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 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. */
test_pages(int * total_failures)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. */
do_kmalloc_size(size_t size,int * total_failures)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. */
do_vmalloc_size(size_t size,int * total_failures)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. */
test_kvmalloc(int * total_failures)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. */
test_ctor(void * obj)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 */
check_buf(void * buf,int size,bool want_ctor,bool want_rcu,bool want_zero)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 */
do_kmem_cache_size(size_t size,bool want_ctor,bool want_rcu,bool want_zero,int * total_failures)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_ATOMIC);
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 */
do_kmem_cache_rcu_persistent(int size,int * total_failures)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
do_kmem_cache_size_bulk(int size,int * total_failures)300 static int __init do_kmem_cache_size_bulk(int size, int *total_failures)
301 {
302 struct kmem_cache *c;
303 int i, iter, maxiter = 1024;
304 int num, bytes;
305 bool fail = false;
306 void *objects[10];
307
308 c = kmem_cache_create("test_cache", size, size, 0, NULL);
309 for (iter = 0; (iter < maxiter) && !fail; iter++) {
310 num = kmem_cache_alloc_bulk(c, GFP_KERNEL, ARRAY_SIZE(objects),
311 objects);
312 for (i = 0; i < num; i++) {
313 bytes = count_nonzero_bytes(objects[i], size);
314 if (bytes)
315 fail = true;
316 fill_with_garbage(objects[i], size);
317 }
318
319 if (num)
320 kmem_cache_free_bulk(c, num, objects);
321 }
322 *total_failures += fail;
323 return 1;
324 }
325
326 /*
327 * Test kmem_cache allocation by creating caches of different sizes, with and
328 * without constructors, with and without SLAB_TYPESAFE_BY_RCU.
329 */
test_kmemcache(int * total_failures)330 static int __init test_kmemcache(int *total_failures)
331 {
332 int failures = 0, num_tests = 0;
333 int i, flags, size;
334 bool ctor, rcu, zero;
335
336 for (i = 0; i < 10; i++) {
337 size = 8 << i;
338 for (flags = 0; flags < 8; flags++) {
339 ctor = flags & 1;
340 rcu = flags & 2;
341 zero = flags & 4;
342 if (ctor & zero)
343 continue;
344 num_tests += do_kmem_cache_size(size, ctor, rcu, zero,
345 &failures);
346 }
347 num_tests += do_kmem_cache_size_bulk(size, &failures);
348 }
349 REPORT_FAILURES_IN_FN();
350 *total_failures += failures;
351 return num_tests;
352 }
353
354 /* Test the behavior of SLAB_TYPESAFE_BY_RCU caches of different sizes. */
test_rcu_persistent(int * total_failures)355 static int __init test_rcu_persistent(int *total_failures)
356 {
357 int failures = 0, num_tests = 0;
358 int i, size;
359
360 for (i = 0; i < 10; i++) {
361 size = 8 << i;
362 num_tests += do_kmem_cache_rcu_persistent(size, &failures);
363 }
364 REPORT_FAILURES_IN_FN();
365 *total_failures += failures;
366 return num_tests;
367 }
368
369 /*
370 * Run the tests. Each test function returns the number of executed tests and
371 * updates |failures| with the number of failed tests.
372 */
test_meminit_init(void)373 static int __init test_meminit_init(void)
374 {
375 int failures = 0, num_tests = 0;
376
377 num_tests += test_pages(&failures);
378 num_tests += test_kvmalloc(&failures);
379 num_tests += test_kmemcache(&failures);
380 num_tests += test_rcu_persistent(&failures);
381
382 if (failures == 0)
383 pr_info("all %d tests passed!\n", num_tests);
384 else
385 pr_info("failures: %d out of %d\n", failures, num_tests);
386
387 return failures ? -EINVAL : 0;
388 }
389 module_init(test_meminit_init);
390
391 MODULE_LICENSE("GPL");
392
