1 /* libunwind - a platform-independent unwind library
2 Copyright (C) 2008 CodeSourcery
3 Copyright 2011 Linaro Limited
4 Copyright (C) 2012 Tommi Rantala <tt.rantala@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 #include "unwind_i.h"
28 #include "offsets.h"
29 #include "ex_tables.h"
30
31 #include <signal.h>
32
33 #define arm_exidx_step UNW_OBJ(arm_exidx_step)
34
35 static inline int
arm_exidx_step(struct cursor *c)36 arm_exidx_step (struct cursor *c)
37 {
38 unw_word_t old_ip, old_cfa;
39 uint8_t buf[32];
40 int ret;
41
42 old_ip = c->dwarf.ip;
43 old_cfa = c->dwarf.cfa;
44
45 /* mark PC unsaved */
46 c->dwarf.loc[UNW_ARM_R15] = DWARF_NULL_LOC;
47 unw_word_t ip = c->dwarf.ip;
48 if (c->dwarf.use_prev_instr)
49 /* The least bit denotes thumb/arm mode, clear it. */
50 ip = (ip & ~(unw_word_t)0x1) - 1;
51
52 /* check dynamic info first --- it overrides everything else */
53 ret = unwi_find_dynamic_proc_info (c->dwarf.as, ip, &c->dwarf.pi, 1,
54 c->dwarf.as_arg);
55 if (ret == -UNW_ENOINFO)
56 {
57 if ((ret = tdep_find_proc_info (&c->dwarf, ip, 1)) < 0)
58 return ret;
59 }
60
61 if (c->dwarf.pi.format != UNW_INFO_FORMAT_ARM_EXIDX)
62 return -UNW_ENOINFO;
63
64 ret = arm_exidx_extract (&c->dwarf, buf);
65 if (ret == -UNW_ESTOPUNWIND)
66 return 0;
67 else if (ret < 0)
68 return ret;
69
70 ret = arm_exidx_decode (buf, ret, &c->dwarf);
71 if (ret < 0)
72 return ret;
73
74 if (c->dwarf.ip == old_ip && c->dwarf.cfa == old_cfa)
75 {
76 Dprintf ("%s: ip and cfa unchanged; stopping here (ip=0x%lx)\n",
77 __FUNCTION__, (long) c->dwarf.ip);
78 return -UNW_EBADFRAME;
79 }
80
81 c->dwarf.pi_valid = 0;
82
83 return (c->dwarf.ip == 0) ? 0 : 1;
84 }
85
86 int
unw_step(unw_cursor_t *cursor)87 unw_step (unw_cursor_t *cursor)
88 {
89 struct cursor *c = (struct cursor *) cursor;
90 int ret = -UNW_EUNSPEC;
91
92 Debug (1, "(cursor=%p)\n", c);
93
94 /* Check if this is a signal frame. */
95 if (unw_is_signal_frame (cursor) > 0)
96 return arm_handle_signal_frame (cursor);
97
98 #ifdef CONFIG_DEBUG_FRAME
99 /* First, try DWARF-based unwinding. */
100 if (UNW_TRY_METHOD(UNW_ARM_METHOD_DWARF))
101 {
102 ret = dwarf_step (&c->dwarf);
103 Debug(1, "dwarf_step()=%d\n", ret);
104
105 if (likely (ret > 0))
106 return 1;
107 else if (unlikely (ret == -UNW_ESTOPUNWIND))
108 return ret;
109
110 if (ret < 0 && ret != -UNW_ENOINFO)
111 {
112 Debug (2, "returning %d\n", ret);
113 return ret;
114 }
115 }
116 #endif /* CONFIG_DEBUG_FRAME */
117
118 /* Next, try extbl-based unwinding. */
119 if (UNW_TRY_METHOD (UNW_ARM_METHOD_EXIDX))
120 {
121 Debug (13, "%s(ret=%d), trying extbl\n",
122 UNW_TRY_METHOD(UNW_ARM_METHOD_DWARF) ? "dwarf_step() failed " : "",
123 ret);
124 ret = arm_exidx_step (c);
125 if (ret > 0)
126 return 1;
127 if (ret == -UNW_ESTOPUNWIND || ret == 0)
128 return ret;
129 }
130
131 /* Fall back on APCS frame parsing.
132 Note: This won't work in case the ARM EABI is used. */
133 #ifdef __FreeBSD__
134 if (0)
135 #else
136 if (unlikely (ret < 0))
137 #endif
138 {
139 if (UNW_TRY_METHOD(UNW_ARM_METHOD_FRAME))
140 {
141 Debug (13, "%s%s%s%s(ret=%d), trying frame-chain\n",
142 UNW_TRY_METHOD(UNW_ARM_METHOD_DWARF) ? "dwarf_step() " : "",
143 (UNW_TRY_METHOD(UNW_ARM_METHOD_DWARF) && UNW_TRY_METHOD(UNW_ARM_METHOD_EXIDX)) ? "and " : "",
144 UNW_TRY_METHOD(UNW_ARM_METHOD_EXIDX) ? "arm_exidx_step() " : "",
145 (UNW_TRY_METHOD(UNW_ARM_METHOD_DWARF) || UNW_TRY_METHOD(UNW_ARM_METHOD_EXIDX)) ? "failed " : "",
146 ret);
147 ret = UNW_ESUCCESS;
148 /* DWARF unwinding failed, try to follow APCS/optimized APCS frame chain */
149 unw_word_t instr, i;
150 dwarf_loc_t ip_loc, fp_loc;
151 unw_word_t frame;
152 /* Mark all registers unsaved, since we don't know where
153 they are saved (if at all), except for the EBP and
154 EIP. */
155 if (dwarf_get(&c->dwarf, c->dwarf.loc[UNW_ARM_R11], &frame) < 0)
156 {
157 return 0;
158 }
159 for (i = 0; i < DWARF_NUM_PRESERVED_REGS; ++i) {
160 c->dwarf.loc[i] = DWARF_NULL_LOC;
161 }
162 if (frame)
163 {
164 if (dwarf_get(&c->dwarf, DWARF_LOC(frame, 0), &instr) < 0)
165 {
166 return 0;
167 }
168 instr -= 8;
169 if (dwarf_get(&c->dwarf, DWARF_LOC(instr, 0), &instr) < 0)
170 {
171 return 0;
172 }
173 if ((instr & 0xFFFFD800) == 0xE92DD800)
174 {
175 /* Standard APCS frame. */
176 ip_loc = DWARF_LOC(frame - 4, 0);
177 fp_loc = DWARF_LOC(frame - 12, 0);
178 }
179 else
180 {
181 /* Codesourcery optimized normal frame. */
182 ip_loc = DWARF_LOC(frame, 0);
183 fp_loc = DWARF_LOC(frame - 4, 0);
184 }
185 if (dwarf_get(&c->dwarf, ip_loc, &c->dwarf.ip) < 0)
186 {
187 return 0;
188 }
189 c->dwarf.loc[UNW_ARM_R12] = ip_loc;
190 c->dwarf.loc[UNW_ARM_R11] = fp_loc;
191 c->dwarf.pi_valid = 0;
192 Debug(15, "ip=%x\n", c->dwarf.ip);
193 }
194 else
195 {
196 ret = -UNW_ENOINFO;
197 }
198 }
199 }
200 return ret == -UNW_ENOINFO ? 0 : ret;
201 }
202