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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>
Laura Abbott029aeff2011-11-15 23:49:09 +0000103#include <linux/memory_hotplug.h>
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100104
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 */
Catalin Marinas6ae4bd12011-01-27 10:30:26 +0000117#define gfp_kmemleak_mask(gfp) (((gfp) & (GFP_KERNEL | GFP_ATOMIC)) | \
118 __GFP_NORETRY | __GFP_NOMEMALLOC | \
119 __GFP_NOWARN)
Catalin Marinas216c04b2009-06-17 18:29:02 +0100120
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100121/* scanning area inside a memory block */
122struct kmemleak_scan_area {
123 struct hlist_node node;
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000124 unsigned long start;
125 size_t size;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100126};
127
Luis R. Rodrigueza1084c82009-09-04 17:44:52 -0700128#define KMEMLEAK_GREY 0
129#define KMEMLEAK_BLACK -1
130
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100131/*
132 * Structure holding the metadata for each allocated memory block.
133 * Modifications to such objects should be made while holding the
134 * object->lock. Insertions or deletions from object_list, gray_list or
135 * tree_node are already protected by the corresponding locks or mutex (see
136 * the notes on locking above). These objects are reference-counted
137 * (use_count) and freed using the RCU mechanism.
138 */
139struct kmemleak_object {
140 spinlock_t lock;
141 unsigned long flags; /* object status flags */
142 struct list_head object_list;
143 struct list_head gray_list;
144 struct prio_tree_node tree_node;
145 struct rcu_head rcu; /* object_list lockless traversal */
146 /* object usage count; object freed when use_count == 0 */
147 atomic_t use_count;
148 unsigned long pointer;
149 size_t size;
150 /* minimum number of a pointers found before it is considered leak */
151 int min_count;
152 /* the total number of pointers found pointing to this object */
153 int count;
Catalin Marinas04609ccc2009-10-28 13:33:12 +0000154 /* checksum for detecting modified objects */
155 u32 checksum;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100156 /* memory ranges to be scanned inside an object (empty for all) */
157 struct hlist_head area_list;
158 unsigned long trace[MAX_TRACE];
159 unsigned int trace_len;
160 unsigned long jiffies; /* creation timestamp */
161 pid_t pid; /* pid of the current task */
162 char comm[TASK_COMM_LEN]; /* executable name */
163};
164
165/* flag representing the memory block allocation status */
166#define OBJECT_ALLOCATED (1 << 0)
167/* flag set after the first reporting of an unreference object */
168#define OBJECT_REPORTED (1 << 1)
169/* flag set to not scan the object */
170#define OBJECT_NO_SCAN (1 << 2)
171
Sergey Senozhatsky0494e082009-08-27 14:29:18 +0100172/* number of bytes to print per line; must be 16 or 32 */
173#define HEX_ROW_SIZE 16
174/* number of bytes to print at a time (1, 2, 4, 8) */
175#define HEX_GROUP_SIZE 1
176/* include ASCII after the hex output */
177#define HEX_ASCII 1
178/* max number of lines to be printed */
179#define HEX_MAX_LINES 2
180
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100181/* the list of all allocated objects */
182static LIST_HEAD(object_list);
183/* the list of gray-colored objects (see color_gray comment below) */
184static LIST_HEAD(gray_list);
185/* prio search tree for object boundaries */
186static struct prio_tree_root object_tree_root;
187/* rw_lock protecting the access to object_list and prio_tree_root */
188static DEFINE_RWLOCK(kmemleak_lock);
189
190/* allocation caches for kmemleak internal data */
191static struct kmem_cache *object_cache;
192static struct kmem_cache *scan_area_cache;
193
194/* set if tracing memory operations is enabled */
195static atomic_t kmemleak_enabled = ATOMIC_INIT(0);
196/* set in the late_initcall if there were no errors */
197static atomic_t kmemleak_initialized = ATOMIC_INIT(0);
198/* enables or disables early logging of the memory operations */
199static atomic_t kmemleak_early_log = ATOMIC_INIT(1);
Catalin Marinas5f790202011-09-28 12:17:03 +0100200/* set if a kmemleak warning was issued */
201static atomic_t kmemleak_warning = ATOMIC_INIT(0);
202/* set if a fatal kmemleak error has occurred */
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100203static atomic_t kmemleak_error = ATOMIC_INIT(0);
204
205/* minimum and maximum address that may be valid pointers */
206static unsigned long min_addr = ULONG_MAX;
207static unsigned long max_addr;
208
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100209static struct task_struct *scan_thread;
Catalin Marinasacf49682009-06-26 17:38:29 +0100210/* used to avoid reporting of recently allocated objects */
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100211static unsigned long jiffies_min_age;
Catalin Marinasacf49682009-06-26 17:38:29 +0100212static unsigned long jiffies_last_scan;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100213/* delay between automatic memory scannings */
214static signed long jiffies_scan_wait;
215/* enables or disables the task stacks scanning */
Catalin Marinase0a2a162009-06-26 17:38:25 +0100216static int kmemleak_stack_scan = 1;
Catalin Marinas4698c1f2009-06-26 17:38:27 +0100217/* protects the memory scanning, parameters and debug/kmemleak file access */
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100218static DEFINE_MUTEX(scan_mutex);
Jason Baronab0155a2010-07-19 11:54:17 +0100219/* setting kmemleak=on, will set this var, skipping the disable */
220static int kmemleak_skip_disable;
221
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100222
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100223/*
Catalin Marinas20301172009-06-17 18:29:04 +0100224 * Early object allocation/freeing logging. Kmemleak is initialized after the
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100225 * kernel allocator. However, both the kernel allocator and kmemleak may
Catalin Marinas20301172009-06-17 18:29:04 +0100226 * allocate memory blocks which need to be tracked. Kmemleak defines an
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100227 * arbitrary buffer to hold the allocation/freeing information before it is
228 * fully initialized.
229 */
230
231/* kmemleak operation type for early logging */
232enum {
233 KMEMLEAK_ALLOC,
Catalin Marinasf528f0b2011-09-26 17:12:53 +0100234 KMEMLEAK_ALLOC_PERCPU,
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100235 KMEMLEAK_FREE,
Catalin Marinas53238a62009-07-07 10:33:00 +0100236 KMEMLEAK_FREE_PART,
Catalin Marinasf528f0b2011-09-26 17:12:53 +0100237 KMEMLEAK_FREE_PERCPU,
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100238 KMEMLEAK_NOT_LEAK,
239 KMEMLEAK_IGNORE,
240 KMEMLEAK_SCAN_AREA,
241 KMEMLEAK_NO_SCAN
242};
243
244/*
245 * Structure holding the information passed to kmemleak callbacks during the
246 * early logging.
247 */
248struct early_log {
249 int op_type; /* kmemleak operation type */
250 const void *ptr; /* allocated/freed memory block */
251 size_t size; /* memory block size */
252 int min_count; /* minimum reference count */
Catalin Marinasfd678962009-08-27 14:29:17 +0100253 unsigned long trace[MAX_TRACE]; /* stack trace */
254 unsigned int trace_len; /* stack trace length */
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100255};
256
257/* early logging buffer and current position */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100258static struct early_log
259 early_log[CONFIG_DEBUG_KMEMLEAK_EARLY_LOG_SIZE] __initdata;
260static int crt_early_log __initdata;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100261
262static void kmemleak_disable(void);
263
264/*
265 * Print a warning and dump the stack trace.
266 */
Catalin Marinas5f790202011-09-28 12:17:03 +0100267#define kmemleak_warn(x...) do { \
268 pr_warning(x); \
269 dump_stack(); \
270 atomic_set(&kmemleak_warning, 1); \
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100271} while (0)
272
273/*
Lucas De Marchi25985ed2011-03-30 22:57:33 -0300274 * Macro invoked when a serious kmemleak condition occurred and cannot be
Catalin Marinas20301172009-06-17 18:29:04 +0100275 * recovered from. Kmemleak will be disabled and further allocation/freeing
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100276 * tracing no longer available.
277 */
Catalin Marinas000814f2009-06-17 18:29:03 +0100278#define kmemleak_stop(x...) do { \
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100279 kmemleak_warn(x); \
280 kmemleak_disable(); \
281} while (0)
282
283/*
Sergey Senozhatsky0494e082009-08-27 14:29:18 +0100284 * Printing of the objects hex dump to the seq file. The number of lines to be
285 * printed is limited to HEX_MAX_LINES to prevent seq file spamming. The
286 * actual number of printed bytes depends on HEX_ROW_SIZE. It must be called
287 * with the object->lock held.
288 */
289static void hex_dump_object(struct seq_file *seq,
290 struct kmemleak_object *object)
291{
292 const u8 *ptr = (const u8 *)object->pointer;
293 int i, len, remaining;
294 unsigned char linebuf[HEX_ROW_SIZE * 5];
295
296 /* limit the number of lines to HEX_MAX_LINES */
297 remaining = len =
298 min(object->size, (size_t)(HEX_MAX_LINES * HEX_ROW_SIZE));
299
300 seq_printf(seq, " hex dump (first %d bytes):\n", len);
301 for (i = 0; i < len; i += HEX_ROW_SIZE) {
302 int linelen = min(remaining, HEX_ROW_SIZE);
303
304 remaining -= HEX_ROW_SIZE;
305 hex_dump_to_buffer(ptr + i, linelen, HEX_ROW_SIZE,
306 HEX_GROUP_SIZE, linebuf, sizeof(linebuf),
307 HEX_ASCII);
308 seq_printf(seq, " %s\n", linebuf);
309 }
310}
311
312/*
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100313 * Object colors, encoded with count and min_count:
314 * - white - orphan object, not enough references to it (count < min_count)
315 * - gray - not orphan, not marked as false positive (min_count == 0) or
316 * sufficient references to it (count >= min_count)
317 * - black - ignore, it doesn't contain references (e.g. text section)
318 * (min_count == -1). No function defined for this color.
319 * Newly created objects don't have any color assigned (object->count == -1)
320 * before the next memory scan when they become white.
321 */
Luis R. Rodriguez4a558dd2009-09-08 16:34:50 +0100322static bool color_white(const struct kmemleak_object *object)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100323{
Luis R. Rodrigueza1084c82009-09-04 17:44:52 -0700324 return object->count != KMEMLEAK_BLACK &&
325 object->count < object->min_count;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100326}
327
Luis R. Rodriguez4a558dd2009-09-08 16:34:50 +0100328static bool color_gray(const struct kmemleak_object *object)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100329{
Luis R. Rodrigueza1084c82009-09-04 17:44:52 -0700330 return object->min_count != KMEMLEAK_BLACK &&
331 object->count >= object->min_count;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100332}
333
334/*
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100335 * Objects are considered unreferenced only if their color is white, they have
336 * not be deleted and have a minimum age to avoid false positives caused by
337 * pointers temporarily stored in CPU registers.
338 */
Luis R. Rodriguez4a558dd2009-09-08 16:34:50 +0100339static bool unreferenced_object(struct kmemleak_object *object)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100340{
Catalin Marinas04609ccc2009-10-28 13:33:12 +0000341 return (color_white(object) && object->flags & OBJECT_ALLOCATED) &&
Catalin Marinasacf49682009-06-26 17:38:29 +0100342 time_before_eq(object->jiffies + jiffies_min_age,
343 jiffies_last_scan);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100344}
345
346/*
Catalin Marinasbab4a342009-06-26 17:38:26 +0100347 * Printing of the unreferenced objects information to the seq file. The
348 * print_unreferenced function must be called with the object->lock held.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100349 */
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100350static void print_unreferenced(struct seq_file *seq,
351 struct kmemleak_object *object)
352{
353 int i;
Catalin Marinasfefdd332009-10-28 13:33:12 +0000354 unsigned int msecs_age = jiffies_to_msecs(jiffies - object->jiffies);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100355
Catalin Marinasbab4a342009-06-26 17:38:26 +0100356 seq_printf(seq, "unreferenced object 0x%08lx (size %zu):\n",
357 object->pointer, object->size);
Catalin Marinasfefdd332009-10-28 13:33:12 +0000358 seq_printf(seq, " comm \"%s\", pid %d, jiffies %lu (age %d.%03ds)\n",
359 object->comm, object->pid, object->jiffies,
360 msecs_age / 1000, msecs_age % 1000);
Sergey Senozhatsky0494e082009-08-27 14:29:18 +0100361 hex_dump_object(seq, object);
Catalin Marinasbab4a342009-06-26 17:38:26 +0100362 seq_printf(seq, " backtrace:\n");
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100363
364 for (i = 0; i < object->trace_len; i++) {
365 void *ptr = (void *)object->trace[i];
Catalin Marinasbab4a342009-06-26 17:38:26 +0100366 seq_printf(seq, " [<%p>] %pS\n", ptr, ptr);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100367 }
368}
369
370/*
371 * Print the kmemleak_object information. This function is used mainly for
372 * debugging special cases when kmemleak operations. It must be called with
373 * the object->lock held.
374 */
375static void dump_object_info(struct kmemleak_object *object)
376{
377 struct stack_trace trace;
378
379 trace.nr_entries = object->trace_len;
380 trace.entries = object->trace;
381
Joe Perchesae281062009-06-23 14:40:26 +0100382 pr_notice("Object 0x%08lx (size %zu):\n",
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100383 object->tree_node.start, object->size);
384 pr_notice(" comm \"%s\", pid %d, jiffies %lu\n",
385 object->comm, object->pid, object->jiffies);
386 pr_notice(" min_count = %d\n", object->min_count);
387 pr_notice(" count = %d\n", object->count);
Catalin Marinas189d84e2009-08-27 14:29:15 +0100388 pr_notice(" flags = 0x%lx\n", object->flags);
Catalin Marinas04609ccc2009-10-28 13:33:12 +0000389 pr_notice(" checksum = %d\n", object->checksum);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100390 pr_notice(" backtrace:\n");
391 print_stack_trace(&trace, 4);
392}
393
394/*
395 * Look-up a memory block metadata (kmemleak_object) in the priority search
396 * tree based on a pointer value. If alias is 0, only values pointing to the
397 * beginning of the memory block are allowed. The kmemleak_lock must be held
398 * when calling this function.
399 */
400static struct kmemleak_object *lookup_object(unsigned long ptr, int alias)
401{
402 struct prio_tree_node *node;
403 struct prio_tree_iter iter;
404 struct kmemleak_object *object;
405
406 prio_tree_iter_init(&iter, &object_tree_root, ptr, ptr);
407 node = prio_tree_next(&iter);
408 if (node) {
409 object = prio_tree_entry(node, struct kmemleak_object,
410 tree_node);
411 if (!alias && object->pointer != ptr) {
Catalin Marinas5f790202011-09-28 12:17:03 +0100412 kmemleak_warn("Found object by alias at 0x%08lx\n",
413 ptr);
Catalin Marinasa7686a42010-07-19 11:54:16 +0100414 dump_object_info(object);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100415 object = NULL;
416 }
417 } else
418 object = NULL;
419
420 return object;
421}
422
423/*
424 * Increment the object use_count. Return 1 if successful or 0 otherwise. Note
425 * that once an object's use_count reached 0, the RCU freeing was already
426 * registered and the object should no longer be used. This function must be
427 * called under the protection of rcu_read_lock().
428 */
429static int get_object(struct kmemleak_object *object)
430{
431 return atomic_inc_not_zero(&object->use_count);
432}
433
434/*
435 * RCU callback to free a kmemleak_object.
436 */
437static void free_object_rcu(struct rcu_head *rcu)
438{
439 struct hlist_node *elem, *tmp;
440 struct kmemleak_scan_area *area;
441 struct kmemleak_object *object =
442 container_of(rcu, struct kmemleak_object, rcu);
443
444 /*
445 * Once use_count is 0 (guaranteed by put_object), there is no other
446 * code accessing this object, hence no need for locking.
447 */
448 hlist_for_each_entry_safe(area, elem, tmp, &object->area_list, node) {
449 hlist_del(elem);
450 kmem_cache_free(scan_area_cache, area);
451 }
452 kmem_cache_free(object_cache, object);
453}
454
455/*
456 * Decrement the object use_count. Once the count is 0, free the object using
457 * an RCU callback. Since put_object() may be called via the kmemleak_free() ->
458 * delete_object() path, the delayed RCU freeing ensures that there is no
459 * recursive call to the kernel allocator. Lock-less RCU object_list traversal
460 * is also possible.
461 */
462static void put_object(struct kmemleak_object *object)
463{
464 if (!atomic_dec_and_test(&object->use_count))
465 return;
466
467 /* should only get here after delete_object was called */
468 WARN_ON(object->flags & OBJECT_ALLOCATED);
469
470 call_rcu(&object->rcu, free_object_rcu);
471}
472
473/*
474 * Look up an object in the prio search tree and increase its use_count.
475 */
476static struct kmemleak_object *find_and_get_object(unsigned long ptr, int alias)
477{
478 unsigned long flags;
479 struct kmemleak_object *object = NULL;
480
481 rcu_read_lock();
482 read_lock_irqsave(&kmemleak_lock, flags);
483 if (ptr >= min_addr && ptr < max_addr)
484 object = lookup_object(ptr, alias);
485 read_unlock_irqrestore(&kmemleak_lock, flags);
486
487 /* check whether the object is still available */
488 if (object && !get_object(object))
489 object = NULL;
490 rcu_read_unlock();
491
492 return object;
493}
494
495/*
Catalin Marinasfd678962009-08-27 14:29:17 +0100496 * Save stack trace to the given array of MAX_TRACE size.
497 */
498static int __save_stack_trace(unsigned long *trace)
499{
500 struct stack_trace stack_trace;
501
502 stack_trace.max_entries = MAX_TRACE;
503 stack_trace.nr_entries = 0;
504 stack_trace.entries = trace;
505 stack_trace.skip = 2;
506 save_stack_trace(&stack_trace);
507
508 return stack_trace.nr_entries;
509}
510
511/*
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100512 * Create the metadata (struct kmemleak_object) corresponding to an allocated
513 * memory block and add it to the object_list and object_tree_root.
514 */
Catalin Marinasfd678962009-08-27 14:29:17 +0100515static struct kmemleak_object *create_object(unsigned long ptr, size_t size,
516 int min_count, gfp_t gfp)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100517{
518 unsigned long flags;
519 struct kmemleak_object *object;
520 struct prio_tree_node *node;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100521
Catalin Marinas6ae4bd12011-01-27 10:30:26 +0000522 object = kmem_cache_alloc(object_cache, gfp_kmemleak_mask(gfp));
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100523 if (!object) {
Catalin Marinas6ae4bd12011-01-27 10:30:26 +0000524 pr_warning("Cannot allocate a kmemleak_object structure\n");
525 kmemleak_disable();
Catalin Marinasfd678962009-08-27 14:29:17 +0100526 return NULL;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100527 }
528
529 INIT_LIST_HEAD(&object->object_list);
530 INIT_LIST_HEAD(&object->gray_list);
531 INIT_HLIST_HEAD(&object->area_list);
532 spin_lock_init(&object->lock);
533 atomic_set(&object->use_count, 1);
Catalin Marinas04609ccc2009-10-28 13:33:12 +0000534 object->flags = OBJECT_ALLOCATED;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100535 object->pointer = ptr;
536 object->size = size;
537 object->min_count = min_count;
Catalin Marinas04609ccc2009-10-28 13:33:12 +0000538 object->count = 0; /* white color initially */
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100539 object->jiffies = jiffies;
Catalin Marinas04609ccc2009-10-28 13:33:12 +0000540 object->checksum = 0;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100541
542 /* task information */
543 if (in_irq()) {
544 object->pid = 0;
545 strncpy(object->comm, "hardirq", sizeof(object->comm));
546 } else if (in_softirq()) {
547 object->pid = 0;
548 strncpy(object->comm, "softirq", sizeof(object->comm));
549 } else {
550 object->pid = current->pid;
551 /*
552 * There is a small chance of a race with set_task_comm(),
553 * however using get_task_comm() here may cause locking
554 * dependency issues with current->alloc_lock. In the worst
555 * case, the command line is not correct.
556 */
557 strncpy(object->comm, current->comm, sizeof(object->comm));
558 }
559
560 /* kernel backtrace */
Catalin Marinasfd678962009-08-27 14:29:17 +0100561 object->trace_len = __save_stack_trace(object->trace);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100562
563 INIT_PRIO_TREE_NODE(&object->tree_node);
564 object->tree_node.start = ptr;
565 object->tree_node.last = ptr + size - 1;
566
567 write_lock_irqsave(&kmemleak_lock, flags);
Luis R. Rodriguez0580a182009-09-08 17:32:34 +0100568
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100569 min_addr = min(min_addr, ptr);
570 max_addr = max(max_addr, ptr + size);
571 node = prio_tree_insert(&object_tree_root, &object->tree_node);
572 /*
573 * The code calling the kernel does not yet have the pointer to the
574 * memory block to be able to free it. However, we still hold the
575 * kmemleak_lock here in case parts of the kernel started freeing
576 * random memory blocks.
577 */
578 if (node != &object->tree_node) {
Joe Perchesae281062009-06-23 14:40:26 +0100579 kmemleak_stop("Cannot insert 0x%lx into the object search tree "
580 "(already existing)\n", ptr);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100581 object = lookup_object(ptr, 1);
Luis R. Rodriguez0580a182009-09-08 17:32:34 +0100582 spin_lock(&object->lock);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100583 dump_object_info(object);
Luis R. Rodriguez0580a182009-09-08 17:32:34 +0100584 spin_unlock(&object->lock);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100585
586 goto out;
587 }
588 list_add_tail_rcu(&object->object_list, &object_list);
589out:
590 write_unlock_irqrestore(&kmemleak_lock, flags);
Catalin Marinasfd678962009-08-27 14:29:17 +0100591 return object;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100592}
593
594/*
595 * Remove the metadata (struct kmemleak_object) for a memory block from the
596 * object_list and object_tree_root and decrement its use_count.
597 */
Catalin Marinas53238a62009-07-07 10:33:00 +0100598static void __delete_object(struct kmemleak_object *object)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100599{
600 unsigned long flags;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100601
602 write_lock_irqsave(&kmemleak_lock, flags);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100603 prio_tree_remove(&object_tree_root, &object->tree_node);
604 list_del_rcu(&object->object_list);
605 write_unlock_irqrestore(&kmemleak_lock, flags);
606
607 WARN_ON(!(object->flags & OBJECT_ALLOCATED));
Catalin Marinas53238a62009-07-07 10:33:00 +0100608 WARN_ON(atomic_read(&object->use_count) < 2);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100609
610 /*
611 * Locking here also ensures that the corresponding memory block
612 * cannot be freed when it is being scanned.
613 */
614 spin_lock_irqsave(&object->lock, flags);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100615 object->flags &= ~OBJECT_ALLOCATED;
616 spin_unlock_irqrestore(&object->lock, flags);
617 put_object(object);
618}
619
620/*
Catalin Marinas53238a62009-07-07 10:33:00 +0100621 * Look up the metadata (struct kmemleak_object) corresponding to ptr and
622 * delete it.
623 */
624static void delete_object_full(unsigned long ptr)
625{
626 struct kmemleak_object *object;
627
628 object = find_and_get_object(ptr, 0);
629 if (!object) {
630#ifdef DEBUG
631 kmemleak_warn("Freeing unknown object at 0x%08lx\n",
632 ptr);
633#endif
634 return;
635 }
636 __delete_object(object);
637 put_object(object);
638}
639
640/*
641 * Look up the metadata (struct kmemleak_object) corresponding to ptr and
642 * delete it. If the memory block is partially freed, the function may create
643 * additional metadata for the remaining parts of the block.
644 */
645static void delete_object_part(unsigned long ptr, size_t size)
646{
647 struct kmemleak_object *object;
648 unsigned long start, end;
649
650 object = find_and_get_object(ptr, 1);
651 if (!object) {
652#ifdef DEBUG
653 kmemleak_warn("Partially freeing unknown object at 0x%08lx "
654 "(size %zu)\n", ptr, size);
655#endif
656 return;
657 }
658 __delete_object(object);
659
660 /*
661 * Create one or two objects that may result from the memory block
662 * split. Note that partial freeing is only done by free_bootmem() and
663 * this happens before kmemleak_init() is called. The path below is
664 * only executed during early log recording in kmemleak_init(), so
665 * GFP_KERNEL is enough.
666 */
667 start = object->pointer;
668 end = object->pointer + object->size;
669 if (ptr > start)
670 create_object(start, ptr - start, object->min_count,
671 GFP_KERNEL);
672 if (ptr + size < end)
673 create_object(ptr + size, end - ptr - size, object->min_count,
674 GFP_KERNEL);
675
676 put_object(object);
677}
Luis R. Rodrigueza1084c82009-09-04 17:44:52 -0700678
679static void __paint_it(struct kmemleak_object *object, int color)
680{
681 object->min_count = color;
682 if (color == KMEMLEAK_BLACK)
683 object->flags |= OBJECT_NO_SCAN;
684}
685
686static void paint_it(struct kmemleak_object *object, int color)
687{
688 unsigned long flags;
689
690 spin_lock_irqsave(&object->lock, flags);
691 __paint_it(object, color);
692 spin_unlock_irqrestore(&object->lock, flags);
693}
694
695static void paint_ptr(unsigned long ptr, int color)
696{
697 struct kmemleak_object *object;
698
699 object = find_and_get_object(ptr, 0);
700 if (!object) {
701 kmemleak_warn("Trying to color unknown object "
702 "at 0x%08lx as %s\n", ptr,
703 (color == KMEMLEAK_GREY) ? "Grey" :
704 (color == KMEMLEAK_BLACK) ? "Black" : "Unknown");
705 return;
706 }
707 paint_it(object, color);
708 put_object(object);
709}
710
Catalin Marinas53238a62009-07-07 10:33:00 +0100711/*
Holger Hans Peter Freyther145b64b2010-07-22 19:54:13 +0800712 * Mark an object permanently as gray-colored so that it can no longer be
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100713 * reported as a leak. This is used in general to mark a false positive.
714 */
715static void make_gray_object(unsigned long ptr)
716{
Luis R. Rodrigueza1084c82009-09-04 17:44:52 -0700717 paint_ptr(ptr, KMEMLEAK_GREY);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100718}
719
720/*
721 * Mark the object as black-colored so that it is ignored from scans and
722 * reporting.
723 */
724static void make_black_object(unsigned long ptr)
725{
Luis R. Rodrigueza1084c82009-09-04 17:44:52 -0700726 paint_ptr(ptr, KMEMLEAK_BLACK);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100727}
728
729/*
730 * Add a scanning area to the object. If at least one such area is added,
731 * kmemleak will only scan these ranges rather than the whole memory block.
732 */
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000733static void add_scan_area(unsigned long ptr, size_t size, gfp_t gfp)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100734{
735 unsigned long flags;
736 struct kmemleak_object *object;
737 struct kmemleak_scan_area *area;
738
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000739 object = find_and_get_object(ptr, 1);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100740 if (!object) {
Joe Perchesae281062009-06-23 14:40:26 +0100741 kmemleak_warn("Adding scan area to unknown object at 0x%08lx\n",
742 ptr);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100743 return;
744 }
745
Catalin Marinas6ae4bd12011-01-27 10:30:26 +0000746 area = kmem_cache_alloc(scan_area_cache, gfp_kmemleak_mask(gfp));
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100747 if (!area) {
Catalin Marinas6ae4bd12011-01-27 10:30:26 +0000748 pr_warning("Cannot allocate a scan area\n");
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100749 goto out;
750 }
751
752 spin_lock_irqsave(&object->lock, flags);
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000753 if (ptr + size > object->pointer + object->size) {
Joe Perchesae281062009-06-23 14:40:26 +0100754 kmemleak_warn("Scan area larger than object 0x%08lx\n", ptr);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100755 dump_object_info(object);
756 kmem_cache_free(scan_area_cache, area);
757 goto out_unlock;
758 }
759
760 INIT_HLIST_NODE(&area->node);
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000761 area->start = ptr;
762 area->size = size;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100763
764 hlist_add_head(&area->node, &object->area_list);
765out_unlock:
766 spin_unlock_irqrestore(&object->lock, flags);
767out:
768 put_object(object);
769}
770
771/*
772 * Set the OBJECT_NO_SCAN flag for the object corresponding to the give
773 * pointer. Such object will not be scanned by kmemleak but references to it
774 * are searched.
775 */
776static void object_no_scan(unsigned long ptr)
777{
778 unsigned long flags;
779 struct kmemleak_object *object;
780
781 object = find_and_get_object(ptr, 0);
782 if (!object) {
Joe Perchesae281062009-06-23 14:40:26 +0100783 kmemleak_warn("Not scanning unknown object at 0x%08lx\n", ptr);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100784 return;
785 }
786
787 spin_lock_irqsave(&object->lock, flags);
788 object->flags |= OBJECT_NO_SCAN;
789 spin_unlock_irqrestore(&object->lock, flags);
790 put_object(object);
791}
792
793/*
794 * Log an early kmemleak_* call to the early_log buffer. These calls will be
795 * processed later once kmemleak is fully initialized.
796 */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100797static void __init log_early(int op_type, const void *ptr, size_t size,
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000798 int min_count)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100799{
800 unsigned long flags;
801 struct early_log *log;
802
Catalin Marinasb6693002011-09-28 17:22:56 +0100803 if (atomic_read(&kmemleak_error)) {
804 /* kmemleak stopped recording, just count the requests */
805 crt_early_log++;
806 return;
807 }
808
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100809 if (crt_early_log >= ARRAY_SIZE(early_log)) {
Catalin Marinasa9d90582009-06-25 10:16:11 +0100810 kmemleak_disable();
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100811 return;
812 }
813
814 /*
815 * There is no need for locking since the kernel is still in UP mode
816 * at this stage. Disabling the IRQs is enough.
817 */
818 local_irq_save(flags);
819 log = &early_log[crt_early_log];
820 log->op_type = op_type;
821 log->ptr = ptr;
822 log->size = size;
823 log->min_count = min_count;
Catalin Marinas5f790202011-09-28 12:17:03 +0100824 log->trace_len = __save_stack_trace(log->trace);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100825 crt_early_log++;
826 local_irq_restore(flags);
827}
828
829/*
Catalin Marinasfd678962009-08-27 14:29:17 +0100830 * Log an early allocated block and populate the stack trace.
831 */
832static void early_alloc(struct early_log *log)
833{
834 struct kmemleak_object *object;
835 unsigned long flags;
836 int i;
837
838 if (!atomic_read(&kmemleak_enabled) || !log->ptr || IS_ERR(log->ptr))
839 return;
840
841 /*
842 * RCU locking needed to ensure object is not freed via put_object().
843 */
844 rcu_read_lock();
845 object = create_object((unsigned long)log->ptr, log->size,
Tetsuo Handac1bcd6b2009-10-09 10:39:24 +0100846 log->min_count, GFP_ATOMIC);
Catalin Marinas0d5d1aa2009-10-09 10:30:34 +0100847 if (!object)
848 goto out;
Catalin Marinasfd678962009-08-27 14:29:17 +0100849 spin_lock_irqsave(&object->lock, flags);
850 for (i = 0; i < log->trace_len; i++)
851 object->trace[i] = log->trace[i];
852 object->trace_len = log->trace_len;
853 spin_unlock_irqrestore(&object->lock, flags);
Catalin Marinas0d5d1aa2009-10-09 10:30:34 +0100854out:
Catalin Marinasfd678962009-08-27 14:29:17 +0100855 rcu_read_unlock();
856}
857
Catalin Marinasf528f0b2011-09-26 17:12:53 +0100858/*
859 * Log an early allocated block and populate the stack trace.
860 */
861static void early_alloc_percpu(struct early_log *log)
862{
863 unsigned int cpu;
864 const void __percpu *ptr = log->ptr;
865
866 for_each_possible_cpu(cpu) {
867 log->ptr = per_cpu_ptr(ptr, cpu);
868 early_alloc(log);
869 }
870}
871
Catalin Marinasa2b6bf62010-07-19 11:54:17 +0100872/**
873 * kmemleak_alloc - register a newly allocated object
874 * @ptr: pointer to beginning of the object
875 * @size: size of the object
876 * @min_count: minimum number of references to this object. If during memory
877 * scanning a number of references less than @min_count is found,
878 * the object is reported as a memory leak. If @min_count is 0,
879 * the object is never reported as a leak. If @min_count is -1,
880 * the object is ignored (not scanned and not reported as a leak)
881 * @gfp: kmalloc() flags used for kmemleak internal memory allocations
882 *
883 * This function is called from the kernel allocators when a new object
884 * (memory block) is allocated (kmem_cache_alloc, kmalloc, vmalloc etc.).
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100885 */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100886void __ref kmemleak_alloc(const void *ptr, size_t size, int min_count,
887 gfp_t gfp)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100888{
889 pr_debug("%s(0x%p, %zu, %d)\n", __func__, ptr, size, min_count);
890
891 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
892 create_object((unsigned long)ptr, size, min_count, gfp);
893 else if (atomic_read(&kmemleak_early_log))
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000894 log_early(KMEMLEAK_ALLOC, ptr, size, min_count);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100895}
896EXPORT_SYMBOL_GPL(kmemleak_alloc);
897
Catalin Marinasa2b6bf62010-07-19 11:54:17 +0100898/**
Catalin Marinasf528f0b2011-09-26 17:12:53 +0100899 * kmemleak_alloc_percpu - register a newly allocated __percpu object
900 * @ptr: __percpu pointer to beginning of the object
901 * @size: size of the object
902 *
903 * This function is called from the kernel percpu allocator when a new object
904 * (memory block) is allocated (alloc_percpu). It assumes GFP_KERNEL
905 * allocation.
906 */
907void __ref kmemleak_alloc_percpu(const void __percpu *ptr, size_t size)
908{
909 unsigned int cpu;
910
911 pr_debug("%s(0x%p, %zu)\n", __func__, ptr, size);
912
913 /*
914 * Percpu allocations are only scanned and not reported as leaks
915 * (min_count is set to 0).
916 */
917 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
918 for_each_possible_cpu(cpu)
919 create_object((unsigned long)per_cpu_ptr(ptr, cpu),
920 size, 0, GFP_KERNEL);
921 else if (atomic_read(&kmemleak_early_log))
922 log_early(KMEMLEAK_ALLOC_PERCPU, ptr, size, 0);
923}
924EXPORT_SYMBOL_GPL(kmemleak_alloc_percpu);
925
926/**
Catalin Marinasa2b6bf62010-07-19 11:54:17 +0100927 * kmemleak_free - unregister a previously registered object
928 * @ptr: pointer to beginning of the object
929 *
930 * This function is called from the kernel allocators when an object (memory
931 * block) is freed (kmem_cache_free, kfree, vfree etc.).
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100932 */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100933void __ref kmemleak_free(const void *ptr)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100934{
935 pr_debug("%s(0x%p)\n", __func__, ptr);
936
937 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
Catalin Marinas53238a62009-07-07 10:33:00 +0100938 delete_object_full((unsigned long)ptr);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100939 else if (atomic_read(&kmemleak_early_log))
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000940 log_early(KMEMLEAK_FREE, ptr, 0, 0);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100941}
942EXPORT_SYMBOL_GPL(kmemleak_free);
943
Catalin Marinasa2b6bf62010-07-19 11:54:17 +0100944/**
945 * kmemleak_free_part - partially unregister a previously registered object
946 * @ptr: pointer to the beginning or inside the object. This also
947 * represents the start of the range to be freed
948 * @size: size to be unregistered
949 *
950 * This function is called when only a part of a memory block is freed
951 * (usually from the bootmem allocator).
Catalin Marinas53238a62009-07-07 10:33:00 +0100952 */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100953void __ref kmemleak_free_part(const void *ptr, size_t size)
Catalin Marinas53238a62009-07-07 10:33:00 +0100954{
955 pr_debug("%s(0x%p)\n", __func__, ptr);
956
957 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
958 delete_object_part((unsigned long)ptr, size);
959 else if (atomic_read(&kmemleak_early_log))
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000960 log_early(KMEMLEAK_FREE_PART, ptr, size, 0);
Catalin Marinas53238a62009-07-07 10:33:00 +0100961}
962EXPORT_SYMBOL_GPL(kmemleak_free_part);
963
Catalin Marinasa2b6bf62010-07-19 11:54:17 +0100964/**
Catalin Marinasf528f0b2011-09-26 17:12:53 +0100965 * kmemleak_free_percpu - unregister a previously registered __percpu object
966 * @ptr: __percpu pointer to beginning of the object
967 *
968 * This function is called from the kernel percpu allocator when an object
969 * (memory block) is freed (free_percpu).
970 */
971void __ref kmemleak_free_percpu(const void __percpu *ptr)
972{
973 unsigned int cpu;
974
975 pr_debug("%s(0x%p)\n", __func__, ptr);
976
977 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
978 for_each_possible_cpu(cpu)
979 delete_object_full((unsigned long)per_cpu_ptr(ptr,
980 cpu));
981 else if (atomic_read(&kmemleak_early_log))
982 log_early(KMEMLEAK_FREE_PERCPU, ptr, 0, 0);
983}
984EXPORT_SYMBOL_GPL(kmemleak_free_percpu);
985
986/**
Catalin Marinasa2b6bf62010-07-19 11:54:17 +0100987 * kmemleak_not_leak - mark an allocated object as false positive
988 * @ptr: pointer to beginning of the object
989 *
990 * Calling this function on an object will cause the memory block to no longer
991 * be reported as leak and always be scanned.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100992 */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100993void __ref kmemleak_not_leak(const void *ptr)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100994{
995 pr_debug("%s(0x%p)\n", __func__, ptr);
996
997 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
998 make_gray_object((unsigned long)ptr);
999 else if (atomic_read(&kmemleak_early_log))
Catalin Marinasc017b4b2009-10-28 13:33:09 +00001000 log_early(KMEMLEAK_NOT_LEAK, ptr, 0, 0);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001001}
1002EXPORT_SYMBOL(kmemleak_not_leak);
1003
Catalin Marinasa2b6bf62010-07-19 11:54:17 +01001004/**
1005 * kmemleak_ignore - ignore an allocated object
1006 * @ptr: pointer to beginning of the object
1007 *
1008 * Calling this function on an object will cause the memory block to be
1009 * ignored (not scanned and not reported as a leak). This is usually done when
1010 * it is known that the corresponding block is not a leak and does not contain
1011 * any references to other allocated memory blocks.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001012 */
Catalin Marinasa6186d82009-08-27 14:29:16 +01001013void __ref kmemleak_ignore(const void *ptr)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001014{
1015 pr_debug("%s(0x%p)\n", __func__, ptr);
1016
1017 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
1018 make_black_object((unsigned long)ptr);
1019 else if (atomic_read(&kmemleak_early_log))
Catalin Marinasc017b4b2009-10-28 13:33:09 +00001020 log_early(KMEMLEAK_IGNORE, ptr, 0, 0);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001021}
1022EXPORT_SYMBOL(kmemleak_ignore);
1023
Catalin Marinasa2b6bf62010-07-19 11:54:17 +01001024/**
1025 * kmemleak_scan_area - limit the range to be scanned in an allocated object
1026 * @ptr: pointer to beginning or inside the object. This also
1027 * represents the start of the scan area
1028 * @size: size of the scan area
1029 * @gfp: kmalloc() flags used for kmemleak internal memory allocations
1030 *
1031 * This function is used when it is known that only certain parts of an object
1032 * contain references to other objects. Kmemleak will only scan these areas
1033 * reducing the number false negatives.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001034 */
Catalin Marinasc017b4b2009-10-28 13:33:09 +00001035void __ref kmemleak_scan_area(const void *ptr, size_t size, gfp_t gfp)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001036{
1037 pr_debug("%s(0x%p)\n", __func__, ptr);
1038
1039 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
Catalin Marinasc017b4b2009-10-28 13:33:09 +00001040 add_scan_area((unsigned long)ptr, size, gfp);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001041 else if (atomic_read(&kmemleak_early_log))
Catalin Marinasc017b4b2009-10-28 13:33:09 +00001042 log_early(KMEMLEAK_SCAN_AREA, ptr, size, 0);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001043}
1044EXPORT_SYMBOL(kmemleak_scan_area);
1045
Catalin Marinasa2b6bf62010-07-19 11:54:17 +01001046/**
1047 * kmemleak_no_scan - do not scan an allocated object
1048 * @ptr: pointer to beginning of the object
1049 *
1050 * This function notifies kmemleak not to scan the given memory block. Useful
1051 * in situations where it is known that the given object does not contain any
1052 * references to other objects. Kmemleak will not scan such objects reducing
1053 * the number of false negatives.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001054 */
Catalin Marinasa6186d82009-08-27 14:29:16 +01001055void __ref kmemleak_no_scan(const void *ptr)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001056{
1057 pr_debug("%s(0x%p)\n", __func__, ptr);
1058
1059 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
1060 object_no_scan((unsigned long)ptr);
1061 else if (atomic_read(&kmemleak_early_log))
Catalin Marinasc017b4b2009-10-28 13:33:09 +00001062 log_early(KMEMLEAK_NO_SCAN, ptr, 0, 0);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001063}
1064EXPORT_SYMBOL(kmemleak_no_scan);
1065
1066/*
Catalin Marinas04609ccc2009-10-28 13:33:12 +00001067 * Update an object's checksum and return true if it was modified.
1068 */
1069static bool update_checksum(struct kmemleak_object *object)
1070{
1071 u32 old_csum = object->checksum;
1072
1073 if (!kmemcheck_is_obj_initialized(object->pointer, object->size))
1074 return false;
1075
1076 object->checksum = crc32(0, (void *)object->pointer, object->size);
1077 return object->checksum != old_csum;
1078}
1079
1080/*
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001081 * Memory scanning is a long process and it needs to be interruptable. This
Lucas De Marchi25985ed2011-03-30 22:57:33 -03001082 * function checks whether such interrupt condition occurred.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001083 */
1084static int scan_should_stop(void)
1085{
1086 if (!atomic_read(&kmemleak_enabled))
1087 return 1;
1088
1089 /*
1090 * This function may be called from either process or kthread context,
1091 * hence the need to check for both stop conditions.
1092 */
1093 if (current->mm)
1094 return signal_pending(current);
1095 else
1096 return kthread_should_stop();
1097
1098 return 0;
1099}
1100
1101/*
1102 * Scan a memory block (exclusive range) for valid pointers and add those
1103 * found to the gray list.
1104 */
1105static void scan_block(void *_start, void *_end,
Catalin Marinas4b8a9672009-07-07 10:32:56 +01001106 struct kmemleak_object *scanned, int allow_resched)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001107{
1108 unsigned long *ptr;
1109 unsigned long *start = PTR_ALIGN(_start, BYTES_PER_POINTER);
1110 unsigned long *end = _end - (BYTES_PER_POINTER - 1);
1111
1112 for (ptr = start; ptr < end; ptr++) {
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001113 struct kmemleak_object *object;
Pekka Enberg8e019362009-08-27 14:50:00 +01001114 unsigned long flags;
1115 unsigned long pointer;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001116
Catalin Marinas4b8a9672009-07-07 10:32:56 +01001117 if (allow_resched)
1118 cond_resched();
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001119 if (scan_should_stop())
1120 break;
1121
Pekka Enberg8e019362009-08-27 14:50:00 +01001122 /* don't scan uninitialized memory */
1123 if (!kmemcheck_is_obj_initialized((unsigned long)ptr,
1124 BYTES_PER_POINTER))
1125 continue;
1126
1127 pointer = *ptr;
1128
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001129 object = find_and_get_object(pointer, 1);
1130 if (!object)
1131 continue;
1132 if (object == scanned) {
1133 /* self referenced, ignore */
1134 put_object(object);
1135 continue;
1136 }
1137
1138 /*
1139 * Avoid the lockdep recursive warning on object->lock being
1140 * previously acquired in scan_object(). These locks are
1141 * enclosed by scan_mutex.
1142 */
1143 spin_lock_irqsave_nested(&object->lock, flags,
1144 SINGLE_DEPTH_NESTING);
1145 if (!color_white(object)) {
1146 /* non-orphan, ignored or new */
1147 spin_unlock_irqrestore(&object->lock, flags);
1148 put_object(object);
1149 continue;
1150 }
1151
1152 /*
1153 * Increase the object's reference count (number of pointers
1154 * to the memory block). If this count reaches the required
1155 * minimum, the object's color will become gray and it will be
1156 * added to the gray_list.
1157 */
1158 object->count++;
Catalin Marinas0587da42009-10-28 13:33:11 +00001159 if (color_gray(object)) {
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001160 list_add_tail(&object->gray_list, &gray_list);
Catalin Marinas0587da42009-10-28 13:33:11 +00001161 spin_unlock_irqrestore(&object->lock, flags);
1162 continue;
1163 }
1164
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001165 spin_unlock_irqrestore(&object->lock, flags);
Catalin Marinas0587da42009-10-28 13:33:11 +00001166 put_object(object);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001167 }
1168}
1169
1170/*
1171 * Scan a memory block corresponding to a kmemleak_object. A condition is
1172 * that object->use_count >= 1.
1173 */
1174static void scan_object(struct kmemleak_object *object)
1175{
1176 struct kmemleak_scan_area *area;
1177 struct hlist_node *elem;
1178 unsigned long flags;
1179
1180 /*
Uwe Kleine-König21ae2952009-10-07 15:21:09 +02001181 * Once the object->lock is acquired, the corresponding memory block
1182 * cannot be freed (the same lock is acquired in delete_object).
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001183 */
1184 spin_lock_irqsave(&object->lock, flags);
1185 if (object->flags & OBJECT_NO_SCAN)
1186 goto out;
1187 if (!(object->flags & OBJECT_ALLOCATED))
1188 /* already freed object */
1189 goto out;
Catalin Marinasaf986032009-08-27 14:29:12 +01001190 if (hlist_empty(&object->area_list)) {
1191 void *start = (void *)object->pointer;
1192 void *end = (void *)(object->pointer + object->size);
1193
1194 while (start < end && (object->flags & OBJECT_ALLOCATED) &&
1195 !(object->flags & OBJECT_NO_SCAN)) {
1196 scan_block(start, min(start + MAX_SCAN_SIZE, end),
1197 object, 0);
1198 start += MAX_SCAN_SIZE;
1199
1200 spin_unlock_irqrestore(&object->lock, flags);
1201 cond_resched();
1202 spin_lock_irqsave(&object->lock, flags);
1203 }
1204 } else
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001205 hlist_for_each_entry(area, elem, &object->area_list, node)
Catalin Marinasc017b4b2009-10-28 13:33:09 +00001206 scan_block((void *)area->start,
1207 (void *)(area->start + area->size),
1208 object, 0);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001209out:
1210 spin_unlock_irqrestore(&object->lock, flags);
1211}
1212
1213/*
Catalin Marinas04609ccc2009-10-28 13:33:12 +00001214 * Scan the objects already referenced (gray objects). More objects will be
1215 * referenced and, if there are no memory leaks, all the objects are scanned.
1216 */
1217static void scan_gray_list(void)
1218{
1219 struct kmemleak_object *object, *tmp;
1220
1221 /*
1222 * The list traversal is safe for both tail additions and removals
1223 * from inside the loop. The kmemleak objects cannot be freed from
1224 * outside the loop because their use_count was incremented.
1225 */
1226 object = list_entry(gray_list.next, typeof(*object), gray_list);
1227 while (&object->gray_list != &gray_list) {
1228 cond_resched();
1229
1230 /* may add new objects to the list */
1231 if (!scan_should_stop())
1232 scan_object(object);
1233
1234 tmp = list_entry(object->gray_list.next, typeof(*object),
1235 gray_list);
1236
1237 /* remove the object from the list and release it */
1238 list_del(&object->gray_list);
1239 put_object(object);
1240
1241 object = tmp;
1242 }
1243 WARN_ON(!list_empty(&gray_list));
1244}
1245
1246/*
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001247 * Scan data sections and all the referenced memory blocks allocated via the
1248 * kernel's standard allocators. This function must be called with the
1249 * scan_mutex held.
1250 */
1251static void kmemleak_scan(void)
1252{
1253 unsigned long flags;
Catalin Marinas04609ccc2009-10-28 13:33:12 +00001254 struct kmemleak_object *object;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001255 int i;
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001256 int new_leaks = 0;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001257
Catalin Marinasacf49682009-06-26 17:38:29 +01001258 jiffies_last_scan = jiffies;
1259
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001260 /* prepare the kmemleak_object's */
1261 rcu_read_lock();
1262 list_for_each_entry_rcu(object, &object_list, object_list) {
1263 spin_lock_irqsave(&object->lock, flags);
1264#ifdef DEBUG
1265 /*
1266 * With a few exceptions there should be a maximum of
1267 * 1 reference to any object at this point.
1268 */
1269 if (atomic_read(&object->use_count) > 1) {
Joe Perchesae281062009-06-23 14:40:26 +01001270 pr_debug("object->use_count = %d\n",
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001271 atomic_read(&object->use_count));
1272 dump_object_info(object);
1273 }
1274#endif
1275 /* reset the reference count (whiten the object) */
1276 object->count = 0;
1277 if (color_gray(object) && get_object(object))
1278 list_add_tail(&object->gray_list, &gray_list);
1279
1280 spin_unlock_irqrestore(&object->lock, flags);
1281 }
1282 rcu_read_unlock();
1283
1284 /* data/bss scanning */
Catalin Marinas4b8a9672009-07-07 10:32:56 +01001285 scan_block(_sdata, _edata, NULL, 1);
1286 scan_block(__bss_start, __bss_stop, NULL, 1);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001287
1288#ifdef CONFIG_SMP
1289 /* per-cpu sections scanning */
1290 for_each_possible_cpu(i)
1291 scan_block(__per_cpu_start + per_cpu_offset(i),
Catalin Marinas4b8a9672009-07-07 10:32:56 +01001292 __per_cpu_end + per_cpu_offset(i), NULL, 1);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001293#endif
1294
1295 /*
Laura Abbott029aeff2011-11-15 23:49:09 +00001296 * Struct page scanning for each node.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001297 */
Laura Abbott029aeff2011-11-15 23:49:09 +00001298 lock_memory_hotplug();
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001299 for_each_online_node(i) {
1300 pg_data_t *pgdat = NODE_DATA(i);
1301 unsigned long start_pfn = pgdat->node_start_pfn;
1302 unsigned long end_pfn = start_pfn + pgdat->node_spanned_pages;
1303 unsigned long pfn;
1304
1305 for (pfn = start_pfn; pfn < end_pfn; pfn++) {
1306 struct page *page;
1307
1308 if (!pfn_valid(pfn))
1309 continue;
1310 page = pfn_to_page(pfn);
1311 /* only scan if page is in use */
1312 if (page_count(page) == 0)
1313 continue;
Catalin Marinas4b8a9672009-07-07 10:32:56 +01001314 scan_block(page, page + 1, NULL, 1);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001315 }
1316 }
Laura Abbott029aeff2011-11-15 23:49:09 +00001317 unlock_memory_hotplug();
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001318
1319 /*
Catalin Marinas43ed5d62009-09-01 11:12:44 +01001320 * Scanning the task stacks (may introduce false negatives).
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001321 */
1322 if (kmemleak_stack_scan) {
Catalin Marinas43ed5d62009-09-01 11:12:44 +01001323 struct task_struct *p, *g;
1324
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001325 read_lock(&tasklist_lock);
Catalin Marinas43ed5d62009-09-01 11:12:44 +01001326 do_each_thread(g, p) {
1327 scan_block(task_stack_page(p), task_stack_page(p) +
1328 THREAD_SIZE, NULL, 0);
1329 } while_each_thread(g, p);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001330 read_unlock(&tasklist_lock);
1331 }
1332
1333 /*
1334 * Scan the objects already referenced from the sections scanned
Catalin Marinas04609ccc2009-10-28 13:33:12 +00001335 * above.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001336 */
Catalin Marinas04609ccc2009-10-28 13:33:12 +00001337 scan_gray_list();
Catalin Marinas25873622009-07-07 10:32:58 +01001338
1339 /*
Catalin Marinas04609ccc2009-10-28 13:33:12 +00001340 * Check for new or unreferenced objects modified since the previous
1341 * scan and color them gray until the next scan.
Catalin Marinas25873622009-07-07 10:32:58 +01001342 */
1343 rcu_read_lock();
1344 list_for_each_entry_rcu(object, &object_list, object_list) {
1345 spin_lock_irqsave(&object->lock, flags);
Catalin Marinas04609ccc2009-10-28 13:33:12 +00001346 if (color_white(object) && (object->flags & OBJECT_ALLOCATED)
1347 && update_checksum(object) && get_object(object)) {
1348 /* color it gray temporarily */
1349 object->count = object->min_count;
Catalin Marinas25873622009-07-07 10:32:58 +01001350 list_add_tail(&object->gray_list, &gray_list);
1351 }
1352 spin_unlock_irqrestore(&object->lock, flags);
1353 }
1354 rcu_read_unlock();
1355
Catalin Marinas04609ccc2009-10-28 13:33:12 +00001356 /*
1357 * Re-scan the gray list for modified unreferenced objects.
1358 */
1359 scan_gray_list();
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001360
1361 /*
Catalin Marinas04609ccc2009-10-28 13:33:12 +00001362 * If scanning was stopped do not report any new unreferenced objects.
Catalin Marinas17bb9e02009-06-29 17:13:56 +01001363 */
Catalin Marinas04609ccc2009-10-28 13:33:12 +00001364 if (scan_should_stop())
Catalin Marinas17bb9e02009-06-29 17:13:56 +01001365 return;
1366
1367 /*
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001368 * Scanning result reporting.
1369 */
1370 rcu_read_lock();
1371 list_for_each_entry_rcu(object, &object_list, object_list) {
1372 spin_lock_irqsave(&object->lock, flags);
1373 if (unreferenced_object(object) &&
1374 !(object->flags & OBJECT_REPORTED)) {
1375 object->flags |= OBJECT_REPORTED;
1376 new_leaks++;
1377 }
1378 spin_unlock_irqrestore(&object->lock, flags);
1379 }
1380 rcu_read_unlock();
1381
1382 if (new_leaks)
1383 pr_info("%d new suspected memory leaks (see "
1384 "/sys/kernel/debug/kmemleak)\n", new_leaks);
1385
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001386}
1387
1388/*
1389 * Thread function performing automatic memory scanning. Unreferenced objects
1390 * at the end of a memory scan are reported but only the first time.
1391 */
1392static int kmemleak_scan_thread(void *arg)
1393{
1394 static int first_run = 1;
1395
Joe Perchesae281062009-06-23 14:40:26 +01001396 pr_info("Automatic memory scanning thread started\n");
Catalin Marinasbf2a76b2009-07-07 10:32:55 +01001397 set_user_nice(current, 10);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001398
1399 /*
1400 * Wait before the first scan to allow the system to fully initialize.
1401 */
1402 if (first_run) {
1403 first_run = 0;
1404 ssleep(SECS_FIRST_SCAN);
1405 }
1406
1407 while (!kthread_should_stop()) {
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001408 signed long timeout = jiffies_scan_wait;
1409
1410 mutex_lock(&scan_mutex);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001411 kmemleak_scan();
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001412 mutex_unlock(&scan_mutex);
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001413
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001414 /* wait before the next scan */
1415 while (timeout && !kthread_should_stop())
1416 timeout = schedule_timeout_interruptible(timeout);
1417 }
1418
Joe Perchesae281062009-06-23 14:40:26 +01001419 pr_info("Automatic memory scanning thread ended\n");
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001420
1421 return 0;
1422}
1423
1424/*
1425 * Start the automatic memory scanning thread. This function must be called
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001426 * with the scan_mutex held.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001427 */
Luis R. Rodriguez7eb0d5e2009-09-08 17:31:45 +01001428static void start_scan_thread(void)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001429{
1430 if (scan_thread)
1431 return;
1432 scan_thread = kthread_run(kmemleak_scan_thread, NULL, "kmemleak");
1433 if (IS_ERR(scan_thread)) {
Joe Perchesae281062009-06-23 14:40:26 +01001434 pr_warning("Failed to create the scan thread\n");
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001435 scan_thread = NULL;
1436 }
1437}
1438
1439/*
1440 * Stop the automatic memory scanning thread. This function must be called
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001441 * with the scan_mutex held.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001442 */
Luis R. Rodriguez7eb0d5e2009-09-08 17:31:45 +01001443static void stop_scan_thread(void)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001444{
1445 if (scan_thread) {
1446 kthread_stop(scan_thread);
1447 scan_thread = NULL;
1448 }
1449}
1450
1451/*
1452 * Iterate over the object_list and return the first valid object at or after
1453 * the required position with its use_count incremented. The function triggers
1454 * a memory scanning when the pos argument points to the first position.
1455 */
1456static void *kmemleak_seq_start(struct seq_file *seq, loff_t *pos)
1457{
1458 struct kmemleak_object *object;
1459 loff_t n = *pos;
Catalin Marinasb87324d2009-07-07 10:32:58 +01001460 int err;
1461
1462 err = mutex_lock_interruptible(&scan_mutex);
1463 if (err < 0)
1464 return ERR_PTR(err);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001465
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001466 rcu_read_lock();
1467 list_for_each_entry_rcu(object, &object_list, object_list) {
1468 if (n-- > 0)
1469 continue;
1470 if (get_object(object))
1471 goto out;
1472 }
1473 object = NULL;
1474out:
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001475 return object;
1476}
1477
1478/*
1479 * Return the next object in the object_list. The function decrements the
1480 * use_count of the previous object and increases that of the next one.
1481 */
1482static void *kmemleak_seq_next(struct seq_file *seq, void *v, loff_t *pos)
1483{
1484 struct kmemleak_object *prev_obj = v;
1485 struct kmemleak_object *next_obj = NULL;
1486 struct list_head *n = &prev_obj->object_list;
1487
1488 ++(*pos);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001489
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001490 list_for_each_continue_rcu(n, &object_list) {
Catalin Marinas52c3ce42011-04-27 16:44:26 +01001491 struct kmemleak_object *obj =
1492 list_entry(n, struct kmemleak_object, object_list);
1493 if (get_object(obj)) {
1494 next_obj = obj;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001495 break;
Catalin Marinas52c3ce42011-04-27 16:44:26 +01001496 }
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001497 }
Catalin Marinas288c8572009-07-07 10:32:57 +01001498
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001499 put_object(prev_obj);
1500 return next_obj;
1501}
1502
1503/*
1504 * Decrement the use_count of the last object required, if any.
1505 */
1506static void kmemleak_seq_stop(struct seq_file *seq, void *v)
1507{
Catalin Marinasb87324d2009-07-07 10:32:58 +01001508 if (!IS_ERR(v)) {
1509 /*
1510 * kmemleak_seq_start may return ERR_PTR if the scan_mutex
1511 * waiting was interrupted, so only release it if !IS_ERR.
1512 */
Catalin Marinasf5886c72009-07-29 16:26:57 +01001513 rcu_read_unlock();
Catalin Marinasb87324d2009-07-07 10:32:58 +01001514 mutex_unlock(&scan_mutex);
1515 if (v)
1516 put_object(v);
1517 }
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001518}
1519
1520/*
1521 * Print the information for an unreferenced object to the seq file.
1522 */
1523static int kmemleak_seq_show(struct seq_file *seq, void *v)
1524{
1525 struct kmemleak_object *object = v;
1526 unsigned long flags;
1527
1528 spin_lock_irqsave(&object->lock, flags);
Catalin Marinas288c8572009-07-07 10:32:57 +01001529 if ((object->flags & OBJECT_REPORTED) && unreferenced_object(object))
Catalin Marinas17bb9e02009-06-29 17:13:56 +01001530 print_unreferenced(seq, object);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001531 spin_unlock_irqrestore(&object->lock, flags);
1532 return 0;
1533}
1534
1535static const struct seq_operations kmemleak_seq_ops = {
1536 .start = kmemleak_seq_start,
1537 .next = kmemleak_seq_next,
1538 .stop = kmemleak_seq_stop,
1539 .show = kmemleak_seq_show,
1540};
1541
1542static int kmemleak_open(struct inode *inode, struct file *file)
1543{
Catalin Marinasb87324d2009-07-07 10:32:58 +01001544 return seq_open(file, &kmemleak_seq_ops);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001545}
1546
1547static int kmemleak_release(struct inode *inode, struct file *file)
1548{
Catalin Marinasb87324d2009-07-07 10:32:58 +01001549 return seq_release(inode, file);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001550}
1551
Catalin Marinas189d84e2009-08-27 14:29:15 +01001552static int dump_str_object_info(const char *str)
1553{
1554 unsigned long flags;
1555 struct kmemleak_object *object;
1556 unsigned long addr;
1557
1558 addr= simple_strtoul(str, NULL, 0);
1559 object = find_and_get_object(addr, 0);
1560 if (!object) {
1561 pr_info("Unknown object at 0x%08lx\n", addr);
1562 return -EINVAL;
1563 }
1564
1565 spin_lock_irqsave(&object->lock, flags);
1566 dump_object_info(object);
1567 spin_unlock_irqrestore(&object->lock, flags);
1568
1569 put_object(object);
1570 return 0;
1571}
1572
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001573/*
Luis R. Rodriguez30b37102009-09-04 17:44:51 -07001574 * We use grey instead of black to ensure we can do future scans on the same
1575 * objects. If we did not do future scans these black objects could
1576 * potentially contain references to newly allocated objects in the future and
1577 * we'd end up with false positives.
1578 */
1579static void kmemleak_clear(void)
1580{
1581 struct kmemleak_object *object;
1582 unsigned long flags;
1583
1584 rcu_read_lock();
1585 list_for_each_entry_rcu(object, &object_list, object_list) {
1586 spin_lock_irqsave(&object->lock, flags);
1587 if ((object->flags & OBJECT_REPORTED) &&
1588 unreferenced_object(object))
Luis R. Rodrigueza1084c82009-09-04 17:44:52 -07001589 __paint_it(object, KMEMLEAK_GREY);
Luis R. Rodriguez30b37102009-09-04 17:44:51 -07001590 spin_unlock_irqrestore(&object->lock, flags);
1591 }
1592 rcu_read_unlock();
1593}
1594
1595/*
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001596 * File write operation to configure kmemleak at run-time. The following
1597 * commands can be written to the /sys/kernel/debug/kmemleak file:
1598 * off - disable kmemleak (irreversible)
1599 * stack=on - enable the task stacks scanning
1600 * stack=off - disable the tasks stacks scanning
1601 * scan=on - start the automatic memory scanning thread
1602 * scan=off - stop the automatic memory scanning thread
1603 * scan=... - set the automatic memory scanning period in seconds (0 to
1604 * disable it)
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001605 * scan - trigger a memory scan
Luis R. Rodriguez30b37102009-09-04 17:44:51 -07001606 * clear - mark all current reported unreferenced kmemleak objects as
1607 * grey to ignore printing them
Catalin Marinas189d84e2009-08-27 14:29:15 +01001608 * dump=... - dump information about the object found at the given address
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001609 */
1610static ssize_t kmemleak_write(struct file *file, const char __user *user_buf,
1611 size_t size, loff_t *ppos)
1612{
1613 char buf[64];
1614 int buf_size;
Catalin Marinasb87324d2009-07-07 10:32:58 +01001615 int ret;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001616
Catalin Marinas74341702011-09-29 11:50:07 +01001617 if (!atomic_read(&kmemleak_enabled))
1618 return -EBUSY;
1619
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001620 buf_size = min(size, (sizeof(buf) - 1));
1621 if (strncpy_from_user(buf, user_buf, buf_size) < 0)
1622 return -EFAULT;
1623 buf[buf_size] = 0;
1624
Catalin Marinasb87324d2009-07-07 10:32:58 +01001625 ret = mutex_lock_interruptible(&scan_mutex);
1626 if (ret < 0)
1627 return ret;
1628
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001629 if (strncmp(buf, "off", 3) == 0)
1630 kmemleak_disable();
1631 else if (strncmp(buf, "stack=on", 8) == 0)
1632 kmemleak_stack_scan = 1;
1633 else if (strncmp(buf, "stack=off", 9) == 0)
1634 kmemleak_stack_scan = 0;
1635 else if (strncmp(buf, "scan=on", 7) == 0)
1636 start_scan_thread();
1637 else if (strncmp(buf, "scan=off", 8) == 0)
1638 stop_scan_thread();
1639 else if (strncmp(buf, "scan=", 5) == 0) {
1640 unsigned long secs;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001641
Catalin Marinasb87324d2009-07-07 10:32:58 +01001642 ret = strict_strtoul(buf + 5, 0, &secs);
1643 if (ret < 0)
1644 goto out;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001645 stop_scan_thread();
1646 if (secs) {
1647 jiffies_scan_wait = msecs_to_jiffies(secs * 1000);
1648 start_scan_thread();
1649 }
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001650 } else if (strncmp(buf, "scan", 4) == 0)
1651 kmemleak_scan();
Luis R. Rodriguez30b37102009-09-04 17:44:51 -07001652 else if (strncmp(buf, "clear", 5) == 0)
1653 kmemleak_clear();
Catalin Marinas189d84e2009-08-27 14:29:15 +01001654 else if (strncmp(buf, "dump=", 5) == 0)
1655 ret = dump_str_object_info(buf + 5);
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001656 else
Catalin Marinasb87324d2009-07-07 10:32:58 +01001657 ret = -EINVAL;
1658
1659out:
1660 mutex_unlock(&scan_mutex);
1661 if (ret < 0)
1662 return ret;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001663
1664 /* ignore the rest of the buffer, only one command at a time */
1665 *ppos += size;
1666 return size;
1667}
1668
1669static const struct file_operations kmemleak_fops = {
1670 .owner = THIS_MODULE,
1671 .open = kmemleak_open,
1672 .read = seq_read,
1673 .write = kmemleak_write,
1674 .llseek = seq_lseek,
1675 .release = kmemleak_release,
1676};
1677
1678/*
Catalin Marinas74341702011-09-29 11:50:07 +01001679 * Stop the memory scanning thread and free the kmemleak internal objects if
1680 * no previous scan thread (otherwise, kmemleak may still have some useful
1681 * information on memory leaks).
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001682 */
Catalin Marinas179a8102009-09-07 10:14:42 +01001683static void kmemleak_do_cleanup(struct work_struct *work)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001684{
1685 struct kmemleak_object *object;
Catalin Marinas74341702011-09-29 11:50:07 +01001686 bool cleanup = scan_thread == NULL;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001687
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001688 mutex_lock(&scan_mutex);
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001689 stop_scan_thread();
1690
Catalin Marinas74341702011-09-29 11:50:07 +01001691 if (cleanup) {
1692 rcu_read_lock();
1693 list_for_each_entry_rcu(object, &object_list, object_list)
1694 delete_object_full(object->pointer);
1695 rcu_read_unlock();
1696 }
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001697 mutex_unlock(&scan_mutex);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001698}
1699
Catalin Marinas179a8102009-09-07 10:14:42 +01001700static DECLARE_WORK(cleanup_work, kmemleak_do_cleanup);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001701
1702/*
1703 * Disable kmemleak. No memory allocation/freeing will be traced once this
1704 * function is called. Disabling kmemleak is an irreversible operation.
1705 */
1706static void kmemleak_disable(void)
1707{
1708 /* atomically check whether it was already invoked */
1709 if (atomic_cmpxchg(&kmemleak_error, 0, 1))
1710 return;
1711
1712 /* stop any memory operation tracing */
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001713 atomic_set(&kmemleak_enabled, 0);
1714
1715 /* check whether it is too early for a kernel thread */
1716 if (atomic_read(&kmemleak_initialized))
Catalin Marinas179a8102009-09-07 10:14:42 +01001717 schedule_work(&cleanup_work);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001718
1719 pr_info("Kernel memory leak detector disabled\n");
1720}
1721
1722/*
1723 * Allow boot-time kmemleak disabling (enabled by default).
1724 */
1725static int kmemleak_boot_config(char *str)
1726{
1727 if (!str)
1728 return -EINVAL;
1729 if (strcmp(str, "off") == 0)
1730 kmemleak_disable();
Jason Baronab0155a2010-07-19 11:54:17 +01001731 else if (strcmp(str, "on") == 0)
1732 kmemleak_skip_disable = 1;
1733 else
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001734 return -EINVAL;
1735 return 0;
1736}
1737early_param("kmemleak", kmemleak_boot_config);
1738
Catalin Marinas5f790202011-09-28 12:17:03 +01001739static void __init print_log_trace(struct early_log *log)
1740{
1741 struct stack_trace trace;
1742
1743 trace.nr_entries = log->trace_len;
1744 trace.entries = log->trace;
1745
1746 pr_notice("Early log backtrace:\n");
1747 print_stack_trace(&trace, 2);
1748}
1749
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001750/*
Catalin Marinas20301172009-06-17 18:29:04 +01001751 * Kmemleak initialization.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001752 */
1753void __init kmemleak_init(void)
1754{
1755 int i;
1756 unsigned long flags;
1757
Jason Baronab0155a2010-07-19 11:54:17 +01001758#ifdef CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF
1759 if (!kmemleak_skip_disable) {
1760 kmemleak_disable();
1761 return;
1762 }
1763#endif
1764
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001765 jiffies_min_age = msecs_to_jiffies(MSECS_MIN_AGE);
1766 jiffies_scan_wait = msecs_to_jiffies(SECS_SCAN_WAIT * 1000);
1767
1768 object_cache = KMEM_CACHE(kmemleak_object, SLAB_NOLEAKTRACE);
1769 scan_area_cache = KMEM_CACHE(kmemleak_scan_area, SLAB_NOLEAKTRACE);
1770 INIT_PRIO_TREE_ROOT(&object_tree_root);
1771
Catalin Marinasb6693002011-09-28 17:22:56 +01001772 if (crt_early_log >= ARRAY_SIZE(early_log))
1773 pr_warning("Early log buffer exceeded (%d), please increase "
1774 "DEBUG_KMEMLEAK_EARLY_LOG_SIZE\n", crt_early_log);
1775
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001776 /* the kernel is still in UP mode, so disabling the IRQs is enough */
1777 local_irq_save(flags);
Catalin Marinasb6693002011-09-28 17:22:56 +01001778 atomic_set(&kmemleak_early_log, 0);
1779 if (atomic_read(&kmemleak_error)) {
1780 local_irq_restore(flags);
1781 return;
1782 } else
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001783 atomic_set(&kmemleak_enabled, 1);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001784 local_irq_restore(flags);
1785
1786 /*
1787 * This is the point where tracking allocations is safe. Automatic
1788 * scanning is started during the late initcall. Add the early logged
1789 * callbacks to the kmemleak infrastructure.
1790 */
1791 for (i = 0; i < crt_early_log; i++) {
1792 struct early_log *log = &early_log[i];
1793
1794 switch (log->op_type) {
1795 case KMEMLEAK_ALLOC:
Catalin Marinasfd678962009-08-27 14:29:17 +01001796 early_alloc(log);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001797 break;
Catalin Marinasf528f0b2011-09-26 17:12:53 +01001798 case KMEMLEAK_ALLOC_PERCPU:
1799 early_alloc_percpu(log);
1800 break;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001801 case KMEMLEAK_FREE:
1802 kmemleak_free(log->ptr);
1803 break;
Catalin Marinas53238a62009-07-07 10:33:00 +01001804 case KMEMLEAK_FREE_PART:
1805 kmemleak_free_part(log->ptr, log->size);
1806 break;
Catalin Marinasf528f0b2011-09-26 17:12:53 +01001807 case KMEMLEAK_FREE_PERCPU:
1808 kmemleak_free_percpu(log->ptr);
1809 break;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001810 case KMEMLEAK_NOT_LEAK:
1811 kmemleak_not_leak(log->ptr);
1812 break;
1813 case KMEMLEAK_IGNORE:
1814 kmemleak_ignore(log->ptr);
1815 break;
1816 case KMEMLEAK_SCAN_AREA:
Catalin Marinasc017b4b2009-10-28 13:33:09 +00001817 kmemleak_scan_area(log->ptr, log->size, GFP_KERNEL);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001818 break;
1819 case KMEMLEAK_NO_SCAN:
1820 kmemleak_no_scan(log->ptr);
1821 break;
1822 default:
Catalin Marinas5f790202011-09-28 12:17:03 +01001823 kmemleak_warn("Unknown early log operation: %d\n",
1824 log->op_type);
1825 }
1826
1827 if (atomic_read(&kmemleak_warning)) {
1828 print_log_trace(log);
1829 atomic_set(&kmemleak_warning, 0);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001830 }
1831 }
1832}
1833
1834/*
1835 * Late initialization function.
1836 */
1837static int __init kmemleak_late_init(void)
1838{
1839 struct dentry *dentry;
1840
1841 atomic_set(&kmemleak_initialized, 1);
1842
1843 if (atomic_read(&kmemleak_error)) {
1844 /*
Lucas De Marchi25985ed2011-03-30 22:57:33 -03001845 * Some error occurred and kmemleak was disabled. There is a
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001846 * small chance that kmemleak_disable() was called immediately
1847 * after setting kmemleak_initialized and we may end up with
1848 * two clean-up threads but serialized by scan_mutex.
1849 */
Catalin Marinas179a8102009-09-07 10:14:42 +01001850 schedule_work(&cleanup_work);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001851 return -ENOMEM;
1852 }
1853
1854 dentry = debugfs_create_file("kmemleak", S_IRUGO, NULL, NULL,
1855 &kmemleak_fops);
1856 if (!dentry)
Joe Perchesae281062009-06-23 14:40:26 +01001857 pr_warning("Failed to create the debugfs kmemleak file\n");
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001858 mutex_lock(&scan_mutex);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001859 start_scan_thread();
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001860 mutex_unlock(&scan_mutex);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001861
1862 pr_info("Kernel memory leak detector initialized\n");
1863
1864 return 0;
1865}
1866late_initcall(kmemleak_late_init);