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
|
/* Exception handling and frame unwind runtime interface routines.
Copyright (C) 2001 Free Software Foundation, Inc.
This file is part of GNU CC.
GNU CC is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.
GNU CC is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with GNU CC; see the file COPYING. If not, write to
the Free Software Foundation, 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA. */
/* @@@ Really this should be out of line, but this also causes link
compatibility problems with the base ABI. This is slightly better
than duplicating code, however. */
/* Pointer encodings, from dwarf2.h. */
#define DW_EH_PE_absptr 0x00
#define DW_EH_PE_omit 0xff
#define DW_EH_PE_uleb128 0x01
#define DW_EH_PE_udata2 0x02
#define DW_EH_PE_udata4 0x03
#define DW_EH_PE_udata8 0x04
#define DW_EH_PE_sleb128 0x09
#define DW_EH_PE_sdata2 0x0A
#define DW_EH_PE_sdata4 0x0B
#define DW_EH_PE_sdata8 0x0C
#define DW_EH_PE_signed 0x08
#define DW_EH_PE_pcrel 0x10
#define DW_EH_PE_textrel 0x20
#define DW_EH_PE_datarel 0x30
#define DW_EH_PE_funcrel 0x40
#define DW_EH_PE_indirect 0x80
/* Given an encoding, return the number of bytes the format occupies.
This is only defined for fixed-size encodings, and so does not
include leb128. */
static unsigned int
size_of_encoded_value (unsigned char encoding)
{
if (encoding == DW_EH_PE_omit)
return 0;
switch (encoding & 0x07)
{
case DW_EH_PE_absptr:
return sizeof (void *);
case DW_EH_PE_udata2:
return 2;
case DW_EH_PE_udata4:
return 4;
case DW_EH_PE_udata8:
return 8;
}
abort ();
}
/* Given an encoding and an _Unwind_Context, return the base to which
the encoding is relative. This base may then be passed to
read_encoded_value_with_base for use when the _Unwind_Context is
not available. */
static _Unwind_Ptr
base_of_encoded_value (unsigned char encoding, _Unwind_Context *context)
{
if (encoding == DW_EH_PE_omit)
return 0;
switch (encoding & 0x70)
{
case DW_EH_PE_absptr:
case DW_EH_PE_pcrel:
return 0;
case DW_EH_PE_textrel:
return _Unwind_GetTextRelBase (context);
case DW_EH_PE_datarel:
return _Unwind_GetDataRelBase (context);
case DW_EH_PE_funcrel:
return _Unwind_GetRegionStart (context);
}
abort ();
}
/* Load an encoded value from memory at P. The value is returned in VAL;
The function returns P incremented past the value. BASE is as given
by base_of_encoded_value for this encoding in the appropriate context. */
static const unsigned char *
read_encoded_value_with_base (unsigned char encoding, _Unwind_Ptr base,
const unsigned char *p, _Unwind_Ptr *val)
{
union unaligned
{
void *ptr;
unsigned u2 __attribute__ ((mode (HI)));
unsigned u4 __attribute__ ((mode (SI)));
unsigned u8 __attribute__ ((mode (DI)));
signed s2 __attribute__ ((mode (HI)));
signed s4 __attribute__ ((mode (SI)));
signed s8 __attribute__ ((mode (DI)));
} __attribute__((__packed__));
union unaligned *u = (union unaligned *) p;
_Unwind_Ptr result;
switch (encoding & 0x0f)
{
case DW_EH_PE_absptr:
result = (_Unwind_Ptr) u->ptr;
p += sizeof (void *);
break;
case DW_EH_PE_uleb128:
{
unsigned int shift = 0;
unsigned char byte;
result = 0;
do
{
byte = *p++;
result |= (_Unwind_Ptr)(byte & 0x7f) << shift;
shift += 7;
}
while (byte & 0x80);
}
break;
case DW_EH_PE_sleb128:
{
unsigned int shift = 0;
unsigned char byte;
result = 0;
do
{
byte = *p++;
result |= (_Unwind_Ptr)(byte & 0x7f) << shift;
shift += 7;
}
while (byte & 0x80);
if (shift < 8 * sizeof(result) && (byte & 0x40) != 0)
result |= -(1L << shift);
}
break;
case DW_EH_PE_udata2:
result = u->u2;
p += 2;
break;
case DW_EH_PE_udata4:
result = u->u4;
p += 4;
break;
case DW_EH_PE_udata8:
result = u->u8;
p += 8;
break;
case DW_EH_PE_sdata2:
result = u->s2;
p += 2;
break;
case DW_EH_PE_sdata4:
result = u->s4;
p += 4;
break;
case DW_EH_PE_sdata8:
result = u->s8;
p += 8;
break;
default:
abort ();
}
if (result != 0)
{
result += ((encoding & 0x70) == DW_EH_PE_pcrel ? (_Unwind_Ptr)u : base);
if (encoding & DW_EH_PE_indirect)
result = *(_Unwind_Ptr *)result;
}
*val = result;
return p;
}
/* Like read_encoded_value_with_base, but get the base from the context
rather than providing it directly. */
static inline const unsigned char *
read_encoded_value (_Unwind_Context *context, unsigned char encoding,
const unsigned char *p, _Unwind_Ptr *val)
{
return read_encoded_value_with_base (encoding,
base_of_encoded_value (encoding, context),
p, val);
}
/* Read an unsigned leb128 value from P, store the value in VAL, return
P incremented past the value. */
static inline const unsigned char *
read_uleb128 (const unsigned char *p, _Unwind_Ptr *val)
{
return read_encoded_value_with_base (DW_EH_PE_uleb128, 0, p, val);
}
/* Similar, but read a signed leb128 value. */
static inline const unsigned char *
read_sleb128 (const unsigned char *p, _Unwind_Ptr *val)
{
return read_encoded_value_with_base (DW_EH_PE_sleb128, 0, p, val);
}
|
