1 /* binder_alloc_selftest.c
2  *
3  * Android IPC Subsystem
4  *
5  * Copyright (C) 2017 Google, Inc.
6  *
7  * This software is licensed under the terms of the GNU General Public
8  * License version 2, as published by the Free Software Foundation, and
9  * may be copied, distributed, and modified under those terms.
10  *
11  * This program is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14  * GNU General Public License for more details.
15  *
16  */
17 
18 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
19 
20 #include <linux/mm_types.h>
21 #include <linux/err.h>
22 #include "binder_alloc.h"
23 
24 #define BUFFER_NUM 5
25 #define BUFFER_MIN_SIZE (PAGE_SIZE / 8)
26 
27 static bool binder_selftest_run = true;
28 static int binder_selftest_failures;
29 static DEFINE_MUTEX(binder_selftest_lock);
30 
31 /**
32  * enum buf_end_align_type - Page alignment of a buffer
33  * end with regard to the end of the previous buffer.
34  *
35  * In the pictures below, buf2 refers to the buffer we
36  * are aligning. buf1 refers to previous buffer by addr.
37  * Symbol [ means the start of a buffer, ] means the end
38  * of a buffer, and | means page boundaries.
39  */
40 enum buf_end_align_type {
41 	/**
42 	 * @SAME_PAGE_UNALIGNED: The end of this buffer is on
43 	 * the same page as the end of the previous buffer and
44 	 * is not page aligned. Examples:
45 	 * buf1 ][ buf2 ][ ...
46 	 * buf1 ]|[ buf2 ][ ...
47 	 */
48 	SAME_PAGE_UNALIGNED = 0,
49 	/**
50 	 * @SAME_PAGE_ALIGNED: When the end of the previous buffer
51 	 * is not page aligned, the end of this buffer is on the
52 	 * same page as the end of the previous buffer and is page
53 	 * aligned. When the previous buffer is page aligned, the
54 	 * end of this buffer is aligned to the next page boundary.
55 	 * Examples:
56 	 * buf1 ][ buf2 ]| ...
57 	 * buf1 ]|[ buf2 ]| ...
58 	 */
59 	SAME_PAGE_ALIGNED,
60 	/**
61 	 * @NEXT_PAGE_UNALIGNED: The end of this buffer is on
62 	 * the page next to the end of the previous buffer and
63 	 * is not page aligned. Examples:
64 	 * buf1 ][ buf2 | buf2 ][ ...
65 	 * buf1 ]|[ buf2 | buf2 ][ ...
66 	 */
67 	NEXT_PAGE_UNALIGNED,
68 	/**
69 	 * @NEXT_PAGE_ALIGNED: The end of this buffer is on
70 	 * the page next to the end of the previous buffer and
71 	 * is page aligned. Examples:
72 	 * buf1 ][ buf2 | buf2 ]| ...
73 	 * buf1 ]|[ buf2 | buf2 ]| ...
74 	 */
75 	NEXT_PAGE_ALIGNED,
76 	/**
77 	 * @NEXT_NEXT_UNALIGNED: The end of this buffer is on
78 	 * the page that follows the page after the end of the
79 	 * previous buffer and is not page aligned. Examples:
80 	 * buf1 ][ buf2 | buf2 | buf2 ][ ...
81 	 * buf1 ]|[ buf2 | buf2 | buf2 ][ ...
82 	 */
83 	NEXT_NEXT_UNALIGNED,
84 	LOOP_END,
85 };
86 
87 static void pr_err_size_seq(size_t *sizes, int *seq)
88 {
89 	int i;
90 
91 	pr_err("alloc sizes: ");
92 	for (i = 0; i < BUFFER_NUM; i++)
93 		pr_cont("[%zu]", sizes[i]);
94 	pr_cont("\n");
95 	pr_err("free seq: ");
96 	for (i = 0; i < BUFFER_NUM; i++)
97 		pr_cont("[%d]", seq[i]);
98 	pr_cont("\n");
99 }
100 
101 static bool check_buffer_pages_allocated(struct binder_alloc *alloc,
102 					 struct binder_buffer *buffer,
103 					 size_t size)
104 {
105 	void *page_addr, *end;
106 	int page_index;
107 
108 	end = (void *)PAGE_ALIGN((uintptr_t)buffer->data + size);
109 	page_addr = buffer->data;
110 	for (; page_addr < end; page_addr += PAGE_SIZE) {
111 		page_index = (page_addr - alloc->buffer) / PAGE_SIZE;
112 		if (!alloc->pages[page_index].page_ptr ||
113 		    !list_empty(&alloc->pages[page_index].lru)) {
114 			pr_err("expect alloc but is %s at page index %d\n",
115 			       alloc->pages[page_index].page_ptr ?
116 			       "lru" : "free", page_index);
117 			return false;
118 		}
119 	}
120 	return true;
121 }
122 
123 static void binder_selftest_alloc_buf(struct binder_alloc *alloc,
124 				      struct binder_buffer *buffers[],
125 				      size_t *sizes, int *seq)
126 {
127 	int i;
128 
129 	for (i = 0; i < BUFFER_NUM; i++) {
130 		buffers[i] = binder_alloc_new_buf(alloc, sizes[i], 0, 0, 0);
131 		if (IS_ERR(buffers[i]) ||
132 		    !check_buffer_pages_allocated(alloc, buffers[i],
133 						  sizes[i])) {
134 			pr_err_size_seq(sizes, seq);
135 			binder_selftest_failures++;
136 		}
137 	}
138 }
139 
140 static void binder_selftest_free_buf(struct binder_alloc *alloc,
141 				     struct binder_buffer *buffers[],
142 				     size_t *sizes, int *seq, size_t end)
143 {
144 	int i;
145 
146 	for (i = 0; i < BUFFER_NUM; i++)
147 		binder_alloc_free_buf(alloc, buffers[seq[i]]);
148 
149 	for (i = 0; i < end / PAGE_SIZE; i++) {
150 		/**
151 		 * Error message on a free page can be false positive
152 		 * if binder shrinker ran during binder_alloc_free_buf
153 		 * calls above.
154 		 */
155 		if (list_empty(&alloc->pages[i].lru)) {
156 			pr_err_size_seq(sizes, seq);
157 			pr_err("expect lru but is %s at page index %d\n",
158 			       alloc->pages[i].page_ptr ? "alloc" : "free", i);
159 			binder_selftest_failures++;
160 		}
161 	}
162 }
163 
164 static void binder_selftest_free_page(struct binder_alloc *alloc)
165 {
166 	int i;
167 	unsigned long count;
168 
169 	while ((count = list_lru_count(&binder_alloc_lru))) {
170 		list_lru_walk(&binder_alloc_lru, binder_alloc_free_page,
171 			      NULL, count);
172 	}
173 
174 	for (i = 0; i < (alloc->buffer_size / PAGE_SIZE); i++) {
175 		if (alloc->pages[i].page_ptr) {
176 			pr_err("expect free but is %s at page index %d\n",
177 			       list_empty(&alloc->pages[i].lru) ?
178 			       "alloc" : "lru", i);
179 			binder_selftest_failures++;
180 		}
181 	}
182 }
183 
184 static void binder_selftest_alloc_free(struct binder_alloc *alloc,
185 				       size_t *sizes, int *seq, size_t end)
186 {
187 	struct binder_buffer *buffers[BUFFER_NUM];
188 
189 	binder_selftest_alloc_buf(alloc, buffers, sizes, seq);
190 	binder_selftest_free_buf(alloc, buffers, sizes, seq, end);
191 
192 	/* Allocate from lru. */
193 	binder_selftest_alloc_buf(alloc, buffers, sizes, seq);
194 	if (list_lru_count(&binder_alloc_lru))
195 		pr_err("lru list should be empty but is not\n");
196 
197 	binder_selftest_free_buf(alloc, buffers, sizes, seq, end);
198 	binder_selftest_free_page(alloc);
199 }
200 
201 static bool is_dup(int *seq, int index, int val)
202 {
203 	int i;
204 
205 	for (i = 0; i < index; i++) {
206 		if (seq[i] == val)
207 			return true;
208 	}
209 	return false;
210 }
211 
212 /* Generate BUFFER_NUM factorial free orders. */
213 static void binder_selftest_free_seq(struct binder_alloc *alloc,
214 				     size_t *sizes, int *seq,
215 				     int index, size_t end)
216 {
217 	int i;
218 
219 	if (index == BUFFER_NUM) {
220 		binder_selftest_alloc_free(alloc, sizes, seq, end);
221 		return;
222 	}
223 	for (i = 0; i < BUFFER_NUM; i++) {
224 		if (is_dup(seq, index, i))
225 			continue;
226 		seq[index] = i;
227 		binder_selftest_free_seq(alloc, sizes, seq, index + 1, end);
228 	}
229 }
230 
231 static void binder_selftest_alloc_size(struct binder_alloc *alloc,
232 				       size_t *end_offset)
233 {
234 	int i;
235 	int seq[BUFFER_NUM] = {0};
236 	size_t front_sizes[BUFFER_NUM];
237 	size_t back_sizes[BUFFER_NUM];
238 	size_t last_offset, offset = 0;
239 
240 	for (i = 0; i < BUFFER_NUM; i++) {
241 		last_offset = offset;
242 		offset = end_offset[i];
243 		front_sizes[i] = offset - last_offset;
244 		back_sizes[BUFFER_NUM - i - 1] = front_sizes[i];
245 	}
246 	/*
247 	 * Buffers share the first or last few pages.
248 	 * Only BUFFER_NUM - 1 buffer sizes are adjustable since
249 	 * we need one giant buffer before getting to the last page.
250 	 */
251 	back_sizes[0] += alloc->buffer_size - end_offset[BUFFER_NUM - 1];
252 	binder_selftest_free_seq(alloc, front_sizes, seq, 0,
253 				 end_offset[BUFFER_NUM - 1]);
254 	binder_selftest_free_seq(alloc, back_sizes, seq, 0, alloc->buffer_size);
255 }
256 
257 static void binder_selftest_alloc_offset(struct binder_alloc *alloc,
258 					 size_t *end_offset, int index)
259 {
260 	int align;
261 	size_t end, prev;
262 
263 	if (index == BUFFER_NUM) {
264 		binder_selftest_alloc_size(alloc, end_offset);
265 		return;
266 	}
267 	prev = index == 0 ? 0 : end_offset[index - 1];
268 	end = prev;
269 
270 	BUILD_BUG_ON(BUFFER_MIN_SIZE * BUFFER_NUM >= PAGE_SIZE);
271 
272 	for (align = SAME_PAGE_UNALIGNED; align < LOOP_END; align++) {
273 		if (align % 2)
274 			end = ALIGN(end, PAGE_SIZE);
275 		else
276 			end += BUFFER_MIN_SIZE;
277 		end_offset[index] = end;
278 		binder_selftest_alloc_offset(alloc, end_offset, index + 1);
279 	}
280 }
281 
282 /**
283  * binder_selftest_alloc() - Test alloc and free of buffer pages.
284  * @alloc: Pointer to alloc struct.
285  *
286  * Allocate BUFFER_NUM buffers to cover all page alignment cases,
287  * then free them in all orders possible. Check that pages are
288  * correctly allocated, put onto lru when buffers are freed, and
289  * are freed when binder_alloc_free_page is called.
290  */
291 void binder_selftest_alloc(struct binder_alloc *alloc)
292 {
293 	size_t end_offset[BUFFER_NUM];
294 
295 	if (!binder_selftest_run)
296 		return;
297 	mutex_lock(&binder_selftest_lock);
298 	if (!binder_selftest_run || !alloc->vma)
299 		goto done;
300 	pr_info("STARTED\n");
301 	binder_selftest_alloc_offset(alloc, end_offset, 0);
302 	binder_selftest_run = false;
303 	if (binder_selftest_failures > 0)
304 		pr_info("%d tests FAILED\n", binder_selftest_failures);
305 	else
306 		pr_info("PASSED\n");
307 
308 done:
309 	mutex_unlock(&binder_selftest_lock);
310 }
311