arch/arm/mm/pgd.c

   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         p4d_t *new_p4d, *init_p4d;
  34         pud_t *new_pud, *init_pud;
  35         pmd_t *new_pmd, *init_pmd;
  36         pte_t *new_pte, *init_pte;
  37
  38         new_pgd = __pgd_alloc();
  39         if (!new_pgd)
  40                 goto no_pgd;
  41
  42         memset(new_pgd, 0, USER_PTRS_PER_PGD * sizeof(pgd_t));
  43
  44         /*
  45          * Copy over the kernel and IO PGD entries
  46          */
  47         init_pgd = pgd_offset_k(0);
  48         memcpy(new_pgd + USER_PTRS_PER_PGD, init_pgd + USER_PTRS_PER_PGD,
  49                        (PTRS_PER_PGD - USER_PTRS_PER_PGD) * sizeof(pgd_t));
  50
  51         clean_dcache_area(new_pgd, PTRS_PER_PGD * sizeof(pgd_t));
  52
  53 #ifdef CONFIG_ARM_LPAE
  54         /*
  55          * Allocate PMD table for modules and pkmap mappings.
  56          */
  57         new_p4d = p4d_alloc(mm, new_pgd + pgd_index(MODULES_VADDR),
  58                             MODULES_VADDR);
  59         if (!new_p4d)
  60                 goto no_p4d;
  61
  62         new_pud = pud_alloc(mm, new_p4d, MODULES_VADDR);
  63         if (!new_pud)
  64                 goto no_pud;
  65
  66         new_pmd = pmd_alloc(mm, new_pud, 0);
  67         if (!new_pmd)
  68                 goto no_pmd;
  69 #ifdef CONFIG_KASAN
  70         /*
  71          * Copy PMD table for KASAN shadow mappings.
  72          */
  73         init_pgd = pgd_offset_k(TASK_SIZE);
  74         init_p4d = p4d_offset(init_pgd, TASK_SIZE);
  75         init_pud = pud_offset(init_p4d, TASK_SIZE);
  76         init_pmd = pmd_offset(init_pud, TASK_SIZE);
  77         new_pmd = pmd_offset(new_pud, TASK_SIZE);
  78         memcpy(new_pmd, init_pmd,
  79                (pmd_index(MODULES_VADDR) - pmd_index(TASK_SIZE))
  80                * sizeof(pmd_t));
  81         clean_dcache_area(new_pmd, PTRS_PER_PMD * sizeof(pmd_t));
  82 #endif /* CONFIG_KASAN */
  83 #endif /* CONFIG_LPAE */
  84
  85         if (!vectors_high()) {
  86                 /*
  87                  * On ARM, first page must always be allocated since it
  88                  * contains the machine vectors. The vectors are always high
  89                  * with LPAE.
  90                  */
  91                 new_p4d = p4d_alloc(mm, new_pgd, 0);
  92                 if (!new_p4d)
  93                         goto no_p4d;
  94
  95                 new_pud = pud_alloc(mm, new_p4d, 0);
  96                 if (!new_pud)
  97                         goto no_pud;
  98
  99                 new_pmd = pmd_alloc(mm, new_pud, 0);
 100                 if (!new_pmd)
 101                         goto no_pmd;
 102
 103                 new_pte = pte_alloc_map(mm, new_pmd, 0);
 104                 if (!new_pte)
 105                         goto no_pte;
 106
 107 #ifndef CONFIG_ARM_LPAE
 108                 /*
 109                  * Modify the PTE pointer to have the correct domain.  This
 110                  * needs to be the vectors domain to avoid the low vectors
 111                  * being unmapped.
 112                  */
 113                 pmd_val(*new_pmd) &= ~PMD_DOMAIN_MASK;
 114                 pmd_val(*new_pmd) |= PMD_DOMAIN(DOMAIN_VECTORS);
 115 #endif
 116
 117                 init_p4d = p4d_offset(init_pgd, 0);
 118                 init_pud = pud_offset(init_p4d, 0);
 119                 init_pmd = pmd_offset(init_pud, 0);
 120                 init_pte = pte_offset_map(init_pmd, 0);
 121                 set_pte_ext(new_pte + 0, init_pte[0], 0);
 122                 set_pte_ext(new_pte + 1, init_pte[1], 0);
 123                 pte_unmap(init_pte);
 124                 pte_unmap(new_pte);
 125         }
 126
 127         return new_pgd;
 128
 129 no_pte:
 130         pmd_free(mm, new_pmd);
 131         mm_dec_nr_pmds(mm);
 132 no_pmd:
 133         pud_free(mm, new_pud);
 134 no_pud:
 135         p4d_free(mm, new_p4d);
 136 no_p4d:
 137         __pgd_free(new_pgd);
 138 no_pgd:
 139         return NULL;
 140 }
 141
 142 void pgd_free(struct mm_struct *mm, pgd_t *pgd_base)
 143 {
 144         pgd_t *pgd;
 145         p4d_t *p4d;
 146         pud_t *pud;
 147         pmd_t *pmd;
 148         pgtable_t pte;
 149
 150         if (!pgd_base)
 151                 return;
 152
 153         pgd = pgd_base + pgd_index(0);
 154         if (pgd_none_or_clear_bad(pgd))
 155                 goto no_pgd;
 156
 157         p4d = p4d_offset(pgd, 0);
 158         if (p4d_none_or_clear_bad(p4d))
 159                 goto no_p4d;
 160
 161         pud = pud_offset(p4d, 0);
 162         if (pud_none_or_clear_bad(pud))
 163                 goto no_pud;
 164
 165         pmd = pmd_offset(pud, 0);
 166         if (pmd_none_or_clear_bad(pmd))
 167                 goto no_pmd;
 168
 169         pte = pmd_pgtable(*pmd);
 170         pmd_clear(pmd);
 171         pte_free(mm, pte);
 172         mm_dec_nr_ptes(mm);
 173 no_pmd:
 174         pud_clear(pud);
 175         pmd_free(mm, pmd);
 176         mm_dec_nr_pmds(mm);
 177 no_pud:
 178         p4d_clear(p4d);
 179         pud_free(mm, pud);
 180 no_p4d:
 181         pgd_clear(pgd);
 182         p4d_free(mm, p4d);
 183 no_pgd:
 184 #ifdef CONFIG_ARM_LPAE
 185         /*
 186          * Free modules/pkmap or identity pmd tables.
 187          */
 188         for (pgd = pgd_base; pgd < pgd_base + PTRS_PER_PGD; pgd++) {
 189                 if (pgd_none_or_clear_bad(pgd))
 190                         continue;
 191                 if (pgd_val(*pgd) & L_PGD_SWAPPER)
 192                         continue;
 193                 p4d = p4d_offset(pgd, 0);
 194                 if (p4d_none_or_clear_bad(p4d))
 195                         continue;
 196                 pud = pud_offset(p4d, 0);
 197                 if (pud_none_or_clear_bad(pud))
 198                         continue;
 199                 pmd = pmd_offset(pud, 0);
 200                 pud_clear(pud);
 201                 pmd_free(mm, pmd);
 202                 mm_dec_nr_pmds(mm);
 203                 p4d_clear(p4d);
 204                 pud_free(mm, pud);
 205                 mm_dec_nr_puds(mm);
 206                 pgd_clear(pgd);
 207                 p4d_free(mm, p4d);
 208         }
 209 #endif
 210         __pgd_free(pgd_base);
 211 }