root/arch/arm/mm/pgd.c

DEFINITIONS

1. pgd_alloc
2. pgd_free

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *  linux/arch/arm/mm/pgd.c
   4  *
   5  *  Copyright (C) 1998-2005 Russell King
   6  */
   7 #include <linux/mm.h>
   8 #include <linux/gfp.h>
   9 #include <linux/highmem.h>
  10 #include <linux/slab.h>
  11 
  12 #include <asm/cp15.h>
  13 #include <asm/pgalloc.h>
  14 #include <asm/page.h>
  15 #include <asm/tlbflush.h>
  16 
  17 #include "mm.h"
  18 
  19 #ifdef CONFIG_ARM_LPAE
  20 #define __pgd_alloc()   kmalloc_array(PTRS_PER_PGD, sizeof(pgd_t), GFP_KERNEL)
  21 #define __pgd_free(pgd) kfree(pgd)
  22 #else
  23 #define __pgd_alloc()   (pgd_t *)__get_free_pages(GFP_KERNEL, 2)
  24 #define __pgd_free(pgd) free_pages((unsigned long)pgd, 2)
  25 #endif
  26 
  27 /*
  28  * need to get a 16k page for level 1
  29  */
  30 pgd_t *pgd_alloc(struct mm_struct *mm)
  31 {
  32         pgd_t *new_pgd, *init_pgd;
  33         pud_t *new_pud, *init_pud;
  34         pmd_t *new_pmd, *init_pmd;
  35         pte_t *new_pte, *init_pte;
  36 
  37         new_pgd = __pgd_alloc();
  38         if (!new_pgd)
  39                 goto no_pgd;
  40 
  41         memset(new_pgd, 0, USER_PTRS_PER_PGD * sizeof(pgd_t));
  42 
  43         /*
  44          * Copy over the kernel and IO PGD entries
  45          */
  46         init_pgd = pgd_offset_k(0);
  47         memcpy(new_pgd + USER_PTRS_PER_PGD, init_pgd + USER_PTRS_PER_PGD,
  48                        (PTRS_PER_PGD - USER_PTRS_PER_PGD) * sizeof(pgd_t));
  49 
  50         clean_dcache_area(new_pgd, PTRS_PER_PGD * sizeof(pgd_t));
  51 
  52 #ifdef CONFIG_ARM_LPAE
  53         /*
  54          * Allocate PMD table for modules and pkmap mappings.
  55          */
  56         new_pud = pud_alloc(mm, new_pgd + pgd_index(MODULES_VADDR),
  57                             MODULES_VADDR);
  58         if (!new_pud)
  59                 goto no_pud;
  60 
  61         new_pmd = pmd_alloc(mm, new_pud, 0);
  62         if (!new_pmd)
  63                 goto no_pmd;
  64 #endif
  65 
  66         if (!vectors_high()) {
  67                 /*
  68                  * On ARM, first page must always be allocated since it
  69                  * contains the machine vectors. The vectors are always high
  70                  * with LPAE.
  71                  */
  72                 new_pud = pud_alloc(mm, new_pgd, 0);
  73                 if (!new_pud)
  74                         goto no_pud;
  75 
  76                 new_pmd = pmd_alloc(mm, new_pud, 0);
  77                 if (!new_pmd)
  78                         goto no_pmd;
  79 
  80                 new_pte = pte_alloc_map(mm, new_pmd, 0);
  81                 if (!new_pte)
  82                         goto no_pte;
  83 
  84 #ifndef CONFIG_ARM_LPAE
  85                 /*
  86                  * Modify the PTE pointer to have the correct domain.  This
  87                  * needs to be the vectors domain to avoid the low vectors
  88                  * being unmapped.
  89                  */
  90                 pmd_val(*new_pmd) &= ~PMD_DOMAIN_MASK;
  91                 pmd_val(*new_pmd) |= PMD_DOMAIN(DOMAIN_VECTORS);
  92 #endif
  93 
  94                 init_pud = pud_offset(init_pgd, 0);
  95                 init_pmd = pmd_offset(init_pud, 0);
  96                 init_pte = pte_offset_map(init_pmd, 0);
  97                 set_pte_ext(new_pte + 0, init_pte[0], 0);
  98                 set_pte_ext(new_pte + 1, init_pte[1], 0);
  99                 pte_unmap(init_pte);
 100                 pte_unmap(new_pte);
 101         }
 102 
 103         return new_pgd;
 104 
 105 no_pte:
 106         pmd_free(mm, new_pmd);
 107         mm_dec_nr_pmds(mm);
 108 no_pmd:
 109         pud_free(mm, new_pud);
 110 no_pud:
 111         __pgd_free(new_pgd);
 112 no_pgd:
 113         return NULL;
 114 }
 115 
 116 void pgd_free(struct mm_struct *mm, pgd_t *pgd_base)
 117 {
 118         pgd_t *pgd;
 119         pud_t *pud;
 120         pmd_t *pmd;
 121         pgtable_t pte;
 122 
 123         if (!pgd_base)
 124                 return;
 125 
 126         pgd = pgd_base + pgd_index(0);
 127         if (pgd_none_or_clear_bad(pgd))
 128                 goto no_pgd;
 129 
 130         pud = pud_offset(pgd, 0);
 131         if (pud_none_or_clear_bad(pud))
 132                 goto no_pud;
 133 
 134         pmd = pmd_offset(pud, 0);
 135         if (pmd_none_or_clear_bad(pmd))
 136                 goto no_pmd;
 137 
 138         pte = pmd_pgtable(*pmd);
 139         pmd_clear(pmd);
 140         pte_free(mm, pte);
 141         mm_dec_nr_ptes(mm);
 142 no_pmd:
 143         pud_clear(pud);
 144         pmd_free(mm, pmd);
 145         mm_dec_nr_pmds(mm);
 146 no_pud:
 147         pgd_clear(pgd);
 148         pud_free(mm, pud);
 149 no_pgd:
 150 #ifdef CONFIG_ARM_LPAE
 151         /*
 152          * Free modules/pkmap or identity pmd tables.
 153          */
 154         for (pgd = pgd_base; pgd < pgd_base + PTRS_PER_PGD; pgd++) {
 155                 if (pgd_none_or_clear_bad(pgd))
 156                         continue;
 157                 if (pgd_val(*pgd) & L_PGD_SWAPPER)
 158                         continue;
 159                 pud = pud_offset(pgd, 0);
 160                 if (pud_none_or_clear_bad(pud))
 161                         continue;
 162                 pmd = pmd_offset(pud, 0);
 163                 pud_clear(pud);
 164                 pmd_free(mm, pmd);
 165                 mm_dec_nr_pmds(mm);
 166                 pgd_clear(pgd);
 167                 pud_free(mm, pud);
 168         }
 169 #endif
 170         __pgd_free(pgd_base);
 171 }