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
|
/*
* linux/arch/i386/mm/fault.c
*
* Copyright (C) 1995 Linus Torvalds
*/
#include <linux/config.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/head.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/ptrace.h>
#include <linux/mman.h>
#include <linux/mm.h>
#include <asm/system.h>
#include <asm/segment.h>
#include <asm/pgtable.h>
extern void die_if_kernel(char *,struct pt_regs *,long);
/*
* This routine handles page faults. It determines the address,
* and the problem, and then passes it off to one of the appropriate
* routines.
*
* error_code:
* bit 0 == 0 means no page found, 1 means protection fault
* bit 1 == 0 means read, 1 means write
* bit 2 == 0 means kernel, 1 means user-mode
*/
asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long error_code)
{
struct vm_area_struct * vma;
unsigned long address;
unsigned long page;
/* get the address */
__asm__("movl %%cr2,%0":"=r" (address));
vma = find_vma(current, address);
if (!vma)
goto bad_area;
if (vma->vm_start <= address)
goto good_area;
if (!(vma->vm_flags & VM_GROWSDOWN))
goto bad_area;
if (vma->vm_end - address > current->rlim[RLIMIT_STACK].rlim_cur)
goto bad_area;
vma->vm_offset -= vma->vm_start - (address & PAGE_MASK);
vma->vm_start = (address & PAGE_MASK);
/*
* Ok, we have a good vm_area for this memory access, so
* we can handle it..
*/
good_area:
/*
* was it a write?
*/
if (error_code & 2) {
if (!(vma->vm_flags & VM_WRITE))
goto bad_area;
} else {
/* read with protection fault? */
if (error_code & 1)
goto bad_area;
if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
goto bad_area;
}
/*
* Did it hit the DOS screen memory VA from vm86 mode?
*/
if (regs->eflags & VM_MASK) {
unsigned long bit = (address - 0xA0000) >> PAGE_SHIFT;
if (bit < 32)
current->tss.screen_bitmap |= 1 << bit;
}
if (error_code & 1) {
#ifdef CONFIG_TEST_VERIFY_AREA
if (regs->cs == KERNEL_CS)
printk("WP fault at %08x\n", regs->eip);
#endif
do_wp_page(vma, address, error_code & 2);
return;
}
do_no_page(vma, address, error_code & 2);
return;
/*
* Something tried to access memory that isn't in our memory map..
* Fix it, but check if it's kernel or user first..
*/
bad_area:
if (error_code & 4) {
current->tss.cr2 = address;
current->tss.error_code = error_code;
current->tss.trap_no = 14;
send_sig(SIGSEGV, current, 1);
return;
}
/*
* Oops. The kernel tried to access some bad page. We'll have to
* terminate things with extreme prejudice.
*
* First we check if it was the bootup rw-test, though..
*/
if (wp_works_ok < 0 && address == TASK_SIZE && (error_code & 1)) {
wp_works_ok = 1;
pg0[0] = pte_val(mk_pte(0, PAGE_SHARED));
invalidate();
printk("This processor honours the WP bit even when in supervisor mode. Good.\n");
return;
}
if ((unsigned long) (address-TASK_SIZE) < PAGE_SIZE) {
printk(KERN_ALERT "Unable to handle kernel NULL pointer dereference");
pg0[0] = pte_val(mk_pte(0, PAGE_SHARED));
} else
printk(KERN_ALERT "Unable to handle kernel paging request");
printk(" at virtual address %08lx\n",address);
__asm__("movl %%cr3,%0" : "=r" (page));
printk(KERN_ALERT "current->tss.cr3 = %08lx, %%cr3 = %08lx\n",
current->tss.cr3, page);
page = ((unsigned long *) page)[address >> 22];
printk(KERN_ALERT "*pde = %08lx\n", page);
if (page & 1) {
page &= PAGE_MASK;
address &= 0x003ff000;
page = ((unsigned long *) page)[address >> PAGE_SHIFT];
printk(KERN_ALERT "*pte = %08lx\n", page);
}
die_if_kernel("Oops", regs, error_code);
do_exit(SIGKILL);
}
|
