libunwindstack/Unwinder.cpp - android_system_core - Gitiles

 /*
  * Copyright (C) 2017 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 #define _GNU_SOURCE 1
 #include <elf.h>
 #include <inttypes.h>
 #include <stdint.h>
 #include <string.h>
 #include <sys/types.h>
 #include <unistd.h>

 #include <algorithm>

 #include <android-base/stringprintf.h>
 #include <android-base/strings.h>

 #include <unwindstack/Elf.h>
 #include <unwindstack/JitDebug.h>
 #include <unwindstack/MapInfo.h>
 #include <unwindstack/Maps.h>
 #include <unwindstack/Memory.h>
 #include <unwindstack/Unwinder.h>

 #include <unwindstack/DexFiles.h>

 // Use the demangler from libc++.
 extern "C" char* __cxa_demangle(const char*, char*, size_t*, int* status);

 namespace unwindstack {

 // Inject extra 'virtual' frame that represents the dex pc data.
 // The dex pc is a magic register defined in the Mterp interpreter,
 // and thus it will be restored/observed in the frame after it.
 // Adding the dex frame first here will create something like:
 //   #7 pc 0015fa20 core.vdex   java.util.Arrays.binarySearch+8
 //   #8 pc 006b1ba1 libartd.so  ExecuteMterpImpl+14625
 //   #9 pc 0039a1ef libartd.so  art::interpreter::Execute+719
 void Unwinder::FillInDexFrame() {
   size_t frame_num = frames_.size();
   frames_.resize(frame_num + 1);
   FrameData* frame = &frames_.at(frame_num);
   frame->num = frame_num;

   uint64_t dex_pc = regs_->dex_pc();
   frame->pc = dex_pc;
   frame->sp = regs_->sp();

   MapInfo* info = maps_->Find(dex_pc);
   if (info != nullptr) {
     frame->map_start = info->start;
     frame->map_end = info->end;
     // Since this is a dex file frame, the elf_start_offset is not set
     // by any of the normal code paths. Use the offset of the map since
     // that matches the actual offset.
     frame->map_elf_start_offset = info->offset;
     frame->map_exact_offset = info->offset;
     frame->map_load_bias = info->load_bias;
     frame->map_flags = info->flags;
     if (resolve_names_) {
       frame->map_name = info->name;
     }
     frame->rel_pc = dex_pc - info->start;
   } else {
     frame->rel_pc = dex_pc;
     return;
   }

   if (!resolve_names_) {
     return;
   }

 #if defined(DEXFILE_SUPPORT)
   if (dex_files_ == nullptr) {
     return;
   }

   dex_files_->GetMethodInformation(maps_, info, dex_pc, &frame->function_name,
                                    &frame->function_offset);
 #endif
 }

 FrameData* Unwinder::FillInFrame(MapInfo* map_info, Elf* elf, uint64_t rel_pc,
                                  uint64_t pc_adjustment) {
   size_t frame_num = frames_.size();
   frames_.resize(frame_num + 1);
   FrameData* frame = &frames_.at(frame_num);
   frame->num = frame_num;
   frame->sp = regs_->sp();
   frame->rel_pc = rel_pc - pc_adjustment;
   frame->pc = regs_->pc() - pc_adjustment;

   if (map_info == nullptr) {
     // Nothing else to update.
     return nullptr;
   }

   if (resolve_names_) {
     frame->map_name = map_info->name;
     if (embedded_soname_ && map_info->elf_start_offset != 0 && !frame->map_name.empty()) {
       std::string soname = elf->GetSoname();
       if (!soname.empty()) {
         frame->map_name += '!' + soname;
       }
     }
   }
   frame->map_elf_start_offset = map_info->elf_start_offset;
   frame->map_exact_offset = map_info->offset;
   frame->map_start = map_info->start;
   frame->map_end = map_info->end;
   frame->map_flags = map_info->flags;
   frame->map_load_bias = elf->GetLoadBias();
   return frame;
 }

 static bool ShouldStop(const std::vector<std::string>* map_suffixes_to_ignore,
                        std::string& map_name) {
   if (map_suffixes_to_ignore == nullptr) {
     return false;
   }
   auto pos = map_name.find_last_of('.');
   if (pos == std::string::npos) {
     return false;
   }

   return std::find(map_suffixes_to_ignore->begin(), map_suffixes_to_ignore->end(),
                    map_name.substr(pos + 1)) != map_suffixes_to_ignore->end();
 }

 void Unwinder::Unwind(const std::vector<std::string>* initial_map_names_to_skip,
                       const std::vector<std::string>* map_suffixes_to_ignore) {
   frames_.clear();
   last_error_.code = ERROR_NONE;
   last_error_.address = 0;
   elf_from_memory_not_file_ = false;

   ArchEnum arch = regs_->Arch();

   bool return_address_attempt = false;
   bool adjust_pc = false;
   for (; frames_.size() < max_frames_;) {
     uint64_t cur_pc = regs_->pc();
     uint64_t cur_sp = regs_->sp();

     MapInfo* map_info = maps_->Find(regs_->pc());
     uint64_t pc_adjustment = 0;
     uint64_t step_pc;
     uint64_t rel_pc;
     Elf* elf;
     if (map_info == nullptr) {
       step_pc = regs_->pc();
       rel_pc = step_pc;
       last_error_.code = ERROR_INVALID_MAP;
     } else {
       if (ShouldStop(map_suffixes_to_ignore, map_info->name)) {
         break;
       }
       elf = map_info->GetElf(process_memory_, arch);
       // If this elf is memory backed, and there is a valid file, then set
       // an indicator that we couldn't open the file.
       if (!elf_from_memory_not_file_ && map_info->memory_backed_elf && !map_info->name.empty() &&
           map_info->name[0] != '[' && !android::base::StartsWith(map_info->name, "/memfd:")) {
         elf_from_memory_not_file_ = true;
       }
       step_pc = regs_->pc();
       rel_pc = elf->GetRelPc(step_pc, map_info);
       // Everyone except elf data in gdb jit debug maps uses the relative pc.
       if (!(map_info->flags & MAPS_FLAGS_JIT_SYMFILE_MAP)) {
         step_pc = rel_pc;
       }
       if (adjust_pc) {
         pc_adjustment = regs_->GetPcAdjustment(rel_pc, elf);
       } else {
         pc_adjustment = 0;
       }
       step_pc -= pc_adjustment;

       // If the pc is in an invalid elf file, try and get an Elf object
       // using the jit debug information.
       if (!elf->valid() && jit_debug_ != nullptr) {
         uint64_t adjusted_jit_pc = regs_->pc() - pc_adjustment;
         Elf* jit_elf = jit_debug_->GetElf(maps_, adjusted_jit_pc);
         if (jit_elf != nullptr) {
           // The jit debug information requires a non relative adjusted pc.
           step_pc = adjusted_jit_pc;
           elf = jit_elf;
         }
       }
     }

     FrameData* frame = nullptr;
     if (map_info == nullptr || initial_map_names_to_skip == nullptr ||
         std::find(initial_map_names_to_skip->begin(), initial_map_names_to_skip->end(),
                   basename(map_info->name.c_str())) == initial_map_names_to_skip->end()) {
       if (regs_->dex_pc() != 0) {
         // Add a frame to represent the dex file.
         FillInDexFrame();
         // Clear the dex pc so that we don't repeat this frame later.
         regs_->set_dex_pc(0);

         // Make sure there is enough room for the real frame.
         if (frames_.size() == max_frames_) {
           last_error_.code = ERROR_MAX_FRAMES_EXCEEDED;
           break;
         }
       }

       frame = FillInFrame(map_info, elf, rel_pc, pc_adjustment);

       // Once a frame is added, stop skipping frames.
       initial_map_names_to_skip = nullptr;
     }
     adjust_pc = true;

     bool stepped = false;
     bool in_device_map = false;
     bool finished = false;
     if (map_info != nullptr) {
       if (map_info->flags & MAPS_FLAGS_DEVICE_MAP) {
         // Do not stop here, fall through in case we are
         // in the speculative unwind path and need to remove
         // some of the speculative frames.
         in_device_map = true;
       } else {
         MapInfo* sp_info = maps_->Find(regs_->sp());
         if (sp_info != nullptr && sp_info->flags & MAPS_FLAGS_DEVICE_MAP) {
           // Do not stop here, fall through in case we are
           // in the speculative unwind path and need to remove
           // some of the speculative frames.
           in_device_map = true;
         } else {
           if (elf->StepIfSignalHandler(rel_pc, regs_, process_memory_.get())) {
             stepped = true;
             if (frame != nullptr) {
               // Need to adjust the relative pc because the signal handler
               // pc should not be adjusted.
               frame->rel_pc = rel_pc;
               frame->pc += pc_adjustment;
               step_pc = rel_pc;
             }
           } else if (elf->Step(step_pc, regs_, process_memory_.get(), &finished)) {
             stepped = true;
           }
           elf->GetLastError(&last_error_);
         }
       }
     }

     if (frame != nullptr) {
       if (!resolve_names_ ||
           !elf->GetFunctionName(step_pc, &frame->function_name, &frame->function_offset)) {
         frame->function_name = "";
         frame->function_offset = 0;
       }
     }

     if (finished) {
       break;
     }

     if (!stepped) {
       if (return_address_attempt) {
         // Only remove the speculative frame if there are more than two frames
         // or the pc in the first frame is in a valid map.
         // This allows for a case where the code jumps into the middle of
         // nowhere, but there is no other unwind information after that.
         if (frames_.size() > 2 || (frames_.size() > 0 && maps_->Find(frames_[0].pc) != nullptr)) {
           // Remove the speculative frame.
           frames_.pop_back();
         }
         break;
       } else if (in_device_map) {
         // Do not attempt any other unwinding, pc or sp is in a device
         // map.
         break;
       } else {
         // Steping didn't work, try this secondary method.
         if (!regs_->SetPcFromReturnAddress(process_memory_.get())) {
           break;
         }
         return_address_attempt = true;
       }
     } else {
       return_address_attempt = false;
       if (max_frames_ == frames_.size()) {
         last_error_.code = ERROR_MAX_FRAMES_EXCEEDED;
       }
     }

     // If the pc and sp didn't change, then consider everything stopped.
     if (cur_pc == regs_->pc() && cur_sp == regs_->sp()) {
       last_error_.code = ERROR_REPEATED_FRAME;
       break;
     }
   }
 }

 std::string Unwinder::FormatFrame(const FrameData& frame) const {
   std::string data;
   if (regs_->Is32Bit()) {
     data += android::base::StringPrintf("  #%02zu pc %08" PRIx64, frame.num, frame.rel_pc);
   } else {
     data += android::base::StringPrintf("  #%02zu pc %016" PRIx64, frame.num, frame.rel_pc);
   }

   if (frame.map_start == frame.map_end) {
     // No valid map associated with this frame.
     data += "  <unknown>";
   } else if (!frame.map_name.empty()) {
     data += "  " + frame.map_name;
   } else {
     data += android::base::StringPrintf("  <anonymous:%" PRIx64 ">", frame.map_start);
   }

   if (frame.map_elf_start_offset != 0) {
     data += android::base::StringPrintf(" (offset 0x%" PRIx64 ")", frame.map_elf_start_offset);
   }

   if (!frame.function_name.empty()) {
     char* demangled_name = __cxa_demangle(frame.function_name.c_str(), nullptr, nullptr, nullptr);
     if (demangled_name == nullptr) {
       data += " (" + frame.function_name;
     } else {
       data += " (";
       data += demangled_name;
       free(demangled_name);
     }
     if (frame.function_offset != 0) {
       data += android::base::StringPrintf("+%" PRId64, frame.function_offset);
     }
     data += ')';
   }

   MapInfo* map_info = maps_->Find(frame.map_start);
   if (map_info != nullptr && display_build_id_) {
     std::string build_id = map_info->GetPrintableBuildID();
     if (!build_id.empty()) {
       data += " (BuildId: " + build_id + ')';
     }
   }
   return data;
 }

 std::string Unwinder::FormatFrame(size_t frame_num) const {
   if (frame_num >= frames_.size()) {
     return "";
   }
   return FormatFrame(frames_[frame_num]);
 }

 void Unwinder::SetJitDebug(JitDebug* jit_debug, ArchEnum arch) {
   jit_debug->SetArch(arch);
   jit_debug_ = jit_debug;
 }

 void Unwinder::SetDexFiles(DexFiles* dex_files, ArchEnum arch) {
   dex_files->SetArch(arch);
   dex_files_ = dex_files;
 }

 bool UnwinderFromPid::Init(ArchEnum arch) {
   if (pid_ == getpid()) {
     maps_ptr_.reset(new LocalMaps());
   } else {
     maps_ptr_.reset(new RemoteMaps(pid_));
   }
   if (!maps_ptr_->Parse()) {
     return false;
   }
   maps_ = maps_ptr_.get();

   process_memory_ = Memory::CreateProcessMemoryCached(pid_);

   jit_debug_ptr_.reset(new JitDebug(process_memory_));
   jit_debug_ = jit_debug_ptr_.get();
   SetJitDebug(jit_debug_, arch);
 #if defined(DEXFILE_SUPPORT)
   dex_files_ptr_.reset(new DexFiles(process_memory_));
   dex_files_ = dex_files_ptr_.get();
   SetDexFiles(dex_files_, arch);
 #endif

   return true;
 }

 }  // namespace unwindstack
	/*
	* Copyright (C) 2017 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	#define _GNU_SOURCE 1
	#include <elf.h>
	#include <inttypes.h>
	#include <stdint.h>
	#include <string.h>
	#include <sys/types.h>
	#include <unistd.h>

	#include <algorithm>

	#include <android-base/stringprintf.h>
	#include <android-base/strings.h>

	#include <unwindstack/Elf.h>
	#include <unwindstack/JitDebug.h>
	#include <unwindstack/MapInfo.h>
	#include <unwindstack/Maps.h>
	#include <unwindstack/Memory.h>
	#include <unwindstack/Unwinder.h>

	#include <unwindstack/DexFiles.h>

	// Use the demangler from libc++.
	extern "C" char* __cxa_demangle(const char, char, size_t, int status);

	namespace unwindstack {

	// Inject extra 'virtual' frame that represents the dex pc data.
	// The dex pc is a magic register defined in the Mterp interpreter,
	// and thus it will be restored/observed in the frame after it.
	// Adding the dex frame first here will create something like:
	// #7 pc 0015fa20 core.vdex java.util.Arrays.binarySearch+8
	// #8 pc 006b1ba1 libartd.so ExecuteMterpImpl+14625
	// #9 pc 0039a1ef libartd.so art::interpreter::Execute+719
	void Unwinder::FillInDexFrame() {
	size_t frame_num = frames_.size();
	frames_.resize(frame_num + 1);
	FrameData* frame = &frames_.at(frame_num);
	frame->num = frame_num;

	uint64_t dex_pc = regs_->dex_pc();
	frame->pc = dex_pc;
	frame->sp = regs_->sp();

	MapInfo* info = maps_->Find(dex_pc);
	if (info != nullptr) {
	frame->map_start = info->start;
	frame->map_end = info->end;
	// Since this is a dex file frame, the elf_start_offset is not set
	// by any of the normal code paths. Use the offset of the map since
	// that matches the actual offset.
	frame->map_elf_start_offset = info->offset;
	frame->map_exact_offset = info->offset;
	frame->map_load_bias = info->load_bias;
	frame->map_flags = info->flags;
	if (resolve_names_) {
	frame->map_name = info->name;
	}
	frame->rel_pc = dex_pc - info->start;
	} else {
	frame->rel_pc = dex_pc;
	return;
	}

	if (!resolve_names_) {
	return;
	}

	#if defined(DEXFILE_SUPPORT)
	if (dex_files_ == nullptr) {
	return;
	}

	dex_files_->GetMethodInformation(maps_, info, dex_pc, &frame->function_name,
	&frame->function_offset);
	#endif
	}

	FrameData* Unwinder::FillInFrame(MapInfo* map_info, Elf* elf, uint64_t rel_pc,
	uint64_t pc_adjustment) {
	size_t frame_num = frames_.size();
	frames_.resize(frame_num + 1);
	FrameData* frame = &frames_.at(frame_num);
	frame->num = frame_num;
	frame->sp = regs_->sp();
	frame->rel_pc = rel_pc - pc_adjustment;
	frame->pc = regs_->pc() - pc_adjustment;

	if (map_info == nullptr) {
	// Nothing else to update.
	return nullptr;
	}

	if (resolve_names_) {
	frame->map_name = map_info->name;
	if (embedded_soname_ && map_info->elf_start_offset != 0 && !frame->map_name.empty()) {
	std::string soname = elf->GetSoname();
	if (!soname.empty()) {
	frame->map_name += '!' + soname;
	}
	}
	}
	frame->map_elf_start_offset = map_info->elf_start_offset;
	frame->map_exact_offset = map_info->offset;
	frame->map_start = map_info->start;
	frame->map_end = map_info->end;
	frame->map_flags = map_info->flags;
	frame->map_load_bias = elf->GetLoadBias();
	return frame;
	}

	static bool ShouldStop(const std::vector<std::string>* map_suffixes_to_ignore,
	std::string& map_name) {
	if (map_suffixes_to_ignore == nullptr) {
	return false;
	}
	auto pos = map_name.find_last_of('.');
	if (pos == std::string::npos) {
	return false;
	}

	return std::find(map_suffixes_to_ignore->begin(), map_suffixes_to_ignore->end(),
	map_name.substr(pos + 1)) != map_suffixes_to_ignore->end();
	}

	void Unwinder::Unwind(const std::vector<std::string>* initial_map_names_to_skip,
	const std::vector<std::string>* map_suffixes_to_ignore) {
	frames_.clear();
	last_error_.code = ERROR_NONE;
	last_error_.address = 0;
	elf_from_memory_not_file_ = false;

	ArchEnum arch = regs_->Arch();

	bool return_address_attempt = false;
	bool adjust_pc = false;
	for (; frames_.size() < max_frames_;) {
	uint64_t cur_pc = regs_->pc();
	uint64_t cur_sp = regs_->sp();

	MapInfo* map_info = maps_->Find(regs_->pc());
	uint64_t pc_adjustment = 0;
	uint64_t step_pc;
	uint64_t rel_pc;
	Elf* elf;
	if (map_info == nullptr) {
	step_pc = regs_->pc();
	rel_pc = step_pc;
	last_error_.code = ERROR_INVALID_MAP;
	} else {
	if (ShouldStop(map_suffixes_to_ignore, map_info->name)) {
	break;
	}
	elf = map_info->GetElf(process_memory_, arch);
	// If this elf is memory backed, and there is a valid file, then set
	// an indicator that we couldn't open the file.
	if (!elf_from_memory_not_file_ && map_info->memory_backed_elf && !map_info->name.empty() &&
	map_info->name[0] != '[' && !android::base::StartsWith(map_info->name, "/memfd:")) {
	elf_from_memory_not_file_ = true;
	}
	step_pc = regs_->pc();
	rel_pc = elf->GetRelPc(step_pc, map_info);
	// Everyone except elf data in gdb jit debug maps uses the relative pc.
	if (!(map_info->flags & MAPS_FLAGS_JIT_SYMFILE_MAP)) {
	step_pc = rel_pc;
	}
	if (adjust_pc) {
	pc_adjustment = regs_->GetPcAdjustment(rel_pc, elf);
	} else {
	pc_adjustment = 0;
	}
	step_pc -= pc_adjustment;

	// If the pc is in an invalid elf file, try and get an Elf object
	// using the jit debug information.
	if (!elf->valid() && jit_debug_ != nullptr) {
	uint64_t adjusted_jit_pc = regs_->pc() - pc_adjustment;
	Elf* jit_elf = jit_debug_->GetElf(maps_, adjusted_jit_pc);
	if (jit_elf != nullptr) {
	// The jit debug information requires a non relative adjusted pc.
	step_pc = adjusted_jit_pc;
	elf = jit_elf;
	}
	}
	}

	FrameData* frame = nullptr;
	if (map_info == nullptr \|\| initial_map_names_to_skip == nullptr \|\|
	std::find(initial_map_names_to_skip->begin(), initial_map_names_to_skip->end(),
	basename(map_info->name.c_str())) == initial_map_names_to_skip->end()) {
	if (regs_->dex_pc() != 0) {
	// Add a frame to represent the dex file.
	FillInDexFrame();
	// Clear the dex pc so that we don't repeat this frame later.
	regs_->set_dex_pc(0);

	// Make sure there is enough room for the real frame.
	if (frames_.size() == max_frames_) {
	last_error_.code = ERROR_MAX_FRAMES_EXCEEDED;
	break;
	}
	}

	frame = FillInFrame(map_info, elf, rel_pc, pc_adjustment);

	// Once a frame is added, stop skipping frames.
	initial_map_names_to_skip = nullptr;
	}
	adjust_pc = true;

	bool stepped = false;
	bool in_device_map = false;
	bool finished = false;
	if (map_info != nullptr) {
	if (map_info->flags & MAPS_FLAGS_DEVICE_MAP) {
	// Do not stop here, fall through in case we are
	// in the speculative unwind path and need to remove
	// some of the speculative frames.
	in_device_map = true;
	} else {
	MapInfo* sp_info = maps_->Find(regs_->sp());
	if (sp_info != nullptr && sp_info->flags & MAPS_FLAGS_DEVICE_MAP) {
	// Do not stop here, fall through in case we are
	// in the speculative unwind path and need to remove
	// some of the speculative frames.
	in_device_map = true;
	} else {
	if (elf->StepIfSignalHandler(rel_pc, regs_, process_memory_.get())) {
	stepped = true;
	if (frame != nullptr) {
	// Need to adjust the relative pc because the signal handler
	// pc should not be adjusted.
	frame->rel_pc = rel_pc;
	frame->pc += pc_adjustment;
	step_pc = rel_pc;
	}
	} else if (elf->Step(step_pc, regs_, process_memory_.get(), &finished)) {
	stepped = true;
	}
	elf->GetLastError(&last_error_);
	}
	}
	}

	if (frame != nullptr) {
	if (!resolve_names_ \|\|
	!elf->GetFunctionName(step_pc, &frame->function_name, &frame->function_offset)) {
	frame->function_name = "";
	frame->function_offset = 0;
	}
	}

	if (finished) {
	break;
	}

	if (!stepped) {
	if (return_address_attempt) {
	// Only remove the speculative frame if there are more than two frames
	// or the pc in the first frame is in a valid map.
	// This allows for a case where the code jumps into the middle of
	// nowhere, but there is no other unwind information after that.
	if (frames_.size() > 2 \|\| (frames_.size() > 0 && maps_->Find(frames_[0].pc) != nullptr)) {
	// Remove the speculative frame.
	frames_.pop_back();
	}
	break;
	} else if (in_device_map) {
	// Do not attempt any other unwinding, pc or sp is in a device
	// map.
	break;
	} else {
	// Steping didn't work, try this secondary method.
	if (!regs_->SetPcFromReturnAddress(process_memory_.get())) {
	break;
	}
	return_address_attempt = true;
	}
	} else {
	return_address_attempt = false;
	if (max_frames_ == frames_.size()) {
	last_error_.code = ERROR_MAX_FRAMES_EXCEEDED;
	}
	}

	// If the pc and sp didn't change, then consider everything stopped.
	if (cur_pc == regs_->pc() && cur_sp == regs_->sp()) {
	last_error_.code = ERROR_REPEATED_FRAME;
	break;
	}
	}
	}

	std::string Unwinder::FormatFrame(const FrameData& frame) const {
	std::string data;
	if (regs_->Is32Bit()) {
	data += android::base::StringPrintf(" #%02zu pc %08" PRIx64, frame.num, frame.rel_pc);
	} else {
	data += android::base::StringPrintf(" #%02zu pc %016" PRIx64, frame.num, frame.rel_pc);
	}

	if (frame.map_start == frame.map_end) {
	// No valid map associated with this frame.
	data += " <unknown>";
	} else if (!frame.map_name.empty()) {
	data += " " + frame.map_name;
	} else {
	data += android::base::StringPrintf(" <anonymous:%" PRIx64 ">", frame.map_start);
	}

	if (frame.map_elf_start_offset != 0) {
	data += android::base::StringPrintf(" (offset 0x%" PRIx64 ")", frame.map_elf_start_offset);
	}

	if (!frame.function_name.empty()) {
	char* demangled_name = __cxa_demangle(frame.function_name.c_str(), nullptr, nullptr, nullptr);
	if (demangled_name == nullptr) {
	data += " (" + frame.function_name;
	} else {
	data += " (";
	data += demangled_name;
	free(demangled_name);
	}
	if (frame.function_offset != 0) {
	data += android::base::StringPrintf("+%" PRId64, frame.function_offset);
	}
	data += ')';
	}

	MapInfo* map_info = maps_->Find(frame.map_start);
	if (map_info != nullptr && display_build_id_) {
	std::string build_id = map_info->GetPrintableBuildID();
	if (!build_id.empty()) {
	data += " (BuildId: " + build_id + ')';
	}
	}
	return data;
	}

	std::string Unwinder::FormatFrame(size_t frame_num) const {
	if (frame_num >= frames_.size()) {
	return "";
	}
	return FormatFrame(frames_[frame_num]);
	}

	void Unwinder::SetJitDebug(JitDebug* jit_debug, ArchEnum arch) {
	jit_debug->SetArch(arch);
	jit_debug_ = jit_debug;
	}

	void Unwinder::SetDexFiles(DexFiles* dex_files, ArchEnum arch) {
	dex_files->SetArch(arch);
	dex_files_ = dex_files;
	}

	bool UnwinderFromPid::Init(ArchEnum arch) {
	if (pid_ == getpid()) {
	maps_ptr_.reset(new LocalMaps());
	} else {
	maps_ptr_.reset(new RemoteMaps(pid_));
	}
	if (!maps_ptr_->Parse()) {
	return false;
	}
	maps_ = maps_ptr_.get();

	process_memory_ = Memory::CreateProcessMemoryCached(pid_);

	jit_debug_ptr_.reset(new JitDebug(process_memory_));
	jit_debug_ = jit_debug_ptr_.get();
	SetJitDebug(jit_debug_, arch);
	#if defined(DEXFILE_SUPPORT)
	dex_files_ptr_.reset(new DexFiles(process_memory_));
	dex_files_ = dex_files_ptr_.get();
	SetDexFiles(dex_files_, arch);
	#endif

	return true;
	}

	} // namespace unwindstack