[PATCH v3 2/3] mm: kmemleak: add rbtree and store physical address for objects allocated with PA

Patrick Wang
2022-06-09T12:53:46Z

Add object_phys_tree_root to store the objects allocated with
physical address. Distinguish it from object_tree_root by
OBJECT_PHYS flag or function argument. The physical address
is stored directly in those objects. And remove the unused
kmemleak_not_leak_phys() function.

Suggested-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Patrick Wang <patrick.wang.shcn@gmail.com>
---
Documentation/dev-tools/kmemleak.rst | 1 -
include/linux/kmemleak.h | 4 -
mm/kmemleak.c | 145 +++++++++++++++++----------
3 files changed, 91 insertions(+), 59 deletions(-)

diff --git a/Documentation/dev-tools/kmemleak.rst b/Documentation/dev-tools/kmemleak.rst
index 1c935f41cd3a..5483fd39ef29 100644
--- a/Documentation/dev-tools/kmemleak.rst
+++ b/Documentation/dev-tools/kmemleak.rst
@@ -174,7 +174,6 @@ mapping:

- ``kmemleak_alloc_phys``
- ``kmemleak_free_part_phys``
-- ``kmemleak_not_leak_phys``
- ``kmemleak_ignore_phys``

Dealing with false positives/negatives
diff --git a/include/linux/kmemleak.h b/include/linux/kmemleak.h
index df245d875b1e..6a3cd1bf4680 100644
--- a/include/linux/kmemleak.h
+++ b/include/linux/kmemleak.h
@@ -32,7 +32,6 @@ extern void kmemleak_no_scan(const void *ptr) __ref;
extern void kmemleak_alloc_phys(phys_addr_t phys, size_t size,
gfp_t gfp) __ref;
extern void kmemleak_free_part_phys(phys_addr_t phys, size_t size) __ref;
-extern void kmemleak_not_leak_phys(phys_addr_t phys) __ref;
extern void kmemleak_ignore_phys(phys_addr_t phys) __ref;

static inline void kmemleak_alloc_recursive(const void *ptr, size_t size,
@@ -113,9 +112,6 @@ static inline void kmemleak_alloc_phys(phys_addr_t phys, size_t size,
static inline void kmemleak_free_part_phys(phys_addr_t phys, size_t size)
{
}
-static inline void kmemleak_not_leak_phys(phys_addr_t phys)
-{
-}
static inline void kmemleak_ignore_phys(phys_addr_t phys)
{
}
diff --git a/mm/kmemleak.c b/mm/kmemleak.c
index 85ed719e750d..155f50e1a604 100644
--- a/mm/kmemleak.c
+++ b/mm/kmemleak.c
@@ -14,14 +14,16 @@
* The following locks and mutexes are used by kmemleak:
*
* - kmemleak_lock (raw_spinlock_t): 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 red black 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
+ * accesses to the object_tree_root (or object_phys_tree_root). The
+ * object_list is the main list holding the metadata (struct kmemleak_object)
+ * for the allocated memory blocks. The object_tree_root and object_phys_tree_root
+ * are red black trees used to look-up metadata based on a pointer to the
+ * corresponding memory block. The object_phys_tree_root is for objects
+ * allocated with physical address. The kmemleak_object structures are
+ * added to the object_list and object_tree_root (or object_phys_tree_root)
+ * in the create_object() function called from the kmemleak_alloc() (or
+ * kmemleak_alloc_phys()) callback and removed in delete_object() called from
+ * the kmemleak_free() callback
* - kmemleak_object.lock (raw_spinlock_t): 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
@@ -195,7 +197,9 @@ static int mem_pool_free_count = ARRAY_SIZE(mem_pool);
static LIST_HEAD(mem_pool_free_list);
/* search tree for object boundaries */
static struct rb_root object_tree_root = RB_ROOT;
-/* protecting the access to object_list and object_tree_root */
+/* search tree for object (with OBJECT_PHYS flag) boundaries */
+static struct rb_root object_phys_tree_root = RB_ROOT;
+/* protecting the access to object_list, object_tree_root (or object_phys_tree_root) */
static DEFINE_RAW_SPINLOCK(kmemleak_lock);

/* allocation caches for kmemleak internal data */
@@ -287,6 +291,9 @@ static void hex_dump_object(struct seq_file *seq,
const u8 *ptr = (const u8 *)object->pointer;
size_t len;

+ if (WARN_ON_ONCE(object->flags & OBJECT_PHYS))
+ return;
+
/* limit the number of lines to HEX_MAX_LINES */
len = min_t(size_t, object->size, HEX_MAX_LINES * HEX_ROW_SIZE);

@@ -380,9 +387,11 @@ static void dump_object_info(struct kmemleak_object *object)
* 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)
+static struct kmemleak_object *__lookup_object(unsigned long ptr, int alias,
+ bool is_phys)
{
- struct rb_node *rb = object_tree_root.rb_node;
+ struct rb_node *rb = is_phys ? object_phys_tree_root.rb_node :
+ object_tree_root.rb_node;
unsigned long untagged_ptr = (unsigned long)kasan_reset_tag((void *)ptr);

while (rb) {
@@ -408,6 +417,12 @@ static struct kmemleak_object *lookup_object(unsigned long ptr, int alias)
return NULL;
}

+/* Look-up a kmemleak object which allocated with virtual address. */
+static struct kmemleak_object *lookup_object(unsigned long ptr, int alias)
+{
+ return __lookup_object(ptr, alias, false);
+}
+
/*
* 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
@@ -517,14 +532,15 @@ static void put_object(struct kmemleak_object *object)
/*
* Look up an object in the object search tree and increase its use_count.
*/
-static struct kmemleak_object *find_and_get_object(unsigned long ptr, int alias)
+static struct kmemleak_object *__find_and_get_object(unsigned long ptr, int alias,
+ bool is_phys)
{
unsigned long flags;
struct kmemleak_object *object;

rcu_read_lock();
raw_spin_lock_irqsave(&kmemleak_lock, flags);
- object = lookup_object(ptr, alias);
+ object = __lookup_object(ptr, alias, is_phys);
raw_spin_unlock_irqrestore(&kmemleak_lock, flags);

/* check whether the object is still available */
@@ -535,28 +551,39 @@ static struct kmemleak_object *find_and_get_object(unsigned long ptr, int alias)
return object;
}

+/* Look up and get an object which allocated with virtual address. */
+static struct kmemleak_object *find_and_get_object(unsigned long ptr, int alias)
+{
+ return __find_and_get_object(ptr, alias, false);
+}
+
/*
- * Remove an object from the object_tree_root and object_list. Must be called
- * with the kmemleak_lock held _if_ kmemleak is still enabled.
+ * Remove an object from the object_tree_root (or object_phys_tree_root)
+ * and object_list. Must be called with the kmemleak_lock held _if_ kmemleak
+ * is still enabled.
*/
static void __remove_object(struct kmemleak_object *object)
{
- rb_erase(&object->rb_node, &object_tree_root);
+ rb_erase(&object->rb_node, object->flags & OBJECT_PHYS ?
+ &object_phys_tree_root :
+ &object_tree_root);
list_del_rcu(&object->object_list);
}

/*
* Look up an object in the object search tree and remove it from both
- * object_tree_root and object_list. The returned object's use_count should be
- * at least 1, as initially set by create_object().
+ * object_tree_root (or object_phys_tree_root) and object_list. The
+ * returned object's use_count should be at least 1, as initially set
+ * by create_object().
*/
-static struct kmemleak_object *find_and_remove_object(unsigned long ptr, int alias)
+static struct kmemleak_object *find_and_remove_object(unsigned long ptr, int alias,
+ bool is_phys)
{
unsigned long flags;
struct kmemleak_object *object;

raw_spin_lock_irqsave(&kmemleak_lock, flags);
- object = lookup_object(ptr, alias);
+ object = __lookup_object(ptr, alias, is_phys);
if (object)
__remove_object(object);
raw_spin_unlock_irqrestore(&kmemleak_lock, flags);
@@ -574,7 +601,8 @@ static int __save_stack_trace(unsigned long *trace)

/*
* Create the metadata (struct kmemleak_object) corresponding to an allocated
- * memory block and add it to the object_list and object_tree_root.
+ * memory block and add it to the object_list and object_tree_root (or
+ * object_phys_tree_root).
*/
static struct kmemleak_object *__create_object(unsigned long ptr, size_t size,
int min_count, gfp_t gfp,
@@ -631,9 +659,16 @@ static struct kmemleak_object *__create_object(unsigned long ptr, size_t size,
raw_spin_lock_irqsave(&kmemleak_lock, flags);

untagged_ptr = (unsigned long)kasan_reset_tag((void *)ptr);
- min_addr = min(min_addr, untagged_ptr);
- max_addr = max(max_addr, untagged_ptr + size);
- link = &object_tree_root.rb_node;
+ /*
+ * Only update min_addr and max_addr with object
+ * storing virtual address.
+ */
+ if (!is_phys) {
+ min_addr = min(min_addr, untagged_ptr);
+ max_addr = max(max_addr, untagged_ptr + size);
+ }
+ link = is_phys ? &object_phys_tree_root.rb_node :
+ &object_tree_root.rb_node;
rb_parent = NULL;
while (*link) {
rb_parent = *link;
@@ -657,7 +692,8 @@ static struct kmemleak_object *__create_object(unsigned long ptr, size_t size,
}
}
rb_link_node(&object->rb_node, rb_parent, link);
- rb_insert_color(&object->rb_node, &object_tree_root);
+ rb_insert_color(&object->rb_node, is_phys ? &object_phys_tree_root :
+ &object_tree_root);

list_add_tail_rcu(&object->object_list, &object_list);
out:
@@ -707,7 +743,7 @@ static void delete_object_full(unsigned long ptr)
{
struct kmemleak_object *object;

- object = find_and_remove_object(ptr, 0);
+ object = find_and_remove_object(ptr, 0, false);
if (!object) {
#ifdef DEBUG
kmemleak_warn("Freeing unknown object at 0x%08lx\n",
@@ -723,12 +759,12 @@ static void delete_object_full(unsigned long ptr)
* 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)
+static void delete_object_part(unsigned long ptr, size_t size, bool is_phys)
{
struct kmemleak_object *object;
unsigned long start, end;

- object = find_and_remove_object(ptr, 1);
+ object = find_and_remove_object(ptr, 1, is_phys);
if (!object) {
#ifdef DEBUG
kmemleak_warn("Partially freeing unknown object at 0x%08lx (size %zu)\n",
@@ -746,10 +782,10 @@ static void delete_object_part(unsigned long ptr, size_t size)
end = object->pointer + object->size;
if (ptr > start)
__create_object(start, ptr - start, object->min_count,
- GFP_KERNEL, object->flags & OBJECT_PHYS);
+ GFP_KERNEL, is_phys);
if (ptr + size < end)
__create_object(ptr + size, end - ptr - size, object->min_count,
- GFP_KERNEL, object->flags & OBJECT_PHYS);
+ GFP_KERNEL, is_phys);

__delete_object(object);
}
@@ -770,11 +806,11 @@ static void paint_it(struct kmemleak_object *object, int color)
raw_spin_unlock_irqrestore(&object->lock, flags);
}

-static void paint_ptr(unsigned long ptr, int color)
+static void paint_ptr(unsigned long ptr, int color, bool is_phys)
{
struct kmemleak_object *object;

- object = find_and_get_object(ptr, 0);
+ object = __find_and_get_object(ptr, 0, is_phys);
if (!object) {
kmemleak_warn("Trying to color unknown object at 0x%08lx as %s\n",
ptr,
@@ -792,16 +828,16 @@ static void paint_ptr(unsigned long ptr, int color)
*/
static void make_gray_object(unsigned long ptr)
{
- paint_ptr(ptr, KMEMLEAK_GREY);
+ paint_ptr(ptr, KMEMLEAK_GREY, false);
}

/*
* Mark the object as black-colored so that it is ignored from scans and
* reporting.
*/
-static void make_black_object(unsigned long ptr)
+static void make_black_object(unsigned long ptr, bool is_phys)
{
- paint_ptr(ptr, KMEMLEAK_BLACK);
+ paint_ptr(ptr, KMEMLEAK_BLACK, is_phys);
}

/*
@@ -1007,7 +1043,7 @@ void __ref kmemleak_free_part(const void *ptr, size_t size)
pr_debug("%s(0x%p)\n", __func__, ptr);

if (kmemleak_enabled && ptr && !IS_ERR(ptr))
- delete_object_part((unsigned long)ptr, size);
+ delete_object_part((unsigned long)ptr, size, false);
}
EXPORT_SYMBOL_GPL(kmemleak_free_part);

@@ -1095,7 +1131,7 @@ void __ref kmemleak_ignore(const void *ptr)
pr_debug("%s(0x%p)\n", __func__, ptr);

if (kmemleak_enabled && ptr && !IS_ERR(ptr))
- make_black_object((unsigned long)ptr);
+ make_black_object((unsigned long)ptr, false);
}
EXPORT_SYMBOL(kmemleak_ignore);

@@ -1153,7 +1189,7 @@ void __ref kmemleak_alloc_phys(phys_addr_t phys, size_t size, gfp_t gfp)
* Create object with OBJECT_PHYS flag and
* assume min_count 0.
*/
- create_object_phys((unsigned long)__va(phys), size, 0, gfp);
+ create_object_phys((unsigned long)phys, size, 0, gfp);
}
EXPORT_SYMBOL(kmemleak_alloc_phys);

@@ -1166,22 +1202,12 @@ EXPORT_SYMBOL(kmemleak_alloc_phys);
*/
void __ref kmemleak_free_part_phys(phys_addr_t phys, size_t size)
{
- if (PHYS_PFN(phys) >= min_low_pfn && PHYS_PFN(phys) < max_low_pfn)
- kmemleak_free_part(__va(phys), size);
-}
-EXPORT_SYMBOL(kmemleak_free_part_phys);
+ pr_debug("%s(0x%pa)\n", __func__, &phys);

-/**
- * kmemleak_not_leak_phys - similar to kmemleak_not_leak but taking a physical
- * address argument
- * @phys: physical address of the object
- */
-void __ref kmemleak_not_leak_phys(phys_addr_t phys)
-{
if (PHYS_PFN(phys) >= min_low_pfn && PHYS_PFN(phys) < max_low_pfn)
- kmemleak_not_leak(__va(phys));
+ delete_object_part((unsigned long)phys, size, true);
}
-EXPORT_SYMBOL(kmemleak_not_leak_phys);
+EXPORT_SYMBOL(kmemleak_free_part_phys);

/**
* kmemleak_ignore_phys - similar to kmemleak_ignore but taking a physical
@@ -1190,8 +1216,10 @@ EXPORT_SYMBOL(kmemleak_not_leak_phys);
*/
void __ref kmemleak_ignore_phys(phys_addr_t phys)
{
+ pr_debug("%s(0x%pa)\n", __func__, &phys);
+
if (PHYS_PFN(phys) >= min_low_pfn && PHYS_PFN(phys) < max_low_pfn)
- kmemleak_ignore(__va(phys));
+ make_black_object((unsigned long)phys, true);
}
EXPORT_SYMBOL(kmemleak_ignore_phys);

@@ -1202,6 +1230,9 @@ static bool update_checksum(struct kmemleak_object *object)
{
u32 old_csum = object->checksum;

+ if (WARN_ON_ONCE(object->flags & OBJECT_PHYS))
+ return false;
+
kasan_disable_current();
kcsan_disable_current();
object->checksum = crc32(0, kasan_reset_tag((void *)object->pointer), object->size);
@@ -1355,6 +1386,7 @@ static void scan_object(struct kmemleak_object *object)
{
struct kmemleak_scan_area *area;
unsigned long flags;
+ void *obj_ptr;

/*
* Once the object->lock is acquired, the corresponding memory block
@@ -1366,10 +1398,15 @@ static void scan_object(struct kmemleak_object *object)
if (!(object->flags & OBJECT_ALLOCATED))
/* already freed object */
goto out;
+
+ obj_ptr = object->flags & OBJECT_PHYS ?
+ __va((void *)object->pointer) :
+ (void *)object->pointer;
+
if (hlist_empty(&object->area_list) ||
object->flags & OBJECT_FULL_SCAN) {
- void *start = (void *)object->pointer;
- void *end = (void *)(object->pointer + object->size);
+ void *start = obj_ptr;
+ void *end = obj_ptr + object->size;
void *next;

do {
--
2.25.1