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Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001/*
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 priority search 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
Catalin Marinas4698c1f2009-06-26 17:38:27 +010051 * 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
Catalin Marinas3c7b4e62009-06-11 13:22:39 +010055 *
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
Joe Perchesae281062009-06-23 14:40:26 +010064#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
65
Catalin Marinas3c7b4e62009-06-11 13:22:39 +010066#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/module.h>
73#include <linux/kthread.h>
74#include <linux/prio_tree.h>
Catalin Marinas3c7b4e62009-06-11 13:22:39 +010075#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>
Catalin Marinas179a8102009-09-07 10:14:42 +010094#include <linux/workqueue.h>
Catalin Marinas04609ccc2009-10-28 13:33:12 +000095#include <linux/crc32.h>
Catalin Marinas3c7b4e62009-06-11 13:22:39 +010096
97#include <asm/sections.h>
98#include <asm/processor.h>
99#include <asm/atomic.h>
100
Pekka Enberg8e019362009-08-27 14:50:00 +0100101#include <linux/kmemcheck.h>
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100102#include <linux/kmemleak.h>
103
104/*
105 * Kmemleak configuration and common defines.
106 */
107#define MAX_TRACE 16 /* stack trace length */
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100108#define MSECS_MIN_AGE 5000 /* minimum object age for reporting */
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100109#define SECS_FIRST_SCAN 60 /* delay before the first scan */
110#define SECS_SCAN_WAIT 600 /* subsequent auto scanning delay */
Catalin Marinasaf986032009-08-27 14:29:12 +0100111#define MAX_SCAN_SIZE 4096 /* maximum size of a scanned block */
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100112
113#define BYTES_PER_POINTER sizeof(void *)
114
Catalin Marinas216c04b2009-06-17 18:29:02 +0100115/* GFP bitmask for kmemleak internal allocations */
Catalin Marinas6ae4bd12011-01-27 10:30:26 +0000116#define gfp_kmemleak_mask(gfp) (((gfp) & (GFP_KERNEL | GFP_ATOMIC)) | \
117 __GFP_NORETRY | __GFP_NOMEMALLOC | \
118 __GFP_NOWARN)
Catalin Marinas216c04b2009-06-17 18:29:02 +0100119
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100120/* scanning area inside a memory block */
121struct kmemleak_scan_area {
122 struct hlist_node node;
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000123 unsigned long start;
124 size_t size;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100125};
126
Luis R. Rodrigueza1084c82009-09-04 17:44:52 -0700127#define KMEMLEAK_GREY 0
128#define KMEMLEAK_BLACK -1
129
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100130/*
131 * Structure holding the metadata for each allocated memory block.
132 * Modifications to such objects should be made while holding the
133 * object->lock. Insertions or deletions from object_list, gray_list or
134 * tree_node are already protected by the corresponding locks or mutex (see
135 * the notes on locking above). These objects are reference-counted
136 * (use_count) and freed using the RCU mechanism.
137 */
138struct kmemleak_object {
139 spinlock_t lock;
140 unsigned long flags; /* object status flags */
141 struct list_head object_list;
142 struct list_head gray_list;
143 struct prio_tree_node tree_node;
144 struct rcu_head rcu; /* object_list lockless traversal */
145 /* object usage count; object freed when use_count == 0 */
146 atomic_t use_count;
147 unsigned long pointer;
148 size_t size;
149 /* minimum number of a pointers found before it is considered leak */
150 int min_count;
151 /* the total number of pointers found pointing to this object */
152 int count;
Catalin Marinas04609ccc2009-10-28 13:33:12 +0000153 /* checksum for detecting modified objects */
154 u32 checksum;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100155 /* memory ranges to be scanned inside an object (empty for all) */
156 struct hlist_head area_list;
157 unsigned long trace[MAX_TRACE];
158 unsigned int trace_len;
159 unsigned long jiffies; /* creation timestamp */
160 pid_t pid; /* pid of the current task */
161 char comm[TASK_COMM_LEN]; /* executable name */
162};
163
164/* flag representing the memory block allocation status */
165#define OBJECT_ALLOCATED (1 << 0)
166/* flag set after the first reporting of an unreference object */
167#define OBJECT_REPORTED (1 << 1)
168/* flag set to not scan the object */
169#define OBJECT_NO_SCAN (1 << 2)
170
Sergey Senozhatsky0494e082009-08-27 14:29:18 +0100171/* number of bytes to print per line; must be 16 or 32 */
172#define HEX_ROW_SIZE 16
173/* number of bytes to print at a time (1, 2, 4, 8) */
174#define HEX_GROUP_SIZE 1
175/* include ASCII after the hex output */
176#define HEX_ASCII 1
177/* max number of lines to be printed */
178#define HEX_MAX_LINES 2
179
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100180/* the list of all allocated objects */
181static LIST_HEAD(object_list);
182/* the list of gray-colored objects (see color_gray comment below) */
183static LIST_HEAD(gray_list);
184/* prio search tree for object boundaries */
185static struct prio_tree_root object_tree_root;
186/* rw_lock protecting the access to object_list and prio_tree_root */
187static DEFINE_RWLOCK(kmemleak_lock);
188
189/* allocation caches for kmemleak internal data */
190static struct kmem_cache *object_cache;
191static struct kmem_cache *scan_area_cache;
192
193/* set if tracing memory operations is enabled */
194static atomic_t kmemleak_enabled = ATOMIC_INIT(0);
195/* set in the late_initcall if there were no errors */
196static atomic_t kmemleak_initialized = ATOMIC_INIT(0);
197/* enables or disables early logging of the memory operations */
198static atomic_t kmemleak_early_log = ATOMIC_INIT(1);
199/* set if a fata kmemleak error has occurred */
200static atomic_t kmemleak_error = ATOMIC_INIT(0);
201
202/* minimum and maximum address that may be valid pointers */
203static unsigned long min_addr = ULONG_MAX;
204static unsigned long max_addr;
205
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100206static struct task_struct *scan_thread;
Catalin Marinasacf49682009-06-26 17:38:29 +0100207/* used to avoid reporting of recently allocated objects */
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100208static unsigned long jiffies_min_age;
Catalin Marinasacf49682009-06-26 17:38:29 +0100209static unsigned long jiffies_last_scan;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100210/* delay between automatic memory scannings */
211static signed long jiffies_scan_wait;
212/* enables or disables the task stacks scanning */
Catalin Marinase0a2a162009-06-26 17:38:25 +0100213static int kmemleak_stack_scan = 1;
Catalin Marinas4698c1f2009-06-26 17:38:27 +0100214/* protects the memory scanning, parameters and debug/kmemleak file access */
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100215static DEFINE_MUTEX(scan_mutex);
Jason Baronab0155a2010-07-19 11:54:17 +0100216/* setting kmemleak=on, will set this var, skipping the disable */
217static int kmemleak_skip_disable;
218
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100219
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100220/*
Catalin Marinas20301172009-06-17 18:29:04 +0100221 * Early object allocation/freeing logging. Kmemleak is initialized after the
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100222 * kernel allocator. However, both the kernel allocator and kmemleak may
Catalin Marinas20301172009-06-17 18:29:04 +0100223 * allocate memory blocks which need to be tracked. Kmemleak defines an
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100224 * arbitrary buffer to hold the allocation/freeing information before it is
225 * fully initialized.
226 */
227
228/* kmemleak operation type for early logging */
229enum {
230 KMEMLEAK_ALLOC,
231 KMEMLEAK_FREE,
Catalin Marinas53238a62009-07-07 10:33:00 +0100232 KMEMLEAK_FREE_PART,
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100233 KMEMLEAK_NOT_LEAK,
234 KMEMLEAK_IGNORE,
235 KMEMLEAK_SCAN_AREA,
236 KMEMLEAK_NO_SCAN
237};
238
239/*
240 * Structure holding the information passed to kmemleak callbacks during the
241 * early logging.
242 */
243struct early_log {
244 int op_type; /* kmemleak operation type */
245 const void *ptr; /* allocated/freed memory block */
246 size_t size; /* memory block size */
247 int min_count; /* minimum reference count */
Catalin Marinasfd678962009-08-27 14:29:17 +0100248 unsigned long trace[MAX_TRACE]; /* stack trace */
249 unsigned int trace_len; /* stack trace length */
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100250};
251
252/* early logging buffer and current position */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100253static struct early_log
254 early_log[CONFIG_DEBUG_KMEMLEAK_EARLY_LOG_SIZE] __initdata;
255static int crt_early_log __initdata;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100256
257static void kmemleak_disable(void);
258
259/*
260 * Print a warning and dump the stack trace.
261 */
262#define kmemleak_warn(x...) do { \
263 pr_warning(x); \
264 dump_stack(); \
265} while (0)
266
267/*
Lucas De Marchi25985ed2011-03-30 22:57:33 -0300268 * Macro invoked when a serious kmemleak condition occurred and cannot be
Catalin Marinas20301172009-06-17 18:29:04 +0100269 * recovered from. Kmemleak will be disabled and further allocation/freeing
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100270 * tracing no longer available.
271 */
Catalin Marinas000814f2009-06-17 18:29:03 +0100272#define kmemleak_stop(x...) do { \
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100273 kmemleak_warn(x); \
274 kmemleak_disable(); \
275} while (0)
276
277/*
Sergey Senozhatsky0494e082009-08-27 14:29:18 +0100278 * Printing of the objects hex dump to the seq file. The number of lines to be
279 * printed is limited to HEX_MAX_LINES to prevent seq file spamming. The
280 * actual number of printed bytes depends on HEX_ROW_SIZE. It must be called
281 * with the object->lock held.
282 */
283static void hex_dump_object(struct seq_file *seq,
284 struct kmemleak_object *object)
285{
286 const u8 *ptr = (const u8 *)object->pointer;
287 int i, len, remaining;
288 unsigned char linebuf[HEX_ROW_SIZE * 5];
289
290 /* limit the number of lines to HEX_MAX_LINES */
291 remaining = len =
292 min(object->size, (size_t)(HEX_MAX_LINES * HEX_ROW_SIZE));
293
294 seq_printf(seq, " hex dump (first %d bytes):\n", len);
295 for (i = 0; i < len; i += HEX_ROW_SIZE) {
296 int linelen = min(remaining, HEX_ROW_SIZE);
297
298 remaining -= HEX_ROW_SIZE;
299 hex_dump_to_buffer(ptr + i, linelen, HEX_ROW_SIZE,
300 HEX_GROUP_SIZE, linebuf, sizeof(linebuf),
301 HEX_ASCII);
302 seq_printf(seq, " %s\n", linebuf);
303 }
304}
305
306/*
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100307 * Object colors, encoded with count and min_count:
308 * - white - orphan object, not enough references to it (count < min_count)
309 * - gray - not orphan, not marked as false positive (min_count == 0) or
310 * sufficient references to it (count >= min_count)
311 * - black - ignore, it doesn't contain references (e.g. text section)
312 * (min_count == -1). No function defined for this color.
313 * Newly created objects don't have any color assigned (object->count == -1)
314 * before the next memory scan when they become white.
315 */
Luis R. Rodriguez4a558dd2009-09-08 16:34:50 +0100316static bool color_white(const struct kmemleak_object *object)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100317{
Luis R. Rodrigueza1084c82009-09-04 17:44:52 -0700318 return object->count != KMEMLEAK_BLACK &&
319 object->count < object->min_count;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100320}
321
Luis R. Rodriguez4a558dd2009-09-08 16:34:50 +0100322static bool color_gray(const struct kmemleak_object *object)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100323{
Luis R. Rodrigueza1084c82009-09-04 17:44:52 -0700324 return object->min_count != KMEMLEAK_BLACK &&
325 object->count >= object->min_count;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100326}
327
328/*
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100329 * Objects are considered unreferenced only if their color is white, they have
330 * not be deleted and have a minimum age to avoid false positives caused by
331 * pointers temporarily stored in CPU registers.
332 */
Luis R. Rodriguez4a558dd2009-09-08 16:34:50 +0100333static bool unreferenced_object(struct kmemleak_object *object)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100334{
Catalin Marinas04609ccc2009-10-28 13:33:12 +0000335 return (color_white(object) && object->flags & OBJECT_ALLOCATED) &&
Catalin Marinasacf49682009-06-26 17:38:29 +0100336 time_before_eq(object->jiffies + jiffies_min_age,
337 jiffies_last_scan);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100338}
339
340/*
Catalin Marinasbab4a342009-06-26 17:38:26 +0100341 * Printing of the unreferenced objects information to the seq file. The
342 * print_unreferenced function must be called with the object->lock held.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100343 */
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100344static void print_unreferenced(struct seq_file *seq,
345 struct kmemleak_object *object)
346{
347 int i;
Catalin Marinasfefdd332009-10-28 13:33:12 +0000348 unsigned int msecs_age = jiffies_to_msecs(jiffies - object->jiffies);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100349
Catalin Marinasbab4a342009-06-26 17:38:26 +0100350 seq_printf(seq, "unreferenced object 0x%08lx (size %zu):\n",
351 object->pointer, object->size);
Catalin Marinasfefdd332009-10-28 13:33:12 +0000352 seq_printf(seq, " comm \"%s\", pid %d, jiffies %lu (age %d.%03ds)\n",
353 object->comm, object->pid, object->jiffies,
354 msecs_age / 1000, msecs_age % 1000);
Sergey Senozhatsky0494e082009-08-27 14:29:18 +0100355 hex_dump_object(seq, object);
Catalin Marinasbab4a342009-06-26 17:38:26 +0100356 seq_printf(seq, " backtrace:\n");
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100357
358 for (i = 0; i < object->trace_len; i++) {
359 void *ptr = (void *)object->trace[i];
Catalin Marinasbab4a342009-06-26 17:38:26 +0100360 seq_printf(seq, " [<%p>] %pS\n", ptr, ptr);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100361 }
362}
363
364/*
365 * Print the kmemleak_object information. This function is used mainly for
366 * debugging special cases when kmemleak operations. It must be called with
367 * the object->lock held.
368 */
369static void dump_object_info(struct kmemleak_object *object)
370{
371 struct stack_trace trace;
372
373 trace.nr_entries = object->trace_len;
374 trace.entries = object->trace;
375
Joe Perchesae281062009-06-23 14:40:26 +0100376 pr_notice("Object 0x%08lx (size %zu):\n",
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100377 object->tree_node.start, object->size);
378 pr_notice(" comm \"%s\", pid %d, jiffies %lu\n",
379 object->comm, object->pid, object->jiffies);
380 pr_notice(" min_count = %d\n", object->min_count);
381 pr_notice(" count = %d\n", object->count);
Catalin Marinas189d84e2009-08-27 14:29:15 +0100382 pr_notice(" flags = 0x%lx\n", object->flags);
Catalin Marinas04609ccc2009-10-28 13:33:12 +0000383 pr_notice(" checksum = %d\n", object->checksum);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100384 pr_notice(" backtrace:\n");
385 print_stack_trace(&trace, 4);
386}
387
388/*
389 * Look-up a memory block metadata (kmemleak_object) in the priority search
390 * tree based on a pointer value. If alias is 0, only values pointing to the
391 * beginning of the memory block are allowed. The kmemleak_lock must be held
392 * when calling this function.
393 */
394static struct kmemleak_object *lookup_object(unsigned long ptr, int alias)
395{
396 struct prio_tree_node *node;
397 struct prio_tree_iter iter;
398 struct kmemleak_object *object;
399
400 prio_tree_iter_init(&iter, &object_tree_root, ptr, ptr);
401 node = prio_tree_next(&iter);
402 if (node) {
403 object = prio_tree_entry(node, struct kmemleak_object,
404 tree_node);
405 if (!alias && object->pointer != ptr) {
Catalin Marinasa7686a42010-07-19 11:54:16 +0100406 pr_warning("Found object by alias at 0x%08lx\n", ptr);
407 dump_stack();
408 dump_object_info(object);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100409 object = NULL;
410 }
411 } else
412 object = NULL;
413
414 return object;
415}
416
417/*
418 * Increment the object use_count. Return 1 if successful or 0 otherwise. Note
419 * that once an object's use_count reached 0, the RCU freeing was already
420 * registered and the object should no longer be used. This function must be
421 * called under the protection of rcu_read_lock().
422 */
423static int get_object(struct kmemleak_object *object)
424{
425 return atomic_inc_not_zero(&object->use_count);
426}
427
428/*
429 * RCU callback to free a kmemleak_object.
430 */
431static void free_object_rcu(struct rcu_head *rcu)
432{
433 struct hlist_node *elem, *tmp;
434 struct kmemleak_scan_area *area;
435 struct kmemleak_object *object =
436 container_of(rcu, struct kmemleak_object, rcu);
437
438 /*
439 * Once use_count is 0 (guaranteed by put_object), there is no other
440 * code accessing this object, hence no need for locking.
441 */
442 hlist_for_each_entry_safe(area, elem, tmp, &object->area_list, node) {
443 hlist_del(elem);
444 kmem_cache_free(scan_area_cache, area);
445 }
446 kmem_cache_free(object_cache, object);
447}
448
449/*
450 * Decrement the object use_count. Once the count is 0, free the object using
451 * an RCU callback. Since put_object() may be called via the kmemleak_free() ->
452 * delete_object() path, the delayed RCU freeing ensures that there is no
453 * recursive call to the kernel allocator. Lock-less RCU object_list traversal
454 * is also possible.
455 */
456static void put_object(struct kmemleak_object *object)
457{
458 if (!atomic_dec_and_test(&object->use_count))
459 return;
460
461 /* should only get here after delete_object was called */
462 WARN_ON(object->flags & OBJECT_ALLOCATED);
463
464 call_rcu(&object->rcu, free_object_rcu);
465}
466
467/*
468 * Look up an object in the prio search tree and increase its use_count.
469 */
470static struct kmemleak_object *find_and_get_object(unsigned long ptr, int alias)
471{
472 unsigned long flags;
473 struct kmemleak_object *object = NULL;
474
475 rcu_read_lock();
476 read_lock_irqsave(&kmemleak_lock, flags);
477 if (ptr >= min_addr && ptr < max_addr)
478 object = lookup_object(ptr, alias);
479 read_unlock_irqrestore(&kmemleak_lock, flags);
480
481 /* check whether the object is still available */
482 if (object && !get_object(object))
483 object = NULL;
484 rcu_read_unlock();
485
486 return object;
487}
488
489/*
Catalin Marinasfd678962009-08-27 14:29:17 +0100490 * Save stack trace to the given array of MAX_TRACE size.
491 */
492static int __save_stack_trace(unsigned long *trace)
493{
494 struct stack_trace stack_trace;
495
496 stack_trace.max_entries = MAX_TRACE;
497 stack_trace.nr_entries = 0;
498 stack_trace.entries = trace;
499 stack_trace.skip = 2;
500 save_stack_trace(&stack_trace);
501
502 return stack_trace.nr_entries;
503}
504
505/*
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100506 * Create the metadata (struct kmemleak_object) corresponding to an allocated
507 * memory block and add it to the object_list and object_tree_root.
508 */
Catalin Marinasfd678962009-08-27 14:29:17 +0100509static struct kmemleak_object *create_object(unsigned long ptr, size_t size,
510 int min_count, gfp_t gfp)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100511{
512 unsigned long flags;
513 struct kmemleak_object *object;
514 struct prio_tree_node *node;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100515
Catalin Marinas6ae4bd12011-01-27 10:30:26 +0000516 object = kmem_cache_alloc(object_cache, gfp_kmemleak_mask(gfp));
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100517 if (!object) {
Catalin Marinas6ae4bd12011-01-27 10:30:26 +0000518 pr_warning("Cannot allocate a kmemleak_object structure\n");
519 kmemleak_disable();
Catalin Marinasfd678962009-08-27 14:29:17 +0100520 return NULL;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100521 }
522
523 INIT_LIST_HEAD(&object->object_list);
524 INIT_LIST_HEAD(&object->gray_list);
525 INIT_HLIST_HEAD(&object->area_list);
526 spin_lock_init(&object->lock);
527 atomic_set(&object->use_count, 1);
Catalin Marinas04609ccc2009-10-28 13:33:12 +0000528 object->flags = OBJECT_ALLOCATED;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100529 object->pointer = ptr;
530 object->size = size;
531 object->min_count = min_count;
Catalin Marinas04609ccc2009-10-28 13:33:12 +0000532 object->count = 0; /* white color initially */
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100533 object->jiffies = jiffies;
Catalin Marinas04609ccc2009-10-28 13:33:12 +0000534 object->checksum = 0;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100535
536 /* task information */
537 if (in_irq()) {
538 object->pid = 0;
539 strncpy(object->comm, "hardirq", sizeof(object->comm));
540 } else if (in_softirq()) {
541 object->pid = 0;
542 strncpy(object->comm, "softirq", sizeof(object->comm));
543 } else {
544 object->pid = current->pid;
545 /*
546 * There is a small chance of a race with set_task_comm(),
547 * however using get_task_comm() here may cause locking
548 * dependency issues with current->alloc_lock. In the worst
549 * case, the command line is not correct.
550 */
551 strncpy(object->comm, current->comm, sizeof(object->comm));
552 }
553
554 /* kernel backtrace */
Catalin Marinasfd678962009-08-27 14:29:17 +0100555 object->trace_len = __save_stack_trace(object->trace);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100556
557 INIT_PRIO_TREE_NODE(&object->tree_node);
558 object->tree_node.start = ptr;
559 object->tree_node.last = ptr + size - 1;
560
561 write_lock_irqsave(&kmemleak_lock, flags);
Luis R. Rodriguez0580a182009-09-08 17:32:34 +0100562
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100563 min_addr = min(min_addr, ptr);
564 max_addr = max(max_addr, ptr + size);
565 node = prio_tree_insert(&object_tree_root, &object->tree_node);
566 /*
567 * The code calling the kernel does not yet have the pointer to the
568 * memory block to be able to free it. However, we still hold the
569 * kmemleak_lock here in case parts of the kernel started freeing
570 * random memory blocks.
571 */
572 if (node != &object->tree_node) {
Joe Perchesae281062009-06-23 14:40:26 +0100573 kmemleak_stop("Cannot insert 0x%lx into the object search tree "
574 "(already existing)\n", ptr);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100575 object = lookup_object(ptr, 1);
Luis R. Rodriguez0580a182009-09-08 17:32:34 +0100576 spin_lock(&object->lock);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100577 dump_object_info(object);
Luis R. Rodriguez0580a182009-09-08 17:32:34 +0100578 spin_unlock(&object->lock);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100579
580 goto out;
581 }
582 list_add_tail_rcu(&object->object_list, &object_list);
583out:
584 write_unlock_irqrestore(&kmemleak_lock, flags);
Catalin Marinasfd678962009-08-27 14:29:17 +0100585 return object;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100586}
587
588/*
589 * Remove the metadata (struct kmemleak_object) for a memory block from the
590 * object_list and object_tree_root and decrement its use_count.
591 */
Catalin Marinas53238a62009-07-07 10:33:00 +0100592static void __delete_object(struct kmemleak_object *object)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100593{
594 unsigned long flags;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100595
596 write_lock_irqsave(&kmemleak_lock, flags);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100597 prio_tree_remove(&object_tree_root, &object->tree_node);
598 list_del_rcu(&object->object_list);
599 write_unlock_irqrestore(&kmemleak_lock, flags);
600
601 WARN_ON(!(object->flags & OBJECT_ALLOCATED));
Catalin Marinas53238a62009-07-07 10:33:00 +0100602 WARN_ON(atomic_read(&object->use_count) < 2);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100603
604 /*
605 * Locking here also ensures that the corresponding memory block
606 * cannot be freed when it is being scanned.
607 */
608 spin_lock_irqsave(&object->lock, flags);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100609 object->flags &= ~OBJECT_ALLOCATED;
610 spin_unlock_irqrestore(&object->lock, flags);
611 put_object(object);
612}
613
614/*
Catalin Marinas53238a62009-07-07 10:33:00 +0100615 * Look up the metadata (struct kmemleak_object) corresponding to ptr and
616 * delete it.
617 */
618static void delete_object_full(unsigned long ptr)
619{
620 struct kmemleak_object *object;
621
622 object = find_and_get_object(ptr, 0);
623 if (!object) {
624#ifdef DEBUG
625 kmemleak_warn("Freeing unknown object at 0x%08lx\n",
626 ptr);
627#endif
628 return;
629 }
630 __delete_object(object);
631 put_object(object);
632}
633
634/*
635 * Look up the metadata (struct kmemleak_object) corresponding to ptr and
636 * delete it. If the memory block is partially freed, the function may create
637 * additional metadata for the remaining parts of the block.
638 */
639static void delete_object_part(unsigned long ptr, size_t size)
640{
641 struct kmemleak_object *object;
642 unsigned long start, end;
643
644 object = find_and_get_object(ptr, 1);
645 if (!object) {
646#ifdef DEBUG
647 kmemleak_warn("Partially freeing unknown object at 0x%08lx "
648 "(size %zu)\n", ptr, size);
649#endif
650 return;
651 }
652 __delete_object(object);
653
654 /*
655 * Create one or two objects that may result from the memory block
656 * split. Note that partial freeing is only done by free_bootmem() and
657 * this happens before kmemleak_init() is called. The path below is
658 * only executed during early log recording in kmemleak_init(), so
659 * GFP_KERNEL is enough.
660 */
661 start = object->pointer;
662 end = object->pointer + object->size;
663 if (ptr > start)
664 create_object(start, ptr - start, object->min_count,
665 GFP_KERNEL);
666 if (ptr + size < end)
667 create_object(ptr + size, end - ptr - size, object->min_count,
668 GFP_KERNEL);
669
670 put_object(object);
671}
Luis R. Rodrigueza1084c82009-09-04 17:44:52 -0700672
673static void __paint_it(struct kmemleak_object *object, int color)
674{
675 object->min_count = color;
676 if (color == KMEMLEAK_BLACK)
677 object->flags |= OBJECT_NO_SCAN;
678}
679
680static void paint_it(struct kmemleak_object *object, int color)
681{
682 unsigned long flags;
683
684 spin_lock_irqsave(&object->lock, flags);
685 __paint_it(object, color);
686 spin_unlock_irqrestore(&object->lock, flags);
687}
688
689static void paint_ptr(unsigned long ptr, int color)
690{
691 struct kmemleak_object *object;
692
693 object = find_and_get_object(ptr, 0);
694 if (!object) {
695 kmemleak_warn("Trying to color unknown object "
696 "at 0x%08lx as %s\n", ptr,
697 (color == KMEMLEAK_GREY) ? "Grey" :
698 (color == KMEMLEAK_BLACK) ? "Black" : "Unknown");
699 return;
700 }
701 paint_it(object, color);
702 put_object(object);
703}
704
Catalin Marinas53238a62009-07-07 10:33:00 +0100705/*
Holger Hans Peter Freyther145b64b2010-07-22 19:54:13 +0800706 * Mark an object permanently as gray-colored so that it can no longer be
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100707 * reported as a leak. This is used in general to mark a false positive.
708 */
709static void make_gray_object(unsigned long ptr)
710{
Luis R. Rodrigueza1084c82009-09-04 17:44:52 -0700711 paint_ptr(ptr, KMEMLEAK_GREY);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100712}
713
714/*
715 * Mark the object as black-colored so that it is ignored from scans and
716 * reporting.
717 */
718static void make_black_object(unsigned long ptr)
719{
Luis R. Rodrigueza1084c82009-09-04 17:44:52 -0700720 paint_ptr(ptr, KMEMLEAK_BLACK);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100721}
722
723/*
724 * Add a scanning area to the object. If at least one such area is added,
725 * kmemleak will only scan these ranges rather than the whole memory block.
726 */
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000727static void add_scan_area(unsigned long ptr, size_t size, gfp_t gfp)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100728{
729 unsigned long flags;
730 struct kmemleak_object *object;
731 struct kmemleak_scan_area *area;
732
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000733 object = find_and_get_object(ptr, 1);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100734 if (!object) {
Joe Perchesae281062009-06-23 14:40:26 +0100735 kmemleak_warn("Adding scan area to unknown object at 0x%08lx\n",
736 ptr);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100737 return;
738 }
739
Catalin Marinas6ae4bd12011-01-27 10:30:26 +0000740 area = kmem_cache_alloc(scan_area_cache, gfp_kmemleak_mask(gfp));
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100741 if (!area) {
Catalin Marinas6ae4bd12011-01-27 10:30:26 +0000742 pr_warning("Cannot allocate a scan area\n");
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100743 goto out;
744 }
745
746 spin_lock_irqsave(&object->lock, flags);
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000747 if (ptr + size > object->pointer + object->size) {
Joe Perchesae281062009-06-23 14:40:26 +0100748 kmemleak_warn("Scan area larger than object 0x%08lx\n", ptr);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100749 dump_object_info(object);
750 kmem_cache_free(scan_area_cache, area);
751 goto out_unlock;
752 }
753
754 INIT_HLIST_NODE(&area->node);
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000755 area->start = ptr;
756 area->size = size;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100757
758 hlist_add_head(&area->node, &object->area_list);
759out_unlock:
760 spin_unlock_irqrestore(&object->lock, flags);
761out:
762 put_object(object);
763}
764
765/*
766 * Set the OBJECT_NO_SCAN flag for the object corresponding to the give
767 * pointer. Such object will not be scanned by kmemleak but references to it
768 * are searched.
769 */
770static void object_no_scan(unsigned long ptr)
771{
772 unsigned long flags;
773 struct kmemleak_object *object;
774
775 object = find_and_get_object(ptr, 0);
776 if (!object) {
Joe Perchesae281062009-06-23 14:40:26 +0100777 kmemleak_warn("Not scanning unknown object at 0x%08lx\n", ptr);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100778 return;
779 }
780
781 spin_lock_irqsave(&object->lock, flags);
782 object->flags |= OBJECT_NO_SCAN;
783 spin_unlock_irqrestore(&object->lock, flags);
784 put_object(object);
785}
786
787/*
788 * Log an early kmemleak_* call to the early_log buffer. These calls will be
789 * processed later once kmemleak is fully initialized.
790 */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100791static void __init log_early(int op_type, const void *ptr, size_t size,
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000792 int min_count)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100793{
794 unsigned long flags;
795 struct early_log *log;
796
797 if (crt_early_log >= ARRAY_SIZE(early_log)) {
Catalin Marinasaddd72c2009-09-11 10:42:09 +0100798 pr_warning("Early log buffer exceeded, "
799 "please increase DEBUG_KMEMLEAK_EARLY_LOG_SIZE\n");
Catalin Marinasa9d90582009-06-25 10:16:11 +0100800 kmemleak_disable();
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100801 return;
802 }
803
804 /*
805 * There is no need for locking since the kernel is still in UP mode
806 * at this stage. Disabling the IRQs is enough.
807 */
808 local_irq_save(flags);
809 log = &early_log[crt_early_log];
810 log->op_type = op_type;
811 log->ptr = ptr;
812 log->size = size;
813 log->min_count = min_count;
Catalin Marinasfd678962009-08-27 14:29:17 +0100814 if (op_type == KMEMLEAK_ALLOC)
815 log->trace_len = __save_stack_trace(log->trace);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100816 crt_early_log++;
817 local_irq_restore(flags);
818}
819
820/*
Catalin Marinasfd678962009-08-27 14:29:17 +0100821 * Log an early allocated block and populate the stack trace.
822 */
823static void early_alloc(struct early_log *log)
824{
825 struct kmemleak_object *object;
826 unsigned long flags;
827 int i;
828
829 if (!atomic_read(&kmemleak_enabled) || !log->ptr || IS_ERR(log->ptr))
830 return;
831
832 /*
833 * RCU locking needed to ensure object is not freed via put_object().
834 */
835 rcu_read_lock();
836 object = create_object((unsigned long)log->ptr, log->size,
Tetsuo Handac1bcd6b2009-10-09 10:39:24 +0100837 log->min_count, GFP_ATOMIC);
Catalin Marinas0d5d1aa2009-10-09 10:30:34 +0100838 if (!object)
839 goto out;
Catalin Marinasfd678962009-08-27 14:29:17 +0100840 spin_lock_irqsave(&object->lock, flags);
841 for (i = 0; i < log->trace_len; i++)
842 object->trace[i] = log->trace[i];
843 object->trace_len = log->trace_len;
844 spin_unlock_irqrestore(&object->lock, flags);
Catalin Marinas0d5d1aa2009-10-09 10:30:34 +0100845out:
Catalin Marinasfd678962009-08-27 14:29:17 +0100846 rcu_read_unlock();
847}
848
Catalin Marinasa2b6bf62010-07-19 11:54:17 +0100849/**
850 * kmemleak_alloc - register a newly allocated object
851 * @ptr: pointer to beginning of the object
852 * @size: size of the object
853 * @min_count: minimum number of references to this object. If during memory
854 * scanning a number of references less than @min_count is found,
855 * the object is reported as a memory leak. If @min_count is 0,
856 * the object is never reported as a leak. If @min_count is -1,
857 * the object is ignored (not scanned and not reported as a leak)
858 * @gfp: kmalloc() flags used for kmemleak internal memory allocations
859 *
860 * This function is called from the kernel allocators when a new object
861 * (memory block) is allocated (kmem_cache_alloc, kmalloc, vmalloc etc.).
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100862 */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100863void __ref kmemleak_alloc(const void *ptr, size_t size, int min_count,
864 gfp_t gfp)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100865{
866 pr_debug("%s(0x%p, %zu, %d)\n", __func__, ptr, size, min_count);
867
868 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
869 create_object((unsigned long)ptr, size, min_count, gfp);
870 else if (atomic_read(&kmemleak_early_log))
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000871 log_early(KMEMLEAK_ALLOC, ptr, size, min_count);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100872}
873EXPORT_SYMBOL_GPL(kmemleak_alloc);
874
Catalin Marinasa2b6bf62010-07-19 11:54:17 +0100875/**
876 * kmemleak_free - unregister a previously registered object
877 * @ptr: pointer to beginning of the object
878 *
879 * This function is called from the kernel allocators when an object (memory
880 * block) is freed (kmem_cache_free, kfree, vfree etc.).
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100881 */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100882void __ref kmemleak_free(const void *ptr)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100883{
884 pr_debug("%s(0x%p)\n", __func__, ptr);
885
886 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
Catalin Marinas53238a62009-07-07 10:33:00 +0100887 delete_object_full((unsigned long)ptr);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100888 else if (atomic_read(&kmemleak_early_log))
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000889 log_early(KMEMLEAK_FREE, ptr, 0, 0);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100890}
891EXPORT_SYMBOL_GPL(kmemleak_free);
892
Catalin Marinasa2b6bf62010-07-19 11:54:17 +0100893/**
894 * kmemleak_free_part - partially unregister a previously registered object
895 * @ptr: pointer to the beginning or inside the object. This also
896 * represents the start of the range to be freed
897 * @size: size to be unregistered
898 *
899 * This function is called when only a part of a memory block is freed
900 * (usually from the bootmem allocator).
Catalin Marinas53238a62009-07-07 10:33:00 +0100901 */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100902void __ref kmemleak_free_part(const void *ptr, size_t size)
Catalin Marinas53238a62009-07-07 10:33:00 +0100903{
904 pr_debug("%s(0x%p)\n", __func__, ptr);
905
906 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
907 delete_object_part((unsigned long)ptr, size);
908 else if (atomic_read(&kmemleak_early_log))
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000909 log_early(KMEMLEAK_FREE_PART, ptr, size, 0);
Catalin Marinas53238a62009-07-07 10:33:00 +0100910}
911EXPORT_SYMBOL_GPL(kmemleak_free_part);
912
Catalin Marinasa2b6bf62010-07-19 11:54:17 +0100913/**
914 * kmemleak_not_leak - mark an allocated object as false positive
915 * @ptr: pointer to beginning of the object
916 *
917 * Calling this function on an object will cause the memory block to no longer
918 * be reported as leak and always be scanned.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100919 */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100920void __ref kmemleak_not_leak(const void *ptr)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100921{
922 pr_debug("%s(0x%p)\n", __func__, ptr);
923
924 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
925 make_gray_object((unsigned long)ptr);
926 else if (atomic_read(&kmemleak_early_log))
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000927 log_early(KMEMLEAK_NOT_LEAK, ptr, 0, 0);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100928}
929EXPORT_SYMBOL(kmemleak_not_leak);
930
Catalin Marinasa2b6bf62010-07-19 11:54:17 +0100931/**
932 * kmemleak_ignore - ignore an allocated object
933 * @ptr: pointer to beginning of the object
934 *
935 * Calling this function on an object will cause the memory block to be
936 * ignored (not scanned and not reported as a leak). This is usually done when
937 * it is known that the corresponding block is not a leak and does not contain
938 * any references to other allocated memory blocks.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100939 */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100940void __ref kmemleak_ignore(const void *ptr)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100941{
942 pr_debug("%s(0x%p)\n", __func__, ptr);
943
944 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
945 make_black_object((unsigned long)ptr);
946 else if (atomic_read(&kmemleak_early_log))
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000947 log_early(KMEMLEAK_IGNORE, ptr, 0, 0);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100948}
949EXPORT_SYMBOL(kmemleak_ignore);
950
Catalin Marinasa2b6bf62010-07-19 11:54:17 +0100951/**
952 * kmemleak_scan_area - limit the range to be scanned in an allocated object
953 * @ptr: pointer to beginning or inside the object. This also
954 * represents the start of the scan area
955 * @size: size of the scan area
956 * @gfp: kmalloc() flags used for kmemleak internal memory allocations
957 *
958 * This function is used when it is known that only certain parts of an object
959 * contain references to other objects. Kmemleak will only scan these areas
960 * reducing the number false negatives.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100961 */
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000962void __ref kmemleak_scan_area(const void *ptr, size_t size, gfp_t gfp)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100963{
964 pr_debug("%s(0x%p)\n", __func__, ptr);
965
966 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000967 add_scan_area((unsigned long)ptr, size, gfp);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100968 else if (atomic_read(&kmemleak_early_log))
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000969 log_early(KMEMLEAK_SCAN_AREA, ptr, size, 0);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100970}
971EXPORT_SYMBOL(kmemleak_scan_area);
972
Catalin Marinasa2b6bf62010-07-19 11:54:17 +0100973/**
974 * kmemleak_no_scan - do not scan an allocated object
975 * @ptr: pointer to beginning of the object
976 *
977 * This function notifies kmemleak not to scan the given memory block. Useful
978 * in situations where it is known that the given object does not contain any
979 * references to other objects. Kmemleak will not scan such objects reducing
980 * the number of false negatives.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100981 */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100982void __ref kmemleak_no_scan(const void *ptr)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100983{
984 pr_debug("%s(0x%p)\n", __func__, ptr);
985
986 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
987 object_no_scan((unsigned long)ptr);
988 else if (atomic_read(&kmemleak_early_log))
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000989 log_early(KMEMLEAK_NO_SCAN, ptr, 0, 0);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100990}
991EXPORT_SYMBOL(kmemleak_no_scan);
992
993/*
Catalin Marinas04609ccc2009-10-28 13:33:12 +0000994 * Update an object's checksum and return true if it was modified.
995 */
996static bool update_checksum(struct kmemleak_object *object)
997{
998 u32 old_csum = object->checksum;
999
1000 if (!kmemcheck_is_obj_initialized(object->pointer, object->size))
1001 return false;
1002
1003 object->checksum = crc32(0, (void *)object->pointer, object->size);
1004 return object->checksum != old_csum;
1005}
1006
1007/*
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001008 * Memory scanning is a long process and it needs to be interruptable. This
Lucas De Marchi25985ed2011-03-30 22:57:33 -03001009 * function checks whether such interrupt condition occurred.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001010 */
1011static int scan_should_stop(void)
1012{
1013 if (!atomic_read(&kmemleak_enabled))
1014 return 1;
1015
1016 /*
1017 * This function may be called from either process or kthread context,
1018 * hence the need to check for both stop conditions.
1019 */
1020 if (current->mm)
1021 return signal_pending(current);
1022 else
1023 return kthread_should_stop();
1024
1025 return 0;
1026}
1027
1028/*
1029 * Scan a memory block (exclusive range) for valid pointers and add those
1030 * found to the gray list.
1031 */
1032static void scan_block(void *_start, void *_end,
Catalin Marinas4b8a9672009-07-07 10:32:56 +01001033 struct kmemleak_object *scanned, int allow_resched)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001034{
1035 unsigned long *ptr;
1036 unsigned long *start = PTR_ALIGN(_start, BYTES_PER_POINTER);
1037 unsigned long *end = _end - (BYTES_PER_POINTER - 1);
1038
1039 for (ptr = start; ptr < end; ptr++) {
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001040 struct kmemleak_object *object;
Pekka Enberg8e019362009-08-27 14:50:00 +01001041 unsigned long flags;
1042 unsigned long pointer;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001043
Catalin Marinas4b8a9672009-07-07 10:32:56 +01001044 if (allow_resched)
1045 cond_resched();
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001046 if (scan_should_stop())
1047 break;
1048
Pekka Enberg8e019362009-08-27 14:50:00 +01001049 /* don't scan uninitialized memory */
1050 if (!kmemcheck_is_obj_initialized((unsigned long)ptr,
1051 BYTES_PER_POINTER))
1052 continue;
1053
1054 pointer = *ptr;
1055
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001056 object = find_and_get_object(pointer, 1);
1057 if (!object)
1058 continue;
1059 if (object == scanned) {
1060 /* self referenced, ignore */
1061 put_object(object);
1062 continue;
1063 }
1064
1065 /*
1066 * Avoid the lockdep recursive warning on object->lock being
1067 * previously acquired in scan_object(). These locks are
1068 * enclosed by scan_mutex.
1069 */
1070 spin_lock_irqsave_nested(&object->lock, flags,
1071 SINGLE_DEPTH_NESTING);
1072 if (!color_white(object)) {
1073 /* non-orphan, ignored or new */
1074 spin_unlock_irqrestore(&object->lock, flags);
1075 put_object(object);
1076 continue;
1077 }
1078
1079 /*
1080 * Increase the object's reference count (number of pointers
1081 * to the memory block). If this count reaches the required
1082 * minimum, the object's color will become gray and it will be
1083 * added to the gray_list.
1084 */
1085 object->count++;
Catalin Marinas0587da42009-10-28 13:33:11 +00001086 if (color_gray(object)) {
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001087 list_add_tail(&object->gray_list, &gray_list);
Catalin Marinas0587da42009-10-28 13:33:11 +00001088 spin_unlock_irqrestore(&object->lock, flags);
1089 continue;
1090 }
1091
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001092 spin_unlock_irqrestore(&object->lock, flags);
Catalin Marinas0587da42009-10-28 13:33:11 +00001093 put_object(object);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001094 }
1095}
1096
1097/*
1098 * Scan a memory block corresponding to a kmemleak_object. A condition is
1099 * that object->use_count >= 1.
1100 */
1101static void scan_object(struct kmemleak_object *object)
1102{
1103 struct kmemleak_scan_area *area;
1104 struct hlist_node *elem;
1105 unsigned long flags;
1106
1107 /*
Uwe Kleine-König21ae2952009-10-07 15:21:09 +02001108 * Once the object->lock is acquired, the corresponding memory block
1109 * cannot be freed (the same lock is acquired in delete_object).
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001110 */
1111 spin_lock_irqsave(&object->lock, flags);
1112 if (object->flags & OBJECT_NO_SCAN)
1113 goto out;
1114 if (!(object->flags & OBJECT_ALLOCATED))
1115 /* already freed object */
1116 goto out;
Catalin Marinasaf986032009-08-27 14:29:12 +01001117 if (hlist_empty(&object->area_list)) {
1118 void *start = (void *)object->pointer;
1119 void *end = (void *)(object->pointer + object->size);
1120
1121 while (start < end && (object->flags & OBJECT_ALLOCATED) &&
1122 !(object->flags & OBJECT_NO_SCAN)) {
1123 scan_block(start, min(start + MAX_SCAN_SIZE, end),
1124 object, 0);
1125 start += MAX_SCAN_SIZE;
1126
1127 spin_unlock_irqrestore(&object->lock, flags);
1128 cond_resched();
1129 spin_lock_irqsave(&object->lock, flags);
1130 }
1131 } else
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001132 hlist_for_each_entry(area, elem, &object->area_list, node)
Catalin Marinasc017b4b2009-10-28 13:33:09 +00001133 scan_block((void *)area->start,
1134 (void *)(area->start + area->size),
1135 object, 0);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001136out:
1137 spin_unlock_irqrestore(&object->lock, flags);
1138}
1139
1140/*
Catalin Marinas04609ccc2009-10-28 13:33:12 +00001141 * Scan the objects already referenced (gray objects). More objects will be
1142 * referenced and, if there are no memory leaks, all the objects are scanned.
1143 */
1144static void scan_gray_list(void)
1145{
1146 struct kmemleak_object *object, *tmp;
1147
1148 /*
1149 * The list traversal is safe for both tail additions and removals
1150 * from inside the loop. The kmemleak objects cannot be freed from
1151 * outside the loop because their use_count was incremented.
1152 */
1153 object = list_entry(gray_list.next, typeof(*object), gray_list);
1154 while (&object->gray_list != &gray_list) {
1155 cond_resched();
1156
1157 /* may add new objects to the list */
1158 if (!scan_should_stop())
1159 scan_object(object);
1160
1161 tmp = list_entry(object->gray_list.next, typeof(*object),
1162 gray_list);
1163
1164 /* remove the object from the list and release it */
1165 list_del(&object->gray_list);
1166 put_object(object);
1167
1168 object = tmp;
1169 }
1170 WARN_ON(!list_empty(&gray_list));
1171}
1172
1173/*
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001174 * Scan data sections and all the referenced memory blocks allocated via the
1175 * kernel's standard allocators. This function must be called with the
1176 * scan_mutex held.
1177 */
1178static void kmemleak_scan(void)
1179{
1180 unsigned long flags;
Catalin Marinas04609ccc2009-10-28 13:33:12 +00001181 struct kmemleak_object *object;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001182 int i;
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001183 int new_leaks = 0;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001184
Catalin Marinasacf49682009-06-26 17:38:29 +01001185 jiffies_last_scan = jiffies;
1186
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001187 /* prepare the kmemleak_object's */
1188 rcu_read_lock();
1189 list_for_each_entry_rcu(object, &object_list, object_list) {
1190 spin_lock_irqsave(&object->lock, flags);
1191#ifdef DEBUG
1192 /*
1193 * With a few exceptions there should be a maximum of
1194 * 1 reference to any object at this point.
1195 */
1196 if (atomic_read(&object->use_count) > 1) {
Joe Perchesae281062009-06-23 14:40:26 +01001197 pr_debug("object->use_count = %d\n",
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001198 atomic_read(&object->use_count));
1199 dump_object_info(object);
1200 }
1201#endif
1202 /* reset the reference count (whiten the object) */
1203 object->count = 0;
1204 if (color_gray(object) && get_object(object))
1205 list_add_tail(&object->gray_list, &gray_list);
1206
1207 spin_unlock_irqrestore(&object->lock, flags);
1208 }
1209 rcu_read_unlock();
1210
1211 /* data/bss scanning */
Catalin Marinas4b8a9672009-07-07 10:32:56 +01001212 scan_block(_sdata, _edata, NULL, 1);
1213 scan_block(__bss_start, __bss_stop, NULL, 1);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001214
1215#ifdef CONFIG_SMP
1216 /* per-cpu sections scanning */
1217 for_each_possible_cpu(i)
1218 scan_block(__per_cpu_start + per_cpu_offset(i),
Catalin Marinas4b8a9672009-07-07 10:32:56 +01001219 __per_cpu_end + per_cpu_offset(i), NULL, 1);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001220#endif
1221
1222 /*
1223 * Struct page scanning for each node. The code below is not yet safe
1224 * with MEMORY_HOTPLUG.
1225 */
1226 for_each_online_node(i) {
1227 pg_data_t *pgdat = NODE_DATA(i);
1228 unsigned long start_pfn = pgdat->node_start_pfn;
1229 unsigned long end_pfn = start_pfn + pgdat->node_spanned_pages;
1230 unsigned long pfn;
1231
1232 for (pfn = start_pfn; pfn < end_pfn; pfn++) {
1233 struct page *page;
1234
1235 if (!pfn_valid(pfn))
1236 continue;
1237 page = pfn_to_page(pfn);
1238 /* only scan if page is in use */
1239 if (page_count(page) == 0)
1240 continue;
Catalin Marinas4b8a9672009-07-07 10:32:56 +01001241 scan_block(page, page + 1, NULL, 1);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001242 }
1243 }
1244
1245 /*
Catalin Marinas43ed5d62009-09-01 11:12:44 +01001246 * Scanning the task stacks (may introduce false negatives).
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001247 */
1248 if (kmemleak_stack_scan) {
Catalin Marinas43ed5d62009-09-01 11:12:44 +01001249 struct task_struct *p, *g;
1250
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001251 read_lock(&tasklist_lock);
Catalin Marinas43ed5d62009-09-01 11:12:44 +01001252 do_each_thread(g, p) {
1253 scan_block(task_stack_page(p), task_stack_page(p) +
1254 THREAD_SIZE, NULL, 0);
1255 } while_each_thread(g, p);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001256 read_unlock(&tasklist_lock);
1257 }
1258
1259 /*
1260 * Scan the objects already referenced from the sections scanned
Catalin Marinas04609ccc2009-10-28 13:33:12 +00001261 * above.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001262 */
Catalin Marinas04609ccc2009-10-28 13:33:12 +00001263 scan_gray_list();
Catalin Marinas25873622009-07-07 10:32:58 +01001264
1265 /*
Catalin Marinas04609ccc2009-10-28 13:33:12 +00001266 * Check for new or unreferenced objects modified since the previous
1267 * scan and color them gray until the next scan.
Catalin Marinas25873622009-07-07 10:32:58 +01001268 */
1269 rcu_read_lock();
1270 list_for_each_entry_rcu(object, &object_list, object_list) {
1271 spin_lock_irqsave(&object->lock, flags);
Catalin Marinas04609ccc2009-10-28 13:33:12 +00001272 if (color_white(object) && (object->flags & OBJECT_ALLOCATED)
1273 && update_checksum(object) && get_object(object)) {
1274 /* color it gray temporarily */
1275 object->count = object->min_count;
Catalin Marinas25873622009-07-07 10:32:58 +01001276 list_add_tail(&object->gray_list, &gray_list);
1277 }
1278 spin_unlock_irqrestore(&object->lock, flags);
1279 }
1280 rcu_read_unlock();
1281
Catalin Marinas04609ccc2009-10-28 13:33:12 +00001282 /*
1283 * Re-scan the gray list for modified unreferenced objects.
1284 */
1285 scan_gray_list();
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001286
1287 /*
Catalin Marinas04609ccc2009-10-28 13:33:12 +00001288 * If scanning was stopped do not report any new unreferenced objects.
Catalin Marinas17bb9e02009-06-29 17:13:56 +01001289 */
Catalin Marinas04609ccc2009-10-28 13:33:12 +00001290 if (scan_should_stop())
Catalin Marinas17bb9e02009-06-29 17:13:56 +01001291 return;
1292
1293 /*
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001294 * Scanning result reporting.
1295 */
1296 rcu_read_lock();
1297 list_for_each_entry_rcu(object, &object_list, object_list) {
1298 spin_lock_irqsave(&object->lock, flags);
1299 if (unreferenced_object(object) &&
1300 !(object->flags & OBJECT_REPORTED)) {
1301 object->flags |= OBJECT_REPORTED;
1302 new_leaks++;
1303 }
1304 spin_unlock_irqrestore(&object->lock, flags);
1305 }
1306 rcu_read_unlock();
1307
1308 if (new_leaks)
1309 pr_info("%d new suspected memory leaks (see "
1310 "/sys/kernel/debug/kmemleak)\n", new_leaks);
1311
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001312}
1313
1314/*
1315 * Thread function performing automatic memory scanning. Unreferenced objects
1316 * at the end of a memory scan are reported but only the first time.
1317 */
1318static int kmemleak_scan_thread(void *arg)
1319{
1320 static int first_run = 1;
1321
Joe Perchesae281062009-06-23 14:40:26 +01001322 pr_info("Automatic memory scanning thread started\n");
Catalin Marinasbf2a76b2009-07-07 10:32:55 +01001323 set_user_nice(current, 10);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001324
1325 /*
1326 * Wait before the first scan to allow the system to fully initialize.
1327 */
1328 if (first_run) {
1329 first_run = 0;
1330 ssleep(SECS_FIRST_SCAN);
1331 }
1332
1333 while (!kthread_should_stop()) {
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001334 signed long timeout = jiffies_scan_wait;
1335
1336 mutex_lock(&scan_mutex);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001337 kmemleak_scan();
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001338 mutex_unlock(&scan_mutex);
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001339
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001340 /* wait before the next scan */
1341 while (timeout && !kthread_should_stop())
1342 timeout = schedule_timeout_interruptible(timeout);
1343 }
1344
Joe Perchesae281062009-06-23 14:40:26 +01001345 pr_info("Automatic memory scanning thread ended\n");
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001346
1347 return 0;
1348}
1349
1350/*
1351 * Start the automatic memory scanning thread. This function must be called
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001352 * with the scan_mutex held.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001353 */
Luis R. Rodriguez7eb0d5e2009-09-08 17:31:45 +01001354static void start_scan_thread(void)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001355{
1356 if (scan_thread)
1357 return;
1358 scan_thread = kthread_run(kmemleak_scan_thread, NULL, "kmemleak");
1359 if (IS_ERR(scan_thread)) {
Joe Perchesae281062009-06-23 14:40:26 +01001360 pr_warning("Failed to create the scan thread\n");
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001361 scan_thread = NULL;
1362 }
1363}
1364
1365/*
1366 * Stop the automatic memory scanning thread. This function must be called
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001367 * with the scan_mutex held.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001368 */
Luis R. Rodriguez7eb0d5e2009-09-08 17:31:45 +01001369static void stop_scan_thread(void)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001370{
1371 if (scan_thread) {
1372 kthread_stop(scan_thread);
1373 scan_thread = NULL;
1374 }
1375}
1376
1377/*
1378 * Iterate over the object_list and return the first valid object at or after
1379 * the required position with its use_count incremented. The function triggers
1380 * a memory scanning when the pos argument points to the first position.
1381 */
1382static void *kmemleak_seq_start(struct seq_file *seq, loff_t *pos)
1383{
1384 struct kmemleak_object *object;
1385 loff_t n = *pos;
Catalin Marinasb87324d2009-07-07 10:32:58 +01001386 int err;
1387
1388 err = mutex_lock_interruptible(&scan_mutex);
1389 if (err < 0)
1390 return ERR_PTR(err);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001391
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001392 rcu_read_lock();
1393 list_for_each_entry_rcu(object, &object_list, object_list) {
1394 if (n-- > 0)
1395 continue;
1396 if (get_object(object))
1397 goto out;
1398 }
1399 object = NULL;
1400out:
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001401 return object;
1402}
1403
1404/*
1405 * Return the next object in the object_list. The function decrements the
1406 * use_count of the previous object and increases that of the next one.
1407 */
1408static void *kmemleak_seq_next(struct seq_file *seq, void *v, loff_t *pos)
1409{
1410 struct kmemleak_object *prev_obj = v;
1411 struct kmemleak_object *next_obj = NULL;
1412 struct list_head *n = &prev_obj->object_list;
1413
1414 ++(*pos);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001415
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001416 list_for_each_continue_rcu(n, &object_list) {
Catalin Marinas52c3ce42011-04-27 16:44:26 +01001417 struct kmemleak_object *obj =
1418 list_entry(n, struct kmemleak_object, object_list);
1419 if (get_object(obj)) {
1420 next_obj = obj;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001421 break;
Catalin Marinas52c3ce42011-04-27 16:44:26 +01001422 }
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001423 }
Catalin Marinas288c8572009-07-07 10:32:57 +01001424
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001425 put_object(prev_obj);
1426 return next_obj;
1427}
1428
1429/*
1430 * Decrement the use_count of the last object required, if any.
1431 */
1432static void kmemleak_seq_stop(struct seq_file *seq, void *v)
1433{
Catalin Marinasb87324d2009-07-07 10:32:58 +01001434 if (!IS_ERR(v)) {
1435 /*
1436 * kmemleak_seq_start may return ERR_PTR if the scan_mutex
1437 * waiting was interrupted, so only release it if !IS_ERR.
1438 */
Catalin Marinasf5886c72009-07-29 16:26:57 +01001439 rcu_read_unlock();
Catalin Marinasb87324d2009-07-07 10:32:58 +01001440 mutex_unlock(&scan_mutex);
1441 if (v)
1442 put_object(v);
1443 }
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001444}
1445
1446/*
1447 * Print the information for an unreferenced object to the seq file.
1448 */
1449static int kmemleak_seq_show(struct seq_file *seq, void *v)
1450{
1451 struct kmemleak_object *object = v;
1452 unsigned long flags;
1453
1454 spin_lock_irqsave(&object->lock, flags);
Catalin Marinas288c8572009-07-07 10:32:57 +01001455 if ((object->flags & OBJECT_REPORTED) && unreferenced_object(object))
Catalin Marinas17bb9e02009-06-29 17:13:56 +01001456 print_unreferenced(seq, object);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001457 spin_unlock_irqrestore(&object->lock, flags);
1458 return 0;
1459}
1460
1461static const struct seq_operations kmemleak_seq_ops = {
1462 .start = kmemleak_seq_start,
1463 .next = kmemleak_seq_next,
1464 .stop = kmemleak_seq_stop,
1465 .show = kmemleak_seq_show,
1466};
1467
1468static int kmemleak_open(struct inode *inode, struct file *file)
1469{
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001470 if (!atomic_read(&kmemleak_enabled))
1471 return -EBUSY;
1472
Catalin Marinasb87324d2009-07-07 10:32:58 +01001473 return seq_open(file, &kmemleak_seq_ops);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001474}
1475
1476static int kmemleak_release(struct inode *inode, struct file *file)
1477{
Catalin Marinasb87324d2009-07-07 10:32:58 +01001478 return seq_release(inode, file);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001479}
1480
Catalin Marinas189d84e2009-08-27 14:29:15 +01001481static int dump_str_object_info(const char *str)
1482{
1483 unsigned long flags;
1484 struct kmemleak_object *object;
1485 unsigned long addr;
1486
1487 addr= simple_strtoul(str, NULL, 0);
1488 object = find_and_get_object(addr, 0);
1489 if (!object) {
1490 pr_info("Unknown object at 0x%08lx\n", addr);
1491 return -EINVAL;
1492 }
1493
1494 spin_lock_irqsave(&object->lock, flags);
1495 dump_object_info(object);
1496 spin_unlock_irqrestore(&object->lock, flags);
1497
1498 put_object(object);
1499 return 0;
1500}
1501
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001502/*
Luis R. Rodriguez30b37102009-09-04 17:44:51 -07001503 * We use grey instead of black to ensure we can do future scans on the same
1504 * objects. If we did not do future scans these black objects could
1505 * potentially contain references to newly allocated objects in the future and
1506 * we'd end up with false positives.
1507 */
1508static void kmemleak_clear(void)
1509{
1510 struct kmemleak_object *object;
1511 unsigned long flags;
1512
1513 rcu_read_lock();
1514 list_for_each_entry_rcu(object, &object_list, object_list) {
1515 spin_lock_irqsave(&object->lock, flags);
1516 if ((object->flags & OBJECT_REPORTED) &&
1517 unreferenced_object(object))
Luis R. Rodrigueza1084c82009-09-04 17:44:52 -07001518 __paint_it(object, KMEMLEAK_GREY);
Luis R. Rodriguez30b37102009-09-04 17:44:51 -07001519 spin_unlock_irqrestore(&object->lock, flags);
1520 }
1521 rcu_read_unlock();
1522}
1523
1524/*
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001525 * File write operation to configure kmemleak at run-time. The following
1526 * commands can be written to the /sys/kernel/debug/kmemleak file:
1527 * off - disable kmemleak (irreversible)
1528 * stack=on - enable the task stacks scanning
1529 * stack=off - disable the tasks stacks scanning
1530 * scan=on - start the automatic memory scanning thread
1531 * scan=off - stop the automatic memory scanning thread
1532 * scan=... - set the automatic memory scanning period in seconds (0 to
1533 * disable it)
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001534 * scan - trigger a memory scan
Luis R. Rodriguez30b37102009-09-04 17:44:51 -07001535 * clear - mark all current reported unreferenced kmemleak objects as
1536 * grey to ignore printing them
Catalin Marinas189d84e2009-08-27 14:29:15 +01001537 * dump=... - dump information about the object found at the given address
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001538 */
1539static ssize_t kmemleak_write(struct file *file, const char __user *user_buf,
1540 size_t size, loff_t *ppos)
1541{
1542 char buf[64];
1543 int buf_size;
Catalin Marinasb87324d2009-07-07 10:32:58 +01001544 int ret;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001545
1546 buf_size = min(size, (sizeof(buf) - 1));
1547 if (strncpy_from_user(buf, user_buf, buf_size) < 0)
1548 return -EFAULT;
1549 buf[buf_size] = 0;
1550
Catalin Marinasb87324d2009-07-07 10:32:58 +01001551 ret = mutex_lock_interruptible(&scan_mutex);
1552 if (ret < 0)
1553 return ret;
1554
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001555 if (strncmp(buf, "off", 3) == 0)
1556 kmemleak_disable();
1557 else if (strncmp(buf, "stack=on", 8) == 0)
1558 kmemleak_stack_scan = 1;
1559 else if (strncmp(buf, "stack=off", 9) == 0)
1560 kmemleak_stack_scan = 0;
1561 else if (strncmp(buf, "scan=on", 7) == 0)
1562 start_scan_thread();
1563 else if (strncmp(buf, "scan=off", 8) == 0)
1564 stop_scan_thread();
1565 else if (strncmp(buf, "scan=", 5) == 0) {
1566 unsigned long secs;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001567
Catalin Marinasb87324d2009-07-07 10:32:58 +01001568 ret = strict_strtoul(buf + 5, 0, &secs);
1569 if (ret < 0)
1570 goto out;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001571 stop_scan_thread();
1572 if (secs) {
1573 jiffies_scan_wait = msecs_to_jiffies(secs * 1000);
1574 start_scan_thread();
1575 }
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001576 } else if (strncmp(buf, "scan", 4) == 0)
1577 kmemleak_scan();
Luis R. Rodriguez30b37102009-09-04 17:44:51 -07001578 else if (strncmp(buf, "clear", 5) == 0)
1579 kmemleak_clear();
Catalin Marinas189d84e2009-08-27 14:29:15 +01001580 else if (strncmp(buf, "dump=", 5) == 0)
1581 ret = dump_str_object_info(buf + 5);
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001582 else
Catalin Marinasb87324d2009-07-07 10:32:58 +01001583 ret = -EINVAL;
1584
1585out:
1586 mutex_unlock(&scan_mutex);
1587 if (ret < 0)
1588 return ret;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001589
1590 /* ignore the rest of the buffer, only one command at a time */
1591 *ppos += size;
1592 return size;
1593}
1594
1595static const struct file_operations kmemleak_fops = {
1596 .owner = THIS_MODULE,
1597 .open = kmemleak_open,
1598 .read = seq_read,
1599 .write = kmemleak_write,
1600 .llseek = seq_lseek,
1601 .release = kmemleak_release,
1602};
1603
1604/*
1605 * Perform the freeing of the kmemleak internal objects after waiting for any
1606 * current memory scan to complete.
1607 */
Catalin Marinas179a8102009-09-07 10:14:42 +01001608static void kmemleak_do_cleanup(struct work_struct *work)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001609{
1610 struct kmemleak_object *object;
1611
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001612 mutex_lock(&scan_mutex);
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001613 stop_scan_thread();
1614
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001615 rcu_read_lock();
1616 list_for_each_entry_rcu(object, &object_list, object_list)
Catalin Marinas53238a62009-07-07 10:33:00 +01001617 delete_object_full(object->pointer);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001618 rcu_read_unlock();
1619 mutex_unlock(&scan_mutex);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001620}
1621
Catalin Marinas179a8102009-09-07 10:14:42 +01001622static DECLARE_WORK(cleanup_work, kmemleak_do_cleanup);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001623
1624/*
1625 * Disable kmemleak. No memory allocation/freeing will be traced once this
1626 * function is called. Disabling kmemleak is an irreversible operation.
1627 */
1628static void kmemleak_disable(void)
1629{
1630 /* atomically check whether it was already invoked */
1631 if (atomic_cmpxchg(&kmemleak_error, 0, 1))
1632 return;
1633
1634 /* stop any memory operation tracing */
1635 atomic_set(&kmemleak_early_log, 0);
1636 atomic_set(&kmemleak_enabled, 0);
1637
1638 /* check whether it is too early for a kernel thread */
1639 if (atomic_read(&kmemleak_initialized))
Catalin Marinas179a8102009-09-07 10:14:42 +01001640 schedule_work(&cleanup_work);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001641
1642 pr_info("Kernel memory leak detector disabled\n");
1643}
1644
1645/*
1646 * Allow boot-time kmemleak disabling (enabled by default).
1647 */
1648static int kmemleak_boot_config(char *str)
1649{
1650 if (!str)
1651 return -EINVAL;
1652 if (strcmp(str, "off") == 0)
1653 kmemleak_disable();
Jason Baronab0155a2010-07-19 11:54:17 +01001654 else if (strcmp(str, "on") == 0)
1655 kmemleak_skip_disable = 1;
1656 else
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001657 return -EINVAL;
1658 return 0;
1659}
1660early_param("kmemleak", kmemleak_boot_config);
1661
1662/*
Catalin Marinas20301172009-06-17 18:29:04 +01001663 * Kmemleak initialization.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001664 */
1665void __init kmemleak_init(void)
1666{
1667 int i;
1668 unsigned long flags;
1669
Jason Baronab0155a2010-07-19 11:54:17 +01001670#ifdef CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF
1671 if (!kmemleak_skip_disable) {
1672 kmemleak_disable();
1673 return;
1674 }
1675#endif
1676
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001677 jiffies_min_age = msecs_to_jiffies(MSECS_MIN_AGE);
1678 jiffies_scan_wait = msecs_to_jiffies(SECS_SCAN_WAIT * 1000);
1679
1680 object_cache = KMEM_CACHE(kmemleak_object, SLAB_NOLEAKTRACE);
1681 scan_area_cache = KMEM_CACHE(kmemleak_scan_area, SLAB_NOLEAKTRACE);
1682 INIT_PRIO_TREE_ROOT(&object_tree_root);
1683
1684 /* the kernel is still in UP mode, so disabling the IRQs is enough */
1685 local_irq_save(flags);
1686 if (!atomic_read(&kmemleak_error)) {
1687 atomic_set(&kmemleak_enabled, 1);
1688 atomic_set(&kmemleak_early_log, 0);
1689 }
1690 local_irq_restore(flags);
1691
1692 /*
1693 * This is the point where tracking allocations is safe. Automatic
1694 * scanning is started during the late initcall. Add the early logged
1695 * callbacks to the kmemleak infrastructure.
1696 */
1697 for (i = 0; i < crt_early_log; i++) {
1698 struct early_log *log = &early_log[i];
1699
1700 switch (log->op_type) {
1701 case KMEMLEAK_ALLOC:
Catalin Marinasfd678962009-08-27 14:29:17 +01001702 early_alloc(log);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001703 break;
1704 case KMEMLEAK_FREE:
1705 kmemleak_free(log->ptr);
1706 break;
Catalin Marinas53238a62009-07-07 10:33:00 +01001707 case KMEMLEAK_FREE_PART:
1708 kmemleak_free_part(log->ptr, log->size);
1709 break;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001710 case KMEMLEAK_NOT_LEAK:
1711 kmemleak_not_leak(log->ptr);
1712 break;
1713 case KMEMLEAK_IGNORE:
1714 kmemleak_ignore(log->ptr);
1715 break;
1716 case KMEMLEAK_SCAN_AREA:
Catalin Marinasc017b4b2009-10-28 13:33:09 +00001717 kmemleak_scan_area(log->ptr, log->size, GFP_KERNEL);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001718 break;
1719 case KMEMLEAK_NO_SCAN:
1720 kmemleak_no_scan(log->ptr);
1721 break;
1722 default:
1723 WARN_ON(1);
1724 }
1725 }
1726}
1727
1728/*
1729 * Late initialization function.
1730 */
1731static int __init kmemleak_late_init(void)
1732{
1733 struct dentry *dentry;
1734
1735 atomic_set(&kmemleak_initialized, 1);
1736
1737 if (atomic_read(&kmemleak_error)) {
1738 /*
Lucas De Marchi25985ed2011-03-30 22:57:33 -03001739 * Some error occurred and kmemleak was disabled. There is a
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001740 * small chance that kmemleak_disable() was called immediately
1741 * after setting kmemleak_initialized and we may end up with
1742 * two clean-up threads but serialized by scan_mutex.
1743 */
Catalin Marinas179a8102009-09-07 10:14:42 +01001744 schedule_work(&cleanup_work);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001745 return -ENOMEM;
1746 }
1747
1748 dentry = debugfs_create_file("kmemleak", S_IRUGO, NULL, NULL,
1749 &kmemleak_fops);
1750 if (!dentry)
Joe Perchesae281062009-06-23 14:40:26 +01001751 pr_warning("Failed to create the debugfs kmemleak file\n");
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001752 mutex_lock(&scan_mutex);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001753 start_scan_thread();
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001754 mutex_unlock(&scan_mutex);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001755
1756 pr_info("Kernel memory leak detector initialized\n");
1757
1758 return 0;
1759}
1760late_initcall(kmemleak_late_init);