linux-kernel - [PATCH v2 3/4] mm: kmemleak: handle address stored in object based on its type

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Message-Id: <20220603035415.1243913-4-patrick.wang.shcn@gmail.com>
Date:   Fri,  3 Jun 2022 11:54:14 +0800
From:   Patrick Wang <patrick.wang.shcn@...il.com>
To:     catalin.marinas@....com, akpm@...ux-foundation.org
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        yee.lee@...iatek.com, patrick.wang.shcn@...il.com
Subject: [PATCH v2 3/4] mm: kmemleak: handle address stored in object based on its type

Treat the address stored in object in different way according
to its type:

- Only use kasan_reset_tag for virtual address
- Only update min_addr and max_addr for virtual address
- Convert physical address to virtual address in scan_object

Suggested-by: Catalin Marinas <catalin.marinas@....com>
Signed-off-by: Patrick Wang <patrick.wang.shcn@...il.com>
---
 mm/kmemleak.c | 34 ++++++++++++++++++++++++----------
 1 file changed, 24 insertions(+), 10 deletions(-)

diff --git a/mm/kmemleak.c b/mm/kmemleak.c
index 218144392446..246a70b7218f 100644
--- a/mm/kmemleak.c
+++ b/mm/kmemleak.c
@@ -297,7 +297,9 @@ static void hex_dump_object(struct seq_file *seq,
 	warn_or_seq_printf(seq, "  hex dump (first %zu bytes):\n", len);
 	kasan_disable_current();
 	warn_or_seq_hex_dump(seq, DUMP_PREFIX_NONE, HEX_ROW_SIZE,
-			     HEX_GROUP_SIZE, kasan_reset_tag((void *)ptr), len, HEX_ASCII);
+			     HEX_GROUP_SIZE, object->flags & OBJECT_PHYS ? ptr :
+			     kasan_reset_tag((void *)ptr),
+			     len, HEX_ASCII);
 	kasan_enable_current();
 }
 
@@ -389,14 +391,15 @@ static struct kmemleak_object *lookup_object(unsigned long ptr, int alias,
 {
 	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);
+	unsigned long untagged_ptr = is_phys ? ptr : (unsigned long)kasan_reset_tag((void *)ptr);
 
 	while (rb) {
 		struct kmemleak_object *object;
 		unsigned long untagged_objp;
 
 		object = rb_entry(rb, struct kmemleak_object, rb_node);
-		untagged_objp = (unsigned long)kasan_reset_tag((void *)object->pointer);
+		untagged_objp = is_phys ? object->pointer :
+				(unsigned long)kasan_reset_tag((void *)object->pointer);
 
 		if (untagged_ptr < untagged_objp)
 			rb = object->rb_node.rb_left;
@@ -643,16 +646,19 @@ 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);
+	untagged_ptr = is_phys ? ptr : (unsigned long)kasan_reset_tag((void *)ptr);
+	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;
 		parent = rb_entry(rb_parent, struct kmemleak_object, rb_node);
-		untagged_objp = (unsigned long)kasan_reset_tag((void *)parent->pointer);
+		untagged_objp = is_phys ? parent->pointer :
+				(unsigned long)kasan_reset_tag((void *)parent->pointer);
 		if (untagged_ptr + size <= untagged_objp)
 			link = &parent->rb_node.rb_left;
 		else if (untagged_objp + parent->size <= untagged_ptr)
@@ -1202,7 +1208,9 @@ static bool update_checksum(struct kmemleak_object *object)
 
 	kasan_disable_current();
 	kcsan_disable_current();
-	object->checksum = crc32(0, kasan_reset_tag((void *)object->pointer), object->size);
+	object->checksum = crc32(0, object->flags & OBJECT_PHYS ? (void *)object->pointer :
+				    kasan_reset_tag((void *)object->pointer),
+				    object->size);
 	kasan_enable_current();
 	kcsan_enable_current();
 
@@ -1353,6 +1361,7 @@ 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
@@ -1364,10 +1373,15 @@ 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