1 /*
2 * Copyright (C) 2012 The Android Open Source Project
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * * Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * * Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in
12 * the documentation and/or other materials provided with the
13 * distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
16 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
17 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
18 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
19 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
22 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
25 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29 #include <cxxabi.h>
30 #include <dlfcn.h>
31 #include <errno.h>
32 #include <inttypes.h>
33 #include <malloc.h>
34 #include <pthread.h>
35 #include <string.h>
36 #include <sys/types.h>
37 #include <unistd.h>
38 #include <unwind.h>
39
40 #include "MapData.h"
41 #include "backtrace.h"
42 #include "debug_log.h"
43
44 #if defined(__LP64__)
45 #define PAD_PTR "016" PRIxPTR
46 #else
47 #define PAD_PTR "08" PRIxPTR
48 #endif
49
50 typedef struct _Unwind_Context __unwind_context;
51
52 static MapData g_map_data;
53 static MapEntry g_current_code_map;
54
find_current_map(__unwind_context * context,void *)55 static _Unwind_Reason_Code find_current_map(__unwind_context* context, void*) {
56 uintptr_t ip = _Unwind_GetIP(context);
57
58 if (ip == 0) {
59 return _URC_END_OF_STACK;
60 }
61 auto map = g_map_data.find(ip);
62 if (map != nullptr) {
63 g_current_code_map = *map;
64 }
65 return _URC_END_OF_STACK;
66 }
67
backtrace_startup()68 void backtrace_startup() {
69 g_map_data.ReadMaps();
70 _Unwind_Backtrace(find_current_map, nullptr);
71 }
72
backtrace_shutdown()73 void backtrace_shutdown() {}
74
75 struct stack_crawl_state_t {
76 uintptr_t* frames;
77 size_t frame_count;
78 size_t cur_frame = 0;
79
stack_crawl_state_tstack_crawl_state_t80 stack_crawl_state_t(uintptr_t* frames, size_t frame_count)
81 : frames(frames), frame_count(frame_count) {}
82 };
83
trace_function(__unwind_context * context,void * arg)84 static _Unwind_Reason_Code trace_function(__unwind_context* context, void* arg) {
85 stack_crawl_state_t* state = static_cast<stack_crawl_state_t*>(arg);
86
87 uintptr_t ip = _Unwind_GetIP(context);
88
89 // `ip` is the address of the instruction *after* the call site in
90 // `context`, so we want to back up by one instruction. This is hard for
91 // every architecture except arm64, so we just make sure we're *inside*
92 // that instruction, not necessarily at the start of it. (If the value
93 // is too low to be valid, we just leave it alone.)
94 if (ip >= 4096) {
95 #if defined(__aarch64__)
96 ip -= 4; // Exactly.
97 #elif defined(__arm__) || defined(__riscv)
98 ip -= 2; // At least.
99 #elif defined(__i386__) || defined(__x86_64__)
100 ip -= 1; // At least.
101 #endif
102 }
103
104 // Do not record the frames that fall in our own shared library.
105 if (g_current_code_map.start() != 0 && (ip >= g_current_code_map.start()) &&
106 ip < g_current_code_map.end()) {
107 return _URC_NO_REASON;
108 }
109
110 state->frames[state->cur_frame++] = ip;
111 return (state->cur_frame >= state->frame_count) ? _URC_END_OF_STACK : _URC_NO_REASON;
112 }
113
backtrace_get(uintptr_t * frames,size_t frame_count)114 size_t backtrace_get(uintptr_t* frames, size_t frame_count) {
115 stack_crawl_state_t state(frames, frame_count);
116 _Unwind_Backtrace(trace_function, &state);
117 return state.cur_frame;
118 }
119
backtrace_string(const uintptr_t * frames,size_t frame_count)120 std::string backtrace_string(const uintptr_t* frames, size_t frame_count) {
121 if (g_map_data.NumMaps() == 0) {
122 g_map_data.ReadMaps();
123 }
124
125 std::string str;
126
127 for (size_t frame_num = 0; frame_num < frame_count; frame_num++) {
128 uintptr_t offset = 0;
129 const char* symbol = nullptr;
130
131 Dl_info info;
132 if (dladdr(reinterpret_cast<void*>(frames[frame_num]), &info) != 0) {
133 offset = reinterpret_cast<uintptr_t>(info.dli_saddr);
134 symbol = info.dli_sname;
135 } else {
136 info.dli_fname = nullptr;
137 }
138
139 uintptr_t rel_pc = offset;
140 const MapEntry* entry = g_map_data.find(frames[frame_num], &rel_pc);
141
142 const char* soname = (entry != nullptr) ? entry->name().c_str() : info.dli_fname;
143 if (soname == nullptr) {
144 soname = "<unknown>";
145 }
146
147 char offset_buf[128];
148 if (entry != nullptr && entry->elf_start_offset() != 0) {
149 snprintf(offset_buf, sizeof(offset_buf), " (offset 0x%" PRIxPTR ")",
150 entry->elf_start_offset());
151 } else {
152 offset_buf[0] = '\0';
153 }
154
155 char buf[1024];
156 if (symbol != nullptr) {
157 char* demangled_name = abi::__cxa_demangle(symbol, nullptr, nullptr, nullptr);
158 const char* name;
159 if (demangled_name != nullptr) {
160 name = demangled_name;
161 } else {
162 name = symbol;
163 }
164 async_safe_format_buffer(buf, sizeof(buf),
165 " #%02zd pc %" PAD_PTR " %s%s (%s+%" PRIuPTR ")\n",
166 frame_num, rel_pc, soname, offset_buf, name,
167 frames[frame_num] - offset);
168 free(demangled_name);
169 } else {
170 async_safe_format_buffer(buf, sizeof(buf), " #%02zd pc %" PAD_PTR " %s%s\n",
171 frame_num, rel_pc, soname, offset_buf);
172 }
173 str += buf;
174 }
175
176 return str;
177 }
178
backtrace_log(const uintptr_t * frames,size_t frame_count)179 void backtrace_log(const uintptr_t* frames, size_t frame_count) {
180 g_map_data.ReadMaps();
181 error_log_string(backtrace_string(frames, frame_count).c_str());
182 }
183