1 /* 2 * linux/arch/arm/mm/pgd.c 3 * 4 * Copyright (C) 1998-2005 Russell King 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License version 2 as 8 * published by the Free Software Foundation. 9 */ 10 #include <linux/mm.h> 11 #include <linux/gfp.h> 12 #include <linux/highmem.h> 13 14 #include <asm/pgalloc.h> 15 #include <asm/page.h> 16 #include <asm/tlbflush.h> 17 18 #include "mm.h" 19 20 #define FIRST_KERNEL_PGD_NR (FIRST_USER_PGD_NR + USER_PTRS_PER_PGD) 21 22 /* 23 * need to get a 16k page for level 1 24 */ 25 pgd_t *get_pgd_slow(struct mm_struct *mm) 26 { 27 pgd_t *new_pgd, *init_pgd; 28 pmd_t *new_pmd, *init_pmd; 29 pte_t *new_pte, *init_pte; 30 31 new_pgd = (pgd_t *)__get_free_pages(GFP_KERNEL, 2); 32 if (!new_pgd) 33 goto no_pgd; 34 35 memset(new_pgd, 0, FIRST_KERNEL_PGD_NR * sizeof(pgd_t)); 36 37 /* 38 * Copy over the kernel and IO PGD entries 39 */ 40 init_pgd = pgd_offset_k(0); 41 memcpy(new_pgd + FIRST_KERNEL_PGD_NR, init_pgd + FIRST_KERNEL_PGD_NR, 42 (PTRS_PER_PGD - FIRST_KERNEL_PGD_NR) * sizeof(pgd_t)); 43 44 clean_dcache_area(new_pgd, PTRS_PER_PGD * sizeof(pgd_t)); 45 46 if (!vectors_high()) { 47 /* 48 * On ARM, first page must always be allocated since it 49 * contains the machine vectors. 50 */ 51 new_pmd = pmd_alloc(mm, new_pgd, 0); 52 if (!new_pmd) 53 goto no_pmd; 54 55 new_pte = pte_alloc_map(mm, new_pmd, 0); 56 if (!new_pte) 57 goto no_pte; 58 59 init_pmd = pmd_offset(init_pgd, 0); 60 init_pte = pte_offset_map_nested(init_pmd, 0); 61 set_pte_ext(new_pte, *init_pte, 0); 62 pte_unmap_nested(init_pte); 63 pte_unmap(new_pte); 64 } 65 66 return new_pgd; 67 68 no_pte: 69 pmd_free(mm, new_pmd); 70 no_pmd: 71 free_pages((unsigned long)new_pgd, 2); 72 no_pgd: 73 return NULL; 74 } 75 76 void free_pgd_slow(struct mm_struct *mm, pgd_t *pgd) 77 { 78 pmd_t *pmd; 79 pgtable_t pte; 80 81 if (!pgd) 82 return; 83 84 /* pgd is always present and good */ 85 pmd = pmd_off(pgd, 0); 86 if (pmd_none(*pmd)) 87 goto free; 88 if (pmd_bad(*pmd)) { 89 pmd_ERROR(*pmd); 90 pmd_clear(pmd); 91 goto free; 92 } 93 94 pte = pmd_pgtable(*pmd); 95 pmd_clear(pmd); 96 pte_free(mm, pte); 97 pmd_free(mm, pmd); 98 free: 99 free_pages((unsigned long) pgd, 2); 100 } 101