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1da177e4 LT |
1 | /* |
2 | * linux/arch/arm26/mm/memc.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/memory.h> | |
21 | #include <asm/hardware.h> | |
22 | ||
23 | #include <asm/map.h> | |
24 | ||
25 | #define MEMC_TABLE_SIZE (256*sizeof(unsigned long)) | |
26 | ||
e18b890b | 27 | struct kmem_cache *pte_cache, *pgd_cache; |
1da177e4 LT |
28 | int page_nr; |
29 | ||
30 | /* | |
31 | * Allocate space for a page table and a MEMC table. | |
32 | * Note that we place the MEMC | |
33 | * table before the page directory. This means we can | |
34 | * easily get to both tightly-associated data structures | |
35 | * with a single pointer. | |
36 | */ | |
37 | static inline pgd_t *alloc_pgd_table(void) | |
38 | { | |
39 | void *pg2k = kmem_cache_alloc(pgd_cache, GFP_KERNEL); | |
40 | ||
41 | if (pg2k) | |
42 | pg2k += MEMC_TABLE_SIZE; | |
43 | ||
44 | return (pgd_t *)pg2k; | |
45 | } | |
46 | ||
47 | /* | |
48 | * Free a page table. this function is the counterpart to get_pgd_slow | |
49 | * below, not alloc_pgd_table above. | |
50 | */ | |
51 | void free_pgd_slow(pgd_t *pgd) | |
52 | { | |
53 | unsigned long tbl = (unsigned long)pgd; | |
54 | ||
55 | tbl -= MEMC_TABLE_SIZE; | |
56 | ||
57 | kmem_cache_free(pgd_cache, (void *)tbl); | |
58 | } | |
59 | ||
60 | /* | |
61 | * Allocate a new pgd and fill it in ready for use | |
62 | * | |
63 | * A new tasks pgd is completely empty (all pages !present) except for: | |
64 | * | |
65 | * o The machine vectors at virtual address 0x0 | |
66 | * o The vmalloc region at the top of address space | |
67 | * | |
68 | */ | |
69 | #define FIRST_KERNEL_PGD_NR (FIRST_USER_PGD_NR + USER_PTRS_PER_PGD) | |
70 | ||
71 | pgd_t *get_pgd_slow(struct mm_struct *mm) | |
72 | { | |
73 | pgd_t *new_pgd, *init_pgd; | |
74 | pmd_t *new_pmd, *init_pmd; | |
75 | pte_t *new_pte, *init_pte; | |
76 | ||
77 | new_pgd = alloc_pgd_table(); | |
78 | if (!new_pgd) | |
79 | goto no_pgd; | |
80 | ||
1da177e4 LT |
81 | /* |
82 | * On ARM, first page must always be allocated since it contains | |
83 | * the machine vectors. | |
84 | */ | |
85 | new_pmd = pmd_alloc(mm, new_pgd, 0); | |
86 | if (!new_pmd) | |
87 | goto no_pmd; | |
88 | ||
872fec16 | 89 | new_pte = pte_alloc_map(mm, new_pmd, 0); |
1da177e4 LT |
90 | if (!new_pte) |
91 | goto no_pte; | |
92 | ||
93 | init_pgd = pgd_offset(&init_mm, 0); | |
94 | init_pmd = pmd_offset(init_pgd, 0); | |
95 | init_pte = pte_offset(init_pmd, 0); | |
96 | ||
97 | set_pte(new_pte, *init_pte); | |
872fec16 | 98 | pte_unmap(new_pte); |
1da177e4 LT |
99 | |
100 | /* | |
101 | * the page table entries are zeroed | |
102 | * when the table is created. (see the cache_ctor functions below) | |
103 | * Now we need to plonk the kernel (vmalloc) area at the end of | |
104 | * the address space. We copy this from the init thread, just like | |
105 | * the init_pte we copied above... | |
106 | */ | |
107 | memcpy(new_pgd + FIRST_KERNEL_PGD_NR, init_pgd + FIRST_KERNEL_PGD_NR, | |
108 | (PTRS_PER_PGD - FIRST_KERNEL_PGD_NR) * sizeof(pgd_t)); | |
109 | ||
1da177e4 LT |
110 | /* update MEMC tables */ |
111 | cpu_memc_update_all(new_pgd); | |
112 | return new_pgd; | |
113 | ||
114 | no_pte: | |
1da177e4 | 115 | pmd_free(new_pmd); |
1da177e4 | 116 | no_pmd: |
1da177e4 | 117 | free_pgd_slow(new_pgd); |
1da177e4 LT |
118 | no_pgd: |
119 | return NULL; | |
120 | } | |
121 | ||
122 | /* | |
123 | * No special code is required here. | |
124 | */ | |
125 | void setup_mm_for_reboot(char mode) | |
126 | { | |
127 | } | |
128 | ||
129 | /* | |
130 | * This contains the code to setup the memory map on an ARM2/ARM250/ARM3 | |
131 | * o swapper_pg_dir = 0x0207d000 | |
132 | * o kernel proper starts at 0x0208000 | |
133 | * o create (allocate) a pte to contain the machine vectors | |
134 | * o populate the pte (points to 0x02078000) (FIXME - is it zeroed?) | |
135 | * o populate the init tasks page directory (pgd) with the new pte | |
136 | * o zero the rest of the init tasks pgdir (FIXME - what about vmalloc?!) | |
137 | */ | |
138 | void __init memtable_init(struct meminfo *mi) | |
139 | { | |
140 | pte_t *pte; | |
141 | int i; | |
142 | ||
143 | page_nr = max_low_pfn; | |
144 | ||
145 | pte = alloc_bootmem_low_pages(PTRS_PER_PTE * sizeof(pte_t)); | |
146 | pte[0] = mk_pte_phys(PAGE_OFFSET + SCREEN_SIZE, PAGE_READONLY); | |
147 | pmd_populate(&init_mm, pmd_offset(swapper_pg_dir, 0), pte); | |
148 | ||
149 | for (i = 1; i < PTRS_PER_PGD; i++) | |
150 | pgd_val(swapper_pg_dir[i]) = 0; | |
151 | } | |
152 | ||
153 | void __init iotable_init(struct map_desc *io_desc) | |
154 | { | |
155 | /* nothing to do */ | |
156 | } | |
157 | ||
158 | /* | |
159 | * We never have holes in the memmap | |
160 | */ | |
161 | void __init create_memmap_holes(struct meminfo *mi) | |
162 | { | |
163 | } | |
164 | ||
e18b890b | 165 | static void pte_cache_ctor(void *pte, struct kmem_cache *cache, unsigned long flags) |
1da177e4 LT |
166 | { |
167 | memzero(pte, sizeof(pte_t) * PTRS_PER_PTE); | |
168 | } | |
169 | ||
e18b890b | 170 | static void pgd_cache_ctor(void *pgd, struct kmem_cache *cache, unsigned long flags) |
1da177e4 LT |
171 | { |
172 | memzero(pgd + MEMC_TABLE_SIZE, USER_PTRS_PER_PGD * sizeof(pgd_t)); | |
173 | } | |
174 | ||
175 | void __init pgtable_cache_init(void) | |
176 | { | |
177 | pte_cache = kmem_cache_create("pte-cache", | |
178 | sizeof(pte_t) * PTRS_PER_PTE, | |
179 | 0, 0, pte_cache_ctor, NULL); | |
180 | if (!pte_cache) | |
181 | BUG(); | |
182 | ||
183 | pgd_cache = kmem_cache_create("pgd-cache", MEMC_TABLE_SIZE + | |
184 | sizeof(pgd_t) * PTRS_PER_PGD, | |
185 | 0, 0, pgd_cache_ctor, NULL); | |
186 | if (!pgd_cache) | |
187 | BUG(); | |
188 | } |