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

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * PGD allocation/freeing
   4 *
   5 * Copyright (C) 2012 ARM Ltd.
   6 * Author: Catalin Marinas <catalin.marinas@arm.com>
   7 */
   8
   9#include <linux/mm.h>
  10#include <linux/gfp.h>
  11#include <linux/highmem.h>
  12#include <linux/slab.h>
  13
  14#include <asm/pgalloc.h>
  15#include <asm/page.h>
  16#include <asm/tlbflush.h>
  17
  18static struct kmem_cache *pgd_cache __ro_after_init;
  19
  20pgd_t *pgd_alloc(struct mm_struct *mm)
  21{
  22        gfp_t gfp = GFP_PGTABLE_USER;
  23
  24        if (PGD_SIZE == PAGE_SIZE)
  25                return (pgd_t *)__get_free_page(gfp);
  26        else
  27                return kmem_cache_alloc(pgd_cache, gfp);
  28}
  29
  30void pgd_free(struct mm_struct *mm, pgd_t *pgd)
  31{
  32        if (PGD_SIZE == PAGE_SIZE)
  33                free_page((unsigned long)pgd);
  34        else
  35                kmem_cache_free(pgd_cache, pgd);
  36}
  37
  38void __init pgtable_cache_init(void)
  39{
  40        if (PGD_SIZE == PAGE_SIZE)
  41                return;
  42
  43#ifdef CONFIG_ARM64_PA_BITS_52
  44        /*
  45         * With 52-bit physical addresses, the architecture requires the
  46         * top-level table to be aligned to at least 64 bytes.
  47         */
  48        BUILD_BUG_ON(PGD_SIZE < 64);
  49#endif
  50
  51        /*
  52         * Naturally aligned pgds required by the architecture.
  53         */
  54        pgd_cache = kmem_cache_create("pgd_cache", PGD_SIZE, PGD_SIZE,
  55                                      SLAB_PANIC, NULL);
  56}
  57