// 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_32static voidtest_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_64static voidtest_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 voidtest_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, &params);#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, &params, &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_DESCRIPTION("Test cases for <linux/hash.h> and <linux/stringhash.h>");MODULE_LICENSE("GPL");