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/cpuinfo.h>
14 
15 /* pteaddr:
16  *   ptbase | vpn* | zero
17  *   31-22  | 21-2 | 1-0
18  *
19  *   *vpn is preserved on double fault
20  *
21  * tlbacc:
22  *   IG   |*flags| pfn
23  *   31-25|24-20 | 19-0
24  *
25  *   *crwxg
26  *
27  * tlbmisc:
28  *   resv  |way   |rd | we|pid |dbl|bad|perm|d
29  *   31-24 |23-20 |19 | 20|17-4|3  |2  |1   |0
30  *
31  */
32 
33 /*
34  * Initialize a new pgd / pmd table with invalid pointers.
35  */
pgd_init(pgd_t * pgd)36 static void pgd_init(pgd_t *pgd)
37 {
38 	unsigned long *p = (unsigned long *) pgd;
39 	int i;
40 
41 	for (i = 0; i < USER_PTRS_PER_PGD; i += 8) {
42 		p[i + 0] = (unsigned long) invalid_pte_table;
43 		p[i + 1] = (unsigned long) invalid_pte_table;
44 		p[i + 2] = (unsigned long) invalid_pte_table;
45 		p[i + 3] = (unsigned long) invalid_pte_table;
46 		p[i + 4] = (unsigned long) invalid_pte_table;
47 		p[i + 5] = (unsigned long) invalid_pte_table;
48 		p[i + 6] = (unsigned long) invalid_pte_table;
49 		p[i + 7] = (unsigned long) invalid_pte_table;
50 	}
51 }
52 
pgd_alloc(struct mm_struct * mm)53 pgd_t *pgd_alloc(struct mm_struct *mm)
54 {
55 	pgd_t *ret, *init;
56 
57 	ret = (pgd_t *) __get_free_pages(GFP_KERNEL, PGD_ORDER);
58 	if (ret) {
59 		init = pgd_offset(&init_mm, 0UL);
60 		pgd_init(ret);
61 		memcpy(ret + USER_PTRS_PER_PGD, init + USER_PTRS_PER_PGD,
62 		       (PTRS_PER_PGD - USER_PTRS_PER_PGD) * sizeof(pgd_t));
63 	}
64 
65 	return ret;
66 }
67 
pagetable_init(void)68 void __init pagetable_init(void)
69 {
70 	/* Initialize the entire pgd.  */
71 	pgd_init(swapper_pg_dir);
72 	pgd_init(swapper_pg_dir + USER_PTRS_PER_PGD);
73 }
74