UnwindPtrace.cpp revision c58287d60166ebdb1bd39fa40e5524c868c73a9b 
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
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    // 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
49bool 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
121std::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//-------------------------------------------------------------------------
136Backtrace* CreatePtraceObj(pid_t pid, pid_t tid, BacktraceMap* map) {
137  return new BacktracePtrace(new UnwindPtrace(), pid, tid, map);
138}
139