// 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
  ",	\
  				__func__, failures, num_tests);		\
  		else		\
  			pr_info("all %d tests in %s passed
  ",		\
  				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;
  }

  static int __init do_kmem_cache_size_bulk(int size, int *total_failures)
  {
  	struct kmem_cache *c;
  	int i, iter, maxiter = 1024;
  	int num, bytes;
  	bool fail = false;
  	void *objects[10];
  
  	c = kmem_cache_create("test_cache", size, size, 0, NULL);
  	for (iter = 0; (iter < maxiter) && !fail; iter++) {
  		num = kmem_cache_alloc_bulk(c, GFP_KERNEL, ARRAY_SIZE(objects),
  					    objects);
  		for (i = 0; i < num; i++) {
  			bytes = count_nonzero_bytes(objects[i], size);
  			if (bytes)
  				fail = true;
  			fill_with_garbage(objects[i], size);
  		}
  
  		if (num)
  			kmem_cache_free_bulk(c, num, objects);
  	}
  	*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);
  		}

  		num_tests += do_kmem_cache_size_bulk(size, &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!
  ", num_tests);
  	else
  		pr_info("failures: %d out of %d
  ", failures, num_tests);
  
  	return failures ? -EINVAL : 0;
  }
  module_init(test_meminit_init);
  
  MODULE_LICENSE("GPL");