// 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_DESCRIPTION("Test cases for <linux/hash.h> and <linux/stringhash.h>");
MODULE_LICENSE("GPL");
Codebase Browser
linux