File: /usr/src/linux/arch/arm/mm/mm-armo.c
1 /*
2 * linux/arch/arm/mm/mm-armo.c
3 *
4 * Copyright (C) 1998-2000 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 * Page table sludge for older ARM processor architectures.
11 */
12 #include <linux/sched.h>
13 #include <linux/mm.h>
14 #include <linux/init.h>
15 #include <linux/bootmem.h>
16
17 #include <asm/pgtable.h>
18 #include <asm/pgalloc.h>
19 #include <asm/page.h>
20 #include <asm/arch/memory.h>
21
22 #include <asm/mach/map.h>
23
24 #define MEMC_TABLE_SIZE (256*sizeof(unsigned long))
25
26 kmem_cache_t *pte_cache, *pgd_cache;
27 int page_nr;
28
29 /*
30 * Allocate a page table. Note that we place the MEMC
31 * table before the page directory. This means we can
32 * easily get to both tightly-associated data structures
33 * with a single pointer.
34 */
35 static inline pgd_t *alloc_pgd_table(int priority)
36 {
37 void *pg2k = kmem_cache_alloc(pgd_cache, GFP_KERNEL);
38
39 if (pg2k)
40 pg2k += MEMC_TABLE_SIZE;
41
42 return (pgd_t *)pg2k;
43 }
44
45 void free_pgd_slow(pgd_t *pgd)
46 {
47 unsigned long tbl = (unsigned long)pgd;
48
49 /*
50 * CHECKME: are we leaking pte tables here???
51 */
52
53 tbl -= MEMC_TABLE_SIZE;
54
55 kmem_cache_free(pgd_cache, (void *)tbl);
56 }
57
58 pgd_t *get_pgd_slow(struct mm_struct *mm)
59 {
60 pgd_t *new_pgd, *init_pgd;
61 pmd_t *new_pmd, *init_pmd;
62 pte_t *new_pte, *init_pte;
63
64 new_pgd = alloc_pgd_table(GFP_KERNEL);
65 if (!new_pgd)
66 goto no_pgd;
67
68 /*
69 * This lock is here just to satisfy pmd_alloc and pte_lock
70 */
71 spin_lock(&mm->page_table_lock);
72
73 /*
74 * On ARM, first page must always be allocated since it contains
75 * the machine vectors.
76 */
77 new_pmd = pmd_alloc(mm, new_pgd, 0);
78 if (!new_pmd)
79 goto no_pmd;
80
81 new_pte = pte_alloc(mm, new_pmd, 0);
82 if (!new_pte)
83 goto no_pte;
84
85 init_pgd = pgd_offset_k(0);
86 init_pmd = pmd_offset(init_pgd, 0);
87 init_pte = pte_offset(init_pmd, 0);
88
89 set_pte(new_pte, *init_pte);
90
91 /*
92 * most of the page table entries are zeroed
93 * wne the table is created.
94 */
95 memcpy(new_pgd + USER_PTRS_PER_PGD, init_pgd + USER_PTRS_PER_PGD,
96 (PTRS_PER_PGD - USER_PTRS_PER_PGD) * sizeof(pgd_t));
97
98 spin_unlock(&mm->page_table_lock);
99
100 /* update MEMC tables */
101 cpu_memc_update_all(new_pgd);
102 return new_pgd;
103
104 no_pte:
105 spin_unlock(&mm->page_table_lock);
106 pmd_free(new_pmd);
107 free_pgd_slow(new_pgd);
108 return NULL;
109
110 no_pmd:
111 spin_unlock(&mm->page_table_lock);
112 free_pgd_slow(new_pgd);
113 return NULL;
114
115 no_pgd:
116 return NULL;
117 }
118
119 /*
120 * No special code is required here.
121 */
122 void setup_mm_for_reboot(char mode)
123 {
124 }
125
126 /*
127 * This contains the code to setup the memory map on an ARM2/ARM250/ARM3
128 * machine. This is both processor & architecture specific, and requires
129 * some more work to get it to fit into our separate processor and
130 * architecture structure.
131 */
132 void __init memtable_init(struct meminfo *mi)
133 {
134 pte_t *pte;
135 int i;
136
137 page_nr = max_low_pfn;
138
139 pte = alloc_bootmem_low_pages(PTRS_PER_PTE * sizeof(pte_t));
140 pte[0] = mk_pte_phys(PAGE_OFFSET + 491520, PAGE_READONLY);
141 pmd_populate(&init_mm, pmd_offset(swapper_pg_dir, 0), pte);
142
143 for (i = 1; i < PTRS_PER_PGD; i++)
144 pgd_val(swapper_pg_dir[i]) = 0;
145 }
146
147 void __init iotable_init(struct map_desc *io_desc)
148 {
149 /* nothing to do */
150 }
151
152 /*
153 * We never have holes in the memmap
154 */
155 void __init create_memmap_holes(struct meminfo *mi)
156 {
157 }
158
159 static void pte_cache_ctor(void *pte, kmem_cache_t *cache, unsigned long flags)
160 {
161 memzero(pte, sizeof(pte_t) * PTRS_PER_PTE);
162 }
163
164 static void pgd_cache_ctor(void *pte, kmem_cache_t *cache, unsigned long flags)
165 {
166 pgd_t *pgd = (pte + MEMC_TABLE_SIZE);
167
168 memzero(pgd, USER_PTRS_PER_PGD * sizeof(pgd_t));
169 }
170
171 void __init pgtable_cache_init(void)
172 {
173 pte_cache = kmem_cache_create("pte-cache",
174 sizeof(pte_t) * PTRS_PER_PTE,
175 0, 0, pte_cache_ctor, NULL);
176 if (!pte_cache)
177 BUG();
178
179 pgd_cache = kmem_cache_create("pgd-cache", MEMC_TABLE_SIZE +
180 sizeof(pgd_t) * PTRS_PER_PGD,
181 0, 0, pgd_cache_ctor, NULL);
182 if (!pgd_cache)
183 BUG();
184 }
185