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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
Michel Lespinasse85d3a312012-10-08 16:31:27 -070032 * blocks. The object_tree_root is a red black tree used to look-up
Catalin Marinas3c7b4e62009-06-11 13:22:39 +010033 * 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>
Michel Lespinasse85d3a312012-10-08 16:31:27 -070074#include <linux/rbtree.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
Michel Lespinasse85d3a312012-10-08 16:31:27 -0700135 * rb_node are already protected by the corresponding locks or mutex (see
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100136 * 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;
Michel Lespinasse85d3a312012-10-08 16:31:27 -0700144 struct rb_node rb_node;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100145 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);
Michel Lespinasse85d3a312012-10-08 16:31:27 -0700185/* search tree for object boundaries */
186static struct rb_root object_tree_root = RB_ROOT;
187/* rw_lock protecting the access to object_list and object_tree_root */
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100188static 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",
Michel Lespinasse85d3a312012-10-08 16:31:27 -0700383 object->pointer, object->size);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100384 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/*
Michel Lespinasse85d3a312012-10-08 16:31:27 -0700395 * Look-up a memory block metadata (kmemleak_object) in the object search
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100396 * 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{
Michel Lespinasse85d3a312012-10-08 16:31:27 -0700402 struct rb_node *rb = object_tree_root.rb_node;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100403
Michel Lespinasse85d3a312012-10-08 16:31:27 -0700404 while (rb) {
405 struct kmemleak_object *object =
406 rb_entry(rb, struct kmemleak_object, rb_node);
407 if (ptr < object->pointer)
408 rb = object->rb_node.rb_left;
409 else if (object->pointer + object->size <= ptr)
410 rb = object->rb_node.rb_right;
411 else if (object->pointer == ptr || alias)
412 return object;
413 else {
Catalin Marinas5f790202011-09-28 12:17:03 +0100414 kmemleak_warn("Found object by alias at 0x%08lx\n",
415 ptr);
Catalin Marinasa7686a42010-07-19 11:54:16 +0100416 dump_object_info(object);
Michel Lespinasse85d3a312012-10-08 16:31:27 -0700417 break;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100418 }
Michel Lespinasse85d3a312012-10-08 16:31:27 -0700419 }
420 return NULL;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100421}
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/*
Michel Lespinasse85d3a312012-10-08 16:31:27 -0700474 * Look up an object in the object search tree and increase its use_count.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100475 */
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;
Michel Lespinasse85d3a312012-10-08 16:31:27 -0700519 struct kmemleak_object *object, *parent;
520 struct rb_node **link, *rb_parent;
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
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100563 write_lock_irqsave(&kmemleak_lock, flags);
Luis R. Rodriguez0580a182009-09-08 17:32:34 +0100564
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100565 min_addr = min(min_addr, ptr);
566 max_addr = max(max_addr, ptr + size);
Michel Lespinasse85d3a312012-10-08 16:31:27 -0700567 link = &object_tree_root.rb_node;
568 rb_parent = NULL;
569 while (*link) {
570 rb_parent = *link;
571 parent = rb_entry(rb_parent, struct kmemleak_object, rb_node);
572 if (ptr + size <= parent->pointer)
573 link = &parent->rb_node.rb_left;
574 else if (parent->pointer + parent->size <= ptr)
575 link = &parent->rb_node.rb_right;
576 else {
577 kmemleak_stop("Cannot insert 0x%lx into the object "
578 "search tree (overlaps existing)\n",
579 ptr);
580 kmem_cache_free(object_cache, object);
581 object = parent;
582 spin_lock(&object->lock);
583 dump_object_info(object);
584 spin_unlock(&object->lock);
585 goto out;
586 }
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100587 }
Michel Lespinasse85d3a312012-10-08 16:31:27 -0700588 rb_link_node(&object->rb_node, rb_parent, link);
589 rb_insert_color(&object->rb_node, &object_tree_root);
590
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100591 list_add_tail_rcu(&object->object_list, &object_list);
592out:
593 write_unlock_irqrestore(&kmemleak_lock, flags);
Catalin Marinasfd678962009-08-27 14:29:17 +0100594 return object;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100595}
596
597/*
598 * Remove the metadata (struct kmemleak_object) for a memory block from the
599 * object_list and object_tree_root and decrement its use_count.
600 */
Catalin Marinas53238a62009-07-07 10:33:00 +0100601static void __delete_object(struct kmemleak_object *object)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100602{
603 unsigned long flags;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100604
605 write_lock_irqsave(&kmemleak_lock, flags);
Michel Lespinasse85d3a312012-10-08 16:31:27 -0700606 rb_erase(&object->rb_node, &object_tree_root);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100607 list_del_rcu(&object->object_list);
608 write_unlock_irqrestore(&kmemleak_lock, flags);
609
610 WARN_ON(!(object->flags & OBJECT_ALLOCATED));
Catalin Marinas53238a62009-07-07 10:33:00 +0100611 WARN_ON(atomic_read(&object->use_count) < 2);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100612
613 /*
614 * Locking here also ensures that the corresponding memory block
615 * cannot be freed when it is being scanned.
616 */
617 spin_lock_irqsave(&object->lock, flags);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100618 object->flags &= ~OBJECT_ALLOCATED;
619 spin_unlock_irqrestore(&object->lock, flags);
620 put_object(object);
621}
622
623/*
Catalin Marinas53238a62009-07-07 10:33:00 +0100624 * Look up the metadata (struct kmemleak_object) corresponding to ptr and
625 * delete it.
626 */
627static void delete_object_full(unsigned long ptr)
628{
629 struct kmemleak_object *object;
630
631 object = find_and_get_object(ptr, 0);
632 if (!object) {
633#ifdef DEBUG
634 kmemleak_warn("Freeing unknown object at 0x%08lx\n",
635 ptr);
636#endif
637 return;
638 }
639 __delete_object(object);
640 put_object(object);
641}
642
643/*
644 * Look up the metadata (struct kmemleak_object) corresponding to ptr and
645 * delete it. If the memory block is partially freed, the function may create
646 * additional metadata for the remaining parts of the block.
647 */
648static void delete_object_part(unsigned long ptr, size_t size)
649{
650 struct kmemleak_object *object;
651 unsigned long start, end;
652
653 object = find_and_get_object(ptr, 1);
654 if (!object) {
655#ifdef DEBUG
656 kmemleak_warn("Partially freeing unknown object at 0x%08lx "
657 "(size %zu)\n", ptr, size);
658#endif
659 return;
660 }
661 __delete_object(object);
662
663 /*
664 * Create one or two objects that may result from the memory block
665 * split. Note that partial freeing is only done by free_bootmem() and
666 * this happens before kmemleak_init() is called. The path below is
667 * only executed during early log recording in kmemleak_init(), so
668 * GFP_KERNEL is enough.
669 */
670 start = object->pointer;
671 end = object->pointer + object->size;
672 if (ptr > start)
673 create_object(start, ptr - start, object->min_count,
674 GFP_KERNEL);
675 if (ptr + size < end)
676 create_object(ptr + size, end - ptr - size, object->min_count,
677 GFP_KERNEL);
678
679 put_object(object);
680}
Luis R. Rodrigueza1084c82009-09-04 17:44:52 -0700681
682static void __paint_it(struct kmemleak_object *object, int color)
683{
684 object->min_count = color;
685 if (color == KMEMLEAK_BLACK)
686 object->flags |= OBJECT_NO_SCAN;
687}
688
689static void paint_it(struct kmemleak_object *object, int color)
690{
691 unsigned long flags;
692
693 spin_lock_irqsave(&object->lock, flags);
694 __paint_it(object, color);
695 spin_unlock_irqrestore(&object->lock, flags);
696}
697
698static void paint_ptr(unsigned long ptr, int color)
699{
700 struct kmemleak_object *object;
701
702 object = find_and_get_object(ptr, 0);
703 if (!object) {
704 kmemleak_warn("Trying to color unknown object "
705 "at 0x%08lx as %s\n", ptr,
706 (color == KMEMLEAK_GREY) ? "Grey" :
707 (color == KMEMLEAK_BLACK) ? "Black" : "Unknown");
708 return;
709 }
710 paint_it(object, color);
711 put_object(object);
712}
713
Catalin Marinas53238a62009-07-07 10:33:00 +0100714/*
Holger Hans Peter Freyther145b64b2010-07-22 19:54:13 +0800715 * Mark an object permanently as gray-colored so that it can no longer be
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100716 * reported as a leak. This is used in general to mark a false positive.
717 */
718static void make_gray_object(unsigned long ptr)
719{
Luis R. Rodrigueza1084c82009-09-04 17:44:52 -0700720 paint_ptr(ptr, KMEMLEAK_GREY);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100721}
722
723/*
724 * Mark the object as black-colored so that it is ignored from scans and
725 * reporting.
726 */
727static void make_black_object(unsigned long ptr)
728{
Luis R. Rodrigueza1084c82009-09-04 17:44:52 -0700729 paint_ptr(ptr, KMEMLEAK_BLACK);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100730}
731
732/*
733 * Add a scanning area to the object. If at least one such area is added,
734 * kmemleak will only scan these ranges rather than the whole memory block.
735 */
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000736static void add_scan_area(unsigned long ptr, size_t size, gfp_t gfp)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100737{
738 unsigned long flags;
739 struct kmemleak_object *object;
740 struct kmemleak_scan_area *area;
741
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000742 object = find_and_get_object(ptr, 1);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100743 if (!object) {
Joe Perchesae281062009-06-23 14:40:26 +0100744 kmemleak_warn("Adding scan area to unknown object at 0x%08lx\n",
745 ptr);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100746 return;
747 }
748
Catalin Marinas6ae4bd12011-01-27 10:30:26 +0000749 area = kmem_cache_alloc(scan_area_cache, gfp_kmemleak_mask(gfp));
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100750 if (!area) {
Catalin Marinas6ae4bd12011-01-27 10:30:26 +0000751 pr_warning("Cannot allocate a scan area\n");
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100752 goto out;
753 }
754
755 spin_lock_irqsave(&object->lock, flags);
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000756 if (ptr + size > object->pointer + object->size) {
Joe Perchesae281062009-06-23 14:40:26 +0100757 kmemleak_warn("Scan area larger than object 0x%08lx\n", ptr);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100758 dump_object_info(object);
759 kmem_cache_free(scan_area_cache, area);
760 goto out_unlock;
761 }
762
763 INIT_HLIST_NODE(&area->node);
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000764 area->start = ptr;
765 area->size = size;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100766
767 hlist_add_head(&area->node, &object->area_list);
768out_unlock:
769 spin_unlock_irqrestore(&object->lock, flags);
770out:
771 put_object(object);
772}
773
774/*
775 * Set the OBJECT_NO_SCAN flag for the object corresponding to the give
776 * pointer. Such object will not be scanned by kmemleak but references to it
777 * are searched.
778 */
779static void object_no_scan(unsigned long ptr)
780{
781 unsigned long flags;
782 struct kmemleak_object *object;
783
784 object = find_and_get_object(ptr, 0);
785 if (!object) {
Joe Perchesae281062009-06-23 14:40:26 +0100786 kmemleak_warn("Not scanning unknown object at 0x%08lx\n", ptr);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100787 return;
788 }
789
790 spin_lock_irqsave(&object->lock, flags);
791 object->flags |= OBJECT_NO_SCAN;
792 spin_unlock_irqrestore(&object->lock, flags);
793 put_object(object);
794}
795
796/*
797 * Log an early kmemleak_* call to the early_log buffer. These calls will be
798 * processed later once kmemleak is fully initialized.
799 */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100800static void __init log_early(int op_type, const void *ptr, size_t size,
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000801 int min_count)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100802{
803 unsigned long flags;
804 struct early_log *log;
805
Catalin Marinasb6693002011-09-28 17:22:56 +0100806 if (atomic_read(&kmemleak_error)) {
807 /* kmemleak stopped recording, just count the requests */
808 crt_early_log++;
809 return;
810 }
811
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100812 if (crt_early_log >= ARRAY_SIZE(early_log)) {
Catalin Marinasa9d90582009-06-25 10:16:11 +0100813 kmemleak_disable();
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100814 return;
815 }
816
817 /*
818 * There is no need for locking since the kernel is still in UP mode
819 * at this stage. Disabling the IRQs is enough.
820 */
821 local_irq_save(flags);
822 log = &early_log[crt_early_log];
823 log->op_type = op_type;
824 log->ptr = ptr;
825 log->size = size;
826 log->min_count = min_count;
Catalin Marinas5f790202011-09-28 12:17:03 +0100827 log->trace_len = __save_stack_trace(log->trace);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100828 crt_early_log++;
829 local_irq_restore(flags);
830}
831
832/*
Catalin Marinasfd678962009-08-27 14:29:17 +0100833 * Log an early allocated block and populate the stack trace.
834 */
835static void early_alloc(struct early_log *log)
836{
837 struct kmemleak_object *object;
838 unsigned long flags;
839 int i;
840
841 if (!atomic_read(&kmemleak_enabled) || !log->ptr || IS_ERR(log->ptr))
842 return;
843
844 /*
845 * RCU locking needed to ensure object is not freed via put_object().
846 */
847 rcu_read_lock();
848 object = create_object((unsigned long)log->ptr, log->size,
Tetsuo Handac1bcd6b2009-10-09 10:39:24 +0100849 log->min_count, GFP_ATOMIC);
Catalin Marinas0d5d1aa2009-10-09 10:30:34 +0100850 if (!object)
851 goto out;
Catalin Marinasfd678962009-08-27 14:29:17 +0100852 spin_lock_irqsave(&object->lock, flags);
853 for (i = 0; i < log->trace_len; i++)
854 object->trace[i] = log->trace[i];
855 object->trace_len = log->trace_len;
856 spin_unlock_irqrestore(&object->lock, flags);
Catalin Marinas0d5d1aa2009-10-09 10:30:34 +0100857out:
Catalin Marinasfd678962009-08-27 14:29:17 +0100858 rcu_read_unlock();
859}
860
Catalin Marinasf528f0b2011-09-26 17:12:53 +0100861/*
862 * Log an early allocated block and populate the stack trace.
863 */
864static void early_alloc_percpu(struct early_log *log)
865{
866 unsigned int cpu;
867 const void __percpu *ptr = log->ptr;
868
869 for_each_possible_cpu(cpu) {
870 log->ptr = per_cpu_ptr(ptr, cpu);
871 early_alloc(log);
872 }
873}
874
Catalin Marinasa2b6bf62010-07-19 11:54:17 +0100875/**
876 * kmemleak_alloc - register a newly allocated object
877 * @ptr: pointer to beginning of the object
878 * @size: size of the object
879 * @min_count: minimum number of references to this object. If during memory
880 * scanning a number of references less than @min_count is found,
881 * the object is reported as a memory leak. If @min_count is 0,
882 * the object is never reported as a leak. If @min_count is -1,
883 * the object is ignored (not scanned and not reported as a leak)
884 * @gfp: kmalloc() flags used for kmemleak internal memory allocations
885 *
886 * This function is called from the kernel allocators when a new object
887 * (memory block) is allocated (kmem_cache_alloc, kmalloc, vmalloc etc.).
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100888 */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100889void __ref kmemleak_alloc(const void *ptr, size_t size, int min_count,
890 gfp_t gfp)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100891{
892 pr_debug("%s(0x%p, %zu, %d)\n", __func__, ptr, size, min_count);
893
894 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
895 create_object((unsigned long)ptr, size, min_count, gfp);
896 else if (atomic_read(&kmemleak_early_log))
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000897 log_early(KMEMLEAK_ALLOC, ptr, size, min_count);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100898}
899EXPORT_SYMBOL_GPL(kmemleak_alloc);
900
Catalin Marinasa2b6bf62010-07-19 11:54:17 +0100901/**
Catalin Marinasf528f0b2011-09-26 17:12:53 +0100902 * kmemleak_alloc_percpu - register a newly allocated __percpu object
903 * @ptr: __percpu pointer to beginning of the object
904 * @size: size of the object
905 *
906 * This function is called from the kernel percpu allocator when a new object
907 * (memory block) is allocated (alloc_percpu). It assumes GFP_KERNEL
908 * allocation.
909 */
910void __ref kmemleak_alloc_percpu(const void __percpu *ptr, size_t size)
911{
912 unsigned int cpu;
913
914 pr_debug("%s(0x%p, %zu)\n", __func__, ptr, size);
915
916 /*
917 * Percpu allocations are only scanned and not reported as leaks
918 * (min_count is set to 0).
919 */
920 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
921 for_each_possible_cpu(cpu)
922 create_object((unsigned long)per_cpu_ptr(ptr, cpu),
923 size, 0, GFP_KERNEL);
924 else if (atomic_read(&kmemleak_early_log))
925 log_early(KMEMLEAK_ALLOC_PERCPU, ptr, size, 0);
926}
927EXPORT_SYMBOL_GPL(kmemleak_alloc_percpu);
928
929/**
Catalin Marinasa2b6bf62010-07-19 11:54:17 +0100930 * kmemleak_free - unregister a previously registered object
931 * @ptr: pointer to beginning of the object
932 *
933 * This function is called from the kernel allocators when an object (memory
934 * block) is freed (kmem_cache_free, kfree, vfree etc.).
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100935 */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100936void __ref kmemleak_free(const void *ptr)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100937{
938 pr_debug("%s(0x%p)\n", __func__, ptr);
939
940 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
Catalin Marinas53238a62009-07-07 10:33:00 +0100941 delete_object_full((unsigned long)ptr);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100942 else if (atomic_read(&kmemleak_early_log))
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000943 log_early(KMEMLEAK_FREE, ptr, 0, 0);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100944}
945EXPORT_SYMBOL_GPL(kmemleak_free);
946
Catalin Marinasa2b6bf62010-07-19 11:54:17 +0100947/**
948 * kmemleak_free_part - partially unregister a previously registered object
949 * @ptr: pointer to the beginning or inside the object. This also
950 * represents the start of the range to be freed
951 * @size: size to be unregistered
952 *
953 * This function is called when only a part of a memory block is freed
954 * (usually from the bootmem allocator).
Catalin Marinas53238a62009-07-07 10:33:00 +0100955 */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100956void __ref kmemleak_free_part(const void *ptr, size_t size)
Catalin Marinas53238a62009-07-07 10:33:00 +0100957{
958 pr_debug("%s(0x%p)\n", __func__, ptr);
959
960 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
961 delete_object_part((unsigned long)ptr, size);
962 else if (atomic_read(&kmemleak_early_log))
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000963 log_early(KMEMLEAK_FREE_PART, ptr, size, 0);
Catalin Marinas53238a62009-07-07 10:33:00 +0100964}
965EXPORT_SYMBOL_GPL(kmemleak_free_part);
966
Catalin Marinasa2b6bf62010-07-19 11:54:17 +0100967/**
Catalin Marinasf528f0b2011-09-26 17:12:53 +0100968 * kmemleak_free_percpu - unregister a previously registered __percpu object
969 * @ptr: __percpu pointer to beginning of the object
970 *
971 * This function is called from the kernel percpu allocator when an object
972 * (memory block) is freed (free_percpu).
973 */
974void __ref kmemleak_free_percpu(const void __percpu *ptr)
975{
976 unsigned int cpu;
977
978 pr_debug("%s(0x%p)\n", __func__, ptr);
979
980 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
981 for_each_possible_cpu(cpu)
982 delete_object_full((unsigned long)per_cpu_ptr(ptr,
983 cpu));
984 else if (atomic_read(&kmemleak_early_log))
985 log_early(KMEMLEAK_FREE_PERCPU, ptr, 0, 0);
986}
987EXPORT_SYMBOL_GPL(kmemleak_free_percpu);
988
989/**
Catalin Marinasa2b6bf62010-07-19 11:54:17 +0100990 * kmemleak_not_leak - mark an allocated object as false positive
991 * @ptr: pointer to beginning of the object
992 *
993 * Calling this function on an object will cause the memory block to no longer
994 * be reported as leak and always be scanned.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100995 */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100996void __ref kmemleak_not_leak(const void *ptr)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100997{
998 pr_debug("%s(0x%p)\n", __func__, ptr);
999
1000 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
1001 make_gray_object((unsigned long)ptr);
1002 else if (atomic_read(&kmemleak_early_log))
Catalin Marinasc017b4b2009-10-28 13:33:09 +00001003 log_early(KMEMLEAK_NOT_LEAK, ptr, 0, 0);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001004}
1005EXPORT_SYMBOL(kmemleak_not_leak);
1006
Catalin Marinasa2b6bf62010-07-19 11:54:17 +01001007/**
1008 * kmemleak_ignore - ignore an allocated object
1009 * @ptr: pointer to beginning of the object
1010 *
1011 * Calling this function on an object will cause the memory block to be
1012 * ignored (not scanned and not reported as a leak). This is usually done when
1013 * it is known that the corresponding block is not a leak and does not contain
1014 * any references to other allocated memory blocks.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001015 */
Catalin Marinasa6186d82009-08-27 14:29:16 +01001016void __ref kmemleak_ignore(const void *ptr)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001017{
1018 pr_debug("%s(0x%p)\n", __func__, ptr);
1019
1020 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
1021 make_black_object((unsigned long)ptr);
1022 else if (atomic_read(&kmemleak_early_log))
Catalin Marinasc017b4b2009-10-28 13:33:09 +00001023 log_early(KMEMLEAK_IGNORE, ptr, 0, 0);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001024}
1025EXPORT_SYMBOL(kmemleak_ignore);
1026
Catalin Marinasa2b6bf62010-07-19 11:54:17 +01001027/**
1028 * kmemleak_scan_area - limit the range to be scanned in an allocated object
1029 * @ptr: pointer to beginning or inside the object. This also
1030 * represents the start of the scan area
1031 * @size: size of the scan area
1032 * @gfp: kmalloc() flags used for kmemleak internal memory allocations
1033 *
1034 * This function is used when it is known that only certain parts of an object
1035 * contain references to other objects. Kmemleak will only scan these areas
1036 * reducing the number false negatives.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001037 */
Catalin Marinasc017b4b2009-10-28 13:33:09 +00001038void __ref kmemleak_scan_area(const void *ptr, size_t size, gfp_t gfp)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001039{
1040 pr_debug("%s(0x%p)\n", __func__, ptr);
1041
Tiejun Chenb469d432012-01-11 05:51:10 +00001042 if (atomic_read(&kmemleak_enabled) && ptr && size && !IS_ERR(ptr))
Catalin Marinasc017b4b2009-10-28 13:33:09 +00001043 add_scan_area((unsigned long)ptr, size, gfp);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001044 else if (atomic_read(&kmemleak_early_log))
Catalin Marinasc017b4b2009-10-28 13:33:09 +00001045 log_early(KMEMLEAK_SCAN_AREA, ptr, size, 0);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001046}
1047EXPORT_SYMBOL(kmemleak_scan_area);
1048
Catalin Marinasa2b6bf62010-07-19 11:54:17 +01001049/**
1050 * kmemleak_no_scan - do not scan an allocated object
1051 * @ptr: pointer to beginning of the object
1052 *
1053 * This function notifies kmemleak not to scan the given memory block. Useful
1054 * in situations where it is known that the given object does not contain any
1055 * references to other objects. Kmemleak will not scan such objects reducing
1056 * the number of false negatives.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001057 */
Catalin Marinasa6186d82009-08-27 14:29:16 +01001058void __ref kmemleak_no_scan(const void *ptr)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001059{
1060 pr_debug("%s(0x%p)\n", __func__, ptr);
1061
1062 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
1063 object_no_scan((unsigned long)ptr);
1064 else if (atomic_read(&kmemleak_early_log))
Catalin Marinasc017b4b2009-10-28 13:33:09 +00001065 log_early(KMEMLEAK_NO_SCAN, ptr, 0, 0);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001066}
1067EXPORT_SYMBOL(kmemleak_no_scan);
1068
1069/*
Catalin Marinas04609ccc2009-10-28 13:33:12 +00001070 * Update an object's checksum and return true if it was modified.
1071 */
1072static bool update_checksum(struct kmemleak_object *object)
1073{
1074 u32 old_csum = object->checksum;
1075
1076 if (!kmemcheck_is_obj_initialized(object->pointer, object->size))
1077 return false;
1078
1079 object->checksum = crc32(0, (void *)object->pointer, object->size);
1080 return object->checksum != old_csum;
1081}
1082
1083/*
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001084 * Memory scanning is a long process and it needs to be interruptable. This
Lucas De Marchi25985ed2011-03-30 22:57:33 -03001085 * function checks whether such interrupt condition occurred.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001086 */
1087static int scan_should_stop(void)
1088{
1089 if (!atomic_read(&kmemleak_enabled))
1090 return 1;
1091
1092 /*
1093 * This function may be called from either process or kthread context,
1094 * hence the need to check for both stop conditions.
1095 */
1096 if (current->mm)
1097 return signal_pending(current);
1098 else
1099 return kthread_should_stop();
1100
1101 return 0;
1102}
1103
1104/*
1105 * Scan a memory block (exclusive range) for valid pointers and add those
1106 * found to the gray list.
1107 */
1108static void scan_block(void *_start, void *_end,
Catalin Marinas4b8a9672009-07-07 10:32:56 +01001109 struct kmemleak_object *scanned, int allow_resched)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001110{
1111 unsigned long *ptr;
1112 unsigned long *start = PTR_ALIGN(_start, BYTES_PER_POINTER);
1113 unsigned long *end = _end - (BYTES_PER_POINTER - 1);
1114
1115 for (ptr = start; ptr < end; ptr++) {
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001116 struct kmemleak_object *object;
Pekka Enberg8e019362009-08-27 14:50:00 +01001117 unsigned long flags;
1118 unsigned long pointer;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001119
Catalin Marinas4b8a9672009-07-07 10:32:56 +01001120 if (allow_resched)
1121 cond_resched();
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001122 if (scan_should_stop())
1123 break;
1124
Pekka Enberg8e019362009-08-27 14:50:00 +01001125 /* don't scan uninitialized memory */
1126 if (!kmemcheck_is_obj_initialized((unsigned long)ptr,
1127 BYTES_PER_POINTER))
1128 continue;
1129
1130 pointer = *ptr;
1131
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001132 object = find_and_get_object(pointer, 1);
1133 if (!object)
1134 continue;
1135 if (object == scanned) {
1136 /* self referenced, ignore */
1137 put_object(object);
1138 continue;
1139 }
1140
1141 /*
1142 * Avoid the lockdep recursive warning on object->lock being
1143 * previously acquired in scan_object(). These locks are
1144 * enclosed by scan_mutex.
1145 */
1146 spin_lock_irqsave_nested(&object->lock, flags,
1147 SINGLE_DEPTH_NESTING);
1148 if (!color_white(object)) {
1149 /* non-orphan, ignored or new */
1150 spin_unlock_irqrestore(&object->lock, flags);
1151 put_object(object);
1152 continue;
1153 }
1154
1155 /*
1156 * Increase the object's reference count (number of pointers
1157 * to the memory block). If this count reaches the required
1158 * minimum, the object's color will become gray and it will be
1159 * added to the gray_list.
1160 */
1161 object->count++;
Catalin Marinas0587da42009-10-28 13:33:11 +00001162 if (color_gray(object)) {
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001163 list_add_tail(&object->gray_list, &gray_list);
Catalin Marinas0587da42009-10-28 13:33:11 +00001164 spin_unlock_irqrestore(&object->lock, flags);
1165 continue;
1166 }
1167
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001168 spin_unlock_irqrestore(&object->lock, flags);
Catalin Marinas0587da42009-10-28 13:33:11 +00001169 put_object(object);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001170 }
1171}
1172
1173/*
1174 * Scan a memory block corresponding to a kmemleak_object. A condition is
1175 * that object->use_count >= 1.
1176 */
1177static void scan_object(struct kmemleak_object *object)
1178{
1179 struct kmemleak_scan_area *area;
1180 struct hlist_node *elem;
1181 unsigned long flags;
1182
1183 /*
Uwe Kleine-König21ae2952009-10-07 15:21:09 +02001184 * Once the object->lock is acquired, the corresponding memory block
1185 * cannot be freed (the same lock is acquired in delete_object).
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001186 */
1187 spin_lock_irqsave(&object->lock, flags);
1188 if (object->flags & OBJECT_NO_SCAN)
1189 goto out;
1190 if (!(object->flags & OBJECT_ALLOCATED))
1191 /* already freed object */
1192 goto out;
Catalin Marinasaf986032009-08-27 14:29:12 +01001193 if (hlist_empty(&object->area_list)) {
1194 void *start = (void *)object->pointer;
1195 void *end = (void *)(object->pointer + object->size);
1196
1197 while (start < end && (object->flags & OBJECT_ALLOCATED) &&
1198 !(object->flags & OBJECT_NO_SCAN)) {
1199 scan_block(start, min(start + MAX_SCAN_SIZE, end),
1200 object, 0);
1201 start += MAX_SCAN_SIZE;
1202
1203 spin_unlock_irqrestore(&object->lock, flags);
1204 cond_resched();
1205 spin_lock_irqsave(&object->lock, flags);
1206 }
1207 } else
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001208 hlist_for_each_entry(area, elem, &object->area_list, node)
Catalin Marinasc017b4b2009-10-28 13:33:09 +00001209 scan_block((void *)area->start,
1210 (void *)(area->start + area->size),
1211 object, 0);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001212out:
1213 spin_unlock_irqrestore(&object->lock, flags);
1214}
1215
1216/*
Catalin Marinas04609ccc2009-10-28 13:33:12 +00001217 * Scan the objects already referenced (gray objects). More objects will be
1218 * referenced and, if there are no memory leaks, all the objects are scanned.
1219 */
1220static void scan_gray_list(void)
1221{
1222 struct kmemleak_object *object, *tmp;
1223
1224 /*
1225 * The list traversal is safe for both tail additions and removals
1226 * from inside the loop. The kmemleak objects cannot be freed from
1227 * outside the loop because their use_count was incremented.
1228 */
1229 object = list_entry(gray_list.next, typeof(*object), gray_list);
1230 while (&object->gray_list != &gray_list) {
1231 cond_resched();
1232
1233 /* may add new objects to the list */
1234 if (!scan_should_stop())
1235 scan_object(object);
1236
1237 tmp = list_entry(object->gray_list.next, typeof(*object),
1238 gray_list);
1239
1240 /* remove the object from the list and release it */
1241 list_del(&object->gray_list);
1242 put_object(object);
1243
1244 object = tmp;
1245 }
1246 WARN_ON(!list_empty(&gray_list));
1247}
1248
1249/*
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001250 * Scan data sections and all the referenced memory blocks allocated via the
1251 * kernel's standard allocators. This function must be called with the
1252 * scan_mutex held.
1253 */
1254static void kmemleak_scan(void)
1255{
1256 unsigned long flags;
Catalin Marinas04609ccc2009-10-28 13:33:12 +00001257 struct kmemleak_object *object;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001258 int i;
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001259 int new_leaks = 0;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001260
Catalin Marinasacf49682009-06-26 17:38:29 +01001261 jiffies_last_scan = jiffies;
1262
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001263 /* prepare the kmemleak_object's */
1264 rcu_read_lock();
1265 list_for_each_entry_rcu(object, &object_list, object_list) {
1266 spin_lock_irqsave(&object->lock, flags);
1267#ifdef DEBUG
1268 /*
1269 * With a few exceptions there should be a maximum of
1270 * 1 reference to any object at this point.
1271 */
1272 if (atomic_read(&object->use_count) > 1) {
Joe Perchesae281062009-06-23 14:40:26 +01001273 pr_debug("object->use_count = %d\n",
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001274 atomic_read(&object->use_count));
1275 dump_object_info(object);
1276 }
1277#endif
1278 /* reset the reference count (whiten the object) */
1279 object->count = 0;
1280 if (color_gray(object) && get_object(object))
1281 list_add_tail(&object->gray_list, &gray_list);
1282
1283 spin_unlock_irqrestore(&object->lock, flags);
1284 }
1285 rcu_read_unlock();
1286
1287 /* data/bss scanning */
Catalin Marinas4b8a9672009-07-07 10:32:56 +01001288 scan_block(_sdata, _edata, NULL, 1);
1289 scan_block(__bss_start, __bss_stop, NULL, 1);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001290
1291#ifdef CONFIG_SMP
1292 /* per-cpu sections scanning */
1293 for_each_possible_cpu(i)
1294 scan_block(__per_cpu_start + per_cpu_offset(i),
Catalin Marinas4b8a9672009-07-07 10:32:56 +01001295 __per_cpu_end + per_cpu_offset(i), NULL, 1);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001296#endif
1297
1298 /*
Laura Abbott029aeff2011-11-15 23:49:09 +00001299 * Struct page scanning for each node.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001300 */
Laura Abbott029aeff2011-11-15 23:49:09 +00001301 lock_memory_hotplug();
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001302 for_each_online_node(i) {
1303 pg_data_t *pgdat = NODE_DATA(i);
1304 unsigned long start_pfn = pgdat->node_start_pfn;
1305 unsigned long end_pfn = start_pfn + pgdat->node_spanned_pages;
1306 unsigned long pfn;
1307
1308 for (pfn = start_pfn; pfn < end_pfn; pfn++) {
1309 struct page *page;
1310
1311 if (!pfn_valid(pfn))
1312 continue;
1313 page = pfn_to_page(pfn);
1314 /* only scan if page is in use */
1315 if (page_count(page) == 0)
1316 continue;
Catalin Marinas4b8a9672009-07-07 10:32:56 +01001317 scan_block(page, page + 1, NULL, 1);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001318 }
1319 }
Laura Abbott029aeff2011-11-15 23:49:09 +00001320 unlock_memory_hotplug();
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001321
1322 /*
Catalin Marinas43ed5d62009-09-01 11:12:44 +01001323 * Scanning the task stacks (may introduce false negatives).
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001324 */
1325 if (kmemleak_stack_scan) {
Catalin Marinas43ed5d62009-09-01 11:12:44 +01001326 struct task_struct *p, *g;
1327
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001328 read_lock(&tasklist_lock);
Catalin Marinas43ed5d62009-09-01 11:12:44 +01001329 do_each_thread(g, p) {
1330 scan_block(task_stack_page(p), task_stack_page(p) +
1331 THREAD_SIZE, NULL, 0);
1332 } while_each_thread(g, p);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001333 read_unlock(&tasklist_lock);
1334 }
1335
1336 /*
1337 * Scan the objects already referenced from the sections scanned
Catalin Marinas04609ccc2009-10-28 13:33:12 +00001338 * above.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001339 */
Catalin Marinas04609ccc2009-10-28 13:33:12 +00001340 scan_gray_list();
Catalin Marinas25873622009-07-07 10:32:58 +01001341
1342 /*
Catalin Marinas04609ccc2009-10-28 13:33:12 +00001343 * Check for new or unreferenced objects modified since the previous
1344 * scan and color them gray until the next scan.
Catalin Marinas25873622009-07-07 10:32:58 +01001345 */
1346 rcu_read_lock();
1347 list_for_each_entry_rcu(object, &object_list, object_list) {
1348 spin_lock_irqsave(&object->lock, flags);
Catalin Marinas04609ccc2009-10-28 13:33:12 +00001349 if (color_white(object) && (object->flags & OBJECT_ALLOCATED)
1350 && update_checksum(object) && get_object(object)) {
1351 /* color it gray temporarily */
1352 object->count = object->min_count;
Catalin Marinas25873622009-07-07 10:32:58 +01001353 list_add_tail(&object->gray_list, &gray_list);
1354 }
1355 spin_unlock_irqrestore(&object->lock, flags);
1356 }
1357 rcu_read_unlock();
1358
Catalin Marinas04609ccc2009-10-28 13:33:12 +00001359 /*
1360 * Re-scan the gray list for modified unreferenced objects.
1361 */
1362 scan_gray_list();
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001363
1364 /*
Catalin Marinas04609ccc2009-10-28 13:33:12 +00001365 * If scanning was stopped do not report any new unreferenced objects.
Catalin Marinas17bb9e02009-06-29 17:13:56 +01001366 */
Catalin Marinas04609ccc2009-10-28 13:33:12 +00001367 if (scan_should_stop())
Catalin Marinas17bb9e02009-06-29 17:13:56 +01001368 return;
1369
1370 /*
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001371 * Scanning result reporting.
1372 */
1373 rcu_read_lock();
1374 list_for_each_entry_rcu(object, &object_list, object_list) {
1375 spin_lock_irqsave(&object->lock, flags);
1376 if (unreferenced_object(object) &&
1377 !(object->flags & OBJECT_REPORTED)) {
1378 object->flags |= OBJECT_REPORTED;
1379 new_leaks++;
1380 }
1381 spin_unlock_irqrestore(&object->lock, flags);
1382 }
1383 rcu_read_unlock();
1384
1385 if (new_leaks)
1386 pr_info("%d new suspected memory leaks (see "
1387 "/sys/kernel/debug/kmemleak)\n", new_leaks);
1388
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001389}
1390
1391/*
1392 * Thread function performing automatic memory scanning. Unreferenced objects
1393 * at the end of a memory scan are reported but only the first time.
1394 */
1395static int kmemleak_scan_thread(void *arg)
1396{
1397 static int first_run = 1;
1398
Joe Perchesae281062009-06-23 14:40:26 +01001399 pr_info("Automatic memory scanning thread started\n");
Catalin Marinasbf2a76b2009-07-07 10:32:55 +01001400 set_user_nice(current, 10);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001401
1402 /*
1403 * Wait before the first scan to allow the system to fully initialize.
1404 */
1405 if (first_run) {
1406 first_run = 0;
1407 ssleep(SECS_FIRST_SCAN);
1408 }
1409
1410 while (!kthread_should_stop()) {
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001411 signed long timeout = jiffies_scan_wait;
1412
1413 mutex_lock(&scan_mutex);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001414 kmemleak_scan();
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001415 mutex_unlock(&scan_mutex);
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001416
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001417 /* wait before the next scan */
1418 while (timeout && !kthread_should_stop())
1419 timeout = schedule_timeout_interruptible(timeout);
1420 }
1421
Joe Perchesae281062009-06-23 14:40:26 +01001422 pr_info("Automatic memory scanning thread ended\n");
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001423
1424 return 0;
1425}
1426
1427/*
1428 * Start the automatic memory scanning thread. This function must be called
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001429 * with the scan_mutex held.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001430 */
Luis R. Rodriguez7eb0d5e2009-09-08 17:31:45 +01001431static void start_scan_thread(void)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001432{
1433 if (scan_thread)
1434 return;
1435 scan_thread = kthread_run(kmemleak_scan_thread, NULL, "kmemleak");
1436 if (IS_ERR(scan_thread)) {
Joe Perchesae281062009-06-23 14:40:26 +01001437 pr_warning("Failed to create the scan thread\n");
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001438 scan_thread = NULL;
1439 }
1440}
1441
1442/*
1443 * Stop the automatic memory scanning thread. This function must be called
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001444 * with the scan_mutex held.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001445 */
Luis R. Rodriguez7eb0d5e2009-09-08 17:31:45 +01001446static void stop_scan_thread(void)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001447{
1448 if (scan_thread) {
1449 kthread_stop(scan_thread);
1450 scan_thread = NULL;
1451 }
1452}
1453
1454/*
1455 * Iterate over the object_list and return the first valid object at or after
1456 * the required position with its use_count incremented. The function triggers
1457 * a memory scanning when the pos argument points to the first position.
1458 */
1459static void *kmemleak_seq_start(struct seq_file *seq, loff_t *pos)
1460{
1461 struct kmemleak_object *object;
1462 loff_t n = *pos;
Catalin Marinasb87324d2009-07-07 10:32:58 +01001463 int err;
1464
1465 err = mutex_lock_interruptible(&scan_mutex);
1466 if (err < 0)
1467 return ERR_PTR(err);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001468
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001469 rcu_read_lock();
1470 list_for_each_entry_rcu(object, &object_list, object_list) {
1471 if (n-- > 0)
1472 continue;
1473 if (get_object(object))
1474 goto out;
1475 }
1476 object = NULL;
1477out:
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001478 return object;
1479}
1480
1481/*
1482 * Return the next object in the object_list. The function decrements the
1483 * use_count of the previous object and increases that of the next one.
1484 */
1485static void *kmemleak_seq_next(struct seq_file *seq, void *v, loff_t *pos)
1486{
1487 struct kmemleak_object *prev_obj = v;
1488 struct kmemleak_object *next_obj = NULL;
Michael Wang58fac092012-08-17 12:33:34 +08001489 struct kmemleak_object *obj = prev_obj;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001490
1491 ++(*pos);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001492
Michael Wang58fac092012-08-17 12:33:34 +08001493 list_for_each_entry_continue_rcu(obj, &object_list, object_list) {
Catalin Marinas52c3ce42011-04-27 16:44:26 +01001494 if (get_object(obj)) {
1495 next_obj = obj;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001496 break;
Catalin Marinas52c3ce42011-04-27 16:44:26 +01001497 }
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001498 }
Catalin Marinas288c8572009-07-07 10:32:57 +01001499
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001500 put_object(prev_obj);
1501 return next_obj;
1502}
1503
1504/*
1505 * Decrement the use_count of the last object required, if any.
1506 */
1507static void kmemleak_seq_stop(struct seq_file *seq, void *v)
1508{
Catalin Marinasb87324d2009-07-07 10:32:58 +01001509 if (!IS_ERR(v)) {
1510 /*
1511 * kmemleak_seq_start may return ERR_PTR if the scan_mutex
1512 * waiting was interrupted, so only release it if !IS_ERR.
1513 */
Catalin Marinasf5886c72009-07-29 16:26:57 +01001514 rcu_read_unlock();
Catalin Marinasb87324d2009-07-07 10:32:58 +01001515 mutex_unlock(&scan_mutex);
1516 if (v)
1517 put_object(v);
1518 }
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001519}
1520
1521/*
1522 * Print the information for an unreferenced object to the seq file.
1523 */
1524static int kmemleak_seq_show(struct seq_file *seq, void *v)
1525{
1526 struct kmemleak_object *object = v;
1527 unsigned long flags;
1528
1529 spin_lock_irqsave(&object->lock, flags);
Catalin Marinas288c8572009-07-07 10:32:57 +01001530 if ((object->flags & OBJECT_REPORTED) && unreferenced_object(object))
Catalin Marinas17bb9e02009-06-29 17:13:56 +01001531 print_unreferenced(seq, object);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001532 spin_unlock_irqrestore(&object->lock, flags);
1533 return 0;
1534}
1535
1536static const struct seq_operations kmemleak_seq_ops = {
1537 .start = kmemleak_seq_start,
1538 .next = kmemleak_seq_next,
1539 .stop = kmemleak_seq_stop,
1540 .show = kmemleak_seq_show,
1541};
1542
1543static int kmemleak_open(struct inode *inode, struct file *file)
1544{
Catalin Marinasb87324d2009-07-07 10:32:58 +01001545 return seq_open(file, &kmemleak_seq_ops);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001546}
1547
1548static int kmemleak_release(struct inode *inode, struct file *file)
1549{
Catalin Marinasb87324d2009-07-07 10:32:58 +01001550 return seq_release(inode, file);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001551}
1552
Catalin Marinas189d84e2009-08-27 14:29:15 +01001553static int dump_str_object_info(const char *str)
1554{
1555 unsigned long flags;
1556 struct kmemleak_object *object;
1557 unsigned long addr;
1558
Abhijit Pawardc053732012-12-18 14:23:27 -08001559 if (kstrtoul(str, 0, &addr))
1560 return -EINVAL;
Catalin Marinas189d84e2009-08-27 14:29:15 +01001561 object = find_and_get_object(addr, 0);
1562 if (!object) {
1563 pr_info("Unknown object at 0x%08lx\n", addr);
1564 return -EINVAL;
1565 }
1566
1567 spin_lock_irqsave(&object->lock, flags);
1568 dump_object_info(object);
1569 spin_unlock_irqrestore(&object->lock, flags);
1570
1571 put_object(object);
1572 return 0;
1573}
1574
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001575/*
Luis R. Rodriguez30b37102009-09-04 17:44:51 -07001576 * We use grey instead of black to ensure we can do future scans on the same
1577 * objects. If we did not do future scans these black objects could
1578 * potentially contain references to newly allocated objects in the future and
1579 * we'd end up with false positives.
1580 */
1581static void kmemleak_clear(void)
1582{
1583 struct kmemleak_object *object;
1584 unsigned long flags;
1585
1586 rcu_read_lock();
1587 list_for_each_entry_rcu(object, &object_list, object_list) {
1588 spin_lock_irqsave(&object->lock, flags);
1589 if ((object->flags & OBJECT_REPORTED) &&
1590 unreferenced_object(object))
Luis R. Rodrigueza1084c82009-09-04 17:44:52 -07001591 __paint_it(object, KMEMLEAK_GREY);
Luis R. Rodriguez30b37102009-09-04 17:44:51 -07001592 spin_unlock_irqrestore(&object->lock, flags);
1593 }
1594 rcu_read_unlock();
1595}
1596
1597/*
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001598 * File write operation to configure kmemleak at run-time. The following
1599 * commands can be written to the /sys/kernel/debug/kmemleak file:
1600 * off - disable kmemleak (irreversible)
1601 * stack=on - enable the task stacks scanning
1602 * stack=off - disable the tasks stacks scanning
1603 * scan=on - start the automatic memory scanning thread
1604 * scan=off - stop the automatic memory scanning thread
1605 * scan=... - set the automatic memory scanning period in seconds (0 to
1606 * disable it)
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001607 * scan - trigger a memory scan
Luis R. Rodriguez30b37102009-09-04 17:44:51 -07001608 * clear - mark all current reported unreferenced kmemleak objects as
1609 * grey to ignore printing them
Catalin Marinas189d84e2009-08-27 14:29:15 +01001610 * dump=... - dump information about the object found at the given address
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001611 */
1612static ssize_t kmemleak_write(struct file *file, const char __user *user_buf,
1613 size_t size, loff_t *ppos)
1614{
1615 char buf[64];
1616 int buf_size;
Catalin Marinasb87324d2009-07-07 10:32:58 +01001617 int ret;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001618
Catalin Marinas74341702011-09-29 11:50:07 +01001619 if (!atomic_read(&kmemleak_enabled))
1620 return -EBUSY;
1621
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001622 buf_size = min(size, (sizeof(buf) - 1));
1623 if (strncpy_from_user(buf, user_buf, buf_size) < 0)
1624 return -EFAULT;
1625 buf[buf_size] = 0;
1626
Catalin Marinasb87324d2009-07-07 10:32:58 +01001627 ret = mutex_lock_interruptible(&scan_mutex);
1628 if (ret < 0)
1629 return ret;
1630
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001631 if (strncmp(buf, "off", 3) == 0)
1632 kmemleak_disable();
1633 else if (strncmp(buf, "stack=on", 8) == 0)
1634 kmemleak_stack_scan = 1;
1635 else if (strncmp(buf, "stack=off", 9) == 0)
1636 kmemleak_stack_scan = 0;
1637 else if (strncmp(buf, "scan=on", 7) == 0)
1638 start_scan_thread();
1639 else if (strncmp(buf, "scan=off", 8) == 0)
1640 stop_scan_thread();
1641 else if (strncmp(buf, "scan=", 5) == 0) {
1642 unsigned long secs;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001643
Catalin Marinasb87324d2009-07-07 10:32:58 +01001644 ret = strict_strtoul(buf + 5, 0, &secs);
1645 if (ret < 0)
1646 goto out;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001647 stop_scan_thread();
1648 if (secs) {
1649 jiffies_scan_wait = msecs_to_jiffies(secs * 1000);
1650 start_scan_thread();
1651 }
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001652 } else if (strncmp(buf, "scan", 4) == 0)
1653 kmemleak_scan();
Luis R. Rodriguez30b37102009-09-04 17:44:51 -07001654 else if (strncmp(buf, "clear", 5) == 0)
1655 kmemleak_clear();
Catalin Marinas189d84e2009-08-27 14:29:15 +01001656 else if (strncmp(buf, "dump=", 5) == 0)
1657 ret = dump_str_object_info(buf + 5);
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001658 else
Catalin Marinasb87324d2009-07-07 10:32:58 +01001659 ret = -EINVAL;
1660
1661out:
1662 mutex_unlock(&scan_mutex);
1663 if (ret < 0)
1664 return ret;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001665
1666 /* ignore the rest of the buffer, only one command at a time */
1667 *ppos += size;
1668 return size;
1669}
1670
1671static const struct file_operations kmemleak_fops = {
1672 .owner = THIS_MODULE,
1673 .open = kmemleak_open,
1674 .read = seq_read,
1675 .write = kmemleak_write,
1676 .llseek = seq_lseek,
1677 .release = kmemleak_release,
1678};
1679
1680/*
Catalin Marinas74341702011-09-29 11:50:07 +01001681 * Stop the memory scanning thread and free the kmemleak internal objects if
1682 * no previous scan thread (otherwise, kmemleak may still have some useful
1683 * information on memory leaks).
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001684 */
Catalin Marinas179a8102009-09-07 10:14:42 +01001685static void kmemleak_do_cleanup(struct work_struct *work)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001686{
1687 struct kmemleak_object *object;
Catalin Marinas74341702011-09-29 11:50:07 +01001688 bool cleanup = scan_thread == NULL;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001689
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001690 mutex_lock(&scan_mutex);
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001691 stop_scan_thread();
1692
Catalin Marinas74341702011-09-29 11:50:07 +01001693 if (cleanup) {
1694 rcu_read_lock();
1695 list_for_each_entry_rcu(object, &object_list, object_list)
1696 delete_object_full(object->pointer);
1697 rcu_read_unlock();
1698 }
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001699 mutex_unlock(&scan_mutex);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001700}
1701
Catalin Marinas179a8102009-09-07 10:14:42 +01001702static DECLARE_WORK(cleanup_work, kmemleak_do_cleanup);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001703
1704/*
1705 * Disable kmemleak. No memory allocation/freeing will be traced once this
1706 * function is called. Disabling kmemleak is an irreversible operation.
1707 */
1708static void kmemleak_disable(void)
1709{
1710 /* atomically check whether it was already invoked */
1711 if (atomic_cmpxchg(&kmemleak_error, 0, 1))
1712 return;
1713
1714 /* stop any memory operation tracing */
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001715 atomic_set(&kmemleak_enabled, 0);
1716
1717 /* check whether it is too early for a kernel thread */
1718 if (atomic_read(&kmemleak_initialized))
Catalin Marinas179a8102009-09-07 10:14:42 +01001719 schedule_work(&cleanup_work);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001720
1721 pr_info("Kernel memory leak detector disabled\n");
1722}
1723
1724/*
1725 * Allow boot-time kmemleak disabling (enabled by default).
1726 */
1727static int kmemleak_boot_config(char *str)
1728{
1729 if (!str)
1730 return -EINVAL;
1731 if (strcmp(str, "off") == 0)
1732 kmemleak_disable();
Jason Baronab0155a2010-07-19 11:54:17 +01001733 else if (strcmp(str, "on") == 0)
1734 kmemleak_skip_disable = 1;
1735 else
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001736 return -EINVAL;
1737 return 0;
1738}
1739early_param("kmemleak", kmemleak_boot_config);
1740
Catalin Marinas5f790202011-09-28 12:17:03 +01001741static void __init print_log_trace(struct early_log *log)
1742{
1743 struct stack_trace trace;
1744
1745 trace.nr_entries = log->trace_len;
1746 trace.entries = log->trace;
1747
1748 pr_notice("Early log backtrace:\n");
1749 print_stack_trace(&trace, 2);
1750}
1751
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001752/*
Catalin Marinas20301172009-06-17 18:29:04 +01001753 * Kmemleak initialization.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001754 */
1755void __init kmemleak_init(void)
1756{
1757 int i;
1758 unsigned long flags;
1759
Jason Baronab0155a2010-07-19 11:54:17 +01001760#ifdef CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF
1761 if (!kmemleak_skip_disable) {
Catalin Marinasb370d29e2012-01-20 10:42:40 +00001762 atomic_set(&kmemleak_early_log, 0);
Jason Baronab0155a2010-07-19 11:54:17 +01001763 kmemleak_disable();
1764 return;
1765 }
1766#endif
1767
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001768 jiffies_min_age = msecs_to_jiffies(MSECS_MIN_AGE);
1769 jiffies_scan_wait = msecs_to_jiffies(SECS_SCAN_WAIT * 1000);
1770
1771 object_cache = KMEM_CACHE(kmemleak_object, SLAB_NOLEAKTRACE);
1772 scan_area_cache = KMEM_CACHE(kmemleak_scan_area, SLAB_NOLEAKTRACE);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001773
Catalin Marinasb6693002011-09-28 17:22:56 +01001774 if (crt_early_log >= ARRAY_SIZE(early_log))
1775 pr_warning("Early log buffer exceeded (%d), please increase "
1776 "DEBUG_KMEMLEAK_EARLY_LOG_SIZE\n", crt_early_log);
1777
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001778 /* the kernel is still in UP mode, so disabling the IRQs is enough */
1779 local_irq_save(flags);
Catalin Marinasb6693002011-09-28 17:22:56 +01001780 atomic_set(&kmemleak_early_log, 0);
1781 if (atomic_read(&kmemleak_error)) {
1782 local_irq_restore(flags);
1783 return;
1784 } else
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001785 atomic_set(&kmemleak_enabled, 1);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001786 local_irq_restore(flags);
1787
1788 /*
1789 * This is the point where tracking allocations is safe. Automatic
1790 * scanning is started during the late initcall. Add the early logged
1791 * callbacks to the kmemleak infrastructure.
1792 */
1793 for (i = 0; i < crt_early_log; i++) {
1794 struct early_log *log = &early_log[i];
1795
1796 switch (log->op_type) {
1797 case KMEMLEAK_ALLOC:
Catalin Marinasfd678962009-08-27 14:29:17 +01001798 early_alloc(log);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001799 break;
Catalin Marinasf528f0b2011-09-26 17:12:53 +01001800 case KMEMLEAK_ALLOC_PERCPU:
1801 early_alloc_percpu(log);
1802 break;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001803 case KMEMLEAK_FREE:
1804 kmemleak_free(log->ptr);
1805 break;
Catalin Marinas53238a62009-07-07 10:33:00 +01001806 case KMEMLEAK_FREE_PART:
1807 kmemleak_free_part(log->ptr, log->size);
1808 break;
Catalin Marinasf528f0b2011-09-26 17:12:53 +01001809 case KMEMLEAK_FREE_PERCPU:
1810 kmemleak_free_percpu(log->ptr);
1811 break;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001812 case KMEMLEAK_NOT_LEAK:
1813 kmemleak_not_leak(log->ptr);
1814 break;
1815 case KMEMLEAK_IGNORE:
1816 kmemleak_ignore(log->ptr);
1817 break;
1818 case KMEMLEAK_SCAN_AREA:
Catalin Marinasc017b4b2009-10-28 13:33:09 +00001819 kmemleak_scan_area(log->ptr, log->size, GFP_KERNEL);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001820 break;
1821 case KMEMLEAK_NO_SCAN:
1822 kmemleak_no_scan(log->ptr);
1823 break;
1824 default:
Catalin Marinas5f790202011-09-28 12:17:03 +01001825 kmemleak_warn("Unknown early log operation: %d\n",
1826 log->op_type);
1827 }
1828
1829 if (atomic_read(&kmemleak_warning)) {
1830 print_log_trace(log);
1831 atomic_set(&kmemleak_warning, 0);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001832 }
1833 }
1834}
1835
1836/*
1837 * Late initialization function.
1838 */
1839static int __init kmemleak_late_init(void)
1840{
1841 struct dentry *dentry;
1842
1843 atomic_set(&kmemleak_initialized, 1);
1844
1845 if (atomic_read(&kmemleak_error)) {
1846 /*
Lucas De Marchi25985ed2011-03-30 22:57:33 -03001847 * Some error occurred and kmemleak was disabled. There is a
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001848 * small chance that kmemleak_disable() was called immediately
1849 * after setting kmemleak_initialized and we may end up with
1850 * two clean-up threads but serialized by scan_mutex.
1851 */
Catalin Marinas179a8102009-09-07 10:14:42 +01001852 schedule_work(&cleanup_work);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001853 return -ENOMEM;
1854 }
1855
1856 dentry = debugfs_create_file("kmemleak", S_IRUGO, NULL, NULL,
1857 &kmemleak_fops);
1858 if (!dentry)
Joe Perchesae281062009-06-23 14:40:26 +01001859 pr_warning("Failed to create the debugfs kmemleak file\n");
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001860 mutex_lock(&scan_mutex);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001861 start_scan_thread();
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001862 mutex_unlock(&scan_mutex);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001863
1864 pr_info("Kernel memory leak detector initialized\n");
1865
1866 return 0;
1867}
1868late_initcall(kmemleak_late_init);