ANDROID: mm: add get_each_object_track function

Add and export get_each_object_track which helps in
looping through all the slab objects of a page
and gets the track structure of each object, also
make track_item and track structure public, these
will be used by the minidump module to get slab
owner info. Includes commit 0e00d7c46b36 ("ANDROID:
mm/slub: Fix Kasan issue with for_each_object_track")
from android13-5.15 as a bug fix.

Bug: 199236943
Change-Id: Id9922b57053be277f8042ad8199fbbf9faa984ef
Signed-off-by: Vijayanand Jitta <vjitta@codeaurora.org>
Signed-off-by: Jaskaran Singh <quic_jasksing@quicinc.com>

mm/slab.h

@@ -282,6 +282,24 @@ void __kmem_cache_free(struct kmem_cache *s, void *x, unsigned long caller);
 
 gfp_t kmalloc_fix_flags(gfp_t flags);
 
+#ifdef CONFIG_SLUB
+/*
+ * Tracking user of a slab.
+ */
+#define TRACK_ADDRS_COUNT 16
+struct track {
+	unsigned long addr;	/* Called from address */
+#ifdef CONFIG_STACKDEPOT
+	depot_stack_handle_t handle;
+#endif
+	int cpu;		/* Was running on cpu */
+	int pid;		/* Pid context */
+	unsigned long when;	/* When did the operation occur */
+};
+
+enum track_item { TRACK_ALLOC, TRACK_FREE };
+#endif
+
 /* Functions provided by the slab allocators */
 int __kmem_cache_create(struct kmem_cache *, slab_flags_t flags);
 
@@ -399,6 +417,10 @@ DECLARE_STATIC_KEY_FALSE(slub_debug_enabled);
 #endif
 extern void print_tracking(struct kmem_cache *s, void *object);
 long validate_slab_cache(struct kmem_cache *s);
+extern unsigned long get_each_object_track(struct kmem_cache *s,
+		struct page *page, enum track_item alloc,
+		int (*fn)(const struct kmem_cache *, const void *,
+		const struct track *, void *), void *private);
 static inline bool __slub_debug_enabled(void)
 {
 	return static_branch_unlikely(&slub_debug_enabled);
@@ -407,6 +429,15 @@ static inline bool __slub_debug_enabled(void)
 static inline void print_tracking(struct kmem_cache *s, void *object)
 {
 }
+#ifdef CONFIG_SLUB
+static inline unsigned long get_each_object_track(struct kmem_cache *s,
+		struct page *page, enum track_item alloc,
+		int (*fn)(const struct kmem_cache *, const void *,
+		const struct track *, void *), void *private)
+{
+	return 0;
+}
+#endif
 static inline bool __slub_debug_enabled(void)
 {
 	return false;

mm/slub.c

@@ -282,22 +282,6 @@ static inline bool kmem_cache_has_cpu_partial(struct kmem_cache *s)
 /* Use cmpxchg_double */
 #define __CMPXCHG_DOUBLE	((slab_flags_t __force)0x40000000U)
 
-/*
- * Tracking user of a slab.
- */
-#define TRACK_ADDRS_COUNT 16
-struct track {
-	unsigned long addr;	/* Called from address */
-#ifdef CONFIG_STACKDEPOT
-	depot_stack_handle_t handle;
-#endif
-	int cpu;		/* Was running on cpu */
-	int pid;		/* Pid context */
-	unsigned long when;	/* When did the operation occur */
-};
-
-enum track_item { TRACK_ALLOC, TRACK_FREE };
-
 #ifdef CONFIG_SYSFS
 static int sysfs_slab_add(struct kmem_cache *);
 static int sysfs_slab_alias(struct kmem_cache *, const char *);
@@ -725,6 +709,42 @@ static struct track *get_track(struct kmem_cache *s, void *object,
 	return kasan_reset_tag(p + alloc);
 }
 
+/*
+ * This function will be used to loop through all the slab objects in
+ * a page to give track structure for each object, the function fn will
+ * be using this track structure and extract required info into its private
+ * data, the return value will be the number of track structures that are
+ * processed.
+ */
+unsigned long get_each_object_track(struct kmem_cache *s,
+		struct page *page, enum track_item alloc,
+		int (*fn)(const struct kmem_cache *, const void *,
+		const struct track *, void *), void *private)
+{
+	void *p;
+	struct track *t;
+	int ret;
+	unsigned long num_track = 0;
+	struct slab *p_slab = page_slab(page);
+
+	if (!slub_debug || !(s->flags & SLAB_STORE_USER) || !p_slab)
+		return 0;
+
+	slab_lock(p_slab);
+	for_each_object(p, s, page_address(page), p_slab->objects) {
+		t = get_track(s, p, alloc);
+		metadata_access_enable();
+		ret = fn(s, p, t, private);
+		metadata_access_disable();
+		if (ret < 0)
+			break;
+		num_track += 1;
+	}
+	slab_unlock(p_slab);
+	return num_track;
+}
+EXPORT_SYMBOL_NS_GPL(get_each_object_track, MINIDUMP);
+
 #ifdef CONFIG_STACKDEPOT
 static noinline depot_stack_handle_t set_track_prepare(void)
 {