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. */
count_nonzero_bytes(void * ptr,size_t size)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. */
fill_with_garbage_skip(void * ptr,int size,size_t skip)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
fill_with_garbage(void * ptr,size_t size)58 static void __init fill_with_garbage(void *ptr, size_t size)
59 {
60 fill_with_garbage_skip(ptr, size, 0);
61 }
62
do_alloc_pages_order(int order,int * total_failures)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. */
test_pages(int * total_failures)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 < 10; 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. */
do_kmalloc_size(size_t size,int * total_failures)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. */
do_vmalloc_size(size_t size,int * total_failures)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. */
test_kvmalloc(int * total_failures)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. */
test_ctor(void * obj)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 */
check_buf(void * buf,int size,bool want_ctor,bool want_rcu,bool want_zero)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 */
do_kmem_cache_size(size_t size,bool want_ctor,bool want_rcu,bool want_zero,int * total_failures)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 */
do_kmem_cache_rcu_persistent(int size,int * total_failures)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
do_kmem_cache_size_bulk(int size,int * total_failures)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 */
test_kmemcache(int * total_failures)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. */
test_rcu_persistent(int * total_failures)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 */
test_meminit_init(void)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_LICENSE("GPL");
440
