UnwindCurrent.cpp revision c6c194ced095df5e777b8fa24527ebd29c8fef54 
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/ucontext.h>
20#include <sys/types.h>
21
22#include <backtrace/Backtrace.h>
23#include <backtrace/BacktraceMap.h>
24
25#define UNW_LOCAL_ONLY
26#include <libunwind.h>
27
28#include "UnwindCurrent.h"
29#include "UnwindMap.h"
30
31//-------------------------------------------------------------------------
32// UnwindCurrent functions.
33//-------------------------------------------------------------------------
34UnwindCurrent::UnwindCurrent() {
35}
36
37UnwindCurrent::~UnwindCurrent() {
38}
39
40bool UnwindCurrent::Unwind(size_t num_ignore_frames) {
41  int ret = unw_getcontext(&context_);
42  if (ret < 0) {
43    BACK_LOGW("unw_getcontext failed %d", ret);
44    return false;
45  }
46  return UnwindFromContext(num_ignore_frames, true);
47}
48
49std::string UnwindCurrent::GetFunctionNameRaw(uintptr_t pc, uintptr_t* offset) {
50  *offset = 0;
51  char buf[512];
52  unw_word_t value;
53  if (unw_get_proc_name_by_ip(unw_local_addr_space, pc, buf, sizeof(buf),
54                              &value, &context_) >= 0 && buf[0] != '\0') {
55    *offset = static_cast<uintptr_t>(value);
56    return buf;
57  }
58  return "";
59}
60
61bool UnwindCurrent::UnwindFromContext(size_t num_ignore_frames, bool resolve) {
62  // The cursor structure is pretty large, do not put it on the stack.
63  unw_cursor_t* cursor = new unw_cursor_t;
64  int ret = unw_init_local(cursor, &context_);
65  if (ret < 0) {
66    BACK_LOGW("unw_init_local failed %d", ret);
67    delete cursor;
68    return false;
69  }
70
71  std::vector<backtrace_frame_data_t>* frames = GetFrames();
72  frames->reserve(MAX_BACKTRACE_FRAMES);
73  size_t num_frames = 0;
74  do {
75    unw_word_t pc;
76    ret = unw_get_reg(cursor, UNW_REG_IP, &pc);
77    if (ret < 0) {
78      BACK_LOGW("Failed to read IP %d", ret);
79      break;
80    }
81    unw_word_t sp;
82    ret = unw_get_reg(cursor, UNW_REG_SP, &sp);
83    if (ret < 0) {
84      BACK_LOGW("Failed to read SP %d", ret);
85      break;
86    }
87
88    if (num_ignore_frames == 0) {
89      frames->resize(num_frames+1);
90      backtrace_frame_data_t* frame = &frames->at(num_frames);
91      frame->num = num_frames;
92      frame->pc = static_cast<uintptr_t>(pc);
93      frame->sp = static_cast<uintptr_t>(sp);
94      frame->stack_size = 0;
95
96      if (num_frames > 0) {
97        // Set the stack size for the previous frame.
98        backtrace_frame_data_t* prev = &frames->at(num_frames-1);
99        prev->stack_size = frame->sp - prev->sp;
100      }
101
102      if (resolve) {
103        frame->func_name = GetFunctionName(frame->pc, &frame->func_offset);
104        frame->map = FindMap(frame->pc);
105      } else {
106        frame->map = NULL;
107        frame->func_offset = 0;
108      }
109      num_frames++;
110    } else {
111      num_ignore_frames--;
112    }
113    ret = unw_step (cursor);
114  } while (ret > 0 && num_frames < MAX_BACKTRACE_FRAMES);
115
116  delete cursor;
117  return true;
118}
119
120void UnwindCurrent::ExtractContext(void* sigcontext) {
121  unw_tdep_context_t* context = reinterpret_cast<unw_tdep_context_t*>(&context_);
122  const ucontext_t* uc = reinterpret_cast<const ucontext_t*>(sigcontext);
123
124#if defined(__arm__)
125  context->regs[0] = uc->uc_mcontext.arm_r0;
126  context->regs[1] = uc->uc_mcontext.arm_r1;
127  context->regs[2] = uc->uc_mcontext.arm_r2;
128  context->regs[3] = uc->uc_mcontext.arm_r3;
129  context->regs[4] = uc->uc_mcontext.arm_r4;
130  context->regs[5] = uc->uc_mcontext.arm_r5;
131  context->regs[6] = uc->uc_mcontext.arm_r6;
132  context->regs[7] = uc->uc_mcontext.arm_r7;
133  context->regs[8] = uc->uc_mcontext.arm_r8;
134  context->regs[9] = uc->uc_mcontext.arm_r9;
135  context->regs[10] = uc->uc_mcontext.arm_r10;
136  context->regs[11] = uc->uc_mcontext.arm_fp;
137  context->regs[12] = uc->uc_mcontext.arm_ip;
138  context->regs[13] = uc->uc_mcontext.arm_sp;
139  context->regs[14] = uc->uc_mcontext.arm_lr;
140  context->regs[15] = uc->uc_mcontext.arm_pc;
141#else
142  context->uc_mcontext = uc->uc_mcontext;
143#endif
144}
145
146//-------------------------------------------------------------------------
147// UnwindThread functions.
148//-------------------------------------------------------------------------
149UnwindThread::UnwindThread() {
150}
151
152UnwindThread::~UnwindThread() {
153}
154
155void UnwindThread::ThreadUnwind(
156    siginfo_t* /*siginfo*/, void* sigcontext, size_t num_ignore_frames) {
157  ExtractContext(sigcontext);
158  UnwindFromContext(num_ignore_frames, false);
159}
160
161//-------------------------------------------------------------------------
162// C++ object creation function.
163//-------------------------------------------------------------------------
164Backtrace* CreateCurrentObj(BacktraceMap* map) {
165  return new BacktraceCurrent(new UnwindCurrent(), map);
166}
167
168Backtrace* CreateThreadObj(pid_t tid, BacktraceMap* map) {
169  UnwindThread* thread_obj = new UnwindThread();
170  return new BacktraceThread(thread_obj, thread_obj, tid, map);
171}
172