+#define NR_MEM_SECTIONS (1UL << SECTIONS_SHIFT)
+
+#define PAGES_PER_SECTION (1UL << PFN_SECTION_SHIFT)
+#define PAGE_SECTION_MASK (~(PAGES_PER_SECTION-1))
+
+#if (MAX_ORDER - 1 + PAGE_SHIFT) > SECTION_SIZE_BITS
+#error Allocator MAX_ORDER exceeds SECTION_SIZE
+#endif
+
+struct page;
+struct mem_section {
+ /*
+ * This is, logically, a pointer to an array of struct
+ * pages. However, it is stored with some other magic.
+ * (see sparse.c::sparse_init_one_section())
+ *
+ * Additionally during early boot we encode node id of
+ * the location of the section here to guide allocation.
+ * (see sparse.c::memory_present())
+ *
+ * Making it a UL at least makes someone do a cast
+ * before using it wrong.
+ */
+ unsigned long section_mem_map;
+};
+
+#ifdef CONFIG_SPARSEMEM_EXTREME
+#define SECTIONS_PER_ROOT (PAGE_SIZE / sizeof (struct mem_section))
+#else
+#define SECTIONS_PER_ROOT 1
+#endif
+
+#define SECTION_NR_TO_ROOT(sec) ((sec) / SECTIONS_PER_ROOT)
+#define NR_SECTION_ROOTS (NR_MEM_SECTIONS / SECTIONS_PER_ROOT)
+#define SECTION_ROOT_MASK (SECTIONS_PER_ROOT - 1)
+
+#ifdef CONFIG_SPARSEMEM_EXTREME
+extern struct mem_section *mem_section[NR_SECTION_ROOTS];
+#else
+extern struct mem_section mem_section[NR_SECTION_ROOTS][SECTIONS_PER_ROOT];
+#endif
+
+static inline struct mem_section *__nr_to_section(unsigned long nr)
+{
+ if (!mem_section[SECTION_NR_TO_ROOT(nr)])
+ return NULL;
+ return &mem_section[SECTION_NR_TO_ROOT(nr)][nr & SECTION_ROOT_MASK];
+}
+extern int __section_nr(struct mem_section* ms);
+
+/*
+ * We use the lower bits of the mem_map pointer to store
+ * a little bit of information. There should be at least
+ * 3 bits here due to 32-bit alignment.
+ */
+#define SECTION_MARKED_PRESENT (1UL<<0)
+#define SECTION_HAS_MEM_MAP (1UL<<1)
+#define SECTION_MAP_LAST_BIT (1UL<<2)
+#define SECTION_MAP_MASK (~(SECTION_MAP_LAST_BIT-1))
+#define SECTION_NID_SHIFT 2
+
+static inline struct page *__section_mem_map_addr(struct mem_section *section)
+{
+ unsigned long map = section->section_mem_map;
+ map &= SECTION_MAP_MASK;
+ return (struct page *)map;
+}
+
+static inline int valid_section(struct mem_section *section)
+{
+ return (section && (section->section_mem_map & SECTION_MARKED_PRESENT));
+}
+
+static inline int section_has_mem_map(struct mem_section *section)
+{
+ return (section && (section->section_mem_map & SECTION_HAS_MEM_MAP));
+}
+
+static inline int valid_section_nr(unsigned long nr)
+{
+ return valid_section(__nr_to_section(nr));
+}
+
+static inline struct mem_section *__pfn_to_section(unsigned long pfn)
+{
+ return __nr_to_section(pfn_to_section_nr(pfn));
+}
+
+static inline int pfn_valid(unsigned long pfn)
+{
+ if (pfn_to_section_nr(pfn) >= NR_MEM_SECTIONS)
+ return 0;
+ return valid_section(__nr_to_section(pfn_to_section_nr(pfn)));
+}
+
+/*
+ * These are _only_ used during initialisation, therefore they
+ * can use __initdata ... They could have names to indicate
+ * this restriction.
+ */
+#ifdef CONFIG_NUMA
+#define pfn_to_nid(pfn) \
+({ \
+ unsigned long __pfn_to_nid_pfn = (pfn); \
+ page_to_nid(pfn_to_page(__pfn_to_nid_pfn)); \
+})
+#else
+#define pfn_to_nid(pfn) (0)
+#endif
+
+#define early_pfn_valid(pfn) pfn_valid(pfn)
+void sparse_init(void);
+#else
+#define sparse_init() do {} while (0)
+#define sparse_index_init(_sec, _nid) do {} while (0)
+#endif /* CONFIG_SPARSEMEM */
+
+#ifdef CONFIG_NODES_SPAN_OTHER_NODES
+#define early_pfn_in_nid(pfn, nid) (early_pfn_to_nid(pfn) == (nid))
+#else
+#define early_pfn_in_nid(pfn, nid) (1)
+#endif
+
+#ifndef early_pfn_valid
+#define early_pfn_valid(pfn) (1)
+#endif
+
+void memory_present(int nid, unsigned long start, unsigned long end);
+unsigned long __init node_memmap_size_bytes(int, unsigned long, unsigned long);
+
+/*
+ * If it is possible to have holes within a MAX_ORDER_NR_PAGES, then we
+ * need to check pfn validility within that MAX_ORDER_NR_PAGES block.
+ * pfn_valid_within() should be used in this case; we optimise this away
+ * when we have no holes within a MAX_ORDER_NR_PAGES block.
+ */
+#ifdef CONFIG_HOLES_IN_ZONE
+#define pfn_valid_within(pfn) pfn_valid(pfn)
+#else
+#define pfn_valid_within(pfn) (1)