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kmemleak.c
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kmemleak.c
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/*
* mm/kmemleak.c
*
* Copyright (C) 2008 ARM Limited
* Written by Catalin Marinas <[email protected]>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
*
* For more information on the algorithm and kmemleak usage, please see
* Documentation/kmemleak.txt.
*
* Notes on locking
* ----------------
*
* The following locks and mutexes are used by kmemleak:
*
* - kmemleak_lock (rwlock): protects the object_list modifications and
* accesses to the object_tree_root. The object_list is the main list
* holding the metadata (struct kmemleak_object) for the allocated memory
* blocks. The object_tree_root is a priority search tree used to look-up
* metadata based on a pointer to the corresponding memory block. The
* kmemleak_object structures are added to the object_list and
* object_tree_root in the create_object() function called from the
* kmemleak_alloc() callback and removed in delete_object() called from the
* kmemleak_free() callback
* - kmemleak_object.lock (spinlock): protects a kmemleak_object. Accesses to
* the metadata (e.g. count) are protected by this lock. Note that some
* members of this structure may be protected by other means (atomic or
* kmemleak_lock). This lock is also held when scanning the corresponding
* memory block to avoid the kernel freeing it via the kmemleak_free()
* callback. This is less heavyweight than holding a global lock like
* kmemleak_lock during scanning
* - scan_mutex (mutex): ensures that only one thread may scan the memory for
* unreferenced objects at a time. The gray_list contains the objects which
* are already referenced or marked as false positives and need to be
* scanned. This list is only modified during a scanning episode when the
* scan_mutex is held. At the end of a scan, the gray_list is always empty.
* Note that the kmemleak_object.use_count is incremented when an object is
* added to the gray_list and therefore cannot be freed. This mutex also
* prevents multiple users of the "kmemleak" debugfs file together with
* modifications to the memory scanning parameters including the scan_thread
* pointer
*
* The kmemleak_object structures have a use_count incremented or decremented
* using the get_object()/put_object() functions. When the use_count becomes
* 0, this count can no longer be incremented and put_object() schedules the
* kmemleak_object freeing via an RCU callback. All calls to the get_object()
* function must be protected by rcu_read_lock() to avoid accessing a freed
* structure.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/sched.h>
#include <linux/jiffies.h>
#include <linux/delay.h>
#include <linux/module.h>
#include <linux/kthread.h>
#include <linux/prio_tree.h>
#include <linux/fs.h>
#include <linux/debugfs.h>
#include <linux/seq_file.h>
#include <linux/cpumask.h>
#include <linux/spinlock.h>
#include <linux/mutex.h>
#include <linux/rcupdate.h>
#include <linux/stacktrace.h>
#include <linux/cache.h>
#include <linux/percpu.h>
#include <linux/hardirq.h>
#include <linux/mmzone.h>
#include <linux/slab.h>
#include <linux/thread_info.h>
#include <linux/err.h>
#include <linux/uaccess.h>
#include <linux/string.h>
#include <linux/nodemask.h>
#include <linux/mm.h>
#include <linux/workqueue.h>
#include <linux/crc32.h>
#include <asm/sections.h>
#include <asm/processor.h>
#include <asm/atomic.h>
#include <linux/kmemcheck.h>
#include <linux/kmemleak.h>
/*
* Kmemleak configuration and common defines.
*/
#define MAX_TRACE 16 /* stack trace length */
#define MSECS_MIN_AGE 5000 /* minimum object age for reporting */
#define SECS_FIRST_SCAN 60 /* delay before the first scan */
#define SECS_SCAN_WAIT 600 /* subsequent auto scanning delay */
#define MAX_SCAN_SIZE 4096 /* maximum size of a scanned block */
#define BYTES_PER_POINTER sizeof(void *)
/* GFP bitmask for kmemleak internal allocations */
#define gfp_kmemleak_mask(gfp) (((gfp) & (GFP_KERNEL | GFP_ATOMIC)) | \
__GFP_NORETRY | __GFP_NOMEMALLOC | \
__GFP_NOWARN)
/* scanning area inside a memory block */
struct kmemleak_scan_area {
struct hlist_node node;
unsigned long start;
size_t size;
};
#define KMEMLEAK_GREY 0
#define KMEMLEAK_BLACK -1
/*
* Structure holding the metadata for each allocated memory block.
* Modifications to such objects should be made while holding the
* object->lock. Insertions or deletions from object_list, gray_list or
* tree_node are already protected by the corresponding locks or mutex (see
* the notes on locking above). These objects are reference-counted
* (use_count) and freed using the RCU mechanism.
*/
struct kmemleak_object {
spinlock_t lock;
unsigned long flags; /* object status flags */
struct list_head object_list;
struct list_head gray_list;
struct prio_tree_node tree_node;
struct rcu_head rcu; /* object_list lockless traversal */
/* object usage count; object freed when use_count == 0 */
atomic_t use_count;
unsigned long pointer;
size_t size;
/* minimum number of a pointers found before it is considered leak */
int min_count;
/* the total number of pointers found pointing to this object */
int count;
/* checksum for detecting modified objects */
u32 checksum;
/* memory ranges to be scanned inside an object (empty for all) */
struct hlist_head area_list;
unsigned long trace[MAX_TRACE];
unsigned int trace_len;
unsigned long jiffies; /* creation timestamp */
pid_t pid; /* pid of the current task */
char comm[TASK_COMM_LEN]; /* executable name */
};
/* flag representing the memory block allocation status */
#define OBJECT_ALLOCATED (1 << 0)
/* flag set after the first reporting of an unreference object */
#define OBJECT_REPORTED (1 << 1)
/* flag set to not scan the object */
#define OBJECT_NO_SCAN (1 << 2)
/* number of bytes to print per line; must be 16 or 32 */
#define HEX_ROW_SIZE 16
/* number of bytes to print at a time (1, 2, 4, 8) */
#define HEX_GROUP_SIZE 1
/* include ASCII after the hex output */
#define HEX_ASCII 1
/* max number of lines to be printed */
#define HEX_MAX_LINES 2
/* the list of all allocated objects */
static LIST_HEAD(object_list);
/* the list of gray-colored objects (see color_gray comment below) */
static LIST_HEAD(gray_list);
/* prio search tree for object boundaries */
static struct prio_tree_root object_tree_root;
/* rw_lock protecting the access to object_list and prio_tree_root */
static DEFINE_RWLOCK(kmemleak_lock);
/* allocation caches for kmemleak internal data */
static struct kmem_cache *object_cache;
static struct kmem_cache *scan_area_cache;
/* set if tracing memory operations is enabled */
static atomic_t kmemleak_enabled = ATOMIC_INIT(0);
/* set in the late_initcall if there were no errors */
static atomic_t kmemleak_initialized = ATOMIC_INIT(0);
/* enables or disables early logging of the memory operations */
static atomic_t kmemleak_early_log = ATOMIC_INIT(1);
/* set if a fata kmemleak error has occurred */
static atomic_t kmemleak_error = ATOMIC_INIT(0);
/* minimum and maximum address that may be valid pointers */
static unsigned long min_addr = ULONG_MAX;
static unsigned long max_addr;
static struct task_struct *scan_thread;
/* used to avoid reporting of recently allocated objects */
static unsigned long jiffies_min_age;
static unsigned long jiffies_last_scan;
/* delay between automatic memory scannings */
static signed long jiffies_scan_wait;
/* enables or disables the task stacks scanning */
static int kmemleak_stack_scan = 1;
/* protects the memory scanning, parameters and debug/kmemleak file access */
static DEFINE_MUTEX(scan_mutex);
/* setting kmemleak=on, will set this var, skipping the disable */
static int kmemleak_skip_disable;
/*
* Early object allocation/freeing logging. Kmemleak is initialized after the
* kernel allocator. However, both the kernel allocator and kmemleak may
* allocate memory blocks which need to be tracked. Kmemleak defines an
* arbitrary buffer to hold the allocation/freeing information before it is
* fully initialized.
*/
/* kmemleak operation type for early logging */
enum {
KMEMLEAK_ALLOC,
KMEMLEAK_FREE,
KMEMLEAK_FREE_PART,
KMEMLEAK_NOT_LEAK,
KMEMLEAK_IGNORE,
KMEMLEAK_SCAN_AREA,
KMEMLEAK_NO_SCAN
};
/*
* Structure holding the information passed to kmemleak callbacks during the
* early logging.
*/
struct early_log {
int op_type; /* kmemleak operation type */
const void *ptr; /* allocated/freed memory block */
size_t size; /* memory block size */
int min_count; /* minimum reference count */
unsigned long trace[MAX_TRACE]; /* stack trace */
unsigned int trace_len; /* stack trace length */
};
/* early logging buffer and current position */
static struct early_log
early_log[CONFIG_DEBUG_KMEMLEAK_EARLY_LOG_SIZE] __initdata;
static int crt_early_log __initdata;
static void kmemleak_disable(void);
/*
* Print a warning and dump the stack trace.
*/
#define kmemleak_warn(x...) do { \
pr_warning(x); \
dump_stack(); \
} while (0)
/*
* Macro invoked when a serious kmemleak condition occurred and cannot be
* recovered from. Kmemleak will be disabled and further allocation/freeing
* tracing no longer available.
*/
#define kmemleak_stop(x...) do { \
kmemleak_warn(x); \
kmemleak_disable(); \
} while (0)
/*
* Printing of the objects hex dump to the seq file. The number of lines to be
* printed is limited to HEX_MAX_LINES to prevent seq file spamming. The
* actual number of printed bytes depends on HEX_ROW_SIZE. It must be called
* with the object->lock held.
*/
static void hex_dump_object(struct seq_file *seq,
struct kmemleak_object *object)
{
const u8 *ptr = (const u8 *)object->pointer;
int i, len, remaining;
unsigned char linebuf[HEX_ROW_SIZE * 5];
/* limit the number of lines to HEX_MAX_LINES */
remaining = len =
min(object->size, (size_t)(HEX_MAX_LINES * HEX_ROW_SIZE));
seq_printf(seq, " hex dump (first %d bytes):\n", len);
for (i = 0; i < len; i += HEX_ROW_SIZE) {
int linelen = min(remaining, HEX_ROW_SIZE);
remaining -= HEX_ROW_SIZE;
hex_dump_to_buffer(ptr + i, linelen, HEX_ROW_SIZE,
HEX_GROUP_SIZE, linebuf, sizeof(linebuf),
HEX_ASCII);
seq_printf(seq, " %s\n", linebuf);
}
}
/*
* Object colors, encoded with count and min_count:
* - white - orphan object, not enough references to it (count < min_count)
* - gray - not orphan, not marked as false positive (min_count == 0) or
* sufficient references to it (count >= min_count)
* - black - ignore, it doesn't contain references (e.g. text section)
* (min_count == -1). No function defined for this color.
* Newly created objects don't have any color assigned (object->count == -1)
* before the next memory scan when they become white.
*/
static bool color_white(const struct kmemleak_object *object)
{
return object->count != KMEMLEAK_BLACK &&
object->count < object->min_count;
}
static bool color_gray(const struct kmemleak_object *object)
{
return object->min_count != KMEMLEAK_BLACK &&
object->count >= object->min_count;
}
/*
* Objects are considered unreferenced only if their color is white, they have
* not be deleted and have a minimum age to avoid false positives caused by
* pointers temporarily stored in CPU registers.
*/
static bool unreferenced_object(struct kmemleak_object *object)
{
return (color_white(object) && object->flags & OBJECT_ALLOCATED) &&
time_before_eq(object->jiffies + jiffies_min_age,
jiffies_last_scan);
}
/*
* Printing of the unreferenced objects information to the seq file. The
* print_unreferenced function must be called with the object->lock held.
*/
static void print_unreferenced(struct seq_file *seq,
struct kmemleak_object *object)
{
int i;
unsigned int msecs_age = jiffies_to_msecs(jiffies - object->jiffies);
seq_printf(seq, "unreferenced object 0x%08lx (size %zu):\n",
object->pointer, object->size);
seq_printf(seq, " comm \"%s\", pid %d, jiffies %lu (age %d.%03ds)\n",
object->comm, object->pid, object->jiffies,
msecs_age / 1000, msecs_age % 1000);
hex_dump_object(seq, object);
seq_printf(seq, " backtrace:\n");
for (i = 0; i < object->trace_len; i++) {
void *ptr = (void *)object->trace[i];
seq_printf(seq, " [<%p>] %pS\n", ptr, ptr);
}
}
/*
* Print the kmemleak_object information. This function is used mainly for
* debugging special cases when kmemleak operations. It must be called with
* the object->lock held.
*/
static void dump_object_info(struct kmemleak_object *object)
{
struct stack_trace trace;
trace.nr_entries = object->trace_len;
trace.entries = object->trace;
pr_notice("Object 0x%08lx (size %zu):\n",
object->tree_node.start, object->size);
pr_notice(" comm \"%s\", pid %d, jiffies %lu\n",
object->comm, object->pid, object->jiffies);
pr_notice(" min_count = %d\n", object->min_count);
pr_notice(" count = %d\n", object->count);
pr_notice(" flags = 0x%lx\n", object->flags);
pr_notice(" checksum = %d\n", object->checksum);
pr_notice(" backtrace:\n");
print_stack_trace(&trace, 4);
}
/*
* Look-up a memory block metadata (kmemleak_object) in the priority search
* tree based on a pointer value. If alias is 0, only values pointing to the
* beginning of the memory block are allowed. The kmemleak_lock must be held
* when calling this function.
*/
static struct kmemleak_object *lookup_object(unsigned long ptr, int alias)
{
struct prio_tree_node *node;
struct prio_tree_iter iter;
struct kmemleak_object *object;
prio_tree_iter_init(&iter, &object_tree_root, ptr, ptr);
node = prio_tree_next(&iter);
if (node) {
object = prio_tree_entry(node, struct kmemleak_object,
tree_node);
if (!alias && object->pointer != ptr) {
pr_warning("Found object by alias at 0x%08lx\n", ptr);
dump_stack();
dump_object_info(object);
object = NULL;
}
} else
object = NULL;
return object;
}
/*
* Increment the object use_count. Return 1 if successful or 0 otherwise. Note
* that once an object's use_count reached 0, the RCU freeing was already
* registered and the object should no longer be used. This function must be
* called under the protection of rcu_read_lock().
*/
static int get_object(struct kmemleak_object *object)
{
return atomic_inc_not_zero(&object->use_count);
}
/*
* RCU callback to free a kmemleak_object.
*/
static void free_object_rcu(struct rcu_head *rcu)
{
struct hlist_node *elem, *tmp;
struct kmemleak_scan_area *area;
struct kmemleak_object *object =
container_of(rcu, struct kmemleak_object, rcu);
/*
* Once use_count is 0 (guaranteed by put_object), there is no other
* code accessing this object, hence no need for locking.
*/
hlist_for_each_entry_safe(area, elem, tmp, &object->area_list, node) {
hlist_del(elem);
kmem_cache_free(scan_area_cache, area);
}
kmem_cache_free(object_cache, object);
}
/*
* Decrement the object use_count. Once the count is 0, free the object using
* an RCU callback. Since put_object() may be called via the kmemleak_free() ->
* delete_object() path, the delayed RCU freeing ensures that there is no
* recursive call to the kernel allocator. Lock-less RCU object_list traversal
* is also possible.
*/
static void put_object(struct kmemleak_object *object)
{
if (!atomic_dec_and_test(&object->use_count))
return;
/* should only get here after delete_object was called */
WARN_ON(object->flags & OBJECT_ALLOCATED);
call_rcu(&object->rcu, free_object_rcu);
}
/*
* Look up an object in the prio search tree and increase its use_count.
*/
static struct kmemleak_object *find_and_get_object(unsigned long ptr, int alias)
{
unsigned long flags;
struct kmemleak_object *object = NULL;
rcu_read_lock();
read_lock_irqsave(&kmemleak_lock, flags);
if (ptr >= min_addr && ptr < max_addr)
object = lookup_object(ptr, alias);
read_unlock_irqrestore(&kmemleak_lock, flags);
/* check whether the object is still available */
if (object && !get_object(object))
object = NULL;
rcu_read_unlock();
return object;
}
/*
* Save stack trace to the given array of MAX_TRACE size.
*/
static int __save_stack_trace(unsigned long *trace)
{
struct stack_trace stack_trace;
stack_trace.max_entries = MAX_TRACE;
stack_trace.nr_entries = 0;
stack_trace.entries = trace;
stack_trace.skip = 2;
save_stack_trace(&stack_trace);
return stack_trace.nr_entries;
}
/*
* Create the metadata (struct kmemleak_object) corresponding to an allocated
* memory block and add it to the object_list and object_tree_root.
*/
static struct kmemleak_object *create_object(unsigned long ptr, size_t size,
int min_count, gfp_t gfp)
{
unsigned long flags;
struct kmemleak_object *object;
struct prio_tree_node *node;
object = kmem_cache_alloc(object_cache, gfp_kmemleak_mask(gfp));
if (!object) {
pr_warning("Cannot allocate a kmemleak_object structure\n");
kmemleak_disable();
return NULL;
}
INIT_LIST_HEAD(&object->object_list);
INIT_LIST_HEAD(&object->gray_list);
INIT_HLIST_HEAD(&object->area_list);
spin_lock_init(&object->lock);
atomic_set(&object->use_count, 1);
object->flags = OBJECT_ALLOCATED;
object->pointer = ptr;
object->size = size;
object->min_count = min_count;
object->count = 0; /* white color initially */
object->jiffies = jiffies;
object->checksum = 0;
/* task information */
if (in_irq()) {
object->pid = 0;
strncpy(object->comm, "hardirq", sizeof(object->comm));
} else if (in_softirq()) {
object->pid = 0;
strncpy(object->comm, "softirq", sizeof(object->comm));
} else {
object->pid = current->pid;
/*
* There is a small chance of a race with set_task_comm(),
* however using get_task_comm() here may cause locking
* dependency issues with current->alloc_lock. In the worst
* case, the command line is not correct.
*/
strncpy(object->comm, current->comm, sizeof(object->comm));
}
/* kernel backtrace */
object->trace_len = __save_stack_trace(object->trace);
INIT_PRIO_TREE_NODE(&object->tree_node);
object->tree_node.start = ptr;
object->tree_node.last = ptr + size - 1;
write_lock_irqsave(&kmemleak_lock, flags);
min_addr = min(min_addr, ptr);
max_addr = max(max_addr, ptr + size);
node = prio_tree_insert(&object_tree_root, &object->tree_node);
/*
* The code calling the kernel does not yet have the pointer to the
* memory block to be able to free it. However, we still hold the
* kmemleak_lock here in case parts of the kernel started freeing
* random memory blocks.
*/
if (node != &object->tree_node) {
kmemleak_stop("Cannot insert 0x%lx into the object search tree "
"(already existing)\n", ptr);
object = lookup_object(ptr, 1);
spin_lock(&object->lock);
dump_object_info(object);
spin_unlock(&object->lock);
goto out;
}
list_add_tail_rcu(&object->object_list, &object_list);
out:
write_unlock_irqrestore(&kmemleak_lock, flags);
return object;
}
/*
* Remove the metadata (struct kmemleak_object) for a memory block from the
* object_list and object_tree_root and decrement its use_count.
*/
static void __delete_object(struct kmemleak_object *object)
{
unsigned long flags;
write_lock_irqsave(&kmemleak_lock, flags);
prio_tree_remove(&object_tree_root, &object->tree_node);
list_del_rcu(&object->object_list);
write_unlock_irqrestore(&kmemleak_lock, flags);
WARN_ON(!(object->flags & OBJECT_ALLOCATED));
WARN_ON(atomic_read(&object->use_count) < 2);
/*
* Locking here also ensures that the corresponding memory block
* cannot be freed when it is being scanned.
*/
spin_lock_irqsave(&object->lock, flags);
object->flags &= ~OBJECT_ALLOCATED;
spin_unlock_irqrestore(&object->lock, flags);
put_object(object);
}
/*
* Look up the metadata (struct kmemleak_object) corresponding to ptr and
* delete it.
*/
static void delete_object_full(unsigned long ptr)
{
struct kmemleak_object *object;
object = find_and_get_object(ptr, 0);
if (!object) {
#ifdef DEBUG
kmemleak_warn("Freeing unknown object at 0x%08lx\n",
ptr);
#endif
return;
}
__delete_object(object);
put_object(object);
}
/*
* Look up the metadata (struct kmemleak_object) corresponding to ptr and
* delete it. If the memory block is partially freed, the function may create
* additional metadata for the remaining parts of the block.
*/
static void delete_object_part(unsigned long ptr, size_t size)
{
struct kmemleak_object *object;
unsigned long start, end;
object = find_and_get_object(ptr, 1);
if (!object) {
#ifdef DEBUG
kmemleak_warn("Partially freeing unknown object at 0x%08lx "
"(size %zu)\n", ptr, size);
#endif
return;
}
__delete_object(object);
/*
* Create one or two objects that may result from the memory block
* split. Note that partial freeing is only done by free_bootmem() and
* this happens before kmemleak_init() is called. The path below is
* only executed during early log recording in kmemleak_init(), so
* GFP_KERNEL is enough.
*/
start = object->pointer;
end = object->pointer + object->size;
if (ptr > start)
create_object(start, ptr - start, object->min_count,
GFP_KERNEL);
if (ptr + size < end)
create_object(ptr + size, end - ptr - size, object->min_count,
GFP_KERNEL);
put_object(object);
}
static void __paint_it(struct kmemleak_object *object, int color)
{
object->min_count = color;
if (color == KMEMLEAK_BLACK)
object->flags |= OBJECT_NO_SCAN;
}
static void paint_it(struct kmemleak_object *object, int color)
{
unsigned long flags;
spin_lock_irqsave(&object->lock, flags);
__paint_it(object, color);
spin_unlock_irqrestore(&object->lock, flags);
}
static void paint_ptr(unsigned long ptr, int color)
{
struct kmemleak_object *object;
object = find_and_get_object(ptr, 0);
if (!object) {
kmemleak_warn("Trying to color unknown object "
"at 0x%08lx as %s\n", ptr,
(color == KMEMLEAK_GREY) ? "Grey" :
(color == KMEMLEAK_BLACK) ? "Black" : "Unknown");
return;
}
paint_it(object, color);
put_object(object);
}
/*
* Mark an object permanently as gray-colored so that it can no longer be
* reported as a leak. This is used in general to mark a false positive.
*/
static void make_gray_object(unsigned long ptr)
{
paint_ptr(ptr, KMEMLEAK_GREY);
}
/*
* Mark the object as black-colored so that it is ignored from scans and
* reporting.
*/
static void make_black_object(unsigned long ptr)
{
paint_ptr(ptr, KMEMLEAK_BLACK);
}
/*
* Add a scanning area to the object. If at least one such area is added,
* kmemleak will only scan these ranges rather than the whole memory block.
*/
static void add_scan_area(unsigned long ptr, size_t size, gfp_t gfp)
{
unsigned long flags;
struct kmemleak_object *object;
struct kmemleak_scan_area *area;
object = find_and_get_object(ptr, 1);
if (!object) {
kmemleak_warn("Adding scan area to unknown object at 0x%08lx\n",
ptr);
return;
}
area = kmem_cache_alloc(scan_area_cache, gfp_kmemleak_mask(gfp));
if (!area) {
pr_warning("Cannot allocate a scan area\n");
goto out;
}
spin_lock_irqsave(&object->lock, flags);
if (ptr + size > object->pointer + object->size) {
kmemleak_warn("Scan area larger than object 0x%08lx\n", ptr);
dump_object_info(object);
kmem_cache_free(scan_area_cache, area);
goto out_unlock;
}
INIT_HLIST_NODE(&area->node);
area->start = ptr;
area->size = size;
hlist_add_head(&area->node, &object->area_list);
out_unlock:
spin_unlock_irqrestore(&object->lock, flags);
out:
put_object(object);
}
/*
* Set the OBJECT_NO_SCAN flag for the object corresponding to the give
* pointer. Such object will not be scanned by kmemleak but references to it
* are searched.
*/
static void object_no_scan(unsigned long ptr)
{
unsigned long flags;
struct kmemleak_object *object;
object = find_and_get_object(ptr, 0);
if (!object) {
kmemleak_warn("Not scanning unknown object at 0x%08lx\n", ptr);
return;
}
spin_lock_irqsave(&object->lock, flags);
object->flags |= OBJECT_NO_SCAN;
spin_unlock_irqrestore(&object->lock, flags);
put_object(object);
}
/*
* Log an early kmemleak_* call to the early_log buffer. These calls will be
* processed later once kmemleak is fully initialized.
*/
static void __init log_early(int op_type, const void *ptr, size_t size,
int min_count)
{
unsigned long flags;
struct early_log *log;
if (crt_early_log >= ARRAY_SIZE(early_log)) {
pr_warning("Early log buffer exceeded, "
"please increase DEBUG_KMEMLEAK_EARLY_LOG_SIZE\n");
kmemleak_disable();
return;
}
/*
* There is no need for locking since the kernel is still in UP mode
* at this stage. Disabling the IRQs is enough.
*/
local_irq_save(flags);
log = &early_log[crt_early_log];
log->op_type = op_type;
log->ptr = ptr;
log->size = size;
log->min_count = min_count;
if (op_type == KMEMLEAK_ALLOC)
log->trace_len = __save_stack_trace(log->trace);
crt_early_log++;
local_irq_restore(flags);
}
/*
* Log an early allocated block and populate the stack trace.
*/
static void early_alloc(struct early_log *log)
{
struct kmemleak_object *object;
unsigned long flags;
int i;
if (!atomic_read(&kmemleak_enabled) || !log->ptr || IS_ERR(log->ptr))
return;
/*
* RCU locking needed to ensure object is not freed via put_object().
*/
rcu_read_lock();
object = create_object((unsigned long)log->ptr, log->size,
log->min_count, GFP_ATOMIC);
if (!object)
goto out;
spin_lock_irqsave(&object->lock, flags);
for (i = 0; i < log->trace_len; i++)
object->trace[i] = log->trace[i];
object->trace_len = log->trace_len;
spin_unlock_irqrestore(&object->lock, flags);
out:
rcu_read_unlock();
}
/**
* kmemleak_alloc - register a newly allocated object
* @ptr: pointer to beginning of the object
* @size: size of the object
* @min_count: minimum number of references to this object. If during memory
* scanning a number of references less than @min_count is found,
* the object is reported as a memory leak. If @min_count is 0,
* the object is never reported as a leak. If @min_count is -1,
* the object is ignored (not scanned and not reported as a leak)
* @gfp: kmalloc() flags used for kmemleak internal memory allocations
*
* This function is called from the kernel allocators when a new object
* (memory block) is allocated (kmem_cache_alloc, kmalloc, vmalloc etc.).
*/
void __ref kmemleak_alloc(const void *ptr, size_t size, int min_count,
gfp_t gfp)
{
pr_debug("%s(0x%p, %zu, %d)\n", __func__, ptr, size, min_count);
if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
create_object((unsigned long)ptr, size, min_count, gfp);
else if (atomic_read(&kmemleak_early_log))
log_early(KMEMLEAK_ALLOC, ptr, size, min_count);
}
EXPORT_SYMBOL_GPL(kmemleak_alloc);
/**
* kmemleak_free - unregister a previously registered object
* @ptr: pointer to beginning of the object
*
* This function is called from the kernel allocators when an object (memory
* block) is freed (kmem_cache_free, kfree, vfree etc.).
*/
void __ref kmemleak_free(const void *ptr)
{
pr_debug("%s(0x%p)\n", __func__, ptr);
if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
delete_object_full((unsigned long)ptr);
else if (atomic_read(&kmemleak_early_log))
log_early(KMEMLEAK_FREE, ptr, 0, 0);
}
EXPORT_SYMBOL_GPL(kmemleak_free);
/**
* kmemleak_free_part - partially unregister a previously registered object
* @ptr: pointer to the beginning or inside the object. This also
* represents the start of the range to be freed
* @size: size to be unregistered
*
* This function is called when only a part of a memory block is freed
* (usually from the bootmem allocator).
*/
void __ref kmemleak_free_part(const void *ptr, size_t size)
{
pr_debug("%s(0x%p)\n", __func__, ptr);
if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
delete_object_part((unsigned long)ptr, size);
else if (atomic_read(&kmemleak_early_log))
log_early(KMEMLEAK_FREE_PART, ptr, size, 0);
}
EXPORT_SYMBOL_GPL(kmemleak_free_part);
/**
* kmemleak_not_leak - mark an allocated object as false positive
* @ptr: pointer to beginning of the object
*
* Calling this function on an object will cause the memory block to no longer
* be reported as leak and always be scanned.
*/
void __ref kmemleak_not_leak(const void *ptr)
{
pr_debug("%s(0x%p)\n", __func__, ptr);
if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
make_gray_object((unsigned long)ptr);
else if (atomic_read(&kmemleak_early_log))
log_early(KMEMLEAK_NOT_LEAK, ptr, 0, 0);
}
EXPORT_SYMBOL(kmemleak_not_leak);
/**
* kmemleak_ignore - ignore an allocated object
* @ptr: pointer to beginning of the object
*
* Calling this function on an object will cause the memory block to be
* ignored (not scanned and not reported as a leak). This is usually done when
* it is known that the corresponding block is not a leak and does not contain
* any references to other allocated memory blocks.
*/
void __ref kmemleak_ignore(const void *ptr)
{
pr_debug("%s(0x%p)\n", __func__, ptr);
if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
make_black_object((unsigned long)ptr);
else if (atomic_read(&kmemleak_early_log))
log_early(KMEMLEAK_IGNORE, ptr, 0, 0);
}
EXPORT_SYMBOL(kmemleak_ignore);
/**
* kmemleak_scan_area - limit the range to be scanned in an allocated object
* @ptr: pointer to beginning or inside the object. This also
* represents the start of the scan area
* @size: size of the scan area
* @gfp: kmalloc() flags used for kmemleak internal memory allocations
*
* This function is used when it is known that only certain parts of an object
* contain references to other objects. Kmemleak will only scan these areas
* reducing the number false negatives.
*/
void __ref kmemleak_scan_area(const void *ptr, size_t size, gfp_t gfp)
{
pr_debug("%s(0x%p)\n", __func__, ptr);
if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
add_scan_area((unsigned long)ptr, size, gfp);
else if (atomic_read(&kmemleak_early_log))
log_early(KMEMLEAK_SCAN_AREA, ptr, size, 0);
}
EXPORT_SYMBOL(kmemleak_scan_area);
/**
* kmemleak_no_scan - do not scan an allocated object
* @ptr: pointer to beginning of the object
*
* This function notifies kmemleak not to scan the given memory block. Useful
* in situations where it is known that the given object does not contain any
* references to other objects. Kmemleak will not scan such objects reducing
* the number of false negatives.
*/
void __ref kmemleak_no_scan(const void *ptr)
{
pr_debug("%s(0x%p)\n", __func__, ptr);
if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
object_no_scan((unsigned long)ptr);
else if (atomic_read(&kmemleak_early_log))
log_early(KMEMLEAK_NO_SCAN, ptr, 0, 0);
}
EXPORT_SYMBOL(kmemleak_no_scan);
/*
* Update an object's checksum and return true if it was modified.
*/
static bool update_checksum(struct kmemleak_object *object)
{
u32 old_csum = object->checksum;
if (!kmemcheck_is_obj_initialized(object->pointer, object->size))