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 <stdint.h>
18#include <sys/types.h>
19#include <ucontext.h>
20
21#include <libunwind.h>
22#include <libunwind-ptrace.h>
23
24#include <backtrace/Backtrace.h>
25#include <backtrace/BacktraceMap.h>
26
27#include "BacktraceLog.h"
28#include "UnwindMap.h"
29#include "UnwindPtrace.h"
30
31UnwindPtrace::UnwindPtrace(pid_t pid, pid_t tid, BacktraceMap* map)
32    : BacktracePtrace(pid, tid, map), addr_space_(nullptr), upt_info_(nullptr) {
33}
34
35UnwindPtrace::~UnwindPtrace() {
36  if (upt_info_) {
37    _UPT_destroy(upt_info_);
38    upt_info_ = nullptr;
39  }
40  if (addr_space_) {
41    // Remove the map from the address space before destroying it.
42    // It will be freed in the UnwindMap destructor.
43    unw_map_set(addr_space_, nullptr);
44
45    unw_destroy_addr_space(addr_space_);
46    addr_space_ = nullptr;
47  }
48}
49
50bool UnwindPtrace::Unwind(size_t num_ignore_frames, ucontext_t* ucontext) {
51  if (GetMap() == nullptr) {
52    // Without a map object, we can't do anything.
53    error_ = BACKTRACE_UNWIND_ERROR_MAP_MISSING;
54    return false;
55  }
56
57  error_ = BACKTRACE_UNWIND_NO_ERROR;
58
59  if (ucontext) {
60    BACK_LOGW("Unwinding from a specified context not supported yet.");
61    error_ = BACKTRACE_UNWIND_ERROR_UNSUPPORTED_OPERATION;
62    return false;
63  }
64
65  addr_space_ = unw_create_addr_space(&_UPT_accessors, 0);
66  if (!addr_space_) {
67    BACK_LOGW("unw_create_addr_space failed.");
68    error_ = BACKTRACE_UNWIND_ERROR_SETUP_FAILED;
69    return false;
70  }
71
72  UnwindMap* map = static_cast<UnwindMap*>(GetMap());
73  unw_map_set(addr_space_, map->GetMapCursor());
74
75  upt_info_ = reinterpret_cast<struct UPT_info*>(_UPT_create(Tid()));
76  if (!upt_info_) {
77    BACK_LOGW("Failed to create upt info.");
78    error_ = BACKTRACE_UNWIND_ERROR_SETUP_FAILED;
79    return false;
80  }
81
82  unw_cursor_t cursor;
83  int ret = unw_init_remote(&cursor, addr_space_, upt_info_);
84  if (ret < 0) {
85    BACK_LOGW("unw_init_remote failed %d", ret);
86    error_ = BACKTRACE_UNWIND_ERROR_SETUP_FAILED;
87    return false;
88  }
89
90  size_t num_frames = 0;
91  do {
92    unw_word_t pc;
93    ret = unw_get_reg(&cursor, UNW_REG_IP, &pc);
94    if (ret < 0) {
95      BACK_LOGW("Failed to read IP %d", ret);
96      break;
97    }
98    unw_word_t sp;
99    ret = unw_get_reg(&cursor, UNW_REG_SP, &sp);
100    if (ret < 0) {
101      BACK_LOGW("Failed to read SP %d", ret);
102      break;
103    }
104
105    if (num_ignore_frames == 0) {
106      frames_.resize(num_frames+1);
107      backtrace_frame_data_t* frame = &frames_.at(num_frames);
108      frame->num = num_frames;
109      frame->pc = static_cast<uintptr_t>(pc);
110      frame->sp = static_cast<uintptr_t>(sp);
111      frame->stack_size = 0;
112
113      if (num_frames > 0) {
114        backtrace_frame_data_t* prev = &frames_.at(num_frames-1);
115        prev->stack_size = frame->sp - prev->sp;
116      }
117
118      frame->func_name = GetFunctionName(frame->pc, &frame->func_offset);
119
120      FillInMap(frame->pc, &frame->map);
121
122      num_frames++;
123    } else {
124      num_ignore_frames--;
125    }
126    ret = unw_step (&cursor);
127  } while (ret > 0 && num_frames < MAX_BACKTRACE_FRAMES);
128
129  return true;
130}
131
132std::string UnwindPtrace::GetFunctionNameRaw(uintptr_t pc, uintptr_t* offset) {
133  *offset = 0;
134  char buf[512];
135  unw_word_t value;
136  if (unw_get_proc_name_by_ip(addr_space_, pc, buf, sizeof(buf), &value,
137                              upt_info_) >= 0 && buf[0] != '\0') {
138    *offset = static_cast<uintptr_t>(value);
139    return buf;
140  }
141  return "";
142}
143