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
|
// SPDX-License-Identifier: GPL-2.0-only
/*
* Memory fault handling for Hexagon
*
* Copyright (c) 2010-2011, The Linux Foundation. All rights reserved.
*/
/*
* Page fault handling for the Hexagon Virtual Machine.
* Can also be called by a native port emulating the HVM
* execptions.
*/
#include <asm/traps.h>
#include <linux/uaccess.h>
#include <linux/mm.h>
#include <linux/sched/signal.h>
#include <linux/signal.h>
#include <linux/extable.h>
#include <linux/hardirq.h>
#include <linux/perf_event.h>
/*
* Decode of hardware exception sends us to one of several
* entry points. At each, we generate canonical arguments
* for handling by the abstract memory management code.
*/
#define FLT_IFETCH -1
#define FLT_LOAD 0
#define FLT_STORE 1
/*
* Canonical page fault handler
*/
void do_page_fault(unsigned long address, long cause, struct pt_regs *regs)
{
struct vm_area_struct *vma;
struct mm_struct *mm = current->mm;
int si_signo;
int si_code = SEGV_MAPERR;
vm_fault_t fault;
const struct exception_table_entry *fixup;
unsigned int flags = FAULT_FLAG_DEFAULT;
/*
* If we're in an interrupt or have no user context,
* then must not take the fault.
*/
if (unlikely(in_interrupt() || !mm))
goto no_context;
local_irq_enable();
if (user_mode(regs))
flags |= FAULT_FLAG_USER;
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
retry:
vma = lock_mm_and_find_vma(mm, address, regs);
if (unlikely(!vma))
goto bad_area_nosemaphore;
/* Address space is OK. Now check access rights. */
si_code = SEGV_ACCERR;
switch (cause) {
case FLT_IFETCH:
if (!(vma->vm_flags & VM_EXEC))
goto bad_area;
break;
case FLT_LOAD:
if (!(vma->vm_flags & VM_READ))
goto bad_area;
break;
case FLT_STORE:
if (!(vma->vm_flags & VM_WRITE))
goto bad_area;
flags |= FAULT_FLAG_WRITE;
break;
}
fault = handle_mm_fault(vma, address, flags, regs);
if (fault_signal_pending(fault, regs)) {
if (!user_mode(regs))
goto no_context;
return;
}
/* The fault is fully completed (including releasing mmap lock) */
if (fault & VM_FAULT_COMPLETED)
return;
/* The most common case -- we are done. */
if (likely(!(fault & VM_FAULT_ERROR))) {
if (fault & VM_FAULT_RETRY) {
flags |= FAULT_FLAG_TRIED;
goto retry;
}
mmap_read_unlock(mm);
return;
}
mmap_read_unlock(mm);
/* Handle copyin/out exception cases */
if (!user_mode(regs))
goto no_context;
if (fault & VM_FAULT_OOM) {
pagefault_out_of_memory();
return;
}
/* User-mode address is in the memory map, but we are
* unable to fix up the page fault.
*/
if (fault & VM_FAULT_SIGBUS) {
si_signo = SIGBUS;
si_code = BUS_ADRERR;
}
/* Address is not in the memory map */
else {
si_signo = SIGSEGV;
si_code = SEGV_ACCERR;
}
force_sig_fault(si_signo, si_code, (void __user *)address);
return;
bad_area:
mmap_read_unlock(mm);
bad_area_nosemaphore:
if (user_mode(regs)) {
force_sig_fault(SIGSEGV, si_code, (void __user *)address);
return;
}
/* Kernel-mode fault falls through */
no_context:
fixup = search_exception_tables(pt_elr(regs));
if (fixup) {
pt_set_elr(regs, fixup->fixup);
return;
}
/* Things are looking very, very bad now */
bust_spinlocks(1);
printk(KERN_EMERG "Unable to handle kernel paging request at "
"virtual address 0x%08lx, regs %p\n", address, regs);
die("Bad Kernel VA", regs, SIGKILL);
}
void read_protection_fault(struct pt_regs *regs)
{
unsigned long badvadr = pt_badva(regs);
do_page_fault(badvadr, FLT_LOAD, regs);
}
void write_protection_fault(struct pt_regs *regs)
{
unsigned long badvadr = pt_badva(regs);
do_page_fault(badvadr, FLT_STORE, regs);
}
void execute_protection_fault(struct pt_regs *regs)
{
unsigned long badvadr = pt_badva(regs);
do_page_fault(badvadr, FLT_IFETCH, regs);
}
|
