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 #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]; 147 u32 string_or = 0, hash_or[2][33] = { { 0, } }; 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++) { 159 u64 hashlen = hashlen_string(buf+i, buf+i); 160 u32 h0 = full_name_hash(buf+i, buf+i, j-i); 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. */ 223 #ifdef HAVE_ARCH__HASH_32 224 #if HAVE_ARCH__HASH_32 != 1 225 pr_info("__hash_32() is arch-specific; not compared to generic."); 226 #endif 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 != 1 232 pr_info("hash_32() is arch-specific; not compared to generic."); 233 #endif 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 != 1 239 pr_info("hash_64() is arch-specific; not compared to generic."); 240 #endif 241 #else 242 pr_info("hash_64() has no arch implementation to test."); 243 #endif 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"); 258