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__
xorshift(u32 seed)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__
mod255(u32 x)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. */
fill_buf(char * buf,size_t len,u32 seed)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
test_int__hash_32(struct kunit * test,struct test_hash_params * params)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
test_int_hash_64(struct kunit * test,struct test_hash_params * params,u32 const * m,int * k)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
test_int_hash(struct kunit * test,unsigned long long h64,u32 hash_or[2][33])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, &params);
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, &params, &m, &k);
138 #endif
139 	}
140 }
141 
142 #define SIZE 256	/* Run time is cubic in SIZE */
143 
test_string_or(struct kunit * test)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 
test_hash_or(struct kunit * test)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_LICENSE("GPL");
239