// SPDX-License-Identifier: GPL-2.0
/*
 * Test cases for memcpy(), memmove(), and memset().
 */
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <kunit/test.h>
#include <linux/device.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/overflow.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/vmalloc.h>

struct some_bytes {
        union {
                u8 data[32];
                struct {
                        u32 one;
                        u16 two;
                        u8  three;
                        /* 1 byte hole */
                        u32 four[4];
                };
        };
};

#define check(instance, v) do { \
        BUILD_BUG_ON(sizeof(instance.data) != 32);      \
        for (size_t i = 0; i < sizeof(instance.data); i++) {    \
                KUNIT_ASSERT_EQ_MSG(test, instance.data[i], v, \
                        "line %d: '%s' not initialized to 0x%02x @ %zu (saw 0x%02x)\n", \
                        __LINE__, #instance, v, i, instance.data[i]);   \
        }       \
} while (0)

#define compare(name, one, two) do { \
        BUILD_BUG_ON(sizeof(one) != sizeof(two)); \
        for (size_t i = 0; i < sizeof(one); i++) {      \
                KUNIT_EXPECT_EQ_MSG(test, one.data[i], two.data[i], \
                        "line %d: %s.data[%zu] (0x%02x) != %s.data[%zu] (0x%02x)\n", \
                        __LINE__, #one, i, one.data[i], #two, i, two.data[i]); \
        }       \
        kunit_info(test, "ok: " TEST_OP "() " name "\n");       \
} while (0)

static void memcpy_test(struct kunit *test)
{
#define TEST_OP "memcpy"
        struct some_bytes control = {
                .data = { 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20,
                          0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20,
                          0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20,
                          0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20,
                        },
        };
        struct some_bytes zero = { };
        struct some_bytes middle = {
                .data = { 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20,
                          0x20, 0x20, 0x20, 0x20, 0x00, 0x00, 0x00, 0x00,
                          0x00, 0x00, 0x00, 0x20, 0x20, 0x20, 0x20, 0x20,
                          0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20,
                        },
        };
        struct some_bytes three = {
                .data = { 0x00, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20,
                          0x20, 0x00, 0x00, 0x20, 0x20, 0x20, 0x20, 0x20,
                          0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20,
                          0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20,
                        },
        };
        struct some_bytes dest = { };
        int count;
        u8 *ptr;

        /* Verify static initializers. */
        check(control, 0x20);
        check(zero, 0);
        compare("static initializers", dest, zero);

        /* Verify assignment. */
        dest = control;
        compare("direct assignment", dest, control);

        /* Verify complete overwrite. */
        memcpy(dest.data, zero.data, sizeof(dest.data));
        compare("complete overwrite", dest, zero);

        /* Verify middle overwrite. */
        dest = control;
        memcpy(dest.data + 12, zero.data, 7);
        compare("middle overwrite", dest, middle);

        /* Verify argument side-effects aren't repeated. */
        dest = control;
        ptr = dest.data;
        count = 1;
        memcpy(ptr++, zero.data, count++);
        ptr += 8;
        memcpy(ptr++, zero.data, count++);
        compare("argument side-effects", dest, three);
#undef TEST_OP
}

static unsigned char larger_array [2048];

static void memmove_test(struct kunit *test)
{
#define TEST_OP "memmove"
        struct some_bytes control = {
                .data = { 0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99,
                          0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99,
                          0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99,
                          0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99,
                        },
        };
        struct some_bytes zero = { };
        struct some_bytes middle = {
                .data = { 0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99,
                          0x99, 0x99, 0x99, 0x99, 0x00, 0x00, 0x00, 0x00,
                          0x00, 0x00, 0x00, 0x99, 0x99, 0x99, 0x99, 0x99,
                          0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99,
                        },
        };
        struct some_bytes five = {
                .data = { 0x00, 0x00, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99,
                          0x99, 0x99, 0x00, 0x00, 0x00, 0x99, 0x99, 0x99,
                          0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99,
                          0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99,
                        },
        };
        struct some_bytes overlap = {
                .data = { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
                          0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F,
                          0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99,
                          0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99,
                        },
        };
        struct some_bytes overlap_expected = {
                .data = { 0x00, 0x01, 0x00, 0x01, 0x02, 0x03, 0x04, 0x07,
                          0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F,
                          0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99,
                          0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99, 0x99,
                        },
        };
        struct some_bytes dest = { };
        int count;
        u8 *ptr;

        /* Verify static initializers. */
        check(control, 0x99);
        check(zero, 0);
        compare("static initializers", zero, dest);

        /* Verify assignment. */
        dest = control;
        compare("direct assignment", dest, control);

        /* Verify complete overwrite. */
        memmove(dest.data, zero.data, sizeof(dest.data));
        compare("complete overwrite", dest, zero);

        /* Verify middle overwrite. */
        dest = control;
        memmove(dest.data + 12, zero.data, 7);
        compare("middle overwrite", dest, middle);

        /* Verify argument side-effects aren't repeated. */
        dest = control;
        ptr = dest.data;
        count = 2;
        memmove(ptr++, zero.data, count++);
        ptr += 9;
        memmove(ptr++, zero.data, count++);
        compare("argument side-effects", dest, five);

        /* Verify overlapping overwrite is correct. */
        ptr = &overlap.data[2];
        memmove(ptr, overlap.data, 5);
        compare("overlapping write", overlap, overlap_expected);

        /* Verify larger overlapping moves. */
        larger_array[256] = 0xAAu;
        /*
         * Test a backwards overlapping memmove first. 256 and 1024 are
         * important for i386 to use rep movsl.
         */
        memmove(larger_array, larger_array + 256, 1024);
        KUNIT_ASSERT_EQ(test, larger_array[0], 0xAAu);
        KUNIT_ASSERT_EQ(test, larger_array[256], 0x00);
        KUNIT_ASSERT_NULL(test,
                memchr(larger_array + 1, 0xaa, ARRAY_SIZE(larger_array) - 1));
        /* Test a forwards overlapping memmove. */
        larger_array[0] = 0xBBu;
        memmove(larger_array + 256, larger_array, 1024);
        KUNIT_ASSERT_EQ(test, larger_array[0], 0xBBu);
        KUNIT_ASSERT_EQ(test, larger_array[256], 0xBBu);
        KUNIT_ASSERT_NULL(test, memchr(larger_array + 1, 0xBBu, 256 - 1));
        KUNIT_ASSERT_NULL(test,
                memchr(larger_array + 257, 0xBBu, ARRAY_SIZE(larger_array) - 257));
#undef TEST_OP
}

static void memset_test(struct kunit *test)
{
#define TEST_OP "memset"
        struct some_bytes control = {
                .data = { 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30,
                          0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30,
                          0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30,
                          0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30,
                        },
        };
        struct some_bytes complete = {
                .data = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
                          0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
                          0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
                          0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
                        },
        };
        struct some_bytes middle = {
                .data = { 0x30, 0x30, 0x30, 0x30, 0x31, 0x31, 0x31, 0x31,
                          0x31, 0x31, 0x31, 0x31, 0x31, 0x31, 0x31, 0x31,
                          0x31, 0x31, 0x31, 0x31, 0x30, 0x30, 0x30, 0x30,
                          0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30,
                        },
        };
        struct some_bytes three = {
                .data = { 0x60, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30,
                          0x30, 0x61, 0x61, 0x30, 0x30, 0x30, 0x30, 0x30,
                          0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30,
                          0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30,
                        },
        };
        struct some_bytes after = {
                .data = { 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x72,
                          0x72, 0x72, 0x72, 0x72, 0x72, 0x72, 0x72, 0x72,
                          0x72, 0x72, 0x72, 0x72, 0x72, 0x72, 0x72, 0x72,
                          0x72, 0x72, 0x72, 0x72, 0x72, 0x72, 0x72, 0x72,
                        },
        };
        struct some_bytes startat = {
                .data = { 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30, 0x30,
                          0x79, 0x79, 0x79, 0x79, 0x79, 0x79, 0x79, 0x79,
                          0x79, 0x79, 0x79, 0x79, 0x79, 0x79, 0x79, 0x79,
                          0x79, 0x79, 0x79, 0x79, 0x79, 0x79, 0x79, 0x79,
                        },
        };
        struct some_bytes dest = { };
        int count, value;
        u8 *ptr;

        /* Verify static initializers. */
        check(control, 0x30);
        check(dest, 0);

        /* Verify assignment. */
        dest = control;
        compare("direct assignment", dest, control);

        /* Verify complete overwrite. */
        memset(dest.data, 0xff, sizeof(dest.data));
        compare("complete overwrite", dest, complete);

        /* Verify middle overwrite. */
        dest = control;
        memset(dest.data + 4, 0x31, 16);
        compare("middle overwrite", dest, middle);

        /* Verify argument side-effects aren't repeated. */
        dest = control;
        ptr = dest.data;
        value = 0x60;
        count = 1;
        memset(ptr++, value++, count++);
        ptr += 8;
        memset(ptr++, value++, count++);
        compare("argument side-effects", dest, three);

        /* Verify memset_after() */
        dest = control;
        memset_after(&dest, 0x72, three);
        compare("memset_after()", dest, after);

        /* Verify memset_startat() */
        dest = control;
        memset_startat(&dest, 0x79, four);
        compare("memset_startat()", dest, startat);
#undef TEST_OP
}

static u8 large_src[1024];
static u8 large_dst[2048];
static const u8 large_zero[2048];

static void set_random_nonzero(struct kunit *test, u8 *byte)
{
        int failed_rng = 0;

        while (*byte == 0) {
                get_random_bytes(byte, 1);
                KUNIT_ASSERT_LT_MSG(test, failed_rng++, 100,
                                    "Is the RNG broken?");
        }
}

static void init_large(struct kunit *test)
{
        /* Get many bit patterns. */
        get_random_bytes(large_src, ARRAY_SIZE(large_src));

        /* Make sure we have non-zero edges. */
        set_random_nonzero(test, &large_src[0]);
        set_random_nonzero(test, &large_src[ARRAY_SIZE(large_src) - 1]);

        /* Explicitly zero the entire destination. */
        memset(large_dst, 0, ARRAY_SIZE(large_dst));
}

/*
 * Instead of an indirect function call for "copy" or a giant macro,
 * use a bool to pick memcpy or memmove.
 */
static void copy_large_test(struct kunit *test, bool use_memmove)
{
        init_large(test);

        /* Copy a growing number of non-overlapping bytes ... */
        for (int bytes = 1; bytes <= ARRAY_SIZE(large_src); bytes++) {
                /* Over a shifting destination window ... */
                for (int offset = 0; offset < ARRAY_SIZE(large_src); offset++) {
                        int right_zero_pos = offset + bytes;
                        int right_zero_size = ARRAY_SIZE(large_dst) - right_zero_pos;

                        /* Copy! */
                        if (use_memmove)
                                memmove(large_dst + offset, large_src, bytes);
                        else
                                memcpy(large_dst + offset, large_src, bytes);

                        /* Did we touch anything before the copy area? */
                        KUNIT_ASSERT_EQ_MSG(test,
                                memcmp(large_dst, large_zero, offset), 0,
                                "with size %d at offset %d", bytes, offset);
                        /* Did we touch anything after the copy area? */
                        KUNIT_ASSERT_EQ_MSG(test,
                                memcmp(&large_dst[right_zero_pos], large_zero, right_zero_size), 0,
                                "with size %d at offset %d", bytes, offset);

                        /* Are we byte-for-byte exact across the copy? */
                        KUNIT_ASSERT_EQ_MSG(test,
                                memcmp(large_dst + offset, large_src, bytes), 0,
                                "with size %d at offset %d", bytes, offset);

                        /* Zero out what we copied for the next cycle. */
                        memset(large_dst + offset, 0, bytes);
                }
                /* Avoid stall warnings if this loop gets slow. */
                cond_resched();
        }
}

static void memcpy_large_test(struct kunit *test)
{
        copy_large_test(test, false);
}

static void memmove_large_test(struct kunit *test)
{
        copy_large_test(test, true);
}

/*
 * On the assumption that boundary conditions are going to be the most
 * sensitive, instead of taking a full step (inc) each iteration,
 * take single index steps for at least the first "inc"-many indexes
 * from the "start" and at least the last "inc"-many indexes before
 * the "end". When in the middle, take full "inc"-wide steps. For
 * example, calling next_step(idx, 1, 15, 3) with idx starting at 0
 * would see the following pattern: 1 2 3 4 7 10 11 12 13 14 15.
 */
static int next_step(int idx, int start, int end, int inc)
{
        start += inc;
        end -= inc;

        if (idx < start || idx + inc > end)
                inc = 1;
        return idx + inc;
}

static void inner_loop(struct kunit *test, int bytes, int d_off, int s_off)
{
        int left_zero_pos, left_zero_size;
        int right_zero_pos, right_zero_size;
        int src_pos, src_orig_pos, src_size;
        int pos;

        /* Place the source in the destination buffer. */
        memcpy(&large_dst[s_off], large_src, bytes);

        /* Copy to destination offset. */
        memmove(&large_dst[d_off], &large_dst[s_off], bytes);

        /* Make sure destination entirely matches. */
        KUNIT_ASSERT_EQ_MSG(test, memcmp(&large_dst[d_off], large_src, bytes), 0,
                "with size %d at src offset %d and dest offset %d",
                bytes, s_off, d_off);

        /* Calculate the expected zero spans. */
        if (s_off < d_off) {
                left_zero_pos = 0;
                left_zero_size = s_off;

                right_zero_pos = d_off + bytes;
                right_zero_size = ARRAY_SIZE(large_dst) - right_zero_pos;

                src_pos = s_off;
                src_orig_pos = 0;
                src_size = d_off - s_off;
        } else {
                left_zero_pos = 0;
                left_zero_size = d_off;

                right_zero_pos = s_off + bytes;
                right_zero_size = ARRAY_SIZE(large_dst) - right_zero_pos;

                src_pos = d_off + bytes;
                src_orig_pos = src_pos - s_off;
                src_size = right_zero_pos - src_pos;
        }

        /* Check non-overlapping source is unchanged.*/
        KUNIT_ASSERT_EQ_MSG(test,
                memcmp(&large_dst[src_pos], &large_src[src_orig_pos], src_size), 0,
                "with size %d at src offset %d and dest offset %d",
                bytes, s_off, d_off);

        /* Check leading buffer contents are zero. */
        KUNIT_ASSERT_EQ_MSG(test,
                memcmp(&large_dst[left_zero_pos], large_zero, left_zero_size), 0,
                "with size %d at src offset %d and dest offset %d",
                bytes, s_off, d_off);
        /* Check trailing buffer contents are zero. */
        KUNIT_ASSERT_EQ_MSG(test,
                memcmp(&large_dst[right_zero_pos], large_zero, right_zero_size), 0,
                "with size %d at src offset %d and dest offset %d",
                bytes, s_off, d_off);

        /* Zero out everything not already zeroed.*/
        pos = left_zero_pos + left_zero_size;
        memset(&large_dst[pos], 0, right_zero_pos - pos);
}

static void memmove_overlap_test(struct kunit *test)
{
        /*
         * Running all possible offset and overlap combinations takes a
         * very long time. Instead, only check up to 128 bytes offset
         * into the destination buffer (which should result in crossing
         * cachelines), with a step size of 1 through 7 to try to skip some
         * redundancy.
         */
        static const int offset_max = 128; /* less than ARRAY_SIZE(large_src); */
        static const int bytes_step = 7;
        static const int window_step = 7;

        static const int bytes_start = 1;
        static const int bytes_end = ARRAY_SIZE(large_src) + 1;

        init_large(test);

        /* Copy a growing number of overlapping bytes ... */
        for (int bytes = bytes_start; bytes < bytes_end;
             bytes = next_step(bytes, bytes_start, bytes_end, bytes_step)) {

                /* Over a shifting destination window ... */
                for (int d_off = 0; d_off < offset_max; d_off++) {
                        int s_start = max(d_off - bytes, 0);
                        int s_end = min_t(int, d_off + bytes, ARRAY_SIZE(large_src));

                        /* Over a shifting source window ... */
                        for (int s_off = s_start; s_off < s_end;
                             s_off = next_step(s_off, s_start, s_end, window_step))
                                inner_loop(test, bytes, d_off, s_off);

                        /* Avoid stall warnings. */
                        cond_resched();
                }
        }
}

static struct kunit_case memcpy_test_cases[] = {
        KUNIT_CASE(memset_test),
        KUNIT_CASE(memcpy_test),
        KUNIT_CASE_SLOW(memcpy_large_test),
        KUNIT_CASE_SLOW(memmove_test),
        KUNIT_CASE_SLOW(memmove_large_test),
        KUNIT_CASE_SLOW(memmove_overlap_test),
        {}
};

static struct kunit_suite memcpy_test_suite = {
        .name = "memcpy",
        .test_cases = memcpy_test_cases,
};

kunit_test_suite(memcpy_test_suite);

MODULE_DESCRIPTION("test cases for memcpy(), memmove(), and memset()");
MODULE_LICENSE("GPL");