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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 */
116#define GFP_KMEMLEAK_MASK (GFP_KERNEL | GFP_ATOMIC)
117
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100118/* scanning area inside a memory block */
119struct kmemleak_scan_area {
120 struct hlist_node node;
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000121 unsigned long start;
122 size_t size;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100123};
124
Luis R. Rodrigueza1084c82009-09-04 17:44:52 -0700125#define KMEMLEAK_GREY 0
126#define KMEMLEAK_BLACK -1
127
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100128/*
129 * Structure holding the metadata for each allocated memory block.
130 * Modifications to such objects should be made while holding the
131 * object->lock. Insertions or deletions from object_list, gray_list or
132 * tree_node are already protected by the corresponding locks or mutex (see
133 * the notes on locking above). These objects are reference-counted
134 * (use_count) and freed using the RCU mechanism.
135 */
136struct kmemleak_object {
137 spinlock_t lock;
138 unsigned long flags; /* object status flags */
139 struct list_head object_list;
140 struct list_head gray_list;
141 struct prio_tree_node tree_node;
142 struct rcu_head rcu; /* object_list lockless traversal */
143 /* object usage count; object freed when use_count == 0 */
144 atomic_t use_count;
145 unsigned long pointer;
146 size_t size;
147 /* minimum number of a pointers found before it is considered leak */
148 int min_count;
149 /* the total number of pointers found pointing to this object */
150 int count;
Catalin Marinas04609ccc2009-10-28 13:33:12 +0000151 /* checksum for detecting modified objects */
152 u32 checksum;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100153 /* memory ranges to be scanned inside an object (empty for all) */
154 struct hlist_head area_list;
155 unsigned long trace[MAX_TRACE];
156 unsigned int trace_len;
157 unsigned long jiffies; /* creation timestamp */
158 pid_t pid; /* pid of the current task */
159 char comm[TASK_COMM_LEN]; /* executable name */
160};
161
162/* flag representing the memory block allocation status */
163#define OBJECT_ALLOCATED (1 << 0)
164/* flag set after the first reporting of an unreference object */
165#define OBJECT_REPORTED (1 << 1)
166/* flag set to not scan the object */
167#define OBJECT_NO_SCAN (1 << 2)
168
Sergey Senozhatsky0494e082009-08-27 14:29:18 +0100169/* number of bytes to print per line; must be 16 or 32 */
170#define HEX_ROW_SIZE 16
171/* number of bytes to print at a time (1, 2, 4, 8) */
172#define HEX_GROUP_SIZE 1
173/* include ASCII after the hex output */
174#define HEX_ASCII 1
175/* max number of lines to be printed */
176#define HEX_MAX_LINES 2
177
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100178/* the list of all allocated objects */
179static LIST_HEAD(object_list);
180/* the list of gray-colored objects (see color_gray comment below) */
181static LIST_HEAD(gray_list);
182/* prio search tree for object boundaries */
183static struct prio_tree_root object_tree_root;
184/* rw_lock protecting the access to object_list and prio_tree_root */
185static DEFINE_RWLOCK(kmemleak_lock);
186
187/* allocation caches for kmemleak internal data */
188static struct kmem_cache *object_cache;
189static struct kmem_cache *scan_area_cache;
190
191/* set if tracing memory operations is enabled */
192static atomic_t kmemleak_enabled = ATOMIC_INIT(0);
193/* set in the late_initcall if there were no errors */
194static atomic_t kmemleak_initialized = ATOMIC_INIT(0);
195/* enables or disables early logging of the memory operations */
196static atomic_t kmemleak_early_log = ATOMIC_INIT(1);
197/* set if a fata kmemleak error has occurred */
198static atomic_t kmemleak_error = ATOMIC_INIT(0);
199
200/* minimum and maximum address that may be valid pointers */
201static unsigned long min_addr = ULONG_MAX;
202static unsigned long max_addr;
203
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100204static struct task_struct *scan_thread;
Catalin Marinasacf49682009-06-26 17:38:29 +0100205/* used to avoid reporting of recently allocated objects */
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100206static unsigned long jiffies_min_age;
Catalin Marinasacf49682009-06-26 17:38:29 +0100207static unsigned long jiffies_last_scan;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100208/* delay between automatic memory scannings */
209static signed long jiffies_scan_wait;
210/* enables or disables the task stacks scanning */
Catalin Marinase0a2a162009-06-26 17:38:25 +0100211static int kmemleak_stack_scan = 1;
Catalin Marinas4698c1f2009-06-26 17:38:27 +0100212/* protects the memory scanning, parameters and debug/kmemleak file access */
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100213static DEFINE_MUTEX(scan_mutex);
Jason Baronab0155a2010-07-19 11:54:17 +0100214/* setting kmemleak=on, will set this var, skipping the disable */
215static int kmemleak_skip_disable;
216
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100217
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100218/*
Catalin Marinas20301172009-06-17 18:29:04 +0100219 * Early object allocation/freeing logging. Kmemleak is initialized after the
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100220 * kernel allocator. However, both the kernel allocator and kmemleak may
Catalin Marinas20301172009-06-17 18:29:04 +0100221 * allocate memory blocks which need to be tracked. Kmemleak defines an
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100222 * arbitrary buffer to hold the allocation/freeing information before it is
223 * fully initialized.
224 */
225
226/* kmemleak operation type for early logging */
227enum {
228 KMEMLEAK_ALLOC,
229 KMEMLEAK_FREE,
Catalin Marinas53238a62009-07-07 10:33:00 +0100230 KMEMLEAK_FREE_PART,
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100231 KMEMLEAK_NOT_LEAK,
232 KMEMLEAK_IGNORE,
233 KMEMLEAK_SCAN_AREA,
234 KMEMLEAK_NO_SCAN
235};
236
237/*
238 * Structure holding the information passed to kmemleak callbacks during the
239 * early logging.
240 */
241struct early_log {
242 int op_type; /* kmemleak operation type */
243 const void *ptr; /* allocated/freed memory block */
244 size_t size; /* memory block size */
245 int min_count; /* minimum reference count */
Catalin Marinasfd678962009-08-27 14:29:17 +0100246 unsigned long trace[MAX_TRACE]; /* stack trace */
247 unsigned int trace_len; /* stack trace length */
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100248};
249
250/* early logging buffer and current position */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100251static struct early_log
252 early_log[CONFIG_DEBUG_KMEMLEAK_EARLY_LOG_SIZE] __initdata;
253static int crt_early_log __initdata;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100254
255static void kmemleak_disable(void);
256
257/*
258 * Print a warning and dump the stack trace.
259 */
260#define kmemleak_warn(x...) do { \
261 pr_warning(x); \
262 dump_stack(); \
263} while (0)
264
265/*
266 * Macro invoked when a serious kmemleak condition occured and cannot be
Catalin Marinas20301172009-06-17 18:29:04 +0100267 * recovered from. Kmemleak will be disabled and further allocation/freeing
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100268 * tracing no longer available.
269 */
Catalin Marinas000814f2009-06-17 18:29:03 +0100270#define kmemleak_stop(x...) do { \
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100271 kmemleak_warn(x); \
272 kmemleak_disable(); \
273} while (0)
274
275/*
Sergey Senozhatsky0494e082009-08-27 14:29:18 +0100276 * Printing of the objects hex dump to the seq file. The number of lines to be
277 * printed is limited to HEX_MAX_LINES to prevent seq file spamming. The
278 * actual number of printed bytes depends on HEX_ROW_SIZE. It must be called
279 * with the object->lock held.
280 */
281static void hex_dump_object(struct seq_file *seq,
282 struct kmemleak_object *object)
283{
284 const u8 *ptr = (const u8 *)object->pointer;
285 int i, len, remaining;
286 unsigned char linebuf[HEX_ROW_SIZE * 5];
287
288 /* limit the number of lines to HEX_MAX_LINES */
289 remaining = len =
290 min(object->size, (size_t)(HEX_MAX_LINES * HEX_ROW_SIZE));
291
292 seq_printf(seq, " hex dump (first %d bytes):\n", len);
293 for (i = 0; i < len; i += HEX_ROW_SIZE) {
294 int linelen = min(remaining, HEX_ROW_SIZE);
295
296 remaining -= HEX_ROW_SIZE;
297 hex_dump_to_buffer(ptr + i, linelen, HEX_ROW_SIZE,
298 HEX_GROUP_SIZE, linebuf, sizeof(linebuf),
299 HEX_ASCII);
300 seq_printf(seq, " %s\n", linebuf);
301 }
302}
303
304/*
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100305 * Object colors, encoded with count and min_count:
306 * - white - orphan object, not enough references to it (count < min_count)
307 * - gray - not orphan, not marked as false positive (min_count == 0) or
308 * sufficient references to it (count >= min_count)
309 * - black - ignore, it doesn't contain references (e.g. text section)
310 * (min_count == -1). No function defined for this color.
311 * Newly created objects don't have any color assigned (object->count == -1)
312 * before the next memory scan when they become white.
313 */
Luis R. Rodriguez4a558dd2009-09-08 16:34:50 +0100314static bool color_white(const struct kmemleak_object *object)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100315{
Luis R. Rodrigueza1084c82009-09-04 17:44:52 -0700316 return object->count != KMEMLEAK_BLACK &&
317 object->count < object->min_count;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100318}
319
Luis R. Rodriguez4a558dd2009-09-08 16:34:50 +0100320static bool color_gray(const struct kmemleak_object *object)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100321{
Luis R. Rodrigueza1084c82009-09-04 17:44:52 -0700322 return object->min_count != KMEMLEAK_BLACK &&
323 object->count >= object->min_count;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100324}
325
326/*
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100327 * Objects are considered unreferenced only if their color is white, they have
328 * not be deleted and have a minimum age to avoid false positives caused by
329 * pointers temporarily stored in CPU registers.
330 */
Luis R. Rodriguez4a558dd2009-09-08 16:34:50 +0100331static bool unreferenced_object(struct kmemleak_object *object)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100332{
Catalin Marinas04609ccc2009-10-28 13:33:12 +0000333 return (color_white(object) && object->flags & OBJECT_ALLOCATED) &&
Catalin Marinasacf49682009-06-26 17:38:29 +0100334 time_before_eq(object->jiffies + jiffies_min_age,
335 jiffies_last_scan);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100336}
337
338/*
Catalin Marinasbab4a342009-06-26 17:38:26 +0100339 * Printing of the unreferenced objects information to the seq file. The
340 * print_unreferenced function must be called with the object->lock held.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100341 */
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100342static void print_unreferenced(struct seq_file *seq,
343 struct kmemleak_object *object)
344{
345 int i;
Catalin Marinasfefdd332009-10-28 13:33:12 +0000346 unsigned int msecs_age = jiffies_to_msecs(jiffies - object->jiffies);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100347
Catalin Marinasbab4a342009-06-26 17:38:26 +0100348 seq_printf(seq, "unreferenced object 0x%08lx (size %zu):\n",
349 object->pointer, object->size);
Catalin Marinasfefdd332009-10-28 13:33:12 +0000350 seq_printf(seq, " comm \"%s\", pid %d, jiffies %lu (age %d.%03ds)\n",
351 object->comm, object->pid, object->jiffies,
352 msecs_age / 1000, msecs_age % 1000);
Sergey Senozhatsky0494e082009-08-27 14:29:18 +0100353 hex_dump_object(seq, object);
Catalin Marinasbab4a342009-06-26 17:38:26 +0100354 seq_printf(seq, " backtrace:\n");
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100355
356 for (i = 0; i < object->trace_len; i++) {
357 void *ptr = (void *)object->trace[i];
Catalin Marinasbab4a342009-06-26 17:38:26 +0100358 seq_printf(seq, " [<%p>] %pS\n", ptr, ptr);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100359 }
360}
361
362/*
363 * Print the kmemleak_object information. This function is used mainly for
364 * debugging special cases when kmemleak operations. It must be called with
365 * the object->lock held.
366 */
367static void dump_object_info(struct kmemleak_object *object)
368{
369 struct stack_trace trace;
370
371 trace.nr_entries = object->trace_len;
372 trace.entries = object->trace;
373
Joe Perchesae281062009-06-23 14:40:26 +0100374 pr_notice("Object 0x%08lx (size %zu):\n",
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100375 object->tree_node.start, object->size);
376 pr_notice(" comm \"%s\", pid %d, jiffies %lu\n",
377 object->comm, object->pid, object->jiffies);
378 pr_notice(" min_count = %d\n", object->min_count);
379 pr_notice(" count = %d\n", object->count);
Catalin Marinas189d84e2009-08-27 14:29:15 +0100380 pr_notice(" flags = 0x%lx\n", object->flags);
Catalin Marinas04609ccc2009-10-28 13:33:12 +0000381 pr_notice(" checksum = %d\n", object->checksum);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100382 pr_notice(" backtrace:\n");
383 print_stack_trace(&trace, 4);
384}
385
386/*
387 * Look-up a memory block metadata (kmemleak_object) in the priority search
388 * tree based on a pointer value. If alias is 0, only values pointing to the
389 * beginning of the memory block are allowed. The kmemleak_lock must be held
390 * when calling this function.
391 */
392static struct kmemleak_object *lookup_object(unsigned long ptr, int alias)
393{
394 struct prio_tree_node *node;
395 struct prio_tree_iter iter;
396 struct kmemleak_object *object;
397
398 prio_tree_iter_init(&iter, &object_tree_root, ptr, ptr);
399 node = prio_tree_next(&iter);
400 if (node) {
401 object = prio_tree_entry(node, struct kmemleak_object,
402 tree_node);
403 if (!alias && object->pointer != ptr) {
Catalin Marinasa7686a42010-07-19 11:54:16 +0100404 pr_warning("Found object by alias at 0x%08lx\n", ptr);
405 dump_stack();
406 dump_object_info(object);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100407 object = NULL;
408 }
409 } else
410 object = NULL;
411
412 return object;
413}
414
415/*
416 * Increment the object use_count. Return 1 if successful or 0 otherwise. Note
417 * that once an object's use_count reached 0, the RCU freeing was already
418 * registered and the object should no longer be used. This function must be
419 * called under the protection of rcu_read_lock().
420 */
421static int get_object(struct kmemleak_object *object)
422{
423 return atomic_inc_not_zero(&object->use_count);
424}
425
426/*
427 * RCU callback to free a kmemleak_object.
428 */
429static void free_object_rcu(struct rcu_head *rcu)
430{
431 struct hlist_node *elem, *tmp;
432 struct kmemleak_scan_area *area;
433 struct kmemleak_object *object =
434 container_of(rcu, struct kmemleak_object, rcu);
435
436 /*
437 * Once use_count is 0 (guaranteed by put_object), there is no other
438 * code accessing this object, hence no need for locking.
439 */
440 hlist_for_each_entry_safe(area, elem, tmp, &object->area_list, node) {
441 hlist_del(elem);
442 kmem_cache_free(scan_area_cache, area);
443 }
444 kmem_cache_free(object_cache, object);
445}
446
447/*
448 * Decrement the object use_count. Once the count is 0, free the object using
449 * an RCU callback. Since put_object() may be called via the kmemleak_free() ->
450 * delete_object() path, the delayed RCU freeing ensures that there is no
451 * recursive call to the kernel allocator. Lock-less RCU object_list traversal
452 * is also possible.
453 */
454static void put_object(struct kmemleak_object *object)
455{
456 if (!atomic_dec_and_test(&object->use_count))
457 return;
458
459 /* should only get here after delete_object was called */
460 WARN_ON(object->flags & OBJECT_ALLOCATED);
461
462 call_rcu(&object->rcu, free_object_rcu);
463}
464
465/*
466 * Look up an object in the prio search tree and increase its use_count.
467 */
468static struct kmemleak_object *find_and_get_object(unsigned long ptr, int alias)
469{
470 unsigned long flags;
471 struct kmemleak_object *object = NULL;
472
473 rcu_read_lock();
474 read_lock_irqsave(&kmemleak_lock, flags);
475 if (ptr >= min_addr && ptr < max_addr)
476 object = lookup_object(ptr, alias);
477 read_unlock_irqrestore(&kmemleak_lock, flags);
478
479 /* check whether the object is still available */
480 if (object && !get_object(object))
481 object = NULL;
482 rcu_read_unlock();
483
484 return object;
485}
486
487/*
Catalin Marinasfd678962009-08-27 14:29:17 +0100488 * Save stack trace to the given array of MAX_TRACE size.
489 */
490static int __save_stack_trace(unsigned long *trace)
491{
492 struct stack_trace stack_trace;
493
494 stack_trace.max_entries = MAX_TRACE;
495 stack_trace.nr_entries = 0;
496 stack_trace.entries = trace;
497 stack_trace.skip = 2;
498 save_stack_trace(&stack_trace);
499
500 return stack_trace.nr_entries;
501}
502
503/*
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100504 * Create the metadata (struct kmemleak_object) corresponding to an allocated
505 * memory block and add it to the object_list and object_tree_root.
506 */
Catalin Marinasfd678962009-08-27 14:29:17 +0100507static struct kmemleak_object *create_object(unsigned long ptr, size_t size,
508 int min_count, gfp_t gfp)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100509{
510 unsigned long flags;
511 struct kmemleak_object *object;
512 struct prio_tree_node *node;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100513
Catalin Marinas216c04b2009-06-17 18:29:02 +0100514 object = kmem_cache_alloc(object_cache, gfp & GFP_KMEMLEAK_MASK);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100515 if (!object) {
Joe Perchesae281062009-06-23 14:40:26 +0100516 kmemleak_stop("Cannot allocate a kmemleak_object structure\n");
Catalin Marinasfd678962009-08-27 14:29:17 +0100517 return NULL;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100518 }
519
520 INIT_LIST_HEAD(&object->object_list);
521 INIT_LIST_HEAD(&object->gray_list);
522 INIT_HLIST_HEAD(&object->area_list);
523 spin_lock_init(&object->lock);
524 atomic_set(&object->use_count, 1);
Catalin Marinas04609ccc2009-10-28 13:33:12 +0000525 object->flags = OBJECT_ALLOCATED;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100526 object->pointer = ptr;
527 object->size = size;
528 object->min_count = min_count;
Catalin Marinas04609ccc2009-10-28 13:33:12 +0000529 object->count = 0; /* white color initially */
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100530 object->jiffies = jiffies;
Catalin Marinas04609ccc2009-10-28 13:33:12 +0000531 object->checksum = 0;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100532
533 /* task information */
534 if (in_irq()) {
535 object->pid = 0;
536 strncpy(object->comm, "hardirq", sizeof(object->comm));
537 } else if (in_softirq()) {
538 object->pid = 0;
539 strncpy(object->comm, "softirq", sizeof(object->comm));
540 } else {
541 object->pid = current->pid;
542 /*
543 * There is a small chance of a race with set_task_comm(),
544 * however using get_task_comm() here may cause locking
545 * dependency issues with current->alloc_lock. In the worst
546 * case, the command line is not correct.
547 */
548 strncpy(object->comm, current->comm, sizeof(object->comm));
549 }
550
551 /* kernel backtrace */
Catalin Marinasfd678962009-08-27 14:29:17 +0100552 object->trace_len = __save_stack_trace(object->trace);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100553
554 INIT_PRIO_TREE_NODE(&object->tree_node);
555 object->tree_node.start = ptr;
556 object->tree_node.last = ptr + size - 1;
557
558 write_lock_irqsave(&kmemleak_lock, flags);
Luis R. Rodriguez0580a182009-09-08 17:32:34 +0100559
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100560 min_addr = min(min_addr, ptr);
561 max_addr = max(max_addr, ptr + size);
562 node = prio_tree_insert(&object_tree_root, &object->tree_node);
563 /*
564 * The code calling the kernel does not yet have the pointer to the
565 * memory block to be able to free it. However, we still hold the
566 * kmemleak_lock here in case parts of the kernel started freeing
567 * random memory blocks.
568 */
569 if (node != &object->tree_node) {
Joe Perchesae281062009-06-23 14:40:26 +0100570 kmemleak_stop("Cannot insert 0x%lx into the object search tree "
571 "(already existing)\n", ptr);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100572 object = lookup_object(ptr, 1);
Luis R. Rodriguez0580a182009-09-08 17:32:34 +0100573 spin_lock(&object->lock);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100574 dump_object_info(object);
Luis R. Rodriguez0580a182009-09-08 17:32:34 +0100575 spin_unlock(&object->lock);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100576
577 goto out;
578 }
579 list_add_tail_rcu(&object->object_list, &object_list);
580out:
581 write_unlock_irqrestore(&kmemleak_lock, flags);
Catalin Marinasfd678962009-08-27 14:29:17 +0100582 return object;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100583}
584
585/*
586 * Remove the metadata (struct kmemleak_object) for a memory block from the
587 * object_list and object_tree_root and decrement its use_count.
588 */
Catalin Marinas53238a62009-07-07 10:33:00 +0100589static void __delete_object(struct kmemleak_object *object)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100590{
591 unsigned long flags;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100592
593 write_lock_irqsave(&kmemleak_lock, flags);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100594 prio_tree_remove(&object_tree_root, &object->tree_node);
595 list_del_rcu(&object->object_list);
596 write_unlock_irqrestore(&kmemleak_lock, flags);
597
598 WARN_ON(!(object->flags & OBJECT_ALLOCATED));
Catalin Marinas53238a62009-07-07 10:33:00 +0100599 WARN_ON(atomic_read(&object->use_count) < 2);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100600
601 /*
602 * Locking here also ensures that the corresponding memory block
603 * cannot be freed when it is being scanned.
604 */
605 spin_lock_irqsave(&object->lock, flags);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100606 object->flags &= ~OBJECT_ALLOCATED;
607 spin_unlock_irqrestore(&object->lock, flags);
608 put_object(object);
609}
610
611/*
Catalin Marinas53238a62009-07-07 10:33:00 +0100612 * Look up the metadata (struct kmemleak_object) corresponding to ptr and
613 * delete it.
614 */
615static void delete_object_full(unsigned long ptr)
616{
617 struct kmemleak_object *object;
618
619 object = find_and_get_object(ptr, 0);
620 if (!object) {
621#ifdef DEBUG
622 kmemleak_warn("Freeing unknown object at 0x%08lx\n",
623 ptr);
624#endif
625 return;
626 }
627 __delete_object(object);
628 put_object(object);
629}
630
631/*
632 * Look up the metadata (struct kmemleak_object) corresponding to ptr and
633 * delete it. If the memory block is partially freed, the function may create
634 * additional metadata for the remaining parts of the block.
635 */
636static void delete_object_part(unsigned long ptr, size_t size)
637{
638 struct kmemleak_object *object;
639 unsigned long start, end;
640
641 object = find_and_get_object(ptr, 1);
642 if (!object) {
643#ifdef DEBUG
644 kmemleak_warn("Partially freeing unknown object at 0x%08lx "
645 "(size %zu)\n", ptr, size);
646#endif
647 return;
648 }
649 __delete_object(object);
650
651 /*
652 * Create one or two objects that may result from the memory block
653 * split. Note that partial freeing is only done by free_bootmem() and
654 * this happens before kmemleak_init() is called. The path below is
655 * only executed during early log recording in kmemleak_init(), so
656 * GFP_KERNEL is enough.
657 */
658 start = object->pointer;
659 end = object->pointer + object->size;
660 if (ptr > start)
661 create_object(start, ptr - start, object->min_count,
662 GFP_KERNEL);
663 if (ptr + size < end)
664 create_object(ptr + size, end - ptr - size, object->min_count,
665 GFP_KERNEL);
666
667 put_object(object);
668}
Luis R. Rodrigueza1084c82009-09-04 17:44:52 -0700669
670static void __paint_it(struct kmemleak_object *object, int color)
671{
672 object->min_count = color;
673 if (color == KMEMLEAK_BLACK)
674 object->flags |= OBJECT_NO_SCAN;
675}
676
677static void paint_it(struct kmemleak_object *object, int color)
678{
679 unsigned long flags;
680
681 spin_lock_irqsave(&object->lock, flags);
682 __paint_it(object, color);
683 spin_unlock_irqrestore(&object->lock, flags);
684}
685
686static void paint_ptr(unsigned long ptr, int color)
687{
688 struct kmemleak_object *object;
689
690 object = find_and_get_object(ptr, 0);
691 if (!object) {
692 kmemleak_warn("Trying to color unknown object "
693 "at 0x%08lx as %s\n", ptr,
694 (color == KMEMLEAK_GREY) ? "Grey" :
695 (color == KMEMLEAK_BLACK) ? "Black" : "Unknown");
696 return;
697 }
698 paint_it(object, color);
699 put_object(object);
700}
701
Catalin Marinas53238a62009-07-07 10:33:00 +0100702/*
Holger Hans Peter Freyther145b64b2010-07-22 19:54:13 +0800703 * Mark an object permanently as gray-colored so that it can no longer be
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100704 * reported as a leak. This is used in general to mark a false positive.
705 */
706static void make_gray_object(unsigned long ptr)
707{
Luis R. Rodrigueza1084c82009-09-04 17:44:52 -0700708 paint_ptr(ptr, KMEMLEAK_GREY);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100709}
710
711/*
712 * Mark the object as black-colored so that it is ignored from scans and
713 * reporting.
714 */
715static void make_black_object(unsigned long ptr)
716{
Luis R. Rodrigueza1084c82009-09-04 17:44:52 -0700717 paint_ptr(ptr, KMEMLEAK_BLACK);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100718}
719
720/*
721 * Add a scanning area to the object. If at least one such area is added,
722 * kmemleak will only scan these ranges rather than the whole memory block.
723 */
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000724static void add_scan_area(unsigned long ptr, size_t size, gfp_t gfp)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100725{
726 unsigned long flags;
727 struct kmemleak_object *object;
728 struct kmemleak_scan_area *area;
729
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000730 object = find_and_get_object(ptr, 1);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100731 if (!object) {
Joe Perchesae281062009-06-23 14:40:26 +0100732 kmemleak_warn("Adding scan area to unknown object at 0x%08lx\n",
733 ptr);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100734 return;
735 }
736
Catalin Marinas216c04b2009-06-17 18:29:02 +0100737 area = kmem_cache_alloc(scan_area_cache, gfp & GFP_KMEMLEAK_MASK);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100738 if (!area) {
Joe Perchesae281062009-06-23 14:40:26 +0100739 kmemleak_warn("Cannot allocate a scan area\n");
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100740 goto out;
741 }
742
743 spin_lock_irqsave(&object->lock, flags);
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000744 if (ptr + size > object->pointer + object->size) {
Joe Perchesae281062009-06-23 14:40:26 +0100745 kmemleak_warn("Scan area larger than object 0x%08lx\n", ptr);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100746 dump_object_info(object);
747 kmem_cache_free(scan_area_cache, area);
748 goto out_unlock;
749 }
750
751 INIT_HLIST_NODE(&area->node);
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000752 area->start = ptr;
753 area->size = size;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100754
755 hlist_add_head(&area->node, &object->area_list);
756out_unlock:
757 spin_unlock_irqrestore(&object->lock, flags);
758out:
759 put_object(object);
760}
761
762/*
763 * Set the OBJECT_NO_SCAN flag for the object corresponding to the give
764 * pointer. Such object will not be scanned by kmemleak but references to it
765 * are searched.
766 */
767static void object_no_scan(unsigned long ptr)
768{
769 unsigned long flags;
770 struct kmemleak_object *object;
771
772 object = find_and_get_object(ptr, 0);
773 if (!object) {
Joe Perchesae281062009-06-23 14:40:26 +0100774 kmemleak_warn("Not scanning unknown object at 0x%08lx\n", ptr);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100775 return;
776 }
777
778 spin_lock_irqsave(&object->lock, flags);
779 object->flags |= OBJECT_NO_SCAN;
780 spin_unlock_irqrestore(&object->lock, flags);
781 put_object(object);
782}
783
784/*
785 * Log an early kmemleak_* call to the early_log buffer. These calls will be
786 * processed later once kmemleak is fully initialized.
787 */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100788static void __init log_early(int op_type, const void *ptr, size_t size,
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000789 int min_count)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100790{
791 unsigned long flags;
792 struct early_log *log;
793
794 if (crt_early_log >= ARRAY_SIZE(early_log)) {
Catalin Marinasaddd72c2009-09-11 10:42:09 +0100795 pr_warning("Early log buffer exceeded, "
796 "please increase DEBUG_KMEMLEAK_EARLY_LOG_SIZE\n");
Catalin Marinasa9d90582009-06-25 10:16:11 +0100797 kmemleak_disable();
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100798 return;
799 }
800
801 /*
802 * There is no need for locking since the kernel is still in UP mode
803 * at this stage. Disabling the IRQs is enough.
804 */
805 local_irq_save(flags);
806 log = &early_log[crt_early_log];
807 log->op_type = op_type;
808 log->ptr = ptr;
809 log->size = size;
810 log->min_count = min_count;
Catalin Marinasfd678962009-08-27 14:29:17 +0100811 if (op_type == KMEMLEAK_ALLOC)
812 log->trace_len = __save_stack_trace(log->trace);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100813 crt_early_log++;
814 local_irq_restore(flags);
815}
816
817/*
Catalin Marinasfd678962009-08-27 14:29:17 +0100818 * Log an early allocated block and populate the stack trace.
819 */
820static void early_alloc(struct early_log *log)
821{
822 struct kmemleak_object *object;
823 unsigned long flags;
824 int i;
825
826 if (!atomic_read(&kmemleak_enabled) || !log->ptr || IS_ERR(log->ptr))
827 return;
828
829 /*
830 * RCU locking needed to ensure object is not freed via put_object().
831 */
832 rcu_read_lock();
833 object = create_object((unsigned long)log->ptr, log->size,
Tetsuo Handac1bcd6b2009-10-09 10:39:24 +0100834 log->min_count, GFP_ATOMIC);
Catalin Marinas0d5d1aa2009-10-09 10:30:34 +0100835 if (!object)
836 goto out;
Catalin Marinasfd678962009-08-27 14:29:17 +0100837 spin_lock_irqsave(&object->lock, flags);
838 for (i = 0; i < log->trace_len; i++)
839 object->trace[i] = log->trace[i];
840 object->trace_len = log->trace_len;
841 spin_unlock_irqrestore(&object->lock, flags);
Catalin Marinas0d5d1aa2009-10-09 10:30:34 +0100842out:
Catalin Marinasfd678962009-08-27 14:29:17 +0100843 rcu_read_unlock();
844}
845
Catalin Marinasa2b6bf62010-07-19 11:54:17 +0100846/**
847 * kmemleak_alloc - register a newly allocated object
848 * @ptr: pointer to beginning of the object
849 * @size: size of the object
850 * @min_count: minimum number of references to this object. If during memory
851 * scanning a number of references less than @min_count is found,
852 * the object is reported as a memory leak. If @min_count is 0,
853 * the object is never reported as a leak. If @min_count is -1,
854 * the object is ignored (not scanned and not reported as a leak)
855 * @gfp: kmalloc() flags used for kmemleak internal memory allocations
856 *
857 * This function is called from the kernel allocators when a new object
858 * (memory block) is allocated (kmem_cache_alloc, kmalloc, vmalloc etc.).
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100859 */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100860void __ref kmemleak_alloc(const void *ptr, size_t size, int min_count,
861 gfp_t gfp)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100862{
863 pr_debug("%s(0x%p, %zu, %d)\n", __func__, ptr, size, min_count);
864
865 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
866 create_object((unsigned long)ptr, size, min_count, gfp);
867 else if (atomic_read(&kmemleak_early_log))
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000868 log_early(KMEMLEAK_ALLOC, ptr, size, min_count);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100869}
870EXPORT_SYMBOL_GPL(kmemleak_alloc);
871
Catalin Marinasa2b6bf62010-07-19 11:54:17 +0100872/**
873 * kmemleak_free - unregister a previously registered object
874 * @ptr: pointer to beginning of the object
875 *
876 * This function is called from the kernel allocators when an object (memory
877 * block) is freed (kmem_cache_free, kfree, vfree etc.).
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100878 */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100879void __ref kmemleak_free(const void *ptr)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100880{
881 pr_debug("%s(0x%p)\n", __func__, ptr);
882
883 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
Catalin Marinas53238a62009-07-07 10:33:00 +0100884 delete_object_full((unsigned long)ptr);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100885 else if (atomic_read(&kmemleak_early_log))
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000886 log_early(KMEMLEAK_FREE, ptr, 0, 0);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100887}
888EXPORT_SYMBOL_GPL(kmemleak_free);
889
Catalin Marinasa2b6bf62010-07-19 11:54:17 +0100890/**
891 * kmemleak_free_part - partially unregister a previously registered object
892 * @ptr: pointer to the beginning or inside the object. This also
893 * represents the start of the range to be freed
894 * @size: size to be unregistered
895 *
896 * This function is called when only a part of a memory block is freed
897 * (usually from the bootmem allocator).
Catalin Marinas53238a62009-07-07 10:33:00 +0100898 */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100899void __ref kmemleak_free_part(const void *ptr, size_t size)
Catalin Marinas53238a62009-07-07 10:33:00 +0100900{
901 pr_debug("%s(0x%p)\n", __func__, ptr);
902
903 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
904 delete_object_part((unsigned long)ptr, size);
905 else if (atomic_read(&kmemleak_early_log))
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000906 log_early(KMEMLEAK_FREE_PART, ptr, size, 0);
Catalin Marinas53238a62009-07-07 10:33:00 +0100907}
908EXPORT_SYMBOL_GPL(kmemleak_free_part);
909
Catalin Marinasa2b6bf62010-07-19 11:54:17 +0100910/**
911 * kmemleak_not_leak - mark an allocated object as false positive
912 * @ptr: pointer to beginning of the object
913 *
914 * Calling this function on an object will cause the memory block to no longer
915 * be reported as leak and always be scanned.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100916 */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100917void __ref kmemleak_not_leak(const void *ptr)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100918{
919 pr_debug("%s(0x%p)\n", __func__, ptr);
920
921 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
922 make_gray_object((unsigned long)ptr);
923 else if (atomic_read(&kmemleak_early_log))
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000924 log_early(KMEMLEAK_NOT_LEAK, ptr, 0, 0);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100925}
926EXPORT_SYMBOL(kmemleak_not_leak);
927
Catalin Marinasa2b6bf62010-07-19 11:54:17 +0100928/**
929 * kmemleak_ignore - ignore an allocated object
930 * @ptr: pointer to beginning of the object
931 *
932 * Calling this function on an object will cause the memory block to be
933 * ignored (not scanned and not reported as a leak). This is usually done when
934 * it is known that the corresponding block is not a leak and does not contain
935 * any references to other allocated memory blocks.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100936 */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100937void __ref kmemleak_ignore(const void *ptr)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100938{
939 pr_debug("%s(0x%p)\n", __func__, ptr);
940
941 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
942 make_black_object((unsigned long)ptr);
943 else if (atomic_read(&kmemleak_early_log))
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000944 log_early(KMEMLEAK_IGNORE, ptr, 0, 0);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100945}
946EXPORT_SYMBOL(kmemleak_ignore);
947
Catalin Marinasa2b6bf62010-07-19 11:54:17 +0100948/**
949 * kmemleak_scan_area - limit the range to be scanned in an allocated object
950 * @ptr: pointer to beginning or inside the object. This also
951 * represents the start of the scan area
952 * @size: size of the scan area
953 * @gfp: kmalloc() flags used for kmemleak internal memory allocations
954 *
955 * This function is used when it is known that only certain parts of an object
956 * contain references to other objects. Kmemleak will only scan these areas
957 * reducing the number false negatives.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100958 */
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000959void __ref kmemleak_scan_area(const void *ptr, size_t size, gfp_t gfp)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100960{
961 pr_debug("%s(0x%p)\n", __func__, ptr);
962
963 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000964 add_scan_area((unsigned long)ptr, size, gfp);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100965 else if (atomic_read(&kmemleak_early_log))
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000966 log_early(KMEMLEAK_SCAN_AREA, ptr, size, 0);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100967}
968EXPORT_SYMBOL(kmemleak_scan_area);
969
Catalin Marinasa2b6bf62010-07-19 11:54:17 +0100970/**
971 * kmemleak_no_scan - do not scan an allocated object
972 * @ptr: pointer to beginning of the object
973 *
974 * This function notifies kmemleak not to scan the given memory block. Useful
975 * in situations where it is known that the given object does not contain any
976 * references to other objects. Kmemleak will not scan such objects reducing
977 * the number of false negatives.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100978 */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100979void __ref kmemleak_no_scan(const void *ptr)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100980{
981 pr_debug("%s(0x%p)\n", __func__, ptr);
982
983 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
984 object_no_scan((unsigned long)ptr);
985 else if (atomic_read(&kmemleak_early_log))
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000986 log_early(KMEMLEAK_NO_SCAN, ptr, 0, 0);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100987}
988EXPORT_SYMBOL(kmemleak_no_scan);
989
990/*
Catalin Marinas04609ccc2009-10-28 13:33:12 +0000991 * Update an object's checksum and return true if it was modified.
992 */
993static bool update_checksum(struct kmemleak_object *object)
994{
995 u32 old_csum = object->checksum;
996
997 if (!kmemcheck_is_obj_initialized(object->pointer, object->size))
998 return false;
999
1000 object->checksum = crc32(0, (void *)object->pointer, object->size);
1001 return object->checksum != old_csum;
1002}
1003
1004/*
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001005 * Memory scanning is a long process and it needs to be interruptable. This
1006 * function checks whether such interrupt condition occured.
1007 */
1008static int scan_should_stop(void)
1009{
1010 if (!atomic_read(&kmemleak_enabled))
1011 return 1;
1012
1013 /*
1014 * This function may be called from either process or kthread context,
1015 * hence the need to check for both stop conditions.
1016 */
1017 if (current->mm)
1018 return signal_pending(current);
1019 else
1020 return kthread_should_stop();
1021
1022 return 0;
1023}
1024
1025/*
1026 * Scan a memory block (exclusive range) for valid pointers and add those
1027 * found to the gray list.
1028 */
1029static void scan_block(void *_start, void *_end,
Catalin Marinas4b8a9672009-07-07 10:32:56 +01001030 struct kmemleak_object *scanned, int allow_resched)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001031{
1032 unsigned long *ptr;
1033 unsigned long *start = PTR_ALIGN(_start, BYTES_PER_POINTER);
1034 unsigned long *end = _end - (BYTES_PER_POINTER - 1);
1035
1036 for (ptr = start; ptr < end; ptr++) {
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001037 struct kmemleak_object *object;
Pekka Enberg8e019362009-08-27 14:50:00 +01001038 unsigned long flags;
1039 unsigned long pointer;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001040
Catalin Marinas4b8a9672009-07-07 10:32:56 +01001041 if (allow_resched)
1042 cond_resched();
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001043 if (scan_should_stop())
1044 break;
1045
Pekka Enberg8e019362009-08-27 14:50:00 +01001046 /* don't scan uninitialized memory */
1047 if (!kmemcheck_is_obj_initialized((unsigned long)ptr,
1048 BYTES_PER_POINTER))
1049 continue;
1050
1051 pointer = *ptr;
1052
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001053 object = find_and_get_object(pointer, 1);
1054 if (!object)
1055 continue;
1056 if (object == scanned) {
1057 /* self referenced, ignore */
1058 put_object(object);
1059 continue;
1060 }
1061
1062 /*
1063 * Avoid the lockdep recursive warning on object->lock being
1064 * previously acquired in scan_object(). These locks are
1065 * enclosed by scan_mutex.
1066 */
1067 spin_lock_irqsave_nested(&object->lock, flags,
1068 SINGLE_DEPTH_NESTING);
1069 if (!color_white(object)) {
1070 /* non-orphan, ignored or new */
1071 spin_unlock_irqrestore(&object->lock, flags);
1072 put_object(object);
1073 continue;
1074 }
1075
1076 /*
1077 * Increase the object's reference count (number of pointers
1078 * to the memory block). If this count reaches the required
1079 * minimum, the object's color will become gray and it will be
1080 * added to the gray_list.
1081 */
1082 object->count++;
Catalin Marinas0587da42009-10-28 13:33:11 +00001083 if (color_gray(object)) {
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001084 list_add_tail(&object->gray_list, &gray_list);
Catalin Marinas0587da42009-10-28 13:33:11 +00001085 spin_unlock_irqrestore(&object->lock, flags);
1086 continue;
1087 }
1088
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001089 spin_unlock_irqrestore(&object->lock, flags);
Catalin Marinas0587da42009-10-28 13:33:11 +00001090 put_object(object);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001091 }
1092}
1093
1094/*
1095 * Scan a memory block corresponding to a kmemleak_object. A condition is
1096 * that object->use_count >= 1.
1097 */
1098static void scan_object(struct kmemleak_object *object)
1099{
1100 struct kmemleak_scan_area *area;
1101 struct hlist_node *elem;
1102 unsigned long flags;
1103
1104 /*
Uwe Kleine-König21ae2952009-10-07 15:21:09 +02001105 * Once the object->lock is acquired, the corresponding memory block
1106 * cannot be freed (the same lock is acquired in delete_object).
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001107 */
1108 spin_lock_irqsave(&object->lock, flags);
1109 if (object->flags & OBJECT_NO_SCAN)
1110 goto out;
1111 if (!(object->flags & OBJECT_ALLOCATED))
1112 /* already freed object */
1113 goto out;
Catalin Marinasaf986032009-08-27 14:29:12 +01001114 if (hlist_empty(&object->area_list)) {
1115 void *start = (void *)object->pointer;
1116 void *end = (void *)(object->pointer + object->size);
1117
1118 while (start < end && (object->flags & OBJECT_ALLOCATED) &&
1119 !(object->flags & OBJECT_NO_SCAN)) {
1120 scan_block(start, min(start + MAX_SCAN_SIZE, end),
1121 object, 0);
1122 start += MAX_SCAN_SIZE;
1123
1124 spin_unlock_irqrestore(&object->lock, flags);
1125 cond_resched();
1126 spin_lock_irqsave(&object->lock, flags);
1127 }
1128 } else
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001129 hlist_for_each_entry(area, elem, &object->area_list, node)
Catalin Marinasc017b4b2009-10-28 13:33:09 +00001130 scan_block((void *)area->start,
1131 (void *)(area->start + area->size),
1132 object, 0);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001133out:
1134 spin_unlock_irqrestore(&object->lock, flags);
1135}
1136
1137/*
Catalin Marinas04609ccc2009-10-28 13:33:12 +00001138 * Scan the objects already referenced (gray objects). More objects will be
1139 * referenced and, if there are no memory leaks, all the objects are scanned.
1140 */
1141static void scan_gray_list(void)
1142{
1143 struct kmemleak_object *object, *tmp;
1144
1145 /*
1146 * The list traversal is safe for both tail additions and removals
1147 * from inside the loop. The kmemleak objects cannot be freed from
1148 * outside the loop because their use_count was incremented.
1149 */
1150 object = list_entry(gray_list.next, typeof(*object), gray_list);
1151 while (&object->gray_list != &gray_list) {
1152 cond_resched();
1153
1154 /* may add new objects to the list */
1155 if (!scan_should_stop())
1156 scan_object(object);
1157
1158 tmp = list_entry(object->gray_list.next, typeof(*object),
1159 gray_list);
1160
1161 /* remove the object from the list and release it */
1162 list_del(&object->gray_list);
1163 put_object(object);
1164
1165 object = tmp;
1166 }
1167 WARN_ON(!list_empty(&gray_list));
1168}
1169
1170/*
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001171 * Scan data sections and all the referenced memory blocks allocated via the
1172 * kernel's standard allocators. This function must be called with the
1173 * scan_mutex held.
1174 */
1175static void kmemleak_scan(void)
1176{
1177 unsigned long flags;
Catalin Marinas04609ccc2009-10-28 13:33:12 +00001178 struct kmemleak_object *object;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001179 int i;
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001180 int new_leaks = 0;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001181
Catalin Marinasacf49682009-06-26 17:38:29 +01001182 jiffies_last_scan = jiffies;
1183
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001184 /* prepare the kmemleak_object's */
1185 rcu_read_lock();
1186 list_for_each_entry_rcu(object, &object_list, object_list) {
1187 spin_lock_irqsave(&object->lock, flags);
1188#ifdef DEBUG
1189 /*
1190 * With a few exceptions there should be a maximum of
1191 * 1 reference to any object at this point.
1192 */
1193 if (atomic_read(&object->use_count) > 1) {
Joe Perchesae281062009-06-23 14:40:26 +01001194 pr_debug("object->use_count = %d\n",
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001195 atomic_read(&object->use_count));
1196 dump_object_info(object);
1197 }
1198#endif
1199 /* reset the reference count (whiten the object) */
1200 object->count = 0;
1201 if (color_gray(object) && get_object(object))
1202 list_add_tail(&object->gray_list, &gray_list);
1203
1204 spin_unlock_irqrestore(&object->lock, flags);
1205 }
1206 rcu_read_unlock();
1207
1208 /* data/bss scanning */
Catalin Marinas4b8a9672009-07-07 10:32:56 +01001209 scan_block(_sdata, _edata, NULL, 1);
1210 scan_block(__bss_start, __bss_stop, NULL, 1);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001211
1212#ifdef CONFIG_SMP
1213 /* per-cpu sections scanning */
1214 for_each_possible_cpu(i)
1215 scan_block(__per_cpu_start + per_cpu_offset(i),
Catalin Marinas4b8a9672009-07-07 10:32:56 +01001216 __per_cpu_end + per_cpu_offset(i), NULL, 1);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001217#endif
1218
1219 /*
1220 * Struct page scanning for each node. The code below is not yet safe
1221 * with MEMORY_HOTPLUG.
1222 */
1223 for_each_online_node(i) {
1224 pg_data_t *pgdat = NODE_DATA(i);
1225 unsigned long start_pfn = pgdat->node_start_pfn;
1226 unsigned long end_pfn = start_pfn + pgdat->node_spanned_pages;
1227 unsigned long pfn;
1228
1229 for (pfn = start_pfn; pfn < end_pfn; pfn++) {
1230 struct page *page;
1231
1232 if (!pfn_valid(pfn))
1233 continue;
1234 page = pfn_to_page(pfn);
1235 /* only scan if page is in use */
1236 if (page_count(page) == 0)
1237 continue;
Catalin Marinas4b8a9672009-07-07 10:32:56 +01001238 scan_block(page, page + 1, NULL, 1);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001239 }
1240 }
1241
1242 /*
Catalin Marinas43ed5d62009-09-01 11:12:44 +01001243 * Scanning the task stacks (may introduce false negatives).
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001244 */
1245 if (kmemleak_stack_scan) {
Catalin Marinas43ed5d62009-09-01 11:12:44 +01001246 struct task_struct *p, *g;
1247
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001248 read_lock(&tasklist_lock);
Catalin Marinas43ed5d62009-09-01 11:12:44 +01001249 do_each_thread(g, p) {
1250 scan_block(task_stack_page(p), task_stack_page(p) +
1251 THREAD_SIZE, NULL, 0);
1252 } while_each_thread(g, p);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001253 read_unlock(&tasklist_lock);
1254 }
1255
1256 /*
1257 * Scan the objects already referenced from the sections scanned
Catalin Marinas04609ccc2009-10-28 13:33:12 +00001258 * above.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001259 */
Catalin Marinas04609ccc2009-10-28 13:33:12 +00001260 scan_gray_list();
Catalin Marinas25873622009-07-07 10:32:58 +01001261
1262 /*
Catalin Marinas04609ccc2009-10-28 13:33:12 +00001263 * Check for new or unreferenced objects modified since the previous
1264 * scan and color them gray until the next scan.
Catalin Marinas25873622009-07-07 10:32:58 +01001265 */
1266 rcu_read_lock();
1267 list_for_each_entry_rcu(object, &object_list, object_list) {
1268 spin_lock_irqsave(&object->lock, flags);
Catalin Marinas04609ccc2009-10-28 13:33:12 +00001269 if (color_white(object) && (object->flags & OBJECT_ALLOCATED)
1270 && update_checksum(object) && get_object(object)) {
1271 /* color it gray temporarily */
1272 object->count = object->min_count;
Catalin Marinas25873622009-07-07 10:32:58 +01001273 list_add_tail(&object->gray_list, &gray_list);
1274 }
1275 spin_unlock_irqrestore(&object->lock, flags);
1276 }
1277 rcu_read_unlock();
1278
Catalin Marinas04609ccc2009-10-28 13:33:12 +00001279 /*
1280 * Re-scan the gray list for modified unreferenced objects.
1281 */
1282 scan_gray_list();
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001283
1284 /*
Catalin Marinas04609ccc2009-10-28 13:33:12 +00001285 * If scanning was stopped do not report any new unreferenced objects.
Catalin Marinas17bb9e02009-06-29 17:13:56 +01001286 */
Catalin Marinas04609ccc2009-10-28 13:33:12 +00001287 if (scan_should_stop())
Catalin Marinas17bb9e02009-06-29 17:13:56 +01001288 return;
1289
1290 /*
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001291 * Scanning result reporting.
1292 */
1293 rcu_read_lock();
1294 list_for_each_entry_rcu(object, &object_list, object_list) {
1295 spin_lock_irqsave(&object->lock, flags);
1296 if (unreferenced_object(object) &&
1297 !(object->flags & OBJECT_REPORTED)) {
1298 object->flags |= OBJECT_REPORTED;
1299 new_leaks++;
1300 }
1301 spin_unlock_irqrestore(&object->lock, flags);
1302 }
1303 rcu_read_unlock();
1304
1305 if (new_leaks)
1306 pr_info("%d new suspected memory leaks (see "
1307 "/sys/kernel/debug/kmemleak)\n", new_leaks);
1308
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001309}
1310
1311/*
1312 * Thread function performing automatic memory scanning. Unreferenced objects
1313 * at the end of a memory scan are reported but only the first time.
1314 */
1315static int kmemleak_scan_thread(void *arg)
1316{
1317 static int first_run = 1;
1318
Joe Perchesae281062009-06-23 14:40:26 +01001319 pr_info("Automatic memory scanning thread started\n");
Catalin Marinasbf2a76b2009-07-07 10:32:55 +01001320 set_user_nice(current, 10);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001321
1322 /*
1323 * Wait before the first scan to allow the system to fully initialize.
1324 */
1325 if (first_run) {
1326 first_run = 0;
1327 ssleep(SECS_FIRST_SCAN);
1328 }
1329
1330 while (!kthread_should_stop()) {
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001331 signed long timeout = jiffies_scan_wait;
1332
1333 mutex_lock(&scan_mutex);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001334 kmemleak_scan();
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001335 mutex_unlock(&scan_mutex);
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001336
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001337 /* wait before the next scan */
1338 while (timeout && !kthread_should_stop())
1339 timeout = schedule_timeout_interruptible(timeout);
1340 }
1341
Joe Perchesae281062009-06-23 14:40:26 +01001342 pr_info("Automatic memory scanning thread ended\n");
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001343
1344 return 0;
1345}
1346
1347/*
1348 * Start the automatic memory scanning thread. This function must be called
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001349 * with the scan_mutex held.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001350 */
Luis R. Rodriguez7eb0d5e2009-09-08 17:31:45 +01001351static void start_scan_thread(void)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001352{
1353 if (scan_thread)
1354 return;
1355 scan_thread = kthread_run(kmemleak_scan_thread, NULL, "kmemleak");
1356 if (IS_ERR(scan_thread)) {
Joe Perchesae281062009-06-23 14:40:26 +01001357 pr_warning("Failed to create the scan thread\n");
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001358 scan_thread = NULL;
1359 }
1360}
1361
1362/*
1363 * Stop the automatic memory scanning thread. This function must be called
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001364 * with the scan_mutex held.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001365 */
Luis R. Rodriguez7eb0d5e2009-09-08 17:31:45 +01001366static void stop_scan_thread(void)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001367{
1368 if (scan_thread) {
1369 kthread_stop(scan_thread);
1370 scan_thread = NULL;
1371 }
1372}
1373
1374/*
1375 * Iterate over the object_list and return the first valid object at or after
1376 * the required position with its use_count incremented. The function triggers
1377 * a memory scanning when the pos argument points to the first position.
1378 */
1379static void *kmemleak_seq_start(struct seq_file *seq, loff_t *pos)
1380{
1381 struct kmemleak_object *object;
1382 loff_t n = *pos;
Catalin Marinasb87324d2009-07-07 10:32:58 +01001383 int err;
1384
1385 err = mutex_lock_interruptible(&scan_mutex);
1386 if (err < 0)
1387 return ERR_PTR(err);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001388
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001389 rcu_read_lock();
1390 list_for_each_entry_rcu(object, &object_list, object_list) {
1391 if (n-- > 0)
1392 continue;
1393 if (get_object(object))
1394 goto out;
1395 }
1396 object = NULL;
1397out:
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001398 return object;
1399}
1400
1401/*
1402 * Return the next object in the object_list. The function decrements the
1403 * use_count of the previous object and increases that of the next one.
1404 */
1405static void *kmemleak_seq_next(struct seq_file *seq, void *v, loff_t *pos)
1406{
1407 struct kmemleak_object *prev_obj = v;
1408 struct kmemleak_object *next_obj = NULL;
1409 struct list_head *n = &prev_obj->object_list;
1410
1411 ++(*pos);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001412
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001413 list_for_each_continue_rcu(n, &object_list) {
1414 next_obj = list_entry(n, struct kmemleak_object, object_list);
1415 if (get_object(next_obj))
1416 break;
1417 }
Catalin Marinas288c8572009-07-07 10:32:57 +01001418
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001419 put_object(prev_obj);
1420 return next_obj;
1421}
1422
1423/*
1424 * Decrement the use_count of the last object required, if any.
1425 */
1426static void kmemleak_seq_stop(struct seq_file *seq, void *v)
1427{
Catalin Marinasb87324d2009-07-07 10:32:58 +01001428 if (!IS_ERR(v)) {
1429 /*
1430 * kmemleak_seq_start may return ERR_PTR if the scan_mutex
1431 * waiting was interrupted, so only release it if !IS_ERR.
1432 */
Catalin Marinasf5886c72009-07-29 16:26:57 +01001433 rcu_read_unlock();
Catalin Marinasb87324d2009-07-07 10:32:58 +01001434 mutex_unlock(&scan_mutex);
1435 if (v)
1436 put_object(v);
1437 }
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001438}
1439
1440/*
1441 * Print the information for an unreferenced object to the seq file.
1442 */
1443static int kmemleak_seq_show(struct seq_file *seq, void *v)
1444{
1445 struct kmemleak_object *object = v;
1446 unsigned long flags;
1447
1448 spin_lock_irqsave(&object->lock, flags);
Catalin Marinas288c8572009-07-07 10:32:57 +01001449 if ((object->flags & OBJECT_REPORTED) && unreferenced_object(object))
Catalin Marinas17bb9e02009-06-29 17:13:56 +01001450 print_unreferenced(seq, object);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001451 spin_unlock_irqrestore(&object->lock, flags);
1452 return 0;
1453}
1454
1455static const struct seq_operations kmemleak_seq_ops = {
1456 .start = kmemleak_seq_start,
1457 .next = kmemleak_seq_next,
1458 .stop = kmemleak_seq_stop,
1459 .show = kmemleak_seq_show,
1460};
1461
1462static int kmemleak_open(struct inode *inode, struct file *file)
1463{
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001464 if (!atomic_read(&kmemleak_enabled))
1465 return -EBUSY;
1466
Catalin Marinasb87324d2009-07-07 10:32:58 +01001467 return seq_open(file, &kmemleak_seq_ops);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001468}
1469
1470static int kmemleak_release(struct inode *inode, struct file *file)
1471{
Catalin Marinasb87324d2009-07-07 10:32:58 +01001472 return seq_release(inode, file);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001473}
1474
Catalin Marinas189d84e2009-08-27 14:29:15 +01001475static int dump_str_object_info(const char *str)
1476{
1477 unsigned long flags;
1478 struct kmemleak_object *object;
1479 unsigned long addr;
1480
1481 addr= simple_strtoul(str, NULL, 0);
1482 object = find_and_get_object(addr, 0);
1483 if (!object) {
1484 pr_info("Unknown object at 0x%08lx\n", addr);
1485 return -EINVAL;
1486 }
1487
1488 spin_lock_irqsave(&object->lock, flags);
1489 dump_object_info(object);
1490 spin_unlock_irqrestore(&object->lock, flags);
1491
1492 put_object(object);
1493 return 0;
1494}
1495
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001496/*
Luis R. Rodriguez30b37102009-09-04 17:44:51 -07001497 * We use grey instead of black to ensure we can do future scans on the same
1498 * objects. If we did not do future scans these black objects could
1499 * potentially contain references to newly allocated objects in the future and
1500 * we'd end up with false positives.
1501 */
1502static void kmemleak_clear(void)
1503{
1504 struct kmemleak_object *object;
1505 unsigned long flags;
1506
1507 rcu_read_lock();
1508 list_for_each_entry_rcu(object, &object_list, object_list) {
1509 spin_lock_irqsave(&object->lock, flags);
1510 if ((object->flags & OBJECT_REPORTED) &&
1511 unreferenced_object(object))
Luis R. Rodrigueza1084c82009-09-04 17:44:52 -07001512 __paint_it(object, KMEMLEAK_GREY);
Luis R. Rodriguez30b37102009-09-04 17:44:51 -07001513 spin_unlock_irqrestore(&object->lock, flags);
1514 }
1515 rcu_read_unlock();
1516}
1517
1518/*
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001519 * File write operation to configure kmemleak at run-time. The following
1520 * commands can be written to the /sys/kernel/debug/kmemleak file:
1521 * off - disable kmemleak (irreversible)
1522 * stack=on - enable the task stacks scanning
1523 * stack=off - disable the tasks stacks scanning
1524 * scan=on - start the automatic memory scanning thread
1525 * scan=off - stop the automatic memory scanning thread
1526 * scan=... - set the automatic memory scanning period in seconds (0 to
1527 * disable it)
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001528 * scan - trigger a memory scan
Luis R. Rodriguez30b37102009-09-04 17:44:51 -07001529 * clear - mark all current reported unreferenced kmemleak objects as
1530 * grey to ignore printing them
Catalin Marinas189d84e2009-08-27 14:29:15 +01001531 * dump=... - dump information about the object found at the given address
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001532 */
1533static ssize_t kmemleak_write(struct file *file, const char __user *user_buf,
1534 size_t size, loff_t *ppos)
1535{
1536 char buf[64];
1537 int buf_size;
Catalin Marinasb87324d2009-07-07 10:32:58 +01001538 int ret;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001539
1540 buf_size = min(size, (sizeof(buf) - 1));
1541 if (strncpy_from_user(buf, user_buf, buf_size) < 0)
1542 return -EFAULT;
1543 buf[buf_size] = 0;
1544
Catalin Marinasb87324d2009-07-07 10:32:58 +01001545 ret = mutex_lock_interruptible(&scan_mutex);
1546 if (ret < 0)
1547 return ret;
1548
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001549 if (strncmp(buf, "off", 3) == 0)
1550 kmemleak_disable();
1551 else if (strncmp(buf, "stack=on", 8) == 0)
1552 kmemleak_stack_scan = 1;
1553 else if (strncmp(buf, "stack=off", 9) == 0)
1554 kmemleak_stack_scan = 0;
1555 else if (strncmp(buf, "scan=on", 7) == 0)
1556 start_scan_thread();
1557 else if (strncmp(buf, "scan=off", 8) == 0)
1558 stop_scan_thread();
1559 else if (strncmp(buf, "scan=", 5) == 0) {
1560 unsigned long secs;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001561
Catalin Marinasb87324d2009-07-07 10:32:58 +01001562 ret = strict_strtoul(buf + 5, 0, &secs);
1563 if (ret < 0)
1564 goto out;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001565 stop_scan_thread();
1566 if (secs) {
1567 jiffies_scan_wait = msecs_to_jiffies(secs * 1000);
1568 start_scan_thread();
1569 }
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001570 } else if (strncmp(buf, "scan", 4) == 0)
1571 kmemleak_scan();
Luis R. Rodriguez30b37102009-09-04 17:44:51 -07001572 else if (strncmp(buf, "clear", 5) == 0)
1573 kmemleak_clear();
Catalin Marinas189d84e2009-08-27 14:29:15 +01001574 else if (strncmp(buf, "dump=", 5) == 0)
1575 ret = dump_str_object_info(buf + 5);
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001576 else
Catalin Marinasb87324d2009-07-07 10:32:58 +01001577 ret = -EINVAL;
1578
1579out:
1580 mutex_unlock(&scan_mutex);
1581 if (ret < 0)
1582 return ret;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001583
1584 /* ignore the rest of the buffer, only one command at a time */
1585 *ppos += size;
1586 return size;
1587}
1588
1589static const struct file_operations kmemleak_fops = {
1590 .owner = THIS_MODULE,
1591 .open = kmemleak_open,
1592 .read = seq_read,
1593 .write = kmemleak_write,
1594 .llseek = seq_lseek,
1595 .release = kmemleak_release,
1596};
1597
1598/*
1599 * Perform the freeing of the kmemleak internal objects after waiting for any
1600 * current memory scan to complete.
1601 */
Catalin Marinas179a8102009-09-07 10:14:42 +01001602static void kmemleak_do_cleanup(struct work_struct *work)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001603{
1604 struct kmemleak_object *object;
1605
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001606 mutex_lock(&scan_mutex);
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001607 stop_scan_thread();
1608
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001609 rcu_read_lock();
1610 list_for_each_entry_rcu(object, &object_list, object_list)
Catalin Marinas53238a62009-07-07 10:33:00 +01001611 delete_object_full(object->pointer);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001612 rcu_read_unlock();
1613 mutex_unlock(&scan_mutex);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001614}
1615
Catalin Marinas179a8102009-09-07 10:14:42 +01001616static DECLARE_WORK(cleanup_work, kmemleak_do_cleanup);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001617
1618/*
1619 * Disable kmemleak. No memory allocation/freeing will be traced once this
1620 * function is called. Disabling kmemleak is an irreversible operation.
1621 */
1622static void kmemleak_disable(void)
1623{
1624 /* atomically check whether it was already invoked */
1625 if (atomic_cmpxchg(&kmemleak_error, 0, 1))
1626 return;
1627
1628 /* stop any memory operation tracing */
1629 atomic_set(&kmemleak_early_log, 0);
1630 atomic_set(&kmemleak_enabled, 0);
1631
1632 /* check whether it is too early for a kernel thread */
1633 if (atomic_read(&kmemleak_initialized))
Catalin Marinas179a8102009-09-07 10:14:42 +01001634 schedule_work(&cleanup_work);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001635
1636 pr_info("Kernel memory leak detector disabled\n");
1637}
1638
1639/*
1640 * Allow boot-time kmemleak disabling (enabled by default).
1641 */
1642static int kmemleak_boot_config(char *str)
1643{
1644 if (!str)
1645 return -EINVAL;
1646 if (strcmp(str, "off") == 0)
1647 kmemleak_disable();
Jason Baronab0155a2010-07-19 11:54:17 +01001648 else if (strcmp(str, "on") == 0)
1649 kmemleak_skip_disable = 1;
1650 else
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001651 return -EINVAL;
1652 return 0;
1653}
1654early_param("kmemleak", kmemleak_boot_config);
1655
1656/*
Catalin Marinas20301172009-06-17 18:29:04 +01001657 * Kmemleak initialization.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001658 */
1659void __init kmemleak_init(void)
1660{
1661 int i;
1662 unsigned long flags;
1663
Jason Baronab0155a2010-07-19 11:54:17 +01001664#ifdef CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF
1665 if (!kmemleak_skip_disable) {
1666 kmemleak_disable();
1667 return;
1668 }
1669#endif
1670
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001671 jiffies_min_age = msecs_to_jiffies(MSECS_MIN_AGE);
1672 jiffies_scan_wait = msecs_to_jiffies(SECS_SCAN_WAIT * 1000);
1673
1674 object_cache = KMEM_CACHE(kmemleak_object, SLAB_NOLEAKTRACE);
1675 scan_area_cache = KMEM_CACHE(kmemleak_scan_area, SLAB_NOLEAKTRACE);
1676 INIT_PRIO_TREE_ROOT(&object_tree_root);
1677
1678 /* the kernel is still in UP mode, so disabling the IRQs is enough */
1679 local_irq_save(flags);
1680 if (!atomic_read(&kmemleak_error)) {
1681 atomic_set(&kmemleak_enabled, 1);
1682 atomic_set(&kmemleak_early_log, 0);
1683 }
1684 local_irq_restore(flags);
1685
1686 /*
1687 * This is the point where tracking allocations is safe. Automatic
1688 * scanning is started during the late initcall. Add the early logged
1689 * callbacks to the kmemleak infrastructure.
1690 */
1691 for (i = 0; i < crt_early_log; i++) {
1692 struct early_log *log = &early_log[i];
1693
1694 switch (log->op_type) {
1695 case KMEMLEAK_ALLOC:
Catalin Marinasfd678962009-08-27 14:29:17 +01001696 early_alloc(log);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001697 break;
1698 case KMEMLEAK_FREE:
1699 kmemleak_free(log->ptr);
1700 break;
Catalin Marinas53238a62009-07-07 10:33:00 +01001701 case KMEMLEAK_FREE_PART:
1702 kmemleak_free_part(log->ptr, log->size);
1703 break;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001704 case KMEMLEAK_NOT_LEAK:
1705 kmemleak_not_leak(log->ptr);
1706 break;
1707 case KMEMLEAK_IGNORE:
1708 kmemleak_ignore(log->ptr);
1709 break;
1710 case KMEMLEAK_SCAN_AREA:
Catalin Marinasc017b4b2009-10-28 13:33:09 +00001711 kmemleak_scan_area(log->ptr, log->size, GFP_KERNEL);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001712 break;
1713 case KMEMLEAK_NO_SCAN:
1714 kmemleak_no_scan(log->ptr);
1715 break;
1716 default:
1717 WARN_ON(1);
1718 }
1719 }
1720}
1721
1722/*
1723 * Late initialization function.
1724 */
1725static int __init kmemleak_late_init(void)
1726{
1727 struct dentry *dentry;
1728
1729 atomic_set(&kmemleak_initialized, 1);
1730
1731 if (atomic_read(&kmemleak_error)) {
1732 /*
1733 * Some error occured and kmemleak was disabled. There is a
1734 * small chance that kmemleak_disable() was called immediately
1735 * after setting kmemleak_initialized and we may end up with
1736 * two clean-up threads but serialized by scan_mutex.
1737 */
Catalin Marinas179a8102009-09-07 10:14:42 +01001738 schedule_work(&cleanup_work);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001739 return -ENOMEM;
1740 }
1741
1742 dentry = debugfs_create_file("kmemleak", S_IRUGO, NULL, NULL,
1743 &kmemleak_fops);
1744 if (!dentry)
Joe Perchesae281062009-06-23 14:40:26 +01001745 pr_warning("Failed to create the debugfs kmemleak file\n");
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001746 mutex_lock(&scan_mutex);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001747 start_scan_thread();
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001748 mutex_unlock(&scan_mutex);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001749
1750 pr_info("Kernel memory leak detector initialized\n");
1751
1752 return 0;
1753}
1754late_initcall(kmemleak_late_init);