lib/test_meminit.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Test cases for SL[AOU]B/page initialization at alloc/free time.
   4  */
   5 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
   6
   7 #include <linux/init.h>
   8 #include <linux/kernel.h>
   9 #include <linux/mm.h>
  10 #include <linux/module.h>
  11 #include <linux/slab.h>
  12 #include <linux/string.h>
  13 #include <linux/vmalloc.h>
  14
  15 #define GARBAGE_INT (0x09A7BA9E)
  16 #define GARBAGE_BYTE (0x9E)
  17
  18 #define REPORT_FAILURES_IN_FN() \
  19         do {    \
  20                 if (failures)   \
  21                         pr_info("%s failed %d out of %d times\n",       \
  22                                 __func__, failures, num_tests);         \
  23                 else            \
  24                         pr_info("all %d tests in %s passed\n",          \
  25                                 num_tests, __func__);                   \
  26         } while (0)
  27
  28 /* Calculate the number of uninitialized bytes in the buffer. */
  29 static int __init count_nonzero_bytes(void *ptr, size_t size)
  30 {
  31         int i, ret = 0;
  32         unsigned char *p = (unsigned char *)ptr;
  33
  34         for (i = 0; i < size; i++)
  35                 if (p[i])
  36                         ret++;
  37         return ret;
  38 }
  39
  40 /* Fill a buffer with garbage, skipping |skip| first bytes. */
  41 static void __init fill_with_garbage_skip(void *ptr, int size, size_t skip)
  42 {
  43         unsigned int *p = (unsigned int *)((char *)ptr + skip);
  44         int i = 0;
  45
  46         WARN_ON(skip > size);
  47         size -= skip;
  48
  49         while (size >= sizeof(*p)) {
  50                 p[i] = GARBAGE_INT;
  51                 i++;
  52                 size -= sizeof(*p);
  53         }
  54         if (size)
  55                 memset(&p[i], GARBAGE_BYTE, size);
  56 }
  57
  58 static void __init fill_with_garbage(void *ptr, size_t size)
  59 {
  60         fill_with_garbage_skip(ptr, size, 0);
  61 }
  62
  63 static int __init do_alloc_pages_order(int order, int *total_failures)
  64 {
  65         struct page *page;
  66         void *buf;
  67         size_t size = PAGE_SIZE << order;
  68
  69         page = alloc_pages(GFP_KERNEL, order);
  70         if (!page)
  71                 goto err;
  72         buf = page_address(page);
  73         fill_with_garbage(buf, size);
  74         __free_pages(page, order);
  75
  76         page = alloc_pages(GFP_KERNEL, order);
  77         if (!page)
  78                 goto err;
  79         buf = page_address(page);
  80         if (count_nonzero_bytes(buf, size))
  81                 (*total_failures)++;
  82         fill_with_garbage(buf, size);
  83         __free_pages(page, order);
  84         return 1;
  85 err:
  86         (*total_failures)++;
  87         return 1;
  88 }
  89
  90 /* Test the page allocator by calling alloc_pages with different orders. */
  91 static int __init test_pages(int *total_failures)
  92 {
  93         int failures = 0, num_tests = 0;
  94         int i;
  95
  96         for (i = 0; i < NR_PAGE_ORDERS; i++)
  97                 num_tests += do_alloc_pages_order(i, &failures);
  98
  99         REPORT_FAILURES_IN_FN();
 100         *total_failures += failures;
 101         return num_tests;
 102 }
 103
 104 /* Test kmalloc() with given parameters. */
 105 static int __init do_kmalloc_size(size_t size, int *total_failures)
 106 {
 107         void *buf;
 108
 109         buf = kmalloc(size, GFP_KERNEL);
 110         if (!buf)
 111                 goto err;
 112         fill_with_garbage(buf, size);
 113         kfree(buf);
 114
 115         buf = kmalloc(size, GFP_KERNEL);
 116         if (!buf)
 117                 goto err;
 118         if (count_nonzero_bytes(buf, size))
 119                 (*total_failures)++;
 120         fill_with_garbage(buf, size);
 121         kfree(buf);
 122         return 1;
 123 err:
 124         (*total_failures)++;
 125         return 1;
 126 }
 127
 128 /* Test vmalloc() with given parameters. */
 129 static int __init do_vmalloc_size(size_t size, int *total_failures)
 130 {
 131         void *buf;
 132
 133         buf = vmalloc(size);
 134         if (!buf)
 135                 goto err;
 136         fill_with_garbage(buf, size);
 137         vfree(buf);
 138
 139         buf = vmalloc(size);
 140         if (!buf)
 141                 goto err;
 142         if (count_nonzero_bytes(buf, size))
 143                 (*total_failures)++;
 144         fill_with_garbage(buf, size);
 145         vfree(buf);
 146         return 1;
 147 err:
 148         (*total_failures)++;
 149         return 1;
 150 }
 151
 152 /* Test kmalloc()/vmalloc() by allocating objects of different sizes. */
 153 static int __init test_kvmalloc(int *total_failures)
 154 {
 155         int failures = 0, num_tests = 0;
 156         int i, size;
 157
 158         for (i = 0; i < 20; i++) {
 159                 size = 1 << i;
 160                 num_tests += do_kmalloc_size(size, &failures);
 161                 num_tests += do_vmalloc_size(size, &failures);
 162         }
 163
 164         REPORT_FAILURES_IN_FN();
 165         *total_failures += failures;
 166         return num_tests;
 167 }
 168
 169 #define CTOR_BYTES (sizeof(unsigned int))
 170 #define CTOR_PATTERN (0x41414141)
 171 /* Initialize the first 4 bytes of the object. */
 172 static void test_ctor(void *obj)
 173 {
 174         *(unsigned int *)obj = CTOR_PATTERN;
 175 }
 176
 177 /*
 178  * Check the invariants for the buffer allocated from a slab cache.
 179  * If the cache has a test constructor, the first 4 bytes of the object must
 180  * always remain equal to CTOR_PATTERN.
 181  * If the cache isn't an RCU-typesafe one, or if the allocation is done with
 182  * __GFP_ZERO, then the object contents must be zeroed after allocation.
 183  * If the cache is an RCU-typesafe one, the object contents must never be
 184  * zeroed after the first use. This is checked by memcmp() in
 185  * do_kmem_cache_size().
 186  */
 187 static bool __init check_buf(void *buf, int size, bool want_ctor,
 188                              bool want_rcu, bool want_zero)
 189 {
 190         int bytes;
 191         bool fail = false;
 192
 193         bytes = count_nonzero_bytes(buf, size);
 194         WARN_ON(want_ctor && want_zero);
 195         if (want_zero)
 196                 return bytes;
 197         if (want_ctor) {
 198                 if (*(unsigned int *)buf != CTOR_PATTERN)
 199                         fail = 1;
 200         } else {
 201                 if (bytes)
 202                         fail = !want_rcu;
 203         }
 204         return fail;
 205 }
 206
 207 #define BULK_SIZE 100
 208 static void *bulk_array[BULK_SIZE];
 209
 210 /*
 211  * Test kmem_cache with given parameters:
 212  *  want_ctor - use a constructor;
 213  *  want_rcu - use SLAB_TYPESAFE_BY_RCU;
 214  *  want_zero - use __GFP_ZERO.
 215  */
 216 static int __init do_kmem_cache_size(size_t size, bool want_ctor,
 217                                      bool want_rcu, bool want_zero,
 218                                      int *total_failures)
 219 {
 220         struct kmem_cache *c;
 221         int iter;
 222         bool fail = false;
 223         gfp_t alloc_mask = GFP_KERNEL | (want_zero ? __GFP_ZERO : 0);
 224         void *buf, *buf_copy;
 225
 226         c = kmem_cache_create("test_cache", size, 1,
 227                               want_rcu ? SLAB_TYPESAFE_BY_RCU : 0,
 228                               want_ctor ? test_ctor : NULL);
 229         for (iter = 0; iter < 10; iter++) {
 230                 /* Do a test of bulk allocations */
 231                 if (!want_rcu && !want_ctor) {
 232                         int ret;
 233
 234                         ret = kmem_cache_alloc_bulk(c, alloc_mask, BULK_SIZE, bulk_array);
 235                         if (!ret) {
 236                                 fail = true;
 237                         } else {
 238                                 int i;
 239                                 for (i = 0; i < ret; i++)
 240                                         fail |= check_buf(bulk_array[i], size, want_ctor, want_rcu, want_zero);
 241                                 kmem_cache_free_bulk(c, ret, bulk_array);
 242                         }
 243                 }
 244
 245                 buf = kmem_cache_alloc(c, alloc_mask);
 246                 /* Check that buf is zeroed, if it must be. */
 247                 fail |= check_buf(buf, size, want_ctor, want_rcu, want_zero);
 248                 fill_with_garbage_skip(buf, size, want_ctor ? CTOR_BYTES : 0);
 249
 250                 if (!want_rcu) {
 251                         kmem_cache_free(c, buf);
 252                         continue;
 253                 }
 254
 255                 /*
 256                  * If this is an RCU cache, use a critical section to ensure we
 257                  * can touch objects after they're freed.
 258                  */
 259                 rcu_read_lock();
 260                 /*
 261                  * Copy the buffer to check that it's not wiped on
 262                  * free().
 263                  */
 264                 buf_copy = kmalloc(size, GFP_ATOMIC);
 265                 if (buf_copy)
 266                         memcpy(buf_copy, buf, size);
 267
 268                 kmem_cache_free(c, buf);
 269                 /*
 270                  * Check that |buf| is intact after kmem_cache_free().
 271                  * |want_zero| is false, because we wrote garbage to
 272                  * the buffer already.
 273                  */
 274                 fail |= check_buf(buf, size, want_ctor, want_rcu,
 275                                   false);
 276                 if (buf_copy) {
 277                         fail |= (bool)memcmp(buf, buf_copy, size);
 278                         kfree(buf_copy);
 279                 }
 280                 rcu_read_unlock();
 281         }
 282         kmem_cache_destroy(c);
 283
 284         *total_failures += fail;
 285         return 1;
 286 }
 287
 288 /*
 289  * Check that the data written to an RCU-allocated object survives
 290  * reallocation.
 291  */
 292 static int __init do_kmem_cache_rcu_persistent(int size, int *total_failures)
 293 {
 294         struct kmem_cache *c;
 295         void *buf, *buf_contents, *saved_ptr;
 296         void **used_objects;
 297         int i, iter, maxiter = 1024;
 298         bool fail = false;
 299
 300         c = kmem_cache_create("test_cache", size, size, SLAB_TYPESAFE_BY_RCU,
 301                               NULL);
 302         buf = kmem_cache_alloc(c, GFP_KERNEL);
 303         if (!buf)
 304                 goto out;
 305         saved_ptr = buf;
 306         fill_with_garbage(buf, size);
 307         buf_contents = kmalloc(size, GFP_KERNEL);
 308         if (!buf_contents) {
 309                 kmem_cache_free(c, buf);
 310                 goto out;
 311         }
 312         used_objects = kmalloc_array(maxiter, sizeof(void *), GFP_KERNEL);
 313         if (!used_objects) {
 314                 kmem_cache_free(c, buf);
 315                 kfree(buf_contents);
 316                 goto out;
 317         }
 318         memcpy(buf_contents, buf, size);
 319         kmem_cache_free(c, buf);
 320         /*
 321          * Run for a fixed number of iterations. If we never hit saved_ptr,
 322          * assume the test passes.
 323          */
 324         for (iter = 0; iter < maxiter; iter++) {
 325                 buf = kmem_cache_alloc(c, GFP_KERNEL);
 326                 used_objects[iter] = buf;
 327                 if (buf == saved_ptr) {
 328                         fail = memcmp(buf_contents, buf, size);
 329                         for (i = 0; i <= iter; i++)
 330                                 kmem_cache_free(c, used_objects[i]);
 331                         goto free_out;
 332                 }
 333         }
 334
 335         for (iter = 0; iter < maxiter; iter++)
 336                 kmem_cache_free(c, used_objects[iter]);
 337
 338 free_out:
 339         kfree(buf_contents);
 340         kfree(used_objects);
 341 out:
 342         kmem_cache_destroy(c);
 343         *total_failures += fail;
 344         return 1;
 345 }
 346
 347 static int __init do_kmem_cache_size_bulk(int size, int *total_failures)
 348 {
 349         struct kmem_cache *c;
 350         int i, iter, maxiter = 1024;
 351         int num, bytes;
 352         bool fail = false;
 353         void *objects[10];
 354
 355         c = kmem_cache_create("test_cache", size, size, 0, NULL);
 356         for (iter = 0; (iter < maxiter) && !fail; iter++) {
 357                 num = kmem_cache_alloc_bulk(c, GFP_KERNEL, ARRAY_SIZE(objects),
 358                                             objects);
 359                 for (i = 0; i < num; i++) {
 360                         bytes = count_nonzero_bytes(objects[i], size);
 361                         if (bytes)
 362                                 fail = true;
 363                         fill_with_garbage(objects[i], size);
 364                 }
 365
 366                 if (num)
 367                         kmem_cache_free_bulk(c, num, objects);
 368         }
 369         kmem_cache_destroy(c);
 370         *total_failures += fail;
 371         return 1;
 372 }
 373
 374 /*
 375  * Test kmem_cache allocation by creating caches of different sizes, with and
 376  * without constructors, with and without SLAB_TYPESAFE_BY_RCU.
 377  */
 378 static int __init test_kmemcache(int *total_failures)
 379 {
 380         int failures = 0, num_tests = 0;
 381         int i, flags, size;
 382         bool ctor, rcu, zero;
 383
 384         for (i = 0; i < 10; i++) {
 385                 size = 8 << i;
 386                 for (flags = 0; flags < 8; flags++) {
 387                         ctor = flags & 1;
 388                         rcu = flags & 2;
 389                         zero = flags & 4;
 390                         if (ctor & zero)
 391                                 continue;
 392                         num_tests += do_kmem_cache_size(size, ctor, rcu, zero,
 393                                                         &failures);
 394                 }
 395                 num_tests += do_kmem_cache_size_bulk(size, &failures);
 396         }
 397         REPORT_FAILURES_IN_FN();
 398         *total_failures += failures;
 399         return num_tests;
 400 }
 401
 402 /* Test the behavior of SLAB_TYPESAFE_BY_RCU caches of different sizes. */
 403 static int __init test_rcu_persistent(int *total_failures)
 404 {
 405         int failures = 0, num_tests = 0;
 406         int i, size;
 407
 408         for (i = 0; i < 10; i++) {
 409                 size = 8 << i;
 410                 num_tests += do_kmem_cache_rcu_persistent(size, &failures);
 411         }
 412         REPORT_FAILURES_IN_FN();
 413         *total_failures += failures;
 414         return num_tests;
 415 }
 416
 417 /*
 418  * Run the tests. Each test function returns the number of executed tests and
 419  * updates |failures| with the number of failed tests.
 420  */
 421 static int __init test_meminit_init(void)
 422 {
 423         int failures = 0, num_tests = 0;
 424
 425         num_tests += test_pages(&failures);
 426         num_tests += test_kvmalloc(&failures);
 427         num_tests += test_kmemcache(&failures);
 428         num_tests += test_rcu_persistent(&failures);
 429
 430         if (failures == 0)
 431                 pr_info("all %d tests passed!\n", num_tests);
 432         else
 433                 pr_info("failures: %d out of %d\n", failures, num_tests);
 434
 435         return failures ? -EINVAL : 0;
 436 }
 437 module_init(test_meminit_init);
 438
 439 MODULE_DESCRIPTION("Test cases for SL[AOU]B/page initialization at alloc/free time");
 440 MODULE_LICENSE("GPL");