pgd.c

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/*
 *  linux/arch/arm/mm/pgd.c
 *
 *  Copyright (C) 1998-2005 Russell King
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */
#include <linux/mm.h>
#include <linux/gfp.h>
#include <linux/highmem.h>
#include <linux/slab.h>

#include <asm/cp15.h>
#include <asm/pgalloc.h>
#include <asm/page.h>
#include <asm/tlbflush.h>

#include "mm.h"

#ifdef CONFIG_ARM_LPAE
#define __pgd_alloc()   kmalloc(PTRS_PER_PGD * sizeof(pgd_t), GFP_KERNEL)
#define __pgd_free(pgd) kfree(pgd)
#else
#define __pgd_alloc()   (pgd_t *)__get_free_pages(GFP_KERNEL, 2)
#define __pgd_free(pgd) free_pages((unsigned long)pgd, 2)
#endif

/*
 * need to get a 16k page for level 1
 */
pgd_t *pgd_alloc(struct mm_struct *mm)
{
    pgd_t *new_pgd, *init_pgd;
    pud_t *new_pud, *init_pud;
    pmd_t *new_pmd, *init_pmd;
    pte_t *new_pte, *init_pte;

    new_pgd = __pgd_alloc();
    if (!new_pgd)
        goto no_pgd;

    memset(new_pgd, 0, USER_PTRS_PER_PGD * sizeof(pgd_t));

    /*
     * Copy over the kernel and IO PGD entries
     */
    init_pgd = pgd_offset_k(0);
    memcpy(new_pgd + USER_PTRS_PER_PGD, init_pgd + USER_PTRS_PER_PGD,
               (PTRS_PER_PGD - USER_PTRS_PER_PGD) * sizeof(pgd_t));

    clean_dcache_area(new_pgd, PTRS_PER_PGD * sizeof(pgd_t));

#ifdef CONFIG_ARM_LPAE
    /*
     * Allocate PMD table for modules and pkmap mappings.
     */
    new_pud = pud_alloc(mm, new_pgd + pgd_index(MODULES_VADDR),
                MODULES_VADDR);
    if (!new_pud)
        goto no_pud;

    new_pmd = pmd_alloc(mm, new_pud, 0);
    if (!new_pmd)
        goto no_pmd;
#endif

    if (!vectors_high()) {
        /*
         * On ARM, first page must always be allocated since it
         * contains the machine vectors. The vectors are always high
         * with LPAE.
         */
        new_pud = pud_alloc(mm, new_pgd, 0);
        if (!new_pud)
            goto no_pud;

        new_pmd = pmd_alloc(mm, new_pud, 0);
        if (!new_pmd)
            goto no_pmd;

        new_pte = pte_alloc_map(mm, NULL, new_pmd, 0);
        if (!new_pte)
            goto no_pte;

        init_pud = pud_offset(init_pgd, 0);
        init_pmd = pmd_offset(init_pud, 0);
        init_pte = pte_offset_map(init_pmd, 0);
        set_pte_ext(new_pte, *init_pte, 0);
        pte_unmap(init_pte);
        pte_unmap(new_pte);
    }

    return new_pgd;

no_pte:
    pmd_free(mm, new_pmd);
no_pmd:
    pud_free(mm, new_pud);
no_pud:
    __pgd_free(new_pgd);
no_pgd:
    return NULL;
}

void pgd_free(struct mm_struct *mm, pgd_t *pgd_base)
{
    pgd_t *pgd;
    pud_t *pud;
    pmd_t *pmd;
    pgtable_t pte;

    if (!pgd_base)
        return;

    pgd = pgd_base + pgd_index(0);
    if (pgd_none_or_clear_bad(pgd))
        goto no_pgd;

    pud = pud_offset(pgd, 0);
    if (pud_none_or_clear_bad(pud))
        goto no_pud;

    pmd = pmd_offset(pud, 0);
    if (pmd_none_or_clear_bad(pmd))
        goto no_pmd;

    pte = pmd_pgtable(*pmd);
    pmd_clear(pmd);
    pte_free(mm, pte);
no_pmd:
    pud_clear(pud);
    pmd_free(mm, pmd);
no_pud:
    pgd_clear(pgd);
    pud_free(mm, pud);
no_pgd:
#ifdef CONFIG_ARM_LPAE
    /*
     * Free modules/pkmap or identity pmd tables.
     */
    for (pgd = pgd_base; pgd < pgd_base + PTRS_PER_PGD; pgd++) {
        if (pgd_none_or_clear_bad(pgd))
            continue;
        if (pgd_val(*pgd) & L_PGD_SWAPPER)
            continue;
        pud = pud_offset(pgd, 0);
        if (pud_none_or_clear_bad(pud))
            continue;
        pmd = pmd_offset(pud, 0);
        pud_clear(pud);
        pmd_free(mm, pmd);
        pgd_clear(pgd);
        pud_free(mm, pud);
    }
#endif
    __pgd_free(pgd_base);
}