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