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
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
|
/* Copyright (C) 2001, 2002, 2007 Free Software Foundation, Inc.
Contributed by Jakub Jelinek <jakub@redhat.com>.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, write to the Free
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA. */
/* Locate the FDE entry for a given address, using PT_GNU_EH_FRAME ELF
segment and dl_iterate_phdr to avoid register/deregister calls at
DSO load/unload. */
#ifdef _LIBC
# include <shlib-compat.h>
#endif
#if !defined _LIBC || SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_2_5)
#include <link.h>
#include <stddef.h>
#define _Unwind_Find_FDE _Unwind_Find_registered_FDE
#include <unwind-dw2-fde.c>
#undef _Unwind_Find_FDE
extern fde * _Unwind_Find_registered_FDE (void *pc,
struct dwarf_eh_bases *bases);
extern fde * _Unwind_Find_FDE (void *, struct dwarf_eh_bases *);
struct unw_eh_callback_data
{
_Unwind_Ptr pc;
void *tbase;
void *dbase;
void *func;
fde *ret;
};
struct unw_eh_frame_hdr
{
unsigned char version;
unsigned char eh_frame_ptr_enc;
unsigned char fde_count_enc;
unsigned char table_enc;
};
/* Like base_of_encoded_value, but take the base from a struct object
instead of an _Unwind_Context. */
static _Unwind_Ptr
base_from_cb_data (unsigned char encoding, struct unw_eh_callback_data *data)
{
if (encoding == DW_EH_PE_omit)
return 0;
switch (encoding & 0x70)
{
case DW_EH_PE_absptr:
case DW_EH_PE_pcrel:
case DW_EH_PE_aligned:
return 0;
case DW_EH_PE_textrel:
return (_Unwind_Ptr) data->tbase;
case DW_EH_PE_datarel:
return (_Unwind_Ptr) data->dbase;
}
abort ();
}
static int
_Unwind_IteratePhdrCallback (struct dl_phdr_info *info, size_t size, void *ptr)
{
struct unw_eh_callback_data *data = (struct unw_eh_callback_data *) ptr;
const ElfW(Phdr) *phdr, *p_eh_frame_hdr, *p_dynamic;
long n, match;
_Unwind_Ptr load_base;
const unsigned char *p;
const struct unw_eh_frame_hdr *hdr;
_Unwind_Ptr eh_frame;
struct object ob;
/* Make sure struct dl_phdr_info is at least as big as we need. */
if (size < offsetof (struct dl_phdr_info, dlpi_phnum)
+ sizeof (info->dlpi_phnum))
return -1;
match = 0;
phdr = info->dlpi_phdr;
load_base = info->dlpi_addr;
p_eh_frame_hdr = NULL;
p_dynamic = NULL;
/* See if PC falls into one of the loaded segments. Find the eh_frame
segment at the same time. */
for (n = info->dlpi_phnum; --n >= 0; phdr++)
{
if (phdr->p_type == PT_LOAD)
{
_Unwind_Ptr vaddr = phdr->p_vaddr + load_base;
if (data->pc >= vaddr && data->pc < vaddr + phdr->p_memsz)
match = 1;
}
else if (phdr->p_type == PT_GNU_EH_FRAME)
p_eh_frame_hdr = phdr;
else if (phdr->p_type == PT_DYNAMIC)
p_dynamic = phdr;
}
if (!match || !p_eh_frame_hdr)
return 0;
/* Read .eh_frame_hdr header. */
hdr = (const struct unw_eh_frame_hdr *)
(p_eh_frame_hdr->p_vaddr + load_base);
if (hdr->version != 1)
return 1;
#ifdef CRT_GET_RFIB_DATA
# ifdef __i386__
data->dbase = NULL;
if (p_dynamic)
{
/* For dynamicly linked executables and shared libraries,
DT_PLTGOT is the gp value for that object. */
ElfW(Dyn) *dyn = (ElfW(Dyn) *)(p_dynamic->p_vaddr + load_base);
for (; dyn->d_tag != DT_NULL ; dyn++)
if (dyn->d_tag == DT_PLTGOT)
{
/* On IA-32, _DYNAMIC is writable and GLIBC has relocated it. */
data->dbase = (void *) dyn->d_un.d_ptr;
break;
}
}
# else
# error What is DW_EH_PE_datarel base on this platform?
# endif
#endif
#ifdef CRT_GET_RFIB_TEXT
# error What is DW_EH_PE_textrel base on this platform?
#endif
p = read_encoded_value_with_base (hdr->eh_frame_ptr_enc,
base_from_cb_data (hdr->eh_frame_ptr_enc,
data),
(const unsigned char *) (hdr + 1),
&eh_frame);
/* We require here specific table encoding to speed things up.
Also, DW_EH_PE_datarel here means using PT_GNU_EH_FRAME start
as base, not the processor specific DW_EH_PE_datarel. */
if (hdr->fde_count_enc != DW_EH_PE_omit
&& hdr->table_enc == (DW_EH_PE_datarel | DW_EH_PE_sdata4))
{
_Unwind_Ptr fde_count;
p = read_encoded_value_with_base (hdr->fde_count_enc,
base_from_cb_data (hdr->fde_count_enc,
data),
p, &fde_count);
/* Shouldn't happen. */
if (fde_count == 0)
return 1;
if ((((_Unwind_Ptr) p) & 3) == 0)
{
struct fde_table {
signed initial_loc __attribute__ ((mode (SI)));
signed fde __attribute__ ((mode (SI)));
};
const struct fde_table *table = (const struct fde_table *) p;
size_t lo, hi, mid;
_Unwind_Ptr data_base = (_Unwind_Ptr) hdr;
fde *f;
unsigned int f_enc, f_enc_size;
_Unwind_Ptr range;
mid = fde_count - 1;
if (data->pc < table[0].initial_loc + data_base)
return 1;
else if (data->pc < table[mid].initial_loc + data_base)
{
lo = 0;
hi = mid;
while (lo < hi)
{
mid = (lo + hi) / 2;
if (data->pc < table[mid].initial_loc + data_base)
hi = mid;
else if (data->pc >= table[mid + 1].initial_loc + data_base)
lo = mid + 1;
else
break;
}
if (lo >= hi)
__gxx_abort ();
}
f = (fde *) (table[mid].fde + data_base);
f_enc = get_fde_encoding (f);
f_enc_size = size_of_encoded_value (f_enc);
read_encoded_value_with_base (f_enc & 0x0f, 0,
&f->pc_begin[f_enc_size], &range);
if (data->pc < table[mid].initial_loc + data_base + range)
data->ret = f;
data->func = (void *) (table[mid].initial_loc + data_base);
return 1;
}
}
/* We have no sorted search table, so need to go the slow way.
As soon as GLIBC will provide API so to notify that a library has been
removed, we could cache this (and thus use search_object). */
ob.pc_begin = NULL;
ob.tbase = data->tbase;
ob.dbase = data->dbase;
ob.u.single = (fde *) eh_frame;
ob.s.i = 0;
ob.s.b.mixed_encoding = 1; /* Need to assume worst case. */
data->ret = linear_search_fdes (&ob, (fde *) eh_frame, (void *) data->pc);
if (data->ret != NULL)
{
unsigned int encoding = get_fde_encoding (data->ret);
_Unwind_Ptr func;
read_encoded_value_with_base (encoding,
base_from_cb_data (encoding, data),
data->ret->pc_begin, &func);
data->func = (void *) func;
}
return 1;
}
# ifdef _LIBC
# define dl_iterate_phdr __dl_iterate_phdr
# endif
fde *
_Unwind_Find_FDE (void *pc, struct dwarf_eh_bases *bases)
{
struct unw_eh_callback_data data;
fde *ret;
ret = _Unwind_Find_registered_FDE (pc, bases);
if (ret != NULL)
return ret;
data.pc = (_Unwind_Ptr) pc;
data.tbase = NULL;
data.dbase = NULL;
data.func = NULL;
data.ret = NULL;
if (dl_iterate_phdr (_Unwind_IteratePhdrCallback, &data) < 0)
return NULL;
if (data.ret)
{
bases->tbase = data.tbase;
bases->dbase = data.dbase;
bases->func = data.func;
}
return data.ret;
}
#endif
|
