UnwindPtrace.cpp revision df2906186b6952c57b1f662bfef0b65c9f8c2e0d 
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#include <backtrace/BacktraceMap.h>
21
22#include <sys/types.h>
23#include <string.h>
24
25#include <libunwind.h>
26#include <libunwind-ptrace.h>
27
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) {
50  addr_space_ = unw_create_addr_space(&_UPT_accessors, 0);
51  if (!addr_space_) {
52    BACK_LOGW("unw_create_addr_space failed.");
53    return false;
54  }
55
56  UnwindMap* map = static_cast<UnwindMap*>(GetMap());
57  unw_map_set(addr_space_, map->GetMapCursor());
58
59  upt_info_ = reinterpret_cast<struct UPT_info*>(_UPT_create(Tid()));
60  if (!upt_info_) {
61    BACK_LOGW("Failed to create upt info.");
62    return false;
63  }
64
65  unw_cursor_t cursor;
66  int ret = unw_init_remote(&cursor, addr_space_, upt_info_);
67  if (ret < 0) {
68    BACK_LOGW("unw_init_remote failed %d", ret);
69    return false;
70  }
71
72  std::vector<backtrace_frame_data_t>* frames = GetFrames();
73  frames->reserve(MAX_BACKTRACE_FRAMES);
74  size_t num_frames = 0;
75  do {
76    unw_word_t pc;
77    ret = unw_get_reg(&cursor, UNW_REG_IP, &pc);
78    if (ret < 0) {
79      BACK_LOGW("Failed to read IP %d", ret);
80      break;
81    }
82    unw_word_t sp;
83    ret = unw_get_reg(&cursor, UNW_REG_SP, &sp);
84    if (ret < 0) {
85      BACK_LOGW("Failed to read SP %d", ret);
86      break;
87    }
88
89    if (num_ignore_frames == 0) {
90      frames->resize(num_frames+1);
91      backtrace_frame_data_t* frame = &frames->at(num_frames);
92      frame->num = num_frames;
93      frame->pc = static_cast<uintptr_t>(pc);
94      frame->sp = static_cast<uintptr_t>(sp);
95      frame->stack_size = 0;
96
97      if (num_frames > 0) {
98        backtrace_frame_data_t* prev = &frames->at(num_frames-1);
99        prev->stack_size = frame->sp - prev->sp;
100      }
101
102      frame->func_name = GetFunctionName(frame->pc, &frame->func_offset);
103
104      frame->map = FindMap(frame->pc);
105
106      num_frames++;
107    } else {
108      num_ignore_frames--;
109    }
110    ret = unw_step (&cursor);
111  } while (ret > 0 && num_frames < MAX_BACKTRACE_FRAMES);
112
113  return true;
114}
115
116std::string UnwindPtrace::GetFunctionNameRaw(uintptr_t pc, uintptr_t* offset) {
117  *offset = 0;
118  char buf[512];
119  unw_word_t value;
120  if (unw_get_proc_name_by_ip(addr_space_, pc, buf, sizeof(buf), &value,
121                              upt_info_) >= 0 && buf[0] != '\0') {
122    *offset = static_cast<uintptr_t>(value);
123    return buf;
124  }
125  return "";
126}
127
128//-------------------------------------------------------------------------
129// C++ object creation function.
130//-------------------------------------------------------------------------
131Backtrace* CreatePtraceObj(pid_t pid, pid_t tid, BacktraceMap* map) {
132  return new BacktracePtrace(new UnwindPtrace(), pid, tid, map);
133}
134