UnwindCurrent.cpp revision 46756821c4fe238f12a6e5ea18c356398f8d8795 
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 <sys/types.h>
20
21#include <backtrace/Backtrace.h>
22#include <backtrace/BacktraceMap.h>
23
24#define UNW_LOCAL_ONLY
25#include <libunwind.h>
26
27#include "UnwindCurrent.h"
28
29// Define the ucontext_t structures needed for each supported arch.
30#if defined(__arm__)
31  // The current version of the <signal.h> doesn't define ucontext_t.
32  #include <asm/sigcontext.h> // Ensure 'struct sigcontext' is defined.
33
34  // Machine context at the time a signal was raised.
35  typedef struct ucontext {
36    uint32_t uc_flags;
37    struct ucontext* uc_link;
38    stack_t uc_stack;
39    struct sigcontext uc_mcontext;
40    uint32_t uc_sigmask;
41  } ucontext_t;
42#elif defined(__i386__)
43  #include <asm/sigcontext.h>
44  #include <asm/ucontext.h>
45  typedef struct ucontext ucontext_t;
46#elif !defined(__mips__)
47  #error Unsupported architecture.
48#endif
49
50//-------------------------------------------------------------------------
51// UnwindCurrent functions.
52//-------------------------------------------------------------------------
53UnwindCurrent::UnwindCurrent() {
54}
55
56UnwindCurrent::~UnwindCurrent() {
57}
58
59bool UnwindCurrent::Unwind(size_t num_ignore_frames) {
60  int ret = unw_getcontext(&context_);
61  if (ret < 0) {
62    BACK_LOGW("unw_getcontext failed %d", ret);
63    return false;
64  }
65  return UnwindFromContext(num_ignore_frames, true);
66}
67
68std::string UnwindCurrent::GetFunctionNameRaw(uintptr_t pc, uintptr_t* offset) {
69  *offset = 0;
70  char buf[512];
71  unw_word_t value;
72  if (unw_get_proc_name_by_ip(unw_local_addr_space, pc, buf, sizeof(buf),
73                              &value, &context_) >= 0 && buf[0] != '\0') {
74    *offset = static_cast<uintptr_t>(value);
75    return buf;
76  }
77  return "";
78}
79
80bool UnwindCurrent::UnwindFromContext(size_t num_ignore_frames, bool resolve) {
81  // The cursor structure is pretty large, do not put it on the stack.
82  unw_cursor_t* cursor = new unw_cursor_t;
83  int ret = unw_init_local(cursor, &context_);
84  if (ret < 0) {
85    BACK_LOGW("unw_init_local failed %d", ret);
86    delete cursor;
87    return false;
88  }
89
90  std::vector<backtrace_frame_data_t>* frames = GetFrames();
91  frames->reserve(MAX_BACKTRACE_FRAMES);
92  size_t num_frames = 0;
93  do {
94    unw_word_t pc;
95    ret = unw_get_reg(cursor, UNW_REG_IP, &pc);
96    if (ret < 0) {
97      BACK_LOGW("Failed to read IP %d", ret);
98      break;
99    }
100    unw_word_t sp;
101    ret = unw_get_reg(cursor, UNW_REG_SP, &sp);
102    if (ret < 0) {
103      BACK_LOGW("Failed to read SP %d", ret);
104      break;
105    }
106
107    if (num_ignore_frames == 0) {
108      frames->resize(num_frames+1);
109      backtrace_frame_data_t* frame = &frames->at(num_frames);
110      frame->num = num_frames;
111      frame->pc = static_cast<uintptr_t>(pc);
112      frame->sp = static_cast<uintptr_t>(sp);
113      frame->stack_size = 0;
114
115      if (num_frames > 0) {
116        // Set the stack size for the previous frame.
117        backtrace_frame_data_t* prev = &frames->at(num_frames-1);
118        prev->stack_size = frame->sp - prev->sp;
119      }
120
121      if (resolve) {
122        frame->func_name = backtrace_obj_->GetFunctionName(frame->pc, &frame->func_offset);
123        frame->map = backtrace_obj_->FindMap(frame->pc);
124      } else {
125        frame->map = NULL;
126        frame->func_offset = 0;
127      }
128      num_frames++;
129    } else {
130      num_ignore_frames--;
131    }
132    ret = unw_step (cursor);
133  } while (ret > 0 && num_frames < MAX_BACKTRACE_FRAMES);
134
135  delete cursor;
136  return true;
137}
138
139void UnwindCurrent::ExtractContext(void* sigcontext) {
140  unw_tdep_context_t* context = reinterpret_cast<unw_tdep_context_t*>(&context_);
141  const ucontext_t* uc = reinterpret_cast<const ucontext_t*>(sigcontext);
142
143#if defined(__arm__)
144  context->regs[0] = uc->uc_mcontext.arm_r0;
145  context->regs[1] = uc->uc_mcontext.arm_r1;
146  context->regs[2] = uc->uc_mcontext.arm_r2;
147  context->regs[3] = uc->uc_mcontext.arm_r3;
148  context->regs[4] = uc->uc_mcontext.arm_r4;
149  context->regs[5] = uc->uc_mcontext.arm_r5;
150  context->regs[6] = uc->uc_mcontext.arm_r6;
151  context->regs[7] = uc->uc_mcontext.arm_r7;
152  context->regs[8] = uc->uc_mcontext.arm_r8;
153  context->regs[9] = uc->uc_mcontext.arm_r9;
154  context->regs[10] = uc->uc_mcontext.arm_r10;
155  context->regs[11] = uc->uc_mcontext.arm_fp;
156  context->regs[12] = uc->uc_mcontext.arm_ip;
157  context->regs[13] = uc->uc_mcontext.arm_sp;
158  context->regs[14] = uc->uc_mcontext.arm_lr;
159  context->regs[15] = uc->uc_mcontext.arm_pc;
160#elif defined(__mips__) || defined(__i386__)
161  context->uc_mcontext = uc->uc_mcontext;
162#endif
163}
164
165//-------------------------------------------------------------------------
166// UnwindThread functions.
167//-------------------------------------------------------------------------
168UnwindThread::UnwindThread() {
169}
170
171UnwindThread::~UnwindThread() {
172}
173
174bool UnwindThread::Init() {
175  return true;
176}
177
178void UnwindThread::ThreadUnwind(
179    siginfo_t* /*siginfo*/, void* sigcontext, size_t num_ignore_frames) {
180  ExtractContext(sigcontext);
181  UnwindFromContext(num_ignore_frames, false);
182}
183
184//-------------------------------------------------------------------------
185// C++ object creation function.
186//-------------------------------------------------------------------------
187Backtrace* CreateCurrentObj(BacktraceMap* map) {
188  return new BacktraceCurrent(new UnwindCurrent(), map);
189}
190
191Backtrace* CreateThreadObj(pid_t tid, BacktraceMap* map) {
192  UnwindThread* thread_obj = new UnwindThread();
193  return new BacktraceThread(thread_obj, thread_obj, tid, map);
194}
195