[PATCH 4/6] Protectable Memory

@@ -121,6 +121,9 @@ extern unsigned long gen_pool_alloc_algo(struct gen_pool *, size_t,
 extern void *gen_pool_dma_alloc(struct gen_pool *pool, size_t size,
 		dma_addr_t *dma);
 extern void gen_pool_free(struct gen_pool *, unsigned long, size_t);
+
+extern void gen_pool_flush_chunk(struct gen_pool *pool,
+				 struct gen_pool_chunk *chunk);
 extern void gen_pool_for_each_chunk(struct gen_pool *,
 	void (*)(struct gen_pool *, struct gen_pool_chunk *, void *), void *);
 extern size_t gen_pool_avail(struct gen_pool *);

@@ -0,0 +1,242 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * pmalloc.h: Header for Protectable Memory Allocator
+ *
+ * (C) Copyright 2017 Huawei Technologies Co. Ltd.
+ * Author: Igor Stoppa <igor.stoppa@huawei.com>
+ */
+
+#ifndef _LINUX_PMALLOC_H
+#define _LINUX_PMALLOC_H
+
+
+#include <linux/genalloc.h>
+#include <linux/string.h>
+
+#define PMALLOC_DEFAULT_ALLOC_ORDER (-1)
+
+/*
+ * Library for dynamic allocation of pools of memory that can be,
+ * after initialization, marked as read-only.
+ *
+ * This is intended to complement __read_only_after_init, for those cases
+ * where either it is not possible to know the initialization value before
+ * init is completed, or the amount of data is variable and can be
+ * determined only at run-time.
+ *
+ * ***WARNING***
+ * The user of the API is expected to synchronize:
+ * 1) allocation,
+ * 2) writes to the allocated memory,
+ * 3) write protection of the pool,
+ * 4) freeing of the allocated memory, and
+ * 5) destruction of the pool.
+ *
+ * For a non-threaded scenario, this type of locking is not even required.
+ *
+ * Even if the library were to provide support for locking, point 2)
+ * would still depend on the user taking the lock.
+ */
+
+
+/**
+ * pmalloc_create_pool() - create a new protectable memory pool
+ * @name: the name of the pool, enforced to be unique
+ * @min_alloc_order: log2 of the minimum allocation size obtainable
+ *                   from the pool
+ *
+ * Creates a new (empty) memory pool for allocation of protectable
+ * memory. Memory will be allocated upon request (through pmalloc).
+ *
+ * Return:
+ * * pointer to the new pool	- success
+ * * NULL			- error
+ */
+struct gen_pool *pmalloc_create_pool(const char *name,
+					 int min_alloc_order);
+
+/**
+ * is_pmalloc_object() - validates the existence of an alleged object
+ * @ptr: address of the object
+ * @n: size of the object, in bytes
+ *
+ * Return:
+ * * 0		- the object does not belong to pmalloc
+ * * 1		- the object belongs to pmalloc
+ * * \-1	- the object overlaps pmalloc memory incorrectly
+ */
+int is_pmalloc_object(const void *ptr, const unsigned long n);
+
+/**
+ * pmalloc_prealloc() - tries to allocate a memory chunk of the requested size
+ * @pool: handle to the pool to be used for memory allocation
+ * @size: amount of memory (in bytes) requested
+ *
+ * Prepares a chunk of the requested size.
+ * This is intended to both minimize latency in later memory requests and
+ * avoid sleeping during allocation.
+ * Memory allocated with prealloc is stored in one single chunk, as
+ * opposed to what is allocated on-demand when pmalloc runs out of free
+ * space already existing in the pool and has to invoke vmalloc.
+ * One additional advantage of pre-allocating larger chunks of memory is
+ * that the total slack tends to be smaller.
+ *
+ * Return:
+ * * true	- the vmalloc call was successful
+ * * false	- error
+ */
+bool pmalloc_prealloc(struct gen_pool *pool, size_t size);
+
+/**
+ * pmalloc() - allocate protectable memory from a pool
+ * @pool: handle to the pool to be used for memory allocation
+ * @size: amount of memory (in bytes) requested
+ * @gfp: flags for page allocation
+ *
+ * Allocates memory from an unprotected pool. If the pool doesn't have
+ * enough memory, and the request did not include GFP_ATOMIC, an attempt
+ * is made to add a new chunk of memory to the pool
+ * (a multiple of PAGE_SIZE), in order to fit the new request.
+ * Otherwise, NULL is returned.
+ *
+ * Return:
+ * * pointer to the memory requested	- success
+ * * NULL				- either no memory available or
+ *					  pool already read-only
+ */
+void *pmalloc(struct gen_pool *pool, size_t size, gfp_t gfp);
+
+
+/**
+ * pzalloc() - zero-initialized version of pmalloc
+ * @pool: handle to the pool to be used for memory allocation
+ * @size: amount of memory (in bytes) requested
+ * @gfp: flags for page allocation
+ *
+ * Executes pmalloc, initializing the memory requested to 0,
+ * before returning the pointer to it.
+ *
+ * Return:
+ * * pointer to the memory requested	- success
+ * * NULL				- either no memory available or
+ *					  pool already read-only
+ */
+static inline void *pzalloc(struct gen_pool *pool, size_t size, gfp_t gfp)
+{
+	return pmalloc(pool, size, gfp | __GFP_ZERO);
+}
+
+/**
+ * pmalloc_array() - allocates an array according to the parameters
+ * @pool: handle to the pool to be used for memory allocation
+ * @n: number of elements in the array
+ * @size: amount of memory (in bytes) requested for each element
+ * @flags: flags for page allocation
+ *
+ * Executes pmalloc, if it has a chance to succeed.
+ *
+ * Return:
+ * * the pmalloc result	- success
+ * * NULL		- error
+ */
+static inline void *pmalloc_array(struct gen_pool *pool, size_t n,
+				  size_t size, gfp_t flags)
+{
+	if (unlikely(!(pool && n && size)))
+		return NULL;
+	return pmalloc(pool, n * size, flags);
+}
+
+/**
+ * pcalloc() - allocates a 0-initialized array according to the parameters
+ * @pool: handle to the pool to be used for memory allocation
+ * @n: number of elements in the array
+ * @size: amount of memory (in bytes) requested
+ * @flags: flags for page allocation
+ *
+ * Executes pmalloc_array, if it has a chance to succeed.
+ *
+ * Return:
+ * * the pmalloc result	- success
+ * * NULL		- error
+ */
+static inline void *pcalloc(struct gen_pool *pool, size_t n,
+			    size_t size, gfp_t flags)
+{
+	return pmalloc_array(pool, n, size, flags | __GFP_ZERO);
+}
+
+/**
+ * pstrdup() - duplicate a string, using pmalloc as allocator
+ * @pool: handle to the pool to be used for memory allocation
+ * @s: string to duplicate
+ * @gfp: flags for page allocation
+ *
+ * Generates a copy of the given string, allocating sufficient memory
+ * from the given pmalloc pool.
+ *
+ * Return:
+ * * pointer to the replica	- success
+ * * NULL			- error
+ */
+static inline char *pstrdup(struct gen_pool *pool, const char *s, gfp_t gfp)
+{
+	size_t len;
+	char *buf;
+
+	if (unlikely(pool == NULL || s == NULL))
+		return NULL;
+
+	len = strlen(s) + 1;
+	buf = pmalloc(pool, len, gfp);
+	if (likely(buf))
+		strncpy(buf, s, len);
+	return buf;
+}
+
+/**
+ * pmalloc_protect_pool() - turn a read/write pool read-only
+ * @pool: the pool to protect
+ *
+ * Write-protects all the memory chunks assigned to the pool.
+ * This prevents any further allocation.
+ *
+ * Return:
+ * * 0		- success
+ * * -EINVAL	- error
+ */
+int pmalloc_protect_pool(struct gen_pool *pool);
+
+/**
+ * pfree() - mark as unused memory that was previously in use
+ * @pool: handle to the pool to be used for memory allocation
+ * @addr: the beginning of the memory area to be freed
+ *
+ * The behavior of pfree is different, depending on the state of the
+ * protection.
+ * If the pool is not yet protected, the memory is marked as unused and
+ * will be available for further allocations.
+ * If the pool is already protected, the memory is marked as unused, but
+ * it will still be impossible to perform further allocation, because of
+ * the existing protection.
+ * The freed memory, in this case, will be truly released only when the
+ * pool is destroyed.
+ */
+static inline void pfree(struct gen_pool *pool, const void *addr)
+{
+	gen_pool_free(pool, (unsigned long)addr, 0);
+}
+
+/**
+ * pmalloc_destroy_pool() - destroys a pool and all the associated memory
+ * @pool: the pool to destroy
+ *
+ * All the memory that was allocated through pmalloc in the pool will be freed.
+ *
+ * Return:
+ * * 0		- success
+ * * -EINVAL	- error
+ */
+int pmalloc_destroy_pool(struct gen_pool *pool);
+
+#endif

@@ -20,6 +20,7 @@ struct notifier_block;		/* in notifier.h */
 #define VM_UNINITIALIZED	0x00000020	/* vm_struct is not fully initialized */
 #define VM_NO_GUARD		0x00000040      /* don't add guard page */
 #define VM_KASAN		0x00000080      /* has allocated kasan shadow memory */
+#define VM_PMALLOC		0x00000100	/* pmalloc area - see docs */
 /* bits [20..32] reserved for arch specific ioremap internals */
 
 /*

@@ -625,6 +625,33 @@ void gen_pool_free(struct gen_pool *pool, unsigned long addr, size_t size)
 }
 EXPORT_SYMBOL(gen_pool_free);
 
+
+/**
+ * gen_pool_flush_chunk() - drops all the allocations from a specific chunk
+ * @pool:	the generic memory pool
+ * @chunk:	The chunk to wipe clear.
+ *
+ * This is meant to be called only while destroying a pool. It's up to the
+ * caller to avoid races, but really, at this point the pool should have
+ * already been retired and it should have become unavailable for any other
+ * sort of operation.
+ */
+void gen_pool_flush_chunk(struct gen_pool *pool,
+			  struct gen_pool_chunk *chunk)
+{
+	size_t size;
+
+	if (unlikely(!(pool && chunk)))
+		return;
+
+	size = chunk->end_addr + 1 - chunk->start_addr;
+	memset(chunk->entries, 0,
+	       DIV_ROUND_UP(size >> pool->min_alloc_order * BITS_PER_ENTRY,
+			    BITS_PER_BYTE));
+	atomic_long_set(&chunk->avail, size);
+}
+
+
 /**
  * gen_pool_for_each_chunk() - call func for every chunk of generic memory pool
  * @pool:	the generic memory pool

@@ -760,3 +760,9 @@ config GUP_BENCHMARK
 	  performance of get_user_pages_fast().
 
 	  See tools/testing/selftests/vm/gup_benchmark.c
+
+config PROTECTABLE_MEMORY
+    bool
+    depends on ARCH_HAS_SET_MEMORY
+    select GENERIC_ALLOCATOR
+    default y

@@ -65,6 +65,7 @@ obj-$(CONFIG_SPARSEMEM)	+= sparse.o
 obj-$(CONFIG_SPARSEMEM_VMEMMAP) += sparse-vmemmap.o
 obj-$(CONFIG_SLOB) += slob.o
 obj-$(CONFIG_MMU_NOTIFIER) += mmu_notifier.o
+obj-$(CONFIG_PROTECTABLE_MEMORY) += pmalloc.o
 obj-$(CONFIG_KSM) += ksm.o
 obj-$(CONFIG_PAGE_POISONING) += page_poison.o
 obj-$(CONFIG_SLAB) += slab.o

@@ -0,0 +1,499 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * pmalloc.c: Protectable Memory Allocator
+ *
+ * (C) Copyright 2017 Huawei Technologies Co. Ltd.
+ * Author: Igor Stoppa <igor.stoppa@huawei.com>
+ */
+
+#include <linux/printk.h>
+#include <linux/init.h>
+#include <linux/mm.h>
+#include <linux/vmalloc.h>
+#include <linux/genalloc.h>
+#include <linux/kernel.h>
+#include <linux/log2.h>
+#include <linux/slab.h>
+#include <linux/device.h>
+#include <linux/atomic.h>
+#include <linux/rculist.h>
+#include <linux/set_memory.h>
+#include <asm/cacheflush.h>
+#include <asm/page.h>
+
+#include <linux/pmalloc.h>
+/*
+ * pmalloc_data contains the data specific to a pmalloc pool,
+ * in a format compatible with the design of gen_alloc.
+ * Some of the fields are used for exposing the corresponding parameter
+ * to userspace, through sysfs.
+ */
+struct pmalloc_data {
+	struct gen_pool *pool;  /* Link back to the associated pool. */
+	bool protected;     /* Status of the pool: RO or RW. */
+	struct kobj_attribute attr_protected; /* Sysfs attribute. */
+	struct kobj_attribute attr_avail;     /* Sysfs attribute. */
+	struct kobj_attribute attr_size;      /* Sysfs attribute. */
+	struct kobj_attribute attr_chunks;    /* Sysfs attribute. */
+	struct kobject *pool_kobject;
+	struct list_head node; /* list of pools */
+};
+
+static LIST_HEAD(pmalloc_final_list);
+static LIST_HEAD(pmalloc_tmp_list);
+static struct list_head *pmalloc_list = &pmalloc_tmp_list;
+static DEFINE_MUTEX(pmalloc_mutex);
+static struct kobject *pmalloc_kobject;
+
+static ssize_t pmalloc_pool_show_protected(struct kobject *dev,
+					   struct kobj_attribute *attr,
+					   char *buf)
+{
+	struct pmalloc_data *data;
+
+	data = container_of(attr, struct pmalloc_data, attr_protected);
+	if (data->protected)
+		return sprintf(buf, "protected\n");
+	else
+		return sprintf(buf, "unprotected\n");
+}
+
+static ssize_t pmalloc_pool_show_avail(struct kobject *dev,
+				       struct kobj_attribute *attr,
+				       char *buf)
+{
+	struct pmalloc_data *data;
+
+	data = container_of(attr, struct pmalloc_data, attr_avail);
+	return sprintf(buf, "%lu\n",
+		       (unsigned long)gen_pool_avail(data->pool));
+}
+
+static ssize_t pmalloc_pool_show_size(struct kobject *dev,
+				      struct kobj_attribute *attr,
+				      char *buf)
+{
+	struct pmalloc_data *data;
+
+	data = container_of(attr, struct pmalloc_data, attr_size);
+	return sprintf(buf, "%lu\n",
+		       (unsigned long)gen_pool_size(data->pool));
+}
+
+static void pool_chunk_number(struct gen_pool *pool,
+			      struct gen_pool_chunk *chunk, void *data)
+{
+	unsigned long *counter = data;
+
+	(*counter)++;
+}
+
+static ssize_t pmalloc_pool_show_chunks(struct kobject *dev,
+					struct kobj_attribute *attr,
+					char *buf)
+{
+	struct pmalloc_data *data;
+	unsigned long chunks_num = 0;
+
+	data = container_of(attr, struct pmalloc_data, attr_chunks);
+	gen_pool_for_each_chunk(data->pool, pool_chunk_number, &chunks_num);
+	return sprintf(buf, "%lu\n", chunks_num);
+}
+
+/* Exposes the pool and its attributes through sysfs. */
+static struct kobject *pmalloc_connect(struct pmalloc_data *data)
+{
+	const struct attribute *attrs[] = {
+		&data->attr_protected.attr,
+		&data->attr_avail.attr,
+		&data->attr_size.attr,
+		&data->attr_chunks.attr,
+		NULL
+	};
+	struct kobject *kobj;
+
+	kobj = kobject_create_and_add(data->pool->name, pmalloc_kobject);
+	if (unlikely(!kobj))
+		return NULL;
+
+	if (unlikely(sysfs_create_files(kobj, attrs) < 0)) {
+		kobject_put(kobj);
+		kobj = NULL;
+	}
+	return kobj;
+}
+
+/* Removes the pool and its attributes from sysfs. */
+static void pmalloc_disconnect(struct pmalloc_data *data,
+			       struct kobject *kobj)
+{
+	const struct attribute *attrs[] = {
+		&data->attr_protected.attr,
+		&data->attr_avail.attr,
+		&data->attr_size.attr,
+		&data->attr_chunks.attr,
+		NULL
+	};
+
+	sysfs_remove_files(kobj, attrs);
+	kobject_put(kobj);
+}
+
+/* Declares an attribute of the pool. */
+#define pmalloc_attr_init(data, attr_name) \
+do { \
+	sysfs_attr_init(&data->attr_##attr_name.attr); \
+	data->attr_##attr_name.attr.name = #attr_name; \
+	data->attr_##attr_name.attr.mode = VERIFY_OCTAL_PERMISSIONS(0400); \
+	data->attr_##attr_name.show = pmalloc_pool_show_##attr_name; \
+} while (0)
+
+struct gen_pool *pmalloc_create_pool(const char *name, int min_alloc_order)
+{
+	struct gen_pool *pool;
+	const char *pool_name;
+	struct pmalloc_data *data;
+
+	if (!name) {
+		WARN_ON(1);
+		return NULL;
+	}
+
+	if (min_alloc_order < 0)
+		min_alloc_order = ilog2(sizeof(unsigned long));
+
+	pool = gen_pool_create(min_alloc_order, NUMA_NO_NODE);
+	if (unlikely(!pool))
+		return NULL;
+
+	mutex_lock(&pmalloc_mutex);
+	list_for_each_entry(data, pmalloc_list, node)
+		if (!strcmp(name, data->pool->name))
+			goto same_name_err;
+
+	pool_name = kstrdup(name, GFP_KERNEL);
+	if (unlikely(!pool_name))
+		goto name_alloc_err;
+
+	data = kzalloc(sizeof(struct pmalloc_data), GFP_KERNEL);
+	if (unlikely(!data))
+		goto data_alloc_err;
+
+	data->protected = false;
+	data->pool = pool;
+	pmalloc_attr_init(data, protected);
+	pmalloc_attr_init(data, avail);
+	pmalloc_attr_init(data, size);
+	pmalloc_attr_init(data, chunks);
+	pool->data = data;
+	pool->name = pool_name;
+
+	list_add(&data->node, pmalloc_list);
+	if (pmalloc_list == &pmalloc_final_list)
+		data->pool_kobject = pmalloc_connect(data);
+	mutex_unlock(&pmalloc_mutex);
+	return pool;
+
+data_alloc_err:
+	kfree(pool_name);
+name_alloc_err:
+same_name_err:
+	mutex_unlock(&pmalloc_mutex);
+	gen_pool_destroy(pool);
+	return NULL;
+}
+
+static inline int check_alloc_params(struct gen_pool *pool, size_t req_size)
+{
+	struct pmalloc_data *data;
+
+	if (unlikely(!req_size || !pool))
+		return -1;
+
+	data = pool->data;
+
+	if (data == NULL)
+		return -1;
+
+	if (unlikely(data->protected)) {
+		WARN_ON(1);
+		return -1;
+	}
+	return 0;
+}
+
+
+static inline bool chunk_tagging(void *chunk, bool tag)
+{
+	struct vm_struct *area;
+	struct page *page;
+
+	if (!is_vmalloc_addr(chunk))
+		return false;
+
+	page = vmalloc_to_page(chunk);
+	if (unlikely(!page))
+		return false;
+
+	area = page->area;
+	if (tag)
+		area->flags |= VM_PMALLOC;
+	else
+		area->flags &= ~VM_PMALLOC;
+	return true;
+}
+
+
+static inline bool tag_chunk(void *chunk)
+{
+	return chunk_tagging(chunk, true);
+}
+
+
+static inline bool untag_chunk(void *chunk)
+{
+	return chunk_tagging(chunk, false);
+}
+
+enum {
+	INVALID_PMALLOC_OBJECT = -1,
+	NOT_PMALLOC_OBJECT = 0,
+	VALID_PMALLOC_OBJECT = 1,
+};
+
+int is_pmalloc_object(const void *ptr, const unsigned long n)
+{
+	struct vm_struct *area;
+	struct page *page;
+	unsigned long area_start;
+	unsigned long area_end;
+	unsigned long object_start;
+	unsigned long object_end;
+
+
+	/*
+	 * is_pmalloc_object gets called pretty late, so chances are high
+	 * that the object is indeed of vmalloc type
+	 */
+	if (unlikely(!is_vmalloc_addr(ptr)))
+		return NOT_PMALLOC_OBJECT;
+
+	page = vmalloc_to_page(ptr);
+	if (unlikely(!page))
+		return NOT_PMALLOC_OBJECT;
+
+	area = page->area;
+
+	if (likely(!(area->flags & VM_PMALLOC)))
+		return NOT_PMALLOC_OBJECT;
+
+	area_start = (unsigned long)area->addr;
+	area_end = area_start + area->nr_pages * PAGE_SIZE - 1;
+	object_start = (unsigned long)ptr;
+	object_end = object_start + n - 1;
+
+	if (likely((area_start <= object_start) &&
+		   (object_end <= area_end)))
+		return VALID_PMALLOC_OBJECT;
+	else
+		return INVALID_PMALLOC_OBJECT;
+}
+
+
+bool pmalloc_prealloc(struct gen_pool *pool, size_t size)
+{
+	void *chunk;
+	size_t chunk_size;
+	bool add_error;
+
+	if (check_alloc_params(pool, size))
+		return false;
+
+	/* Expand pool */
+	chunk_size = roundup(size, PAGE_SIZE);
+	chunk = vmalloc(chunk_size);
+	if (unlikely(chunk == NULL))
+		return false;
+
+	/* Locking is already done inside gen_pool_add */
+	add_error = gen_pool_add(pool, (unsigned long)chunk, chunk_size,
+				 NUMA_NO_NODE);
+	if (unlikely(add_error != 0))
+		goto abort;
+
+	return true;
+abort:
+	vfree_atomic(chunk);
+	return false;
+
+}
+
+void *pmalloc(struct gen_pool *pool, size_t size, gfp_t gfp)
+{
+	void *chunk;
+	size_t chunk_size;
+	bool add_error;
+	unsigned long retval;
+
+	if (check_alloc_params(pool, size))
+		return NULL;
+
+retry_alloc_from_pool:
+	retval = gen_pool_alloc(pool, size);
+	if (retval)
+		goto return_allocation;
+
+	if (unlikely((gfp & __GFP_ATOMIC))) {
+		if (unlikely((gfp & __GFP_NOFAIL)))
+			goto retry_alloc_from_pool;
+		else
+			return NULL;
+	}
+
+	/* Expand pool */
+	chunk_size = roundup(size, PAGE_SIZE);
+	chunk = vmalloc(chunk_size);
+	if (unlikely(!chunk)) {
+		if (unlikely((gfp & __GFP_NOFAIL)))
+			goto retry_alloc_from_pool;
+		else
+			return NULL;
+	}
+	if (unlikely(!tag_chunk(chunk)))
+		goto free;
+
+	/* Locking is already done inside gen_pool_add */
+	add_error = gen_pool_add(pool, (unsigned long)chunk, chunk_size,
+				 NUMA_NO_NODE);
+	if (unlikely(add_error))
+		goto abort;
+
+	retval = gen_pool_alloc(pool, size);
+	if (retval) {
+return_allocation:
+		*(size_t *)retval = size;
+		if (gfp & __GFP_ZERO)
+			memset((void *)retval, 0, size);
+		return (void *)retval;
+	}
+	/*
+	 * Here there is no test for __GFP_NO_FAIL because, in case of
+	 * concurrent allocation, one thread might add a chunk to the
+	 * pool and this memory could be allocated by another thread,
+	 * before the first thread gets a chance to use it.
+	 * As long as vmalloc succeeds, it's ok to retry.
+	 */
+	goto retry_alloc_from_pool;
+abort:
+	untag_chunk(chunk);
+free:
+	vfree_atomic(chunk);
+	return NULL;
+}
+
+static void pmalloc_chunk_set_protection(struct gen_pool *pool,
+
+					 struct gen_pool_chunk *chunk,
+					 void *data)
+{
+	const bool *flag = data;
+	size_t chunk_size = chunk->end_addr + 1 - chunk->start_addr;
+	unsigned long pages = chunk_size / PAGE_SIZE;
+
+	BUG_ON(chunk_size & (PAGE_SIZE - 1));
+
+	if (*flag)
+		set_memory_ro(chunk->start_addr, pages);
+	else
+		set_memory_rw(chunk->start_addr, pages);
+}
+
+static int pmalloc_pool_set_protection(struct gen_pool *pool, bool protection)
+{
+	struct pmalloc_data *data;
+	struct gen_pool_chunk *chunk;
+
+	if (unlikely(!pool))
+		return -EINVAL;
+
+	data = pool->data;
+
+	if (unlikely(!data))
+		return -EINVAL;
+
+	if (unlikely(data->protected == protection)) {
+		WARN_ON(1);
+		return 0;
+	}
+
+	data->protected = protection;
+	list_for_each_entry(chunk, &(pool)->chunks, next_chunk)
+		pmalloc_chunk_set_protection(pool, chunk, &protection);
+	return 0;
+}
+
+int pmalloc_protect_pool(struct gen_pool *pool)
+{
+	return pmalloc_pool_set_protection(pool, true);
+}
+
+
+static void pmalloc_chunk_free(struct gen_pool *pool,
+			       struct gen_pool_chunk *chunk, void *data)
+{
+	untag_chunk(chunk);
+	gen_pool_flush_chunk(pool, chunk);
+	vfree_atomic((void *)chunk->start_addr);
+}
+
+
+int pmalloc_destroy_pool(struct gen_pool *pool)
+{
+	struct pmalloc_data *data;
+
+	if (unlikely(pool == NULL))
+		return -EINVAL;
+
+	data = pool->data;
+
+	if (unlikely(data == NULL))
+		return -EINVAL;
+
+	mutex_lock(&pmalloc_mutex);
+	list_del(&data->node);
+	mutex_unlock(&pmalloc_mutex);
+
+	if (likely(data->pool_kobject))
+		pmalloc_disconnect(data, data->pool_kobject);
+
+	pmalloc_pool_set_protection(pool, false);
+	gen_pool_for_each_chunk(pool, pmalloc_chunk_free, NULL);
+	gen_pool_destroy(pool);
+	kfree(data);
+	return 0;
+}
+
+/*
+ * When the sysfs is ready to receive registrations, connect all the
+ * pools previously created. Also enable further pools to be connected
+ * right away.
+ */
+static int __init pmalloc_late_init(void)
+{
+	struct pmalloc_data *data, *n;
+
+	pmalloc_kobject = kobject_create_and_add("pmalloc", kernel_kobj);
+
+	mutex_lock(&pmalloc_mutex);
+	pmalloc_list = &pmalloc_final_list;
+
+	if (likely(pmalloc_kobject != NULL)) {
+		list_for_each_entry_safe(data, n, &pmalloc_tmp_list, node) {
+			list_move(&data->node, &pmalloc_final_list);
+			pmalloc_connect(data);
+		}
+	}
+	mutex_unlock(&pmalloc_mutex);
+	return 0;
+}
+late_initcall(pmalloc_late_init);