UnwindCurrent.cpp revision c463ba45c42b4e2d8ce30c02a626d7183102f46e 
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 <ucontext.h>
19
20#include <memory>
21#include <string>
22
23#define UNW_LOCAL_ONLY
24#include <libunwind.h>
25
26#include <backtrace/Backtrace.h>
27
28#include "BacktraceLog.h"
29#include "UnwindCurrent.h"
30
31std::string UnwindCurrent::GetFunctionNameRaw(uintptr_t pc, uintptr_t* offset) {
32  *offset = 0;
33  char buf[512];
34  unw_word_t value;
35  if (unw_get_proc_name_by_ip(unw_local_addr_space, pc, buf, sizeof(buf),
36                              &value, &context_) >= 0 && buf[0] != '\0') {
37    *offset = static_cast<uintptr_t>(value);
38    return buf;
39  }
40  return "";
41}
42
43void UnwindCurrent::GetUnwContextFromUcontext(const ucontext_t* ucontext) {
44  unw_tdep_context_t* unw_context = reinterpret_cast<unw_tdep_context_t*>(&context_);
45
46#if defined(__arm__)
47  unw_context->regs[0] = ucontext->uc_mcontext.arm_r0;
48  unw_context->regs[1] = ucontext->uc_mcontext.arm_r1;
49  unw_context->regs[2] = ucontext->uc_mcontext.arm_r2;
50  unw_context->regs[3] = ucontext->uc_mcontext.arm_r3;
51  unw_context->regs[4] = ucontext->uc_mcontext.arm_r4;
52  unw_context->regs[5] = ucontext->uc_mcontext.arm_r5;
53  unw_context->regs[6] = ucontext->uc_mcontext.arm_r6;
54  unw_context->regs[7] = ucontext->uc_mcontext.arm_r7;
55  unw_context->regs[8] = ucontext->uc_mcontext.arm_r8;
56  unw_context->regs[9] = ucontext->uc_mcontext.arm_r9;
57  unw_context->regs[10] = ucontext->uc_mcontext.arm_r10;
58  unw_context->regs[11] = ucontext->uc_mcontext.arm_fp;
59  unw_context->regs[12] = ucontext->uc_mcontext.arm_ip;
60  unw_context->regs[13] = ucontext->uc_mcontext.arm_sp;
61  unw_context->regs[14] = ucontext->uc_mcontext.arm_lr;
62  unw_context->regs[15] = ucontext->uc_mcontext.arm_pc;
63#else
64  unw_context->uc_mcontext = ucontext->uc_mcontext;
65#endif
66}
67
68bool UnwindCurrent::UnwindFromContext(size_t num_ignore_frames, ucontext_t* ucontext) {
69  if (ucontext == nullptr) {
70    int ret = unw_getcontext(&context_);
71    if (ret < 0) {
72      BACK_LOGW("unw_getcontext failed %d", ret);
73      error_ = BACKTRACE_UNWIND_ERROR_SETUP_FAILED;
74      return false;
75    }
76  } else {
77    GetUnwContextFromUcontext(ucontext);
78  }
79
80  // The cursor structure is pretty large, do not put it on the stack.
81  std::unique_ptr<unw_cursor_t> cursor(new unw_cursor_t);
82  int ret = unw_init_local(cursor.get(), &context_);
83  if (ret < 0) {
84    BACK_LOGW("unw_init_local failed %d", ret);
85    error_ = BACKTRACE_UNWIND_ERROR_SETUP_FAILED;
86    return false;
87  }
88
89  size_t num_frames = 0;
90  do {
91    unw_word_t pc;
92    ret = unw_get_reg(cursor.get(), UNW_REG_IP, &pc);
93    if (ret < 0) {
94      BACK_LOGW("Failed to read IP %d", ret);
95      break;
96    }
97    unw_word_t sp;
98    ret = unw_get_reg(cursor.get(), UNW_REG_SP, &sp);
99    if (ret < 0) {
100      BACK_LOGW("Failed to read SP %d", ret);
101      break;
102    }
103
104    frames_.resize(num_frames+1);
105    backtrace_frame_data_t* frame = &frames_.at(num_frames);
106    frame->num = num_frames;
107    frame->pc = static_cast<uintptr_t>(pc);
108    frame->sp = static_cast<uintptr_t>(sp);
109    frame->stack_size = 0;
110
111    FillInMap(frame->pc, &frame->map);
112    // Check to see if we should skip this frame because it's coming
113    // from within the library, and we are doing a local unwind.
114    if (ucontext != nullptr || num_frames != 0 || !DiscardFrame(*frame)) {
115      if (num_ignore_frames == 0) {
116        // GetFunctionName is an expensive call, only do it if we are
117        // keeping the frame.
118        frame->func_name = GetFunctionName(frame->pc, &frame->func_offset);
119        if (num_frames > 0) {
120          // Set the stack size for the previous frame.
121          backtrace_frame_data_t* prev = &frames_.at(num_frames-1);
122          prev->stack_size = frame->sp - prev->sp;
123        }
124        num_frames++;
125      } else {
126        num_ignore_frames--;
127      }
128    }
129    ret = unw_step (cursor.get());
130  } while (ret > 0 && num_frames < MAX_BACKTRACE_FRAMES);
131
132  return true;
133}
134