pgd.c

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/*
 * linux/arch/unicore32/mm/pgd.c
 *
 * Code specific to PKUnity SoC and UniCore ISA
 *
 * Copyright (C) 2001-2010 GUAN Xue-tao
 *
 * 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 <asm/pgalloc.h>
#include <asm/page.h>
#include <asm/tlbflush.h>

#include "mm.h"

#define FIRST_KERNEL_PGD_NR (FIRST_USER_PGD_NR + USER_PTRS_PER_PGD)

/*
 * need to get a 4k page for level 1
 */
pgd_t *get_pgd_slow(struct mm_struct *mm)
{
    pgd_t *new_pgd, *init_pgd;
    pmd_t *new_pmd, *init_pmd;
    pte_t *new_pte, *init_pte;

    new_pgd = (pgd_t *)__get_free_pages(GFP_KERNEL, 0);
    if (!new_pgd)
        goto no_pgd;

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

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

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

    if (!vectors_high()) {
        /*
         * On UniCore, first page must always be allocated since it
         * contains the machine vectors.
         */
        new_pmd = pmd_alloc(mm, (pud_t *)new_pgd, 0);
        if (!new_pmd)
            goto no_pmd;

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

        init_pmd = pmd_offset((pud_t *)init_pgd, 0);
        init_pte = pte_offset_map(init_pmd, 0);
        set_pte(new_pte, *init_pte);
        pte_unmap(init_pte);
        pte_unmap(new_pte);
    }

    return new_pgd;

no_pte:
    pmd_free(mm, new_pmd);
no_pmd:
    free_pages((unsigned long)new_pgd, 0);
no_pgd:
    return NULL;
}

void free_pgd_slow(struct mm_struct *mm, pgd_t *pgd)
{
    pmd_t *pmd;
    pgtable_t pte;

    if (!pgd)
        return;

    /* pgd is always present and good */
    pmd = pmd_off(pgd, 0);
    if (pmd_none(*pmd))
        goto free;
    if (pmd_bad(*pmd)) {
        pmd_ERROR(*pmd);
        pmd_clear(pmd);
        goto free;
    }

    pte = pmd_pgtable(*pmd);
    pmd_clear(pmd);
    pte_free(mm, pte);
    pmd_free(mm, pmd);
free:
    free_pages((unsigned long) pgd, 0);
}