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/highmem.h> 12 13 #include <asm/pgalloc.h> 14 #include <asm/page.h> 15 #include <asm/tlbflush.h> 16 17 #include "mm.h" 18 19 #define FIRST_KERNEL_PGD_NR (FIRST_USER_PGD_NR + USER_PTRS_PER_PGD) 20 21 /* 22 * need to get a 16k page for level 1 23 */ 24 pgd_t *get_pgd_slow(struct mm_struct *mm) 25 { 26 pgd_t *new_pgd, *init_pgd; 27 pmd_t *new_pmd, *init_pmd; 28 pte_t *new_pte, *init_pte; 29 30 new_pgd = (pgd_t *)__get_free_pages(GFP_KERNEL, 2); 31 if (!new_pgd) 32 goto no_pgd; 33 34 memzero(new_pgd, FIRST_KERNEL_PGD_NR * sizeof(pgd_t)); 35 36 /* 37 * Copy over the kernel and IO PGD entries 38 */ 39 init_pgd = pgd_offset_k(0); 40 memcpy(new_pgd + FIRST_KERNEL_PGD_NR, init_pgd + FIRST_KERNEL_PGD_NR, 41 (PTRS_PER_PGD - FIRST_KERNEL_PGD_NR) * sizeof(pgd_t)); 42 43 clean_dcache_area(new_pgd, PTRS_PER_PGD * sizeof(pgd_t)); 44 45 if (!vectors_high()) { 46 /* 47 * On ARM, first page must always be allocated since it 48 * contains the machine vectors. 49 */ 50 new_pmd = pmd_alloc(mm, new_pgd, 0); 51 if (!new_pmd) 52 goto no_pmd; 53 54 new_pte = pte_alloc_map(mm, new_pmd, 0); 55 if (!new_pte) 56 goto no_pte; 57 58 init_pmd = pmd_offset(init_pgd, 0); 59 init_pte = pte_offset_map_nested(init_pmd, 0); 60 set_pte_ext(new_pte, *init_pte, 0); 61 pte_unmap_nested(init_pte); 62 pte_unmap(new_pte); 63 } 64 65 return new_pgd; 66 67 no_pte: 68 pmd_free(new_pmd); 69 no_pmd: 70 free_pages((unsigned long)new_pgd, 2); 71 no_pgd: 72 return NULL; 73 } 74 75 void free_pgd_slow(pgd_t *pgd) 76 { 77 pmd_t *pmd; 78 struct page *pte; 79 80 if (!pgd) 81 return; 82 83 /* pgd is always present and good */ 84 pmd = pmd_off(pgd, 0); 85 if (pmd_none(*pmd)) 86 goto free; 87 if (pmd_bad(*pmd)) { 88 pmd_ERROR(*pmd); 89 pmd_clear(pmd); 90 goto free; 91 } 92 93 pte = pmd_page(*pmd); 94 pmd_clear(pmd); 95 dec_zone_page_state(virt_to_page((unsigned long *)pgd), NR_PAGETABLE); 96 pte_lock_deinit(pte); 97 pte_free(pte); 98 pmd_free(pmd); 99 free: 100 free_pages((unsigned long) pgd, 2); 101 } 102