1 /* libunwind - a platform-independent unwind library
2 Copyright (C) 2002 Hewlett-Packard Co
3 Copyright (C) 2007 David Mosberger-Tang
4 Contributed by David Mosberger-Tang <dmosberger@gmail.com>
5
6 This file is part of libunwind.
7
8 Permission is hereby granted, free of charge, to any person obtaining
9 a copy of this software and associated documentation files (the
10 "Software"), to deal in the Software without restriction, including
11 without limitation the rights to use, copy, modify, merge, publish,
12 distribute, sublicense, and/or sell copies of the Software, and to
13 permit persons to whom the Software is furnished to do so, subject to
14 the following conditions:
15
16 The above copyright notice and this permission notice shall be
17 included in all copies or substantial portions of the Software.
18
19 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
20 EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
21 MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
22 NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
23 LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
24 OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
25 WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */
26
27 #ifdef HAVE_CONFIG_H
28 #include <config.h>
29 #endif
30
31 #include <stdlib.h>
32 #include <string.h>
33
34 #include "unwind_i.h"
35
36 #ifdef UNW_REMOTE_ONLY
37
38 /* unw_local_addr_space is a NULL pointer in this case. */
39 unw_addr_space_t unw_local_addr_space;
40
41 #else /* !UNW_REMOTE_ONLY */
42
43 static struct unw_addr_space local_addr_space;
44
45 unw_addr_space_t unw_local_addr_space = &local_addr_space;
46
47 # ifdef UNW_LOCAL_ONLY
48
49 HIDDEN void *
tdep_uc_addr(ucontext_t * uc,int reg)50 tdep_uc_addr (ucontext_t *uc, int reg)
51 {
52 return x86_r_uc_addr (uc, reg);
53 }
54
55 # endif /* UNW_LOCAL_ONLY */
56
57 static void
put_unwind_info(unw_addr_space_t as,unw_proc_info_t * proc_info,void * arg)58 put_unwind_info (unw_addr_space_t as, unw_proc_info_t *proc_info, void *arg)
59 {
60 /* it's a no-op */
61 }
62
63 static int
get_dyn_info_list_addr(unw_addr_space_t as,unw_word_t * dyn_info_list_addr,void * arg)64 get_dyn_info_list_addr (unw_addr_space_t as, unw_word_t *dyn_info_list_addr,
65 void *arg)
66 {
67 #ifndef UNW_LOCAL_ONLY
68 # pragma weak _U_dyn_info_list_addr
69 if (!_U_dyn_info_list_addr)
70 return -UNW_ENOINFO;
71 #endif
72 // Access the `_U_dyn_info_list` from `LOCAL_ONLY` library, i.e. libunwind.so.
73 *dyn_info_list_addr = _U_dyn_info_list_addr ();
74 return 0;
75 }
76
77 #define PAGE_SIZE 4096
78 #define PAGE_START(a) ((a) & ~(PAGE_SIZE-1))
79
80 /* Cache of already validated addresses */
81 #define NLGA 4
82 static unw_word_t last_good_addr[NLGA];
83 static int lga_victim;
84
85 static int
validate_mem(unw_word_t addr)86 validate_mem (unw_word_t addr)
87 {
88 int i, victim;
89 #ifdef HAVE_MINCORE
90 unsigned char mvec[2]; /* Unaligned access may cross page boundary */
91 #endif
92 size_t len;
93
94 if (PAGE_START(addr + sizeof (unw_word_t) - 1) == PAGE_START(addr))
95 len = PAGE_SIZE;
96 else
97 len = PAGE_SIZE * 2;
98
99 addr = PAGE_START(addr);
100
101 if (addr == 0)
102 return -1;
103
104 for (i = 0; i < NLGA; i++)
105 {
106 if (last_good_addr[i] && (addr == last_good_addr[i]))
107 return 0;
108 }
109
110 #ifdef HAVE_MINCORE
111 if (mincore ((void *) addr, len, mvec) == -1)
112 #else
113 if (msync ((void *) addr, len, MS_ASYNC) == -1)
114 #endif
115 return -1;
116
117 victim = lga_victim;
118 for (i = 0; i < NLGA; i++) {
119 if (!last_good_addr[victim]) {
120 last_good_addr[victim++] = addr;
121 return 0;
122 }
123 victim = (victim + 1) % NLGA;
124 }
125
126 /* All slots full. Evict the victim. */
127 last_good_addr[victim] = addr;
128 victim = (victim + 1) % NLGA;
129 lga_victim = victim;
130
131 return 0;
132 }
133
134 static int
access_mem(unw_addr_space_t as,unw_word_t addr,unw_word_t * val,int write,void * arg)135 access_mem (unw_addr_space_t as, unw_word_t addr, unw_word_t *val, int write,
136 void *arg)
137 {
138 if (write)
139 {
140 Debug (16, "mem[%x] <- %x\n", addr, *val);
141 *(unw_word_t *) addr = *val;
142 }
143 else
144 {
145 /* validate address */
146 const struct cursor *c = (const struct cursor *)arg;
147 if (c && c->validate && validate_mem(addr))
148 return -1;
149 *val = *(unw_word_t *) addr;
150 Debug (16, "mem[%x] -> %x\n", addr, *val);
151 }
152 return 0;
153 }
154
155 static int
access_reg(unw_addr_space_t as,unw_regnum_t reg,unw_word_t * val,int write,void * arg)156 access_reg (unw_addr_space_t as, unw_regnum_t reg, unw_word_t *val, int write,
157 void *arg)
158 {
159 unw_word_t *addr;
160 ucontext_t *uc = ((struct cursor *)arg)->uc;
161
162 if (unw_is_fpreg (reg))
163 goto badreg;
164
165 if (!(addr = x86_r_uc_addr (uc, reg)))
166 goto badreg;
167
168 if (write)
169 {
170 *(unw_word_t *) addr = *val;
171 Debug (12, "%s <- %x\n", unw_regname (reg), *val);
172 }
173 else
174 {
175 *val = *(unw_word_t *) addr;
176 Debug (12, "%s -> %x\n", unw_regname (reg), *val);
177 }
178 return 0;
179
180 badreg:
181 Debug (1, "bad register number %u\n", reg);
182 return -UNW_EBADREG;
183 }
184
185 static int
access_fpreg(unw_addr_space_t as,unw_regnum_t reg,unw_fpreg_t * val,int write,void * arg)186 access_fpreg (unw_addr_space_t as, unw_regnum_t reg, unw_fpreg_t *val,
187 int write, void *arg)
188 {
189 ucontext_t *uc = ((struct cursor *)arg)->uc;
190 unw_fpreg_t *addr;
191
192 if (!unw_is_fpreg (reg))
193 goto badreg;
194
195 if (!(addr = x86_r_uc_addr (uc, reg)))
196 goto badreg;
197
198 if (write)
199 {
200 Debug (12, "%s <- %08lx.%08lx.%08lx\n", unw_regname (reg),
201 ((long *)val)[0], ((long *)val)[1], ((long *)val)[2]);
202 *(unw_fpreg_t *) addr = *val;
203 }
204 else
205 {
206 *val = *(unw_fpreg_t *) addr;
207 Debug (12, "%s -> %08lx.%08lx.%08lx\n", unw_regname (reg),
208 ((long *)val)[0], ((long *)val)[1], ((long *)val)[2]);
209 }
210 return 0;
211
212 badreg:
213 Debug (1, "bad register number %u\n", reg);
214 /* attempt to access a non-preserved register */
215 return -UNW_EBADREG;
216 }
217
218 static int
get_static_proc_name(unw_addr_space_t as,unw_word_t ip,char * buf,size_t buf_len,unw_word_t * offp,void * arg)219 get_static_proc_name (unw_addr_space_t as, unw_word_t ip,
220 char *buf, size_t buf_len, unw_word_t *offp,
221 void *arg)
222 {
223 return _Uelf32_get_proc_name (as, getpid (), ip, buf, buf_len, offp);
224 }
225
226 HIDDEN void
x86_local_addr_space_init(void)227 x86_local_addr_space_init (void)
228 {
229 memset (&local_addr_space, 0, sizeof (local_addr_space));
230 local_addr_space.caching_policy = UNWI_DEFAULT_CACHING_POLICY;
231 local_addr_space.acc.find_proc_info = dwarf_find_proc_info;
232 local_addr_space.acc.put_unwind_info = put_unwind_info;
233 local_addr_space.acc.get_dyn_info_list_addr = get_dyn_info_list_addr;
234 local_addr_space.acc.access_mem = access_mem;
235 local_addr_space.acc.access_reg = access_reg;
236 local_addr_space.acc.access_fpreg = access_fpreg;
237 local_addr_space.acc.resume = x86_local_resume;
238 local_addr_space.acc.get_proc_name = get_static_proc_name;
239 unw_flush_cache (&local_addr_space, 0, 0);
240 }
241
242 HIDDEN void
init_local_addr_space(unw_addr_space_t as)243 init_local_addr_space (unw_addr_space_t as)
244 {
245 memset (as, 0, sizeof (struct unw_addr_space));
246 as->caching_policy = UNW_CACHE_GLOBAL;
247 as->acc.find_proc_info = dwarf_find_proc_info;
248 as->acc.put_unwind_info = put_unwind_info;
249 as->acc.get_dyn_info_list_addr = get_dyn_info_list_addr;
250 as->acc.access_mem = access_mem;
251 as->acc.access_reg = access_reg;
252 as->acc.access_fpreg = access_fpreg;
253 as->acc.resume = x86_local_resume;
254 as->acc.get_proc_name = get_static_proc_name;
255 unw_flush_cache (as, 0, 0);
256 }
257
258 #endif /* !UNW_REMOTE_ONLY */
259