// SPDX-License-Identifier: GPL-2.0
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>

typedef void(*test_ubsan_fp)(void);

#define UBSAN_TEST(config, ...) do {                                    \
                pr_info("%s " __VA_ARGS__ "%s(%s=%s)\n", __func__,      \
                        sizeof(" " __VA_ARGS__) > 2 ? " " : "",         \
                        #config, IS_ENABLED(config) ? "y" : "n");       \
        } while (0)

static void test_ubsan_add_overflow(void)
{
        volatile int val = INT_MAX;

        UBSAN_TEST(CONFIG_UBSAN_INTEGER_WRAP);
        val += 2;
}

static void test_ubsan_sub_overflow(void)
{
        volatile int val = INT_MIN;
        volatile int val2 = 2;

        UBSAN_TEST(CONFIG_UBSAN_INTEGER_WRAP);
        val -= val2;
}

static void test_ubsan_mul_overflow(void)
{
        volatile int val = INT_MAX / 2;

        UBSAN_TEST(CONFIG_UBSAN_INTEGER_WRAP);
        val *= 3;
}

static void test_ubsan_negate_overflow(void)
{
        volatile int val = INT_MIN;

        UBSAN_TEST(CONFIG_UBSAN_INTEGER_WRAP);
        val = -val;
}

static void test_ubsan_divrem_overflow(void)
{
        volatile int val = 16;
        volatile int val2 = 0;

        UBSAN_TEST(CONFIG_UBSAN_DIV_ZERO);
        val /= val2;
}

static void test_ubsan_truncate_signed(void)
{
        volatile long val = LONG_MAX;
        volatile int val2 = 0;

        UBSAN_TEST(CONFIG_UBSAN_INTEGER_WRAP);
        val2 = val;
}

static void test_ubsan_shift_out_of_bounds(void)
{
        volatile int neg = -1, wrap = 4;
        volatile int val1 = 10;
        volatile int val2 = INT_MAX;

        UBSAN_TEST(CONFIG_UBSAN_SHIFT, "negative exponent");
        val1 <<= neg;

        UBSAN_TEST(CONFIG_UBSAN_SHIFT, "left overflow");
        val2 <<= wrap;
}

static void test_ubsan_out_of_bounds(void)
{
        int i = 4, j = 4, k = -1;
        volatile struct {
                char above[4]; /* Protect surrounding memory. */
                int arr[4];
                char below[4]; /* Protect surrounding memory. */
        } data;

        OPTIMIZER_HIDE_VAR(i);
        OPTIMIZER_HIDE_VAR(j);
        OPTIMIZER_HIDE_VAR(k);

        UBSAN_TEST(CONFIG_UBSAN_BOUNDS, "above");
        data.arr[j] = i;

        UBSAN_TEST(CONFIG_UBSAN_BOUNDS, "below");
        data.arr[k] = i;
}

enum ubsan_test_enum {
        UBSAN_TEST_ZERO = 0,
        UBSAN_TEST_ONE,
        UBSAN_TEST_MAX,
};

static void test_ubsan_load_invalid_value(void)
{
        volatile char *dst, *src;
        bool val, val2, *ptr;
        enum ubsan_test_enum eval, eval2, *eptr;
        unsigned char c = 0xff;

        UBSAN_TEST(CONFIG_UBSAN_BOOL, "bool");
        dst = (char *)&val;
        src = &c;
        *dst = *src;

        ptr = &val2;
        val2 = val;

        UBSAN_TEST(CONFIG_UBSAN_ENUM, "enum");
        dst = (char *)&eval;
        src = &c;
        *dst = *src;

        eptr = &eval2;
        eval2 = eval;
}

static void test_ubsan_misaligned_access(void)
{
        volatile char arr[5] __aligned(4) = {1, 2, 3, 4, 5};
        volatile int *ptr, val = 6;

        UBSAN_TEST(CONFIG_UBSAN_ALIGNMENT);
        ptr = (int *)(arr + 1);
        *ptr = val;
}

static const test_ubsan_fp test_ubsan_array[] = {
        test_ubsan_add_overflow,
        test_ubsan_sub_overflow,
        test_ubsan_mul_overflow,
        test_ubsan_negate_overflow,
        test_ubsan_truncate_signed,
        test_ubsan_shift_out_of_bounds,
        test_ubsan_out_of_bounds,
        test_ubsan_load_invalid_value,
        test_ubsan_misaligned_access,
};

/* Excluded because they Oops the module. */
static __used const test_ubsan_fp skip_ubsan_array[] = {
        test_ubsan_divrem_overflow,
};

static int __init test_ubsan_init(void)
{
        unsigned int i;

        for (i = 0; i < ARRAY_SIZE(test_ubsan_array); i++)
                test_ubsan_array[i]();

        return 0;
}
module_init(test_ubsan_init);

static void __exit test_ubsan_exit(void)
{
        /* do nothing */
}
module_exit(test_ubsan_exit);

MODULE_AUTHOR("Jinbum Park <jinb.park7@gmail.com>");
MODULE_DESCRIPTION("UBSAN unit test");
MODULE_LICENSE("GPL v2");