UnwindCurrent.cpp revision 20303f856f1f1cdb5af58af0b116b8c598f0ea5c 
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 <cutils/log.h>
22
23#include <backtrace/backtrace.h>
24
25#define UNW_LOCAL_ONLY
26#include <libunwind.h>
27
28#include "UnwindCurrent.h"
29
30// Define the ucontext_t structures needed for each supported arch.
31#if defined(__arm__)
32  // The current version of the <signal.h> doesn't define ucontext_t.
33  #include <asm/sigcontext.h> // Ensure 'struct sigcontext' is defined.
34
35  // Machine context at the time a signal was raised.
36  typedef struct ucontext {
37    uint32_t uc_flags;
38    struct ucontext* uc_link;
39    stack_t uc_stack;
40    struct sigcontext uc_mcontext;
41    uint32_t uc_sigmask;
42  } ucontext_t;
43#elif defined(__i386__)
44  #include <asm/sigcontext.h>
45  #include <asm/ucontext.h>
46  typedef struct ucontext ucontext_t;
47#elif !defined(__mips__)
48  #error Unsupported architecture.
49#endif
50
51//-------------------------------------------------------------------------
52// UnwindCurrent functions.
53//-------------------------------------------------------------------------
54UnwindCurrent::UnwindCurrent() {
55}
56
57UnwindCurrent::~UnwindCurrent() {
58}
59
60bool UnwindCurrent::Unwind(size_t num_ignore_frames) {
61  int ret = unw_getcontext(&context_);
62  if (ret < 0) {
63    BACK_LOGW("unw_getcontext failed %d", ret);
64    return false;
65  }
66  return UnwindFromContext(num_ignore_frames, true);
67}
68
69std::string UnwindCurrent::GetFunctionNameRaw(uintptr_t pc, uintptr_t* offset) {
70  *offset = 0;
71  char buf[512];
72  unw_word_t value;
73  if (unw_get_proc_name_by_ip(unw_local_addr_space, pc, buf, sizeof(buf),
74                              &value, &context_) >= 0 && buf[0] != '\0') {
75    *offset = static_cast<uintptr_t>(value);
76    return buf;
77  }
78  return "";
79}
80
81bool UnwindCurrent::UnwindFromContext(size_t num_ignore_frames, bool resolve) {
82  backtrace_t* backtrace = GetBacktraceData();
83  backtrace->num_frames = 0;
84
85  // The cursor structure is pretty large, do not put it on the stack.
86  unw_cursor_t* cursor = new unw_cursor_t;
87  int ret = unw_init_local(cursor, &context_);
88  if (ret < 0) {
89    BACK_LOGW("unw_init_local failed %d", ret);
90    delete cursor;
91    return false;
92  }
93
94  do {
95    unw_word_t pc;
96    ret = unw_get_reg(cursor, UNW_REG_IP, &pc);
97    if (ret < 0) {
98      BACK_LOGW("Failed to read IP %d", ret);
99      break;
100    }
101    unw_word_t sp;
102    ret = unw_get_reg(cursor, UNW_REG_SP, &sp);
103    if (ret < 0) {
104      BACK_LOGW("Failed to read SP %d", ret);
105      break;
106    }
107
108    if (num_ignore_frames == 0) {
109      size_t num_frames = backtrace->num_frames;
110      backtrace_frame_data_t* frame = &backtrace->frames[num_frames];
111      frame->num = num_frames;
112      frame->pc = static_cast<uintptr_t>(pc);
113      frame->sp = static_cast<uintptr_t>(sp);
114      frame->stack_size = 0;
115      frame->map_name = NULL;
116      frame->map_offset = 0;
117      frame->func_name = NULL;
118      frame->func_offset = 0;
119
120      if (num_frames > 0) {
121        // Set the stack size for the previous frame.
122        backtrace_frame_data_t* prev = &backtrace->frames[num_frames-1];
123        prev->stack_size = frame->sp - prev->sp;
124      }
125
126      if (resolve) {
127        std::string func_name = backtrace_obj_->GetFunctionName(frame->pc, &frame->func_offset);
128        if (!func_name.empty()) {
129          frame->func_name = strdup(func_name.c_str());
130        }
131
132        uintptr_t map_start;
133        frame->map_name = backtrace_obj_->GetMapName(frame->pc, &map_start);
134        if (frame->map_name) {
135          frame->map_offset = frame->pc - map_start;
136        }
137      }
138
139      backtrace->num_frames++;
140    } else {
141      num_ignore_frames--;
142    }
143    ret = unw_step (cursor);
144  } while (ret > 0 && backtrace->num_frames < MAX_BACKTRACE_FRAMES);
145
146  delete cursor;
147  return true;
148}
149
150void UnwindCurrent::ExtractContext(void* sigcontext) {
151  unw_tdep_context_t* context = reinterpret_cast<unw_tdep_context_t*>(&context_);
152  const ucontext_t* uc = reinterpret_cast<const ucontext_t*>(sigcontext);
153
154#if defined(__arm__)
155  context->regs[0] = uc->uc_mcontext.arm_r0;
156  context->regs[1] = uc->uc_mcontext.arm_r1;
157  context->regs[2] = uc->uc_mcontext.arm_r2;
158  context->regs[3] = uc->uc_mcontext.arm_r3;
159  context->regs[4] = uc->uc_mcontext.arm_r4;
160  context->regs[5] = uc->uc_mcontext.arm_r5;
161  context->regs[6] = uc->uc_mcontext.arm_r6;
162  context->regs[7] = uc->uc_mcontext.arm_r7;
163  context->regs[8] = uc->uc_mcontext.arm_r8;
164  context->regs[9] = uc->uc_mcontext.arm_r9;
165  context->regs[10] = uc->uc_mcontext.arm_r10;
166  context->regs[11] = uc->uc_mcontext.arm_fp;
167  context->regs[12] = uc->uc_mcontext.arm_ip;
168  context->regs[13] = uc->uc_mcontext.arm_sp;
169  context->regs[14] = uc->uc_mcontext.arm_lr;
170  context->regs[15] = uc->uc_mcontext.arm_pc;
171#elif defined(__mips__) || defined(__i386__)
172  context->uc_mcontext = uc->uc_mcontext;
173#endif
174}
175
176//-------------------------------------------------------------------------
177// UnwindThread functions.
178//-------------------------------------------------------------------------
179UnwindThread::UnwindThread() {
180}
181
182UnwindThread::~UnwindThread() {
183}
184
185bool UnwindThread::Init() {
186  return true;
187}
188
189void UnwindThread::ThreadUnwind(
190    siginfo_t* /*siginfo*/, void* sigcontext, size_t num_ignore_frames) {
191  ExtractContext(sigcontext);
192  UnwindFromContext(num_ignore_frames, false);
193}
194
195//-------------------------------------------------------------------------
196// C++ object creation function.
197//-------------------------------------------------------------------------
198Backtrace* CreateCurrentObj(backtrace_map_info_t* map_info) {
199  return new BacktraceCurrent(new UnwindCurrent(), map_info);
200}
201
202Backtrace* CreateThreadObj(pid_t tid, backtrace_map_info_t* map_info) {
203  UnwindThread* thread_obj = new UnwindThread();
204  return new BacktraceThread(thread_obj, thread_obj, tid, map_info);
205}
206