/* * 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(). */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt "\n" #include <linux/compiler.h>#include <linux/types.h>#include <linux/module.h>#include <linux/hash.h>#include <linux/stringhash.h>#include <linux/printk.h> /* 32-bit XORSHIFT generator.  Seed must not be zero. */static u32 __init __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 __init __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 __initfill_buf(char *buf, size_t len, u32 seed){	size_t i; 	for (i = 0; i < len; i++) {		seed = xorshift(seed);		buf[i] = mod255(seed);	}} /* * 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 bool __inittest_int_hash(unsigned long long h64, u32 hash_or[2][33]){	int k;	u32 h0 = (u32)h64, h1, h2; 	/* Test __hash32 */	hash_or[0][0] |= h1 = __hash_32(h0);#ifdef HAVE_ARCH__HASH_32	hash_or[1][0] |= h2 = __hash_32_generic(h0);#if HAVE_ARCH__HASH_32 == 1	if (h1 != h2) {		pr_err("__hash_32(%#x) = %#x != __hash_32_generic() = %#x",			h0, h1, h2);		return false;	}#endif#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] |= h1 = hash_32(h0, k);		if (h1 > m) {			pr_err("hash_32(%#x, %d) = %#x > %#x", h0, k, h1, m);			return false;		}#ifdef HAVE_ARCH_HASH_32		h2 = hash_32_generic(h0, k);#if HAVE_ARCH_HASH_32 == 1		if (h1 != h2) {			pr_err("hash_32(%#x, %d) = %#x != hash_32_generic() "				" = %#x", h0, k, h1, h2);			return false;		}#else		if (h2 > m) {			pr_err("hash_32_generic(%#x, %d) = %#x > %#x",				h0, k, h1, m);			return false;		}#endif#endif		/* Test hash_64 */		hash_or[1][k] |= h1 = hash_64(h64, k);		if (h1 > m) {			pr_err("hash_64(%#llx, %d) = %#x > %#x", h64, k, h1, m);			return false;		}#ifdef HAVE_ARCH_HASH_64		h2 = hash_64_generic(h64, k);#if HAVE_ARCH_HASH_64 == 1		if (h1 != h2) {			pr_err("hash_64(%#llx, %d) = %#x != hash_64_generic() "				"= %#x", h64, k, h1, h2);			return false;		}#else		if (h2 > m) {			pr_err("hash_64_generic(%#llx, %d) = %#x > %#x",				h64, k, h1, m);			return false;		}#endif#endif	} 	(void)h2;	/* Suppress unused variable warning */	return true;} #define SIZE 256	/* Run time is cubic in SIZE */ static int __inittest_hash_init(void){	char buf[SIZE+1];	u32 string_or = 0, hash_or[2][33] = { { 0, } };	unsigned tests = 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 */			if (hashlen_len(hashlen) != j-i) {				pr_err("hashlen_string(%d..%d) returned length"					" %u, expected %d",					i, j, hashlen_len(hashlen), j-i);				return -EINVAL;			}			/* Check that the hashes match */			if (hashlen_hash(hashlen) != h0) {				pr_err("hashlen_string(%d..%d) = %08x != "					"full_name_hash() = %08x",					i, j, hashlen_hash(hashlen), h0);				return -EINVAL;			} 			string_or |= h0;			h64 = h64 << 32 | h0;	/* For use with hash_64 */			if (!test_int_hash(h64, hash_or))				return -EINVAL;			tests++;		} /* i */	} /* j */ 	/* The OR of all the hash values should cover all the bits */	if (~string_or) {		pr_err("OR of all string hash results = %#x != %#x",			string_or, -1u);		return -EINVAL;	}	if (~hash_or[0][0]) {		pr_err("OR of all __hash_32 results = %#x != %#x",			hash_or[0][0], -1u);		return -EINVAL;	}#ifdef HAVE_ARCH__HASH_32#if HAVE_ARCH__HASH_32 != 1	/* Test is pointless if results match */	if (~hash_or[1][0]) {		pr_err("OR of all __hash_32_generic results = %#x != %#x",			hash_or[1][0], -1u);		return -EINVAL;	}#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 */ 		if (hash_or[0][i] != m) {			pr_err("OR of all hash_32(%d) results = %#x "				"(%#x expected)", i, hash_or[0][i], m);			return -EINVAL;		}		if (hash_or[1][i] != m) {			pr_err("OR of all hash_64(%d) results = %#x "				"(%#x expected)", i, hash_or[1][i], m);			return -EINVAL;		}	} 	/* Issue notices about skipped tests. */#ifdef HAVE_ARCH__HASH_32#if HAVE_ARCH__HASH_32 != 1	pr_info("__hash_32() is arch-specific; not compared to generic.");#endif#else	pr_info("__hash_32() has no arch implementation to test.");#endif#ifdef HAVE_ARCH_HASH_32#if HAVE_ARCH_HASH_32 != 1	pr_info("hash_32() is arch-specific; not compared to generic.");#endif#else	pr_info("hash_32() has no arch implementation to test.");#endif#ifdef HAVE_ARCH_HASH_64#if HAVE_ARCH_HASH_64 != 1	pr_info("hash_64() is arch-specific; not compared to generic.");#endif#else	pr_info("hash_64() has no arch implementation to test.");#endif 	pr_notice("%u tests passed.", tests); 	return 0;} static void __exit test_hash_exit(void){} module_init(test_hash_init);	/* Does everything */module_exit(test_hash_exit);	/* Does nothing */ MODULE_LICENSE("GPL");