x86/mm: Fix pgd_lock deadlock

[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.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@ucw.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/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_hotplug.h>
#include <linux/nmi.h>
#include <linux/gfp.h>

#include <asm/processor.h>
#include <asm/bios_ebda.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>
#include <asm/cacheflush.h>
#include <asm/init.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 _end.  _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 end = roundup((unsigned long)_end, PMD_SIZE) - 1;
        pmd_t *pmd = level2_kernel_pgt;
        pmd_t *last_pmd = pmd + PTRS_PER_PMD;

        for (; pmd < last_pmd; 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 = e820_table_end++;
        void *adr;

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

                return adr;
        }

        if (pfn >= e820_table_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 unmap_low_page(void *adr)
{
        if (after_bootmem)
                return;

        early_iounmap(adr, 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)) {
                        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_pte_update(pmd_t *pmd, unsigned long address, unsigned long end,
                pgprot_t prot)
{
        pte_t *pte = (pte_t *)pmd_page_vaddr(*pmd);

        return phys_pte_init(pte, address, end, prot);
}

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;
        unsigned long last_map_addr = end;

        int i = pmd_index(address);

        for (; i < PTRS_PER_PMD; i++, address += PMD_SIZE) {
                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;
                }

                if (pmd_val(*pmd)) {
                        if (!pmd_large(*pmd)) {
                                spin_lock(&init_mm.page_table_lock);
                                last_map_addr = phys_pte_update(pmd, address,
                                                                end, prot);
                                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)) {
                                pages++;
                                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 = (address & PMD_MASK) + PMD_SIZE;
                        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_pmd_update(pud_t *pud, unsigned long address, unsigned long end,
                unsigned long page_size_mask, pgprot_t prot)
{
        pmd_t *pmd = pmd_offset(pud, 0);
        unsigned long last_map_addr;

        last_map_addr = phys_pmd_init(pmd, address, end, page_size_mask, prot);
        __flush_tlb_all();
        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;
        unsigned long last_map_addr = 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;
                pgprot_t prot = PAGE_KERNEL;

                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)) {
                        if (!pud_large(*pud)) {
                                last_map_addr = phys_pmd_update(pud, addr, end,
                                                         page_size_mask, prot);
                                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)) {
                                pages++;
                                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 = (addr & PUD_MASK) + PUD_SIZE;
                        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;
}

static unsigned long __meminit
phys_pud_update(pgd_t *pgd, unsigned long addr, unsigned long end,
                 unsigned long page_size_mask)
{
        pud_t *pud;

        pud = (pud_t *)pgd_page_vaddr(*pgd);

        return phys_pud_init(pud, addr, end, page_size_mask);
}

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)) {
                        last_map_addr = phys_pud_update(pgd, __pa(start),
                                                 __pa(end), page_size_mask);
                        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(unsigned long start_pfn, unsigned long end_pfn,
                                int acpi, int k8)
{
        memblock_x86_register_active_regions(0, start_pfn, end_pfn);
}
#endif

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] = max_pfn;

        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);

        free_area_init_nodes(max_zone_pfns);
}

/*
 * 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);

#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_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 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.
 */
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