* information is stored (in the form of a block of bitmap)
* It also contains the pfns that correspond to the start and end of
* the represented memory area.
+ *
+ * The memory bitmap is organized as a radix tree to guarantee fast random
+ * access to the bits. There is one radix tree for each zone (as returned
+ * from create_mem_extents).
+ *
+ * One radix tree is represented by one struct mem_zone_bm_rtree. There are
+ * two linked lists for the nodes of the tree, one for the inner nodes and
+ * one for the leave nodes. The linked leave nodes are used for fast linear
+ * access of the memory bitmap.
+ *
+ * The struct rtree_node represents one node of the radix tree.
*/
#define BM_END_OF_MAP (~0UL)
#define BM_BITS_PER_BLOCK (PAGE_SIZE * BITS_PER_BYTE)
+#define BM_BLOCK_SHIFT (PAGE_SHIFT + 3)
+#define BM_BLOCK_MASK ((1UL << BM_BLOCK_SHIFT) - 1)
struct bm_block {
struct list_head hook; /* hook into a list of bitmap blocks */
return bb->end_pfn - bb->start_pfn;
}
+/*
+ * struct rtree_node is a wrapper struct to link the nodes
+ * of the rtree together for easy linear iteration over
+ * bits and easy freeing
+ */
+struct rtree_node {
+ struct list_head list;
+ unsigned long *data;
+};
+
+/*
+ * struct mem_zone_bm_rtree represents a bitmap used for one
+ * populated memory zone.
+ */
+struct mem_zone_bm_rtree {
+ struct list_head list; /* Link Zones together */
+ struct list_head nodes; /* Radix Tree inner nodes */
+ struct list_head leaves; /* Radix Tree leaves */
+ unsigned long start_pfn; /* Zone start page frame */
+ unsigned long end_pfn; /* Zone end page frame + 1 */
+ struct rtree_node *rtree; /* Radix Tree Root */
+ int levels; /* Number of Radix Tree Levels */
+ unsigned int blocks; /* Number of Bitmap Blocks */
+};
+
/* strcut bm_position is used for browsing memory bitmaps */
struct bm_position {
};
struct memory_bitmap {
+ struct list_head zones;
struct list_head blocks; /* list of bitmap blocks */
struct linked_page *p_list; /* list of pages used to store zone
* bitmap objects and bitmap block
/* Functions that operate on memory bitmaps */
+#define BM_ENTRIES_PER_LEVEL (PAGE_SIZE / sizeof(unsigned long))
+#if BITS_PER_LONG == 32
+#define BM_RTREE_LEVEL_SHIFT (PAGE_SHIFT - 2)
+#else
+#define BM_RTREE_LEVEL_SHIFT (PAGE_SHIFT - 3)
+#endif
+#define BM_RTREE_LEVEL_MASK ((1UL << BM_RTREE_LEVEL_SHIFT) - 1)
+
+/*
+ * alloc_rtree_node - Allocate a new node and add it to the radix tree.
+ *
+ * This function is used to allocate inner nodes as well as the
+ * leave nodes of the radix tree. It also adds the node to the
+ * corresponding linked list passed in by the *list parameter.
+ */
+static struct rtree_node *alloc_rtree_node(gfp_t gfp_mask, int safe_needed,
+ struct chain_allocator *ca,
+ struct list_head *list)
+{
+ struct rtree_node *node;
+
+ node = chain_alloc(ca, sizeof(struct rtree_node));
+ if (!node)
+ return NULL;
+
+ node->data = get_image_page(gfp_mask, safe_needed);
+ if (!node->data)
+ return NULL;
+
+ list_add_tail(&node->list, list);
+
+ return node;
+}
+
+/*
+ * add_rtree_block - Add a new leave node to the radix tree
+ *
+ * The leave nodes need to be allocated in order to keep the leaves
+ * linked list in order. This is guaranteed by the zone->blocks
+ * counter.
+ */
+static int add_rtree_block(struct mem_zone_bm_rtree *zone, gfp_t gfp_mask,
+ int safe_needed, struct chain_allocator *ca)
+{
+ struct rtree_node *node, *block, **dst;
+ unsigned int levels_needed, block_nr;
+ int i;
+
+ block_nr = zone->blocks;
+ levels_needed = 0;
+
+ /* How many levels do we need for this block nr? */
+ while (block_nr) {
+ levels_needed += 1;
+ block_nr >>= BM_RTREE_LEVEL_SHIFT;
+ }
+
+ /* Make sure the rtree has enough levels */
+ for (i = zone->levels; i < levels_needed; i++) {
+ node = alloc_rtree_node(gfp_mask, safe_needed, ca,
+ &zone->nodes);
+ if (!node)
+ return -ENOMEM;
+
+ node->data[0] = (unsigned long)zone->rtree;
+ zone->rtree = node;
+ zone->levels += 1;
+ }
+
+ /* Allocate new block */
+ block = alloc_rtree_node(gfp_mask, safe_needed, ca, &zone->leaves);
+ if (!block)
+ return -ENOMEM;
+
+ /* Now walk the rtree to insert the block */
+ node = zone->rtree;
+ dst = &zone->rtree;
+ block_nr = zone->blocks;
+ for (i = zone->levels; i > 0; i--) {
+ int index;
+
+ if (!node) {
+ node = alloc_rtree_node(gfp_mask, safe_needed, ca,
+ &zone->nodes);
+ if (!node)
+ return -ENOMEM;
+ *dst = node;
+ }
+
+ index = block_nr >> ((i - 1) * BM_RTREE_LEVEL_SHIFT);
+ index &= BM_RTREE_LEVEL_MASK;
+ dst = (struct rtree_node **)&((*dst)->data[index]);
+ node = *dst;
+ }
+
+ zone->blocks += 1;
+ *dst = block;
+
+ return 0;
+}
+
+static void free_zone_bm_rtree(struct mem_zone_bm_rtree *zone,
+ int clear_nosave_free);
+
+/*
+ * create_zone_bm_rtree - create a radix tree for one zone
+ *
+ * Allocated the mem_zone_bm_rtree structure and initializes it.
+ * This function also allocated and builds the radix tree for the
+ * zone.
+ */
+static struct mem_zone_bm_rtree *
+create_zone_bm_rtree(gfp_t gfp_mask, int safe_needed,
+ struct chain_allocator *ca,
+ unsigned long start, unsigned long end)
+{
+ struct mem_zone_bm_rtree *zone;
+ unsigned int i, nr_blocks;
+ unsigned long pages;
+
+ pages = end - start;
+ zone = chain_alloc(ca, sizeof(struct mem_zone_bm_rtree));
+ if (!zone)
+ return NULL;
+
+ INIT_LIST_HEAD(&zone->nodes);
+ INIT_LIST_HEAD(&zone->leaves);
+ zone->start_pfn = start;
+ zone->end_pfn = end;
+ nr_blocks = DIV_ROUND_UP(pages, BM_BITS_PER_BLOCK);
+
+ for (i = 0; i < nr_blocks; i++) {
+ if (add_rtree_block(zone, gfp_mask, safe_needed, ca)) {
+ free_zone_bm_rtree(zone, PG_UNSAFE_CLEAR);
+ return NULL;
+ }
+ }
+
+ return zone;
+}
+
+/*
+ * free_zone_bm_rtree - Free the memory of the radix tree
+ *
+ * Free all node pages of the radix tree. The mem_zone_bm_rtree
+ * structure itself is not freed here nor are the rtree_node
+ * structs.
+ */
+static void free_zone_bm_rtree(struct mem_zone_bm_rtree *zone,
+ int clear_nosave_free)
+{
+ struct rtree_node *node;
+
+ list_for_each_entry(node, &zone->nodes, list)
+ free_image_page(node->data, clear_nosave_free);
+
+ list_for_each_entry(node, &zone->leaves, list)
+ free_image_page(node->data, clear_nosave_free);
+}
+
static void memory_bm_position_reset(struct memory_bitmap *bm)
{
bm->cur.block = list_entry(bm->blocks.next, struct bm_block, hook);
chain_init(&ca, gfp_mask, safe_needed);
INIT_LIST_HEAD(&bm->blocks);
+ INIT_LIST_HEAD(&bm->zones);
error = create_mem_extents(&mem_extents, gfp_mask);
if (error)
return error;
list_for_each_entry(ext, &mem_extents, hook) {
+ struct mem_zone_bm_rtree *zone;
struct bm_block *bb;
unsigned long pfn = ext->start;
unsigned long pages = ext->end - ext->start;
}
bb->end_pfn = pfn;
}
+
+ zone = create_zone_bm_rtree(gfp_mask, safe_needed, &ca,
+ ext->start, ext->end);
+ if (!zone)
+ goto Error;
+ list_add_tail(&zone->list, &bm->zones);
}
bm->p_list = ca.chain;
*/
static void memory_bm_free(struct memory_bitmap *bm, int clear_nosave_free)
{
+ struct mem_zone_bm_rtree *zone;
struct bm_block *bb;
list_for_each_entry(bb, &bm->blocks, hook)
if (bb->data)
free_image_page(bb->data, clear_nosave_free);
+ list_for_each_entry(zone, &bm->zones, list)
+ free_zone_bm_rtree(zone, clear_nosave_free);
+
free_list_of_pages(bm->p_list, clear_nosave_free);
+ INIT_LIST_HEAD(&bm->zones);
INIT_LIST_HEAD(&bm->blocks);
}
unsigned int snapshot_additional_pages(struct zone *zone)
{
+ unsigned int rtree, nodes;
unsigned int res;
res = DIV_ROUND_UP(zone->spanned_pages, BM_BITS_PER_BLOCK);
res += DIV_ROUND_UP(res * sizeof(struct bm_block),
LINKED_PAGE_DATA_SIZE);
- return 2 * res;
+ rtree = nodes = DIV_ROUND_UP(zone->spanned_pages, BM_BITS_PER_BLOCK);
+ rtree += DIV_ROUND_UP(rtree * sizeof(struct rtree_node),
+ LINKED_PAGE_DATA_SIZE);
+ while (nodes > 1) {
+ nodes = DIV_ROUND_UP(nodes, BM_ENTRIES_PER_LEVEL);
+ rtree += nodes;
+ }
+
+ return 2 * (res + rtree);
}
#ifdef CONFIG_HIGHMEM
projects / GitHub / LineageOS / android_kernel_motorola_exynos9610.git / commitdiff