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 31 std::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 43 void 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 68 bool 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
