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
  18 static struct kmem_cache *pgd_cache __ro_after_init;
  19
  20 pgd_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
  30 void 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
  38 void __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 }