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
|
#include <stddef.h>
#include "paging.h"
#include "kheap.h"
#include "../lib/lib.h"
#include "../graphics/graphics.h"
#include "../interrupts/interrupts.h"
vpage_dir_t *current_vpage_dir = NULL;
vpage_dir_t *root_vpage_dir = NULL;
//Assembly abstraction for more maintainable code
page_table_t *get_cr3() {
unsigned int cr3;
asm volatile ("movl %%cr3, %%eax" : "=a" (cr3));
return (page_table_t *) cr3;
}
unsigned int get_cr0() {
unsigned int cr0;
asm volatile ("movl %%cr0, %%eax" : "=a" (cr0));
return cr0;
}
void set_cr3(vpage_dir_t *dir) {
asm volatile ("movl %%eax, %%cr3"::"a" ((unsigned int) &dir->tables[0]));
}
void set_cr0(unsigned int new_cr0) {
asm volatile ("movl %%eax, %%cr0"::"a" (new_cr0));
}
void switch_vpage_dir(vpage_dir_t *dir) {
set_cr3(dir);
set_cr0(get_cr0() | 0x80000000);
}
vpage_dir_t *mk_vpage_dir() {
vpage_dir_t *dir = (vpage_dir_t *) kmalloc_a(sizeof(vpage_dir_t));
int i;
for (i = 0; i < 1024; i++)
dir->tables[i] = EMPTY_TAB;
return dir;
}
page_table_t *mk_vpage_table() {
page_table_t *tab = (page_table_t *) kmalloc_a(sizeof(page_table_t));
int i;
for (i = 0; i < 1024; i++) {
tab->pages[i].present = 0;
tab->pages[i].rw = 1;
}
return tab;
}
void vpage_map(vpage_dir_t *dir, unsigned int phys, unsigned int virt) {
short id = virt >> 22;
page_table_t *tab = mk_vpage_table();
dir->tables[id] = ((page_table_t *) ((unsigned int) tab | 3));
int i;
for (i = 0; i < 1024; i++) {
tab->pages[i].frame = phys >> 12;
tab->pages[i].present = 1;
phys += 4096;
}
}
void vpage_map_user(vpage_dir_t *dir, unsigned int phys, unsigned int virt) {
short id = virt >> 22;
page_table_t *tab = mk_vpage_table();
dir->tables[id] = ((page_table_t *) ((unsigned int) tab | 3 | 4));
int i;
for (i = 0; i < 1024; i++) {
tab->pages[i].frame = phys >> 12;
tab->pages[i].present = 1;
tab->pages[i].user = 1;
phys += 4096;
}
}
void vpage_fault(struct regs *r) {
asm volatile ("cli");
unsigned int no_page = r->err_code & 1;
unsigned int rw = r->err_code & 2;
unsigned int um = r->err_code & 4;
unsigned int re = r->err_code & 8;
unsigned int dc = r->err_code & 16;
if (dc) terminal_write_line(" (Instruction decode error) ");
if (!no_page) terminal_write_line(" (No page present) ");
if (um) terminal_write_line(" (in user mode) ");
if (rw) terminal_write_line(" (Write permissions) ");
if (re) terminal_write_line(" (RE) ");
terminal_write_line("\n");
}
void page_init() {
current_vpage_dir = mk_vpage_dir();
root_vpage_dir = current_vpage_dir;
unsigned int i;
for (i = 0; i < 0xF0000000; i += PAGE_S)
vpage_map(root_vpage_dir, i, i);
irq_install_handler(14, vpage_fault);
asm volatile ("cli");
switch_vpage_dir(root_vpage_dir);
}
void convert_vpage(vpage_dir_t *kdir) {
int i;
for (i = 0; i < 1024; i++) {
kdir->tables[i] = (page_table_t *) ((unsigned int) kdir->tables[i] | 4);
if (((unsigned int) kdir->tables[i]) & 1) {
int j;
for (j = 0; j < 1024; j++)
kdir->tables[i]->pages[j].user = 1;
}
}
}
void dump_page(vpage_dir_t *dir, unsigned int address) {
unsigned short id = address >> 22;
terminal_write_line(&"Index salt ="[(unsigned int) dir->tables[id]]);
}
vpage_dir_t *copy_user_dir(vpage_dir_t *dir) {
unsigned int i;
vpage_dir_t *copy = mk_vpage_dir();
memory_copy(copy, root_vpage_dir, sizeof(vpage_dir_t));
for (i = 0; i < 1024; i++) {
if (((unsigned int) dir->tables[i]) & 4) {
//vga_fmt("Found a user page at index %d\n", i);
page_table_t *tab = (page_table_t *) ((unsigned int) dir->tables[i] & 0xFFFFF000);
//vga_fmt("Table at address %X maps to %X\n", (unsigned int) tab, i << 22);
//vga_fmt("Virtually mapped from %X\n", tab->pages[0].frame << 12);
void *buffer = kmalloc_a(PAGE_S);
memory_copy(buffer, (void *) (tab->pages[0].frame << 12), PAGE_S);
vpage_map_user(copy, (unsigned int) buffer, (unsigned int) i << 22);
}
}
return copy;
}
|
