+/*
+ * Subtle, we encode the real pfn into the mem_map such that
+ * the identity pfn - section_mem_map will return the actual
+ * physical page frame number.
+ */
+static unsigned long sparse_encode_mem_map(struct page *mem_map, unsigned long pnum)
+{
+ return (unsigned long)(mem_map - (section_nr_to_pfn(pnum)));
+}
+
+/*
+ * We need this if we ever free the mem_maps. While not implemented yet,
+ * this function is included for parity with its sibling.
+ */
+static __attribute((unused))
+struct page *sparse_decode_mem_map(unsigned long coded_mem_map, unsigned long pnum)
+{
+ return ((struct page *)coded_mem_map) + section_nr_to_pfn(pnum);
+}
+
+static int sparse_init_one_section(struct mem_section *ms,
+ unsigned long pnum, struct page *mem_map)
+{
+ if (!valid_section(ms))
+ return -EINVAL;
+
+ ms->section_mem_map |= sparse_encode_mem_map(mem_map, pnum);
+
+ return 1;
+}
+
+static struct page *sparse_early_mem_map_alloc(unsigned long pnum)
+{
+ struct page *map;
+ int nid = early_pfn_to_nid(section_nr_to_pfn(pnum));
+ struct mem_section *ms = __nr_to_section(pnum);
+
+ map = alloc_remap(nid, sizeof(struct page) * PAGES_PER_SECTION);
+ if (map)
+ return map;
+
+ map = alloc_bootmem_node(NODE_DATA(nid),
+ sizeof(struct page) * PAGES_PER_SECTION);
+ if (map)
+ return map;
+
+ printk(KERN_WARNING "%s: allocation failed\n", __FUNCTION__);
+ ms->section_mem_map = 0;
+ return NULL;
+}
+
+static struct page *__kmalloc_section_memmap(unsigned long nr_pages)
+{
+ struct page *page, *ret;
+ unsigned long memmap_size = sizeof(struct page) * nr_pages;
+
+ page = alloc_pages(GFP_KERNEL, get_order(memmap_size));
+ if (page)
+ goto got_map_page;
+
+ ret = vmalloc(memmap_size);
+ if (ret)
+ goto got_map_ptr;
+
+ return NULL;
+got_map_page:
+ ret = (struct page *)pfn_to_kaddr(page_to_pfn(page));
+got_map_ptr:
+ memset(ret, 0, memmap_size);
+
+ return ret;
+}
+
+static int vaddr_in_vmalloc_area(void *addr)
+{
+ if (addr >= (void *)VMALLOC_START &&
+ addr < (void *)VMALLOC_END)
+ return 1;
+ return 0;
+}
+
+static void __kfree_section_memmap(struct page *memmap, unsigned long nr_pages)
+{
+ if (vaddr_in_vmalloc_area(memmap))
+ vfree(memmap);
+ else
+ free_pages((unsigned long)memmap,
+ get_order(sizeof(struct page) * nr_pages));
+}
+