-only
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 #include <linux/compiler.h>
18 #include <linux/types.h>
19 #include <linux/module.h>
20 #include <linux/hash.h>
21 #include <linux/stringhash.h>
22 #include <kunit/test.h>
23
24 /* 32-bit XORSHIFT generator. Seed must not be zero. */
25 static u32 __attribute_const__
26 xorshift(u32 seed)
27 {
28 seed ^= seed << 13;
29 seed ^= seed >> 17;
30 seed ^= seed << 5;
31 return seed;
32 }
33
34 /* Given a non-zero x, returns a non-zero byte. */
35 static u8 __attribute_const__
36 mod255(u32 x)
37 {
38 x = (x & 0xffff) + (x >> 16); /* 1 <= x <= 0x1fffe */
39 x = (x & 0xff) + (x >> 8); /* 1 <= x <= 0x2fd */
40 x = (x & 0xff) + (x >> 8); /* 1 <= x <= 0x100 */
41 x = (x & 0xff) + (x >> 8); /* 1 <= x <= 0xff */
42 return x;
43 }
44
45 /* Fill the buffer with non-zero bytes. */
46 static void fill_buf(char *buf, size_t len, u32 seed)
47 {
48 size_t i;
49
50 for (i = 0; i < len; i++) {
51 seed = xorshift(seed);
52 buf[i] = mod255(seed);
53 }
54 }
55
56 /* Holds most testing variables for the int test. */
57 struct test_hash_params {
58 /* Pointer to integer to be hashed. */
59 unsigned long long *h64;
60 /* Low 32-bits of integer to be hashed. */
61 u32 h0;
62 /* Arch-specific hash result. */
63 u32 h1;
64 /* Generic hash result. */
65 u32 h2;
66 /* ORed hashes of given size (in bits). */
67 u32 (*hash_or)[33];
68 };
69
70 #ifdef HAVE_ARCH__HASH_32
71 static void
72 test_int__hash_32(struct kunit *test, struct test_hash_params *params)
73 {
74 params->hash_or[1][0] |= params->h2 = __hash_32_generic(params->h0);
75 #if HAVE_ARCH__HASH_32 == 1
76 KUNIT_EXPECT_EQ_MSG(test, params->h1, params->h2,
77 "__hash_32(%#x) = %#x != __hash_32_generic() = %#x",
78 params->h0, params->h1, params->h2);
79 #endif
80 }
81 #endif
82
83 #ifdef HAVE_ARCH_HASH_64
84 static void
85 test_int_hash_64(struct kunit *test, struct test_hash_params *params, u32 const *m, int *k)
86 {
87 params->h2 = hash_64_generic(*params->h64, *k);
88 #if HAVE_ARCH_HASH_64 == 1
89 KUNIT_EXPECT_EQ_MSG(test, params->h1, params->h2,
90 "hash_64(%#llx, %d) = %#x != hash_64_generic() = %#x",
91 *params->h64, *k, params->h1, params->h2);
92 #else
93 KUNIT_EXPECT_LE_MSG(test, params->h1, params->h2,
94 "hash_64_generic(%#llx, %d) = %#x > %#x",
95 *params->h64, *k, params->h1, *m);
96 #endif
97 }
98 #endif
99
100 /*
101 * Test the various integer hash functions. h64 (or its low-order bits)
102 * is the integer to hash. hash_or accumulates the OR of the hash values,
103 * which are later checked to see that they cover all the requested bits.
104 *
105 * Because these functions (as opposed to the string hashes) are all
106 * inline, the code being tested is actually in the module, and you can
107 * recompile and re-test the module without rebooting.
108 */
109 static void
110 test_int_hash(struct kunit *test, unsigned long long h64, u32 hash_or[2][33])
111 {
112 int k;
113 struct test_hash_params params = { &h64, (u32)h64, 0, 0, hash_or };
114
115 /* Test __hash32 */
116 hash_or[0][0] |= params.h1 = __hash_32(params.h0);
117 #ifdef HAVE_ARCH__HASH_32
118 test_int__hash_32(test, ¶ms);
119 #endif
120
121 /* Test k = 1..32 bits */
122 for (k = 1; k <= 32; k++) {
123 u32 const m = ((u32)2 << (k-1)) - 1; /* Low k bits set */
124
125 /* Test hash_32 */
126 hash_or[0][k] |= params.h1 = hash_32(params.h0, k);
127 KUNIT_EXPECT_LE_MSG(test, params.h1, m,
128 "hash_32(%#x, %d) = %#x > %#x",
129 params.h0, k, params.h1, m);
130
131 /* Test hash_64 */
132 hash_or[1][k] |= params.h1 = hash_64(h64, k);
133 KUNIT_EXPECT_LE_MSG(test, params.h1, m,
134 "hash_64(%#llx, %d) = %#x > %#x",
135 h64, k, params.h1, m);
136 #ifdef HAVE_ARCH_HASH_64
137 test_int_hash_64(test, ¶ms, &m, &k);
138 #endif
139 }
140 }
141
142 #define SIZE 256 /* Run time is cubic in SIZE */
143
144 static void test_string_or(struct kunit *test)
145 {
146 char buf[SIZE+1];
147 u32 string_or = 0;
148 int i, j;
149
150 fill_buf(buf, SIZE, 1);
151
152 /* Test every possible non-empty substring in the buffer. */
153 for (j = SIZE; j > 0; --j) {
154 buf[j] = '\0';
155
156 for (i = 0; i <= j; i++) {
157 u32 h0 = full_name_hash(buf+i, buf+i, j-i);
158
159 string_or |= h0;
160 } /* i */
161 } /* j */
162
163 /* The OR of all the hash values should cover all the bits */
164 KUNIT_EXPECT_EQ_MSG(test, string_or, -1u,
165 "OR of all string hash results = %#x != %#x",
166 string_or, -1u);
167 }
168
169 static void test_hash_or(struct kunit *test)
170 {
171 char buf[SIZE+1];
172 u32 hash_or[2][33] = { { 0, } };
173 unsigned long long h64 = 0;
174 int i, j;
175
176 fill_buf(buf, SIZE, 1);
177
178 /* Test every possible non-empty substring in the buffer. */
179 for (j = SIZE; j > 0; --j) {
180 buf[j] = '\0';
181
182 for (i = 0; i <= j; i++) {
183 u64 hashlen = hashlen_string(buf+i, buf+i);
184 u32 h0 = full_name_hash(buf+i, buf+i, j-i);
185
186 /* Check that hashlen_string gets the length right */
187 KUNIT_EXPECT_EQ_MSG(test, hashlen_len(hashlen), j-i,
188 "hashlen_string(%d..%d) returned length %u, expected %d",
189 i, j, hashlen_len(hashlen), j-i);
190 /* Check that the hashes match */
191 KUNIT_EXPECT_EQ_MSG(test, hashlen_hash(hashlen), h0,
192 "hashlen_string(%d..%d) = %08x != full_name_hash() = %08x",
193 i, j, hashlen_hash(hashlen), h0);
194
195 h64 = h64 << 32 | h0; /* For use with hash_64 */
196 test_int_hash(test, h64, hash_or);
197 } /* i */
198 } /* j */
199
200 KUNIT_EXPECT_EQ_MSG(test, hash_or[0][0], -1u,
201 "OR of all __hash_32 results = %#x != %#x",
202 hash_or[0][0], -1u);
203 #ifdef HAVE_ARCH__HASH_32
204 #if HAVE_ARCH__HASH_32 != 1 /* Test is pointless if results match */
205 KUNIT_EXPECT_EQ_MSG(test, hash_or[1][0], -1u,
206 "OR of all __hash_32_generic results = %#x != %#x",
207 hash_or[1][0], -1u);
208 #endif
209 #endif
210
211 /* Likewise for all the i-bit hash values */
212 for (i = 1; i <= 32; i++) {
213 u32 const m = ((u32)2 << (i-1)) - 1; /* Low i bits set */
214
215 KUNIT_EXPECT_EQ_MSG(test, hash_or[0][i], m,
216 "OR of all hash_32(%d) results = %#x (%#x expected)",
217 i, hash_or[0][i], m);
218 KUNIT_EXPECT_EQ_MSG(test, hash_or[1][i], m,
219 "OR of all hash_64(%d) results = %#x (%#x expected)",
220 i, hash_or[1][i], m);
221 }
222 }
223
224 static struct kunit_case hash_test_cases[] __refdata = {
225 KUNIT_CASE(test_string_or),
226 KUNIT_CASE(test_hash_or),
227 {}
228 };
229
230 static struct kunit_suite hash_test_suite = {
231 .name = "hash",
232 .test_cases = hash_test_cases,
233 };
234
235
236 kunit_test_suite(hash_test_suite);
237
238 MODULE_DESCRIPTION("Test cases for <linux/hash.h> and <linux/stringhash.h>");
239 MODULE_LICENSE("GPL");
240
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