1 /*
2 * Copyright (C) 2013 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #include <backtrace/Backtrace.h>
18 #include <backtrace/BacktraceMap.h>
19
20 #include <sys/types.h>
21 #include <string.h>
22 #include <ucontext.h>
23
24 #include <libunwind.h>
25 #include <libunwind-ptrace.h>
26
27 #include "BacktraceLog.h"
28 #include "UnwindMap.h"
29 #include "UnwindPtrace.h"
30
UnwindPtrace()31 UnwindPtrace::UnwindPtrace() : addr_space_(NULL), upt_info_(NULL) {
32 }
33
~UnwindPtrace()34 UnwindPtrace::~UnwindPtrace() {
35 if (upt_info_) {
36 _UPT_destroy(upt_info_);
37 upt_info_ = NULL;
38 }
39 if (addr_space_) {
40 // Remove the map from the address space before destroying it.
41 // It will be freed in the UnwindMap destructor.
42 unw_map_set(addr_space_, NULL);
43
44 unw_destroy_addr_space(addr_space_);
45 addr_space_ = NULL;
46 }
47 }
48
Unwind(size_t num_ignore_frames,ucontext_t * ucontext)49 bool UnwindPtrace::Unwind(size_t num_ignore_frames, ucontext_t* ucontext) {
50 if (ucontext) {
51 BACK_LOGW("Unwinding from a specified context not supported yet.");
52 return false;
53 }
54
55 addr_space_ = unw_create_addr_space(&_UPT_accessors, 0);
56 if (!addr_space_) {
57 BACK_LOGW("unw_create_addr_space failed.");
58 return false;
59 }
60
61 UnwindMap* map = static_cast<UnwindMap*>(GetMap());
62 unw_map_set(addr_space_, map->GetMapCursor());
63
64 upt_info_ = reinterpret_cast<struct UPT_info*>(_UPT_create(Tid()));
65 if (!upt_info_) {
66 BACK_LOGW("Failed to create upt info.");
67 return false;
68 }
69
70 unw_cursor_t cursor;
71 int ret = unw_init_remote(&cursor, addr_space_, upt_info_);
72 if (ret < 0) {
73 BACK_LOGW("unw_init_remote failed %d", ret);
74 return false;
75 }
76
77 std::vector<backtrace_frame_data_t>* frames = GetFrames();
78 frames->reserve(MAX_BACKTRACE_FRAMES);
79 size_t num_frames = 0;
80 do {
81 unw_word_t pc;
82 ret = unw_get_reg(&cursor, UNW_REG_IP, &pc);
83 if (ret < 0) {
84 BACK_LOGW("Failed to read IP %d", ret);
85 break;
86 }
87 unw_word_t sp;
88 ret = unw_get_reg(&cursor, UNW_REG_SP, &sp);
89 if (ret < 0) {
90 BACK_LOGW("Failed to read SP %d", ret);
91 break;
92 }
93
94 if (num_ignore_frames == 0) {
95 frames->resize(num_frames+1);
96 backtrace_frame_data_t* frame = &frames->at(num_frames);
97 frame->num = num_frames;
98 frame->pc = static_cast<uintptr_t>(pc);
99 frame->sp = static_cast<uintptr_t>(sp);
100 frame->stack_size = 0;
101
102 if (num_frames > 0) {
103 backtrace_frame_data_t* prev = &frames->at(num_frames-1);
104 prev->stack_size = frame->sp - prev->sp;
105 }
106
107 frame->func_name = GetFunctionName(frame->pc, &frame->func_offset);
108
109 frame->map = FindMap(frame->pc);
110
111 num_frames++;
112 } else {
113 num_ignore_frames--;
114 }
115 ret = unw_step (&cursor);
116 } while (ret > 0 && num_frames < MAX_BACKTRACE_FRAMES);
117
118 return true;
119 }
120
GetFunctionNameRaw(uintptr_t pc,uintptr_t * offset)121 std::string UnwindPtrace::GetFunctionNameRaw(uintptr_t pc, uintptr_t* offset) {
122 *offset = 0;
123 char buf[512];
124 unw_word_t value;
125 if (unw_get_proc_name_by_ip(addr_space_, pc, buf, sizeof(buf), &value,
126 upt_info_) >= 0 && buf[0] != '\0') {
127 *offset = static_cast<uintptr_t>(value);
128 return buf;
129 }
130 return "";
131 }
132
133 //-------------------------------------------------------------------------
134 // C++ object creation function.
135 //-------------------------------------------------------------------------
CreatePtraceObj(pid_t pid,pid_t tid,BacktraceMap * map)136 Backtrace* CreatePtraceObj(pid_t pid, pid_t tid, BacktraceMap* map) {
137 return new BacktracePtrace(new UnwindPtrace(), pid, tid, map);
138 }
139