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 /*
 187  * Test kmem_cache with given parameters:
 188  *  want_ctor - use a constructor;
 189  *  want_rcu - use SLAB_TYPESAFE_BY_RCU;
 190  *  want_zero - use __GFP_ZERO.
 191  */
 192 static int __init do_kmem_cache_size(size_t size, bool want_ctor,
 193                                      bool want_rcu, bool want_zero,
 194                                      int *total_failures)
 195 {
 196         struct kmem_cache *c;
 197         int iter;
 198         bool fail = false;
 199         gfp_t alloc_mask = GFP_KERNEL | (want_zero ? __GFP_ZERO : 0);
 200         void *buf, *buf_copy;
 201
 202         c = kmem_cache_create("test_cache", size, 1,
 203                               want_rcu ? SLAB_TYPESAFE_BY_RCU : 0,
 204                               want_ctor ? test_ctor : NULL);
 205         for (iter = 0; iter < 10; iter++) {
 206                 buf = kmem_cache_alloc(c, alloc_mask);
 207                 /* Check that buf is zeroed, if it must be. */
 208                 fail = check_buf(buf, size, want_ctor, want_rcu, want_zero);
 209                 fill_with_garbage_skip(buf, size, want_ctor ? CTOR_BYTES : 0);
 210
 211                 if (!want_rcu) {
 212                         kmem_cache_free(c, buf);
 213                         continue;
 214                 }
 215
 216                 /*
 217                  * If this is an RCU cache, use a critical section to ensure we
 218                  * can touch objects after they're freed.
 219                  */
 220                 rcu_read_lock();
 221                 /*
 222                  * Copy the buffer to check that it's not wiped on
 223                  * free().
 224                  */
 225                 buf_copy = kmalloc(size, GFP_KERNEL);
 226                 if (buf_copy)
 227                         memcpy(buf_copy, buf, size);
 228
 229                 kmem_cache_free(c, buf);
 230                 /*
 231                  * Check that |buf| is intact after kmem_cache_free().
 232                  * |want_zero| is false, because we wrote garbage to
 233                  * the buffer already.
 234                  */
 235                 fail |= check_buf(buf, size, want_ctor, want_rcu,
 236                                   false);
 237                 if (buf_copy) {
 238                         fail |= (bool)memcmp(buf, buf_copy, size);
 239                         kfree(buf_copy);
 240                 }
 241                 rcu_read_unlock();
 242         }
 243         kmem_cache_destroy(c);
 244
 245         *total_failures += fail;
 246         return 1;
 247 }
 248
 249 /*
 250  * Check that the data written to an RCU-allocated object survives
 251  * reallocation.
 252  */
 253 static int __init do_kmem_cache_rcu_persistent(int size, int *total_failures)
 254 {
 255         struct kmem_cache *c;
 256         void *buf, *buf_contents, *saved_ptr;
 257         void **used_objects;
 258         int i, iter, maxiter = 1024;
 259         bool fail = false;
 260
 261         c = kmem_cache_create("test_cache", size, size, SLAB_TYPESAFE_BY_RCU,
 262                               NULL);
 263         buf = kmem_cache_alloc(c, GFP_KERNEL);
 264         saved_ptr = buf;
 265         fill_with_garbage(buf, size);
 266         buf_contents = kmalloc(size, GFP_KERNEL);
 267         if (!buf_contents)
 268                 goto out;
 269         used_objects = kmalloc_array(maxiter, sizeof(void *), GFP_KERNEL);
 270         if (!used_objects) {
 271                 kfree(buf_contents);
 272                 goto out;
 273         }
 274         memcpy(buf_contents, buf, size);
 275         kmem_cache_free(c, buf);
 276         /*
 277          * Run for a fixed number of iterations. If we never hit saved_ptr,
 278          * assume the test passes.
 279          */
 280         for (iter = 0; iter < maxiter; iter++) {
 281                 buf = kmem_cache_alloc(c, GFP_KERNEL);
 282                 used_objects[iter] = buf;
 283                 if (buf == saved_ptr) {
 284                         fail = memcmp(buf_contents, buf, size);
 285                         for (i = 0; i <= iter; i++)
 286                                 kmem_cache_free(c, used_objects[i]);
 287                         goto free_out;
 288                 }
 289         }
 290
 291 free_out:
 292         kmem_cache_destroy(c);
 293         kfree(buf_contents);
 294         kfree(used_objects);
 295 out:
 296         *total_failures += fail;
 297         return 1;
 298 }
 299
 300 /*
 301  * Test kmem_cache allocation by creating caches of different sizes, with and
 302  * without constructors, with and without SLAB_TYPESAFE_BY_RCU.
 303  */
 304 static int __init test_kmemcache(int *total_failures)
 305 {
 306         int failures = 0, num_tests = 0;
 307         int i, flags, size;
 308         bool ctor, rcu, zero;
 309
 310         for (i = 0; i < 10; i++) {
 311                 size = 8 << i;
 312                 for (flags = 0; flags < 8; flags++) {
 313                         ctor = flags & 1;
 314                         rcu = flags & 2;
 315                         zero = flags & 4;
 316                         if (ctor & zero)
 317                                 continue;
 318                         num_tests += do_kmem_cache_size(size, ctor, rcu, zero,
 319                                                         &failures);
 320                 }
 321         }
 322         REPORT_FAILURES_IN_FN();
 323         *total_failures += failures;
 324         return num_tests;
 325 }
 326
 327 /* Test the behavior of SLAB_TYPESAFE_BY_RCU caches of different sizes. */
 328 static int __init test_rcu_persistent(int *total_failures)
 329 {
 330         int failures = 0, num_tests = 0;
 331         int i, size;
 332
 333         for (i = 0; i < 10; i++) {
 334                 size = 8 << i;
 335                 num_tests += do_kmem_cache_rcu_persistent(size, &failures);
 336         }
 337         REPORT_FAILURES_IN_FN();
 338         *total_failures += failures;
 339         return num_tests;
 340 }
 341
 342 /*
 343  * Run the tests. Each test function returns the number of executed tests and
 344  * updates |failures| with the number of failed tests.
 345  */
 346 static int __init test_meminit_init(void)
 347 {
 348         int failures = 0, num_tests = 0;
 349
 350         num_tests += test_pages(&failures);
 351         num_tests += test_kvmalloc(&failures);
 352         num_tests += test_kmemcache(&failures);
 353         num_tests += test_rcu_persistent(&failures);
 354
 355         if (failures == 0)
 356                 pr_info("all %d tests passed!\n", num_tests);
 357         else
 358                 pr_info("failures: %d out of %d\n", failures, num_tests);
 359
 360         return failures ? -EINVAL : 0;
 361 }
 362 module_init(test_meminit_init);
 363
 364 MODULE_LICENSE("GPL");