xref: /openbmc/linux/lib/test_meminit.c (revision ded1ffea)
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 < 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. */
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