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 static bool pgdir_is_page_size(void)
  21 {
  22         if (PGD_SIZE == PAGE_SIZE)
  23                 return true;
  24         if (CONFIG_PGTABLE_LEVELS == 4)
  25                 return !pgtable_l4_enabled();
  26         if (CONFIG_PGTABLE_LEVELS == 5)
  27                 return !pgtable_l5_enabled();
  28         return false;
  29 }
  30
  31 pgd_t *pgd_alloc(struct mm_struct *mm)
  32 {
  33         gfp_t gfp = GFP_PGTABLE_USER;
  34
  35         if (pgdir_is_page_size())
  36                 return (pgd_t *)__get_free_page(gfp);
  37         else
  38                 return kmem_cache_alloc(pgd_cache, gfp);
  39 }
  40
  41 void pgd_free(struct mm_struct *mm, pgd_t *pgd)
  42 {
  43         if (pgdir_is_page_size())
  44                 free_page((unsigned long)pgd);
  45         else
  46                 kmem_cache_free(pgd_cache, pgd);
  47 }
  48
  49 void __init pgtable_cache_init(void)
  50 {
  51         if (pgdir_is_page_size())
  52                 return;
  53
  54 #ifdef CONFIG_ARM64_PA_BITS_52
  55         /*
  56          * With 52-bit physical addresses, the architecture requires the
  57          * top-level table to be aligned to at least 64 bytes.
  58          */
  59         BUILD_BUG_ON(PGD_SIZE < 64);
  60 #endif
  61
  62         /*
  63          * Naturally aligned pgds required by the architecture.
  64          */
  65         pgd_cache = kmem_cache_create("pgd_cache", PGD_SIZE, PGD_SIZE,
  66                                       SLAB_PANIC, NULL);
  67 }