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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>
75#include <linux/gfp.h>
76#include <linux/fs.h>
77#include <linux/debugfs.h>
78#include <linux/seq_file.h>
79#include <linux/cpumask.h>
80#include <linux/spinlock.h>
81#include <linux/mutex.h>
82#include <linux/rcupdate.h>
83#include <linux/stacktrace.h>
84#include <linux/cache.h>
85#include <linux/percpu.h>
86#include <linux/hardirq.h>
87#include <linux/mmzone.h>
88#include <linux/slab.h>
89#include <linux/thread_info.h>
90#include <linux/err.h>
91#include <linux/uaccess.h>
92#include <linux/string.h>
93#include <linux/nodemask.h>
94#include <linux/mm.h>
Catalin Marinas179a8102009-09-07 10:14:42 +010095#include <linux/workqueue.h>
Catalin Marinas04609cc2009-10-28 13:33:12 +000096#include <linux/crc32.h>
Catalin Marinas3c7b4e62009-06-11 13:22:39 +010097
98#include <asm/sections.h>
99#include <asm/processor.h>
100#include <asm/atomic.h>
101
Pekka Enberg8e019362009-08-27 14:50:00 +0100102#include <linux/kmemcheck.h>
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100103#include <linux/kmemleak.h>
104
105/*
106 * Kmemleak configuration and common defines.
107 */
108#define MAX_TRACE 16 /* stack trace length */
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100109#define MSECS_MIN_AGE 5000 /* minimum object age for reporting */
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100110#define SECS_FIRST_SCAN 60 /* delay before the first scan */
111#define SECS_SCAN_WAIT 600 /* subsequent auto scanning delay */
Catalin Marinasaf986032009-08-27 14:29:12 +0100112#define MAX_SCAN_SIZE 4096 /* maximum size of a scanned block */
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100113
114#define BYTES_PER_POINTER sizeof(void *)
115
Catalin Marinas216c04b2009-06-17 18:29:02 +0100116/* GFP bitmask for kmemleak internal allocations */
117#define GFP_KMEMLEAK_MASK (GFP_KERNEL | GFP_ATOMIC)
118
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100119/* scanning area inside a memory block */
120struct kmemleak_scan_area {
121 struct hlist_node node;
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000122 unsigned long start;
123 size_t size;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100124};
125
Luis R. Rodrigueza1084c82009-09-04 17:44:52 -0700126#define KMEMLEAK_GREY 0
127#define KMEMLEAK_BLACK -1
128
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100129/*
130 * Structure holding the metadata for each allocated memory block.
131 * Modifications to such objects should be made while holding the
132 * object->lock. Insertions or deletions from object_list, gray_list or
133 * tree_node are already protected by the corresponding locks or mutex (see
134 * the notes on locking above). These objects are reference-counted
135 * (use_count) and freed using the RCU mechanism.
136 */
137struct kmemleak_object {
138 spinlock_t lock;
139 unsigned long flags; /* object status flags */
140 struct list_head object_list;
141 struct list_head gray_list;
142 struct prio_tree_node tree_node;
143 struct rcu_head rcu; /* object_list lockless traversal */
144 /* object usage count; object freed when use_count == 0 */
145 atomic_t use_count;
146 unsigned long pointer;
147 size_t size;
148 /* minimum number of a pointers found before it is considered leak */
149 int min_count;
150 /* the total number of pointers found pointing to this object */
151 int count;
Catalin Marinas04609cc2009-10-28 13:33:12 +0000152 /* checksum for detecting modified objects */
153 u32 checksum;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100154 /* memory ranges to be scanned inside an object (empty for all) */
155 struct hlist_head area_list;
156 unsigned long trace[MAX_TRACE];
157 unsigned int trace_len;
158 unsigned long jiffies; /* creation timestamp */
159 pid_t pid; /* pid of the current task */
160 char comm[TASK_COMM_LEN]; /* executable name */
161};
162
163/* flag representing the memory block allocation status */
164#define OBJECT_ALLOCATED (1 << 0)
165/* flag set after the first reporting of an unreference object */
166#define OBJECT_REPORTED (1 << 1)
167/* flag set to not scan the object */
168#define OBJECT_NO_SCAN (1 << 2)
169
Sergey Senozhatsky0494e082009-08-27 14:29:18 +0100170/* number of bytes to print per line; must be 16 or 32 */
171#define HEX_ROW_SIZE 16
172/* number of bytes to print at a time (1, 2, 4, 8) */
173#define HEX_GROUP_SIZE 1
174/* include ASCII after the hex output */
175#define HEX_ASCII 1
176/* max number of lines to be printed */
177#define HEX_MAX_LINES 2
178
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100179/* the list of all allocated objects */
180static LIST_HEAD(object_list);
181/* the list of gray-colored objects (see color_gray comment below) */
182static LIST_HEAD(gray_list);
183/* prio search tree for object boundaries */
184static struct prio_tree_root object_tree_root;
185/* rw_lock protecting the access to object_list and prio_tree_root */
186static DEFINE_RWLOCK(kmemleak_lock);
187
188/* allocation caches for kmemleak internal data */
189static struct kmem_cache *object_cache;
190static struct kmem_cache *scan_area_cache;
191
192/* set if tracing memory operations is enabled */
193static atomic_t kmemleak_enabled = ATOMIC_INIT(0);
194/* set in the late_initcall if there were no errors */
195static atomic_t kmemleak_initialized = ATOMIC_INIT(0);
196/* enables or disables early logging of the memory operations */
197static atomic_t kmemleak_early_log = ATOMIC_INIT(1);
198/* set if a fata kmemleak error has occurred */
199static atomic_t kmemleak_error = ATOMIC_INIT(0);
200
201/* minimum and maximum address that may be valid pointers */
202static unsigned long min_addr = ULONG_MAX;
203static unsigned long max_addr;
204
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100205static struct task_struct *scan_thread;
Catalin Marinasacf49682009-06-26 17:38:29 +0100206/* used to avoid reporting of recently allocated objects */
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100207static unsigned long jiffies_min_age;
Catalin Marinasacf49682009-06-26 17:38:29 +0100208static unsigned long jiffies_last_scan;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100209/* delay between automatic memory scannings */
210static signed long jiffies_scan_wait;
211/* enables or disables the task stacks scanning */
Catalin Marinase0a2a162009-06-26 17:38:25 +0100212static int kmemleak_stack_scan = 1;
Catalin Marinas4698c1f2009-06-26 17:38:27 +0100213/* protects the memory scanning, parameters and debug/kmemleak file access */
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100214static DEFINE_MUTEX(scan_mutex);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100215
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100216/*
Catalin Marinas20301172009-06-17 18:29:04 +0100217 * Early object allocation/freeing logging. Kmemleak is initialized after the
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100218 * kernel allocator. However, both the kernel allocator and kmemleak may
Catalin Marinas20301172009-06-17 18:29:04 +0100219 * allocate memory blocks which need to be tracked. Kmemleak defines an
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100220 * arbitrary buffer to hold the allocation/freeing information before it is
221 * fully initialized.
222 */
223
224/* kmemleak operation type for early logging */
225enum {
226 KMEMLEAK_ALLOC,
227 KMEMLEAK_FREE,
Catalin Marinas53238a62009-07-07 10:33:00 +0100228 KMEMLEAK_FREE_PART,
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100229 KMEMLEAK_NOT_LEAK,
230 KMEMLEAK_IGNORE,
231 KMEMLEAK_SCAN_AREA,
232 KMEMLEAK_NO_SCAN
233};
234
235/*
236 * Structure holding the information passed to kmemleak callbacks during the
237 * early logging.
238 */
239struct early_log {
240 int op_type; /* kmemleak operation type */
241 const void *ptr; /* allocated/freed memory block */
242 size_t size; /* memory block size */
243 int min_count; /* minimum reference count */
Catalin Marinasfd678962009-08-27 14:29:17 +0100244 unsigned long trace[MAX_TRACE]; /* stack trace */
245 unsigned int trace_len; /* stack trace length */
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100246};
247
248/* early logging buffer and current position */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100249static struct early_log
250 early_log[CONFIG_DEBUG_KMEMLEAK_EARLY_LOG_SIZE] __initdata;
251static int crt_early_log __initdata;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100252
253static void kmemleak_disable(void);
254
255/*
256 * Print a warning and dump the stack trace.
257 */
258#define kmemleak_warn(x...) do { \
259 pr_warning(x); \
260 dump_stack(); \
261} while (0)
262
263/*
264 * Macro invoked when a serious kmemleak condition occured and cannot be
Catalin Marinas20301172009-06-17 18:29:04 +0100265 * recovered from. Kmemleak will be disabled and further allocation/freeing
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100266 * tracing no longer available.
267 */
Catalin Marinas000814f2009-06-17 18:29:03 +0100268#define kmemleak_stop(x...) do { \
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100269 kmemleak_warn(x); \
270 kmemleak_disable(); \
271} while (0)
272
273/*
Sergey Senozhatsky0494e082009-08-27 14:29:18 +0100274 * Printing of the objects hex dump to the seq file. The number of lines to be
275 * printed is limited to HEX_MAX_LINES to prevent seq file spamming. The
276 * actual number of printed bytes depends on HEX_ROW_SIZE. It must be called
277 * with the object->lock held.
278 */
279static void hex_dump_object(struct seq_file *seq,
280 struct kmemleak_object *object)
281{
282 const u8 *ptr = (const u8 *)object->pointer;
283 int i, len, remaining;
284 unsigned char linebuf[HEX_ROW_SIZE * 5];
285
286 /* limit the number of lines to HEX_MAX_LINES */
287 remaining = len =
288 min(object->size, (size_t)(HEX_MAX_LINES * HEX_ROW_SIZE));
289
290 seq_printf(seq, " hex dump (first %d bytes):\n", len);
291 for (i = 0; i < len; i += HEX_ROW_SIZE) {
292 int linelen = min(remaining, HEX_ROW_SIZE);
293
294 remaining -= HEX_ROW_SIZE;
295 hex_dump_to_buffer(ptr + i, linelen, HEX_ROW_SIZE,
296 HEX_GROUP_SIZE, linebuf, sizeof(linebuf),
297 HEX_ASCII);
298 seq_printf(seq, " %s\n", linebuf);
299 }
300}
301
302/*
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100303 * Object colors, encoded with count and min_count:
304 * - white - orphan object, not enough references to it (count < min_count)
305 * - gray - not orphan, not marked as false positive (min_count == 0) or
306 * sufficient references to it (count >= min_count)
307 * - black - ignore, it doesn't contain references (e.g. text section)
308 * (min_count == -1). No function defined for this color.
309 * Newly created objects don't have any color assigned (object->count == -1)
310 * before the next memory scan when they become white.
311 */
Luis R. Rodriguez4a558dd2009-09-08 16:34:50 +0100312static bool color_white(const struct kmemleak_object *object)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100313{
Luis R. Rodrigueza1084c82009-09-04 17:44:52 -0700314 return object->count != KMEMLEAK_BLACK &&
315 object->count < object->min_count;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100316}
317
Luis R. Rodriguez4a558dd2009-09-08 16:34:50 +0100318static bool color_gray(const struct kmemleak_object *object)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100319{
Luis R. Rodrigueza1084c82009-09-04 17:44:52 -0700320 return object->min_count != KMEMLEAK_BLACK &&
321 object->count >= object->min_count;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100322}
323
324/*
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100325 * Objects are considered unreferenced only if their color is white, they have
326 * not be deleted and have a minimum age to avoid false positives caused by
327 * pointers temporarily stored in CPU registers.
328 */
Luis R. Rodriguez4a558dd2009-09-08 16:34:50 +0100329static bool unreferenced_object(struct kmemleak_object *object)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100330{
Catalin Marinas04609cc2009-10-28 13:33:12 +0000331 return (color_white(object) && object->flags & OBJECT_ALLOCATED) &&
Catalin Marinasacf49682009-06-26 17:38:29 +0100332 time_before_eq(object->jiffies + jiffies_min_age,
333 jiffies_last_scan);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100334}
335
336/*
Catalin Marinasbab4a342009-06-26 17:38:26 +0100337 * Printing of the unreferenced objects information to the seq file. The
338 * print_unreferenced function must be called with the object->lock held.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100339 */
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100340static void print_unreferenced(struct seq_file *seq,
341 struct kmemleak_object *object)
342{
343 int i;
Catalin Marinasfefdd332009-10-28 13:33:12 +0000344 unsigned int msecs_age = jiffies_to_msecs(jiffies - object->jiffies);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100345
Catalin Marinasbab4a342009-06-26 17:38:26 +0100346 seq_printf(seq, "unreferenced object 0x%08lx (size %zu):\n",
347 object->pointer, object->size);
Catalin Marinasfefdd332009-10-28 13:33:12 +0000348 seq_printf(seq, " comm \"%s\", pid %d, jiffies %lu (age %d.%03ds)\n",
349 object->comm, object->pid, object->jiffies,
350 msecs_age / 1000, msecs_age % 1000);
Sergey Senozhatsky0494e082009-08-27 14:29:18 +0100351 hex_dump_object(seq, object);
Catalin Marinasbab4a342009-06-26 17:38:26 +0100352 seq_printf(seq, " backtrace:\n");
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100353
354 for (i = 0; i < object->trace_len; i++) {
355 void *ptr = (void *)object->trace[i];
Catalin Marinasbab4a342009-06-26 17:38:26 +0100356 seq_printf(seq, " [<%p>] %pS\n", ptr, ptr);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100357 }
358}
359
360/*
361 * Print the kmemleak_object information. This function is used mainly for
362 * debugging special cases when kmemleak operations. It must be called with
363 * the object->lock held.
364 */
365static void dump_object_info(struct kmemleak_object *object)
366{
367 struct stack_trace trace;
368
369 trace.nr_entries = object->trace_len;
370 trace.entries = object->trace;
371
Joe Perchesae281062009-06-23 14:40:26 +0100372 pr_notice("Object 0x%08lx (size %zu):\n",
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100373 object->tree_node.start, object->size);
374 pr_notice(" comm \"%s\", pid %d, jiffies %lu\n",
375 object->comm, object->pid, object->jiffies);
376 pr_notice(" min_count = %d\n", object->min_count);
377 pr_notice(" count = %d\n", object->count);
Catalin Marinas189d84e2009-08-27 14:29:15 +0100378 pr_notice(" flags = 0x%lx\n", object->flags);
Catalin Marinas04609cc2009-10-28 13:33:12 +0000379 pr_notice(" checksum = %d\n", object->checksum);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100380 pr_notice(" backtrace:\n");
381 print_stack_trace(&trace, 4);
382}
383
384/*
385 * Look-up a memory block metadata (kmemleak_object) in the priority search
386 * tree based on a pointer value. If alias is 0, only values pointing to the
387 * beginning of the memory block are allowed. The kmemleak_lock must be held
388 * when calling this function.
389 */
390static struct kmemleak_object *lookup_object(unsigned long ptr, int alias)
391{
392 struct prio_tree_node *node;
393 struct prio_tree_iter iter;
394 struct kmemleak_object *object;
395
396 prio_tree_iter_init(&iter, &object_tree_root, ptr, ptr);
397 node = prio_tree_next(&iter);
398 if (node) {
399 object = prio_tree_entry(node, struct kmemleak_object,
400 tree_node);
401 if (!alias && object->pointer != ptr) {
Joe Perchesae281062009-06-23 14:40:26 +0100402 kmemleak_warn("Found object by alias");
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100403 object = NULL;
404 }
405 } else
406 object = NULL;
407
408 return object;
409}
410
411/*
412 * Increment the object use_count. Return 1 if successful or 0 otherwise. Note
413 * that once an object's use_count reached 0, the RCU freeing was already
414 * registered and the object should no longer be used. This function must be
415 * called under the protection of rcu_read_lock().
416 */
417static int get_object(struct kmemleak_object *object)
418{
419 return atomic_inc_not_zero(&object->use_count);
420}
421
422/*
423 * RCU callback to free a kmemleak_object.
424 */
425static void free_object_rcu(struct rcu_head *rcu)
426{
427 struct hlist_node *elem, *tmp;
428 struct kmemleak_scan_area *area;
429 struct kmemleak_object *object =
430 container_of(rcu, struct kmemleak_object, rcu);
431
432 /*
433 * Once use_count is 0 (guaranteed by put_object), there is no other
434 * code accessing this object, hence no need for locking.
435 */
436 hlist_for_each_entry_safe(area, elem, tmp, &object->area_list, node) {
437 hlist_del(elem);
438 kmem_cache_free(scan_area_cache, area);
439 }
440 kmem_cache_free(object_cache, object);
441}
442
443/*
444 * Decrement the object use_count. Once the count is 0, free the object using
445 * an RCU callback. Since put_object() may be called via the kmemleak_free() ->
446 * delete_object() path, the delayed RCU freeing ensures that there is no
447 * recursive call to the kernel allocator. Lock-less RCU object_list traversal
448 * is also possible.
449 */
450static void put_object(struct kmemleak_object *object)
451{
452 if (!atomic_dec_and_test(&object->use_count))
453 return;
454
455 /* should only get here after delete_object was called */
456 WARN_ON(object->flags & OBJECT_ALLOCATED);
457
458 call_rcu(&object->rcu, free_object_rcu);
459}
460
461/*
462 * Look up an object in the prio search tree and increase its use_count.
463 */
464static struct kmemleak_object *find_and_get_object(unsigned long ptr, int alias)
465{
466 unsigned long flags;
467 struct kmemleak_object *object = NULL;
468
469 rcu_read_lock();
470 read_lock_irqsave(&kmemleak_lock, flags);
471 if (ptr >= min_addr && ptr < max_addr)
472 object = lookup_object(ptr, alias);
473 read_unlock_irqrestore(&kmemleak_lock, flags);
474
475 /* check whether the object is still available */
476 if (object && !get_object(object))
477 object = NULL;
478 rcu_read_unlock();
479
480 return object;
481}
482
483/*
Catalin Marinasfd678962009-08-27 14:29:17 +0100484 * Save stack trace to the given array of MAX_TRACE size.
485 */
486static int __save_stack_trace(unsigned long *trace)
487{
488 struct stack_trace stack_trace;
489
490 stack_trace.max_entries = MAX_TRACE;
491 stack_trace.nr_entries = 0;
492 stack_trace.entries = trace;
493 stack_trace.skip = 2;
494 save_stack_trace(&stack_trace);
495
496 return stack_trace.nr_entries;
497}
498
499/*
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100500 * Create the metadata (struct kmemleak_object) corresponding to an allocated
501 * memory block and add it to the object_list and object_tree_root.
502 */
Catalin Marinasfd678962009-08-27 14:29:17 +0100503static struct kmemleak_object *create_object(unsigned long ptr, size_t size,
504 int min_count, gfp_t gfp)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100505{
506 unsigned long flags;
507 struct kmemleak_object *object;
508 struct prio_tree_node *node;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100509
Catalin Marinas216c04b2009-06-17 18:29:02 +0100510 object = kmem_cache_alloc(object_cache, gfp & GFP_KMEMLEAK_MASK);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100511 if (!object) {
Joe Perchesae281062009-06-23 14:40:26 +0100512 kmemleak_stop("Cannot allocate a kmemleak_object structure\n");
Catalin Marinasfd678962009-08-27 14:29:17 +0100513 return NULL;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100514 }
515
516 INIT_LIST_HEAD(&object->object_list);
517 INIT_LIST_HEAD(&object->gray_list);
518 INIT_HLIST_HEAD(&object->area_list);
519 spin_lock_init(&object->lock);
520 atomic_set(&object->use_count, 1);
Catalin Marinas04609cc2009-10-28 13:33:12 +0000521 object->flags = OBJECT_ALLOCATED;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100522 object->pointer = ptr;
523 object->size = size;
524 object->min_count = min_count;
Catalin Marinas04609cc2009-10-28 13:33:12 +0000525 object->count = 0; /* white color initially */
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100526 object->jiffies = jiffies;
Catalin Marinas04609cc2009-10-28 13:33:12 +0000527 object->checksum = 0;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100528
529 /* task information */
530 if (in_irq()) {
531 object->pid = 0;
532 strncpy(object->comm, "hardirq", sizeof(object->comm));
533 } else if (in_softirq()) {
534 object->pid = 0;
535 strncpy(object->comm, "softirq", sizeof(object->comm));
536 } else {
537 object->pid = current->pid;
538 /*
539 * There is a small chance of a race with set_task_comm(),
540 * however using get_task_comm() here may cause locking
541 * dependency issues with current->alloc_lock. In the worst
542 * case, the command line is not correct.
543 */
544 strncpy(object->comm, current->comm, sizeof(object->comm));
545 }
546
547 /* kernel backtrace */
Catalin Marinasfd678962009-08-27 14:29:17 +0100548 object->trace_len = __save_stack_trace(object->trace);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100549
550 INIT_PRIO_TREE_NODE(&object->tree_node);
551 object->tree_node.start = ptr;
552 object->tree_node.last = ptr + size - 1;
553
554 write_lock_irqsave(&kmemleak_lock, flags);
Luis R. Rodriguez0580a182009-09-08 17:32:34 +0100555
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100556 min_addr = min(min_addr, ptr);
557 max_addr = max(max_addr, ptr + size);
558 node = prio_tree_insert(&object_tree_root, &object->tree_node);
559 /*
560 * The code calling the kernel does not yet have the pointer to the
561 * memory block to be able to free it. However, we still hold the
562 * kmemleak_lock here in case parts of the kernel started freeing
563 * random memory blocks.
564 */
565 if (node != &object->tree_node) {
Joe Perchesae281062009-06-23 14:40:26 +0100566 kmemleak_stop("Cannot insert 0x%lx into the object search tree "
567 "(already existing)\n", ptr);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100568 object = lookup_object(ptr, 1);
Luis R. Rodriguez0580a182009-09-08 17:32:34 +0100569 spin_lock(&object->lock);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100570 dump_object_info(object);
Luis R. Rodriguez0580a182009-09-08 17:32:34 +0100571 spin_unlock(&object->lock);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100572
573 goto out;
574 }
575 list_add_tail_rcu(&object->object_list, &object_list);
576out:
577 write_unlock_irqrestore(&kmemleak_lock, flags);
Catalin Marinasfd678962009-08-27 14:29:17 +0100578 return object;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100579}
580
581/*
582 * Remove the metadata (struct kmemleak_object) for a memory block from the
583 * object_list and object_tree_root and decrement its use_count.
584 */
Catalin Marinas53238a62009-07-07 10:33:00 +0100585static void __delete_object(struct kmemleak_object *object)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100586{
587 unsigned long flags;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100588
589 write_lock_irqsave(&kmemleak_lock, flags);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100590 prio_tree_remove(&object_tree_root, &object->tree_node);
591 list_del_rcu(&object->object_list);
592 write_unlock_irqrestore(&kmemleak_lock, flags);
593
594 WARN_ON(!(object->flags & OBJECT_ALLOCATED));
Catalin Marinas53238a62009-07-07 10:33:00 +0100595 WARN_ON(atomic_read(&object->use_count) < 2);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100596
597 /*
598 * Locking here also ensures that the corresponding memory block
599 * cannot be freed when it is being scanned.
600 */
601 spin_lock_irqsave(&object->lock, flags);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100602 object->flags &= ~OBJECT_ALLOCATED;
603 spin_unlock_irqrestore(&object->lock, flags);
604 put_object(object);
605}
606
607/*
Catalin Marinas53238a62009-07-07 10:33:00 +0100608 * Look up the metadata (struct kmemleak_object) corresponding to ptr and
609 * delete it.
610 */
611static void delete_object_full(unsigned long ptr)
612{
613 struct kmemleak_object *object;
614
615 object = find_and_get_object(ptr, 0);
616 if (!object) {
617#ifdef DEBUG
618 kmemleak_warn("Freeing unknown object at 0x%08lx\n",
619 ptr);
620#endif
621 return;
622 }
623 __delete_object(object);
624 put_object(object);
625}
626
627/*
628 * Look up the metadata (struct kmemleak_object) corresponding to ptr and
629 * delete it. If the memory block is partially freed, the function may create
630 * additional metadata for the remaining parts of the block.
631 */
632static void delete_object_part(unsigned long ptr, size_t size)
633{
634 struct kmemleak_object *object;
635 unsigned long start, end;
636
637 object = find_and_get_object(ptr, 1);
638 if (!object) {
639#ifdef DEBUG
640 kmemleak_warn("Partially freeing unknown object at 0x%08lx "
641 "(size %zu)\n", ptr, size);
642#endif
643 return;
644 }
645 __delete_object(object);
646
647 /*
648 * Create one or two objects that may result from the memory block
649 * split. Note that partial freeing is only done by free_bootmem() and
650 * this happens before kmemleak_init() is called. The path below is
651 * only executed during early log recording in kmemleak_init(), so
652 * GFP_KERNEL is enough.
653 */
654 start = object->pointer;
655 end = object->pointer + object->size;
656 if (ptr > start)
657 create_object(start, ptr - start, object->min_count,
658 GFP_KERNEL);
659 if (ptr + size < end)
660 create_object(ptr + size, end - ptr - size, object->min_count,
661 GFP_KERNEL);
662
663 put_object(object);
664}
Luis R. Rodrigueza1084c82009-09-04 17:44:52 -0700665
666static void __paint_it(struct kmemleak_object *object, int color)
667{
668 object->min_count = color;
669 if (color == KMEMLEAK_BLACK)
670 object->flags |= OBJECT_NO_SCAN;
671}
672
673static void paint_it(struct kmemleak_object *object, int color)
674{
675 unsigned long flags;
676
677 spin_lock_irqsave(&object->lock, flags);
678 __paint_it(object, color);
679 spin_unlock_irqrestore(&object->lock, flags);
680}
681
682static void paint_ptr(unsigned long ptr, int color)
683{
684 struct kmemleak_object *object;
685
686 object = find_and_get_object(ptr, 0);
687 if (!object) {
688 kmemleak_warn("Trying to color unknown object "
689 "at 0x%08lx as %s\n", ptr,
690 (color == KMEMLEAK_GREY) ? "Grey" :
691 (color == KMEMLEAK_BLACK) ? "Black" : "Unknown");
692 return;
693 }
694 paint_it(object, color);
695 put_object(object);
696}
697
Catalin Marinas53238a62009-07-07 10:33:00 +0100698/*
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100699 * Make a object permanently as gray-colored so that it can no longer be
700 * reported as a leak. This is used in general to mark a false positive.
701 */
702static void make_gray_object(unsigned long ptr)
703{
Luis R. Rodrigueza1084c82009-09-04 17:44:52 -0700704 paint_ptr(ptr, KMEMLEAK_GREY);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100705}
706
707/*
708 * Mark the object as black-colored so that it is ignored from scans and
709 * reporting.
710 */
711static void make_black_object(unsigned long ptr)
712{
Luis R. Rodrigueza1084c82009-09-04 17:44:52 -0700713 paint_ptr(ptr, KMEMLEAK_BLACK);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100714}
715
716/*
717 * Add a scanning area to the object. If at least one such area is added,
718 * kmemleak will only scan these ranges rather than the whole memory block.
719 */
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000720static void add_scan_area(unsigned long ptr, size_t size, gfp_t gfp)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100721{
722 unsigned long flags;
723 struct kmemleak_object *object;
724 struct kmemleak_scan_area *area;
725
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000726 object = find_and_get_object(ptr, 1);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100727 if (!object) {
Joe Perchesae281062009-06-23 14:40:26 +0100728 kmemleak_warn("Adding scan area to unknown object at 0x%08lx\n",
729 ptr);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100730 return;
731 }
732
Catalin Marinas216c04b2009-06-17 18:29:02 +0100733 area = kmem_cache_alloc(scan_area_cache, gfp & GFP_KMEMLEAK_MASK);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100734 if (!area) {
Joe Perchesae281062009-06-23 14:40:26 +0100735 kmemleak_warn("Cannot allocate a scan area\n");
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100736 goto out;
737 }
738
739 spin_lock_irqsave(&object->lock, flags);
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000740 if (ptr + size > object->pointer + object->size) {
Joe Perchesae281062009-06-23 14:40:26 +0100741 kmemleak_warn("Scan area larger than object 0x%08lx\n", ptr);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100742 dump_object_info(object);
743 kmem_cache_free(scan_area_cache, area);
744 goto out_unlock;
745 }
746
747 INIT_HLIST_NODE(&area->node);
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000748 area->start = ptr;
749 area->size = size;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100750
751 hlist_add_head(&area->node, &object->area_list);
752out_unlock:
753 spin_unlock_irqrestore(&object->lock, flags);
754out:
755 put_object(object);
756}
757
758/*
759 * Set the OBJECT_NO_SCAN flag for the object corresponding to the give
760 * pointer. Such object will not be scanned by kmemleak but references to it
761 * are searched.
762 */
763static void object_no_scan(unsigned long ptr)
764{
765 unsigned long flags;
766 struct kmemleak_object *object;
767
768 object = find_and_get_object(ptr, 0);
769 if (!object) {
Joe Perchesae281062009-06-23 14:40:26 +0100770 kmemleak_warn("Not scanning unknown object at 0x%08lx\n", ptr);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100771 return;
772 }
773
774 spin_lock_irqsave(&object->lock, flags);
775 object->flags |= OBJECT_NO_SCAN;
776 spin_unlock_irqrestore(&object->lock, flags);
777 put_object(object);
778}
779
780/*
781 * Log an early kmemleak_* call to the early_log buffer. These calls will be
782 * processed later once kmemleak is fully initialized.
783 */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100784static void __init log_early(int op_type, const void *ptr, size_t size,
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000785 int min_count)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100786{
787 unsigned long flags;
788 struct early_log *log;
789
790 if (crt_early_log >= ARRAY_SIZE(early_log)) {
Catalin Marinasaddd72c2009-09-11 10:42:09 +0100791 pr_warning("Early log buffer exceeded, "
792 "please increase DEBUG_KMEMLEAK_EARLY_LOG_SIZE\n");
Catalin Marinasa9d90582009-06-25 10:16:11 +0100793 kmemleak_disable();
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100794 return;
795 }
796
797 /*
798 * There is no need for locking since the kernel is still in UP mode
799 * at this stage. Disabling the IRQs is enough.
800 */
801 local_irq_save(flags);
802 log = &early_log[crt_early_log];
803 log->op_type = op_type;
804 log->ptr = ptr;
805 log->size = size;
806 log->min_count = min_count;
Catalin Marinasfd678962009-08-27 14:29:17 +0100807 if (op_type == KMEMLEAK_ALLOC)
808 log->trace_len = __save_stack_trace(log->trace);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100809 crt_early_log++;
810 local_irq_restore(flags);
811}
812
813/*
Catalin Marinasfd678962009-08-27 14:29:17 +0100814 * Log an early allocated block and populate the stack trace.
815 */
816static void early_alloc(struct early_log *log)
817{
818 struct kmemleak_object *object;
819 unsigned long flags;
820 int i;
821
822 if (!atomic_read(&kmemleak_enabled) || !log->ptr || IS_ERR(log->ptr))
823 return;
824
825 /*
826 * RCU locking needed to ensure object is not freed via put_object().
827 */
828 rcu_read_lock();
829 object = create_object((unsigned long)log->ptr, log->size,
Tetsuo Handac1bcd6b2009-10-09 10:39:24 +0100830 log->min_count, GFP_ATOMIC);
Catalin Marinas0d5d1aa2009-10-09 10:30:34 +0100831 if (!object)
832 goto out;
Catalin Marinasfd678962009-08-27 14:29:17 +0100833 spin_lock_irqsave(&object->lock, flags);
834 for (i = 0; i < log->trace_len; i++)
835 object->trace[i] = log->trace[i];
836 object->trace_len = log->trace_len;
837 spin_unlock_irqrestore(&object->lock, flags);
Catalin Marinas0d5d1aa2009-10-09 10:30:34 +0100838out:
Catalin Marinasfd678962009-08-27 14:29:17 +0100839 rcu_read_unlock();
840}
841
842/*
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100843 * Memory allocation function callback. This function is called from the
844 * kernel allocators when a new block is allocated (kmem_cache_alloc, kmalloc,
845 * vmalloc etc.).
846 */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100847void __ref kmemleak_alloc(const void *ptr, size_t size, int min_count,
848 gfp_t gfp)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100849{
850 pr_debug("%s(0x%p, %zu, %d)\n", __func__, ptr, size, min_count);
851
852 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
853 create_object((unsigned long)ptr, size, min_count, gfp);
854 else if (atomic_read(&kmemleak_early_log))
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000855 log_early(KMEMLEAK_ALLOC, ptr, size, min_count);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100856}
857EXPORT_SYMBOL_GPL(kmemleak_alloc);
858
859/*
860 * Memory freeing function callback. This function is called from the kernel
861 * allocators when a block is freed (kmem_cache_free, kfree, vfree etc.).
862 */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100863void __ref kmemleak_free(const void *ptr)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100864{
865 pr_debug("%s(0x%p)\n", __func__, ptr);
866
867 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
Catalin Marinas53238a62009-07-07 10:33:00 +0100868 delete_object_full((unsigned long)ptr);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100869 else if (atomic_read(&kmemleak_early_log))
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000870 log_early(KMEMLEAK_FREE, ptr, 0, 0);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100871}
872EXPORT_SYMBOL_GPL(kmemleak_free);
873
874/*
Catalin Marinas53238a62009-07-07 10:33:00 +0100875 * Partial memory freeing function callback. This function is usually called
876 * from bootmem allocator when (part of) a memory block is freed.
877 */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100878void __ref kmemleak_free_part(const void *ptr, size_t size)
Catalin Marinas53238a62009-07-07 10:33:00 +0100879{
880 pr_debug("%s(0x%p)\n", __func__, ptr);
881
882 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
883 delete_object_part((unsigned long)ptr, size);
884 else if (atomic_read(&kmemleak_early_log))
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000885 log_early(KMEMLEAK_FREE_PART, ptr, size, 0);
Catalin Marinas53238a62009-07-07 10:33:00 +0100886}
887EXPORT_SYMBOL_GPL(kmemleak_free_part);
888
889/*
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100890 * Mark an already allocated memory block as a false positive. This will cause
891 * the block to no longer be reported as leak and always be scanned.
892 */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100893void __ref kmemleak_not_leak(const void *ptr)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100894{
895 pr_debug("%s(0x%p)\n", __func__, ptr);
896
897 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
898 make_gray_object((unsigned long)ptr);
899 else if (atomic_read(&kmemleak_early_log))
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000900 log_early(KMEMLEAK_NOT_LEAK, ptr, 0, 0);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100901}
902EXPORT_SYMBOL(kmemleak_not_leak);
903
904/*
905 * Ignore a memory block. This is usually done when it is known that the
906 * corresponding block is not a leak and does not contain any references to
907 * other allocated memory blocks.
908 */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100909void __ref kmemleak_ignore(const void *ptr)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100910{
911 pr_debug("%s(0x%p)\n", __func__, ptr);
912
913 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
914 make_black_object((unsigned long)ptr);
915 else if (atomic_read(&kmemleak_early_log))
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000916 log_early(KMEMLEAK_IGNORE, ptr, 0, 0);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100917}
918EXPORT_SYMBOL(kmemleak_ignore);
919
920/*
921 * Limit the range to be scanned in an allocated memory block.
922 */
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000923void __ref kmemleak_scan_area(const void *ptr, size_t size, gfp_t gfp)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100924{
925 pr_debug("%s(0x%p)\n", __func__, ptr);
926
927 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000928 add_scan_area((unsigned long)ptr, size, gfp);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100929 else if (atomic_read(&kmemleak_early_log))
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000930 log_early(KMEMLEAK_SCAN_AREA, ptr, size, 0);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100931}
932EXPORT_SYMBOL(kmemleak_scan_area);
933
934/*
935 * Inform kmemleak not to scan the given memory block.
936 */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100937void __ref kmemleak_no_scan(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 object_no_scan((unsigned long)ptr);
943 else if (atomic_read(&kmemleak_early_log))
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000944 log_early(KMEMLEAK_NO_SCAN, ptr, 0, 0);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100945}
946EXPORT_SYMBOL(kmemleak_no_scan);
947
948/*
Catalin Marinas04609cc2009-10-28 13:33:12 +0000949 * Update an object's checksum and return true if it was modified.
950 */
951static bool update_checksum(struct kmemleak_object *object)
952{
953 u32 old_csum = object->checksum;
954
955 if (!kmemcheck_is_obj_initialized(object->pointer, object->size))
956 return false;
957
958 object->checksum = crc32(0, (void *)object->pointer, object->size);
959 return object->checksum != old_csum;
960}
961
962/*
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100963 * Memory scanning is a long process and it needs to be interruptable. This
964 * function checks whether such interrupt condition occured.
965 */
966static int scan_should_stop(void)
967{
968 if (!atomic_read(&kmemleak_enabled))
969 return 1;
970
971 /*
972 * This function may be called from either process or kthread context,
973 * hence the need to check for both stop conditions.
974 */
975 if (current->mm)
976 return signal_pending(current);
977 else
978 return kthread_should_stop();
979
980 return 0;
981}
982
983/*
984 * Scan a memory block (exclusive range) for valid pointers and add those
985 * found to the gray list.
986 */
987static void scan_block(void *_start, void *_end,
Catalin Marinas4b8a9672009-07-07 10:32:56 +0100988 struct kmemleak_object *scanned, int allow_resched)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100989{
990 unsigned long *ptr;
991 unsigned long *start = PTR_ALIGN(_start, BYTES_PER_POINTER);
992 unsigned long *end = _end - (BYTES_PER_POINTER - 1);
993
994 for (ptr = start; ptr < end; ptr++) {
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100995 struct kmemleak_object *object;
Pekka Enberg8e019362009-08-27 14:50:00 +0100996 unsigned long flags;
997 unsigned long pointer;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100998
Catalin Marinas4b8a9672009-07-07 10:32:56 +0100999 if (allow_resched)
1000 cond_resched();
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001001 if (scan_should_stop())
1002 break;
1003
Pekka Enberg8e019362009-08-27 14:50:00 +01001004 /* don't scan uninitialized memory */
1005 if (!kmemcheck_is_obj_initialized((unsigned long)ptr,
1006 BYTES_PER_POINTER))
1007 continue;
1008
1009 pointer = *ptr;
1010
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001011 object = find_and_get_object(pointer, 1);
1012 if (!object)
1013 continue;
1014 if (object == scanned) {
1015 /* self referenced, ignore */
1016 put_object(object);
1017 continue;
1018 }
1019
1020 /*
1021 * Avoid the lockdep recursive warning on object->lock being
1022 * previously acquired in scan_object(). These locks are
1023 * enclosed by scan_mutex.
1024 */
1025 spin_lock_irqsave_nested(&object->lock, flags,
1026 SINGLE_DEPTH_NESTING);
1027 if (!color_white(object)) {
1028 /* non-orphan, ignored or new */
1029 spin_unlock_irqrestore(&object->lock, flags);
1030 put_object(object);
1031 continue;
1032 }
1033
1034 /*
1035 * Increase the object's reference count (number of pointers
1036 * to the memory block). If this count reaches the required
1037 * minimum, the object's color will become gray and it will be
1038 * added to the gray_list.
1039 */
1040 object->count++;
Catalin Marinas0587da42009-10-28 13:33:11 +00001041 if (color_gray(object)) {
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001042 list_add_tail(&object->gray_list, &gray_list);
Catalin Marinas0587da42009-10-28 13:33:11 +00001043 spin_unlock_irqrestore(&object->lock, flags);
1044 continue;
1045 }
1046
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001047 spin_unlock_irqrestore(&object->lock, flags);
Catalin Marinas0587da42009-10-28 13:33:11 +00001048 put_object(object);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001049 }
1050}
1051
1052/*
1053 * Scan a memory block corresponding to a kmemleak_object. A condition is
1054 * that object->use_count >= 1.
1055 */
1056static void scan_object(struct kmemleak_object *object)
1057{
1058 struct kmemleak_scan_area *area;
1059 struct hlist_node *elem;
1060 unsigned long flags;
1061
1062 /*
Uwe Kleine-König21ae2952009-10-07 15:21:09 +02001063 * Once the object->lock is acquired, the corresponding memory block
1064 * cannot be freed (the same lock is acquired in delete_object).
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001065 */
1066 spin_lock_irqsave(&object->lock, flags);
1067 if (object->flags & OBJECT_NO_SCAN)
1068 goto out;
1069 if (!(object->flags & OBJECT_ALLOCATED))
1070 /* already freed object */
1071 goto out;
Catalin Marinasaf986032009-08-27 14:29:12 +01001072 if (hlist_empty(&object->area_list)) {
1073 void *start = (void *)object->pointer;
1074 void *end = (void *)(object->pointer + object->size);
1075
1076 while (start < end && (object->flags & OBJECT_ALLOCATED) &&
1077 !(object->flags & OBJECT_NO_SCAN)) {
1078 scan_block(start, min(start + MAX_SCAN_SIZE, end),
1079 object, 0);
1080 start += MAX_SCAN_SIZE;
1081
1082 spin_unlock_irqrestore(&object->lock, flags);
1083 cond_resched();
1084 spin_lock_irqsave(&object->lock, flags);
1085 }
1086 } else
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001087 hlist_for_each_entry(area, elem, &object->area_list, node)
Catalin Marinasc017b4b2009-10-28 13:33:09 +00001088 scan_block((void *)area->start,
1089 (void *)(area->start + area->size),
1090 object, 0);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001091out:
1092 spin_unlock_irqrestore(&object->lock, flags);
1093}
1094
1095/*
Catalin Marinas04609cc2009-10-28 13:33:12 +00001096 * Scan the objects already referenced (gray objects). More objects will be
1097 * referenced and, if there are no memory leaks, all the objects are scanned.
1098 */
1099static void scan_gray_list(void)
1100{
1101 struct kmemleak_object *object, *tmp;
1102
1103 /*
1104 * The list traversal is safe for both tail additions and removals
1105 * from inside the loop. The kmemleak objects cannot be freed from
1106 * outside the loop because their use_count was incremented.
1107 */
1108 object = list_entry(gray_list.next, typeof(*object), gray_list);
1109 while (&object->gray_list != &gray_list) {
1110 cond_resched();
1111
1112 /* may add new objects to the list */
1113 if (!scan_should_stop())
1114 scan_object(object);
1115
1116 tmp = list_entry(object->gray_list.next, typeof(*object),
1117 gray_list);
1118
1119 /* remove the object from the list and release it */
1120 list_del(&object->gray_list);
1121 put_object(object);
1122
1123 object = tmp;
1124 }
1125 WARN_ON(!list_empty(&gray_list));
1126}
1127
1128/*
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001129 * Scan data sections and all the referenced memory blocks allocated via the
1130 * kernel's standard allocators. This function must be called with the
1131 * scan_mutex held.
1132 */
1133static void kmemleak_scan(void)
1134{
1135 unsigned long flags;
Catalin Marinas04609cc2009-10-28 13:33:12 +00001136 struct kmemleak_object *object;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001137 int i;
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001138 int new_leaks = 0;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001139
Catalin Marinasacf49682009-06-26 17:38:29 +01001140 jiffies_last_scan = jiffies;
1141
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001142 /* prepare the kmemleak_object's */
1143 rcu_read_lock();
1144 list_for_each_entry_rcu(object, &object_list, object_list) {
1145 spin_lock_irqsave(&object->lock, flags);
1146#ifdef DEBUG
1147 /*
1148 * With a few exceptions there should be a maximum of
1149 * 1 reference to any object at this point.
1150 */
1151 if (atomic_read(&object->use_count) > 1) {
Joe Perchesae281062009-06-23 14:40:26 +01001152 pr_debug("object->use_count = %d\n",
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001153 atomic_read(&object->use_count));
1154 dump_object_info(object);
1155 }
1156#endif
1157 /* reset the reference count (whiten the object) */
1158 object->count = 0;
1159 if (color_gray(object) && get_object(object))
1160 list_add_tail(&object->gray_list, &gray_list);
1161
1162 spin_unlock_irqrestore(&object->lock, flags);
1163 }
1164 rcu_read_unlock();
1165
1166 /* data/bss scanning */
Catalin Marinas4b8a9672009-07-07 10:32:56 +01001167 scan_block(_sdata, _edata, NULL, 1);
1168 scan_block(__bss_start, __bss_stop, NULL, 1);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001169
1170#ifdef CONFIG_SMP
1171 /* per-cpu sections scanning */
1172 for_each_possible_cpu(i)
1173 scan_block(__per_cpu_start + per_cpu_offset(i),
Catalin Marinas4b8a9672009-07-07 10:32:56 +01001174 __per_cpu_end + per_cpu_offset(i), NULL, 1);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001175#endif
1176
1177 /*
1178 * Struct page scanning for each node. The code below is not yet safe
1179 * with MEMORY_HOTPLUG.
1180 */
1181 for_each_online_node(i) {
1182 pg_data_t *pgdat = NODE_DATA(i);
1183 unsigned long start_pfn = pgdat->node_start_pfn;
1184 unsigned long end_pfn = start_pfn + pgdat->node_spanned_pages;
1185 unsigned long pfn;
1186
1187 for (pfn = start_pfn; pfn < end_pfn; pfn++) {
1188 struct page *page;
1189
1190 if (!pfn_valid(pfn))
1191 continue;
1192 page = pfn_to_page(pfn);
1193 /* only scan if page is in use */
1194 if (page_count(page) == 0)
1195 continue;
Catalin Marinas4b8a9672009-07-07 10:32:56 +01001196 scan_block(page, page + 1, NULL, 1);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001197 }
1198 }
1199
1200 /*
Catalin Marinas43ed5d62009-09-01 11:12:44 +01001201 * Scanning the task stacks (may introduce false negatives).
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001202 */
1203 if (kmemleak_stack_scan) {
Catalin Marinas43ed5d62009-09-01 11:12:44 +01001204 struct task_struct *p, *g;
1205
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001206 read_lock(&tasklist_lock);
Catalin Marinas43ed5d62009-09-01 11:12:44 +01001207 do_each_thread(g, p) {
1208 scan_block(task_stack_page(p), task_stack_page(p) +
1209 THREAD_SIZE, NULL, 0);
1210 } while_each_thread(g, p);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001211 read_unlock(&tasklist_lock);
1212 }
1213
1214 /*
1215 * Scan the objects already referenced from the sections scanned
Catalin Marinas04609cc2009-10-28 13:33:12 +00001216 * above.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001217 */
Catalin Marinas04609cc2009-10-28 13:33:12 +00001218 scan_gray_list();
Catalin Marinas25873622009-07-07 10:32:58 +01001219
1220 /*
Catalin Marinas04609cc2009-10-28 13:33:12 +00001221 * Check for new or unreferenced objects modified since the previous
1222 * scan and color them gray until the next scan.
Catalin Marinas25873622009-07-07 10:32:58 +01001223 */
1224 rcu_read_lock();
1225 list_for_each_entry_rcu(object, &object_list, object_list) {
1226 spin_lock_irqsave(&object->lock, flags);
Catalin Marinas04609cc2009-10-28 13:33:12 +00001227 if (color_white(object) && (object->flags & OBJECT_ALLOCATED)
1228 && update_checksum(object) && get_object(object)) {
1229 /* color it gray temporarily */
1230 object->count = object->min_count;
Catalin Marinas25873622009-07-07 10:32:58 +01001231 list_add_tail(&object->gray_list, &gray_list);
1232 }
1233 spin_unlock_irqrestore(&object->lock, flags);
1234 }
1235 rcu_read_unlock();
1236
Catalin Marinas04609cc2009-10-28 13:33:12 +00001237 /*
1238 * Re-scan the gray list for modified unreferenced objects.
1239 */
1240 scan_gray_list();
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001241
1242 /*
Catalin Marinas04609cc2009-10-28 13:33:12 +00001243 * If scanning was stopped do not report any new unreferenced objects.
Catalin Marinas17bb9e02009-06-29 17:13:56 +01001244 */
Catalin Marinas04609cc2009-10-28 13:33:12 +00001245 if (scan_should_stop())
Catalin Marinas17bb9e02009-06-29 17:13:56 +01001246 return;
1247
1248 /*
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001249 * Scanning result reporting.
1250 */
1251 rcu_read_lock();
1252 list_for_each_entry_rcu(object, &object_list, object_list) {
1253 spin_lock_irqsave(&object->lock, flags);
1254 if (unreferenced_object(object) &&
1255 !(object->flags & OBJECT_REPORTED)) {
1256 object->flags |= OBJECT_REPORTED;
1257 new_leaks++;
1258 }
1259 spin_unlock_irqrestore(&object->lock, flags);
1260 }
1261 rcu_read_unlock();
1262
1263 if (new_leaks)
1264 pr_info("%d new suspected memory leaks (see "
1265 "/sys/kernel/debug/kmemleak)\n", new_leaks);
1266
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001267}
1268
1269/*
1270 * Thread function performing automatic memory scanning. Unreferenced objects
1271 * at the end of a memory scan are reported but only the first time.
1272 */
1273static int kmemleak_scan_thread(void *arg)
1274{
1275 static int first_run = 1;
1276
Joe Perchesae281062009-06-23 14:40:26 +01001277 pr_info("Automatic memory scanning thread started\n");
Catalin Marinasbf2a76b2009-07-07 10:32:55 +01001278 set_user_nice(current, 10);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001279
1280 /*
1281 * Wait before the first scan to allow the system to fully initialize.
1282 */
1283 if (first_run) {
1284 first_run = 0;
1285 ssleep(SECS_FIRST_SCAN);
1286 }
1287
1288 while (!kthread_should_stop()) {
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001289 signed long timeout = jiffies_scan_wait;
1290
1291 mutex_lock(&scan_mutex);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001292 kmemleak_scan();
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001293 mutex_unlock(&scan_mutex);
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001294
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001295 /* wait before the next scan */
1296 while (timeout && !kthread_should_stop())
1297 timeout = schedule_timeout_interruptible(timeout);
1298 }
1299
Joe Perchesae281062009-06-23 14:40:26 +01001300 pr_info("Automatic memory scanning thread ended\n");
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001301
1302 return 0;
1303}
1304
1305/*
1306 * Start the automatic memory scanning thread. This function must be called
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001307 * with the scan_mutex held.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001308 */
Luis R. Rodriguez7eb0d5e2009-09-08 17:31:45 +01001309static void start_scan_thread(void)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001310{
1311 if (scan_thread)
1312 return;
1313 scan_thread = kthread_run(kmemleak_scan_thread, NULL, "kmemleak");
1314 if (IS_ERR(scan_thread)) {
Joe Perchesae281062009-06-23 14:40:26 +01001315 pr_warning("Failed to create the scan thread\n");
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001316 scan_thread = NULL;
1317 }
1318}
1319
1320/*
1321 * Stop the automatic memory scanning thread. This function must be called
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001322 * with the scan_mutex held.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001323 */
Luis R. Rodriguez7eb0d5e2009-09-08 17:31:45 +01001324static void stop_scan_thread(void)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001325{
1326 if (scan_thread) {
1327 kthread_stop(scan_thread);
1328 scan_thread = NULL;
1329 }
1330}
1331
1332/*
1333 * Iterate over the object_list and return the first valid object at or after
1334 * the required position with its use_count incremented. The function triggers
1335 * a memory scanning when the pos argument points to the first position.
1336 */
1337static void *kmemleak_seq_start(struct seq_file *seq, loff_t *pos)
1338{
1339 struct kmemleak_object *object;
1340 loff_t n = *pos;
Catalin Marinasb87324d2009-07-07 10:32:58 +01001341 int err;
1342
1343 err = mutex_lock_interruptible(&scan_mutex);
1344 if (err < 0)
1345 return ERR_PTR(err);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001346
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001347 rcu_read_lock();
1348 list_for_each_entry_rcu(object, &object_list, object_list) {
1349 if (n-- > 0)
1350 continue;
1351 if (get_object(object))
1352 goto out;
1353 }
1354 object = NULL;
1355out:
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001356 return object;
1357}
1358
1359/*
1360 * Return the next object in the object_list. The function decrements the
1361 * use_count of the previous object and increases that of the next one.
1362 */
1363static void *kmemleak_seq_next(struct seq_file *seq, void *v, loff_t *pos)
1364{
1365 struct kmemleak_object *prev_obj = v;
1366 struct kmemleak_object *next_obj = NULL;
1367 struct list_head *n = &prev_obj->object_list;
1368
1369 ++(*pos);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001370
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001371 list_for_each_continue_rcu(n, &object_list) {
1372 next_obj = list_entry(n, struct kmemleak_object, object_list);
1373 if (get_object(next_obj))
1374 break;
1375 }
Catalin Marinas288c8572009-07-07 10:32:57 +01001376
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001377 put_object(prev_obj);
1378 return next_obj;
1379}
1380
1381/*
1382 * Decrement the use_count of the last object required, if any.
1383 */
1384static void kmemleak_seq_stop(struct seq_file *seq, void *v)
1385{
Catalin Marinasb87324d2009-07-07 10:32:58 +01001386 if (!IS_ERR(v)) {
1387 /*
1388 * kmemleak_seq_start may return ERR_PTR if the scan_mutex
1389 * waiting was interrupted, so only release it if !IS_ERR.
1390 */
Catalin Marinasf5886c72009-07-29 16:26:57 +01001391 rcu_read_unlock();
Catalin Marinasb87324d2009-07-07 10:32:58 +01001392 mutex_unlock(&scan_mutex);
1393 if (v)
1394 put_object(v);
1395 }
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001396}
1397
1398/*
1399 * Print the information for an unreferenced object to the seq file.
1400 */
1401static int kmemleak_seq_show(struct seq_file *seq, void *v)
1402{
1403 struct kmemleak_object *object = v;
1404 unsigned long flags;
1405
1406 spin_lock_irqsave(&object->lock, flags);
Catalin Marinas288c8572009-07-07 10:32:57 +01001407 if ((object->flags & OBJECT_REPORTED) && unreferenced_object(object))
Catalin Marinas17bb9e02009-06-29 17:13:56 +01001408 print_unreferenced(seq, object);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001409 spin_unlock_irqrestore(&object->lock, flags);
1410 return 0;
1411}
1412
1413static const struct seq_operations kmemleak_seq_ops = {
1414 .start = kmemleak_seq_start,
1415 .next = kmemleak_seq_next,
1416 .stop = kmemleak_seq_stop,
1417 .show = kmemleak_seq_show,
1418};
1419
1420static int kmemleak_open(struct inode *inode, struct file *file)
1421{
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001422 if (!atomic_read(&kmemleak_enabled))
1423 return -EBUSY;
1424
Catalin Marinasb87324d2009-07-07 10:32:58 +01001425 return seq_open(file, &kmemleak_seq_ops);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001426}
1427
1428static int kmemleak_release(struct inode *inode, struct file *file)
1429{
Catalin Marinasb87324d2009-07-07 10:32:58 +01001430 return seq_release(inode, file);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001431}
1432
Catalin Marinas189d84e2009-08-27 14:29:15 +01001433static int dump_str_object_info(const char *str)
1434{
1435 unsigned long flags;
1436 struct kmemleak_object *object;
1437 unsigned long addr;
1438
1439 addr= simple_strtoul(str, NULL, 0);
1440 object = find_and_get_object(addr, 0);
1441 if (!object) {
1442 pr_info("Unknown object at 0x%08lx\n", addr);
1443 return -EINVAL;
1444 }
1445
1446 spin_lock_irqsave(&object->lock, flags);
1447 dump_object_info(object);
1448 spin_unlock_irqrestore(&object->lock, flags);
1449
1450 put_object(object);
1451 return 0;
1452}
1453
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001454/*
Luis R. Rodriguez30b37102009-09-04 17:44:51 -07001455 * We use grey instead of black to ensure we can do future scans on the same
1456 * objects. If we did not do future scans these black objects could
1457 * potentially contain references to newly allocated objects in the future and
1458 * we'd end up with false positives.
1459 */
1460static void kmemleak_clear(void)
1461{
1462 struct kmemleak_object *object;
1463 unsigned long flags;
1464
1465 rcu_read_lock();
1466 list_for_each_entry_rcu(object, &object_list, object_list) {
1467 spin_lock_irqsave(&object->lock, flags);
1468 if ((object->flags & OBJECT_REPORTED) &&
1469 unreferenced_object(object))
Luis R. Rodrigueza1084c82009-09-04 17:44:52 -07001470 __paint_it(object, KMEMLEAK_GREY);
Luis R. Rodriguez30b37102009-09-04 17:44:51 -07001471 spin_unlock_irqrestore(&object->lock, flags);
1472 }
1473 rcu_read_unlock();
1474}
1475
1476/*
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001477 * File write operation to configure kmemleak at run-time. The following
1478 * commands can be written to the /sys/kernel/debug/kmemleak file:
1479 * off - disable kmemleak (irreversible)
1480 * stack=on - enable the task stacks scanning
1481 * stack=off - disable the tasks stacks scanning
1482 * scan=on - start the automatic memory scanning thread
1483 * scan=off - stop the automatic memory scanning thread
1484 * scan=... - set the automatic memory scanning period in seconds (0 to
1485 * disable it)
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001486 * scan - trigger a memory scan
Luis R. Rodriguez30b37102009-09-04 17:44:51 -07001487 * clear - mark all current reported unreferenced kmemleak objects as
1488 * grey to ignore printing them
Catalin Marinas189d84e2009-08-27 14:29:15 +01001489 * dump=... - dump information about the object found at the given address
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001490 */
1491static ssize_t kmemleak_write(struct file *file, const char __user *user_buf,
1492 size_t size, loff_t *ppos)
1493{
1494 char buf[64];
1495 int buf_size;
Catalin Marinasb87324d2009-07-07 10:32:58 +01001496 int ret;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001497
1498 buf_size = min(size, (sizeof(buf) - 1));
1499 if (strncpy_from_user(buf, user_buf, buf_size) < 0)
1500 return -EFAULT;
1501 buf[buf_size] = 0;
1502
Catalin Marinasb87324d2009-07-07 10:32:58 +01001503 ret = mutex_lock_interruptible(&scan_mutex);
1504 if (ret < 0)
1505 return ret;
1506
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001507 if (strncmp(buf, "off", 3) == 0)
1508 kmemleak_disable();
1509 else if (strncmp(buf, "stack=on", 8) == 0)
1510 kmemleak_stack_scan = 1;
1511 else if (strncmp(buf, "stack=off", 9) == 0)
1512 kmemleak_stack_scan = 0;
1513 else if (strncmp(buf, "scan=on", 7) == 0)
1514 start_scan_thread();
1515 else if (strncmp(buf, "scan=off", 8) == 0)
1516 stop_scan_thread();
1517 else if (strncmp(buf, "scan=", 5) == 0) {
1518 unsigned long secs;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001519
Catalin Marinasb87324d2009-07-07 10:32:58 +01001520 ret = strict_strtoul(buf + 5, 0, &secs);
1521 if (ret < 0)
1522 goto out;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001523 stop_scan_thread();
1524 if (secs) {
1525 jiffies_scan_wait = msecs_to_jiffies(secs * 1000);
1526 start_scan_thread();
1527 }
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001528 } else if (strncmp(buf, "scan", 4) == 0)
1529 kmemleak_scan();
Luis R. Rodriguez30b37102009-09-04 17:44:51 -07001530 else if (strncmp(buf, "clear", 5) == 0)
1531 kmemleak_clear();
Catalin Marinas189d84e2009-08-27 14:29:15 +01001532 else if (strncmp(buf, "dump=", 5) == 0)
1533 ret = dump_str_object_info(buf + 5);
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001534 else
Catalin Marinasb87324d2009-07-07 10:32:58 +01001535 ret = -EINVAL;
1536
1537out:
1538 mutex_unlock(&scan_mutex);
1539 if (ret < 0)
1540 return ret;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001541
1542 /* ignore the rest of the buffer, only one command at a time */
1543 *ppos += size;
1544 return size;
1545}
1546
1547static const struct file_operations kmemleak_fops = {
1548 .owner = THIS_MODULE,
1549 .open = kmemleak_open,
1550 .read = seq_read,
1551 .write = kmemleak_write,
1552 .llseek = seq_lseek,
1553 .release = kmemleak_release,
1554};
1555
1556/*
1557 * Perform the freeing of the kmemleak internal objects after waiting for any
1558 * current memory scan to complete.
1559 */
Catalin Marinas179a8102009-09-07 10:14:42 +01001560static void kmemleak_do_cleanup(struct work_struct *work)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001561{
1562 struct kmemleak_object *object;
1563
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001564 mutex_lock(&scan_mutex);
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001565 stop_scan_thread();
1566
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001567 rcu_read_lock();
1568 list_for_each_entry_rcu(object, &object_list, object_list)
Catalin Marinas53238a62009-07-07 10:33:00 +01001569 delete_object_full(object->pointer);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001570 rcu_read_unlock();
1571 mutex_unlock(&scan_mutex);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001572}
1573
Catalin Marinas179a8102009-09-07 10:14:42 +01001574static DECLARE_WORK(cleanup_work, kmemleak_do_cleanup);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001575
1576/*
1577 * Disable kmemleak. No memory allocation/freeing will be traced once this
1578 * function is called. Disabling kmemleak is an irreversible operation.
1579 */
1580static void kmemleak_disable(void)
1581{
1582 /* atomically check whether it was already invoked */
1583 if (atomic_cmpxchg(&kmemleak_error, 0, 1))
1584 return;
1585
1586 /* stop any memory operation tracing */
1587 atomic_set(&kmemleak_early_log, 0);
1588 atomic_set(&kmemleak_enabled, 0);
1589
1590 /* check whether it is too early for a kernel thread */
1591 if (atomic_read(&kmemleak_initialized))
Catalin Marinas179a8102009-09-07 10:14:42 +01001592 schedule_work(&cleanup_work);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001593
1594 pr_info("Kernel memory leak detector disabled\n");
1595}
1596
1597/*
1598 * Allow boot-time kmemleak disabling (enabled by default).
1599 */
1600static int kmemleak_boot_config(char *str)
1601{
1602 if (!str)
1603 return -EINVAL;
1604 if (strcmp(str, "off") == 0)
1605 kmemleak_disable();
1606 else if (strcmp(str, "on") != 0)
1607 return -EINVAL;
1608 return 0;
1609}
1610early_param("kmemleak", kmemleak_boot_config);
1611
1612/*
Catalin Marinas20301172009-06-17 18:29:04 +01001613 * Kmemleak initialization.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001614 */
1615void __init kmemleak_init(void)
1616{
1617 int i;
1618 unsigned long flags;
1619
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001620 jiffies_min_age = msecs_to_jiffies(MSECS_MIN_AGE);
1621 jiffies_scan_wait = msecs_to_jiffies(SECS_SCAN_WAIT * 1000);
1622
1623 object_cache = KMEM_CACHE(kmemleak_object, SLAB_NOLEAKTRACE);
1624 scan_area_cache = KMEM_CACHE(kmemleak_scan_area, SLAB_NOLEAKTRACE);
1625 INIT_PRIO_TREE_ROOT(&object_tree_root);
1626
1627 /* the kernel is still in UP mode, so disabling the IRQs is enough */
1628 local_irq_save(flags);
1629 if (!atomic_read(&kmemleak_error)) {
1630 atomic_set(&kmemleak_enabled, 1);
1631 atomic_set(&kmemleak_early_log, 0);
1632 }
1633 local_irq_restore(flags);
1634
1635 /*
1636 * This is the point where tracking allocations is safe. Automatic
1637 * scanning is started during the late initcall. Add the early logged
1638 * callbacks to the kmemleak infrastructure.
1639 */
1640 for (i = 0; i < crt_early_log; i++) {
1641 struct early_log *log = &early_log[i];
1642
1643 switch (log->op_type) {
1644 case KMEMLEAK_ALLOC:
Catalin Marinasfd678962009-08-27 14:29:17 +01001645 early_alloc(log);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001646 break;
1647 case KMEMLEAK_FREE:
1648 kmemleak_free(log->ptr);
1649 break;
Catalin Marinas53238a62009-07-07 10:33:00 +01001650 case KMEMLEAK_FREE_PART:
1651 kmemleak_free_part(log->ptr, log->size);
1652 break;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001653 case KMEMLEAK_NOT_LEAK:
1654 kmemleak_not_leak(log->ptr);
1655 break;
1656 case KMEMLEAK_IGNORE:
1657 kmemleak_ignore(log->ptr);
1658 break;
1659 case KMEMLEAK_SCAN_AREA:
Catalin Marinasc017b4b2009-10-28 13:33:09 +00001660 kmemleak_scan_area(log->ptr, log->size, GFP_KERNEL);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001661 break;
1662 case KMEMLEAK_NO_SCAN:
1663 kmemleak_no_scan(log->ptr);
1664 break;
1665 default:
1666 WARN_ON(1);
1667 }
1668 }
1669}
1670
1671/*
1672 * Late initialization function.
1673 */
1674static int __init kmemleak_late_init(void)
1675{
1676 struct dentry *dentry;
1677
1678 atomic_set(&kmemleak_initialized, 1);
1679
1680 if (atomic_read(&kmemleak_error)) {
1681 /*
1682 * Some error occured and kmemleak was disabled. There is a
1683 * small chance that kmemleak_disable() was called immediately
1684 * after setting kmemleak_initialized and we may end up with
1685 * two clean-up threads but serialized by scan_mutex.
1686 */
Catalin Marinas179a8102009-09-07 10:14:42 +01001687 schedule_work(&cleanup_work);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001688 return -ENOMEM;
1689 }
1690
1691 dentry = debugfs_create_file("kmemleak", S_IRUGO, NULL, NULL,
1692 &kmemleak_fops);
1693 if (!dentry)
Joe Perchesae281062009-06-23 14:40:26 +01001694 pr_warning("Failed to create the debugfs kmemleak file\n");
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001695 mutex_lock(&scan_mutex);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001696 start_scan_thread();
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001697 mutex_unlock(&scan_mutex);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001698
1699 pr_info("Kernel memory leak detector initialized\n");
1700
1701 return 0;
1702}
1703late_initcall(kmemleak_late_init);