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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>
Paul Gortmakerb95f1b312011-10-16 02:01:52 -040072#include <linux/export.h>
Catalin Marinas3c7b4e62009-06-11 13:22:39 +010073#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>
Arun Sharma600634972011-07-26 16:09:06 -070099#include <linux/atomic.h>
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100100
Pekka Enberg8e019362009-08-27 14:50:00 +0100101#include <linux/kmemcheck.h>
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100102#include <linux/kmemleak.h>
103
104/*
105 * Kmemleak configuration and common defines.
106 */
107#define MAX_TRACE 16 /* stack trace length */
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100108#define MSECS_MIN_AGE 5000 /* minimum object age for reporting */
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100109#define SECS_FIRST_SCAN 60 /* delay before the first scan */
110#define SECS_SCAN_WAIT 600 /* subsequent auto scanning delay */
Catalin Marinasaf986032009-08-27 14:29:12 +0100111#define MAX_SCAN_SIZE 4096 /* maximum size of a scanned block */
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100112
113#define BYTES_PER_POINTER sizeof(void *)
114
Catalin Marinas216c04b2009-06-17 18:29:02 +0100115/* GFP bitmask for kmemleak internal allocations */
Catalin Marinas6ae4bd12011-01-27 10:30:26 +0000116#define gfp_kmemleak_mask(gfp) (((gfp) & (GFP_KERNEL | GFP_ATOMIC)) | \
117 __GFP_NORETRY | __GFP_NOMEMALLOC | \
118 __GFP_NOWARN)
Catalin Marinas216c04b2009-06-17 18:29:02 +0100119
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100120/* scanning area inside a memory block */
121struct kmemleak_scan_area {
122 struct hlist_node node;
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000123 unsigned long start;
124 size_t size;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100125};
126
Luis R. Rodrigueza1084c82009-09-04 17:44:52 -0700127#define KMEMLEAK_GREY 0
128#define KMEMLEAK_BLACK -1
129
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100130/*
131 * Structure holding the metadata for each allocated memory block.
132 * Modifications to such objects should be made while holding the
133 * object->lock. Insertions or deletions from object_list, gray_list or
134 * tree_node are already protected by the corresponding locks or mutex (see
135 * the notes on locking above). These objects are reference-counted
136 * (use_count) and freed using the RCU mechanism.
137 */
138struct kmemleak_object {
139 spinlock_t lock;
140 unsigned long flags; /* object status flags */
141 struct list_head object_list;
142 struct list_head gray_list;
143 struct prio_tree_node tree_node;
144 struct rcu_head rcu; /* object_list lockless traversal */
145 /* object usage count; object freed when use_count == 0 */
146 atomic_t use_count;
147 unsigned long pointer;
148 size_t size;
149 /* minimum number of a pointers found before it is considered leak */
150 int min_count;
151 /* the total number of pointers found pointing to this object */
152 int count;
Catalin Marinas04609ccc2009-10-28 13:33:12 +0000153 /* checksum for detecting modified objects */
154 u32 checksum;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100155 /* memory ranges to be scanned inside an object (empty for all) */
156 struct hlist_head area_list;
157 unsigned long trace[MAX_TRACE];
158 unsigned int trace_len;
159 unsigned long jiffies; /* creation timestamp */
160 pid_t pid; /* pid of the current task */
161 char comm[TASK_COMM_LEN]; /* executable name */
162};
163
164/* flag representing the memory block allocation status */
165#define OBJECT_ALLOCATED (1 << 0)
166/* flag set after the first reporting of an unreference object */
167#define OBJECT_REPORTED (1 << 1)
168/* flag set to not scan the object */
169#define OBJECT_NO_SCAN (1 << 2)
170
Sergey Senozhatsky0494e082009-08-27 14:29:18 +0100171/* number of bytes to print per line; must be 16 or 32 */
172#define HEX_ROW_SIZE 16
173/* number of bytes to print at a time (1, 2, 4, 8) */
174#define HEX_GROUP_SIZE 1
175/* include ASCII after the hex output */
176#define HEX_ASCII 1
177/* max number of lines to be printed */
178#define HEX_MAX_LINES 2
179
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100180/* the list of all allocated objects */
181static LIST_HEAD(object_list);
182/* the list of gray-colored objects (see color_gray comment below) */
183static LIST_HEAD(gray_list);
184/* prio search tree for object boundaries */
185static struct prio_tree_root object_tree_root;
186/* rw_lock protecting the access to object_list and prio_tree_root */
187static DEFINE_RWLOCK(kmemleak_lock);
188
189/* allocation caches for kmemleak internal data */
190static struct kmem_cache *object_cache;
191static struct kmem_cache *scan_area_cache;
192
193/* set if tracing memory operations is enabled */
194static atomic_t kmemleak_enabled = ATOMIC_INIT(0);
195/* set in the late_initcall if there were no errors */
196static atomic_t kmemleak_initialized = ATOMIC_INIT(0);
197/* enables or disables early logging of the memory operations */
198static atomic_t kmemleak_early_log = ATOMIC_INIT(1);
Catalin Marinas5f790202011-09-28 12:17:03 +0100199/* set if a kmemleak warning was issued */
200static atomic_t kmemleak_warning = ATOMIC_INIT(0);
201/* set if a fatal kmemleak error has occurred */
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100202static atomic_t kmemleak_error = ATOMIC_INIT(0);
203
204/* minimum and maximum address that may be valid pointers */
205static unsigned long min_addr = ULONG_MAX;
206static unsigned long max_addr;
207
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100208static struct task_struct *scan_thread;
Catalin Marinasacf49682009-06-26 17:38:29 +0100209/* used to avoid reporting of recently allocated objects */
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100210static unsigned long jiffies_min_age;
Catalin Marinasacf49682009-06-26 17:38:29 +0100211static unsigned long jiffies_last_scan;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100212/* delay between automatic memory scannings */
213static signed long jiffies_scan_wait;
214/* enables or disables the task stacks scanning */
Catalin Marinase0a2a162009-06-26 17:38:25 +0100215static int kmemleak_stack_scan = 1;
Catalin Marinas4698c1f2009-06-26 17:38:27 +0100216/* protects the memory scanning, parameters and debug/kmemleak file access */
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100217static DEFINE_MUTEX(scan_mutex);
Jason Baronab0155a2010-07-19 11:54:17 +0100218/* setting kmemleak=on, will set this var, skipping the disable */
219static int kmemleak_skip_disable;
220
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100221
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100222/*
Catalin Marinas20301172009-06-17 18:29:04 +0100223 * Early object allocation/freeing logging. Kmemleak is initialized after the
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100224 * kernel allocator. However, both the kernel allocator and kmemleak may
Catalin Marinas20301172009-06-17 18:29:04 +0100225 * allocate memory blocks which need to be tracked. Kmemleak defines an
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100226 * arbitrary buffer to hold the allocation/freeing information before it is
227 * fully initialized.
228 */
229
230/* kmemleak operation type for early logging */
231enum {
232 KMEMLEAK_ALLOC,
233 KMEMLEAK_FREE,
Catalin Marinas53238a62009-07-07 10:33:00 +0100234 KMEMLEAK_FREE_PART,
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100235 KMEMLEAK_NOT_LEAK,
236 KMEMLEAK_IGNORE,
237 KMEMLEAK_SCAN_AREA,
238 KMEMLEAK_NO_SCAN
239};
240
241/*
242 * Structure holding the information passed to kmemleak callbacks during the
243 * early logging.
244 */
245struct early_log {
246 int op_type; /* kmemleak operation type */
247 const void *ptr; /* allocated/freed memory block */
248 size_t size; /* memory block size */
249 int min_count; /* minimum reference count */
Catalin Marinasfd678962009-08-27 14:29:17 +0100250 unsigned long trace[MAX_TRACE]; /* stack trace */
251 unsigned int trace_len; /* stack trace length */
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100252};
253
254/* early logging buffer and current position */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100255static struct early_log
256 early_log[CONFIG_DEBUG_KMEMLEAK_EARLY_LOG_SIZE] __initdata;
257static int crt_early_log __initdata;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100258
259static void kmemleak_disable(void);
260
261/*
262 * Print a warning and dump the stack trace.
263 */
Catalin Marinas5f790202011-09-28 12:17:03 +0100264#define kmemleak_warn(x...) do { \
265 pr_warning(x); \
266 dump_stack(); \
267 atomic_set(&kmemleak_warning, 1); \
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100268} while (0)
269
270/*
Lucas De Marchi25985ed2011-03-30 22:57:33 -0300271 * Macro invoked when a serious kmemleak condition occurred and cannot be
Catalin Marinas20301172009-06-17 18:29:04 +0100272 * recovered from. Kmemleak will be disabled and further allocation/freeing
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100273 * tracing no longer available.
274 */
Catalin Marinas000814f2009-06-17 18:29:03 +0100275#define kmemleak_stop(x...) do { \
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100276 kmemleak_warn(x); \
277 kmemleak_disable(); \
278} while (0)
279
280/*
Sergey Senozhatsky0494e082009-08-27 14:29:18 +0100281 * Printing of the objects hex dump to the seq file. The number of lines to be
282 * printed is limited to HEX_MAX_LINES to prevent seq file spamming. The
283 * actual number of printed bytes depends on HEX_ROW_SIZE. It must be called
284 * with the object->lock held.
285 */
286static void hex_dump_object(struct seq_file *seq,
287 struct kmemleak_object *object)
288{
289 const u8 *ptr = (const u8 *)object->pointer;
290 int i, len, remaining;
291 unsigned char linebuf[HEX_ROW_SIZE * 5];
292
293 /* limit the number of lines to HEX_MAX_LINES */
294 remaining = len =
295 min(object->size, (size_t)(HEX_MAX_LINES * HEX_ROW_SIZE));
296
297 seq_printf(seq, " hex dump (first %d bytes):\n", len);
298 for (i = 0; i < len; i += HEX_ROW_SIZE) {
299 int linelen = min(remaining, HEX_ROW_SIZE);
300
301 remaining -= HEX_ROW_SIZE;
302 hex_dump_to_buffer(ptr + i, linelen, HEX_ROW_SIZE,
303 HEX_GROUP_SIZE, linebuf, sizeof(linebuf),
304 HEX_ASCII);
305 seq_printf(seq, " %s\n", linebuf);
306 }
307}
308
309/*
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100310 * Object colors, encoded with count and min_count:
311 * - white - orphan object, not enough references to it (count < min_count)
312 * - gray - not orphan, not marked as false positive (min_count == 0) or
313 * sufficient references to it (count >= min_count)
314 * - black - ignore, it doesn't contain references (e.g. text section)
315 * (min_count == -1). No function defined for this color.
316 * Newly created objects don't have any color assigned (object->count == -1)
317 * before the next memory scan when they become white.
318 */
Luis R. Rodriguez4a558dd2009-09-08 16:34:50 +0100319static bool color_white(const struct kmemleak_object *object)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100320{
Luis R. Rodrigueza1084c82009-09-04 17:44:52 -0700321 return object->count != KMEMLEAK_BLACK &&
322 object->count < object->min_count;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100323}
324
Luis R. Rodriguez4a558dd2009-09-08 16:34:50 +0100325static bool color_gray(const struct kmemleak_object *object)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100326{
Luis R. Rodrigueza1084c82009-09-04 17:44:52 -0700327 return object->min_count != KMEMLEAK_BLACK &&
328 object->count >= object->min_count;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100329}
330
331/*
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100332 * Objects are considered unreferenced only if their color is white, they have
333 * not be deleted and have a minimum age to avoid false positives caused by
334 * pointers temporarily stored in CPU registers.
335 */
Luis R. Rodriguez4a558dd2009-09-08 16:34:50 +0100336static bool unreferenced_object(struct kmemleak_object *object)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100337{
Catalin Marinas04609ccc2009-10-28 13:33:12 +0000338 return (color_white(object) && object->flags & OBJECT_ALLOCATED) &&
Catalin Marinasacf49682009-06-26 17:38:29 +0100339 time_before_eq(object->jiffies + jiffies_min_age,
340 jiffies_last_scan);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100341}
342
343/*
Catalin Marinasbab4a342009-06-26 17:38:26 +0100344 * Printing of the unreferenced objects information to the seq file. The
345 * print_unreferenced function must be called with the object->lock held.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100346 */
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100347static void print_unreferenced(struct seq_file *seq,
348 struct kmemleak_object *object)
349{
350 int i;
Catalin Marinasfefdd332009-10-28 13:33:12 +0000351 unsigned int msecs_age = jiffies_to_msecs(jiffies - object->jiffies);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100352
Catalin Marinasbab4a342009-06-26 17:38:26 +0100353 seq_printf(seq, "unreferenced object 0x%08lx (size %zu):\n",
354 object->pointer, object->size);
Catalin Marinasfefdd332009-10-28 13:33:12 +0000355 seq_printf(seq, " comm \"%s\", pid %d, jiffies %lu (age %d.%03ds)\n",
356 object->comm, object->pid, object->jiffies,
357 msecs_age / 1000, msecs_age % 1000);
Sergey Senozhatsky0494e082009-08-27 14:29:18 +0100358 hex_dump_object(seq, object);
Catalin Marinasbab4a342009-06-26 17:38:26 +0100359 seq_printf(seq, " backtrace:\n");
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100360
361 for (i = 0; i < object->trace_len; i++) {
362 void *ptr = (void *)object->trace[i];
Catalin Marinasbab4a342009-06-26 17:38:26 +0100363 seq_printf(seq, " [<%p>] %pS\n", ptr, ptr);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100364 }
365}
366
367/*
368 * Print the kmemleak_object information. This function is used mainly for
369 * debugging special cases when kmemleak operations. It must be called with
370 * the object->lock held.
371 */
372static void dump_object_info(struct kmemleak_object *object)
373{
374 struct stack_trace trace;
375
376 trace.nr_entries = object->trace_len;
377 trace.entries = object->trace;
378
Joe Perchesae281062009-06-23 14:40:26 +0100379 pr_notice("Object 0x%08lx (size %zu):\n",
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100380 object->tree_node.start, object->size);
381 pr_notice(" comm \"%s\", pid %d, jiffies %lu\n",
382 object->comm, object->pid, object->jiffies);
383 pr_notice(" min_count = %d\n", object->min_count);
384 pr_notice(" count = %d\n", object->count);
Catalin Marinas189d84e2009-08-27 14:29:15 +0100385 pr_notice(" flags = 0x%lx\n", object->flags);
Catalin Marinas04609ccc2009-10-28 13:33:12 +0000386 pr_notice(" checksum = %d\n", object->checksum);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100387 pr_notice(" backtrace:\n");
388 print_stack_trace(&trace, 4);
389}
390
391/*
392 * Look-up a memory block metadata (kmemleak_object) in the priority search
393 * tree based on a pointer value. If alias is 0, only values pointing to the
394 * beginning of the memory block are allowed. The kmemleak_lock must be held
395 * when calling this function.
396 */
397static struct kmemleak_object *lookup_object(unsigned long ptr, int alias)
398{
399 struct prio_tree_node *node;
400 struct prio_tree_iter iter;
401 struct kmemleak_object *object;
402
403 prio_tree_iter_init(&iter, &object_tree_root, ptr, ptr);
404 node = prio_tree_next(&iter);
405 if (node) {
406 object = prio_tree_entry(node, struct kmemleak_object,
407 tree_node);
408 if (!alias && object->pointer != ptr) {
Catalin Marinas5f790202011-09-28 12:17:03 +0100409 kmemleak_warn("Found object by alias at 0x%08lx\n",
410 ptr);
Catalin Marinasa7686a42010-07-19 11:54:16 +0100411 dump_object_info(object);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100412 object = NULL;
413 }
414 } else
415 object = NULL;
416
417 return object;
418}
419
420/*
421 * Increment the object use_count. Return 1 if successful or 0 otherwise. Note
422 * that once an object's use_count reached 0, the RCU freeing was already
423 * registered and the object should no longer be used. This function must be
424 * called under the protection of rcu_read_lock().
425 */
426static int get_object(struct kmemleak_object *object)
427{
428 return atomic_inc_not_zero(&object->use_count);
429}
430
431/*
432 * RCU callback to free a kmemleak_object.
433 */
434static void free_object_rcu(struct rcu_head *rcu)
435{
436 struct hlist_node *elem, *tmp;
437 struct kmemleak_scan_area *area;
438 struct kmemleak_object *object =
439 container_of(rcu, struct kmemleak_object, rcu);
440
441 /*
442 * Once use_count is 0 (guaranteed by put_object), there is no other
443 * code accessing this object, hence no need for locking.
444 */
445 hlist_for_each_entry_safe(area, elem, tmp, &object->area_list, node) {
446 hlist_del(elem);
447 kmem_cache_free(scan_area_cache, area);
448 }
449 kmem_cache_free(object_cache, object);
450}
451
452/*
453 * Decrement the object use_count. Once the count is 0, free the object using
454 * an RCU callback. Since put_object() may be called via the kmemleak_free() ->
455 * delete_object() path, the delayed RCU freeing ensures that there is no
456 * recursive call to the kernel allocator. Lock-less RCU object_list traversal
457 * is also possible.
458 */
459static void put_object(struct kmemleak_object *object)
460{
461 if (!atomic_dec_and_test(&object->use_count))
462 return;
463
464 /* should only get here after delete_object was called */
465 WARN_ON(object->flags & OBJECT_ALLOCATED);
466
467 call_rcu(&object->rcu, free_object_rcu);
468}
469
470/*
471 * Look up an object in the prio search tree and increase its use_count.
472 */
473static struct kmemleak_object *find_and_get_object(unsigned long ptr, int alias)
474{
475 unsigned long flags;
476 struct kmemleak_object *object = NULL;
477
478 rcu_read_lock();
479 read_lock_irqsave(&kmemleak_lock, flags);
480 if (ptr >= min_addr && ptr < max_addr)
481 object = lookup_object(ptr, alias);
482 read_unlock_irqrestore(&kmemleak_lock, flags);
483
484 /* check whether the object is still available */
485 if (object && !get_object(object))
486 object = NULL;
487 rcu_read_unlock();
488
489 return object;
490}
491
492/*
Catalin Marinasfd678962009-08-27 14:29:17 +0100493 * Save stack trace to the given array of MAX_TRACE size.
494 */
495static int __save_stack_trace(unsigned long *trace)
496{
497 struct stack_trace stack_trace;
498
499 stack_trace.max_entries = MAX_TRACE;
500 stack_trace.nr_entries = 0;
501 stack_trace.entries = trace;
502 stack_trace.skip = 2;
503 save_stack_trace(&stack_trace);
504
505 return stack_trace.nr_entries;
506}
507
508/*
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100509 * Create the metadata (struct kmemleak_object) corresponding to an allocated
510 * memory block and add it to the object_list and object_tree_root.
511 */
Catalin Marinasfd678962009-08-27 14:29:17 +0100512static struct kmemleak_object *create_object(unsigned long ptr, size_t size,
513 int min_count, gfp_t gfp)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100514{
515 unsigned long flags;
516 struct kmemleak_object *object;
517 struct prio_tree_node *node;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100518
Catalin Marinas6ae4bd12011-01-27 10:30:26 +0000519 object = kmem_cache_alloc(object_cache, gfp_kmemleak_mask(gfp));
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100520 if (!object) {
Catalin Marinas6ae4bd12011-01-27 10:30:26 +0000521 pr_warning("Cannot allocate a kmemleak_object structure\n");
522 kmemleak_disable();
Catalin Marinasfd678962009-08-27 14:29:17 +0100523 return NULL;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100524 }
525
526 INIT_LIST_HEAD(&object->object_list);
527 INIT_LIST_HEAD(&object->gray_list);
528 INIT_HLIST_HEAD(&object->area_list);
529 spin_lock_init(&object->lock);
530 atomic_set(&object->use_count, 1);
Catalin Marinas04609ccc2009-10-28 13:33:12 +0000531 object->flags = OBJECT_ALLOCATED;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100532 object->pointer = ptr;
533 object->size = size;
534 object->min_count = min_count;
Catalin Marinas04609ccc2009-10-28 13:33:12 +0000535 object->count = 0; /* white color initially */
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100536 object->jiffies = jiffies;
Catalin Marinas04609ccc2009-10-28 13:33:12 +0000537 object->checksum = 0;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100538
539 /* task information */
540 if (in_irq()) {
541 object->pid = 0;
542 strncpy(object->comm, "hardirq", sizeof(object->comm));
543 } else if (in_softirq()) {
544 object->pid = 0;
545 strncpy(object->comm, "softirq", sizeof(object->comm));
546 } else {
547 object->pid = current->pid;
548 /*
549 * There is a small chance of a race with set_task_comm(),
550 * however using get_task_comm() here may cause locking
551 * dependency issues with current->alloc_lock. In the worst
552 * case, the command line is not correct.
553 */
554 strncpy(object->comm, current->comm, sizeof(object->comm));
555 }
556
557 /* kernel backtrace */
Catalin Marinasfd678962009-08-27 14:29:17 +0100558 object->trace_len = __save_stack_trace(object->trace);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100559
560 INIT_PRIO_TREE_NODE(&object->tree_node);
561 object->tree_node.start = ptr;
562 object->tree_node.last = ptr + size - 1;
563
564 write_lock_irqsave(&kmemleak_lock, flags);
Luis R. Rodriguez0580a182009-09-08 17:32:34 +0100565
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100566 min_addr = min(min_addr, ptr);
567 max_addr = max(max_addr, ptr + size);
568 node = prio_tree_insert(&object_tree_root, &object->tree_node);
569 /*
570 * The code calling the kernel does not yet have the pointer to the
571 * memory block to be able to free it. However, we still hold the
572 * kmemleak_lock here in case parts of the kernel started freeing
573 * random memory blocks.
574 */
575 if (node != &object->tree_node) {
Joe Perchesae281062009-06-23 14:40:26 +0100576 kmemleak_stop("Cannot insert 0x%lx into the object search tree "
577 "(already existing)\n", ptr);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100578 object = lookup_object(ptr, 1);
Luis R. Rodriguez0580a182009-09-08 17:32:34 +0100579 spin_lock(&object->lock);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100580 dump_object_info(object);
Luis R. Rodriguez0580a182009-09-08 17:32:34 +0100581 spin_unlock(&object->lock);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100582
583 goto out;
584 }
585 list_add_tail_rcu(&object->object_list, &object_list);
586out:
587 write_unlock_irqrestore(&kmemleak_lock, flags);
Catalin Marinasfd678962009-08-27 14:29:17 +0100588 return object;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100589}
590
591/*
592 * Remove the metadata (struct kmemleak_object) for a memory block from the
593 * object_list and object_tree_root and decrement its use_count.
594 */
Catalin Marinas53238a62009-07-07 10:33:00 +0100595static void __delete_object(struct kmemleak_object *object)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100596{
597 unsigned long flags;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100598
599 write_lock_irqsave(&kmemleak_lock, flags);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100600 prio_tree_remove(&object_tree_root, &object->tree_node);
601 list_del_rcu(&object->object_list);
602 write_unlock_irqrestore(&kmemleak_lock, flags);
603
604 WARN_ON(!(object->flags & OBJECT_ALLOCATED));
Catalin Marinas53238a62009-07-07 10:33:00 +0100605 WARN_ON(atomic_read(&object->use_count) < 2);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100606
607 /*
608 * Locking here also ensures that the corresponding memory block
609 * cannot be freed when it is being scanned.
610 */
611 spin_lock_irqsave(&object->lock, flags);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100612 object->flags &= ~OBJECT_ALLOCATED;
613 spin_unlock_irqrestore(&object->lock, flags);
614 put_object(object);
615}
616
617/*
Catalin Marinas53238a62009-07-07 10:33:00 +0100618 * Look up the metadata (struct kmemleak_object) corresponding to ptr and
619 * delete it.
620 */
621static void delete_object_full(unsigned long ptr)
622{
623 struct kmemleak_object *object;
624
625 object = find_and_get_object(ptr, 0);
626 if (!object) {
627#ifdef DEBUG
628 kmemleak_warn("Freeing unknown object at 0x%08lx\n",
629 ptr);
630#endif
631 return;
632 }
633 __delete_object(object);
634 put_object(object);
635}
636
637/*
638 * Look up the metadata (struct kmemleak_object) corresponding to ptr and
639 * delete it. If the memory block is partially freed, the function may create
640 * additional metadata for the remaining parts of the block.
641 */
642static void delete_object_part(unsigned long ptr, size_t size)
643{
644 struct kmemleak_object *object;
645 unsigned long start, end;
646
647 object = find_and_get_object(ptr, 1);
648 if (!object) {
649#ifdef DEBUG
650 kmemleak_warn("Partially freeing unknown object at 0x%08lx "
651 "(size %zu)\n", ptr, size);
652#endif
653 return;
654 }
655 __delete_object(object);
656
657 /*
658 * Create one or two objects that may result from the memory block
659 * split. Note that partial freeing is only done by free_bootmem() and
660 * this happens before kmemleak_init() is called. The path below is
661 * only executed during early log recording in kmemleak_init(), so
662 * GFP_KERNEL is enough.
663 */
664 start = object->pointer;
665 end = object->pointer + object->size;
666 if (ptr > start)
667 create_object(start, ptr - start, object->min_count,
668 GFP_KERNEL);
669 if (ptr + size < end)
670 create_object(ptr + size, end - ptr - size, object->min_count,
671 GFP_KERNEL);
672
673 put_object(object);
674}
Luis R. Rodrigueza1084c82009-09-04 17:44:52 -0700675
676static void __paint_it(struct kmemleak_object *object, int color)
677{
678 object->min_count = color;
679 if (color == KMEMLEAK_BLACK)
680 object->flags |= OBJECT_NO_SCAN;
681}
682
683static void paint_it(struct kmemleak_object *object, int color)
684{
685 unsigned long flags;
686
687 spin_lock_irqsave(&object->lock, flags);
688 __paint_it(object, color);
689 spin_unlock_irqrestore(&object->lock, flags);
690}
691
692static void paint_ptr(unsigned long ptr, int color)
693{
694 struct kmemleak_object *object;
695
696 object = find_and_get_object(ptr, 0);
697 if (!object) {
698 kmemleak_warn("Trying to color unknown object "
699 "at 0x%08lx as %s\n", ptr,
700 (color == KMEMLEAK_GREY) ? "Grey" :
701 (color == KMEMLEAK_BLACK) ? "Black" : "Unknown");
702 return;
703 }
704 paint_it(object, color);
705 put_object(object);
706}
707
Catalin Marinas53238a62009-07-07 10:33:00 +0100708/*
Holger Hans Peter Freyther145b64b2010-07-22 19:54:13 +0800709 * Mark an object permanently as gray-colored so that it can no longer be
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100710 * reported as a leak. This is used in general to mark a false positive.
711 */
712static void make_gray_object(unsigned long ptr)
713{
Luis R. Rodrigueza1084c82009-09-04 17:44:52 -0700714 paint_ptr(ptr, KMEMLEAK_GREY);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100715}
716
717/*
718 * Mark the object as black-colored so that it is ignored from scans and
719 * reporting.
720 */
721static void make_black_object(unsigned long ptr)
722{
Luis R. Rodrigueza1084c82009-09-04 17:44:52 -0700723 paint_ptr(ptr, KMEMLEAK_BLACK);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100724}
725
726/*
727 * Add a scanning area to the object. If at least one such area is added,
728 * kmemleak will only scan these ranges rather than the whole memory block.
729 */
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000730static void add_scan_area(unsigned long ptr, size_t size, gfp_t gfp)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100731{
732 unsigned long flags;
733 struct kmemleak_object *object;
734 struct kmemleak_scan_area *area;
735
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000736 object = find_and_get_object(ptr, 1);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100737 if (!object) {
Joe Perchesae281062009-06-23 14:40:26 +0100738 kmemleak_warn("Adding scan area to unknown object at 0x%08lx\n",
739 ptr);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100740 return;
741 }
742
Catalin Marinas6ae4bd12011-01-27 10:30:26 +0000743 area = kmem_cache_alloc(scan_area_cache, gfp_kmemleak_mask(gfp));
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100744 if (!area) {
Catalin Marinas6ae4bd12011-01-27 10:30:26 +0000745 pr_warning("Cannot allocate a scan area\n");
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100746 goto out;
747 }
748
749 spin_lock_irqsave(&object->lock, flags);
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000750 if (ptr + size > object->pointer + object->size) {
Joe Perchesae281062009-06-23 14:40:26 +0100751 kmemleak_warn("Scan area larger than object 0x%08lx\n", ptr);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100752 dump_object_info(object);
753 kmem_cache_free(scan_area_cache, area);
754 goto out_unlock;
755 }
756
757 INIT_HLIST_NODE(&area->node);
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000758 area->start = ptr;
759 area->size = size;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100760
761 hlist_add_head(&area->node, &object->area_list);
762out_unlock:
763 spin_unlock_irqrestore(&object->lock, flags);
764out:
765 put_object(object);
766}
767
768/*
769 * Set the OBJECT_NO_SCAN flag for the object corresponding to the give
770 * pointer. Such object will not be scanned by kmemleak but references to it
771 * are searched.
772 */
773static void object_no_scan(unsigned long ptr)
774{
775 unsigned long flags;
776 struct kmemleak_object *object;
777
778 object = find_and_get_object(ptr, 0);
779 if (!object) {
Joe Perchesae281062009-06-23 14:40:26 +0100780 kmemleak_warn("Not scanning unknown object at 0x%08lx\n", ptr);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100781 return;
782 }
783
784 spin_lock_irqsave(&object->lock, flags);
785 object->flags |= OBJECT_NO_SCAN;
786 spin_unlock_irqrestore(&object->lock, flags);
787 put_object(object);
788}
789
790/*
791 * Log an early kmemleak_* call to the early_log buffer. These calls will be
792 * processed later once kmemleak is fully initialized.
793 */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100794static void __init log_early(int op_type, const void *ptr, size_t size,
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000795 int min_count)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100796{
797 unsigned long flags;
798 struct early_log *log;
799
Catalin Marinasb6693002011-09-28 17:22:56 +0100800 if (atomic_read(&kmemleak_error)) {
801 /* kmemleak stopped recording, just count the requests */
802 crt_early_log++;
803 return;
804 }
805
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100806 if (crt_early_log >= ARRAY_SIZE(early_log)) {
Catalin Marinasa9d90582009-06-25 10:16:11 +0100807 kmemleak_disable();
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100808 return;
809 }
810
811 /*
812 * There is no need for locking since the kernel is still in UP mode
813 * at this stage. Disabling the IRQs is enough.
814 */
815 local_irq_save(flags);
816 log = &early_log[crt_early_log];
817 log->op_type = op_type;
818 log->ptr = ptr;
819 log->size = size;
820 log->min_count = min_count;
Catalin Marinas5f790202011-09-28 12:17:03 +0100821 log->trace_len = __save_stack_trace(log->trace);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100822 crt_early_log++;
823 local_irq_restore(flags);
824}
825
826/*
Catalin Marinasfd678962009-08-27 14:29:17 +0100827 * Log an early allocated block and populate the stack trace.
828 */
829static void early_alloc(struct early_log *log)
830{
831 struct kmemleak_object *object;
832 unsigned long flags;
833 int i;
834
835 if (!atomic_read(&kmemleak_enabled) || !log->ptr || IS_ERR(log->ptr))
836 return;
837
838 /*
839 * RCU locking needed to ensure object is not freed via put_object().
840 */
841 rcu_read_lock();
842 object = create_object((unsigned long)log->ptr, log->size,
Tetsuo Handac1bcd6b2009-10-09 10:39:24 +0100843 log->min_count, GFP_ATOMIC);
Catalin Marinas0d5d1aa2009-10-09 10:30:34 +0100844 if (!object)
845 goto out;
Catalin Marinasfd678962009-08-27 14:29:17 +0100846 spin_lock_irqsave(&object->lock, flags);
847 for (i = 0; i < log->trace_len; i++)
848 object->trace[i] = log->trace[i];
849 object->trace_len = log->trace_len;
850 spin_unlock_irqrestore(&object->lock, flags);
Catalin Marinas0d5d1aa2009-10-09 10:30:34 +0100851out:
Catalin Marinasfd678962009-08-27 14:29:17 +0100852 rcu_read_unlock();
853}
854
Catalin Marinasa2b6bf62010-07-19 11:54:17 +0100855/**
856 * kmemleak_alloc - register a newly allocated object
857 * @ptr: pointer to beginning of the object
858 * @size: size of the object
859 * @min_count: minimum number of references to this object. If during memory
860 * scanning a number of references less than @min_count is found,
861 * the object is reported as a memory leak. If @min_count is 0,
862 * the object is never reported as a leak. If @min_count is -1,
863 * the object is ignored (not scanned and not reported as a leak)
864 * @gfp: kmalloc() flags used for kmemleak internal memory allocations
865 *
866 * This function is called from the kernel allocators when a new object
867 * (memory block) is allocated (kmem_cache_alloc, kmalloc, vmalloc etc.).
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100868 */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100869void __ref kmemleak_alloc(const void *ptr, size_t size, int min_count,
870 gfp_t gfp)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100871{
872 pr_debug("%s(0x%p, %zu, %d)\n", __func__, ptr, size, min_count);
873
874 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
875 create_object((unsigned long)ptr, size, min_count, gfp);
876 else if (atomic_read(&kmemleak_early_log))
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000877 log_early(KMEMLEAK_ALLOC, ptr, size, min_count);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100878}
879EXPORT_SYMBOL_GPL(kmemleak_alloc);
880
Catalin Marinasa2b6bf62010-07-19 11:54:17 +0100881/**
882 * kmemleak_free - unregister a previously registered object
883 * @ptr: pointer to beginning of the object
884 *
885 * This function is called from the kernel allocators when an object (memory
886 * block) is freed (kmem_cache_free, kfree, vfree etc.).
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100887 */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100888void __ref kmemleak_free(const void *ptr)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100889{
890 pr_debug("%s(0x%p)\n", __func__, ptr);
891
892 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
Catalin Marinas53238a62009-07-07 10:33:00 +0100893 delete_object_full((unsigned long)ptr);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100894 else if (atomic_read(&kmemleak_early_log))
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000895 log_early(KMEMLEAK_FREE, ptr, 0, 0);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100896}
897EXPORT_SYMBOL_GPL(kmemleak_free);
898
Catalin Marinasa2b6bf62010-07-19 11:54:17 +0100899/**
900 * kmemleak_free_part - partially unregister a previously registered object
901 * @ptr: pointer to the beginning or inside the object. This also
902 * represents the start of the range to be freed
903 * @size: size to be unregistered
904 *
905 * This function is called when only a part of a memory block is freed
906 * (usually from the bootmem allocator).
Catalin Marinas53238a62009-07-07 10:33:00 +0100907 */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100908void __ref kmemleak_free_part(const void *ptr, size_t size)
Catalin Marinas53238a62009-07-07 10:33:00 +0100909{
910 pr_debug("%s(0x%p)\n", __func__, ptr);
911
912 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
913 delete_object_part((unsigned long)ptr, size);
914 else if (atomic_read(&kmemleak_early_log))
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000915 log_early(KMEMLEAK_FREE_PART, ptr, size, 0);
Catalin Marinas53238a62009-07-07 10:33:00 +0100916}
917EXPORT_SYMBOL_GPL(kmemleak_free_part);
918
Catalin Marinasa2b6bf62010-07-19 11:54:17 +0100919/**
920 * kmemleak_not_leak - mark an allocated object as false positive
921 * @ptr: pointer to beginning of the object
922 *
923 * Calling this function on an object will cause the memory block to no longer
924 * be reported as leak and always be scanned.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100925 */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100926void __ref kmemleak_not_leak(const void *ptr)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100927{
928 pr_debug("%s(0x%p)\n", __func__, ptr);
929
930 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
931 make_gray_object((unsigned long)ptr);
932 else if (atomic_read(&kmemleak_early_log))
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000933 log_early(KMEMLEAK_NOT_LEAK, ptr, 0, 0);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100934}
935EXPORT_SYMBOL(kmemleak_not_leak);
936
Catalin Marinasa2b6bf62010-07-19 11:54:17 +0100937/**
938 * kmemleak_ignore - ignore an allocated object
939 * @ptr: pointer to beginning of the object
940 *
941 * Calling this function on an object will cause the memory block to be
942 * ignored (not scanned and not reported as a leak). This is usually done when
943 * it is known that the corresponding block is not a leak and does not contain
944 * any references to other allocated memory blocks.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100945 */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100946void __ref kmemleak_ignore(const void *ptr)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100947{
948 pr_debug("%s(0x%p)\n", __func__, ptr);
949
950 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
951 make_black_object((unsigned long)ptr);
952 else if (atomic_read(&kmemleak_early_log))
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000953 log_early(KMEMLEAK_IGNORE, ptr, 0, 0);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100954}
955EXPORT_SYMBOL(kmemleak_ignore);
956
Catalin Marinasa2b6bf62010-07-19 11:54:17 +0100957/**
958 * kmemleak_scan_area - limit the range to be scanned in an allocated object
959 * @ptr: pointer to beginning or inside the object. This also
960 * represents the start of the scan area
961 * @size: size of the scan area
962 * @gfp: kmalloc() flags used for kmemleak internal memory allocations
963 *
964 * This function is used when it is known that only certain parts of an object
965 * contain references to other objects. Kmemleak will only scan these areas
966 * reducing the number false negatives.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100967 */
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000968void __ref kmemleak_scan_area(const void *ptr, size_t size, gfp_t gfp)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100969{
970 pr_debug("%s(0x%p)\n", __func__, ptr);
971
972 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000973 add_scan_area((unsigned long)ptr, size, gfp);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100974 else if (atomic_read(&kmemleak_early_log))
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000975 log_early(KMEMLEAK_SCAN_AREA, ptr, size, 0);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100976}
977EXPORT_SYMBOL(kmemleak_scan_area);
978
Catalin Marinasa2b6bf62010-07-19 11:54:17 +0100979/**
980 * kmemleak_no_scan - do not scan an allocated object
981 * @ptr: pointer to beginning of the object
982 *
983 * This function notifies kmemleak not to scan the given memory block. Useful
984 * in situations where it is known that the given object does not contain any
985 * references to other objects. Kmemleak will not scan such objects reducing
986 * the number of false negatives.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100987 */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100988void __ref kmemleak_no_scan(const void *ptr)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100989{
990 pr_debug("%s(0x%p)\n", __func__, ptr);
991
992 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
993 object_no_scan((unsigned long)ptr);
994 else if (atomic_read(&kmemleak_early_log))
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000995 log_early(KMEMLEAK_NO_SCAN, ptr, 0, 0);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100996}
997EXPORT_SYMBOL(kmemleak_no_scan);
998
999/*
Catalin Marinas04609ccc2009-10-28 13:33:12 +00001000 * Update an object's checksum and return true if it was modified.
1001 */
1002static bool update_checksum(struct kmemleak_object *object)
1003{
1004 u32 old_csum = object->checksum;
1005
1006 if (!kmemcheck_is_obj_initialized(object->pointer, object->size))
1007 return false;
1008
1009 object->checksum = crc32(0, (void *)object->pointer, object->size);
1010 return object->checksum != old_csum;
1011}
1012
1013/*
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001014 * Memory scanning is a long process and it needs to be interruptable. This
Lucas De Marchi25985ed2011-03-30 22:57:33 -03001015 * function checks whether such interrupt condition occurred.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001016 */
1017static int scan_should_stop(void)
1018{
1019 if (!atomic_read(&kmemleak_enabled))
1020 return 1;
1021
1022 /*
1023 * This function may be called from either process or kthread context,
1024 * hence the need to check for both stop conditions.
1025 */
1026 if (current->mm)
1027 return signal_pending(current);
1028 else
1029 return kthread_should_stop();
1030
1031 return 0;
1032}
1033
1034/*
1035 * Scan a memory block (exclusive range) for valid pointers and add those
1036 * found to the gray list.
1037 */
1038static void scan_block(void *_start, void *_end,
Catalin Marinas4b8a9672009-07-07 10:32:56 +01001039 struct kmemleak_object *scanned, int allow_resched)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001040{
1041 unsigned long *ptr;
1042 unsigned long *start = PTR_ALIGN(_start, BYTES_PER_POINTER);
1043 unsigned long *end = _end - (BYTES_PER_POINTER - 1);
1044
1045 for (ptr = start; ptr < end; ptr++) {
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001046 struct kmemleak_object *object;
Pekka Enberg8e019362009-08-27 14:50:00 +01001047 unsigned long flags;
1048 unsigned long pointer;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001049
Catalin Marinas4b8a9672009-07-07 10:32:56 +01001050 if (allow_resched)
1051 cond_resched();
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001052 if (scan_should_stop())
1053 break;
1054
Pekka Enberg8e019362009-08-27 14:50:00 +01001055 /* don't scan uninitialized memory */
1056 if (!kmemcheck_is_obj_initialized((unsigned long)ptr,
1057 BYTES_PER_POINTER))
1058 continue;
1059
1060 pointer = *ptr;
1061
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001062 object = find_and_get_object(pointer, 1);
1063 if (!object)
1064 continue;
1065 if (object == scanned) {
1066 /* self referenced, ignore */
1067 put_object(object);
1068 continue;
1069 }
1070
1071 /*
1072 * Avoid the lockdep recursive warning on object->lock being
1073 * previously acquired in scan_object(). These locks are
1074 * enclosed by scan_mutex.
1075 */
1076 spin_lock_irqsave_nested(&object->lock, flags,
1077 SINGLE_DEPTH_NESTING);
1078 if (!color_white(object)) {
1079 /* non-orphan, ignored or new */
1080 spin_unlock_irqrestore(&object->lock, flags);
1081 put_object(object);
1082 continue;
1083 }
1084
1085 /*
1086 * Increase the object's reference count (number of pointers
1087 * to the memory block). If this count reaches the required
1088 * minimum, the object's color will become gray and it will be
1089 * added to the gray_list.
1090 */
1091 object->count++;
Catalin Marinas0587da42009-10-28 13:33:11 +00001092 if (color_gray(object)) {
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001093 list_add_tail(&object->gray_list, &gray_list);
Catalin Marinas0587da42009-10-28 13:33:11 +00001094 spin_unlock_irqrestore(&object->lock, flags);
1095 continue;
1096 }
1097
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001098 spin_unlock_irqrestore(&object->lock, flags);
Catalin Marinas0587da42009-10-28 13:33:11 +00001099 put_object(object);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001100 }
1101}
1102
1103/*
1104 * Scan a memory block corresponding to a kmemleak_object. A condition is
1105 * that object->use_count >= 1.
1106 */
1107static void scan_object(struct kmemleak_object *object)
1108{
1109 struct kmemleak_scan_area *area;
1110 struct hlist_node *elem;
1111 unsigned long flags;
1112
1113 /*
Uwe Kleine-König21ae2952009-10-07 15:21:09 +02001114 * Once the object->lock is acquired, the corresponding memory block
1115 * cannot be freed (the same lock is acquired in delete_object).
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001116 */
1117 spin_lock_irqsave(&object->lock, flags);
1118 if (object->flags & OBJECT_NO_SCAN)
1119 goto out;
1120 if (!(object->flags & OBJECT_ALLOCATED))
1121 /* already freed object */
1122 goto out;
Catalin Marinasaf986032009-08-27 14:29:12 +01001123 if (hlist_empty(&object->area_list)) {
1124 void *start = (void *)object->pointer;
1125 void *end = (void *)(object->pointer + object->size);
1126
1127 while (start < end && (object->flags & OBJECT_ALLOCATED) &&
1128 !(object->flags & OBJECT_NO_SCAN)) {
1129 scan_block(start, min(start + MAX_SCAN_SIZE, end),
1130 object, 0);
1131 start += MAX_SCAN_SIZE;
1132
1133 spin_unlock_irqrestore(&object->lock, flags);
1134 cond_resched();
1135 spin_lock_irqsave(&object->lock, flags);
1136 }
1137 } else
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001138 hlist_for_each_entry(area, elem, &object->area_list, node)
Catalin Marinasc017b4b2009-10-28 13:33:09 +00001139 scan_block((void *)area->start,
1140 (void *)(area->start + area->size),
1141 object, 0);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001142out:
1143 spin_unlock_irqrestore(&object->lock, flags);
1144}
1145
1146/*
Catalin Marinas04609ccc2009-10-28 13:33:12 +00001147 * Scan the objects already referenced (gray objects). More objects will be
1148 * referenced and, if there are no memory leaks, all the objects are scanned.
1149 */
1150static void scan_gray_list(void)
1151{
1152 struct kmemleak_object *object, *tmp;
1153
1154 /*
1155 * The list traversal is safe for both tail additions and removals
1156 * from inside the loop. The kmemleak objects cannot be freed from
1157 * outside the loop because their use_count was incremented.
1158 */
1159 object = list_entry(gray_list.next, typeof(*object), gray_list);
1160 while (&object->gray_list != &gray_list) {
1161 cond_resched();
1162
1163 /* may add new objects to the list */
1164 if (!scan_should_stop())
1165 scan_object(object);
1166
1167 tmp = list_entry(object->gray_list.next, typeof(*object),
1168 gray_list);
1169
1170 /* remove the object from the list and release it */
1171 list_del(&object->gray_list);
1172 put_object(object);
1173
1174 object = tmp;
1175 }
1176 WARN_ON(!list_empty(&gray_list));
1177}
1178
1179/*
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001180 * Scan data sections and all the referenced memory blocks allocated via the
1181 * kernel's standard allocators. This function must be called with the
1182 * scan_mutex held.
1183 */
1184static void kmemleak_scan(void)
1185{
1186 unsigned long flags;
Catalin Marinas04609ccc2009-10-28 13:33:12 +00001187 struct kmemleak_object *object;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001188 int i;
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001189 int new_leaks = 0;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001190
Catalin Marinasacf49682009-06-26 17:38:29 +01001191 jiffies_last_scan = jiffies;
1192
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001193 /* prepare the kmemleak_object's */
1194 rcu_read_lock();
1195 list_for_each_entry_rcu(object, &object_list, object_list) {
1196 spin_lock_irqsave(&object->lock, flags);
1197#ifdef DEBUG
1198 /*
1199 * With a few exceptions there should be a maximum of
1200 * 1 reference to any object at this point.
1201 */
1202 if (atomic_read(&object->use_count) > 1) {
Joe Perchesae281062009-06-23 14:40:26 +01001203 pr_debug("object->use_count = %d\n",
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001204 atomic_read(&object->use_count));
1205 dump_object_info(object);
1206 }
1207#endif
1208 /* reset the reference count (whiten the object) */
1209 object->count = 0;
1210 if (color_gray(object) && get_object(object))
1211 list_add_tail(&object->gray_list, &gray_list);
1212
1213 spin_unlock_irqrestore(&object->lock, flags);
1214 }
1215 rcu_read_unlock();
1216
1217 /* data/bss scanning */
Catalin Marinas4b8a9672009-07-07 10:32:56 +01001218 scan_block(_sdata, _edata, NULL, 1);
1219 scan_block(__bss_start, __bss_stop, NULL, 1);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001220
1221#ifdef CONFIG_SMP
1222 /* per-cpu sections scanning */
1223 for_each_possible_cpu(i)
1224 scan_block(__per_cpu_start + per_cpu_offset(i),
Catalin Marinas4b8a9672009-07-07 10:32:56 +01001225 __per_cpu_end + per_cpu_offset(i), NULL, 1);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001226#endif
1227
1228 /*
1229 * Struct page scanning for each node. The code below is not yet safe
1230 * with MEMORY_HOTPLUG.
1231 */
1232 for_each_online_node(i) {
1233 pg_data_t *pgdat = NODE_DATA(i);
1234 unsigned long start_pfn = pgdat->node_start_pfn;
1235 unsigned long end_pfn = start_pfn + pgdat->node_spanned_pages;
1236 unsigned long pfn;
1237
1238 for (pfn = start_pfn; pfn < end_pfn; pfn++) {
1239 struct page *page;
1240
1241 if (!pfn_valid(pfn))
1242 continue;
1243 page = pfn_to_page(pfn);
1244 /* only scan if page is in use */
1245 if (page_count(page) == 0)
1246 continue;
Catalin Marinas4b8a9672009-07-07 10:32:56 +01001247 scan_block(page, page + 1, NULL, 1);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001248 }
1249 }
1250
1251 /*
Catalin Marinas43ed5d62009-09-01 11:12:44 +01001252 * Scanning the task stacks (may introduce false negatives).
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001253 */
1254 if (kmemleak_stack_scan) {
Catalin Marinas43ed5d62009-09-01 11:12:44 +01001255 struct task_struct *p, *g;
1256
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001257 read_lock(&tasklist_lock);
Catalin Marinas43ed5d62009-09-01 11:12:44 +01001258 do_each_thread(g, p) {
1259 scan_block(task_stack_page(p), task_stack_page(p) +
1260 THREAD_SIZE, NULL, 0);
1261 } while_each_thread(g, p);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001262 read_unlock(&tasklist_lock);
1263 }
1264
1265 /*
1266 * Scan the objects already referenced from the sections scanned
Catalin Marinas04609ccc2009-10-28 13:33:12 +00001267 * above.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001268 */
Catalin Marinas04609ccc2009-10-28 13:33:12 +00001269 scan_gray_list();
Catalin Marinas25873622009-07-07 10:32:58 +01001270
1271 /*
Catalin Marinas04609ccc2009-10-28 13:33:12 +00001272 * Check for new or unreferenced objects modified since the previous
1273 * scan and color them gray until the next scan.
Catalin Marinas25873622009-07-07 10:32:58 +01001274 */
1275 rcu_read_lock();
1276 list_for_each_entry_rcu(object, &object_list, object_list) {
1277 spin_lock_irqsave(&object->lock, flags);
Catalin Marinas04609ccc2009-10-28 13:33:12 +00001278 if (color_white(object) && (object->flags & OBJECT_ALLOCATED)
1279 && update_checksum(object) && get_object(object)) {
1280 /* color it gray temporarily */
1281 object->count = object->min_count;
Catalin Marinas25873622009-07-07 10:32:58 +01001282 list_add_tail(&object->gray_list, &gray_list);
1283 }
1284 spin_unlock_irqrestore(&object->lock, flags);
1285 }
1286 rcu_read_unlock();
1287
Catalin Marinas04609ccc2009-10-28 13:33:12 +00001288 /*
1289 * Re-scan the gray list for modified unreferenced objects.
1290 */
1291 scan_gray_list();
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001292
1293 /*
Catalin Marinas04609ccc2009-10-28 13:33:12 +00001294 * If scanning was stopped do not report any new unreferenced objects.
Catalin Marinas17bb9e02009-06-29 17:13:56 +01001295 */
Catalin Marinas04609ccc2009-10-28 13:33:12 +00001296 if (scan_should_stop())
Catalin Marinas17bb9e02009-06-29 17:13:56 +01001297 return;
1298
1299 /*
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001300 * Scanning result reporting.
1301 */
1302 rcu_read_lock();
1303 list_for_each_entry_rcu(object, &object_list, object_list) {
1304 spin_lock_irqsave(&object->lock, flags);
1305 if (unreferenced_object(object) &&
1306 !(object->flags & OBJECT_REPORTED)) {
1307 object->flags |= OBJECT_REPORTED;
1308 new_leaks++;
1309 }
1310 spin_unlock_irqrestore(&object->lock, flags);
1311 }
1312 rcu_read_unlock();
1313
1314 if (new_leaks)
1315 pr_info("%d new suspected memory leaks (see "
1316 "/sys/kernel/debug/kmemleak)\n", new_leaks);
1317
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001318}
1319
1320/*
1321 * Thread function performing automatic memory scanning. Unreferenced objects
1322 * at the end of a memory scan are reported but only the first time.
1323 */
1324static int kmemleak_scan_thread(void *arg)
1325{
1326 static int first_run = 1;
1327
Joe Perchesae281062009-06-23 14:40:26 +01001328 pr_info("Automatic memory scanning thread started\n");
Catalin Marinasbf2a76b2009-07-07 10:32:55 +01001329 set_user_nice(current, 10);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001330
1331 /*
1332 * Wait before the first scan to allow the system to fully initialize.
1333 */
1334 if (first_run) {
1335 first_run = 0;
1336 ssleep(SECS_FIRST_SCAN);
1337 }
1338
1339 while (!kthread_should_stop()) {
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001340 signed long timeout = jiffies_scan_wait;
1341
1342 mutex_lock(&scan_mutex);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001343 kmemleak_scan();
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001344 mutex_unlock(&scan_mutex);
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001345
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001346 /* wait before the next scan */
1347 while (timeout && !kthread_should_stop())
1348 timeout = schedule_timeout_interruptible(timeout);
1349 }
1350
Joe Perchesae281062009-06-23 14:40:26 +01001351 pr_info("Automatic memory scanning thread ended\n");
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001352
1353 return 0;
1354}
1355
1356/*
1357 * Start the automatic memory scanning thread. This function must be called
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001358 * with the scan_mutex held.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001359 */
Luis R. Rodriguez7eb0d5e2009-09-08 17:31:45 +01001360static void start_scan_thread(void)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001361{
1362 if (scan_thread)
1363 return;
1364 scan_thread = kthread_run(kmemleak_scan_thread, NULL, "kmemleak");
1365 if (IS_ERR(scan_thread)) {
Joe Perchesae281062009-06-23 14:40:26 +01001366 pr_warning("Failed to create the scan thread\n");
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001367 scan_thread = NULL;
1368 }
1369}
1370
1371/*
1372 * Stop the automatic memory scanning thread. This function must be called
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001373 * with the scan_mutex held.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001374 */
Luis R. Rodriguez7eb0d5e2009-09-08 17:31:45 +01001375static void stop_scan_thread(void)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001376{
1377 if (scan_thread) {
1378 kthread_stop(scan_thread);
1379 scan_thread = NULL;
1380 }
1381}
1382
1383/*
1384 * Iterate over the object_list and return the first valid object at or after
1385 * the required position with its use_count incremented. The function triggers
1386 * a memory scanning when the pos argument points to the first position.
1387 */
1388static void *kmemleak_seq_start(struct seq_file *seq, loff_t *pos)
1389{
1390 struct kmemleak_object *object;
1391 loff_t n = *pos;
Catalin Marinasb87324d2009-07-07 10:32:58 +01001392 int err;
1393
1394 err = mutex_lock_interruptible(&scan_mutex);
1395 if (err < 0)
1396 return ERR_PTR(err);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001397
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001398 rcu_read_lock();
1399 list_for_each_entry_rcu(object, &object_list, object_list) {
1400 if (n-- > 0)
1401 continue;
1402 if (get_object(object))
1403 goto out;
1404 }
1405 object = NULL;
1406out:
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001407 return object;
1408}
1409
1410/*
1411 * Return the next object in the object_list. The function decrements the
1412 * use_count of the previous object and increases that of the next one.
1413 */
1414static void *kmemleak_seq_next(struct seq_file *seq, void *v, loff_t *pos)
1415{
1416 struct kmemleak_object *prev_obj = v;
1417 struct kmemleak_object *next_obj = NULL;
1418 struct list_head *n = &prev_obj->object_list;
1419
1420 ++(*pos);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001421
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001422 list_for_each_continue_rcu(n, &object_list) {
Catalin Marinas52c3ce42011-04-27 16:44:26 +01001423 struct kmemleak_object *obj =
1424 list_entry(n, struct kmemleak_object, object_list);
1425 if (get_object(obj)) {
1426 next_obj = obj;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001427 break;
Catalin Marinas52c3ce42011-04-27 16:44:26 +01001428 }
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001429 }
Catalin Marinas288c8572009-07-07 10:32:57 +01001430
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001431 put_object(prev_obj);
1432 return next_obj;
1433}
1434
1435/*
1436 * Decrement the use_count of the last object required, if any.
1437 */
1438static void kmemleak_seq_stop(struct seq_file *seq, void *v)
1439{
Catalin Marinasb87324d2009-07-07 10:32:58 +01001440 if (!IS_ERR(v)) {
1441 /*
1442 * kmemleak_seq_start may return ERR_PTR if the scan_mutex
1443 * waiting was interrupted, so only release it if !IS_ERR.
1444 */
Catalin Marinasf5886c72009-07-29 16:26:57 +01001445 rcu_read_unlock();
Catalin Marinasb87324d2009-07-07 10:32:58 +01001446 mutex_unlock(&scan_mutex);
1447 if (v)
1448 put_object(v);
1449 }
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001450}
1451
1452/*
1453 * Print the information for an unreferenced object to the seq file.
1454 */
1455static int kmemleak_seq_show(struct seq_file *seq, void *v)
1456{
1457 struct kmemleak_object *object = v;
1458 unsigned long flags;
1459
1460 spin_lock_irqsave(&object->lock, flags);
Catalin Marinas288c8572009-07-07 10:32:57 +01001461 if ((object->flags & OBJECT_REPORTED) && unreferenced_object(object))
Catalin Marinas17bb9e02009-06-29 17:13:56 +01001462 print_unreferenced(seq, object);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001463 spin_unlock_irqrestore(&object->lock, flags);
1464 return 0;
1465}
1466
1467static const struct seq_operations kmemleak_seq_ops = {
1468 .start = kmemleak_seq_start,
1469 .next = kmemleak_seq_next,
1470 .stop = kmemleak_seq_stop,
1471 .show = kmemleak_seq_show,
1472};
1473
1474static int kmemleak_open(struct inode *inode, struct file *file)
1475{
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001476 if (!atomic_read(&kmemleak_enabled))
1477 return -EBUSY;
1478
Catalin Marinasb87324d2009-07-07 10:32:58 +01001479 return seq_open(file, &kmemleak_seq_ops);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001480}
1481
1482static int kmemleak_release(struct inode *inode, struct file *file)
1483{
Catalin Marinasb87324d2009-07-07 10:32:58 +01001484 return seq_release(inode, file);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001485}
1486
Catalin Marinas189d84e2009-08-27 14:29:15 +01001487static int dump_str_object_info(const char *str)
1488{
1489 unsigned long flags;
1490 struct kmemleak_object *object;
1491 unsigned long addr;
1492
1493 addr= simple_strtoul(str, NULL, 0);
1494 object = find_and_get_object(addr, 0);
1495 if (!object) {
1496 pr_info("Unknown object at 0x%08lx\n", addr);
1497 return -EINVAL;
1498 }
1499
1500 spin_lock_irqsave(&object->lock, flags);
1501 dump_object_info(object);
1502 spin_unlock_irqrestore(&object->lock, flags);
1503
1504 put_object(object);
1505 return 0;
1506}
1507
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001508/*
Luis R. Rodriguez30b37102009-09-04 17:44:51 -07001509 * We use grey instead of black to ensure we can do future scans on the same
1510 * objects. If we did not do future scans these black objects could
1511 * potentially contain references to newly allocated objects in the future and
1512 * we'd end up with false positives.
1513 */
1514static void kmemleak_clear(void)
1515{
1516 struct kmemleak_object *object;
1517 unsigned long flags;
1518
1519 rcu_read_lock();
1520 list_for_each_entry_rcu(object, &object_list, object_list) {
1521 spin_lock_irqsave(&object->lock, flags);
1522 if ((object->flags & OBJECT_REPORTED) &&
1523 unreferenced_object(object))
Luis R. Rodrigueza1084c82009-09-04 17:44:52 -07001524 __paint_it(object, KMEMLEAK_GREY);
Luis R. Rodriguez30b37102009-09-04 17:44:51 -07001525 spin_unlock_irqrestore(&object->lock, flags);
1526 }
1527 rcu_read_unlock();
1528}
1529
1530/*
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001531 * File write operation to configure kmemleak at run-time. The following
1532 * commands can be written to the /sys/kernel/debug/kmemleak file:
1533 * off - disable kmemleak (irreversible)
1534 * stack=on - enable the task stacks scanning
1535 * stack=off - disable the tasks stacks scanning
1536 * scan=on - start the automatic memory scanning thread
1537 * scan=off - stop the automatic memory scanning thread
1538 * scan=... - set the automatic memory scanning period in seconds (0 to
1539 * disable it)
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001540 * scan - trigger a memory scan
Luis R. Rodriguez30b37102009-09-04 17:44:51 -07001541 * clear - mark all current reported unreferenced kmemleak objects as
1542 * grey to ignore printing them
Catalin Marinas189d84e2009-08-27 14:29:15 +01001543 * dump=... - dump information about the object found at the given address
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001544 */
1545static ssize_t kmemleak_write(struct file *file, const char __user *user_buf,
1546 size_t size, loff_t *ppos)
1547{
1548 char buf[64];
1549 int buf_size;
Catalin Marinasb87324d2009-07-07 10:32:58 +01001550 int ret;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001551
1552 buf_size = min(size, (sizeof(buf) - 1));
1553 if (strncpy_from_user(buf, user_buf, buf_size) < 0)
1554 return -EFAULT;
1555 buf[buf_size] = 0;
1556
Catalin Marinasb87324d2009-07-07 10:32:58 +01001557 ret = mutex_lock_interruptible(&scan_mutex);
1558 if (ret < 0)
1559 return ret;
1560
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001561 if (strncmp(buf, "off", 3) == 0)
1562 kmemleak_disable();
1563 else if (strncmp(buf, "stack=on", 8) == 0)
1564 kmemleak_stack_scan = 1;
1565 else if (strncmp(buf, "stack=off", 9) == 0)
1566 kmemleak_stack_scan = 0;
1567 else if (strncmp(buf, "scan=on", 7) == 0)
1568 start_scan_thread();
1569 else if (strncmp(buf, "scan=off", 8) == 0)
1570 stop_scan_thread();
1571 else if (strncmp(buf, "scan=", 5) == 0) {
1572 unsigned long secs;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001573
Catalin Marinasb87324d2009-07-07 10:32:58 +01001574 ret = strict_strtoul(buf + 5, 0, &secs);
1575 if (ret < 0)
1576 goto out;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001577 stop_scan_thread();
1578 if (secs) {
1579 jiffies_scan_wait = msecs_to_jiffies(secs * 1000);
1580 start_scan_thread();
1581 }
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001582 } else if (strncmp(buf, "scan", 4) == 0)
1583 kmemleak_scan();
Luis R. Rodriguez30b37102009-09-04 17:44:51 -07001584 else if (strncmp(buf, "clear", 5) == 0)
1585 kmemleak_clear();
Catalin Marinas189d84e2009-08-27 14:29:15 +01001586 else if (strncmp(buf, "dump=", 5) == 0)
1587 ret = dump_str_object_info(buf + 5);
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001588 else
Catalin Marinasb87324d2009-07-07 10:32:58 +01001589 ret = -EINVAL;
1590
1591out:
1592 mutex_unlock(&scan_mutex);
1593 if (ret < 0)
1594 return ret;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001595
1596 /* ignore the rest of the buffer, only one command at a time */
1597 *ppos += size;
1598 return size;
1599}
1600
1601static const struct file_operations kmemleak_fops = {
1602 .owner = THIS_MODULE,
1603 .open = kmemleak_open,
1604 .read = seq_read,
1605 .write = kmemleak_write,
1606 .llseek = seq_lseek,
1607 .release = kmemleak_release,
1608};
1609
1610/*
1611 * Perform the freeing of the kmemleak internal objects after waiting for any
1612 * current memory scan to complete.
1613 */
Catalin Marinas179a8102009-09-07 10:14:42 +01001614static void kmemleak_do_cleanup(struct work_struct *work)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001615{
1616 struct kmemleak_object *object;
1617
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001618 mutex_lock(&scan_mutex);
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001619 stop_scan_thread();
1620
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001621 rcu_read_lock();
1622 list_for_each_entry_rcu(object, &object_list, object_list)
Catalin Marinas53238a62009-07-07 10:33:00 +01001623 delete_object_full(object->pointer);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001624 rcu_read_unlock();
1625 mutex_unlock(&scan_mutex);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001626}
1627
Catalin Marinas179a8102009-09-07 10:14:42 +01001628static DECLARE_WORK(cleanup_work, kmemleak_do_cleanup);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001629
1630/*
1631 * Disable kmemleak. No memory allocation/freeing will be traced once this
1632 * function is called. Disabling kmemleak is an irreversible operation.
1633 */
1634static void kmemleak_disable(void)
1635{
1636 /* atomically check whether it was already invoked */
1637 if (atomic_cmpxchg(&kmemleak_error, 0, 1))
1638 return;
1639
1640 /* stop any memory operation tracing */
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001641 atomic_set(&kmemleak_enabled, 0);
1642
1643 /* check whether it is too early for a kernel thread */
1644 if (atomic_read(&kmemleak_initialized))
Catalin Marinas179a8102009-09-07 10:14:42 +01001645 schedule_work(&cleanup_work);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001646
1647 pr_info("Kernel memory leak detector disabled\n");
1648}
1649
1650/*
1651 * Allow boot-time kmemleak disabling (enabled by default).
1652 */
1653static int kmemleak_boot_config(char *str)
1654{
1655 if (!str)
1656 return -EINVAL;
1657 if (strcmp(str, "off") == 0)
1658 kmemleak_disable();
Jason Baronab0155a2010-07-19 11:54:17 +01001659 else if (strcmp(str, "on") == 0)
1660 kmemleak_skip_disable = 1;
1661 else
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001662 return -EINVAL;
1663 return 0;
1664}
1665early_param("kmemleak", kmemleak_boot_config);
1666
Catalin Marinas5f790202011-09-28 12:17:03 +01001667static void __init print_log_trace(struct early_log *log)
1668{
1669 struct stack_trace trace;
1670
1671 trace.nr_entries = log->trace_len;
1672 trace.entries = log->trace;
1673
1674 pr_notice("Early log backtrace:\n");
1675 print_stack_trace(&trace, 2);
1676}
1677
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001678/*
Catalin Marinas20301172009-06-17 18:29:04 +01001679 * Kmemleak initialization.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001680 */
1681void __init kmemleak_init(void)
1682{
1683 int i;
1684 unsigned long flags;
1685
Jason Baronab0155a2010-07-19 11:54:17 +01001686#ifdef CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF
1687 if (!kmemleak_skip_disable) {
1688 kmemleak_disable();
1689 return;
1690 }
1691#endif
1692
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001693 jiffies_min_age = msecs_to_jiffies(MSECS_MIN_AGE);
1694 jiffies_scan_wait = msecs_to_jiffies(SECS_SCAN_WAIT * 1000);
1695
1696 object_cache = KMEM_CACHE(kmemleak_object, SLAB_NOLEAKTRACE);
1697 scan_area_cache = KMEM_CACHE(kmemleak_scan_area, SLAB_NOLEAKTRACE);
1698 INIT_PRIO_TREE_ROOT(&object_tree_root);
1699
Catalin Marinasb6693002011-09-28 17:22:56 +01001700 if (crt_early_log >= ARRAY_SIZE(early_log))
1701 pr_warning("Early log buffer exceeded (%d), please increase "
1702 "DEBUG_KMEMLEAK_EARLY_LOG_SIZE\n", crt_early_log);
1703
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001704 /* the kernel is still in UP mode, so disabling the IRQs is enough */
1705 local_irq_save(flags);
Catalin Marinasb6693002011-09-28 17:22:56 +01001706 atomic_set(&kmemleak_early_log, 0);
1707 if (atomic_read(&kmemleak_error)) {
1708 local_irq_restore(flags);
1709 return;
1710 } else
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001711 atomic_set(&kmemleak_enabled, 1);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001712 local_irq_restore(flags);
1713
1714 /*
1715 * This is the point where tracking allocations is safe. Automatic
1716 * scanning is started during the late initcall. Add the early logged
1717 * callbacks to the kmemleak infrastructure.
1718 */
1719 for (i = 0; i < crt_early_log; i++) {
1720 struct early_log *log = &early_log[i];
1721
1722 switch (log->op_type) {
1723 case KMEMLEAK_ALLOC:
Catalin Marinasfd678962009-08-27 14:29:17 +01001724 early_alloc(log);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001725 break;
1726 case KMEMLEAK_FREE:
1727 kmemleak_free(log->ptr);
1728 break;
Catalin Marinas53238a62009-07-07 10:33:00 +01001729 case KMEMLEAK_FREE_PART:
1730 kmemleak_free_part(log->ptr, log->size);
1731 break;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001732 case KMEMLEAK_NOT_LEAK:
1733 kmemleak_not_leak(log->ptr);
1734 break;
1735 case KMEMLEAK_IGNORE:
1736 kmemleak_ignore(log->ptr);
1737 break;
1738 case KMEMLEAK_SCAN_AREA:
Catalin Marinasc017b4b2009-10-28 13:33:09 +00001739 kmemleak_scan_area(log->ptr, log->size, GFP_KERNEL);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001740 break;
1741 case KMEMLEAK_NO_SCAN:
1742 kmemleak_no_scan(log->ptr);
1743 break;
1744 default:
Catalin Marinas5f790202011-09-28 12:17:03 +01001745 kmemleak_warn("Unknown early log operation: %d\n",
1746 log->op_type);
1747 }
1748
1749 if (atomic_read(&kmemleak_warning)) {
1750 print_log_trace(log);
1751 atomic_set(&kmemleak_warning, 0);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001752 }
1753 }
1754}
1755
1756/*
1757 * Late initialization function.
1758 */
1759static int __init kmemleak_late_init(void)
1760{
1761 struct dentry *dentry;
1762
1763 atomic_set(&kmemleak_initialized, 1);
1764
1765 if (atomic_read(&kmemleak_error)) {
1766 /*
Lucas De Marchi25985ed2011-03-30 22:57:33 -03001767 * Some error occurred and kmemleak was disabled. There is a
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001768 * small chance that kmemleak_disable() was called immediately
1769 * after setting kmemleak_initialized and we may end up with
1770 * two clean-up threads but serialized by scan_mutex.
1771 */
Catalin Marinas179a8102009-09-07 10:14:42 +01001772 schedule_work(&cleanup_work);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001773 return -ENOMEM;
1774 }
1775
1776 dentry = debugfs_create_file("kmemleak", S_IRUGO, NULL, NULL,
1777 &kmemleak_fops);
1778 if (!dentry)
Joe Perchesae281062009-06-23 14:40:26 +01001779 pr_warning("Failed to create the debugfs kmemleak file\n");
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001780 mutex_lock(&scan_mutex);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001781 start_scan_thread();
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001782 mutex_unlock(&scan_mutex);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001783
1784 pr_info("Kernel memory leak detector initialized\n");
1785
1786 return 0;
1787}
1788late_initcall(kmemleak_late_init);