// SPDX-License-Identifier: GPL-2.0
/*
 * Test cases for SL[AOU]B/page initialization at alloc/free time.
 */
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/vmalloc.h>

#define GARBAGE_INT (0x09A7BA9E)
#define GARBAGE_BYTE (0x9E)

#define REPORT_FAILURES_IN_FN() \
        do {    \
                if (failures)   \
                        pr_info("%s failed %d out of %d times\n",       \
                                __func__, failures, num_tests);         \
                else            \
                        pr_info("all %d tests in %s passed\n",          \
                                num_tests, __func__);                   \
        } while (0)

/* Calculate the number of uninitialized bytes in the buffer. */
static int __init count_nonzero_bytes(void *ptr, size_t size)
{
        int i, ret = 0;
        unsigned char *p = (unsigned char *)ptr;

        for (i = 0; i < size; i++)
                if (p[i])
                        ret++;
        return ret;
}

/* Fill a buffer with garbage, skipping |skip| first bytes. */
static void __init fill_with_garbage_skip(void *ptr, int size, size_t skip)
{
        unsigned int *p = (unsigned int *)((char *)ptr + skip);
        int i = 0;

        WARN_ON(skip > size);
        size -= skip;

        while (size >= sizeof(*p)) {
                p[i] = GARBAGE_INT;
                i++;
                size -= sizeof(*p);
        }
        if (size)
                memset(&p[i], GARBAGE_BYTE, size);
}

static void __init fill_with_garbage(void *ptr, size_t size)
{
        fill_with_garbage_skip(ptr, size, 0);
}

static int __init do_alloc_pages_order(int order, int *total_failures)
{
        struct page *page;
        void *buf;
        size_t size = PAGE_SIZE << order;

        page = alloc_pages(GFP_KERNEL, order);
        buf = page_address(page);
        fill_with_garbage(buf, size);
        __free_pages(page, order);

        page = alloc_pages(GFP_KERNEL, order);
        buf = page_address(page);
        if (count_nonzero_bytes(buf, size))
                (*total_failures)++;
        fill_with_garbage(buf, size);
        __free_pages(page, order);
        return 1;
}

/* Test the page allocator by calling alloc_pages with different orders. */
static int __init test_pages(int *total_failures)
{
        int failures = 0, num_tests = 0;
        int i;

        for (i = 0; i < 10; i++)
                num_tests += do_alloc_pages_order(i, &failures);

        REPORT_FAILURES_IN_FN();
        *total_failures += failures;
        return num_tests;
}

/* Test kmalloc() with given parameters. */
static int __init do_kmalloc_size(size_t size, int *total_failures)
{
        void *buf;

        buf = kmalloc(size, GFP_KERNEL);
        fill_with_garbage(buf, size);
        kfree(buf);

        buf = kmalloc(size, GFP_KERNEL);
        if (count_nonzero_bytes(buf, size))
                (*total_failures)++;
        fill_with_garbage(buf, size);
        kfree(buf);
        return 1;
}

/* Test vmalloc() with given parameters. */
static int __init do_vmalloc_size(size_t size, int *total_failures)
{
        void *buf;

        buf = vmalloc(size);
        fill_with_garbage(buf, size);
        vfree(buf);

        buf = vmalloc(size);
        if (count_nonzero_bytes(buf, size))
                (*total_failures)++;
        fill_with_garbage(buf, size);
        vfree(buf);
        return 1;
}

/* Test kmalloc()/vmalloc() by allocating objects of different sizes. */
static int __init test_kvmalloc(int *total_failures)
{
        int failures = 0, num_tests = 0;
        int i, size;

        for (i = 0; i < 20; i++) {
                size = 1 << i;
                num_tests += do_kmalloc_size(size, &failures);
                num_tests += do_vmalloc_size(size, &failures);
        }

        REPORT_FAILURES_IN_FN();
        *total_failures += failures;
        return num_tests;
}

#define CTOR_BYTES (sizeof(unsigned int))
#define CTOR_PATTERN (0x41414141)
/* Initialize the first 4 bytes of the object. */
static void test_ctor(void *obj)
{
        *(unsigned int *)obj = CTOR_PATTERN;
}

/*
 * Check the invariants for the buffer allocated from a slab cache.
 * If the cache has a test constructor, the first 4 bytes of the object must
 * always remain equal to CTOR_PATTERN.
 * If the cache isn't an RCU-typesafe one, or if the allocation is done with
 * __GFP_ZERO, then the object contents must be zeroed after allocation.
 * If the cache is an RCU-typesafe one, the object contents must never be
 * zeroed after the first use. This is checked by memcmp() in
 * do_kmem_cache_size().
 */
static bool __init check_buf(void *buf, int size, bool want_ctor,
                             bool want_rcu, bool want_zero)
{
        int bytes;
        bool fail = false;

        bytes = count_nonzero_bytes(buf, size);
        WARN_ON(want_ctor && want_zero);
        if (want_zero)
                return bytes;
        if (want_ctor) {
                if (*(unsigned int *)buf != CTOR_PATTERN)
                        fail = 1;
        } else {
                if (bytes)
                        fail = !want_rcu;
        }
        return fail;
}

/*
 * Test kmem_cache with given parameters:
 *  want_ctor - use a constructor;
 *  want_rcu - use SLAB_TYPESAFE_BY_RCU;
 *  want_zero - use __GFP_ZERO.
 */
static int __init do_kmem_cache_size(size_t size, bool want_ctor,
                                     bool want_rcu, bool want_zero,
                                     int *total_failures)
{
        struct kmem_cache *c;
        int iter;
        bool fail = false;
        gfp_t alloc_mask = GFP_KERNEL | (want_zero ? __GFP_ZERO : 0);
        void *buf, *buf_copy;

        c = kmem_cache_create("test_cache", size, 1,
                              want_rcu ? SLAB_TYPESAFE_BY_RCU : 0,
                              want_ctor ? test_ctor : NULL);
        for (iter = 0; iter < 10; iter++) {
                buf = kmem_cache_alloc(c, alloc_mask);
                /* Check that buf is zeroed, if it must be. */
                fail = check_buf(buf, size, want_ctor, want_rcu, want_zero);
                fill_with_garbage_skip(buf, size, want_ctor ? CTOR_BYTES : 0);

                if (!want_rcu) {
                        kmem_cache_free(c, buf);
                        continue;
                }

                /*
                 * If this is an RCU cache, use a critical section to ensure we
                 * can touch objects after they're freed.
                 */
                rcu_read_lock();
                /*
                 * Copy the buffer to check that it's not wiped on
                 * free().
                 */
                buf_copy = kmalloc(size, GFP_ATOMIC);
                if (buf_copy)
                        memcpy(buf_copy, buf, size);

                kmem_cache_free(c, buf);
                /*
                 * Check that |buf| is intact after kmem_cache_free().
                 * |want_zero| is false, because we wrote garbage to
                 * the buffer already.
                 */
                fail |= check_buf(buf, size, want_ctor, want_rcu,
                                  false);
                if (buf_copy) {
                        fail |= (bool)memcmp(buf, buf_copy, size);
                        kfree(buf_copy);
                }
                rcu_read_unlock();
        }
        kmem_cache_destroy(c);

        *total_failures += fail;
        return 1;
}

/*
 * Check that the data written to an RCU-allocated object survives
 * reallocation.
 */
static int __init do_kmem_cache_rcu_persistent(int size, int *total_failures)
{
        struct kmem_cache *c;
        void *buf, *buf_contents, *saved_ptr;
        void **used_objects;
        int i, iter, maxiter = 1024;
        bool fail = false;

        c = kmem_cache_create("test_cache", size, size, SLAB_TYPESAFE_BY_RCU,
                              NULL);
        buf = kmem_cache_alloc(c, GFP_KERNEL);
        saved_ptr = buf;
        fill_with_garbage(buf, size);
        buf_contents = kmalloc(size, GFP_KERNEL);
        if (!buf_contents)
                goto out;
        used_objects = kmalloc_array(maxiter, sizeof(void *), GFP_KERNEL);
        if (!used_objects) {
                kfree(buf_contents);
                goto out;
        }
        memcpy(buf_contents, buf, size);
        kmem_cache_free(c, buf);
        /*
         * Run for a fixed number of iterations. If we never hit saved_ptr,
         * assume the test passes.
         */
        for (iter = 0; iter < maxiter; iter++) {
                buf = kmem_cache_alloc(c, GFP_KERNEL);
                used_objects[iter] = buf;
                if (buf == saved_ptr) {
                        fail = memcmp(buf_contents, buf, size);
                        for (i = 0; i <= iter; i++)
                                kmem_cache_free(c, used_objects[i]);
                        goto free_out;
                }
        }

free_out:
        kmem_cache_destroy(c);
        kfree(buf_contents);
        kfree(used_objects);
out:
        *total_failures += fail;
        return 1;
}

/*
 * Test kmem_cache allocation by creating caches of different sizes, with and
 * without constructors, with and without SLAB_TYPESAFE_BY_RCU.
 */
static int __init test_kmemcache(int *total_failures)
{
        int failures = 0, num_tests = 0;
        int i, flags, size;
        bool ctor, rcu, zero;

        for (i = 0; i < 10; i++) {
                size = 8 << i;
                for (flags = 0; flags < 8; flags++) {
                        ctor = flags & 1;
                        rcu = flags & 2;
                        zero = flags & 4;
                        if (ctor & zero)
                                continue;
                        num_tests += do_kmem_cache_size(size, ctor, rcu, zero,
                                                        &failures);
                }
        }
        REPORT_FAILURES_IN_FN();
        *total_failures += failures;
        return num_tests;
}

/* Test the behavior of SLAB_TYPESAFE_BY_RCU caches of different sizes. */
static int __init test_rcu_persistent(int *total_failures)
{
        int failures = 0, num_tests = 0;
        int i, size;

        for (i = 0; i < 10; i++) {
                size = 8 << i;
                num_tests += do_kmem_cache_rcu_persistent(size, &failures);
        }
        REPORT_FAILURES_IN_FN();
        *total_failures += failures;
        return num_tests;
}

/*
 * Run the tests. Each test function returns the number of executed tests and
 * updates |failures| with the number of failed tests.
 */
static int __init test_meminit_init(void)
{
        int failures = 0, num_tests = 0;

        num_tests += test_pages(&failures);
        num_tests += test_kvmalloc(&failures);
        num_tests += test_kmemcache(&failures);
        num_tests += test_rcu_persistent(&failures);

        if (failures == 0)
                pr_info("all %d tests passed!\n", num_tests);
        else
                pr_info("failures: %d out of %d\n", failures, num_tests);

        return failures ? -EINVAL : 0;
}
module_init(test_meminit_init);

MODULE_LICENSE("GPL");