UnwindPtrace.cpp revision 9846497f7926fc3240c2893d89e60880c22d1fd6 
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#define LOG_TAG "libbacktrace"
18
19#include <backtrace/backtrace.h>
20
21#include <sys/types.h>
22#include <string.h>
23
24#include <cutils/log.h>
25
26#include <libunwind.h>
27#include <libunwind-ptrace.h>
28
29#include "UnwindPtrace.h"
30
31UnwindPtrace::UnwindPtrace() : addr_space_(NULL), upt_info_(NULL) {
32}
33
34UnwindPtrace::~UnwindPtrace() {
35  if (upt_info_) {
36    _UPT_destroy(upt_info_);
37    upt_info_ = NULL;
38  }
39  if (addr_space_) {
40    unw_destroy_addr_space(addr_space_);
41    addr_space_ = NULL;
42  }
43}
44
45bool UnwindPtrace::Unwind(size_t num_ignore_frames) {
46  addr_space_ = unw_create_addr_space(&_UPT_accessors, 0);
47  if (!addr_space_) {
48    BACK_LOGW("unw_create_addr_space failed.");
49    return false;
50  }
51
52  upt_info_ = reinterpret_cast<struct UPT_info*>(_UPT_create(backtrace_obj_->Tid()));
53  if (!upt_info_) {
54    BACK_LOGW("Failed to create upt info.");
55    return false;
56  }
57
58  backtrace_t* backtrace = GetBacktraceData();
59  backtrace->num_frames = 0;
60
61  unw_cursor_t cursor;
62  int ret = unw_init_remote(&cursor, addr_space_, upt_info_);
63  if (ret < 0) {
64    BACK_LOGW("unw_init_remote failed %d", ret);
65    return false;
66  }
67
68  do {
69    unw_word_t pc;
70    ret = unw_get_reg(&cursor, UNW_REG_IP, &pc);
71    if (ret < 0) {
72      BACK_LOGW("Failed to read IP %d", ret);
73      break;
74    }
75    unw_word_t sp;
76    ret = unw_get_reg(&cursor, UNW_REG_SP, &sp);
77    if (ret < 0) {
78      BACK_LOGW("Failed to read SP %d", ret);
79      break;
80    }
81
82    if (num_ignore_frames == 0) {
83      size_t num_frames = backtrace->num_frames;
84      backtrace_frame_data_t* frame = &backtrace->frames[num_frames];
85      frame->pc = static_cast<uintptr_t>(pc);
86      frame->sp = static_cast<uintptr_t>(sp);
87      frame->stack_size = 0;
88      frame->map_name = NULL;
89      frame->map_offset = 0;
90      frame->func_name = NULL;
91      frame->func_offset = 0;
92
93      if (num_frames > 0) {
94        backtrace_frame_data_t* prev = &backtrace->frames[num_frames-1];
95        prev->stack_size = frame->sp - prev->sp;
96      }
97
98      std::string func_name = backtrace_obj_->GetFunctionName(frame->pc, &frame->func_offset);
99      if (!func_name.empty()) {
100        frame->func_name = strdup(func_name.c_str());
101      }
102
103      uintptr_t map_start;
104      frame->map_name = backtrace_obj_->GetMapName(frame->pc, &map_start);
105      if (frame->map_name) {
106        frame->map_offset = frame->pc - map_start;
107      }
108
109      backtrace->num_frames++;
110    } else {
111      num_ignore_frames--;
112    }
113    ret = unw_step (&cursor);
114  } while (ret > 0 && backtrace->num_frames < MAX_BACKTRACE_FRAMES);
115
116  return true;
117}
118
119std::string UnwindPtrace::GetFunctionNameRaw(uintptr_t pc, uintptr_t* offset) {
120  *offset = 0;
121  char buf[512];
122  unw_word_t value;
123  if (unw_get_proc_name_by_ip(addr_space_, pc, buf, sizeof(buf), &value,
124                              upt_info_) >= 0 && buf[0] != '\0') {
125    *offset = static_cast<uintptr_t>(value);
126    return buf;
127  }
128  return "";
129}
130
131//-------------------------------------------------------------------------
132// C++ object creation function.
133//-------------------------------------------------------------------------
134Backtrace* CreatePtraceObj(pid_t pid, pid_t tid, backtrace_map_info_t* map_info) {
135  return new BacktracePtrace(new UnwindPtrace(), pid, tid, map_info);
136}
137