1 /* 2 * Copyright (C) 2009 Wind River Systems Inc 3 * Implemented by fredrik.markstrom@gmail.com and ivarholmqvist@gmail.com 4 * 5 * This file is subject to the terms and conditions of the GNU General Public 6 * License. See the file "COPYING" in the main directory of this archive 7 * for more details. 8 */ 9 10 #include <linux/mm.h> 11 #include <linux/sched.h> 12 13 #include <asm/pgtable.h> 14 #include <asm/cpuinfo.h> 15 16 /* pteaddr: 17 * ptbase | vpn* | zero 18 * 31-22 | 21-2 | 1-0 19 * 20 * *vpn is preserved on double fault 21 * 22 * tlbacc: 23 * IG |*flags| pfn 24 * 31-25|24-20 | 19-0 25 * 26 * *crwxg 27 * 28 * tlbmisc: 29 * resv |way |rd | we|pid |dbl|bad|perm|d 30 * 31-24 |23-20 |19 | 20|17-4|3 |2 |1 |0 31 * 32 */ 33 34 /* 35 * Initialize a new pgd / pmd table with invalid pointers. 36 */ 37 static void pgd_init(pgd_t *pgd) 38 { 39 unsigned long *p = (unsigned long *) pgd; 40 int i; 41 42 for (i = 0; i < USER_PTRS_PER_PGD; i += 8) { 43 p[i + 0] = (unsigned long) invalid_pte_table; 44 p[i + 1] = (unsigned long) invalid_pte_table; 45 p[i + 2] = (unsigned long) invalid_pte_table; 46 p[i + 3] = (unsigned long) invalid_pte_table; 47 p[i + 4] = (unsigned long) invalid_pte_table; 48 p[i + 5] = (unsigned long) invalid_pte_table; 49 p[i + 6] = (unsigned long) invalid_pte_table; 50 p[i + 7] = (unsigned long) invalid_pte_table; 51 } 52 } 53 54 pgd_t *pgd_alloc(struct mm_struct *mm) 55 { 56 pgd_t *ret, *init; 57 58 ret = (pgd_t *) __get_free_pages(GFP_KERNEL, PGD_ORDER); 59 if (ret) { 60 init = pgd_offset(&init_mm, 0UL); 61 pgd_init(ret); 62 memcpy(ret + USER_PTRS_PER_PGD, init + USER_PTRS_PER_PGD, 63 (PTRS_PER_PGD - USER_PTRS_PER_PGD) * sizeof(pgd_t)); 64 } 65 66 return ret; 67 } 68 69 void __init pagetable_init(void) 70 { 71 /* Initialize the entire pgd. */ 72 pgd_init(swapper_pg_dir); 73 pgd_init(swapper_pg_dir + USER_PTRS_PER_PGD); 74 } 75