mem.c

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/*
 * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
 * Licensed under the GPL
 */

#include <linux/stddef.h>
#include <linux/module.h>
#include <linux/bootmem.h>
#include <linux/highmem.h>
#include <linux/mm.h>
#include <linux/swap.h>
#include <linux/slab.h>
#include <asm/fixmap.h>
#include <asm/page.h>
#include <as-layout.h>
#include <init.h>
#include <kern.h>
#include <kern_util.h>
#include <mem_user.h>
#include <os.h>

/* allocated in paging_init, zeroed in mem_init, and unchanged thereafter */
unsigned long *empty_zero_page = NULL;
EXPORT_SYMBOL(empty_zero_page);
/* allocated in paging_init and unchanged thereafter */
static unsigned long *empty_bad_page = NULL;

/*
 * Initialized during boot, and readonly for initializing page tables
 * afterwards
 */
pgd_t swapper_pg_dir[PTRS_PER_PGD];

/* Initialized at boot time, and readonly after that */
unsigned long long highmem;
int kmalloc_ok = 0;

/* Used during early boot */
static unsigned long brk_end;

#ifdef CONFIG_HIGHMEM
static void setup_highmem(unsigned long highmem_start,
              unsigned long highmem_len)
{
    struct page *page;
    unsigned long highmem_pfn;
    int i;

    highmem_pfn = __pa(highmem_start) >> PAGE_SHIFT;
    for (i = 0; i < highmem_len >> PAGE_SHIFT; i++) {
        page = &mem_map[highmem_pfn + i];
        ClearPageReserved(page);
        init_page_count(page);
        __free_page(page);
    }
}
#endif

void __init mem_init(void)
{
    /* clear the zero-page */
    memset(empty_zero_page, 0, PAGE_SIZE);

    /* Map in the area just after the brk now that kmalloc is about
     * to be turned on.
     */
    brk_end = (unsigned long) UML_ROUND_UP(sbrk(0));
    map_memory(brk_end, __pa(brk_end), uml_reserved - brk_end, 1, 1, 0);
    free_bootmem(__pa(brk_end), uml_reserved - brk_end);
    uml_reserved = brk_end;

    /* this will put all low memory onto the freelists */
    totalram_pages = free_all_bootmem();
    max_low_pfn = totalram_pages;
#ifdef CONFIG_HIGHMEM
    totalhigh_pages = highmem >> PAGE_SHIFT;
    totalram_pages += totalhigh_pages;
#endif
    num_physpages = totalram_pages;
    max_pfn = totalram_pages;
    printk(KERN_INFO "Memory: %luk available\n",
           nr_free_pages() << (PAGE_SHIFT-10));
    kmalloc_ok = 1;

#ifdef CONFIG_HIGHMEM
    setup_highmem(end_iomem, highmem);
#endif
}

/*
 * Create a page table and place a pointer to it in a middle page
 * directory entry.
 */
static void __init one_page_table_init(pmd_t *pmd)
{
    if (pmd_none(*pmd)) {
        pte_t *pte = (pte_t *) alloc_bootmem_low_pages(PAGE_SIZE);
        set_pmd(pmd, __pmd(_KERNPG_TABLE +
                       (unsigned long) __pa(pte)));
        if (pte != pte_offset_kernel(pmd, 0))
            BUG();
    }
}

static void __init one_md_table_init(pud_t *pud)
{
#ifdef CONFIG_3_LEVEL_PGTABLES
    pmd_t *pmd_table = (pmd_t *) alloc_bootmem_low_pages(PAGE_SIZE);
    set_pud(pud, __pud(_KERNPG_TABLE + (unsigned long) __pa(pmd_table)));
    if (pmd_table != pmd_offset(pud, 0))
        BUG();
#endif
}

static void __init fixrange_init(unsigned long start, unsigned long end,
                 pgd_t *pgd_base)
{
    pgd_t *pgd;
    pud_t *pud;
    pmd_t *pmd;
    int i, j;
    unsigned long vaddr;

    vaddr = start;
    i = pgd_index(vaddr);
    j = pmd_index(vaddr);
    pgd = pgd_base + i;

    for ( ; (i < PTRS_PER_PGD) && (vaddr < end); pgd++, i++) {
        pud = pud_offset(pgd, vaddr);
        if (pud_none(*pud))
            one_md_table_init(pud);
        pmd = pmd_offset(pud, vaddr);
        for (; (j < PTRS_PER_PMD) && (vaddr < end); pmd++, j++) {
            one_page_table_init(pmd);
            vaddr += PMD_SIZE;
        }
        j = 0;
    }
}

#ifdef CONFIG_HIGHMEM
pte_t *kmap_pte;
pgprot_t kmap_prot;

#define kmap_get_fixmap_pte(vaddr)                  \
    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;
}

static void __init init_highmem(void)
{
    pgd_t *pgd;
    pud_t *pud;
    pmd_t *pmd;
    pte_t *pte;
    unsigned long vaddr;

    /*
     * Permanent kmaps:
     */
    vaddr = PKMAP_BASE;
    fixrange_init(vaddr, vaddr + PAGE_SIZE*LAST_PKMAP, swapper_pg_dir);

    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;

    kmap_init();
}
#endif /* CONFIG_HIGHMEM */

static void __init fixaddr_user_init( void)
{
#ifdef CONFIG_ARCH_REUSE_HOST_VSYSCALL_AREA
    long size = FIXADDR_USER_END - FIXADDR_USER_START;
    pgd_t *pgd;
    pud_t *pud;
    pmd_t *pmd;
    pte_t *pte;
    phys_t p;
    unsigned long v, vaddr = FIXADDR_USER_START;

    if (!size)
        return;

    fixrange_init( FIXADDR_USER_START, FIXADDR_USER_END, swapper_pg_dir);
    v = (unsigned long) alloc_bootmem_low_pages(size);
    memcpy((void *) v , (void *) FIXADDR_USER_START, size);
    p = __pa(v);
    for ( ; size > 0; size -= PAGE_SIZE, vaddr += PAGE_SIZE,
              p += PAGE_SIZE) {
        pgd = swapper_pg_dir + pgd_index(vaddr);
        pud = pud_offset(pgd, vaddr);
        pmd = pmd_offset(pud, vaddr);
        pte = pte_offset_kernel(pmd, vaddr);
        pte_set_val(*pte, p, PAGE_READONLY);
    }
#endif
}

void __init paging_init(void)
{
    unsigned long zones_size[MAX_NR_ZONES], vaddr;
    int i;

    empty_zero_page = (unsigned long *) alloc_bootmem_low_pages(PAGE_SIZE);
    empty_bad_page = (unsigned long *) alloc_bootmem_low_pages(PAGE_SIZE);
    for (i = 0; i < ARRAY_SIZE(zones_size); i++)
        zones_size[i] = 0;

    zones_size[ZONE_NORMAL] = (end_iomem >> PAGE_SHIFT) -
        (uml_physmem >> PAGE_SHIFT);
#ifdef CONFIG_HIGHMEM
    zones_size[ZONE_HIGHMEM] = highmem >> PAGE_SHIFT;
#endif
    free_area_init(zones_size);

    /*
     * 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;
    fixrange_init(vaddr, FIXADDR_TOP, swapper_pg_dir);

    fixaddr_user_init();

#ifdef CONFIG_HIGHMEM
    init_highmem();
#endif
}

/*
 * This can't do anything because nothing in the kernel image can be freed
 * since it's not in kernel physical memory.
 */

void free_initmem(void)
{
}

#ifdef CONFIG_BLK_DEV_INITRD
void free_initrd_mem(unsigned long start, unsigned long end)
{
    if (start < end)
        printk(KERN_INFO "Freeing initrd memory: %ldk freed\n",
               (end - start) >> 10);
    for (; start < end; start += PAGE_SIZE) {
        ClearPageReserved(virt_to_page(start));
        init_page_count(virt_to_page(start));
        free_page(start);
        totalram_pages++;
    }
}
#endif

/* Allocate and free page tables. */

pgd_t *pgd_alloc(struct mm_struct *mm)
{
    pgd_t *pgd = (pgd_t *)__get_free_page(GFP_KERNEL);

    if (pgd) {
        memset(pgd, 0, USER_PTRS_PER_PGD * sizeof(pgd_t));
        memcpy(pgd + USER_PTRS_PER_PGD,
               swapper_pg_dir + USER_PTRS_PER_PGD,
               (PTRS_PER_PGD - USER_PTRS_PER_PGD) * sizeof(pgd_t));
    }
    return pgd;
}

void pgd_free(struct mm_struct *mm, pgd_t *pgd)
{
    free_page((unsigned long) pgd);
}

pte_t *pte_alloc_one_kernel(struct mm_struct *mm, unsigned long address)
{
    pte_t *pte;

    pte = (pte_t *)__get_free_page(GFP_KERNEL|__GFP_REPEAT|__GFP_ZERO);
    return pte;
}

pgtable_t pte_alloc_one(struct mm_struct *mm, unsigned long address)
{
    struct page *pte;

    pte = alloc_page(GFP_KERNEL|__GFP_REPEAT|__GFP_ZERO);
    if (pte)
        pgtable_page_ctor(pte);
    return pte;
}

#ifdef CONFIG_3_LEVEL_PGTABLES
pmd_t *pmd_alloc_one(struct mm_struct *mm, unsigned long address)
{
    pmd_t *pmd = (pmd_t *) __get_free_page(GFP_KERNEL);

    if (pmd)
        memset(pmd, 0, PAGE_SIZE);

    return pmd;
}
#endif

void *uml_kmalloc(int size, int flags)
{
    return kmalloc(size, flags);
}