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
|
/*
* linux/arch/alpha/mm/fault.c
*
* Copyright (C) 1995 Linus Torvalds
*/
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <asm/io.h>
#define __EXTERN_INLINE inline
#include <asm/mmu_context.h>
#include <asm/pgtable.h>
#undef __EXTERN_INLINE
#include <linux/signal.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/ptrace.h>
#include <linux/mman.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>
#include <asm/system.h>
#include <asm/uaccess.h>
extern void die_if_kernel(char *,struct pt_regs *,long, unsigned long *);
/*
* Force a new ASN for a task.
*/
#ifndef __SMP__
unsigned long last_asn = ASN_FIRST_VERSION;
#endif
void
get_new_mmu_context(struct task_struct *p, struct mm_struct *mm)
{
unsigned long new = __get_new_mmu_context(p, mm);
p->tss.mm_context = new;
p->tss.asn = new & HARDWARE_ASN_MASK;
}
/*
* This routine handles page faults. It determines the address,
* and the problem, and then passes it off to handle_mm_fault().
*
* mmcsr:
* 0 = translation not valid
* 1 = access violation
* 2 = fault-on-read
* 3 = fault-on-execute
* 4 = fault-on-write
*
* cause:
* -1 = instruction fetch
* 0 = load
* 1 = store
*
* Registers $9 through $15 are saved in a block just prior to `regs' and
* are saved and restored around the call to allow exception code to
* modify them.
*/
/* Macro for exception fixup code to access integer registers. */
#define dpf_reg(r) \
(((unsigned long *)regs)[(r) <= 8 ? (r) : (r) <= 15 ? (r)-16 : \
(r) <= 18 ? (r)+8 : (r)-10])
asmlinkage void
do_page_fault(unsigned long address, unsigned long mmcsr,
long cause, struct pt_regs *regs)
{
struct vm_area_struct * vma;
struct mm_struct *mm = current->mm;
unsigned fixup;
/* As of EV6, a load into $31/$f31 is a prefetch, and never faults
(or is suppressed by the PALcode). Support that for older CPUs
by ignoring such an instruction. */
if (cause == 0) {
unsigned int insn;
__get_user(insn, (unsigned int *)regs->pc);
if ((insn >> 21 & 0x1f) == 0x1f &&
/* ldq ldl ldt lds ldg ldf ldwu ldbu */
(1ul << (insn >> 26) & 0x30f00001400ul)) {
regs->pc += 4;
return;
}
}
down(&mm->mmap_sem);
lock_kernel();
vma = find_vma(mm, address);
if (!vma)
goto bad_area;
if (vma->vm_start <= address)
goto good_area;
if (!(vma->vm_flags & VM_GROWSDOWN))
goto bad_area;
if (expand_stack(vma, address))
goto bad_area;
/*
* Ok, we have a good vm_area for this memory access, so
* we can handle it..
*/
good_area:
if (cause < 0) {
if (!(vma->vm_flags & VM_EXEC))
goto bad_area;
} else if (!cause) {
/* Allow reads even for write-only mappings */
if (!(vma->vm_flags & (VM_READ | VM_WRITE)))
goto bad_area;
} else {
if (!(vma->vm_flags & VM_WRITE))
goto bad_area;
}
handle_mm_fault(current, vma, address, cause > 0);
up(&mm->mmap_sem);
goto out;
/*
* 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:
up(&mm->mmap_sem);
if (user_mode(regs)) {
force_sig(SIGSEGV, current);
goto out;
}
/* Are we prepared to handle this fault as an exception? */
if ((fixup = search_exception_table(regs->pc)) != 0) {
unsigned long newpc;
newpc = fixup_exception(dpf_reg, fixup, regs->pc);
printk("%s: Exception at [<%lx>] (%lx)\n",
current->comm, regs->pc, newpc);
regs->pc = newpc;
goto out;
}
/*
* Oops. The kernel tried to access some bad page. We'll have to
* terminate things with extreme prejudice.
*/
printk(KERN_ALERT "Unable to handle kernel paging request at "
"virtual address %016lx\n", address);
die_if_kernel("Oops", regs, cause, (unsigned long*)regs - 16);
do_exit(SIGKILL);
out:
unlock_kernel();
}
|
