x86: fix assumed to be contiguous leaf page tables for kmap_atomic region (take 2)

[linux-2.6/mini2440.git] / arch / x86 / mm / init_32.c

/*
 *
 *  Copyright (C) 1995  Linus Torvalds
 *
 *  Support of BIGMEM added by Gerhard Wichert, Siemens AG, July 1999
 */

#include <linux/module.h>
#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/hugetlb.h>
#include <linux/swap.h>
#include <linux/smp.h>
#include <linux/init.h>
#include <linux/highmem.h>
#include <linux/pagemap.h>
#include <linux/pci.h>
#include <linux/pfn.h>
#include <linux/poison.h>
#include <linux/bootmem.h>
#include <linux/slab.h>
#include <linux/proc_fs.h>
#include <linux/memory_hotplug.h>
#include <linux/initrd.h>
#include <linux/cpumask.h>

#include <asm/asm.h>
#include <asm/bios_ebda.h>
#include <asm/processor.h>
#include <asm/system.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/dma.h>
#include <asm/fixmap.h>
#include <asm/e820.h>
#include <asm/apic.h>
#include <asm/bugs.h>
#include <asm/tlb.h>
#include <asm/tlbflush.h>
#include <asm/pgalloc.h>
#include <asm/sections.h>
#include <asm/paravirt.h>
#include <asm/setup.h>
#include <asm/cacheflush.h>
#include <asm/smp.h>

unsigned int __VMALLOC_RESERVE = 128 << 20;

unsigned long max_low_pfn_mapped;
unsigned long max_pfn_mapped;

DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);
unsigned long highstart_pfn, highend_pfn;

static noinline int do_test_wp_bit(void);


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

static int __initdata after_init_bootmem;

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

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

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

/*
 * Creates a middle page table and puts a pointer to it in the
 * given global directory entry. This only returns the gd entry
 * in non-PAE compilation mode, since the middle layer is folded.
 */
static pmd_t * __init one_md_table_init(pgd_t *pgd)
{
        pud_t *pud;
        pmd_t *pmd_table;

#ifdef CONFIG_X86_PAE
        if (!(pgd_val(*pgd) & _PAGE_PRESENT)) {
                if (after_init_bootmem)
                        pmd_table = (pmd_t *)alloc_bootmem_low_pages(PAGE_SIZE);
                else
                        pmd_table = (pmd_t *)alloc_low_page();
                paravirt_alloc_pmd(&init_mm, __pa(pmd_table) >> PAGE_SHIFT);
                set_pgd(pgd, __pgd(__pa(pmd_table) | _PAGE_PRESENT));
                pud = pud_offset(pgd, 0);
                BUG_ON(pmd_table != pmd_offset(pud, 0));

                return pmd_table;
        }
#endif
        pud = pud_offset(pgd, 0);
        pmd_table = pmd_offset(pud, 0);

        return pmd_table;
}

/*
 * Create a page table and place a pointer to it in a middle page
 * directory entry:
 */
static pte_t * __init one_page_table_init(pmd_t *pmd)
{
        if (!(pmd_val(*pmd) & _PAGE_PRESENT)) {
                pte_t *page_table = NULL;

                if (after_init_bootmem) {
#ifdef CONFIG_DEBUG_PAGEALLOC
                        page_table = (pte_t *) alloc_bootmem_pages(PAGE_SIZE);
#endif
                        if (!page_table)
                                page_table =
                                (pte_t *)alloc_bootmem_low_pages(PAGE_SIZE);
                } else
                        page_table = (pte_t *)alloc_low_page();

                paravirt_alloc_pte(&init_mm, __pa(page_table) >> PAGE_SHIFT);
                set_pmd(pmd, __pmd(__pa(page_table) | _PAGE_TABLE));
                BUG_ON(page_table != pte_offset_kernel(pmd, 0));
        }

        return pte_offset_kernel(pmd, 0);
}

static pte_t *__init page_table_kmap_check(pte_t *pte, pmd_t *pmd,
                                           unsigned long vaddr, pte_t *lastpte)
{
#ifdef CONFIG_HIGHMEM
        /*
         * Something (early fixmap) may already have put a pte
         * page here, which causes the page table allocation
         * to become nonlinear. Attempt to fix it, and if it
         * is still nonlinear then we have to bug.
         */
        int pmd_idx_kmap_begin = fix_to_virt(FIX_KMAP_END) >> PMD_SHIFT;
        int pmd_idx_kmap_end = fix_to_virt(FIX_KMAP_BEGIN) >> PMD_SHIFT;

        if (pmd_idx_kmap_begin != pmd_idx_kmap_end
            && (vaddr >> PMD_SHIFT) >= pmd_idx_kmap_begin
            && (vaddr >> PMD_SHIFT) <= pmd_idx_kmap_end
            && ((__pa(pte) >> PAGE_SHIFT) < table_start
                || (__pa(pte) >> PAGE_SHIFT) >= table_end)) {
                pte_t *newpte;
                int i;

                BUG_ON(after_init_bootmem);
                newpte = alloc_low_page();
                for (i = 0; i < PTRS_PER_PTE; i++)
                        set_pte(newpte + i, pte[i]);

                paravirt_alloc_pte(&init_mm, __pa(newpte) >> PAGE_SHIFT);
                set_pmd(pmd, __pmd(__pa(newpte)|_PAGE_TABLE));
                BUG_ON(newpte != pte_offset_kernel(pmd, 0));
                __flush_tlb_all();

                paravirt_release_pte(__pa(pte) >> PAGE_SHIFT);
                pte = newpte;
        }
        BUG_ON(vaddr < fix_to_virt(FIX_KMAP_BEGIN - 1)
               && vaddr > fix_to_virt(FIX_KMAP_END)
               && lastpte && lastpte + PTRS_PER_PTE != pte);
#endif
        return pte;
}

/*
 * This function initializes a certain range of kernel virtual memory
 * with new bootmem page tables, everywhere page tables are missing in
 * the given range.
 *
 * NOTE: The pagetables are allocated contiguous on the physical space
 * so we can cache the place of the first one and move around without
 * checking the pgd every time.
 */
static void __init
page_table_range_init(unsigned long start, unsigned long end, pgd_t *pgd_base)
{
        int pgd_idx, pmd_idx;
        unsigned long vaddr;
        pgd_t *pgd;
        pmd_t *pmd;
        pte_t *pte = NULL;

        vaddr = start;
        pgd_idx = pgd_index(vaddr);
        pmd_idx = pmd_index(vaddr);
        pgd = pgd_base + pgd_idx;

        for ( ; (pgd_idx < PTRS_PER_PGD) && (vaddr != end); pgd++, pgd_idx++) {
                pmd = one_md_table_init(pgd);
                pmd = pmd + pmd_index(vaddr);
                for (; (pmd_idx < PTRS_PER_PMD) && (vaddr != end);
                                                        pmd++, pmd_idx++) {
                        pte = page_table_kmap_check(one_page_table_init(pmd),
                                                    pmd, vaddr, pte);

                        vaddr += PMD_SIZE;
                }
                pmd_idx = 0;
        }
}

static inline int is_kernel_text(unsigned long addr)
{
        if (addr >= PAGE_OFFSET && addr <= (unsigned long)__init_end)
                return 1;
        return 0;
}

/*
 * This maps the physical memory to kernel virtual address space, a total
 * of max_low_pfn pages, by creating page tables starting from address
 * PAGE_OFFSET:
 */
static void __init kernel_physical_mapping_init(pgd_t *pgd_base,
                                                unsigned long start_pfn,
                                                unsigned long end_pfn,
                                                int use_pse)
{
        int pgd_idx, pmd_idx, pte_ofs;
        unsigned long pfn;
        pgd_t *pgd;
        pmd_t *pmd;
        pte_t *pte;
        unsigned pages_2m, pages_4k;
        int mapping_iter;

        /*
         * First iteration will setup identity mapping using large/small pages
         * based on use_pse, with other attributes same as set by
         * the early code in head_32.S
         *
         * Second iteration will setup the appropriate attributes (NX, GLOBAL..)
         * as desired for the kernel identity mapping.
         *
         * This two pass mechanism conforms to the TLB app note which says:
         *
         *     "Software should not write to a paging-structure entry in a way
         *      that would change, for any linear address, both the page size
         *      and either the page frame or attributes."
         */
        mapping_iter = 1;

        if (!cpu_has_pse)
                use_pse = 0;

repeat:
        pages_2m = pages_4k = 0;
        pfn = start_pfn;
        pgd_idx = pgd_index((pfn<<PAGE_SHIFT) + PAGE_OFFSET);
        pgd = pgd_base + pgd_idx;
        for (; pgd_idx < PTRS_PER_PGD; pgd++, pgd_idx++) {
                pmd = one_md_table_init(pgd);

                if (pfn >= end_pfn)
                        continue;
#ifdef CONFIG_X86_PAE
                pmd_idx = pmd_index((pfn<<PAGE_SHIFT) + PAGE_OFFSET);
                pmd += pmd_idx;
#else
                pmd_idx = 0;
#endif
                for (; pmd_idx < PTRS_PER_PMD && pfn < end_pfn;
                     pmd++, pmd_idx++) {
                        unsigned int addr = pfn * PAGE_SIZE + PAGE_OFFSET;

                        /*
                         * Map with big pages if possible, otherwise
                         * create normal page tables:
                         */
                        if (use_pse) {
                                unsigned int addr2;
                                pgprot_t prot = PAGE_KERNEL_LARGE;
                                /*
                                 * first pass will use the same initial
                                 * identity mapping attribute + _PAGE_PSE.
                                 */
                                pgprot_t init_prot =
                                        __pgprot(PTE_IDENT_ATTR |
                                                 _PAGE_PSE);

                                addr2 = (pfn + PTRS_PER_PTE-1) * PAGE_SIZE +
                                        PAGE_OFFSET + PAGE_SIZE-1;

                                if (is_kernel_text(addr) ||
                                    is_kernel_text(addr2))
                                        prot = PAGE_KERNEL_LARGE_EXEC;

                                pages_2m++;
                                if (mapping_iter == 1)
                                        set_pmd(pmd, pfn_pmd(pfn, init_prot));
                                else
                                        set_pmd(pmd, pfn_pmd(pfn, prot));

                                pfn += PTRS_PER_PTE;
                                continue;
                        }
                        pte = one_page_table_init(pmd);

                        pte_ofs = pte_index((pfn<<PAGE_SHIFT) + PAGE_OFFSET);
                        pte += pte_ofs;
                        for (; pte_ofs < PTRS_PER_PTE && pfn < end_pfn;
                             pte++, pfn++, pte_ofs++, addr += PAGE_SIZE) {
                                pgprot_t prot = PAGE_KERNEL;
                                /*
                                 * first pass will use the same initial
                                 * identity mapping attribute.
                                 */
                                pgprot_t init_prot = __pgprot(PTE_IDENT_ATTR);

                                if (is_kernel_text(addr))
                                        prot = PAGE_KERNEL_EXEC;

                                pages_4k++;
                                if (mapping_iter == 1)
                                        set_pte(pte, pfn_pte(pfn, init_prot));
                                else
                                        set_pte(pte, pfn_pte(pfn, prot));
                        }
                }
        }
        if (mapping_iter == 1) {
                /*
                 * update direct mapping page count only in the first
                 * iteration.
                 */
                update_page_count(PG_LEVEL_2M, pages_2m);
                update_page_count(PG_LEVEL_4K, pages_4k);

                /*
                 * local global flush tlb, which will flush the previous
                 * mappings present in both small and large page TLB's.
                 */
                __flush_tlb_all();

                /*
                 * Second iteration will set the actual desired PTE attributes.
                 */
                mapping_iter = 2;
                goto repeat;
        }
}

/*
 * devmem_is_allowed() checks to see if /dev/mem access to a certain address
 * is valid. The argument is a physical page number.
 *
 *
 * On x86, access has to be given to the first megabyte of ram because that area
 * contains bios code and data regions used by X and dosemu and similar apps.
 * Access has to be given to non-kernel-ram areas as well, these contain the PCI
 * mmio resources as well as potential bios/acpi data regions.
 */
int devmem_is_allowed(unsigned long pagenr)
{
        if (pagenr <= 256)
                return 1;
        if (iomem_is_exclusive(pagenr << PAGE_SHIFT))
                return 0;
        if (!page_is_ram(pagenr))
                return 1;
        return 0;
}

pte_t *kmap_pte;
pgprot_t kmap_prot;

static inline pte_t *kmap_get_fixmap_pte(unsigned long vaddr)
{
        return pte_offset_kernel(pmd_offset(pud_offset(pgd_offset_k(vaddr),
                        vaddr), vaddr), vaddr);
}

static void __init kmap_init(void)
{
        unsigned long kmap_vstart;

        /*
         * Cache the first kmap pte:
         */
        kmap_vstart = __fix_to_virt(FIX_KMAP_BEGIN);
        kmap_pte = kmap_get_fixmap_pte(kmap_vstart);

        kmap_prot = PAGE_KERNEL;
}

#ifdef CONFIG_HIGHMEM
static void __init permanent_kmaps_init(pgd_t *pgd_base)
{
        unsigned long vaddr;
        pgd_t *pgd;
        pud_t *pud;
        pmd_t *pmd;
        pte_t *pte;

        vaddr = PKMAP_BASE;
        page_table_range_init(vaddr, vaddr + PAGE_SIZE*LAST_PKMAP, pgd_base);

        pgd = swapper_pg_dir + pgd_index(vaddr);
        pud = pud_offset(pgd, vaddr);
        pmd = pmd_offset(pud, vaddr);
        pte = pte_offset_kernel(pmd, vaddr);
        pkmap_page_table = pte;
}

static void __init add_one_highpage_init(struct page *page, int pfn)
{
        ClearPageReserved(page);
        init_page_count(page);
        __free_page(page);
        totalhigh_pages++;
}

struct add_highpages_data {
        unsigned long start_pfn;
        unsigned long end_pfn;
};

static int __init add_highpages_work_fn(unsigned long start_pfn,
                                         unsigned long end_pfn, void *datax)
{
        int node_pfn;
        struct page *page;
        unsigned long final_start_pfn, final_end_pfn;
        struct add_highpages_data *data;

        data = (struct add_highpages_data *)datax;

        final_start_pfn = max(start_pfn, data->start_pfn);
        final_end_pfn = min(end_pfn, data->end_pfn);
        if (final_start_pfn >= final_end_pfn)
                return 0;

        for (node_pfn = final_start_pfn; node_pfn < final_end_pfn;
             node_pfn++) {
                if (!pfn_valid(node_pfn))
                        continue;
                page = pfn_to_page(node_pfn);
                add_one_highpage_init(page, node_pfn);
        }

        return 0;

}

void __init add_highpages_with_active_regions(int nid, unsigned long start_pfn,
                                              unsigned long end_pfn)
{
        struct add_highpages_data data;

        data.start_pfn = start_pfn;
        data.end_pfn = end_pfn;

        work_with_active_regions(nid, add_highpages_work_fn, &data);
}

#ifndef CONFIG_NUMA
static void __init set_highmem_pages_init(void)
{
        add_highpages_with_active_regions(0, highstart_pfn, highend_pfn);

        totalram_pages += totalhigh_pages;
}
#endif /* !CONFIG_NUMA */

#else
static inline void permanent_kmaps_init(pgd_t *pgd_base)
{
}
static inline void set_highmem_pages_init(void)
{
}
#endif /* CONFIG_HIGHMEM */

void __init native_pagetable_setup_start(pgd_t *base)
{
        unsigned long pfn, va;
        pgd_t *pgd;
        pud_t *pud;
        pmd_t *pmd;
        pte_t *pte;

        /*
         * Remove any mappings which extend past the end of physical
         * memory from the boot time page table:
         */
        for (pfn = max_low_pfn + 1; pfn < 1<<(32-PAGE_SHIFT); pfn++) {
                va = PAGE_OFFSET + (pfn<<PAGE_SHIFT);
                pgd = base + pgd_index(va);
                if (!pgd_present(*pgd))
                        break;

                pud = pud_offset(pgd, va);
                pmd = pmd_offset(pud, va);
                if (!pmd_present(*pmd))
                        break;

                pte = pte_offset_kernel(pmd, va);
                if (!pte_present(*pte))
                        break;

                pte_clear(NULL, va, pte);
        }
        paravirt_alloc_pmd(&init_mm, __pa(base) >> PAGE_SHIFT);
}

void __init native_pagetable_setup_done(pgd_t *base)
{
}

/*
 * Build a proper pagetable for the kernel mappings.  Up until this
 * point, we've been running on some set of pagetables constructed by
 * the boot process.
 *
 * If we're booting on native hardware, this will be a pagetable
 * constructed in arch/x86/kernel/head_32.S.  The root of the
 * pagetable will be swapper_pg_dir.
 *
 * If we're booting paravirtualized under a hypervisor, then there are
 * more options: we may already be running PAE, and the pagetable may
 * or may not be based in swapper_pg_dir.  In any case,
 * paravirt_pagetable_setup_start() will set up swapper_pg_dir
 * appropriately for the rest of the initialization to work.
 *
 * In general, pagetable_init() assumes that the pagetable may already
 * be partially populated, and so it avoids stomping on any existing
 * mappings.
 */
static void __init early_ioremap_page_table_range_init(pgd_t *pgd_base)
{
        unsigned long vaddr, end;

        /*
         * Fixed mappings, only the page table structure has to be
         * created - mappings will be set by set_fixmap():
         */
        vaddr = __fix_to_virt(__end_of_fixed_addresses - 1) & PMD_MASK;
        end = (FIXADDR_TOP + PMD_SIZE - 1) & PMD_MASK;
        page_table_range_init(vaddr, end, pgd_base);
        early_ioremap_reset();
}

static void __init pagetable_init(void)
{
        pgd_t *pgd_base = swapper_pg_dir;

        permanent_kmaps_init(pgd_base);
}

#ifdef CONFIG_ACPI_SLEEP
/*
 * ACPI suspend needs this for resume, because things like the intel-agp
 * driver might have split up a kernel 4MB mapping.
 */
char swsusp_pg_dir[PAGE_SIZE]
        __attribute__ ((aligned(PAGE_SIZE)));

static inline void save_pg_dir(void)
{
        memcpy(swsusp_pg_dir, swapper_pg_dir, PAGE_SIZE);
}
#else /* !CONFIG_ACPI_SLEEP */
static inline void save_pg_dir(void)
{
}
#endif /* !CONFIG_ACPI_SLEEP */

void zap_low_mappings(void)
{
        int i;

        /*
         * Zap initial low-memory mappings.
         *
         * Note that "pgd_clear()" doesn't do it for
         * us, because pgd_clear() is a no-op on i386.
         */
        for (i = 0; i < KERNEL_PGD_BOUNDARY; i++) {
#ifdef CONFIG_X86_PAE
                set_pgd(swapper_pg_dir+i, __pgd(1 + __pa(empty_zero_page)));
#else
                set_pgd(swapper_pg_dir+i, __pgd(0));
#endif
        }
        flush_tlb_all();
}

int nx_enabled;

pteval_t __supported_pte_mask __read_mostly = ~(_PAGE_NX | _PAGE_GLOBAL | _PAGE_IOMAP);
EXPORT_SYMBOL_GPL(__supported_pte_mask);

#ifdef CONFIG_X86_PAE

static int disable_nx __initdata;

/*
 * noexec = on|off
 *
 * Control non executable mappings.
 *
 * on      Enable
 * off     Disable
 */
static int __init noexec_setup(char *str)
{
        if (!str || !strcmp(str, "on")) {
                if (cpu_has_nx) {
                        __supported_pte_mask |= _PAGE_NX;
                        disable_nx = 0;
                }
        } else {
                if (!strcmp(str, "off")) {
                        disable_nx = 1;
                        __supported_pte_mask &= ~_PAGE_NX;
                } else {
                        return -EINVAL;
                }
        }

        return 0;
}
early_param("noexec", noexec_setup);

static void __init set_nx(void)
{
        unsigned int v[4], l, h;

        if (cpu_has_pae && (cpuid_eax(0x80000000) > 0x80000001)) {
                cpuid(0x80000001, &v[0], &v[1], &v[2], &v[3]);

                if ((v[3] & (1 << 20)) && !disable_nx) {
                        rdmsr(MSR_EFER, l, h);
                        l |= EFER_NX;
                        wrmsr(MSR_EFER, l, h);
                        nx_enabled = 1;
                        __supported_pte_mask |= _PAGE_NX;
                }
        }
}
#endif

/* user-defined highmem size */
static unsigned int highmem_pages = -1;

/*
 * highmem=size forces highmem to be exactly 'size' bytes.
 * This works even on boxes that have no highmem otherwise.
 * This also works to reduce highmem size on bigger boxes.
 */
static int __init parse_highmem(char *arg)
{
        if (!arg)
                return -EINVAL;

        highmem_pages = memparse(arg, &arg) >> PAGE_SHIFT;
        return 0;
}
early_param("highmem", parse_highmem);

/*
 * Determine low and high memory ranges:
 */
void __init find_low_pfn_range(void)
{
        /* it could update max_pfn */

        /* max_low_pfn is 0, we already have early_res support */

        max_low_pfn = max_pfn;
        if (max_low_pfn > MAXMEM_PFN) {
                if (highmem_pages == -1)
                        highmem_pages = max_pfn - MAXMEM_PFN;
                if (highmem_pages + MAXMEM_PFN < max_pfn)
                        max_pfn = MAXMEM_PFN + highmem_pages;
                if (highmem_pages + MAXMEM_PFN > max_pfn) {
                        printk(KERN_WARNING "only %luMB highmem pages "
                                "available, ignoring highmem size of %uMB.\n",
                                pages_to_mb(max_pfn - MAXMEM_PFN),
                                pages_to_mb(highmem_pages));
                        highmem_pages = 0;
                }
                max_low_pfn = MAXMEM_PFN;
#ifndef CONFIG_HIGHMEM
                /* Maximum memory usable is what is directly addressable */
                printk(KERN_WARNING "Warning only %ldMB will be used.\n",
                                        MAXMEM>>20);
                if (max_pfn > MAX_NONPAE_PFN)
                        printk(KERN_WARNING
                                 "Use a HIGHMEM64G enabled kernel.\n");
                else
                        printk(KERN_WARNING "Use a HIGHMEM enabled kernel.\n");
                max_pfn = MAXMEM_PFN;
#else /* !CONFIG_HIGHMEM */
#ifndef CONFIG_HIGHMEM64G
                if (max_pfn > MAX_NONPAE_PFN) {
                        max_pfn = MAX_NONPAE_PFN;
                        printk(KERN_WARNING "Warning only 4GB will be used."
                                "Use a HIGHMEM64G enabled kernel.\n");
                }
#endif /* !CONFIG_HIGHMEM64G */
#endif /* !CONFIG_HIGHMEM */
        } else {
                if (highmem_pages == -1)
                        highmem_pages = 0;
#ifdef CONFIG_HIGHMEM
                if (highmem_pages >= max_pfn) {
                        printk(KERN_ERR "highmem size specified (%uMB) is "
                                "bigger than pages available (%luMB)!.\n",
                                pages_to_mb(highmem_pages),
                                pages_to_mb(max_pfn));
                        highmem_pages = 0;
                }
                if (highmem_pages) {
                        if (max_low_pfn - highmem_pages <
                            64*1024*1024/PAGE_SIZE){
                                printk(KERN_ERR "highmem size %uMB results in "
                                "smaller than 64MB lowmem, ignoring it.\n"
                                        , pages_to_mb(highmem_pages));
                                highmem_pages = 0;
                        }
                        max_low_pfn -= highmem_pages;
                }
#else
                if (highmem_pages)
                        printk(KERN_ERR "ignoring highmem size on non-highmem"
                                        " kernel!\n");
#endif
        }
}

#ifndef CONFIG_NEED_MULTIPLE_NODES
void __init initmem_init(unsigned long start_pfn,
                                  unsigned long end_pfn)
{
#ifdef CONFIG_HIGHMEM
        highstart_pfn = highend_pfn = max_pfn;
        if (max_pfn > max_low_pfn)
                highstart_pfn = max_low_pfn;
        memory_present(0, 0, highend_pfn);
        e820_register_active_regions(0, 0, highend_pfn);
        printk(KERN_NOTICE "%ldMB HIGHMEM available.\n",
                pages_to_mb(highend_pfn - highstart_pfn));
        num_physpages = highend_pfn;
        high_memory = (void *) __va(highstart_pfn * PAGE_SIZE - 1) + 1;
#else
        memory_present(0, 0, max_low_pfn);
        e820_register_active_regions(0, 0, max_low_pfn);
        num_physpages = max_low_pfn;
        high_memory = (void *) __va(max_low_pfn * PAGE_SIZE - 1) + 1;
#endif
#ifdef CONFIG_FLATMEM
        max_mapnr = num_physpages;
#endif
        printk(KERN_NOTICE "%ldMB LOWMEM available.\n",
                        pages_to_mb(max_low_pfn));

        setup_bootmem_allocator();
}
#endif /* !CONFIG_NEED_MULTIPLE_NODES */

static void __init zone_sizes_init(void)
{
        unsigned long max_zone_pfns[MAX_NR_ZONES];
        memset(max_zone_pfns, 0, sizeof(max_zone_pfns));
        max_zone_pfns[ZONE_DMA] =
                virt_to_phys((char *)MAX_DMA_ADDRESS) >> PAGE_SHIFT;
        max_zone_pfns[ZONE_NORMAL] = max_low_pfn;
#ifdef CONFIG_HIGHMEM
        max_zone_pfns[ZONE_HIGHMEM] = highend_pfn;
#endif

        free_area_init_nodes(max_zone_pfns);
}

void __init setup_bootmem_allocator(void)
{
        int i;
        unsigned long bootmap_size, bootmap;
        /*
         * Initialize the boot-time allocator (with low memory only):
         */
        bootmap_size = bootmem_bootmap_pages(max_low_pfn)<<PAGE_SHIFT;
        bootmap = find_e820_area(min_low_pfn<<PAGE_SHIFT,
                                 max_pfn_mapped<<PAGE_SHIFT, bootmap_size,
                                 PAGE_SIZE);
        if (bootmap == -1L)
                panic("Cannot find bootmem map of size %ld\n", bootmap_size);
        reserve_early(bootmap, bootmap + bootmap_size, "BOOTMAP");

        /* don't touch min_low_pfn */
        bootmap_size = init_bootmem_node(NODE_DATA(0), bootmap >> PAGE_SHIFT,
                                         min_low_pfn, max_low_pfn);
        printk(KERN_INFO "  mapped low ram: 0 - %08lx\n",
                 max_pfn_mapped<<PAGE_SHIFT);
        printk(KERN_INFO "  low ram: %08lx - %08lx\n",
                 min_low_pfn<<PAGE_SHIFT, max_low_pfn<<PAGE_SHIFT);
        printk(KERN_INFO "  bootmap %08lx - %08lx\n",
                 bootmap, bootmap + bootmap_size);
        for_each_online_node(i)
                free_bootmem_with_active_regions(i, max_low_pfn);
        early_res_to_bootmem(0, max_low_pfn<<PAGE_SHIFT);

        after_init_bootmem = 1;
}

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

        puds = (end + PUD_SIZE - 1) >> PUD_SHIFT;
        tables = PAGE_ALIGN(puds * sizeof(pud_t));

        pmds = (end + PMD_SIZE - 1) >> PMD_SHIFT;
        tables += PAGE_ALIGN(pmds * sizeof(pmd_t));

        if (use_pse) {
                unsigned long extra;

                extra = end - ((end>>PMD_SHIFT) << PMD_SHIFT);
                extra += PMD_SIZE;
                ptes = (extra + PAGE_SIZE - 1) >> PAGE_SHIFT;
        } else
                ptes = (end + PAGE_SIZE - 1) >> PAGE_SHIFT;

        tables += PAGE_ALIGN(ptes * sizeof(pte_t));

        /* for fixmap */
        tables += PAGE_ALIGN(__end_of_fixed_addresses * sizeof(pte_t));

        /*
         * 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 = 0x7000;
        table_start = find_e820_area(start, max_pfn_mapped<<PAGE_SHIFT,
                                        tables, PAGE_SIZE);
        if (table_start == -1UL)
                panic("Cannot find space for the kernel page tables");

        table_start >>= PAGE_SHIFT;
        table_end = table_start;
        table_top = table_start + (tables>>PAGE_SHIFT);

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

unsigned long __init_refok init_memory_mapping(unsigned long start,
                                                unsigned long end)
{
        pgd_t *pgd_base = swapper_pg_dir;
        unsigned long start_pfn, end_pfn;
        unsigned long big_page_start;
#ifdef CONFIG_DEBUG_PAGEALLOC
        /*
         * For CONFIG_DEBUG_PAGEALLOC, identity mapping will use small pages.
         * This will simplify cpa(), which otherwise needs to support splitting
         * large pages into small in interrupt context, etc.
         */
        int use_pse = 0;
#else
        int use_pse = cpu_has_pse;
#endif

        /*
         * Find space for the kernel direct mapping tables.
         */
        if (!after_init_bootmem)
                find_early_table_space(end, use_pse);

#ifdef CONFIG_X86_PAE
        set_nx();
        if (nx_enabled)
                printk(KERN_INFO "NX (Execute Disable) protection: active\n");
#endif

        /* Enable PSE if available */
        if (cpu_has_pse)
                set_in_cr4(X86_CR4_PSE);

        /* Enable PGE if available */
        if (cpu_has_pge) {
                set_in_cr4(X86_CR4_PGE);
                __supported_pte_mask |= _PAGE_GLOBAL;
        }

        /*
         * Don't use a large page for the first 2/4MB of memory
         * because there are often fixed size MTRRs in there
         * and overlapping MTRRs into large pages can cause
         * slowdowns.
         */
        big_page_start = PMD_SIZE;

        if (start < big_page_start) {
                start_pfn = start >> PAGE_SHIFT;
                end_pfn = min(big_page_start>>PAGE_SHIFT, end>>PAGE_SHIFT);
        } else {
                /* head is not big page alignment ? */
                start_pfn = start >> PAGE_SHIFT;
                end_pfn = ((start + (PMD_SIZE - 1))>>PMD_SHIFT)
                                 << (PMD_SHIFT - PAGE_SHIFT);
        }
        if (start_pfn < end_pfn)
                kernel_physical_mapping_init(pgd_base, start_pfn, end_pfn, 0);

        /* big page range */
        start_pfn = ((start + (PMD_SIZE - 1))>>PMD_SHIFT)
                         << (PMD_SHIFT - PAGE_SHIFT);
        if (start_pfn < (big_page_start >> PAGE_SHIFT))
                start_pfn =  big_page_start >> PAGE_SHIFT;
        end_pfn = (end>>PMD_SHIFT) << (PMD_SHIFT - PAGE_SHIFT);
        if (start_pfn < end_pfn)
                kernel_physical_mapping_init(pgd_base, start_pfn, end_pfn,
                                             use_pse);

        /* tail is not big page alignment ? */
        start_pfn = end_pfn;
        if (start_pfn > (big_page_start>>PAGE_SHIFT)) {
                end_pfn = end >> PAGE_SHIFT;
                if (start_pfn < end_pfn)
                        kernel_physical_mapping_init(pgd_base, start_pfn,
                                                         end_pfn, 0);
        }

        early_ioremap_page_table_range_init(pgd_base);

        load_cr3(swapper_pg_dir);

        __flush_tlb_all();

        if (!after_init_bootmem)
                reserve_early(table_start << PAGE_SHIFT,
                                 table_end << PAGE_SHIFT, "PGTABLE");

        if (!after_init_bootmem)
                early_memtest(start, end);

        return end >> PAGE_SHIFT;
}


/*
 * paging_init() sets up the page tables - note that the first 8MB are
 * already mapped by head.S.
 *
 * This routines also unmaps the page at virtual kernel address 0, so
 * that we can trap those pesky NULL-reference errors in the kernel.
 */
void __init paging_init(void)
{
        pagetable_init();

        __flush_tlb_all();

        kmap_init();

        /*
         * NOTE: at this point the bootmem allocator is fully available.
         */
        sparse_init();
        zone_sizes_init();
}

/*
 * Test if the WP bit works in supervisor mode. It isn't supported on 386's
 * and also on some strange 486's. All 586+'s are OK. This used to involve
 * black magic jumps to work around some nasty CPU bugs, but fortunately the
 * switch to using exceptions got rid of all that.
 */
static void __init test_wp_bit(void)
{
        printk(KERN_INFO
  "Checking if this processor honours the WP bit even in supervisor mode...");

        /* Any page-aligned address will do, the test is non-destructive */
        __set_fixmap(FIX_WP_TEST, __pa(&swapper_pg_dir), PAGE_READONLY);
        boot_cpu_data.wp_works_ok = do_test_wp_bit();
        clear_fixmap(FIX_WP_TEST);

        if (!boot_cpu_data.wp_works_ok) {
                printk(KERN_CONT "No.\n");
#ifdef CONFIG_X86_WP_WORKS_OK
                panic(
  "This kernel doesn't support CPU's with broken WP. Recompile it for a 386!");
#endif
        } else {
                printk(KERN_CONT "Ok.\n");
        }
}

static struct kcore_list kcore_mem, kcore_vmalloc;

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

        pci_iommu_alloc();

#ifdef CONFIG_FLATMEM
        BUG_ON(!mem_map);
#endif
        /* this will put all low memory onto the freelists */
        totalram_pages += free_all_bootmem();

        reservedpages = 0;
        for (tmp = 0; tmp < max_low_pfn; tmp++)
                /*
                 * Only count reserved RAM pages:
                 */
                if (page_is_ram(tmp) && PageReserved(pfn_to_page(tmp)))
                        reservedpages++;

        set_highmem_pages_init();

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

        kclist_add(&kcore_mem, __va(0), max_low_pfn << PAGE_SHIFT);
        kclist_add(&kcore_vmalloc, (void *)VMALLOC_START,
                   VMALLOC_END-VMALLOC_START);

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

        printk(KERN_INFO "virtual kernel memory layout:\n"
                "    fixmap  : 0x%08lx - 0x%08lx   (%4ld kB)\n"
#ifdef CONFIG_HIGHMEM
                "    pkmap   : 0x%08lx - 0x%08lx   (%4ld kB)\n"
#endif
                "    vmalloc : 0x%08lx - 0x%08lx   (%4ld MB)\n"
                "    lowmem  : 0x%08lx - 0x%08lx   (%4ld MB)\n"
                "      .init : 0x%08lx - 0x%08lx   (%4ld kB)\n"
                "      .data : 0x%08lx - 0x%08lx   (%4ld kB)\n"
                "      .text : 0x%08lx - 0x%08lx   (%4ld kB)\n",
                FIXADDR_START, FIXADDR_TOP,
                (FIXADDR_TOP - FIXADDR_START) >> 10,

#ifdef CONFIG_HIGHMEM
                PKMAP_BASE, PKMAP_BASE+LAST_PKMAP*PAGE_SIZE,
                (LAST_PKMAP*PAGE_SIZE) >> 10,
#endif

                VMALLOC_START, VMALLOC_END,
                (VMALLOC_END - VMALLOC_START) >> 20,

                (unsigned long)__va(0), (unsigned long)high_memory,
                ((unsigned long)high_memory - (unsigned long)__va(0)) >> 20,

                (unsigned long)&__init_begin, (unsigned long)&__init_end,
                ((unsigned long)&__init_end -
                 (unsigned long)&__init_begin) >> 10,

                (unsigned long)&_etext, (unsigned long)&_edata,
                ((unsigned long)&_edata - (unsigned long)&_etext) >> 10,

                (unsigned long)&_text, (unsigned long)&_etext,
                ((unsigned long)&_etext - (unsigned long)&_text) >> 10);

        /*
         * Check boundaries twice: Some fundamental inconsistencies can
         * be detected at build time already.
         */
#define __FIXADDR_TOP (-PAGE_SIZE)
#ifdef CONFIG_HIGHMEM
        BUILD_BUG_ON(PKMAP_BASE + LAST_PKMAP*PAGE_SIZE  > FIXADDR_START);
        BUILD_BUG_ON(VMALLOC_END                        > PKMAP_BASE);
#endif
#define high_memory (-128UL << 20)
        BUILD_BUG_ON(VMALLOC_START                      >= VMALLOC_END);
#undef high_memory
#undef __FIXADDR_TOP

#ifdef CONFIG_HIGHMEM
        BUG_ON(PKMAP_BASE + LAST_PKMAP*PAGE_SIZE        > FIXADDR_START);
        BUG_ON(VMALLOC_END                              > PKMAP_BASE);
#endif
        BUG_ON(VMALLOC_START                            >= VMALLOC_END);
        BUG_ON((unsigned long)high_memory               > VMALLOC_START);

        if (boot_cpu_data.wp_works_ok < 0)
                test_wp_bit();

        save_pg_dir();
        zap_low_mappings();
}

#ifdef CONFIG_MEMORY_HOTPLUG
int arch_add_memory(int nid, u64 start, u64 size)
{
        struct pglist_data *pgdata = NODE_DATA(nid);
        struct zone *zone = pgdata->node_zones + ZONE_HIGHMEM;
        unsigned long start_pfn = start >> PAGE_SHIFT;
        unsigned long nr_pages = size >> PAGE_SHIFT;

        return __add_pages(nid, zone, start_pfn, nr_pages);
}
#endif

/*
 * This function cannot be __init, since exceptions don't work in that
 * section.  Put this after the callers, so that it cannot be inlined.
 */
static noinline int do_test_wp_bit(void)
{
        char tmp_reg;
        int flag;

        __asm__ __volatile__(
                "       movb %0, %1     \n"
                "1:     movb %1, %0     \n"
                "       xorl %2, %2     \n"
                "2:                     \n"
                _ASM_EXTABLE(1b,2b)
                :"=m" (*(char *)fix_to_virt(FIX_WP_TEST)),
                 "=q" (tmp_reg),
                 "=r" (flag)
                :"2" (1)
                :"memory");

        return flag;
}

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

void mark_rodata_ro(void)
{
        unsigned long start = PFN_ALIGN(_text);
        unsigned long size = PFN_ALIGN(_etext) - start;

#ifndef CONFIG_DYNAMIC_FTRACE
        /* Dynamic tracing modifies the kernel text section */
        set_pages_ro(virt_to_page(start), size >> PAGE_SHIFT);
        printk(KERN_INFO "Write protecting the kernel text: %luk\n",
                size >> 10);

#ifdef CONFIG_CPA_DEBUG
        printk(KERN_INFO "Testing CPA: Reverting %lx-%lx\n",
                start, start+size);
        set_pages_rw(virt_to_page(start), size>>PAGE_SHIFT);

        printk(KERN_INFO "Testing CPA: write protecting again\n");
        set_pages_ro(virt_to_page(start), size>>PAGE_SHIFT);
#endif
#endif /* CONFIG_DYNAMIC_FTRACE */

        start += size;
        size = (unsigned long)__end_rodata - start;
        set_pages_ro(virt_to_page(start), size >> PAGE_SHIFT);
        printk(KERN_INFO "Write protecting the kernel read-only data: %luk\n",
                size >> 10);
        rodata_test();

#ifdef CONFIG_CPA_DEBUG
        printk(KERN_INFO "Testing CPA: undo %lx-%lx\n", start, start + size);
        set_pages_rw(virt_to_page(start), size >> PAGE_SHIFT);

        printk(KERN_INFO "Testing CPA: write protecting again\n");
        set_pages_ro(virt_to_page(start), size >> PAGE_SHIFT);
#endif
}
#endif

void free_init_pages(char *what, unsigned long begin, unsigned long end)
{
#ifdef CONFIG_DEBUG_PAGEALLOC
        /*
         * 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:
         */
        printk(KERN_INFO "debug: unmapping init memory %08lx..%08lx\n",
                begin, PAGE_ALIGN(end));
        set_memory_np(begin, (end - begin) >> PAGE_SHIFT);
#else
        unsigned long addr;

        /*
         * We just marked the kernel text read only above, now that
         * we are going to free part of that, we need to make that
         * writeable first.
         */
        set_memory_rw(begin, (end - begin) >> PAGE_SHIFT);

        for (addr = begin; addr < end; addr += PAGE_SIZE) {
                ClearPageReserved(virt_to_page(addr));
                init_page_count(virt_to_page(addr));
                memset((void *)addr, POISON_FREE_INITMEM, PAGE_SIZE);
                free_page(addr);
                totalram_pages++;
        }
        printk(KERN_INFO "Freeing %s: %luk freed\n", what, (end - begin) >> 10);
#endif
}

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

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

int __init reserve_bootmem_generic(unsigned long phys, unsigned long len,
                                   int flags)
{
        return reserve_bootmem(phys, len, flags);
}