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 31 UnwindPtrace::UnwindPtrace(pid_t pid, pid_t tid, BacktraceMap* map) 32 : BacktracePtrace(pid, tid, map), addr_space_(nullptr), upt_info_(nullptr) { 33 } 34 35 UnwindPtrace::~UnwindPtrace() { 36 if (upt_info_) { 37 _UPT_destroy(upt_info_); 38 upt_info_ = nullptr; 39 } 40 41 if (addr_space_) { 42 // Remove the map from the address space before destroying it. 43 // It will be freed in the UnwindMap destructor. 44 unw_map_set(addr_space_, nullptr); 45 46 unw_destroy_addr_space(addr_space_); 47 addr_space_ = nullptr; 48 } 49 } 50 51 bool UnwindPtrace::Init() { 52 if (upt_info_) { 53 return true; 54 } 55 56 if (addr_space_) { 57 // If somehow the addr_space_ gets initialized but upt_info_ doesn't, 58 // then that indicates there is some kind of failure. 59 return false; 60 } 61 62 addr_space_ = unw_create_addr_space(&_UPT_accessors, 0); 63 if (!addr_space_) { 64 BACK_LOGW("unw_create_addr_space failed."); 65 error_ = BACKTRACE_UNWIND_ERROR_SETUP_FAILED; 66 return false; 67 } 68 69 UnwindMap* map = static_cast<UnwindMap*>(GetMap()); 70 unw_map_set(addr_space_, map->GetMapCursor()); 71 72 upt_info_ = reinterpret_cast<struct UPT_info*>(_UPT_create(Tid())); 73 if (!upt_info_) { 74 BACK_LOGW("Failed to create upt info."); 75 error_ = BACKTRACE_UNWIND_ERROR_SETUP_FAILED; 76 return false; 77 } 78 79 return true; 80 } 81 82 bool UnwindPtrace::Unwind(size_t num_ignore_frames, ucontext_t* ucontext) { 83 if (GetMap() == nullptr) { 84 // Without a map object, we can't do anything. 85 error_ = BACKTRACE_UNWIND_ERROR_MAP_MISSING; 86 return false; 87 } 88 89 error_ = BACKTRACE_UNWIND_NO_ERROR; 90 91 if (ucontext) { 92 BACK_LOGW("Unwinding from a specified context not supported yet."); 93 error_ = BACKTRACE_UNWIND_ERROR_UNSUPPORTED_OPERATION; 94 return false; 95 } 96 97 if (!Init()) { 98 return false; 99 } 100 101 unw_cursor_t cursor; 102 int ret = unw_init_remote(&cursor, addr_space_, upt_info_); 103 if (ret < 0) { 104 BACK_LOGW("unw_init_remote failed %d", ret); 105 error_ = BACKTRACE_UNWIND_ERROR_SETUP_FAILED; 106 return false; 107 } 108 109 size_t num_frames = 0; 110 do { 111 unw_word_t pc; 112 ret = unw_get_reg(&cursor, UNW_REG_IP, &pc); 113 if (ret < 0) { 114 BACK_LOGW("Failed to read IP %d", ret); 115 break; 116 } 117 unw_word_t sp; 118 ret = unw_get_reg(&cursor, UNW_REG_SP, &sp); 119 if (ret < 0) { 120 BACK_LOGW("Failed to read SP %d", ret); 121 break; 122 } 123 124 if (num_ignore_frames == 0) { 125 frames_.resize(num_frames+1); 126 backtrace_frame_data_t* frame = &frames_.at(num_frames); 127 frame->num = num_frames; 128 frame->pc = static_cast<uintptr_t>(pc); 129 frame->sp = static_cast<uintptr_t>(sp); 130 frame->stack_size = 0; 131 132 if (num_frames > 0) { 133 backtrace_frame_data_t* prev = &frames_.at(num_frames-1); 134 prev->stack_size = frame->sp - prev->sp; 135 } 136 137 FillInMap(frame->pc, &frame->map); 138 139 frame->func_name = GetFunctionName(frame->pc, &frame->func_offset, &frame->map); 140 141 num_frames++; 142 // If the pc is in a device map, then don't try to step. 143 if (frame->map.flags & PROT_DEVICE_MAP) { 144 break; 145 } 146 } else { 147 // If the pc is in a device map, then don't try to step. 148 backtrace_map_t map; 149 FillInMap(pc, &map); 150 if (map.flags & PROT_DEVICE_MAP) { 151 break; 152 } 153 num_ignore_frames--; 154 } 155 // Verify the sp is not in a device map. 156 backtrace_map_t map; 157 FillInMap(sp, &map); 158 if (map.flags & PROT_DEVICE_MAP) { 159 break; 160 } 161 ret = unw_step (&cursor); 162 } while (ret > 0 && num_frames < MAX_BACKTRACE_FRAMES); 163 164 return true; 165 } 166 167 std::string UnwindPtrace::GetFunctionNameRaw(uintptr_t pc, uintptr_t* offset) { 168 if (!Init()) { 169 return ""; 170 } 171 172 *offset = 0; 173 char buf[512]; 174 unw_word_t value; 175 if (unw_get_proc_name_by_ip(addr_space_, pc, buf, sizeof(buf), &value, 176 upt_info_) >= 0 && buf[0] != '\0') { 177 *offset = static_cast<uintptr_t>(value); 178 return buf; 179 } 180 return ""; 181 } 182
