init_64.c

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/*
 *  linux/arch/x86_64/mm/init.c
 *
 *  Copyright (C) 1995  Linus Torvalds
 *  Copyright (C) 2000  Pavel Machek <[email protected]>
 *  Copyright (C) 2002,2003 Andi Kleen <[email protected]>
 */

#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/initrd.h>
#include <linux/pagemap.h>
#include <linux/bootmem.h>
#include <linux/memblock.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.h>
#include <linux/memory_hotplug.h>
#include <linux/nmi.h>
#include <linux/gfp.h>

#include <asm/processor.h>
#include <asm/bios_ebda.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>
#include <asm/cacheflush.h>
#include <asm/init.h>
#include <asm/uv/uv.h>
#include <asm/setup.h>

static int __init parse_direct_gbpages_off(char *arg)
{
    direct_gbpages = 0;
    return 0;
}
early_param("nogbpages", parse_direct_gbpages_off);

static int __init parse_direct_gbpages_on(char *arg)
{
    direct_gbpages = 1;
    return 0;
}
early_param("gbpages", parse_direct_gbpages_on);

/*
 * 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.
 */

pteval_t __supported_pte_mask __read_mostly = ~_PAGE_IOMAP;
EXPORT_SYMBOL_GPL(__supported_pte_mask);

int force_personality32;

/*
 * noexec32=on|off
 * Control non executable heap for 32bit processes.
 * To control the stack too use noexec=off
 *
 * on   PROT_READ does not imply PROT_EXEC for 32-bit processes (default)
 * off  PROT_READ implies PROT_EXEC
 */
static int __init nonx32_setup(char *str)
{
    if (!strcmp(str, "on"))
        force_personality32 &= ~READ_IMPLIES_EXEC;
    else if (!strcmp(str, "off"))
        force_personality32 |= READ_IMPLIES_EXEC;
    return 1;
}
__setup("noexec32=", nonx32_setup);

/*
 * When memory was added/removed make sure all the processes MM have
 * suitable PGD entries in the local PGD level page.
 */
void sync_global_pgds(unsigned long start, unsigned long end)
{
    unsigned long address;

    for (address = start; address <= end; address += PGDIR_SIZE) {
        const pgd_t *pgd_ref = pgd_offset_k(address);
        struct page *page;

        if (pgd_none(*pgd_ref))
            continue;

        spin_lock(&pgd_lock);
        list_for_each_entry(page, &pgd_list, lru) {
            pgd_t *pgd;
            spinlock_t *pgt_lock;

            pgd = (pgd_t *)page_address(page) + pgd_index(address);
            /* the pgt_lock only for Xen */
            pgt_lock = &pgd_page_get_mm(page)->page_table_lock;
            spin_lock(pgt_lock);

            if (pgd_none(*pgd))
                set_pgd(pgd, *pgd_ref);
            else
                BUG_ON(pgd_page_vaddr(*pgd)
                       != pgd_page_vaddr(*pgd_ref));

            spin_unlock(pgt_lock);
        }
        spin_unlock(&pgd_lock);
    }
}

/*
 * NOTE: This function is marked __ref because it calls __init function
 * (alloc_bootmem_pages). It's safe to do it ONLY when after_bootmem == 0.
 */
static __ref void *spp_getpage(void)
{
    void *ptr;

    if (after_bootmem)
        ptr = (void *) get_zeroed_page(GFP_ATOMIC | __GFP_NOTRACK);
    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 pud_t *fill_pud(pgd_t *pgd, unsigned long vaddr)
{
    if (pgd_none(*pgd)) {
        pud_t *pud = (pud_t *)spp_getpage();
        pgd_populate(&init_mm, pgd, pud);
        if (pud != pud_offset(pgd, 0))
            printk(KERN_ERR "PAGETABLE BUG #00! %p <-> %p\n",
                   pud, pud_offset(pgd, 0));
    }
    return pud_offset(pgd, vaddr);
}

static pmd_t *fill_pmd(pud_t *pud, unsigned long vaddr)
{
    if (pud_none(*pud)) {
        pmd_t *pmd = (pmd_t *) spp_getpage();
        pud_populate(&init_mm, pud, pmd);
        if (pmd != pmd_offset(pud, 0))
            printk(KERN_ERR "PAGETABLE BUG #01! %p <-> %p\n",
                   pmd, pmd_offset(pud, 0));
    }
    return pmd_offset(pud, vaddr);
}

static pte_t *fill_pte(pmd_t *pmd, unsigned long vaddr)
{
    if (pmd_none(*pmd)) {
        pte_t *pte = (pte_t *) spp_getpage();
        pmd_populate_kernel(&init_mm, pmd, pte);
        if (pte != pte_offset_kernel(pmd, 0))
            printk(KERN_ERR "PAGETABLE BUG #02!\n");
    }
    return pte_offset_kernel(pmd, vaddr);
}

void set_pte_vaddr_pud(pud_t *pud_page, unsigned long vaddr, pte_t new_pte)
{
    pud_t *pud;
    pmd_t *pmd;
    pte_t *pte;

    pud = pud_page + pud_index(vaddr);
    pmd = fill_pmd(pud, vaddr);
    pte = fill_pte(pmd, vaddr);

    set_pte(pte, new_pte);

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

void set_pte_vaddr(unsigned long vaddr, pte_t pteval)
{
    pgd_t *pgd;
    pud_t *pud_page;

    pr_debug("set_pte_vaddr %lx to %lx\n", vaddr, native_pte_val(pteval));

    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_page = (pud_t*)pgd_page_vaddr(*pgd);
    set_pte_vaddr_pud(pud_page, vaddr, pteval);
}

pmd_t * __init populate_extra_pmd(unsigned long vaddr)
{
    pgd_t *pgd;
    pud_t *pud;

    pgd = pgd_offset_k(vaddr);
    pud = fill_pud(pgd, vaddr);
    return fill_pmd(pud, vaddr);
}

pte_t * __init populate_extra_pte(unsigned long vaddr)
{
    pmd_t *pmd;

    pmd = populate_extra_pmd(vaddr);
    return fill_pte(pmd, vaddr);
}

/*
 * Create large page table mappings for a range of physical addresses.
 */
static void __init __init_extra_mapping(unsigned long phys, unsigned long size,
                        pgprot_t prot)
{
    pgd_t *pgd;
    pud_t *pud;
    pmd_t *pmd;

    BUG_ON((phys & ~PMD_MASK) || (size & ~PMD_MASK));
    for (; size; phys += PMD_SIZE, size -= PMD_SIZE) {
        pgd = pgd_offset_k((unsigned long)__va(phys));
        if (pgd_none(*pgd)) {
            pud = (pud_t *) spp_getpage();
            set_pgd(pgd, __pgd(__pa(pud) | _KERNPG_TABLE |
                        _PAGE_USER));
        }
        pud = pud_offset(pgd, (unsigned long)__va(phys));
        if (pud_none(*pud)) {
            pmd = (pmd_t *) spp_getpage();
            set_pud(pud, __pud(__pa(pmd) | _KERNPG_TABLE |
                        _PAGE_USER));
        }
        pmd = pmd_offset(pud, phys);
        BUG_ON(!pmd_none(*pmd));
        set_pmd(pmd, __pmd(phys | pgprot_val(prot)));
    }
}

void __init init_extra_mapping_wb(unsigned long phys, unsigned long size)
{
    __init_extra_mapping(phys, size, PAGE_KERNEL_LARGE);
}

void __init init_extra_mapping_uc(unsigned long phys, unsigned long size)
{
    __init_extra_mapping(phys, size, PAGE_KERNEL_LARGE_NOCACHE);
}

/*
 * The head.S code sets up the kernel high mapping:
 *
 *   from __START_KERNEL_map to __START_KERNEL_map + size (== _end-_text)
 *
 * phys_addr holds the negative offset to the kernel, which is added
 * to the compile time generated pmds. This results in invalid pmds up
 * to the point where we hit the physaddr 0 mapping.
 *
 * We limit the mappings to the region from _text to _brk_end.  _brk_end
 * is rounded up to the 2MB boundary. This catches the invalid pmds as
 * well, as they are located before _text:
 */
void __init cleanup_highmap(void)
{
    unsigned long vaddr = __START_KERNEL_map;
    unsigned long vaddr_end = __START_KERNEL_map + (max_pfn_mapped << PAGE_SHIFT);
    unsigned long end = roundup((unsigned long)_brk_end, PMD_SIZE) - 1;
    pmd_t *pmd = level2_kernel_pgt;

    for (; vaddr + PMD_SIZE - 1 < vaddr_end; pmd++, vaddr += PMD_SIZE) {
        if (pmd_none(*pmd))
            continue;
        if (vaddr < (unsigned long) _text || vaddr > end)
            set_pmd(pmd, __pmd(0));
    }
}

static __ref void *alloc_low_page(unsigned long *phys)
{
    unsigned long pfn = pgt_buf_end++;
    void *adr;

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

        return adr;
    }

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

    adr = early_memremap(pfn * PAGE_SIZE, PAGE_SIZE);
    clear_page(adr);
    *phys  = pfn * PAGE_SIZE;
    return adr;
}

static __ref void *map_low_page(void *virt)
{
    void *adr;
    unsigned long phys, left;

    if (after_bootmem)
        return virt;

    phys = __pa(virt);
    left = phys & (PAGE_SIZE - 1);
    adr = early_memremap(phys & PAGE_MASK, PAGE_SIZE);
    adr = (void *)(((unsigned long)adr) | left);

    return adr;
}

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

    early_iounmap((void *)((unsigned long)adr & PAGE_MASK), PAGE_SIZE);
}

static unsigned long __meminit
phys_pte_init(pte_t *pte_page, unsigned long addr, unsigned long end,
          pgprot_t prot)
{
    unsigned pages = 0;
    unsigned long last_map_addr = end;
    int i;

    pte_t *pte = pte_page + pte_index(addr);

    for(i = pte_index(addr); i < PTRS_PER_PTE; i++, addr += PAGE_SIZE, pte++) {

        if (addr >= end) {
            if (!after_bootmem) {
                for(; i < PTRS_PER_PTE; i++, pte++)
                    set_pte(pte, __pte(0));
            }
            break;
        }

        /*
         * We will re-use the existing mapping.
         * Xen for example has some special requirements, like mapping
         * pagetable pages as RO. So assume someone who pre-setup
         * these mappings are more intelligent.
         */
        if (pte_val(*pte)) {
            if (!after_bootmem)
                pages++;
            continue;
        }

        if (0)
            printk("   pte=%p addr=%lx pte=%016lx\n",
                   pte, addr, pfn_pte(addr >> PAGE_SHIFT, PAGE_KERNEL).pte);
        pages++;
        set_pte(pte, pfn_pte(addr >> PAGE_SHIFT, prot));
        last_map_addr = (addr & PAGE_MASK) + PAGE_SIZE;
    }

    update_page_count(PG_LEVEL_4K, pages);

    return last_map_addr;
}

static unsigned long __meminit
phys_pmd_init(pmd_t *pmd_page, unsigned long address, unsigned long end,
          unsigned long page_size_mask, pgprot_t prot)
{
    unsigned long pages = 0, next;
    unsigned long last_map_addr = end;

    int i = pmd_index(address);

    for (; i < PTRS_PER_PMD; i++, address = next) {
        unsigned long pte_phys;
        pmd_t *pmd = pmd_page + pmd_index(address);
        pte_t *pte;
        pgprot_t new_prot = prot;

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

        next = (address & PMD_MASK) + PMD_SIZE;

        if (pmd_val(*pmd)) {
            if (!pmd_large(*pmd)) {
                spin_lock(&init_mm.page_table_lock);
                pte = map_low_page((pte_t *)pmd_page_vaddr(*pmd));
                last_map_addr = phys_pte_init(pte, address,
                                end, prot);
                unmap_low_page(pte);
                spin_unlock(&init_mm.page_table_lock);
                continue;
            }
            /*
             * If we are ok with PG_LEVEL_2M mapping, then we will
             * use the existing mapping,
             *
             * Otherwise, we will split the large page mapping but
             * use the same existing protection bits except for
             * large page, so that we don't violate Intel's TLB
             * Application note (317080) which says, while changing
             * the page sizes, new and old translations should
             * not differ with respect to page frame and
             * attributes.
             */
            if (page_size_mask & (1 << PG_LEVEL_2M)) {
                if (!after_bootmem)
                    pages++;
                last_map_addr = next;
                continue;
            }
            new_prot = pte_pgprot(pte_clrhuge(*(pte_t *)pmd));
        }

        if (page_size_mask & (1<<PG_LEVEL_2M)) {
            pages++;
            spin_lock(&init_mm.page_table_lock);
            set_pte((pte_t *)pmd,
                pfn_pte(address >> PAGE_SHIFT,
                    __pgprot(pgprot_val(prot) | _PAGE_PSE)));
            spin_unlock(&init_mm.page_table_lock);
            last_map_addr = next;
            continue;
        }

        pte = alloc_low_page(&pte_phys);
        last_map_addr = phys_pte_init(pte, address, end, new_prot);
        unmap_low_page(pte);

        spin_lock(&init_mm.page_table_lock);
        pmd_populate_kernel(&init_mm, pmd, __va(pte_phys));
        spin_unlock(&init_mm.page_table_lock);
    }
    update_page_count(PG_LEVEL_2M, pages);
    return last_map_addr;
}

static unsigned long __meminit
phys_pud_init(pud_t *pud_page, unsigned long addr, unsigned long end,
             unsigned long page_size_mask)
{
    unsigned long pages = 0, next;
    unsigned long last_map_addr = end;
    int i = pud_index(addr);

    for (; i < PTRS_PER_PUD; i++, addr = next) {
        unsigned long pmd_phys;
        pud_t *pud = pud_page + pud_index(addr);
        pmd_t *pmd;
        pgprot_t prot = PAGE_KERNEL;

        if (addr >= end)
            break;

        next = (addr & PUD_MASK) + PUD_SIZE;

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

        if (pud_val(*pud)) {
            if (!pud_large(*pud)) {
                pmd = map_low_page(pmd_offset(pud, 0));
                last_map_addr = phys_pmd_init(pmd, addr, end,
                             page_size_mask, prot);
                unmap_low_page(pmd);
                __flush_tlb_all();
                continue;
            }
            /*
             * If we are ok with PG_LEVEL_1G mapping, then we will
             * use the existing mapping.
             *
             * Otherwise, we will split the gbpage mapping but use
             * the same existing protection  bits except for large
             * page, so that we don't violate Intel's TLB
             * Application note (317080) which says, while changing
             * the page sizes, new and old translations should
             * not differ with respect to page frame and
             * attributes.
             */
            if (page_size_mask & (1 << PG_LEVEL_1G)) {
                if (!after_bootmem)
                    pages++;
                last_map_addr = next;
                continue;
            }
            prot = pte_pgprot(pte_clrhuge(*(pte_t *)pud));
        }

        if (page_size_mask & (1<<PG_LEVEL_1G)) {
            pages++;
            spin_lock(&init_mm.page_table_lock);
            set_pte((pte_t *)pud,
                pfn_pte(addr >> PAGE_SHIFT, PAGE_KERNEL_LARGE));
            spin_unlock(&init_mm.page_table_lock);
            last_map_addr = next;
            continue;
        }

        pmd = alloc_low_page(&pmd_phys);
        last_map_addr = phys_pmd_init(pmd, addr, end, page_size_mask,
                          prot);
        unmap_low_page(pmd);

        spin_lock(&init_mm.page_table_lock);
        pud_populate(&init_mm, pud, __va(pmd_phys));
        spin_unlock(&init_mm.page_table_lock);
    }
    __flush_tlb_all();

    update_page_count(PG_LEVEL_1G, pages);

    return last_map_addr;
}

unsigned long __meminit
kernel_physical_mapping_init(unsigned long start,
                 unsigned long end,
                 unsigned long page_size_mask)
{
    bool pgd_changed = false;
    unsigned long next, last_map_addr = end;
    unsigned long addr;

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

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

        next = (start + PGDIR_SIZE) & PGDIR_MASK;
        if (next > end)
            next = end;

        if (pgd_val(*pgd)) {
            pud = map_low_page((pud_t *)pgd_page_vaddr(*pgd));
            last_map_addr = phys_pud_init(pud, __pa(start),
                         __pa(end), page_size_mask);
            unmap_low_page(pud);
            continue;
        }

        pud = alloc_low_page(&pud_phys);
        last_map_addr = phys_pud_init(pud, __pa(start), __pa(next),
                         page_size_mask);
        unmap_low_page(pud);

        spin_lock(&init_mm.page_table_lock);
        pgd_populate(&init_mm, pgd, __va(pud_phys));
        spin_unlock(&init_mm.page_table_lock);
        pgd_changed = true;
    }

    if (pgd_changed)
        sync_global_pgds(addr, end);

    __flush_tlb_all();

    return last_map_addr;
}

#ifndef CONFIG_NUMA
void __init initmem_init(void)
{
    memblock_set_node(0, (phys_addr_t)ULLONG_MAX, 0);
}
#endif

void __init paging_init(void)
{
    sparse_memory_present_with_active_regions(MAX_NUMNODES);
    sparse_init();

    /*
     * clear the default setting with node 0
     * note: don't use nodes_clear here, that is really clearing when
     *   numa support is not compiled in, and later node_set_state
     *   will not set it back.
     */
    node_clear_state(0, N_NORMAL_MEMORY);

    zone_sizes_init();
}

/*
 * Memory hotplug specific functions
 */
#ifdef CONFIG_MEMORY_HOTPLUG
/*
 * After memory hotplug the variables max_pfn, max_low_pfn and high_memory need
 * updating.
 */
static void  update_end_of_memory_vars(u64 start, u64 size)
{
    unsigned long end_pfn = PFN_UP(start + size);

    if (end_pfn > max_pfn) {
        max_pfn = end_pfn;
        max_low_pfn = end_pfn;
        high_memory = (void *)__va(max_pfn * PAGE_SIZE - 1) + 1;
    }
}

/*
 * 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 last_mapped_pfn, start_pfn = start >> PAGE_SHIFT;
    unsigned long nr_pages = size >> PAGE_SHIFT;
    int ret;

    last_mapped_pfn = init_memory_mapping(start, start + size);
    if (last_mapped_pfn > max_pfn_mapped)
        max_pfn_mapped = last_mapped_pfn;

    ret = __add_pages(nid, zone, start_pfn, nr_pages);
    WARN_ON_ONCE(ret);

    /* update max_pfn, max_low_pfn and high_memory */
    update_end_of_memory_vars(start, size);

    return ret;
}
EXPORT_SYMBOL_GPL(arch_add_memory);

#endif /* CONFIG_MEMORY_HOTPLUG */

static struct kcore_list kcore_vsyscall;

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

    pci_iommu_alloc();

    /* clear_bss() already clear the empty_zero_page */

    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

    absent_pages = absent_pages_in_range(0, max_pfn);
    reservedpages = max_pfn - totalram_pages - absent_pages;
    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_vsyscall, (void *)VSYSCALL_START,
             VSYSCALL_END - VSYSCALL_START, KCORE_OTHER);

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

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

int kernel_set_to_readonly;

void set_kernel_text_rw(void)
{
    unsigned long start = PFN_ALIGN(_text);
    unsigned long end = PFN_ALIGN(__stop___ex_table);

    if (!kernel_set_to_readonly)
        return;

    pr_debug("Set kernel text: %lx - %lx for read write\n",
         start, end);

    /*
     * Make the kernel identity mapping for text RW. Kernel text
     * mapping will always be RO. Refer to the comment in
     * static_protections() in pageattr.c
     */
    set_memory_rw(start, (end - start) >> PAGE_SHIFT);
}

void set_kernel_text_ro(void)
{
    unsigned long start = PFN_ALIGN(_text);
    unsigned long end = PFN_ALIGN(__stop___ex_table);

    if (!kernel_set_to_readonly)
        return;

    pr_debug("Set kernel text: %lx - %lx for read only\n",
         start, end);

    /*
     * Set the kernel identity mapping for text RO.
     */
    set_memory_ro(start, (end - start) >> PAGE_SHIFT);
}

void mark_rodata_ro(void)
{
    unsigned long start = PFN_ALIGN(_text);
    unsigned long rodata_start =
        ((unsigned long)__start_rodata + PAGE_SIZE - 1) & PAGE_MASK;
    unsigned long end = (unsigned long) &__end_rodata_hpage_align;
    unsigned long text_end = PAGE_ALIGN((unsigned long) &__stop___ex_table);
    unsigned long rodata_end = PAGE_ALIGN((unsigned long) &__end_rodata);
    unsigned long data_start = (unsigned long) &_sdata;

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

    kernel_set_to_readonly = 1;

    /*
     * The rodata section (but not the kernel text!) should also be
     * not-executable.
     */
    set_memory_nx(rodata_start, (end - rodata_start) >> PAGE_SHIFT);

    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

    free_init_pages("unused kernel memory",
            (unsigned long) page_address(virt_to_page(text_end)),
            (unsigned long)
                 page_address(virt_to_page(rodata_start)));
    free_init_pages("unused kernel memory",
            (unsigned long) page_address(virt_to_page(rodata_end)),
            (unsigned long) page_address(virt_to_page(data_start)));
}

#endif

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 mm_struct *mm)
{
#ifdef CONFIG_IA32_EMULATION
    if (!mm || mm->context.ia32_compat)
        return NULL;
#endif
    return &gate_vma;
}

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

    if (!vma)
        return 0;

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

/*
 * Use this when you have no reliable mm, typically from interrupt
 * context. It is less reliable than using a task's mm and may give
 * false positives.
 */
int in_gate_area_no_mm(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_X86_UV
unsigned long memory_block_size_bytes(void)
{
    if (is_uv_system()) {
        printk(KERN_INFO "UV: memory block size 2GB\n");
        return 2UL * 1024 * 1024 * 1024;
    }
    return MIN_MEMORY_BLOCK_SIZE;
}
#endif

#ifdef CONFIG_SPARSEMEM_VMEMMAP
/*
 * Initialise the sparsemem vmemmap using huge-pages at the PMD level.
 */
static long __meminitdata addr_start, addr_end;
static void __meminitdata *p_start, *p_end;
static int __meminitdata node_start;

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) {
        void *p = NULL;

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

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

        if (!cpu_has_pse) {
            next = (addr + PAGE_SIZE) & PAGE_MASK;
            pmd = vmemmap_pmd_populate(pud, addr, node);

            if (!pmd)
                return -ENOMEM;

            p = vmemmap_pte_populate(pmd, addr, node);

            if (!p)
                return -ENOMEM;

            addr_end = addr + PAGE_SIZE;
            p_end = p + PAGE_SIZE;
        } else {
            next = pmd_addr_end(addr, end);

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

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

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

                /* check to see if we have contiguous blocks */
                if (p_end != p || node_start != node) {
                    if (p_start)
                        printk(KERN_DEBUG " [%lx-%lx] PMD -> [%p-%p] on node %d\n",
                               addr_start, addr_end-1, p_start, p_end-1, node_start);
                    addr_start = addr;
                    node_start = node;
                    p_start = p;
                }

                addr_end = addr + PMD_SIZE;
                p_end = p + PMD_SIZE;
            } else
                vmemmap_verify((pte_t *)pmd, node, addr, next);
        }

    }
    sync_global_pgds((unsigned long)start_page, end);
    return 0;
}

void __meminit vmemmap_populate_print_last(void)
{
    if (p_start) {
        printk(KERN_DEBUG " [%lx-%lx] PMD -> [%p-%p] on node %d\n",
            addr_start, addr_end-1, p_start, p_end-1, node_start);
        p_start = NULL;
        p_end = NULL;
        node_start = 0;
    }
}
#endif