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