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Diffstat (limited to 'lib/test_hash.c')
| -rw-r--r-- | lib/test_hash.c | 238 |
1 files changed, 238 insertions, 0 deletions
diff --git a/lib/test_hash.c b/lib/test_hash.c new file mode 100644 index 000000000..bb25fda34 --- /dev/null +++ b/lib/test_hash.c @@ -0,0 +1,238 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Test cases for <linux/hash.h> and <linux/stringhash.h> + * This just verifies that various ways of computing a hash + * produce the same thing and, for cases where a k-bit hash + * value is requested, is of the requested size. + * + * We fill a buffer with a 255-byte null-terminated string, + * and use both full_name_hash() and hashlen_string() to hash the + * substrings from i to j, where 0 <= i < j < 256. + * + * The returned values are used to check that __hash_32() and + * __hash_32_generic() compute the same thing. Likewise hash_32() + * and hash_64(). + */ + +#include <linux/compiler.h> +#include <linux/types.h> +#include <linux/module.h> +#include <linux/hash.h> +#include <linux/stringhash.h> +#include <kunit/test.h> + +/* 32-bit XORSHIFT generator. Seed must not be zero. */ +static u32 __attribute_const__ +xorshift(u32 seed) +{ + seed ^= seed << 13; + seed ^= seed >> 17; + seed ^= seed << 5; + return seed; +} + +/* Given a non-zero x, returns a non-zero byte. */ +static u8 __attribute_const__ +mod255(u32 x) +{ + x = (x & 0xffff) + (x >> 16); /* 1 <= x <= 0x1fffe */ + x = (x & 0xff) + (x >> 8); /* 1 <= x <= 0x2fd */ + x = (x & 0xff) + (x >> 8); /* 1 <= x <= 0x100 */ + x = (x & 0xff) + (x >> 8); /* 1 <= x <= 0xff */ + return x; +} + +/* Fill the buffer with non-zero bytes. */ +static void fill_buf(char *buf, size_t len, u32 seed) +{ + size_t i; + + for (i = 0; i < len; i++) { + seed = xorshift(seed); + buf[i] = mod255(seed); + } +} + +/* Holds most testing variables for the int test. */ +struct test_hash_params { + /* Pointer to integer to be hashed. */ + unsigned long long *h64; + /* Low 32-bits of integer to be hashed. */ + u32 h0; + /* Arch-specific hash result. */ + u32 h1; + /* Generic hash result. */ + u32 h2; + /* ORed hashes of given size (in bits). */ + u32 (*hash_or)[33]; +}; + +#ifdef HAVE_ARCH__HASH_32 +static void +test_int__hash_32(struct kunit *test, struct test_hash_params *params) +{ + params->hash_or[1][0] |= params->h2 = __hash_32_generic(params->h0); +#if HAVE_ARCH__HASH_32 == 1 + KUNIT_EXPECT_EQ_MSG(test, params->h1, params->h2, + "__hash_32(%#x) = %#x != __hash_32_generic() = %#x", + params->h0, params->h1, params->h2); +#endif +} +#endif + +#ifdef HAVE_ARCH_HASH_64 +static void +test_int_hash_64(struct kunit *test, struct test_hash_params *params, u32 const *m, int *k) +{ + params->h2 = hash_64_generic(*params->h64, *k); +#if HAVE_ARCH_HASH_64 == 1 + KUNIT_EXPECT_EQ_MSG(test, params->h1, params->h2, + "hash_64(%#llx, %d) = %#x != hash_64_generic() = %#x", + *params->h64, *k, params->h1, params->h2); +#else + KUNIT_EXPECT_LE_MSG(test, params->h1, params->h2, + "hash_64_generic(%#llx, %d) = %#x > %#x", + *params->h64, *k, params->h1, *m); +#endif +} +#endif + +/* + * Test the various integer hash functions. h64 (or its low-order bits) + * is the integer to hash. hash_or accumulates the OR of the hash values, + * which are later checked to see that they cover all the requested bits. + * + * Because these functions (as opposed to the string hashes) are all + * inline, the code being tested is actually in the module, and you can + * recompile and re-test the module without rebooting. + */ +static void +test_int_hash(struct kunit *test, unsigned long long h64, u32 hash_or[2][33]) +{ + int k; + struct test_hash_params params = { &h64, (u32)h64, 0, 0, hash_or }; + + /* Test __hash32 */ + hash_or[0][0] |= params.h1 = __hash_32(params.h0); +#ifdef HAVE_ARCH__HASH_32 + test_int__hash_32(test, ¶ms); +#endif + + /* Test k = 1..32 bits */ + for (k = 1; k <= 32; k++) { + u32 const m = ((u32)2 << (k-1)) - 1; /* Low k bits set */ + + /* Test hash_32 */ + hash_or[0][k] |= params.h1 = hash_32(params.h0, k); + KUNIT_EXPECT_LE_MSG(test, params.h1, m, + "hash_32(%#x, %d) = %#x > %#x", + params.h0, k, params.h1, m); + + /* Test hash_64 */ + hash_or[1][k] |= params.h1 = hash_64(h64, k); + KUNIT_EXPECT_LE_MSG(test, params.h1, m, + "hash_64(%#llx, %d) = %#x > %#x", + h64, k, params.h1, m); +#ifdef HAVE_ARCH_HASH_64 + test_int_hash_64(test, ¶ms, &m, &k); +#endif + } +} + +#define SIZE 256 /* Run time is cubic in SIZE */ + +static void test_string_or(struct kunit *test) +{ + char buf[SIZE+1]; + u32 string_or = 0; + int i, j; + + fill_buf(buf, SIZE, 1); + + /* Test every possible non-empty substring in the buffer. */ + for (j = SIZE; j > 0; --j) { + buf[j] = '\0'; + + for (i = 0; i <= j; i++) { + u32 h0 = full_name_hash(buf+i, buf+i, j-i); + + string_or |= h0; + } /* i */ + } /* j */ + + /* The OR of all the hash values should cover all the bits */ + KUNIT_EXPECT_EQ_MSG(test, string_or, -1u, + "OR of all string hash results = %#x != %#x", + string_or, -1u); +} + +static void test_hash_or(struct kunit *test) +{ + char buf[SIZE+1]; + u32 hash_or[2][33] = { { 0, } }; + unsigned long long h64 = 0; + int i, j; + + fill_buf(buf, SIZE, 1); + + /* Test every possible non-empty substring in the buffer. */ + for (j = SIZE; j > 0; --j) { + buf[j] = '\0'; + + for (i = 0; i <= j; i++) { + u64 hashlen = hashlen_string(buf+i, buf+i); + u32 h0 = full_name_hash(buf+i, buf+i, j-i); + + /* Check that hashlen_string gets the length right */ + KUNIT_EXPECT_EQ_MSG(test, hashlen_len(hashlen), j-i, + "hashlen_string(%d..%d) returned length %u, expected %d", + i, j, hashlen_len(hashlen), j-i); + /* Check that the hashes match */ + KUNIT_EXPECT_EQ_MSG(test, hashlen_hash(hashlen), h0, + "hashlen_string(%d..%d) = %08x != full_name_hash() = %08x", + i, j, hashlen_hash(hashlen), h0); + + h64 = h64 << 32 | h0; /* For use with hash_64 */ + test_int_hash(test, h64, hash_or); + } /* i */ + } /* j */ + + KUNIT_EXPECT_EQ_MSG(test, hash_or[0][0], -1u, + "OR of all __hash_32 results = %#x != %#x", + hash_or[0][0], -1u); +#ifdef HAVE_ARCH__HASH_32 +#if HAVE_ARCH__HASH_32 != 1 /* Test is pointless if results match */ + KUNIT_EXPECT_EQ_MSG(test, hash_or[1][0], -1u, + "OR of all __hash_32_generic results = %#x != %#x", + hash_or[1][0], -1u); +#endif +#endif + + /* Likewise for all the i-bit hash values */ + for (i = 1; i <= 32; i++) { + u32 const m = ((u32)2 << (i-1)) - 1; /* Low i bits set */ + + KUNIT_EXPECT_EQ_MSG(test, hash_or[0][i], m, + "OR of all hash_32(%d) results = %#x (%#x expected)", + i, hash_or[0][i], m); + KUNIT_EXPECT_EQ_MSG(test, hash_or[1][i], m, + "OR of all hash_64(%d) results = %#x (%#x expected)", + i, hash_or[1][i], m); + } +} + +static struct kunit_case hash_test_cases[] __refdata = { + KUNIT_CASE(test_string_or), + KUNIT_CASE(test_hash_or), + {} +}; + +static struct kunit_suite hash_test_suite = { + .name = "hash", + .test_cases = hash_test_cases, +}; + + +kunit_test_suite(hash_test_suite); + +MODULE_LICENSE("GPL"); |