Merge branch 'task_killable' of git://git.kernel.org/pub/scm/linux/kernel/git/willy...

[deliverable/linux.git] / arch / x86 / mm / init_64.c

/*
 *  linux/arch/x86_64/mm/init.c
 *
 *  Copyright (C) 1995  Linus Torvalds
 *  Copyright (C) 2000  Pavel Machek <pavel@suse.cz>
 *  Copyright (C) 2002,2003 Andi Kleen <ak@suse.de>
 */

#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/ptrace.h>
#include <linux/mman.h>
#include <linux/mm.h>
#include <linux/swap.h>
#include <linux/smp.h>
#include <linux/init.h>
#include <linux/pagemap.h>
#include <linux/bootmem.h>
#include <linux/proc_fs.h>
#include <linux/pci.h>
#include <linux/pfn.h>
#include <linux/poison.h>
#include <linux/dma-mapping.h>
#include <linux/module.h>
#include <linux/memory_hotplug.h>
#include <linux/nmi.h>

#include <asm/processor.h>
#include <asm/system.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/pgalloc.h>
#include <asm/dma.h>
#include <asm/fixmap.h>
#include <asm/e820.h>
#include <asm/apic.h>
#include <asm/tlb.h>
#include <asm/mmu_context.h>
#include <asm/proto.h>
#include <asm/smp.h>
#include <asm/sections.h>
#include <asm/kdebug.h>
#include <asm/numa.h>

const struct dma_mapping_ops *dma_ops;
EXPORT_SYMBOL(dma_ops);

static unsigned long dma_reserve __initdata;

DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);

/*
 * NOTE: pagetable_init alloc all the fixmap pagetables contiguous on the
 * physical space so we can cache the place of the first one and move
 * around without checking the pgd every time.
 */

void show_mem(void)
{
        long i, total = 0, reserved = 0;
        long shared = 0, cached = 0;
        struct page *page;
        pg_data_t *pgdat;

        printk(KERN_INFO "Mem-info:\n");
        show_free_areas();
        printk(KERN_INFO "Free swap:       %6ldkB\n",
                nr_swap_pages << (PAGE_SHIFT-10));

        for_each_online_pgdat(pgdat) {
                for (i = 0; i < pgdat->node_spanned_pages; ++i) {
                        /*
                         * This loop can take a while with 256 GB and
                         * 4k pages so defer the NMI watchdog:
                         */
                        if (unlikely(i % MAX_ORDER_NR_PAGES == 0))
                                touch_nmi_watchdog();

                        if (!pfn_valid(pgdat->node_start_pfn + i))
                                continue;

                        page = pfn_to_page(pgdat->node_start_pfn + i);
                        total++;
                        if (PageReserved(page))
                                reserved++;
                        else if (PageSwapCache(page))
                                cached++;
                        else if (page_count(page))
                                shared += page_count(page) - 1;
                }
        }
        printk(KERN_INFO "%lu pages of RAM\n",          total);
        printk(KERN_INFO "%lu reserved pages\n",        reserved);
        printk(KERN_INFO "%lu pages shared\n",          shared);
        printk(KERN_INFO "%lu pages swap cached\n",     cached);
}

int after_bootmem;

static __init void *spp_getpage(void)
{
        void *ptr;

        if (after_bootmem)
                ptr = (void *) get_zeroed_page(GFP_ATOMIC);
        else
                ptr = alloc_bootmem_pages(PAGE_SIZE);

        if (!ptr || ((unsigned long)ptr & ~PAGE_MASK)) {
                panic("set_pte_phys: cannot allocate page data %s\n",
                        after_bootmem ? "after bootmem" : "");
        }

        pr_debug("spp_getpage %p\n", ptr);

        return ptr;
}

static __init void
set_pte_phys(unsigned long vaddr, unsigned long phys, pgprot_t prot)
{
        pgd_t *pgd;
        pud_t *pud;
        pmd_t *pmd;
        pte_t *pte, new_pte;

        pr_debug("set_pte_phys %lx to %lx\n", vaddr, phys);

        pgd = pgd_offset_k(vaddr);
        if (pgd_none(*pgd)) {
                printk(KERN_ERR
                        "PGD FIXMAP MISSING, it should be setup in head.S!\n");
                return;
        }
        pud = pud_offset(pgd, vaddr);
        if (pud_none(*pud)) {
                pmd = (pmd_t *) spp_getpage();
                set_pud(pud, __pud(__pa(pmd) | _KERNPG_TABLE | _PAGE_USER));
                if (pmd != pmd_offset(pud, 0)) {
                        printk(KERN_ERR "PAGETABLE BUG #01! %p <-> %p\n",
                                pmd, pmd_offset(pud, 0));
                        return;
                }
        }
        pmd = pmd_offset(pud, vaddr);
        if (pmd_none(*pmd)) {
                pte = (pte_t *) spp_getpage();
                set_pmd(pmd, __pmd(__pa(pte) | _KERNPG_TABLE | _PAGE_USER));
                if (pte != pte_offset_kernel(pmd, 0)) {
                        printk(KERN_ERR "PAGETABLE BUG #02!\n");
                        return;
                }
        }
        new_pte = pfn_pte(phys >> PAGE_SHIFT, prot);

        pte = pte_offset_kernel(pmd, vaddr);
        if (!pte_none(*pte) &&
            pte_val(*pte) != (pte_val(new_pte) & __supported_pte_mask))
                pte_ERROR(*pte);
        set_pte(pte, new_pte);

        /*
         * It's enough to flush this one mapping.
         * (PGE mappings get flushed as well)
         */
        __flush_tlb_one(vaddr);
}

/* NOTE: this is meant to be run only at boot */
void __init
__set_fixmap(enum fixed_addresses idx, unsigned long phys, pgprot_t prot)
{
        unsigned long address = __fix_to_virt(idx);

        if (idx >= __end_of_fixed_addresses) {
                printk(KERN_ERR "Invalid __set_fixmap\n");
                return;
        }
        set_pte_phys(address, phys, prot);
}

static unsigned long __initdata table_start;
static unsigned long __meminitdata table_end;

static __meminit void *alloc_low_page(unsigned long *phys)
{
        unsigned long pfn = table_end++;
        void *adr;

        if (after_bootmem) {
                adr = (void *)get_zeroed_page(GFP_ATOMIC);
                *phys = __pa(adr);

                return adr;
        }

        if (pfn >= end_pfn)
                panic("alloc_low_page: ran out of memory");

        adr = early_ioremap(pfn * PAGE_SIZE, PAGE_SIZE);
        memset(adr, 0, PAGE_SIZE);
        *phys  = pfn * PAGE_SIZE;
        return adr;
}

static __meminit void unmap_low_page(void *adr)
{
        if (after_bootmem)
                return;

        early_iounmap(adr, PAGE_SIZE);
}

/* Must run before zap_low_mappings */
__meminit void *early_ioremap(unsigned long addr, unsigned long size)
{
        pmd_t *pmd, *last_pmd;
        unsigned long vaddr;
        int i, pmds;

        pmds = ((addr & ~PMD_MASK) + size + ~PMD_MASK) / PMD_SIZE;
        vaddr = __START_KERNEL_map;
        pmd = level2_kernel_pgt;
        last_pmd = level2_kernel_pgt + PTRS_PER_PMD - 1;

        for (; pmd <= last_pmd; pmd++, vaddr += PMD_SIZE) {
                for (i = 0; i < pmds; i++) {
                        if (pmd_present(pmd[i]))
                                goto continue_outer_loop;
                }
                vaddr += addr & ~PMD_MASK;
                addr &= PMD_MASK;

                for (i = 0; i < pmds; i++, addr += PMD_SIZE)
                        set_pmd(pmd+i, __pmd(addr | __PAGE_KERNEL_LARGE_EXEC));
                __flush_tlb_all();

                return (void *)vaddr;
continue_outer_loop:
                ;
        }
        printk(KERN_ERR "early_ioremap(0x%lx, %lu) failed\n", addr, size);

        return NULL;
}

/*
 * To avoid virtual aliases later:
 */
__meminit void early_iounmap(void *addr, unsigned long size)
{
        unsigned long vaddr;
        pmd_t *pmd;
        int i, pmds;

        vaddr = (unsigned long)addr;
        pmds = ((vaddr & ~PMD_MASK) + size + ~PMD_MASK) / PMD_SIZE;
        pmd = level2_kernel_pgt + pmd_index(vaddr);

        for (i = 0; i < pmds; i++)
                pmd_clear(pmd + i);

        __flush_tlb_all();
}

static void __meminit
phys_pmd_init(pmd_t *pmd_page, unsigned long address, unsigned long end)
{
        int i = pmd_index(address);

        for (; i < PTRS_PER_PMD; i++, address += PMD_SIZE) {
                unsigned long entry;
                pmd_t *pmd = pmd_page + pmd_index(address);

                if (address >= end) {
                        if (!after_bootmem) {
                                for (; i < PTRS_PER_PMD; i++, pmd++)
                                        set_pmd(pmd, __pmd(0));
                        }
                        break;
                }

                if (pmd_val(*pmd))
                        continue;

                entry = __PAGE_KERNEL_LARGE|_PAGE_GLOBAL|address;
                entry &= __supported_pte_mask;
                set_pmd(pmd, __pmd(entry));
        }
}

static void __meminit
phys_pmd_update(pud_t *pud, unsigned long address, unsigned long end)
{
        pmd_t *pmd = pmd_offset(pud, 0);
        spin_lock(&init_mm.page_table_lock);
        phys_pmd_init(pmd, address, end);
        spin_unlock(&init_mm.page_table_lock);
        __flush_tlb_all();
}

static void __meminit
phys_pud_init(pud_t *pud_page, unsigned long addr, unsigned long end)
{
        int i = pud_index(addr);

        for (; i < PTRS_PER_PUD; i++, addr = (addr & PUD_MASK) + PUD_SIZE) {
                unsigned long pmd_phys;
                pud_t *pud = pud_page + pud_index(addr);
                pmd_t *pmd;

                if (addr >= end)
                        break;

                if (!after_bootmem &&
                                !e820_any_mapped(addr, addr+PUD_SIZE, 0)) {
                        set_pud(pud, __pud(0));
                        continue;
                }

                if (pud_val(*pud)) {
                        phys_pmd_update(pud, addr, end);
                        continue;
                }

                pmd = alloc_low_page(&pmd_phys);

                spin_lock(&init_mm.page_table_lock);
                set_pud(pud, __pud(pmd_phys | _KERNPG_TABLE));
                phys_pmd_init(pmd, addr, end);
                spin_unlock(&init_mm.page_table_lock);

                unmap_low_page(pmd);
        }
        __flush_tlb_all();
}

static void __init find_early_table_space(unsigned long end)
{
        unsigned long puds, pmds, tables, start;

        puds = (end + PUD_SIZE - 1) >> PUD_SHIFT;
        pmds = (end + PMD_SIZE - 1) >> PMD_SHIFT;
        tables = round_up(puds * sizeof(pud_t), PAGE_SIZE) +
                 round_up(pmds * sizeof(pmd_t), PAGE_SIZE);

        /*
         * RED-PEN putting page tables only on node 0 could
         * cause a hotspot and fill up ZONE_DMA. The page tables
         * need roughly 0.5KB per GB.
         */
        start = 0x8000;
        table_start = find_e820_area(start, end, tables);
        if (table_start == -1UL)
                panic("Cannot find space for the kernel page tables");

        /*
         * When you have a lot of RAM like 256GB, early_table will not fit
         * into 0x8000 range, find_e820_area() will find area after kernel
         * bss but the table_start is not page aligned, so need to round it
         * up to avoid overlap with bss:
         */
        table_start = round_up(table_start, PAGE_SIZE);
        table_start >>= PAGE_SHIFT;
        table_end = table_start;

        early_printk("kernel direct mapping tables up to %lx @ %lx-%lx\n",
                end, table_start << PAGE_SHIFT,
                (table_start << PAGE_SHIFT) + tables);
}

/*
 * Setup the direct mapping of the physical memory at PAGE_OFFSET.
 * This runs before bootmem is initialized and gets pages directly from
 * the physical memory. To access them they are temporarily mapped.
 */
void __init_refok init_memory_mapping(unsigned long start, unsigned long end)
{
        unsigned long next;

        pr_debug("init_memory_mapping\n");

        /*
         * Find space for the kernel direct mapping tables.
         *
         * Later we should allocate these tables in the local node of the
         * memory mapped. Unfortunately this is done currently before the
         * nodes are discovered.
         */
        if (!after_bootmem)
                find_early_table_space(end);

        start = (unsigned long)__va(start);
        end = (unsigned long)__va(end);

        for (; start < end; start = next) {
                pgd_t *pgd = pgd_offset_k(start);
                unsigned long pud_phys;
                pud_t *pud;

                if (after_bootmem)
                        pud = pud_offset(pgd, start & PGDIR_MASK);
                else
                        pud = alloc_low_page(&pud_phys);

                next = start + PGDIR_SIZE;
                if (next > end)
                        next = end;
                phys_pud_init(pud, __pa(start), __pa(next));
                if (!after_bootmem)
                        set_pgd(pgd_offset_k(start), mk_kernel_pgd(pud_phys));
                unmap_low_page(pud);
        }

        if (!after_bootmem)
                mmu_cr4_features = read_cr4();
        __flush_tlb_all();

        reserve_early(table_start << PAGE_SHIFT, table_end << PAGE_SHIFT);
}

#ifndef CONFIG_NUMA
void __init paging_init(void)
{
        unsigned long max_zone_pfns[MAX_NR_ZONES];

        memset(max_zone_pfns, 0, sizeof(max_zone_pfns));
        max_zone_pfns[ZONE_DMA] = MAX_DMA_PFN;
        max_zone_pfns[ZONE_DMA32] = MAX_DMA32_PFN;
        max_zone_pfns[ZONE_NORMAL] = end_pfn;

        memory_present(0, 0, end_pfn);
        sparse_init();
        free_area_init_nodes(max_zone_pfns);
}
#endif

/*
 * Unmap a kernel mapping if it exists. This is useful to avoid
 * prefetches from the CPU leading to inconsistent cache lines.
 * address and size must be aligned to 2MB boundaries.
 * Does nothing when the mapping doesn't exist.
 */
void __init clear_kernel_mapping(unsigned long address, unsigned long size)
{
        unsigned long end = address + size;

        BUG_ON(address & ~LARGE_PAGE_MASK);
        BUG_ON(size & ~LARGE_PAGE_MASK);

        for (; address < end; address += LARGE_PAGE_SIZE) {
                pgd_t *pgd = pgd_offset_k(address);
                pud_t *pud;
                pmd_t *pmd;

                if (pgd_none(*pgd))
                        continue;

                pud = pud_offset(pgd, address);
                if (pud_none(*pud))
                        continue;

                pmd = pmd_offset(pud, address);
                if (!pmd || pmd_none(*pmd))
                        continue;

                if (!(pmd_val(*pmd) & _PAGE_PSE)) {
                        /*
                         * Could handle this, but it should not happen
                         * currently:
                         */
                        printk(KERN_ERR "clear_kernel_mapping: "
                                "mapping has been split. will leak memory\n");
                        pmd_ERROR(*pmd);
                }
                set_pmd(pmd, __pmd(0));
        }
        __flush_tlb_all();
}

/*
 * Memory hotplug specific functions
 */
void online_page(struct page *page)
{
        ClearPageReserved(page);
        init_page_count(page);
        __free_page(page);
        totalram_pages++;
        num_physpages++;
}

#ifdef CONFIG_MEMORY_HOTPLUG
/*
 * Memory is added always to NORMAL zone. This means you will never get
 * additional DMA/DMA32 memory.
 */
int arch_add_memory(int nid, u64 start, u64 size)
{
        struct pglist_data *pgdat = NODE_DATA(nid);
        struct zone *zone = pgdat->node_zones + ZONE_NORMAL;
        unsigned long start_pfn = start >> PAGE_SHIFT;
        unsigned long nr_pages = size >> PAGE_SHIFT;
        int ret;

        init_memory_mapping(start, start + size-1);

        ret = __add_pages(zone, start_pfn, nr_pages);
        WARN_ON(1);

        return ret;
}
EXPORT_SYMBOL_GPL(arch_add_memory);

#if !defined(CONFIG_ACPI_NUMA) && defined(CONFIG_NUMA)
int memory_add_physaddr_to_nid(u64 start)
{
        return 0;
}
EXPORT_SYMBOL_GPL(memory_add_physaddr_to_nid);
#endif

#endif /* CONFIG_MEMORY_HOTPLUG */

static struct kcore_list kcore_mem, kcore_vmalloc, kcore_kernel,
                         kcore_modules, kcore_vsyscall;

void __init mem_init(void)
{
        long codesize, reservedpages, datasize, initsize;

        pci_iommu_alloc();

        /* clear_bss() already clear the empty_zero_page */

        /* temporary debugging - double check it's true: */
        {
                int i;

                for (i = 0; i < 1024; i++)
                        WARN_ON_ONCE(empty_zero_page[i]);
        }

        reservedpages = 0;

        /* this will put all low memory onto the freelists */
#ifdef CONFIG_NUMA
        totalram_pages = numa_free_all_bootmem();
#else
        totalram_pages = free_all_bootmem();
#endif
        reservedpages = end_pfn - totalram_pages -
                                        absent_pages_in_range(0, end_pfn);
        after_bootmem = 1;

        codesize =  (unsigned long) &_etext - (unsigned long) &_text;
        datasize =  (unsigned long) &_edata - (unsigned long) &_etext;
        initsize =  (unsigned long) &__init_end - (unsigned long) &__init_begin;

        /* Register memory areas for /proc/kcore */
        kclist_add(&kcore_mem, __va(0), max_low_pfn << PAGE_SHIFT);
        kclist_add(&kcore_vmalloc, (void *)VMALLOC_START,
                   VMALLOC_END-VMALLOC_START);
        kclist_add(&kcore_kernel, &_stext, _end - _stext);
        kclist_add(&kcore_modules, (void *)MODULES_VADDR, MODULES_LEN);
        kclist_add(&kcore_vsyscall, (void *)VSYSCALL_START,
                                 VSYSCALL_END - VSYSCALL_START);

        printk(KERN_INFO "Memory: %luk/%luk available (%ldk kernel code, "
                                "%ldk reserved, %ldk data, %ldk init)\n",
                (unsigned long) nr_free_pages() << (PAGE_SHIFT-10),
                end_pfn << (PAGE_SHIFT-10),
                codesize >> 10,
                reservedpages << (PAGE_SHIFT-10),
                datasize >> 10,
                initsize >> 10);
}

void free_init_pages(char *what, unsigned long begin, unsigned long end)
{
        unsigned long addr;

        if (begin >= end)
                return;

        /*
         * If debugging page accesses then do not free this memory but
         * mark them not present - any buggy init-section access will
         * create a kernel page fault:
         */
#ifdef CONFIG_DEBUG_PAGEALLOC
        printk(KERN_INFO "debug: unmapping init memory %08lx..%08lx\n",
                begin, PAGE_ALIGN(end));
        set_memory_np(begin, (end - begin) >> PAGE_SHIFT);
#else
        printk(KERN_INFO "Freeing %s: %luk freed\n", what, (end - begin) >> 10);

        for (addr = begin; addr < end; addr += PAGE_SIZE) {
                ClearPageReserved(virt_to_page(addr));
                init_page_count(virt_to_page(addr));
                memset((void *)(addr & ~(PAGE_SIZE-1)),
                        POISON_FREE_INITMEM, PAGE_SIZE);
                free_page(addr);
                totalram_pages++;
        }
#endif
}

void free_initmem(void)
{
        free_init_pages("unused kernel memory",
                        (unsigned long)(&__init_begin),
                        (unsigned long)(&__init_end));
}

#ifdef CONFIG_DEBUG_RODATA
const int rodata_test_data = 0xC3;
EXPORT_SYMBOL_GPL(rodata_test_data);

void mark_rodata_ro(void)
{
        unsigned long start = (unsigned long)_stext, end;

#ifdef CONFIG_HOTPLUG_CPU
        /* It must still be possible to apply SMP alternatives. */
        if (num_possible_cpus() > 1)
                start = (unsigned long)_etext;
#endif

#ifdef CONFIG_KPROBES
        start = (unsigned long)__start_rodata;
#endif

        end = (unsigned long)__end_rodata;
        start = (start + PAGE_SIZE - 1) & PAGE_MASK;
        end &= PAGE_MASK;
        if (end <= start)
                return;

        set_memory_ro(start, (end - start) >> PAGE_SHIFT);

        printk(KERN_INFO "Write protecting the kernel read-only data: %luk\n",
               (end - start) >> 10);

        rodata_test();

#ifdef CONFIG_CPA_DEBUG
        printk(KERN_INFO "Testing CPA: undo %lx-%lx\n", start, end);
        set_memory_rw(start, (end-start) >> PAGE_SHIFT);

        printk(KERN_INFO "Testing CPA: again\n");
        set_memory_ro(start, (end-start) >> PAGE_SHIFT);
#endif
}
#endif

#ifdef CONFIG_BLK_DEV_INITRD
void free_initrd_mem(unsigned long start, unsigned long end)
{
        free_init_pages("initrd memory", start, end);
}
#endif

void __init reserve_bootmem_generic(unsigned long phys, unsigned len)
{
#ifdef CONFIG_NUMA
        int nid = phys_to_nid(phys);
#endif
        unsigned long pfn = phys >> PAGE_SHIFT;

        if (pfn >= end_pfn) {
                /*
                 * This can happen with kdump kernels when accessing
                 * firmware tables:
                 */
                if (pfn < end_pfn_map)
                        return;

                printk(KERN_ERR "reserve_bootmem: illegal reserve %lx %u\n",
                                phys, len);
                return;
        }

        /* Should check here against the e820 map to avoid double free */
#ifdef CONFIG_NUMA
        reserve_bootmem_node(NODE_DATA(nid), phys, len);
#else
        reserve_bootmem(phys, len);
#endif
        if (phys+len <= MAX_DMA_PFN*PAGE_SIZE) {
                dma_reserve += len / PAGE_SIZE;
                set_dma_reserve(dma_reserve);
        }
}

int kern_addr_valid(unsigned long addr)
{
        unsigned long above = ((long)addr) >> __VIRTUAL_MASK_SHIFT;
        pgd_t *pgd;
        pud_t *pud;
        pmd_t *pmd;
        pte_t *pte;

        if (above != 0 && above != -1UL)
                return 0;

        pgd = pgd_offset_k(addr);
        if (pgd_none(*pgd))
                return 0;

        pud = pud_offset(pgd, addr);
        if (pud_none(*pud))
                return 0;

        pmd = pmd_offset(pud, addr);
        if (pmd_none(*pmd))
                return 0;

        if (pmd_large(*pmd))
                return pfn_valid(pmd_pfn(*pmd));

        pte = pte_offset_kernel(pmd, addr);
        if (pte_none(*pte))
                return 0;

        return pfn_valid(pte_pfn(*pte));
}

/*
 * A pseudo VMA to allow ptrace access for the vsyscall page.  This only
 * covers the 64bit vsyscall page now. 32bit has a real VMA now and does
 * not need special handling anymore:
 */
static struct vm_area_struct gate_vma = {
        .vm_start       = VSYSCALL_START,
        .vm_end         = VSYSCALL_START + (VSYSCALL_MAPPED_PAGES * PAGE_SIZE),
        .vm_page_prot   = PAGE_READONLY_EXEC,
        .vm_flags       = VM_READ | VM_EXEC
};

struct vm_area_struct *get_gate_vma(struct task_struct *tsk)
{
#ifdef CONFIG_IA32_EMULATION
        if (test_tsk_thread_flag(tsk, TIF_IA32))
                return NULL;
#endif
        return &gate_vma;
}

int in_gate_area(struct task_struct *task, unsigned long addr)
{
        struct vm_area_struct *vma = get_gate_vma(task);

        if (!vma)
                return 0;

        return (addr >= vma->vm_start) && (addr < vma->vm_end);
}

/*
 * Use this when you have no reliable task/vma, typically from interrupt
 * context. It is less reliable than using the task's vma and may give
 * false positives:
 */
int in_gate_area_no_task(unsigned long addr)
{
        return (addr >= VSYSCALL_START) && (addr < VSYSCALL_END);
}

const char *arch_vma_name(struct vm_area_struct *vma)
{
        if (vma->vm_mm && vma->vm_start == (long)vma->vm_mm->context.vdso)
                return "[vdso]";
        if (vma == &gate_vma)
                return "[vsyscall]";
        return NULL;
}

#ifdef CONFIG_SPARSEMEM_VMEMMAP
/*
 * Initialise the sparsemem vmemmap using huge-pages at the PMD level.
 */
int __meminit
vmemmap_populate(struct page *start_page, unsigned long size, int node)
{
        unsigned long addr = (unsigned long)start_page;
        unsigned long end = (unsigned long)(start_page + size);
        unsigned long next;
        pgd_t *pgd;
        pud_t *pud;
        pmd_t *pmd;

        for (; addr < end; addr = next) {
                next = pmd_addr_end(addr, end);

                pgd = vmemmap_pgd_populate(addr, node);
                if (!pgd)
                        return -ENOMEM;

                pud = vmemmap_pud_populate(pgd, addr, node);
                if (!pud)
                        return -ENOMEM;

                pmd = pmd_offset(pud, addr);
                if (pmd_none(*pmd)) {
                        pte_t entry;
                        void *p;

                        p = vmemmap_alloc_block(PMD_SIZE, node);
                        if (!p)
                                return -ENOMEM;

                        entry = pfn_pte(__pa(p) >> PAGE_SHIFT,
                                                        PAGE_KERNEL_LARGE);
                        set_pmd(pmd, __pmd(pte_val(entry)));

                        printk(KERN_DEBUG " [%lx-%lx] PMD ->%p on node %d\n",
                                addr, addr + PMD_SIZE - 1, p, node);
                } else {
                        vmemmap_verify((pte_t *)pmd, node, addr, next);
                }
        }
        return 0;
}
#endif