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
|
#include <kernel/paging.h>
#include <kernel/asm.h>
#include <kernel/vmem.h>
#include <kernel/pmem.h>
#include <kernel/panic.h>
#include <kernel/syscall.h>
#include <libk/io.h>
#include <libk/string.h>
static int paging_enabled = 0;
void paging_init(void) {
if (paging_enabled == 1)
return;
uintptr_t phys_pt = pfa_alloc(1);
map_page(phys_pt, PAGE_TMP_MAP, PD_PRES | PD_RW);
uintptr_t *pt = (uintptr_t*)PAGE_TMP_MAP;
for (uintptr_t i = KSTART; i < KEND; i += PAGE_SIZE)
pt[GET_PTX(GET_VADDR(i))] = i | PD_PRES;
unmap_page(PAGE_TMP_MAP);
uintptr_t phys_pd = pfa_alloc(1);
map_page(phys_pd, PAGE_TMP_MAP, PD_PRES | PD_RW);
uintptr_t *pd = (uintptr_t*)PAGE_TMP_MAP;
pd[GET_PDX(GET_VADDR(KSTART))] = phys_pt | PD_PRES | PD_RW;
pd[1023] = phys_pd | PD_PRES | PD_RW;
unmap_page(PAGE_TMP_MAP);
enable_paging(phys_pd);
paging_enabled = 1;
return;
}
void init_page_table(int pdindex, uint32_t flags) {
uintptr_t *pd = (uintptr_t*)PAGE_DIR_MAP;
if ((pd[pdindex] & PD_PRES) != 0)
return;
uintptr_t paddr = pfa_alloc(1);
pd[pdindex] = paddr | PD_PRES | PD_RW | flags;
uintptr_t *pt = ((uintptr_t*)PAGE_TAB_MAP) + (pdindex << 12);
pd[GET_PDX(pt)] = paddr | PD_PRES | PD_RW;
}
uintptr_t init_page_directory(void) {
uintptr_t ret = pfa_alloc(1);
map_page(ret, PAGE_TMP_MAP, PD_RW);
uintptr_t *new_pd = (uintptr_t*)PAGE_TMP_MAP;
uintptr_t *cur_pd = (uintptr_t*)PAGE_DIR_MAP;
int kernel_pdx = GET_PDX(GET_VADDR(KSTART));
new_pd[kernel_pdx] = cur_pd[kernel_pdx];
unmap_page(PAGE_TMP_MAP);
return ret;
}
void map_page(uintptr_t paddr, uintptr_t vaddr, uint32_t flags) {
paddr = PGROUNDDN(paddr);
vaddr = PGROUNDDN(vaddr);
int pdindex = GET_PDX(vaddr);
int ptindex = GET_PTX(vaddr);
uintptr_t *pd = (uintptr_t*)PAGE_DIR_MAP;
if ((pd[pdindex] & PD_PRES) == 0)
init_page_table(pdindex, 0);
uintptr_t *pt = (uintptr_t*)(PAGE_TAB_MAP + (pdindex << 12));
pt[ptindex] = paddr | PD_PRES | flags;
invlpg((void*)vaddr);
}
void unmap_page(uintptr_t vaddr) {
uintptr_t pdindex = GET_PDX(vaddr);
uintptr_t ptindex = GET_PTX(vaddr);
uintptr_t *pd = (uintptr_t*)PAGE_DIR_MAP;
if ((pd[pdindex] & PD_PRES) == 0)
return;
uintptr_t *pt = (uintptr_t*)(PAGE_TAB_MAP + (pdindex << 12));
pt[ptindex] = 0;
invlpg((void*)vaddr);
}
void page_fault_handler(struct isr_frame *frame) {
uintptr_t fault_addr;
__asm__ volatile("movl %%cr2, %0" : "=r"(fault_addr));
kprintf("Faulting address: %x\n", fault_addr);
panic("Page fault not operational");
switch (frame->isr_err) {
case 0:
//map_page((uintptr_t*)GET_VADDR(frame->cr3), pfa_alloc(), fault_addr, PD_PRES);
break;
case 1:
panic("Kernel process caused protection fault on read\n");
break;
case 2:
//map_page((uintptr_t*)GET_VADDR(frame->cr3), pfa_alloc(), fault_addr, PD_PRES | PD_RW);
break;
case 3:
panic("Kernel process caused protection fault on write\n");
break;
case 4:
//map_page((uintptr_t*)GET_VADDR(frame->cr3), pfa_alloc(), fault_addr, PD_PRES | PD_USR);
break;
case 5:
// TODO: instead of panicking, kill process
panic("User process caused protection fault on read\n");
break;
case 6:
//map_page((uintptr_t*)GET_VADDR(frame->cr3), pfa_alloc(), fault_addr, PD_PRES | PD_RW | PD_USR);
break;
case 7:
// TODO: see case 101
panic("USER process caused protection fault on write\n");
break;
default:
kprintf("Unknown paging error occured on address %x\n", fault_addr);
panic("Paging error");
break;
}
}
|
