1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
|
/*
* linux/arch/arm26/mm/memc.c
*
* Copyright (C) 1998-2000 Russell King
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* Page table sludge for older ARM processor architectures.
*/
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/init.h>
#include <linux/bootmem.h>
#include <asm/pgtable.h>
#include <asm/pgalloc.h>
#include <asm/page.h>
#include <asm/memory.h>
#include <asm/hardware.h>
#include <asm/map.h>
#define MEMC_TABLE_SIZE (256*sizeof(unsigned long))
kmem_cache_t *pte_cache, *pgd_cache;
int page_nr;
/*
* Allocate space for a page table and a MEMC table.
* Note that we place the MEMC
* table before the page directory. This means we can
* easily get to both tightly-associated data structures
* with a single pointer.
*/
static inline pgd_t *alloc_pgd_table(void)
{
void *pg2k = kmem_cache_alloc(pgd_cache, GFP_KERNEL);
if (pg2k)
pg2k += MEMC_TABLE_SIZE;
return (pgd_t *)pg2k;
}
/*
* Free a page table. this function is the counterpart to get_pgd_slow
* below, not alloc_pgd_table above.
*/
void free_pgd_slow(pgd_t *pgd)
{
unsigned long tbl = (unsigned long)pgd;
tbl -= MEMC_TABLE_SIZE;
kmem_cache_free(pgd_cache, (void *)tbl);
}
/*
* Allocate a new pgd and fill it in ready for use
*
* A new tasks pgd is completely empty (all pages !present) except for:
*
* o The machine vectors at virtual address 0x0
* o The vmalloc region at the top of address space
*
*/
#define FIRST_KERNEL_PGD_NR (FIRST_USER_PGD_NR + USER_PTRS_PER_PGD)
pgd_t *get_pgd_slow(struct mm_struct *mm)
{
pgd_t *new_pgd, *init_pgd;
pmd_t *new_pmd, *init_pmd;
pte_t *new_pte, *init_pte;
new_pgd = alloc_pgd_table();
if (!new_pgd)
goto no_pgd;
/*
* This lock is here just to satisfy pmd_alloc and pte_lock
* FIXME: I bet we could avoid taking it pretty much altogether
*/
spin_lock(&mm->page_table_lock);
/*
* On ARM, first page must always be allocated since it contains
* the machine vectors.
*/
new_pmd = pmd_alloc(mm, new_pgd, 0);
if (!new_pmd)
goto no_pmd;
new_pte = pte_alloc_map(mm, new_pmd, 0);
if (!new_pte)
goto no_pte;
init_pgd = pgd_offset(&init_mm, 0);
init_pmd = pmd_offset(init_pgd, 0);
init_pte = pte_offset(init_pmd, 0);
set_pte(new_pte, *init_pte);
pte_unmap(new_pte);
/*
* the page table entries are zeroed
* when the table is created. (see the cache_ctor functions below)
* Now we need to plonk the kernel (vmalloc) area at the end of
* the address space. We copy this from the init thread, just like
* the init_pte we copied above...
*/
memcpy(new_pgd + FIRST_KERNEL_PGD_NR, init_pgd + FIRST_KERNEL_PGD_NR,
(PTRS_PER_PGD - FIRST_KERNEL_PGD_NR) * sizeof(pgd_t));
spin_unlock(&mm->page_table_lock);
/* update MEMC tables */
cpu_memc_update_all(new_pgd);
return new_pgd;
no_pte:
spin_unlock(&mm->page_table_lock);
pmd_free(new_pmd);
free_pgd_slow(new_pgd);
return NULL;
no_pmd:
spin_unlock(&mm->page_table_lock);
free_pgd_slow(new_pgd);
return NULL;
no_pgd:
return NULL;
}
/*
* No special code is required here.
*/
void setup_mm_for_reboot(char mode)
{
}
/*
* This contains the code to setup the memory map on an ARM2/ARM250/ARM3
* o swapper_pg_dir = 0x0207d000
* o kernel proper starts at 0x0208000
* o create (allocate) a pte to contain the machine vectors
* o populate the pte (points to 0x02078000) (FIXME - is it zeroed?)
* o populate the init tasks page directory (pgd) with the new pte
* o zero the rest of the init tasks pgdir (FIXME - what about vmalloc?!)
*/
void __init memtable_init(struct meminfo *mi)
{
pte_t *pte;
int i;
page_nr = max_low_pfn;
pte = alloc_bootmem_low_pages(PTRS_PER_PTE * sizeof(pte_t));
pte[0] = mk_pte_phys(PAGE_OFFSET + SCREEN_SIZE, PAGE_READONLY);
pmd_populate(&init_mm, pmd_offset(swapper_pg_dir, 0), pte);
for (i = 1; i < PTRS_PER_PGD; i++)
pgd_val(swapper_pg_dir[i]) = 0;
}
void __init iotable_init(struct map_desc *io_desc)
{
/* nothing to do */
}
/*
* We never have holes in the memmap
*/
void __init create_memmap_holes(struct meminfo *mi)
{
}
static void pte_cache_ctor(void *pte, kmem_cache_t *cache, unsigned long flags)
{
memzero(pte, sizeof(pte_t) * PTRS_PER_PTE);
}
static void pgd_cache_ctor(void *pgd, kmem_cache_t *cache, unsigned long flags)
{
memzero(pgd + MEMC_TABLE_SIZE, USER_PTRS_PER_PGD * sizeof(pgd_t));
}
void __init pgtable_cache_init(void)
{
pte_cache = kmem_cache_create("pte-cache",
sizeof(pte_t) * PTRS_PER_PTE,
0, 0, pte_cache_ctor, NULL);
if (!pte_cache)
BUG();
pgd_cache = kmem_cache_create("pgd-cache", MEMC_TABLE_SIZE +
sizeof(pgd_t) * PTRS_PER_PGD,
0, 0, pgd_cache_ctor, NULL);
if (!pgd_cache)
BUG();
}
|
