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1 | /* | |
2 | * mm/kmemleak.c | |
3 | * | |
4 | * Copyright (C) 2008 ARM Limited | |
5 | * Written by Catalin Marinas <catalin.marinas@arm.com> | |
6 | * | |
7 | * This program is free software; you can redistribute it and/or modify | |
8 | * it under the terms of the GNU General Public License version 2 as | |
9 | * published by the Free Software Foundation. | |
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 | * You should have received a copy of the GNU General Public License | |
17 | * along with this program; if not, write to the Free Software | |
18 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA | |
19 | * | |
20 | * | |
21 | * For more information on the algorithm and kmemleak usage, please see | |
22 | * Documentation/kmemleak.txt. | |
23 | * | |
24 | * Notes on locking | |
25 | * ---------------- | |
26 | * | |
27 | * The following locks and mutexes are used by kmemleak: | |
28 | * | |
29 | * - kmemleak_lock (rwlock): protects the object_list modifications and | |
30 | * accesses to the object_tree_root. The object_list is the main list | |
31 | * holding the metadata (struct kmemleak_object) for the allocated memory | |
32 | * blocks. The object_tree_root is a red black tree used to look-up | |
33 | * metadata based on a pointer to the corresponding memory block. The | |
34 | * kmemleak_object structures are added to the object_list and | |
35 | * object_tree_root in the create_object() function called from the | |
36 | * kmemleak_alloc() callback and removed in delete_object() called from the | |
37 | * kmemleak_free() callback | |
38 | * - kmemleak_object.lock (spinlock): protects a kmemleak_object. Accesses to | |
39 | * the metadata (e.g. count) are protected by this lock. Note that some | |
40 | * members of this structure may be protected by other means (atomic or | |
41 | * kmemleak_lock). This lock is also held when scanning the corresponding | |
42 | * memory block to avoid the kernel freeing it via the kmemleak_free() | |
43 | * callback. This is less heavyweight than holding a global lock like | |
44 | * kmemleak_lock during scanning | |
45 | * - scan_mutex (mutex): ensures that only one thread may scan the memory for | |
46 | * unreferenced objects at a time. The gray_list contains the objects which | |
47 | * are already referenced or marked as false positives and need to be | |
48 | * scanned. This list is only modified during a scanning episode when the | |
49 | * scan_mutex is held. At the end of a scan, the gray_list is always empty. | |
50 | * Note that the kmemleak_object.use_count is incremented when an object is | |
51 | * added to the gray_list and therefore cannot be freed. This mutex also | |
52 | * prevents multiple users of the "kmemleak" debugfs file together with | |
53 | * modifications to the memory scanning parameters including the scan_thread | |
54 | * pointer | |
55 | * | |
56 | * The kmemleak_object structures have a use_count incremented or decremented | |
57 | * using the get_object()/put_object() functions. When the use_count becomes | |
58 | * 0, this count can no longer be incremented and put_object() schedules the | |
59 | * kmemleak_object freeing via an RCU callback. All calls to the get_object() | |
60 | * function must be protected by rcu_read_lock() to avoid accessing a freed | |
61 | * structure. | |
62 | */ | |
63 | ||
64 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt | |
65 | ||
66 | #include <linux/init.h> | |
67 | #include <linux/kernel.h> | |
68 | #include <linux/list.h> | |
69 | #include <linux/sched.h> | |
70 | #include <linux/jiffies.h> | |
71 | #include <linux/delay.h> | |
72 | #include <linux/export.h> | |
73 | #include <linux/kthread.h> | |
74 | #include <linux/rbtree.h> | |
75 | #include <linux/fs.h> | |
76 | #include <linux/debugfs.h> | |
77 | #include <linux/seq_file.h> | |
78 | #include <linux/cpumask.h> | |
79 | #include <linux/spinlock.h> | |
80 | #include <linux/mutex.h> | |
81 | #include <linux/rcupdate.h> | |
82 | #include <linux/stacktrace.h> | |
83 | #include <linux/cache.h> | |
84 | #include <linux/percpu.h> | |
85 | #include <linux/hardirq.h> | |
86 | #include <linux/mmzone.h> | |
87 | #include <linux/slab.h> | |
88 | #include <linux/thread_info.h> | |
89 | #include <linux/err.h> | |
90 | #include <linux/uaccess.h> | |
91 | #include <linux/string.h> | |
92 | #include <linux/nodemask.h> | |
93 | #include <linux/mm.h> | |
94 | #include <linux/workqueue.h> | |
95 | #include <linux/crc32.h> | |
96 | ||
97 | #include <asm/sections.h> | |
98 | #include <asm/processor.h> | |
99 | #include <linux/atomic.h> | |
100 | ||
101 | #include <linux/kmemcheck.h> | |
102 | #include <linux/kmemleak.h> | |
103 | #include <linux/memory_hotplug.h> | |
104 | ||
105 | /* | |
106 | * Kmemleak configuration and common defines. | |
107 | */ | |
108 | #define MAX_TRACE 16 /* stack trace length */ | |
109 | #define MSECS_MIN_AGE 5000 /* minimum object age for reporting */ | |
110 | #define SECS_FIRST_SCAN 60 /* delay before the first scan */ | |
111 | #define SECS_SCAN_WAIT 600 /* subsequent auto scanning delay */ | |
112 | #define MAX_SCAN_SIZE 4096 /* maximum size of a scanned block */ | |
113 | ||
114 | #define BYTES_PER_POINTER sizeof(void *) | |
115 | ||
116 | /* GFP bitmask for kmemleak internal allocations */ | |
117 | #define gfp_kmemleak_mask(gfp) (((gfp) & (GFP_KERNEL | GFP_ATOMIC)) | \ | |
118 | __GFP_NORETRY | __GFP_NOMEMALLOC | \ | |
119 | __GFP_NOWARN) | |
120 | ||
121 | /* scanning area inside a memory block */ | |
122 | struct kmemleak_scan_area { | |
123 | struct hlist_node node; | |
124 | unsigned long start; | |
125 | size_t size; | |
126 | }; | |
127 | ||
128 | #define KMEMLEAK_GREY 0 | |
129 | #define KMEMLEAK_BLACK -1 | |
130 | ||
131 | /* | |
132 | * Structure holding the metadata for each allocated memory block. | |
133 | * Modifications to such objects should be made while holding the | |
134 | * object->lock. Insertions or deletions from object_list, gray_list or | |
135 | * rb_node are already protected by the corresponding locks or mutex (see | |
136 | * the notes on locking above). These objects are reference-counted | |
137 | * (use_count) and freed using the RCU mechanism. | |
138 | */ | |
139 | struct kmemleak_object { | |
140 | spinlock_t lock; | |
141 | unsigned long flags; /* object status flags */ | |
142 | struct list_head object_list; | |
143 | struct list_head gray_list; | |
144 | struct rb_node rb_node; | |
145 | struct rcu_head rcu; /* object_list lockless traversal */ | |
146 | /* object usage count; object freed when use_count == 0 */ | |
147 | atomic_t use_count; | |
148 | unsigned long pointer; | |
149 | size_t size; | |
150 | /* minimum number of a pointers found before it is considered leak */ | |
151 | int min_count; | |
152 | /* the total number of pointers found pointing to this object */ | |
153 | int count; | |
154 | /* checksum for detecting modified objects */ | |
155 | u32 checksum; | |
156 | /* memory ranges to be scanned inside an object (empty for all) */ | |
157 | struct hlist_head area_list; | |
158 | unsigned long trace[MAX_TRACE]; | |
159 | unsigned int trace_len; | |
160 | unsigned long jiffies; /* creation timestamp */ | |
161 | pid_t pid; /* pid of the current task */ | |
162 | char comm[TASK_COMM_LEN]; /* executable name */ | |
163 | }; | |
164 | ||
165 | /* flag representing the memory block allocation status */ | |
166 | #define OBJECT_ALLOCATED (1 << 0) | |
167 | /* flag set after the first reporting of an unreference object */ | |
168 | #define OBJECT_REPORTED (1 << 1) | |
169 | /* flag set to not scan the object */ | |
170 | #define OBJECT_NO_SCAN (1 << 2) | |
171 | ||
172 | /* number of bytes to print per line; must be 16 or 32 */ | |
173 | #define HEX_ROW_SIZE 16 | |
174 | /* number of bytes to print at a time (1, 2, 4, 8) */ | |
175 | #define HEX_GROUP_SIZE 1 | |
176 | /* include ASCII after the hex output */ | |
177 | #define HEX_ASCII 1 | |
178 | /* max number of lines to be printed */ | |
179 | #define HEX_MAX_LINES 2 | |
180 | ||
181 | /* the list of all allocated objects */ | |
182 | static LIST_HEAD(object_list); | |
183 | /* the list of gray-colored objects (see color_gray comment below) */ | |
184 | static LIST_HEAD(gray_list); | |
185 | /* search tree for object boundaries */ | |
186 | static struct rb_root object_tree_root = RB_ROOT; | |
187 | /* rw_lock protecting the access to object_list and object_tree_root */ | |
188 | static DEFINE_RWLOCK(kmemleak_lock); | |
189 | ||
190 | /* allocation caches for kmemleak internal data */ | |
191 | static struct kmem_cache *object_cache; | |
192 | static struct kmem_cache *scan_area_cache; | |
193 | ||
194 | /* set if tracing memory operations is enabled */ | |
195 | static atomic_t kmemleak_enabled = ATOMIC_INIT(0); | |
196 | /* set in the late_initcall if there were no errors */ | |
197 | static atomic_t kmemleak_initialized = ATOMIC_INIT(0); | |
198 | /* enables or disables early logging of the memory operations */ | |
199 | static atomic_t kmemleak_early_log = ATOMIC_INIT(1); | |
200 | /* set if a kmemleak warning was issued */ | |
201 | static atomic_t kmemleak_warning = ATOMIC_INIT(0); | |
202 | /* set if a fatal kmemleak error has occurred */ | |
203 | static atomic_t kmemleak_error = ATOMIC_INIT(0); | |
204 | ||
205 | /* minimum and maximum address that may be valid pointers */ | |
206 | static unsigned long min_addr = ULONG_MAX; | |
207 | static unsigned long max_addr; | |
208 | ||
209 | static struct task_struct *scan_thread; | |
210 | /* used to avoid reporting of recently allocated objects */ | |
211 | static unsigned long jiffies_min_age; | |
212 | static unsigned long jiffies_last_scan; | |
213 | /* delay between automatic memory scannings */ | |
214 | static signed long jiffies_scan_wait; | |
215 | /* enables or disables the task stacks scanning */ | |
216 | static int kmemleak_stack_scan = 1; | |
217 | /* protects the memory scanning, parameters and debug/kmemleak file access */ | |
218 | static DEFINE_MUTEX(scan_mutex); | |
219 | /* setting kmemleak=on, will set this var, skipping the disable */ | |
220 | static int kmemleak_skip_disable; | |
221 | ||
222 | ||
223 | /* | |
224 | * Early object allocation/freeing logging. Kmemleak is initialized after the | |
225 | * kernel allocator. However, both the kernel allocator and kmemleak may | |
226 | * allocate memory blocks which need to be tracked. Kmemleak defines an | |
227 | * arbitrary buffer to hold the allocation/freeing information before it is | |
228 | * fully initialized. | |
229 | */ | |
230 | ||
231 | /* kmemleak operation type for early logging */ | |
232 | enum { | |
233 | KMEMLEAK_ALLOC, | |
234 | KMEMLEAK_ALLOC_PERCPU, | |
235 | KMEMLEAK_FREE, | |
236 | KMEMLEAK_FREE_PART, | |
237 | KMEMLEAK_FREE_PERCPU, | |
238 | KMEMLEAK_NOT_LEAK, | |
239 | KMEMLEAK_IGNORE, | |
240 | KMEMLEAK_SCAN_AREA, | |
241 | KMEMLEAK_NO_SCAN | |
242 | }; | |
243 | ||
244 | /* | |
245 | * Structure holding the information passed to kmemleak callbacks during the | |
246 | * early logging. | |
247 | */ | |
248 | struct early_log { | |
249 | int op_type; /* kmemleak operation type */ | |
250 | const void *ptr; /* allocated/freed memory block */ | |
251 | size_t size; /* memory block size */ | |
252 | int min_count; /* minimum reference count */ | |
253 | unsigned long trace[MAX_TRACE]; /* stack trace */ | |
254 | unsigned int trace_len; /* stack trace length */ | |
255 | }; | |
256 | ||
257 | /* early logging buffer and current position */ | |
258 | static struct early_log | |
259 | early_log[CONFIG_DEBUG_KMEMLEAK_EARLY_LOG_SIZE] __initdata; | |
260 | static int crt_early_log __initdata; | |
261 | ||
262 | static void kmemleak_disable(void); | |
263 | ||
264 | /* | |
265 | * Print a warning and dump the stack trace. | |
266 | */ | |
267 | #define kmemleak_warn(x...) do { \ | |
268 | pr_warning(x); \ | |
269 | dump_stack(); \ | |
270 | atomic_set(&kmemleak_warning, 1); \ | |
271 | } while (0) | |
272 | ||
273 | /* | |
274 | * Macro invoked when a serious kmemleak condition occurred and cannot be | |
275 | * recovered from. Kmemleak will be disabled and further allocation/freeing | |
276 | * tracing no longer available. | |
277 | */ | |
278 | #define kmemleak_stop(x...) do { \ | |
279 | kmemleak_warn(x); \ | |
280 | kmemleak_disable(); \ | |
281 | } while (0) | |
282 | ||
283 | /* | |
284 | * Printing of the objects hex dump to the seq file. The number of lines to be | |
285 | * printed is limited to HEX_MAX_LINES to prevent seq file spamming. The | |
286 | * actual number of printed bytes depends on HEX_ROW_SIZE. It must be called | |
287 | * with the object->lock held. | |
288 | */ | |
289 | static void hex_dump_object(struct seq_file *seq, | |
290 | struct kmemleak_object *object) | |
291 | { | |
292 | const u8 *ptr = (const u8 *)object->pointer; | |
293 | int i, len, remaining; | |
294 | unsigned char linebuf[HEX_ROW_SIZE * 5]; | |
295 | ||
296 | /* limit the number of lines to HEX_MAX_LINES */ | |
297 | remaining = len = | |
298 | min(object->size, (size_t)(HEX_MAX_LINES * HEX_ROW_SIZE)); | |
299 | ||
300 | seq_printf(seq, " hex dump (first %d bytes):\n", len); | |
301 | for (i = 0; i < len; i += HEX_ROW_SIZE) { | |
302 | int linelen = min(remaining, HEX_ROW_SIZE); | |
303 | ||
304 | remaining -= HEX_ROW_SIZE; | |
305 | hex_dump_to_buffer(ptr + i, linelen, HEX_ROW_SIZE, | |
306 | HEX_GROUP_SIZE, linebuf, sizeof(linebuf), | |
307 | HEX_ASCII); | |
308 | seq_printf(seq, " %s\n", linebuf); | |
309 | } | |
310 | } | |
311 | ||
312 | /* | |
313 | * Object colors, encoded with count and min_count: | |
314 | * - white - orphan object, not enough references to it (count < min_count) | |
315 | * - gray - not orphan, not marked as false positive (min_count == 0) or | |
316 | * sufficient references to it (count >= min_count) | |
317 | * - black - ignore, it doesn't contain references (e.g. text section) | |
318 | * (min_count == -1). No function defined for this color. | |
319 | * Newly created objects don't have any color assigned (object->count == -1) | |
320 | * before the next memory scan when they become white. | |
321 | */ | |
322 | static bool color_white(const struct kmemleak_object *object) | |
323 | { | |
324 | return object->count != KMEMLEAK_BLACK && | |
325 | object->count < object->min_count; | |
326 | } | |
327 | ||
328 | static bool color_gray(const struct kmemleak_object *object) | |
329 | { | |
330 | return object->min_count != KMEMLEAK_BLACK && | |
331 | object->count >= object->min_count; | |
332 | } | |
333 | ||
334 | /* | |
335 | * Objects are considered unreferenced only if their color is white, they have | |
336 | * not be deleted and have a minimum age to avoid false positives caused by | |
337 | * pointers temporarily stored in CPU registers. | |
338 | */ | |
339 | static bool unreferenced_object(struct kmemleak_object *object) | |
340 | { | |
341 | return (color_white(object) && object->flags & OBJECT_ALLOCATED) && | |
342 | time_before_eq(object->jiffies + jiffies_min_age, | |
343 | jiffies_last_scan); | |
344 | } | |
345 | ||
346 | /* | |
347 | * Printing of the unreferenced objects information to the seq file. The | |
348 | * print_unreferenced function must be called with the object->lock held. | |
349 | */ | |
350 | static void print_unreferenced(struct seq_file *seq, | |
351 | struct kmemleak_object *object) | |
352 | { | |
353 | int i; | |
354 | unsigned int msecs_age = jiffies_to_msecs(jiffies - object->jiffies); | |
355 | ||
356 | seq_printf(seq, "unreferenced object 0x%08lx (size %zu):\n", | |
357 | object->pointer, object->size); | |
358 | seq_printf(seq, " comm \"%s\", pid %d, jiffies %lu (age %d.%03ds)\n", | |
359 | object->comm, object->pid, object->jiffies, | |
360 | msecs_age / 1000, msecs_age % 1000); | |
361 | hex_dump_object(seq, object); | |
362 | seq_printf(seq, " backtrace:\n"); | |
363 | ||
364 | for (i = 0; i < object->trace_len; i++) { | |
365 | void *ptr = (void *)object->trace[i]; | |
366 | seq_printf(seq, " [<%p>] %pS\n", ptr, ptr); | |
367 | } | |
368 | } | |
369 | ||
370 | /* | |
371 | * Print the kmemleak_object information. This function is used mainly for | |
372 | * debugging special cases when kmemleak operations. It must be called with | |
373 | * the object->lock held. | |
374 | */ | |
375 | static void dump_object_info(struct kmemleak_object *object) | |
376 | { | |
377 | struct stack_trace trace; | |
378 | ||
379 | trace.nr_entries = object->trace_len; | |
380 | trace.entries = object->trace; | |
381 | ||
382 | pr_notice("Object 0x%08lx (size %zu):\n", | |
383 | object->pointer, object->size); | |
384 | pr_notice(" comm \"%s\", pid %d, jiffies %lu\n", | |
385 | object->comm, object->pid, object->jiffies); | |
386 | pr_notice(" min_count = %d\n", object->min_count); | |
387 | pr_notice(" count = %d\n", object->count); | |
388 | pr_notice(" flags = 0x%lx\n", object->flags); | |
389 | pr_notice(" checksum = %d\n", object->checksum); | |
390 | pr_notice(" backtrace:\n"); | |
391 | print_stack_trace(&trace, 4); | |
392 | } | |
393 | ||
394 | /* | |
395 | * Look-up a memory block metadata (kmemleak_object) in the object search | |
396 | * tree based on a pointer value. If alias is 0, only values pointing to the | |
397 | * beginning of the memory block are allowed. The kmemleak_lock must be held | |
398 | * when calling this function. | |
399 | */ | |
400 | static struct kmemleak_object *lookup_object(unsigned long ptr, int alias) | |
401 | { | |
402 | struct rb_node *rb = object_tree_root.rb_node; | |
403 | ||
404 | while (rb) { | |
405 | struct kmemleak_object *object = | |
406 | rb_entry(rb, struct kmemleak_object, rb_node); | |
407 | if (ptr < object->pointer) | |
408 | rb = object->rb_node.rb_left; | |
409 | else if (object->pointer + object->size <= ptr) | |
410 | rb = object->rb_node.rb_right; | |
411 | else if (object->pointer == ptr || alias) | |
412 | return object; | |
413 | else { | |
414 | kmemleak_warn("Found object by alias at 0x%08lx\n", | |
415 | ptr); | |
416 | dump_object_info(object); | |
417 | break; | |
418 | } | |
419 | } | |
420 | return NULL; | |
421 | } | |
422 | ||
423 | /* | |
424 | * Increment the object use_count. Return 1 if successful or 0 otherwise. Note | |
425 | * that once an object's use_count reached 0, the RCU freeing was already | |
426 | * registered and the object should no longer be used. This function must be | |
427 | * called under the protection of rcu_read_lock(). | |
428 | */ | |
429 | static int get_object(struct kmemleak_object *object) | |
430 | { | |
431 | return atomic_inc_not_zero(&object->use_count); | |
432 | } | |
433 | ||
434 | /* | |
435 | * RCU callback to free a kmemleak_object. | |
436 | */ | |
437 | static void free_object_rcu(struct rcu_head *rcu) | |
438 | { | |
439 | struct hlist_node *tmp; | |
440 | struct kmemleak_scan_area *area; | |
441 | struct kmemleak_object *object = | |
442 | container_of(rcu, struct kmemleak_object, rcu); | |
443 | ||
444 | /* | |
445 | * Once use_count is 0 (guaranteed by put_object), there is no other | |
446 | * code accessing this object, hence no need for locking. | |
447 | */ | |
448 | hlist_for_each_entry_safe(area, tmp, &object->area_list, node) { | |
449 | hlist_del(&area->node); | |
450 | kmem_cache_free(scan_area_cache, area); | |
451 | } | |
452 | kmem_cache_free(object_cache, object); | |
453 | } | |
454 | ||
455 | /* | |
456 | * Decrement the object use_count. Once the count is 0, free the object using | |
457 | * an RCU callback. Since put_object() may be called via the kmemleak_free() -> | |
458 | * delete_object() path, the delayed RCU freeing ensures that there is no | |
459 | * recursive call to the kernel allocator. Lock-less RCU object_list traversal | |
460 | * is also possible. | |
461 | */ | |
462 | static void put_object(struct kmemleak_object *object) | |
463 | { | |
464 | if (!atomic_dec_and_test(&object->use_count)) | |
465 | return; | |
466 | ||
467 | /* should only get here after delete_object was called */ | |
468 | WARN_ON(object->flags & OBJECT_ALLOCATED); | |
469 | ||
470 | call_rcu(&object->rcu, free_object_rcu); | |
471 | } | |
472 | ||
473 | /* | |
474 | * Look up an object in the object search tree and increase its use_count. | |
475 | */ | |
476 | static struct kmemleak_object *find_and_get_object(unsigned long ptr, int alias) | |
477 | { | |
478 | unsigned long flags; | |
479 | struct kmemleak_object *object = NULL; | |
480 | ||
481 | rcu_read_lock(); | |
482 | read_lock_irqsave(&kmemleak_lock, flags); | |
483 | if (ptr >= min_addr && ptr < max_addr) | |
484 | object = lookup_object(ptr, alias); | |
485 | read_unlock_irqrestore(&kmemleak_lock, flags); | |
486 | ||
487 | /* check whether the object is still available */ | |
488 | if (object && !get_object(object)) | |
489 | object = NULL; | |
490 | rcu_read_unlock(); | |
491 | ||
492 | return object; | |
493 | } | |
494 | ||
495 | /* | |
496 | * Save stack trace to the given array of MAX_TRACE size. | |
497 | */ | |
498 | static int __save_stack_trace(unsigned long *trace) | |
499 | { | |
500 | struct stack_trace stack_trace; | |
501 | ||
502 | stack_trace.max_entries = MAX_TRACE; | |
503 | stack_trace.nr_entries = 0; | |
504 | stack_trace.entries = trace; | |
505 | stack_trace.skip = 2; | |
506 | save_stack_trace(&stack_trace); | |
507 | ||
508 | return stack_trace.nr_entries; | |
509 | } | |
510 | ||
511 | /* | |
512 | * Create the metadata (struct kmemleak_object) corresponding to an allocated | |
513 | * memory block and add it to the object_list and object_tree_root. | |
514 | */ | |
515 | static struct kmemleak_object *create_object(unsigned long ptr, size_t size, | |
516 | int min_count, gfp_t gfp) | |
517 | { | |
518 | unsigned long flags; | |
519 | struct kmemleak_object *object, *parent; | |
520 | struct rb_node **link, *rb_parent; | |
521 | ||
522 | object = kmem_cache_alloc(object_cache, gfp_kmemleak_mask(gfp)); | |
523 | if (!object) { | |
524 | pr_warning("Cannot allocate a kmemleak_object structure\n"); | |
525 | kmemleak_disable(); | |
526 | return NULL; | |
527 | } | |
528 | ||
529 | INIT_LIST_HEAD(&object->object_list); | |
530 | INIT_LIST_HEAD(&object->gray_list); | |
531 | INIT_HLIST_HEAD(&object->area_list); | |
532 | spin_lock_init(&object->lock); | |
533 | atomic_set(&object->use_count, 1); | |
534 | object->flags = OBJECT_ALLOCATED; | |
535 | object->pointer = ptr; | |
536 | object->size = size; | |
537 | object->min_count = min_count; | |
538 | object->count = 0; /* white color initially */ | |
539 | object->jiffies = jiffies; | |
540 | object->checksum = 0; | |
541 | ||
542 | /* task information */ | |
543 | if (in_irq()) { | |
544 | object->pid = 0; | |
545 | strncpy(object->comm, "hardirq", sizeof(object->comm)); | |
546 | } else if (in_softirq()) { | |
547 | object->pid = 0; | |
548 | strncpy(object->comm, "softirq", sizeof(object->comm)); | |
549 | } else { | |
550 | object->pid = current->pid; | |
551 | /* | |
552 | * There is a small chance of a race with set_task_comm(), | |
553 | * however using get_task_comm() here may cause locking | |
554 | * dependency issues with current->alloc_lock. In the worst | |
555 | * case, the command line is not correct. | |
556 | */ | |
557 | strncpy(object->comm, current->comm, sizeof(object->comm)); | |
558 | } | |
559 | ||
560 | /* kernel backtrace */ | |
561 | object->trace_len = __save_stack_trace(object->trace); | |
562 | ||
563 | write_lock_irqsave(&kmemleak_lock, flags); | |
564 | ||
565 | min_addr = min(min_addr, ptr); | |
566 | max_addr = max(max_addr, ptr + size); | |
567 | link = &object_tree_root.rb_node; | |
568 | rb_parent = NULL; | |
569 | while (*link) { | |
570 | rb_parent = *link; | |
571 | parent = rb_entry(rb_parent, struct kmemleak_object, rb_node); | |
572 | if (ptr + size <= parent->pointer) | |
573 | link = &parent->rb_node.rb_left; | |
574 | else if (parent->pointer + parent->size <= ptr) | |
575 | link = &parent->rb_node.rb_right; | |
576 | else { | |
577 | kmemleak_stop("Cannot insert 0x%lx into the object " | |
578 | "search tree (overlaps existing)\n", | |
579 | ptr); | |
580 | kmem_cache_free(object_cache, object); | |
581 | object = parent; | |
582 | spin_lock(&object->lock); | |
583 | dump_object_info(object); | |
584 | spin_unlock(&object->lock); | |
585 | goto out; | |
586 | } | |
587 | } | |
588 | rb_link_node(&object->rb_node, rb_parent, link); | |
589 | rb_insert_color(&object->rb_node, &object_tree_root); | |
590 | ||
591 | list_add_tail_rcu(&object->object_list, &object_list); | |
592 | out: | |
593 | write_unlock_irqrestore(&kmemleak_lock, flags); | |
594 | return object; | |
595 | } | |
596 | ||
597 | /* | |
598 | * Remove the metadata (struct kmemleak_object) for a memory block from the | |
599 | * object_list and object_tree_root and decrement its use_count. | |
600 | */ | |
601 | static void __delete_object(struct kmemleak_object *object) | |
602 | { | |
603 | unsigned long flags; | |
604 | ||
605 | write_lock_irqsave(&kmemleak_lock, flags); | |
606 | rb_erase(&object->rb_node, &object_tree_root); | |
607 | list_del_rcu(&object->object_list); | |
608 | write_unlock_irqrestore(&kmemleak_lock, flags); | |
609 | ||
610 | WARN_ON(!(object->flags & OBJECT_ALLOCATED)); | |
611 | WARN_ON(atomic_read(&object->use_count) < 2); | |
612 | ||
613 | /* | |
614 | * Locking here also ensures that the corresponding memory block | |
615 | * cannot be freed when it is being scanned. | |
616 | */ | |
617 | spin_lock_irqsave(&object->lock, flags); | |
618 | object->flags &= ~OBJECT_ALLOCATED; | |
619 | spin_unlock_irqrestore(&object->lock, flags); | |
620 | put_object(object); | |
621 | } | |
622 | ||
623 | /* | |
624 | * Look up the metadata (struct kmemleak_object) corresponding to ptr and | |
625 | * delete it. | |
626 | */ | |
627 | static void delete_object_full(unsigned long ptr) | |
628 | { | |
629 | struct kmemleak_object *object; | |
630 | ||
631 | object = find_and_get_object(ptr, 0); | |
632 | if (!object) { | |
633 | #ifdef DEBUG | |
634 | kmemleak_warn("Freeing unknown object at 0x%08lx\n", | |
635 | ptr); | |
636 | #endif | |
637 | return; | |
638 | } | |
639 | __delete_object(object); | |
640 | put_object(object); | |
641 | } | |
642 | ||
643 | /* | |
644 | * Look up the metadata (struct kmemleak_object) corresponding to ptr and | |
645 | * delete it. If the memory block is partially freed, the function may create | |
646 | * additional metadata for the remaining parts of the block. | |
647 | */ | |
648 | static void delete_object_part(unsigned long ptr, size_t size) | |
649 | { | |
650 | struct kmemleak_object *object; | |
651 | unsigned long start, end; | |
652 | ||
653 | object = find_and_get_object(ptr, 1); | |
654 | if (!object) { | |
655 | #ifdef DEBUG | |
656 | kmemleak_warn("Partially freeing unknown object at 0x%08lx " | |
657 | "(size %zu)\n", ptr, size); | |
658 | #endif | |
659 | return; | |
660 | } | |
661 | __delete_object(object); | |
662 | ||
663 | /* | |
664 | * Create one or two objects that may result from the memory block | |
665 | * split. Note that partial freeing is only done by free_bootmem() and | |
666 | * this happens before kmemleak_init() is called. The path below is | |
667 | * only executed during early log recording in kmemleak_init(), so | |
668 | * GFP_KERNEL is enough. | |
669 | */ | |
670 | start = object->pointer; | |
671 | end = object->pointer + object->size; | |
672 | if (ptr > start) | |
673 | create_object(start, ptr - start, object->min_count, | |
674 | GFP_KERNEL); | |
675 | if (ptr + size < end) | |
676 | create_object(ptr + size, end - ptr - size, object->min_count, | |
677 | GFP_KERNEL); | |
678 | ||
679 | put_object(object); | |
680 | } | |
681 | ||
682 | static void __paint_it(struct kmemleak_object *object, int color) | |
683 | { | |
684 | object->min_count = color; | |
685 | if (color == KMEMLEAK_BLACK) | |
686 | object->flags |= OBJECT_NO_SCAN; | |
687 | } | |
688 | ||
689 | static void paint_it(struct kmemleak_object *object, int color) | |
690 | { | |
691 | unsigned long flags; | |
692 | ||
693 | spin_lock_irqsave(&object->lock, flags); | |
694 | __paint_it(object, color); | |
695 | spin_unlock_irqrestore(&object->lock, flags); | |
696 | } | |
697 | ||
698 | static void paint_ptr(unsigned long ptr, int color) | |
699 | { | |
700 | struct kmemleak_object *object; | |
701 | ||
702 | object = find_and_get_object(ptr, 0); | |
703 | if (!object) { | |
704 | kmemleak_warn("Trying to color unknown object " | |
705 | "at 0x%08lx as %s\n", ptr, | |
706 | (color == KMEMLEAK_GREY) ? "Grey" : | |
707 | (color == KMEMLEAK_BLACK) ? "Black" : "Unknown"); | |
708 | return; | |
709 | } | |
710 | paint_it(object, color); | |
711 | put_object(object); | |
712 | } | |
713 | ||
714 | /* | |
715 | * Mark an object permanently as gray-colored so that it can no longer be | |
716 | * reported as a leak. This is used in general to mark a false positive. | |
717 | */ | |
718 | static void make_gray_object(unsigned long ptr) | |
719 | { | |
720 | paint_ptr(ptr, KMEMLEAK_GREY); | |
721 | } | |
722 | ||
723 | /* | |
724 | * Mark the object as black-colored so that it is ignored from scans and | |
725 | * reporting. | |
726 | */ | |
727 | static void make_black_object(unsigned long ptr) | |
728 | { | |
729 | paint_ptr(ptr, KMEMLEAK_BLACK); | |
730 | } | |
731 | ||
732 | /* | |
733 | * Add a scanning area to the object. If at least one such area is added, | |
734 | * kmemleak will only scan these ranges rather than the whole memory block. | |
735 | */ | |
736 | static void add_scan_area(unsigned long ptr, size_t size, gfp_t gfp) | |
737 | { | |
738 | unsigned long flags; | |
739 | struct kmemleak_object *object; | |
740 | struct kmemleak_scan_area *area; | |
741 | ||
742 | object = find_and_get_object(ptr, 1); | |
743 | if (!object) { | |
744 | kmemleak_warn("Adding scan area to unknown object at 0x%08lx\n", | |
745 | ptr); | |
746 | return; | |
747 | } | |
748 | ||
749 | area = kmem_cache_alloc(scan_area_cache, gfp_kmemleak_mask(gfp)); | |
750 | if (!area) { | |
751 | pr_warning("Cannot allocate a scan area\n"); | |
752 | goto out; | |
753 | } | |
754 | ||
755 | spin_lock_irqsave(&object->lock, flags); | |
756 | if (size == SIZE_MAX) { | |
757 | size = object->pointer + object->size - ptr; | |
758 | } else if (ptr + size > object->pointer + object->size) { | |
759 | kmemleak_warn("Scan area larger than object 0x%08lx\n", ptr); | |
760 | dump_object_info(object); | |
761 | kmem_cache_free(scan_area_cache, area); | |
762 | goto out_unlock; | |
763 | } | |
764 | ||
765 | INIT_HLIST_NODE(&area->node); | |
766 | area->start = ptr; | |
767 | area->size = size; | |
768 | ||
769 | hlist_add_head(&area->node, &object->area_list); | |
770 | out_unlock: | |
771 | spin_unlock_irqrestore(&object->lock, flags); | |
772 | out: | |
773 | put_object(object); | |
774 | } | |
775 | ||
776 | /* | |
777 | * Set the OBJECT_NO_SCAN flag for the object corresponding to the give | |
778 | * pointer. Such object will not be scanned by kmemleak but references to it | |
779 | * are searched. | |
780 | */ | |
781 | static void object_no_scan(unsigned long ptr) | |
782 | { | |
783 | unsigned long flags; | |
784 | struct kmemleak_object *object; | |
785 | ||
786 | object = find_and_get_object(ptr, 0); | |
787 | if (!object) { | |
788 | kmemleak_warn("Not scanning unknown object at 0x%08lx\n", ptr); | |
789 | return; | |
790 | } | |
791 | ||
792 | spin_lock_irqsave(&object->lock, flags); | |
793 | object->flags |= OBJECT_NO_SCAN; | |
794 | spin_unlock_irqrestore(&object->lock, flags); | |
795 | put_object(object); | |
796 | } | |
797 | ||
798 | /* | |
799 | * Log an early kmemleak_* call to the early_log buffer. These calls will be | |
800 | * processed later once kmemleak is fully initialized. | |
801 | */ | |
802 | static void __init log_early(int op_type, const void *ptr, size_t size, | |
803 | int min_count) | |
804 | { | |
805 | unsigned long flags; | |
806 | struct early_log *log; | |
807 | ||
808 | if (atomic_read(&kmemleak_error)) { | |
809 | /* kmemleak stopped recording, just count the requests */ | |
810 | crt_early_log++; | |
811 | return; | |
812 | } | |
813 | ||
814 | if (crt_early_log >= ARRAY_SIZE(early_log)) { | |
815 | kmemleak_disable(); | |
816 | return; | |
817 | } | |
818 | ||
819 | /* | |
820 | * There is no need for locking since the kernel is still in UP mode | |
821 | * at this stage. Disabling the IRQs is enough. | |
822 | */ | |
823 | local_irq_save(flags); | |
824 | log = &early_log[crt_early_log]; | |
825 | log->op_type = op_type; | |
826 | log->ptr = ptr; | |
827 | log->size = size; | |
828 | log->min_count = min_count; | |
829 | log->trace_len = __save_stack_trace(log->trace); | |
830 | crt_early_log++; | |
831 | local_irq_restore(flags); | |
832 | } | |
833 | ||
834 | /* | |
835 | * Log an early allocated block and populate the stack trace. | |
836 | */ | |
837 | static void early_alloc(struct early_log *log) | |
838 | { | |
839 | struct kmemleak_object *object; | |
840 | unsigned long flags; | |
841 | int i; | |
842 | ||
843 | if (!atomic_read(&kmemleak_enabled) || !log->ptr || IS_ERR(log->ptr)) | |
844 | return; | |
845 | ||
846 | /* | |
847 | * RCU locking needed to ensure object is not freed via put_object(). | |
848 | */ | |
849 | rcu_read_lock(); | |
850 | object = create_object((unsigned long)log->ptr, log->size, | |
851 | log->min_count, GFP_ATOMIC); | |
852 | if (!object) | |
853 | goto out; | |
854 | spin_lock_irqsave(&object->lock, flags); | |
855 | for (i = 0; i < log->trace_len; i++) | |
856 | object->trace[i] = log->trace[i]; | |
857 | object->trace_len = log->trace_len; | |
858 | spin_unlock_irqrestore(&object->lock, flags); | |
859 | out: | |
860 | rcu_read_unlock(); | |
861 | } | |
862 | ||
863 | /* | |
864 | * Log an early allocated block and populate the stack trace. | |
865 | */ | |
866 | static void early_alloc_percpu(struct early_log *log) | |
867 | { | |
868 | unsigned int cpu; | |
869 | const void __percpu *ptr = log->ptr; | |
870 | ||
871 | for_each_possible_cpu(cpu) { | |
872 | log->ptr = per_cpu_ptr(ptr, cpu); | |
873 | early_alloc(log); | |
874 | } | |
875 | } | |
876 | ||
877 | /** | |
878 | * kmemleak_alloc - register a newly allocated object | |
879 | * @ptr: pointer to beginning of the object | |
880 | * @size: size of the object | |
881 | * @min_count: minimum number of references to this object. If during memory | |
882 | * scanning a number of references less than @min_count is found, | |
883 | * the object is reported as a memory leak. If @min_count is 0, | |
884 | * the object is never reported as a leak. If @min_count is -1, | |
885 | * the object is ignored (not scanned and not reported as a leak) | |
886 | * @gfp: kmalloc() flags used for kmemleak internal memory allocations | |
887 | * | |
888 | * This function is called from the kernel allocators when a new object | |
889 | * (memory block) is allocated (kmem_cache_alloc, kmalloc, vmalloc etc.). | |
890 | */ | |
891 | void __ref kmemleak_alloc(const void *ptr, size_t size, int min_count, | |
892 | gfp_t gfp) | |
893 | { | |
894 | pr_debug("%s(0x%p, %zu, %d)\n", __func__, ptr, size, min_count); | |
895 | ||
896 | if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr)) | |
897 | create_object((unsigned long)ptr, size, min_count, gfp); | |
898 | else if (atomic_read(&kmemleak_early_log)) | |
899 | log_early(KMEMLEAK_ALLOC, ptr, size, min_count); | |
900 | } | |
901 | EXPORT_SYMBOL_GPL(kmemleak_alloc); | |
902 | ||
903 | /** | |
904 | * kmemleak_alloc_percpu - register a newly allocated __percpu object | |
905 | * @ptr: __percpu pointer to beginning of the object | |
906 | * @size: size of the object | |
907 | * | |
908 | * This function is called from the kernel percpu allocator when a new object | |
909 | * (memory block) is allocated (alloc_percpu). It assumes GFP_KERNEL | |
910 | * allocation. | |
911 | */ | |
912 | void __ref kmemleak_alloc_percpu(const void __percpu *ptr, size_t size) | |
913 | { | |
914 | unsigned int cpu; | |
915 | ||
916 | pr_debug("%s(0x%p, %zu)\n", __func__, ptr, size); | |
917 | ||
918 | /* | |
919 | * Percpu allocations are only scanned and not reported as leaks | |
920 | * (min_count is set to 0). | |
921 | */ | |
922 | if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr)) | |
923 | for_each_possible_cpu(cpu) | |
924 | create_object((unsigned long)per_cpu_ptr(ptr, cpu), | |
925 | size, 0, GFP_KERNEL); | |
926 | else if (atomic_read(&kmemleak_early_log)) | |
927 | log_early(KMEMLEAK_ALLOC_PERCPU, ptr, size, 0); | |
928 | } | |
929 | EXPORT_SYMBOL_GPL(kmemleak_alloc_percpu); | |
930 | ||
931 | /** | |
932 | * kmemleak_free - unregister a previously registered object | |
933 | * @ptr: pointer to beginning of the object | |
934 | * | |
935 | * This function is called from the kernel allocators when an object (memory | |
936 | * block) is freed (kmem_cache_free, kfree, vfree etc.). | |
937 | */ | |
938 | void __ref kmemleak_free(const void *ptr) | |
939 | { | |
940 | pr_debug("%s(0x%p)\n", __func__, ptr); | |
941 | ||
942 | if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr)) | |
943 | delete_object_full((unsigned long)ptr); | |
944 | else if (atomic_read(&kmemleak_early_log)) | |
945 | log_early(KMEMLEAK_FREE, ptr, 0, 0); | |
946 | } | |
947 | EXPORT_SYMBOL_GPL(kmemleak_free); | |
948 | ||
949 | /** | |
950 | * kmemleak_free_part - partially unregister a previously registered object | |
951 | * @ptr: pointer to the beginning or inside the object. This also | |
952 | * represents the start of the range to be freed | |
953 | * @size: size to be unregistered | |
954 | * | |
955 | * This function is called when only a part of a memory block is freed | |
956 | * (usually from the bootmem allocator). | |
957 | */ | |
958 | void __ref kmemleak_free_part(const void *ptr, size_t size) | |
959 | { | |
960 | pr_debug("%s(0x%p)\n", __func__, ptr); | |
961 | ||
962 | if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr)) | |
963 | delete_object_part((unsigned long)ptr, size); | |
964 | else if (atomic_read(&kmemleak_early_log)) | |
965 | log_early(KMEMLEAK_FREE_PART, ptr, size, 0); | |
966 | } | |
967 | EXPORT_SYMBOL_GPL(kmemleak_free_part); | |
968 | ||
969 | /** | |
970 | * kmemleak_free_percpu - unregister a previously registered __percpu object | |
971 | * @ptr: __percpu pointer to beginning of the object | |
972 | * | |
973 | * This function is called from the kernel percpu allocator when an object | |
974 | * (memory block) is freed (free_percpu). | |
975 | */ | |
976 | void __ref kmemleak_free_percpu(const void __percpu *ptr) | |
977 | { | |
978 | unsigned int cpu; | |
979 | ||
980 | pr_debug("%s(0x%p)\n", __func__, ptr); | |
981 | ||
982 | if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr)) | |
983 | for_each_possible_cpu(cpu) | |
984 | delete_object_full((unsigned long)per_cpu_ptr(ptr, | |
985 | cpu)); | |
986 | else if (atomic_read(&kmemleak_early_log)) | |
987 | log_early(KMEMLEAK_FREE_PERCPU, ptr, 0, 0); | |
988 | } | |
989 | EXPORT_SYMBOL_GPL(kmemleak_free_percpu); | |
990 | ||
991 | /** | |
992 | * kmemleak_not_leak - mark an allocated object as false positive | |
993 | * @ptr: pointer to beginning of the object | |
994 | * | |
995 | * Calling this function on an object will cause the memory block to no longer | |
996 | * be reported as leak and always be scanned. | |
997 | */ | |
998 | void __ref kmemleak_not_leak(const void *ptr) | |
999 | { | |
1000 | pr_debug("%s(0x%p)\n", __func__, ptr); | |
1001 | ||
1002 | if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr)) | |
1003 | make_gray_object((unsigned long)ptr); | |
1004 | else if (atomic_read(&kmemleak_early_log)) | |
1005 | log_early(KMEMLEAK_NOT_LEAK, ptr, 0, 0); | |
1006 | } | |
1007 | EXPORT_SYMBOL(kmemleak_not_leak); | |
1008 | ||
1009 | /** | |
1010 | * kmemleak_ignore - ignore an allocated object | |
1011 | * @ptr: pointer to beginning of the object | |
1012 | * | |
1013 | * Calling this function on an object will cause the memory block to be | |
1014 | * ignored (not scanned and not reported as a leak). This is usually done when | |
1015 | * it is known that the corresponding block is not a leak and does not contain | |
1016 | * any references to other allocated memory blocks. | |
1017 | */ | |
1018 | void __ref kmemleak_ignore(const void *ptr) | |
1019 | { | |
1020 | pr_debug("%s(0x%p)\n", __func__, ptr); | |
1021 | ||
1022 | if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr)) | |
1023 | make_black_object((unsigned long)ptr); | |
1024 | else if (atomic_read(&kmemleak_early_log)) | |
1025 | log_early(KMEMLEAK_IGNORE, ptr, 0, 0); | |
1026 | } | |
1027 | EXPORT_SYMBOL(kmemleak_ignore); | |
1028 | ||
1029 | /** | |
1030 | * kmemleak_scan_area - limit the range to be scanned in an allocated object | |
1031 | * @ptr: pointer to beginning or inside the object. This also | |
1032 | * represents the start of the scan area | |
1033 | * @size: size of the scan area | |
1034 | * @gfp: kmalloc() flags used for kmemleak internal memory allocations | |
1035 | * | |
1036 | * This function is used when it is known that only certain parts of an object | |
1037 | * contain references to other objects. Kmemleak will only scan these areas | |
1038 | * reducing the number false negatives. | |
1039 | */ | |
1040 | void __ref kmemleak_scan_area(const void *ptr, size_t size, gfp_t gfp) | |
1041 | { | |
1042 | pr_debug("%s(0x%p)\n", __func__, ptr); | |
1043 | ||
1044 | if (atomic_read(&kmemleak_enabled) && ptr && size && !IS_ERR(ptr)) | |
1045 | add_scan_area((unsigned long)ptr, size, gfp); | |
1046 | else if (atomic_read(&kmemleak_early_log)) | |
1047 | log_early(KMEMLEAK_SCAN_AREA, ptr, size, 0); | |
1048 | } | |
1049 | EXPORT_SYMBOL(kmemleak_scan_area); | |
1050 | ||
1051 | /** | |
1052 | * kmemleak_no_scan - do not scan an allocated object | |
1053 | * @ptr: pointer to beginning of the object | |
1054 | * | |
1055 | * This function notifies kmemleak not to scan the given memory block. Useful | |
1056 | * in situations where it is known that the given object does not contain any | |
1057 | * references to other objects. Kmemleak will not scan such objects reducing | |
1058 | * the number of false negatives. | |
1059 | */ | |
1060 | void __ref kmemleak_no_scan(const void *ptr) | |
1061 | { | |
1062 | pr_debug("%s(0x%p)\n", __func__, ptr); | |
1063 | ||
1064 | if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr)) | |
1065 | object_no_scan((unsigned long)ptr); | |
1066 | else if (atomic_read(&kmemleak_early_log)) | |
1067 | log_early(KMEMLEAK_NO_SCAN, ptr, 0, 0); | |
1068 | } | |
1069 | EXPORT_SYMBOL(kmemleak_no_scan); | |
1070 | ||
1071 | /* | |
1072 | * Update an object's checksum and return true if it was modified. | |
1073 | */ | |
1074 | static bool update_checksum(struct kmemleak_object *object) | |
1075 | { | |
1076 | u32 old_csum = object->checksum; | |
1077 | ||
1078 | if (!kmemcheck_is_obj_initialized(object->pointer, object->size)) | |
1079 | return false; | |
1080 | ||
1081 | object->checksum = crc32(0, (void *)object->pointer, object->size); | |
1082 | return object->checksum != old_csum; | |
1083 | } | |
1084 | ||
1085 | /* | |
1086 | * Memory scanning is a long process and it needs to be interruptable. This | |
1087 | * function checks whether such interrupt condition occurred. | |
1088 | */ | |
1089 | static int scan_should_stop(void) | |
1090 | { | |
1091 | if (!atomic_read(&kmemleak_enabled)) | |
1092 | return 1; | |
1093 | ||
1094 | /* | |
1095 | * This function may be called from either process or kthread context, | |
1096 | * hence the need to check for both stop conditions. | |
1097 | */ | |
1098 | if (current->mm) | |
1099 | return signal_pending(current); | |
1100 | else | |
1101 | return kthread_should_stop(); | |
1102 | ||
1103 | return 0; | |
1104 | } | |
1105 | ||
1106 | /* | |
1107 | * Scan a memory block (exclusive range) for valid pointers and add those | |
1108 | * found to the gray list. | |
1109 | */ | |
1110 | static void scan_block(void *_start, void *_end, | |
1111 | struct kmemleak_object *scanned, int allow_resched) | |
1112 | { | |
1113 | unsigned long *ptr; | |
1114 | unsigned long *start = PTR_ALIGN(_start, BYTES_PER_POINTER); | |
1115 | unsigned long *end = _end - (BYTES_PER_POINTER - 1); | |
1116 | ||
1117 | for (ptr = start; ptr < end; ptr++) { | |
1118 | struct kmemleak_object *object; | |
1119 | unsigned long flags; | |
1120 | unsigned long pointer; | |
1121 | ||
1122 | if (allow_resched) | |
1123 | cond_resched(); | |
1124 | if (scan_should_stop()) | |
1125 | break; | |
1126 | ||
1127 | /* don't scan uninitialized memory */ | |
1128 | if (!kmemcheck_is_obj_initialized((unsigned long)ptr, | |
1129 | BYTES_PER_POINTER)) | |
1130 | continue; | |
1131 | ||
1132 | pointer = *ptr; | |
1133 | ||
1134 | object = find_and_get_object(pointer, 1); | |
1135 | if (!object) | |
1136 | continue; | |
1137 | if (object == scanned) { | |
1138 | /* self referenced, ignore */ | |
1139 | put_object(object); | |
1140 | continue; | |
1141 | } | |
1142 | ||
1143 | /* | |
1144 | * Avoid the lockdep recursive warning on object->lock being | |
1145 | * previously acquired in scan_object(). These locks are | |
1146 | * enclosed by scan_mutex. | |
1147 | */ | |
1148 | spin_lock_irqsave_nested(&object->lock, flags, | |
1149 | SINGLE_DEPTH_NESTING); | |
1150 | if (!color_white(object)) { | |
1151 | /* non-orphan, ignored or new */ | |
1152 | spin_unlock_irqrestore(&object->lock, flags); | |
1153 | put_object(object); | |
1154 | continue; | |
1155 | } | |
1156 | ||
1157 | /* | |
1158 | * Increase the object's reference count (number of pointers | |
1159 | * to the memory block). If this count reaches the required | |
1160 | * minimum, the object's color will become gray and it will be | |
1161 | * added to the gray_list. | |
1162 | */ | |
1163 | object->count++; | |
1164 | if (color_gray(object)) { | |
1165 | list_add_tail(&object->gray_list, &gray_list); | |
1166 | spin_unlock_irqrestore(&object->lock, flags); | |
1167 | continue; | |
1168 | } | |
1169 | ||
1170 | spin_unlock_irqrestore(&object->lock, flags); | |
1171 | put_object(object); | |
1172 | } | |
1173 | } | |
1174 | ||
1175 | /* | |
1176 | * Scan a memory block corresponding to a kmemleak_object. A condition is | |
1177 | * that object->use_count >= 1. | |
1178 | */ | |
1179 | static void scan_object(struct kmemleak_object *object) | |
1180 | { | |
1181 | struct kmemleak_scan_area *area; | |
1182 | unsigned long flags; | |
1183 | ||
1184 | /* | |
1185 | * Once the object->lock is acquired, the corresponding memory block | |
1186 | * cannot be freed (the same lock is acquired in delete_object). | |
1187 | */ | |
1188 | spin_lock_irqsave(&object->lock, flags); | |
1189 | if (object->flags & OBJECT_NO_SCAN) | |
1190 | goto out; | |
1191 | if (!(object->flags & OBJECT_ALLOCATED)) | |
1192 | /* already freed object */ | |
1193 | goto out; | |
1194 | if (hlist_empty(&object->area_list)) { | |
1195 | void *start = (void *)object->pointer; | |
1196 | void *end = (void *)(object->pointer + object->size); | |
1197 | ||
1198 | while (start < end && (object->flags & OBJECT_ALLOCATED) && | |
1199 | !(object->flags & OBJECT_NO_SCAN)) { | |
1200 | scan_block(start, min(start + MAX_SCAN_SIZE, end), | |
1201 | object, 0); | |
1202 | start += MAX_SCAN_SIZE; | |
1203 | ||
1204 | spin_unlock_irqrestore(&object->lock, flags); | |
1205 | cond_resched(); | |
1206 | spin_lock_irqsave(&object->lock, flags); | |
1207 | } | |
1208 | } else | |
1209 | hlist_for_each_entry(area, &object->area_list, node) | |
1210 | scan_block((void *)area->start, | |
1211 | (void *)(area->start + area->size), | |
1212 | object, 0); | |
1213 | out: | |
1214 | spin_unlock_irqrestore(&object->lock, flags); | |
1215 | } | |
1216 | ||
1217 | /* | |
1218 | * Scan the objects already referenced (gray objects). More objects will be | |
1219 | * referenced and, if there are no memory leaks, all the objects are scanned. | |
1220 | */ | |
1221 | static void scan_gray_list(void) | |
1222 | { | |
1223 | struct kmemleak_object *object, *tmp; | |
1224 | ||
1225 | /* | |
1226 | * The list traversal is safe for both tail additions and removals | |
1227 | * from inside the loop. The kmemleak objects cannot be freed from | |
1228 | * outside the loop because their use_count was incremented. | |
1229 | */ | |
1230 | object = list_entry(gray_list.next, typeof(*object), gray_list); | |
1231 | while (&object->gray_list != &gray_list) { | |
1232 | cond_resched(); | |
1233 | ||
1234 | /* may add new objects to the list */ | |
1235 | if (!scan_should_stop()) | |
1236 | scan_object(object); | |
1237 | ||
1238 | tmp = list_entry(object->gray_list.next, typeof(*object), | |
1239 | gray_list); | |
1240 | ||
1241 | /* remove the object from the list and release it */ | |
1242 | list_del(&object->gray_list); | |
1243 | put_object(object); | |
1244 | ||
1245 | object = tmp; | |
1246 | } | |
1247 | WARN_ON(!list_empty(&gray_list)); | |
1248 | } | |
1249 | ||
1250 | /* | |
1251 | * Scan data sections and all the referenced memory blocks allocated via the | |
1252 | * kernel's standard allocators. This function must be called with the | |
1253 | * scan_mutex held. | |
1254 | */ | |
1255 | static void kmemleak_scan(void) | |
1256 | { | |
1257 | unsigned long flags; | |
1258 | struct kmemleak_object *object; | |
1259 | int i; | |
1260 | int new_leaks = 0; | |
1261 | ||
1262 | jiffies_last_scan = jiffies; | |
1263 | ||
1264 | /* prepare the kmemleak_object's */ | |
1265 | rcu_read_lock(); | |
1266 | list_for_each_entry_rcu(object, &object_list, object_list) { | |
1267 | spin_lock_irqsave(&object->lock, flags); | |
1268 | #ifdef DEBUG | |
1269 | /* | |
1270 | * With a few exceptions there should be a maximum of | |
1271 | * 1 reference to any object at this point. | |
1272 | */ | |
1273 | if (atomic_read(&object->use_count) > 1) { | |
1274 | pr_debug("object->use_count = %d\n", | |
1275 | atomic_read(&object->use_count)); | |
1276 | dump_object_info(object); | |
1277 | } | |
1278 | #endif | |
1279 | /* reset the reference count (whiten the object) */ | |
1280 | object->count = 0; | |
1281 | if (color_gray(object) && get_object(object)) | |
1282 | list_add_tail(&object->gray_list, &gray_list); | |
1283 | ||
1284 | spin_unlock_irqrestore(&object->lock, flags); | |
1285 | } | |
1286 | rcu_read_unlock(); | |
1287 | ||
1288 | /* data/bss scanning */ | |
1289 | scan_block(_sdata, _edata, NULL, 1); | |
1290 | scan_block(__bss_start, __bss_stop, NULL, 1); | |
1291 | ||
1292 | #ifdef CONFIG_SMP | |
1293 | /* per-cpu sections scanning */ | |
1294 | for_each_possible_cpu(i) | |
1295 | scan_block(__per_cpu_start + per_cpu_offset(i), | |
1296 | __per_cpu_end + per_cpu_offset(i), NULL, 1); | |
1297 | #endif | |
1298 | ||
1299 | /* | |
1300 | * Struct page scanning for each node. | |
1301 | */ | |
1302 | lock_memory_hotplug(); | |
1303 | for_each_online_node(i) { | |
1304 | unsigned long start_pfn = node_start_pfn(i); | |
1305 | unsigned long end_pfn = node_end_pfn(i); | |
1306 | unsigned long pfn; | |
1307 | ||
1308 | for (pfn = start_pfn; pfn < end_pfn; pfn++) { | |
1309 | struct page *page; | |
1310 | ||
1311 | if (!pfn_valid(pfn)) | |
1312 | continue; | |
1313 | page = pfn_to_page(pfn); | |
1314 | /* only scan if page is in use */ | |
1315 | if (page_count(page) == 0) | |
1316 | continue; | |
1317 | scan_block(page, page + 1, NULL, 1); | |
1318 | } | |
1319 | } | |
1320 | unlock_memory_hotplug(); | |
1321 | ||
1322 | /* | |
1323 | * Scanning the task stacks (may introduce false negatives). | |
1324 | */ | |
1325 | if (kmemleak_stack_scan) { | |
1326 | struct task_struct *p, *g; | |
1327 | ||
1328 | read_lock(&tasklist_lock); | |
1329 | do_each_thread(g, p) { | |
1330 | scan_block(task_stack_page(p), task_stack_page(p) + | |
1331 | THREAD_SIZE, NULL, 0); | |
1332 | } while_each_thread(g, p); | |
1333 | read_unlock(&tasklist_lock); | |
1334 | } | |
1335 | ||
1336 | /* | |
1337 | * Scan the objects already referenced from the sections scanned | |
1338 | * above. | |
1339 | */ | |
1340 | scan_gray_list(); | |
1341 | ||
1342 | /* | |
1343 | * Check for new or unreferenced objects modified since the previous | |
1344 | * scan and color them gray until the next scan. | |
1345 | */ | |
1346 | rcu_read_lock(); | |
1347 | list_for_each_entry_rcu(object, &object_list, object_list) { | |
1348 | spin_lock_irqsave(&object->lock, flags); | |
1349 | if (color_white(object) && (object->flags & OBJECT_ALLOCATED) | |
1350 | && update_checksum(object) && get_object(object)) { | |
1351 | /* color it gray temporarily */ | |
1352 | object->count = object->min_count; | |
1353 | list_add_tail(&object->gray_list, &gray_list); | |
1354 | } | |
1355 | spin_unlock_irqrestore(&object->lock, flags); | |
1356 | } | |
1357 | rcu_read_unlock(); | |
1358 | ||
1359 | /* | |
1360 | * Re-scan the gray list for modified unreferenced objects. | |
1361 | */ | |
1362 | scan_gray_list(); | |
1363 | ||
1364 | /* | |
1365 | * If scanning was stopped do not report any new unreferenced objects. | |
1366 | */ | |
1367 | if (scan_should_stop()) | |
1368 | return; | |
1369 | ||
1370 | /* | |
1371 | * Scanning result reporting. | |
1372 | */ | |
1373 | rcu_read_lock(); | |
1374 | list_for_each_entry_rcu(object, &object_list, object_list) { | |
1375 | spin_lock_irqsave(&object->lock, flags); | |
1376 | if (unreferenced_object(object) && | |
1377 | !(object->flags & OBJECT_REPORTED)) { | |
1378 | object->flags |= OBJECT_REPORTED; | |
1379 | new_leaks++; | |
1380 | } | |
1381 | spin_unlock_irqrestore(&object->lock, flags); | |
1382 | } | |
1383 | rcu_read_unlock(); | |
1384 | ||
1385 | if (new_leaks) | |
1386 | pr_info("%d new suspected memory leaks (see " | |
1387 | "/sys/kernel/debug/kmemleak)\n", new_leaks); | |
1388 | ||
1389 | } | |
1390 | ||
1391 | /* | |
1392 | * Thread function performing automatic memory scanning. Unreferenced objects | |
1393 | * at the end of a memory scan are reported but only the first time. | |
1394 | */ | |
1395 | static int kmemleak_scan_thread(void *arg) | |
1396 | { | |
1397 | static int first_run = 1; | |
1398 | ||
1399 | pr_info("Automatic memory scanning thread started\n"); | |
1400 | set_user_nice(current, 10); | |
1401 | ||
1402 | /* | |
1403 | * Wait before the first scan to allow the system to fully initialize. | |
1404 | */ | |
1405 | if (first_run) { | |
1406 | first_run = 0; | |
1407 | ssleep(SECS_FIRST_SCAN); | |
1408 | } | |
1409 | ||
1410 | while (!kthread_should_stop()) { | |
1411 | signed long timeout = jiffies_scan_wait; | |
1412 | ||
1413 | mutex_lock(&scan_mutex); | |
1414 | kmemleak_scan(); | |
1415 | mutex_unlock(&scan_mutex); | |
1416 | ||
1417 | /* wait before the next scan */ | |
1418 | while (timeout && !kthread_should_stop()) | |
1419 | timeout = schedule_timeout_interruptible(timeout); | |
1420 | } | |
1421 | ||
1422 | pr_info("Automatic memory scanning thread ended\n"); | |
1423 | ||
1424 | return 0; | |
1425 | } | |
1426 | ||
1427 | /* | |
1428 | * Start the automatic memory scanning thread. This function must be called | |
1429 | * with the scan_mutex held. | |
1430 | */ | |
1431 | static void start_scan_thread(void) | |
1432 | { | |
1433 | if (scan_thread) | |
1434 | return; | |
1435 | scan_thread = kthread_run(kmemleak_scan_thread, NULL, "kmemleak"); | |
1436 | if (IS_ERR(scan_thread)) { | |
1437 | pr_warning("Failed to create the scan thread\n"); | |
1438 | scan_thread = NULL; | |
1439 | } | |
1440 | } | |
1441 | ||
1442 | /* | |
1443 | * Stop the automatic memory scanning thread. This function must be called | |
1444 | * with the scan_mutex held. | |
1445 | */ | |
1446 | static void stop_scan_thread(void) | |
1447 | { | |
1448 | if (scan_thread) { | |
1449 | kthread_stop(scan_thread); | |
1450 | scan_thread = NULL; | |
1451 | } | |
1452 | } | |
1453 | ||
1454 | /* | |
1455 | * Iterate over the object_list and return the first valid object at or after | |
1456 | * the required position with its use_count incremented. The function triggers | |
1457 | * a memory scanning when the pos argument points to the first position. | |
1458 | */ | |
1459 | static void *kmemleak_seq_start(struct seq_file *seq, loff_t *pos) | |
1460 | { | |
1461 | struct kmemleak_object *object; | |
1462 | loff_t n = *pos; | |
1463 | int err; | |
1464 | ||
1465 | err = mutex_lock_interruptible(&scan_mutex); | |
1466 | if (err < 0) | |
1467 | return ERR_PTR(err); | |
1468 | ||
1469 | rcu_read_lock(); | |
1470 | list_for_each_entry_rcu(object, &object_list, object_list) { | |
1471 | if (n-- > 0) | |
1472 | continue; | |
1473 | if (get_object(object)) | |
1474 | goto out; | |
1475 | } | |
1476 | object = NULL; | |
1477 | out: | |
1478 | return object; | |
1479 | } | |
1480 | ||
1481 | /* | |
1482 | * Return the next object in the object_list. The function decrements the | |
1483 | * use_count of the previous object and increases that of the next one. | |
1484 | */ | |
1485 | static void *kmemleak_seq_next(struct seq_file *seq, void *v, loff_t *pos) | |
1486 | { | |
1487 | struct kmemleak_object *prev_obj = v; | |
1488 | struct kmemleak_object *next_obj = NULL; | |
1489 | struct kmemleak_object *obj = prev_obj; | |
1490 | ||
1491 | ++(*pos); | |
1492 | ||
1493 | list_for_each_entry_continue_rcu(obj, &object_list, object_list) { | |
1494 | if (get_object(obj)) { | |
1495 | next_obj = obj; | |
1496 | break; | |
1497 | } | |
1498 | } | |
1499 | ||
1500 | put_object(prev_obj); | |
1501 | return next_obj; | |
1502 | } | |
1503 | ||
1504 | /* | |
1505 | * Decrement the use_count of the last object required, if any. | |
1506 | */ | |
1507 | static void kmemleak_seq_stop(struct seq_file *seq, void *v) | |
1508 | { | |
1509 | if (!IS_ERR(v)) { | |
1510 | /* | |
1511 | * kmemleak_seq_start may return ERR_PTR if the scan_mutex | |
1512 | * waiting was interrupted, so only release it if !IS_ERR. | |
1513 | */ | |
1514 | rcu_read_unlock(); | |
1515 | mutex_unlock(&scan_mutex); | |
1516 | if (v) | |
1517 | put_object(v); | |
1518 | } | |
1519 | } | |
1520 | ||
1521 | /* | |
1522 | * Print the information for an unreferenced object to the seq file. | |
1523 | */ | |
1524 | static int kmemleak_seq_show(struct seq_file *seq, void *v) | |
1525 | { | |
1526 | struct kmemleak_object *object = v; | |
1527 | unsigned long flags; | |
1528 | ||
1529 | spin_lock_irqsave(&object->lock, flags); | |
1530 | if ((object->flags & OBJECT_REPORTED) && unreferenced_object(object)) | |
1531 | print_unreferenced(seq, object); | |
1532 | spin_unlock_irqrestore(&object->lock, flags); | |
1533 | return 0; | |
1534 | } | |
1535 | ||
1536 | static const struct seq_operations kmemleak_seq_ops = { | |
1537 | .start = kmemleak_seq_start, | |
1538 | .next = kmemleak_seq_next, | |
1539 | .stop = kmemleak_seq_stop, | |
1540 | .show = kmemleak_seq_show, | |
1541 | }; | |
1542 | ||
1543 | static int kmemleak_open(struct inode *inode, struct file *file) | |
1544 | { | |
1545 | return seq_open(file, &kmemleak_seq_ops); | |
1546 | } | |
1547 | ||
1548 | static int kmemleak_release(struct inode *inode, struct file *file) | |
1549 | { | |
1550 | return seq_release(inode, file); | |
1551 | } | |
1552 | ||
1553 | static int dump_str_object_info(const char *str) | |
1554 | { | |
1555 | unsigned long flags; | |
1556 | struct kmemleak_object *object; | |
1557 | unsigned long addr; | |
1558 | ||
1559 | if (kstrtoul(str, 0, &addr)) | |
1560 | return -EINVAL; | |
1561 | object = find_and_get_object(addr, 0); | |
1562 | if (!object) { | |
1563 | pr_info("Unknown object at 0x%08lx\n", addr); | |
1564 | return -EINVAL; | |
1565 | } | |
1566 | ||
1567 | spin_lock_irqsave(&object->lock, flags); | |
1568 | dump_object_info(object); | |
1569 | spin_unlock_irqrestore(&object->lock, flags); | |
1570 | ||
1571 | put_object(object); | |
1572 | return 0; | |
1573 | } | |
1574 | ||
1575 | /* | |
1576 | * We use grey instead of black to ensure we can do future scans on the same | |
1577 | * objects. If we did not do future scans these black objects could | |
1578 | * potentially contain references to newly allocated objects in the future and | |
1579 | * we'd end up with false positives. | |
1580 | */ | |
1581 | static void kmemleak_clear(void) | |
1582 | { | |
1583 | struct kmemleak_object *object; | |
1584 | unsigned long flags; | |
1585 | ||
1586 | rcu_read_lock(); | |
1587 | list_for_each_entry_rcu(object, &object_list, object_list) { | |
1588 | spin_lock_irqsave(&object->lock, flags); | |
1589 | if ((object->flags & OBJECT_REPORTED) && | |
1590 | unreferenced_object(object)) | |
1591 | __paint_it(object, KMEMLEAK_GREY); | |
1592 | spin_unlock_irqrestore(&object->lock, flags); | |
1593 | } | |
1594 | rcu_read_unlock(); | |
1595 | } | |
1596 | ||
1597 | /* | |
1598 | * File write operation to configure kmemleak at run-time. The following | |
1599 | * commands can be written to the /sys/kernel/debug/kmemleak file: | |
1600 | * off - disable kmemleak (irreversible) | |
1601 | * stack=on - enable the task stacks scanning | |
1602 | * stack=off - disable the tasks stacks scanning | |
1603 | * scan=on - start the automatic memory scanning thread | |
1604 | * scan=off - stop the automatic memory scanning thread | |
1605 | * scan=... - set the automatic memory scanning period in seconds (0 to | |
1606 | * disable it) | |
1607 | * scan - trigger a memory scan | |
1608 | * clear - mark all current reported unreferenced kmemleak objects as | |
1609 | * grey to ignore printing them | |
1610 | * dump=... - dump information about the object found at the given address | |
1611 | */ | |
1612 | static ssize_t kmemleak_write(struct file *file, const char __user *user_buf, | |
1613 | size_t size, loff_t *ppos) | |
1614 | { | |
1615 | char buf[64]; | |
1616 | int buf_size; | |
1617 | int ret; | |
1618 | ||
1619 | if (!atomic_read(&kmemleak_enabled)) | |
1620 | return -EBUSY; | |
1621 | ||
1622 | buf_size = min(size, (sizeof(buf) - 1)); | |
1623 | if (strncpy_from_user(buf, user_buf, buf_size) < 0) | |
1624 | return -EFAULT; | |
1625 | buf[buf_size] = 0; | |
1626 | ||
1627 | ret = mutex_lock_interruptible(&scan_mutex); | |
1628 | if (ret < 0) | |
1629 | return ret; | |
1630 | ||
1631 | if (strncmp(buf, "off", 3) == 0) | |
1632 | kmemleak_disable(); | |
1633 | else if (strncmp(buf, "stack=on", 8) == 0) | |
1634 | kmemleak_stack_scan = 1; | |
1635 | else if (strncmp(buf, "stack=off", 9) == 0) | |
1636 | kmemleak_stack_scan = 0; | |
1637 | else if (strncmp(buf, "scan=on", 7) == 0) | |
1638 | start_scan_thread(); | |
1639 | else if (strncmp(buf, "scan=off", 8) == 0) | |
1640 | stop_scan_thread(); | |
1641 | else if (strncmp(buf, "scan=", 5) == 0) { | |
1642 | unsigned long secs; | |
1643 | ||
1644 | ret = kstrtoul(buf + 5, 0, &secs); | |
1645 | if (ret < 0) | |
1646 | goto out; | |
1647 | stop_scan_thread(); | |
1648 | if (secs) { | |
1649 | jiffies_scan_wait = msecs_to_jiffies(secs * 1000); | |
1650 | start_scan_thread(); | |
1651 | } | |
1652 | } else if (strncmp(buf, "scan", 4) == 0) | |
1653 | kmemleak_scan(); | |
1654 | else if (strncmp(buf, "clear", 5) == 0) | |
1655 | kmemleak_clear(); | |
1656 | else if (strncmp(buf, "dump=", 5) == 0) | |
1657 | ret = dump_str_object_info(buf + 5); | |
1658 | else | |
1659 | ret = -EINVAL; | |
1660 | ||
1661 | out: | |
1662 | mutex_unlock(&scan_mutex); | |
1663 | if (ret < 0) | |
1664 | return ret; | |
1665 | ||
1666 | /* ignore the rest of the buffer, only one command at a time */ | |
1667 | *ppos += size; | |
1668 | return size; | |
1669 | } | |
1670 | ||
1671 | static const struct file_operations kmemleak_fops = { | |
1672 | .owner = THIS_MODULE, | |
1673 | .open = kmemleak_open, | |
1674 | .read = seq_read, | |
1675 | .write = kmemleak_write, | |
1676 | .llseek = seq_lseek, | |
1677 | .release = kmemleak_release, | |
1678 | }; | |
1679 | ||
1680 | /* | |
1681 | * Stop the memory scanning thread and free the kmemleak internal objects if | |
1682 | * no previous scan thread (otherwise, kmemleak may still have some useful | |
1683 | * information on memory leaks). | |
1684 | */ | |
1685 | static void kmemleak_do_cleanup(struct work_struct *work) | |
1686 | { | |
1687 | struct kmemleak_object *object; | |
1688 | bool cleanup = scan_thread == NULL; | |
1689 | ||
1690 | mutex_lock(&scan_mutex); | |
1691 | stop_scan_thread(); | |
1692 | ||
1693 | if (cleanup) { | |
1694 | rcu_read_lock(); | |
1695 | list_for_each_entry_rcu(object, &object_list, object_list) | |
1696 | delete_object_full(object->pointer); | |
1697 | rcu_read_unlock(); | |
1698 | } | |
1699 | mutex_unlock(&scan_mutex); | |
1700 | } | |
1701 | ||
1702 | static DECLARE_WORK(cleanup_work, kmemleak_do_cleanup); | |
1703 | ||
1704 | /* | |
1705 | * Disable kmemleak. No memory allocation/freeing will be traced once this | |
1706 | * function is called. Disabling kmemleak is an irreversible operation. | |
1707 | */ | |
1708 | static void kmemleak_disable(void) | |
1709 | { | |
1710 | /* atomically check whether it was already invoked */ | |
1711 | if (atomic_cmpxchg(&kmemleak_error, 0, 1)) | |
1712 | return; | |
1713 | ||
1714 | /* stop any memory operation tracing */ | |
1715 | atomic_set(&kmemleak_enabled, 0); | |
1716 | ||
1717 | /* check whether it is too early for a kernel thread */ | |
1718 | if (atomic_read(&kmemleak_initialized)) | |
1719 | schedule_work(&cleanup_work); | |
1720 | ||
1721 | pr_info("Kernel memory leak detector disabled\n"); | |
1722 | } | |
1723 | ||
1724 | /* | |
1725 | * Allow boot-time kmemleak disabling (enabled by default). | |
1726 | */ | |
1727 | static int kmemleak_boot_config(char *str) | |
1728 | { | |
1729 | if (!str) | |
1730 | return -EINVAL; | |
1731 | if (strcmp(str, "off") == 0) | |
1732 | kmemleak_disable(); | |
1733 | else if (strcmp(str, "on") == 0) | |
1734 | kmemleak_skip_disable = 1; | |
1735 | else | |
1736 | return -EINVAL; | |
1737 | return 0; | |
1738 | } | |
1739 | early_param("kmemleak", kmemleak_boot_config); | |
1740 | ||
1741 | static void __init print_log_trace(struct early_log *log) | |
1742 | { | |
1743 | struct stack_trace trace; | |
1744 | ||
1745 | trace.nr_entries = log->trace_len; | |
1746 | trace.entries = log->trace; | |
1747 | ||
1748 | pr_notice("Early log backtrace:\n"); | |
1749 | print_stack_trace(&trace, 2); | |
1750 | } | |
1751 | ||
1752 | /* | |
1753 | * Kmemleak initialization. | |
1754 | */ | |
1755 | void __init kmemleak_init(void) | |
1756 | { | |
1757 | int i; | |
1758 | unsigned long flags; | |
1759 | ||
1760 | #ifdef CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF | |
1761 | if (!kmemleak_skip_disable) { | |
1762 | atomic_set(&kmemleak_early_log, 0); | |
1763 | kmemleak_disable(); | |
1764 | return; | |
1765 | } | |
1766 | #endif | |
1767 | ||
1768 | jiffies_min_age = msecs_to_jiffies(MSECS_MIN_AGE); | |
1769 | jiffies_scan_wait = msecs_to_jiffies(SECS_SCAN_WAIT * 1000); | |
1770 | ||
1771 | object_cache = KMEM_CACHE(kmemleak_object, SLAB_NOLEAKTRACE); | |
1772 | scan_area_cache = KMEM_CACHE(kmemleak_scan_area, SLAB_NOLEAKTRACE); | |
1773 | ||
1774 | if (crt_early_log >= ARRAY_SIZE(early_log)) | |
1775 | pr_warning("Early log buffer exceeded (%d), please increase " | |
1776 | "DEBUG_KMEMLEAK_EARLY_LOG_SIZE\n", crt_early_log); | |
1777 | ||
1778 | /* the kernel is still in UP mode, so disabling the IRQs is enough */ | |
1779 | local_irq_save(flags); | |
1780 | atomic_set(&kmemleak_early_log, 0); | |
1781 | if (atomic_read(&kmemleak_error)) { | |
1782 | local_irq_restore(flags); | |
1783 | return; | |
1784 | } else | |
1785 | atomic_set(&kmemleak_enabled, 1); | |
1786 | local_irq_restore(flags); | |
1787 | ||
1788 | /* | |
1789 | * This is the point where tracking allocations is safe. Automatic | |
1790 | * scanning is started during the late initcall. Add the early logged | |
1791 | * callbacks to the kmemleak infrastructure. | |
1792 | */ | |
1793 | for (i = 0; i < crt_early_log; i++) { | |
1794 | struct early_log *log = &early_log[i]; | |
1795 | ||
1796 | switch (log->op_type) { | |
1797 | case KMEMLEAK_ALLOC: | |
1798 | early_alloc(log); | |
1799 | break; | |
1800 | case KMEMLEAK_ALLOC_PERCPU: | |
1801 | early_alloc_percpu(log); | |
1802 | break; | |
1803 | case KMEMLEAK_FREE: | |
1804 | kmemleak_free(log->ptr); | |
1805 | break; | |
1806 | case KMEMLEAK_FREE_PART: | |
1807 | kmemleak_free_part(log->ptr, log->size); | |
1808 | break; | |
1809 | case KMEMLEAK_FREE_PERCPU: | |
1810 | kmemleak_free_percpu(log->ptr); | |
1811 | break; | |
1812 | case KMEMLEAK_NOT_LEAK: | |
1813 | kmemleak_not_leak(log->ptr); | |
1814 | break; | |
1815 | case KMEMLEAK_IGNORE: | |
1816 | kmemleak_ignore(log->ptr); | |
1817 | break; | |
1818 | case KMEMLEAK_SCAN_AREA: | |
1819 | kmemleak_scan_area(log->ptr, log->size, GFP_KERNEL); | |
1820 | break; | |
1821 | case KMEMLEAK_NO_SCAN: | |
1822 | kmemleak_no_scan(log->ptr); | |
1823 | break; | |
1824 | default: | |
1825 | kmemleak_warn("Unknown early log operation: %d\n", | |
1826 | log->op_type); | |
1827 | } | |
1828 | ||
1829 | if (atomic_read(&kmemleak_warning)) { | |
1830 | print_log_trace(log); | |
1831 | atomic_set(&kmemleak_warning, 0); | |
1832 | } | |
1833 | } | |
1834 | } | |
1835 | ||
1836 | /* | |
1837 | * Late initialization function. | |
1838 | */ | |
1839 | static int __init kmemleak_late_init(void) | |
1840 | { | |
1841 | struct dentry *dentry; | |
1842 | ||
1843 | atomic_set(&kmemleak_initialized, 1); | |
1844 | ||
1845 | if (atomic_read(&kmemleak_error)) { | |
1846 | /* | |
1847 | * Some error occurred and kmemleak was disabled. There is a | |
1848 | * small chance that kmemleak_disable() was called immediately | |
1849 | * after setting kmemleak_initialized and we may end up with | |
1850 | * two clean-up threads but serialized by scan_mutex. | |
1851 | */ | |
1852 | schedule_work(&cleanup_work); | |
1853 | return -ENOMEM; | |
1854 | } | |
1855 | ||
1856 | dentry = debugfs_create_file("kmemleak", S_IRUGO, NULL, NULL, | |
1857 | &kmemleak_fops); | |
1858 | if (!dentry) | |
1859 | pr_warning("Failed to create the debugfs kmemleak file\n"); | |
1860 | mutex_lock(&scan_mutex); | |
1861 | start_scan_thread(); | |
1862 | mutex_unlock(&scan_mutex); | |
1863 | ||
1864 | pr_info("Kernel memory leak detector initialized\n"); | |
1865 | ||
1866 | return 0; | |
1867 | } | |
1868 | late_initcall(kmemleak_late_init); |