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
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
|
/*
* linux/arch/nios2/kernel/misaligned.c
*
* basic emulation for mis-aligned accesses on the NIOS II cpu
* modelled after the version for arm in arm/alignment.c
*
* Brad Parker <brad@heeltoe.com>
* Copyright (C) 2010 Ambient Corporation
* Copyright (c) 2010 Altera Corporation, San Jose, California, USA.
* Copyright (c) 2010 Arrow Electronics, Inc.
*
* This file is subject to the terms and conditions of the GNU General
* Public License. See the file COPYING in the main directory of
* this archive for more details.
*/
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/proc_fs.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/uaccess.h>
#include <linux/seq_file.h>
#include <asm/traps.h>
#include <linux/unaligned.h>
/* instructions we emulate */
#define INST_LDHU 0x0b
#define INST_STH 0x0d
#define INST_LDH 0x0f
#define INST_STW 0x15
#define INST_LDW 0x17
static unsigned int ma_usermode;
#define UM_WARN 0x01
#define UM_FIXUP 0x02
#define UM_SIGNAL 0x04
#define KM_WARN 0x08
/* see arch/nios2/include/asm/ptrace.h */
static u8 sys_stack_frame_reg_offset[] = {
/* struct pt_regs */
8, 9, 10, 11, 12, 13, 14, 15, 1, 2, 3, 4, 5, 6, 7, 0,
/* struct switch_stack */
16, 17, 18, 19, 20, 21, 22, 23, 0, 0, 0, 0, 0, 0, 0, 0
};
static int reg_offsets[32];
static inline u32 get_reg_val(struct pt_regs *fp, int reg)
{
u8 *p = ((u8 *)fp) + reg_offsets[reg];
return *(u32 *)p;
}
static inline void put_reg_val(struct pt_regs *fp, int reg, u32 val)
{
u8 *p = ((u8 *)fp) + reg_offsets[reg];
*(u32 *)p = val;
}
/*
* (mis)alignment handler
*/
asmlinkage void handle_unaligned_c(struct pt_regs *fp, int cause)
{
u32 isn, addr, val;
int in_kernel;
u8 a, b, d0, d1, d2, d3;
s16 imm16;
unsigned int fault;
/* back up one instruction */
fp->ea -= 4;
if (fixup_exception(fp)) {
return;
}
in_kernel = !user_mode(fp);
isn = *(unsigned long *)(fp->ea);
fault = 0;
/* do fixup if in kernel or mode turned on */
if (in_kernel || (ma_usermode & UM_FIXUP)) {
/* decompose instruction */
a = (isn >> 27) & 0x1f;
b = (isn >> 22) & 0x1f;
imm16 = (isn >> 6) & 0xffff;
addr = get_reg_val(fp, a) + imm16;
/* do fixup to saved registers */
switch (isn & 0x3f) {
case INST_LDHU:
fault |= __get_user(d0, (u8 *)(addr+0));
fault |= __get_user(d1, (u8 *)(addr+1));
val = (d1 << 8) | d0;
put_reg_val(fp, b, val);
break;
case INST_STH:
val = get_reg_val(fp, b);
d1 = val >> 8;
d0 = val >> 0;
if (in_kernel) {
*(u8 *)(addr+0) = d0;
*(u8 *)(addr+1) = d1;
} else {
fault |= __put_user(d0, (u8 *)(addr+0));
fault |= __put_user(d1, (u8 *)(addr+1));
}
break;
case INST_LDH:
fault |= __get_user(d0, (u8 *)(addr+0));
fault |= __get_user(d1, (u8 *)(addr+1));
val = (short)((d1 << 8) | d0);
put_reg_val(fp, b, val);
break;
case INST_STW:
val = get_reg_val(fp, b);
d3 = val >> 24;
d2 = val >> 16;
d1 = val >> 8;
d0 = val >> 0;
if (in_kernel) {
*(u8 *)(addr+0) = d0;
*(u8 *)(addr+1) = d1;
*(u8 *)(addr+2) = d2;
*(u8 *)(addr+3) = d3;
} else {
fault |= __put_user(d0, (u8 *)(addr+0));
fault |= __put_user(d1, (u8 *)(addr+1));
fault |= __put_user(d2, (u8 *)(addr+2));
fault |= __put_user(d3, (u8 *)(addr+3));
}
break;
case INST_LDW:
fault |= __get_user(d0, (u8 *)(addr+0));
fault |= __get_user(d1, (u8 *)(addr+1));
fault |= __get_user(d2, (u8 *)(addr+2));
fault |= __get_user(d3, (u8 *)(addr+3));
val = (d3 << 24) | (d2 << 16) | (d1 << 8) | d0;
put_reg_val(fp, b, val);
break;
}
}
addr = RDCTL(CTL_BADADDR);
cause >>= 2;
if (fault) {
if (in_kernel) {
pr_err("fault during kernel misaligned fixup @ %#lx; addr 0x%08x; isn=0x%08x\n",
fp->ea, (unsigned int)addr,
(unsigned int)isn);
} else {
pr_err("fault during user misaligned fixup @ %#lx; isn=%08x addr=0x%08x sp=0x%08lx pid=%d\n",
fp->ea,
(unsigned int)isn, addr, fp->sp,
current->pid);
_exception(SIGSEGV, fp, SEGV_MAPERR, fp->ea);
return;
}
}
/*
* kernel mode -
* note exception and skip bad instruction (return)
*/
if (in_kernel) {
fp->ea += 4;
if (ma_usermode & KM_WARN) {
pr_err("kernel unaligned access @ %#lx; BADADDR 0x%08x; cause=%d, isn=0x%08x\n",
fp->ea,
(unsigned int)addr, cause,
(unsigned int)isn);
/* show_regs(fp); */
}
return;
}
/*
* user mode -
* possibly warn,
* possibly send SIGBUS signal to process
*/
if (ma_usermode & UM_WARN) {
pr_err("user unaligned access @ %#lx; isn=0x%08lx ea=0x%08lx ra=0x%08lx sp=0x%08lx\n",
(unsigned long)addr, (unsigned long)isn,
fp->ea, fp->ra, fp->sp);
}
if (ma_usermode & UM_SIGNAL)
_exception(SIGBUS, fp, BUS_ADRALN, fp->ea);
else
fp->ea += 4; /* else advance */
}
static void __init misaligned_calc_reg_offsets(void)
{
int i, r, offset;
/* pre-calc offsets of registers on sys call stack frame */
offset = 0;
/* struct pt_regs */
for (i = 0; i < 16; i++) {
r = sys_stack_frame_reg_offset[i];
reg_offsets[r] = offset;
offset += 4;
}
/* struct switch_stack */
offset = -sizeof(struct switch_stack);
for (i = 16; i < 32; i++) {
r = sys_stack_frame_reg_offset[i];
reg_offsets[r] = offset;
offset += 4;
}
}
static int __init misaligned_init(void)
{
/* default mode - silent fix */
ma_usermode = UM_FIXUP | KM_WARN;
misaligned_calc_reg_offsets();
return 0;
}
fs_initcall(misaligned_init);
|
