LXR linux/arch/arm64/mm/pgd.c

   1/*
   2 * PGD allocation/freeing
   3 *
   4 * Copyright (C) 2012 ARM Ltd.
   5 * Author: Catalin Marinas <catalin.marinas@arm.com>
   6 *
   7 * This program is free software; you can redistribute it and/or modify
   8 * it under the terms of the GNU General Public License version 2 as
   9 * published by the Free Software Foundation.
  10 *
  11 * This program is distributed in the hope that it will be useful,
  12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 * GNU General Public License for more details.
  15 *
  16 * You should have received a copy of the GNU General Public License
  17 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  18 */
  19
  20#include <linux/mm.h>
  21#include <linux/gfp.h>
  22#include <linux/highmem.h>
  23#include <linux/slab.h>
  24
  25#include <asm/pgalloc.h>
  26#include <asm/page.h>
  27#include <asm/tlbflush.h>
  28
  29static struct kmem_cache *pgd_cache __ro_after_init;
  30
  31pgd_t *pgd_alloc(struct mm_struct *mm)
  32{
  33        if (PGD_SIZE == PAGE_SIZE)
  34                return (pgd_t *)__get_free_page(PGALLOC_GFP);
  35        else
  36                return kmem_cache_alloc(pgd_cache, PGALLOC_GFP);
  37}
  38
  39void pgd_free(struct mm_struct *mm, pgd_t *pgd)
  40{
  41        if (PGD_SIZE == PAGE_SIZE)
  42                free_page((unsigned long)pgd);
  43        else
  44                kmem_cache_free(pgd_cache, pgd);
  45}
  46
  47void __init pgd_cache_init(void)
  48{
  49        if (PGD_SIZE == PAGE_SIZE)
  50                return;
  51
  52#ifdef CONFIG_ARM64_PA_BITS_52
  53        /*
  54         * With 52-bit physical addresses, the architecture requires the
  55         * top-level table to be aligned to at least 64 bytes.
  56         */
  57        BUILD_BUG_ON(PGD_SIZE < 64);
  58#endif
  59
  60        /*
  61         * Naturally aligned pgds required by the architecture.
  62         */
  63        pgd_cache = kmem_cache_create("pgd_cache", PGD_SIZE, PGD_SIZE,
  64                                      SLAB_PANIC, NULL);
  65}
  66