libunwindstack/Elf.cpp - platform/system/core - Gitiles

 /*
  * Copyright (C) 2016 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.
  */

 #include <elf.h>
 #include <string.h>

 #include <memory>
 #include <mutex>
 #include <string>
 #include <utility>

 #define LOG_TAG "unwind"
 #include <log/log.h>

 #include <unwindstack/Elf.h>
 #include <unwindstack/ElfInterface.h>
 #include <unwindstack/MapInfo.h>
 #include <unwindstack/Memory.h>
 #include <unwindstack/Regs.h>

 #include "ElfInterfaceArm.h"
 #include "Symbols.h"

 namespace unwindstack {

 bool Elf::cache_enabled_;
 std::unordered_map<std::string, std::pair<std::shared_ptr<Elf>, bool>>* Elf::cache_;
 std::mutex* Elf::cache_lock_;

 bool Elf::Init(bool init_gnu_debugdata) {
   load_bias_ = 0;
   if (!memory_) {
     return false;
   }

   interface_.reset(CreateInterfaceFromMemory(memory_.get()));
   if (!interface_) {
     return false;
   }

   valid_ = interface_->Init(&load_bias_);
   if (valid_) {
     interface_->InitHeaders();
     if (init_gnu_debugdata) {
       InitGnuDebugdata();
     } else {
       gnu_debugdata_interface_.reset(nullptr);
     }
   } else {
     interface_.reset(nullptr);
   }
   return valid_;
 }

 // It is expensive to initialize the .gnu_debugdata section. Provide a method
 // to initialize this data separately.
 void Elf::InitGnuDebugdata() {
   if (!valid_ || interface_->gnu_debugdata_offset() == 0) {
     return;
   }

   gnu_debugdata_memory_.reset(interface_->CreateGnuDebugdataMemory());
   gnu_debugdata_interface_.reset(CreateInterfaceFromMemory(gnu_debugdata_memory_.get()));
   ElfInterface* gnu = gnu_debugdata_interface_.get();
   if (gnu == nullptr) {
     return;
   }

   // Ignore the load_bias from the compressed section, the correct load bias
   // is in the uncompressed data.
   uint64_t load_bias;
   if (gnu->Init(&load_bias)) {
     gnu->InitHeaders();
     interface_->SetGnuDebugdataInterface(gnu);
   } else {
     // Free all of the memory associated with the gnu_debugdata section.
     gnu_debugdata_memory_.reset(nullptr);
     gnu_debugdata_interface_.reset(nullptr);
   }
 }

 bool Elf::GetSoname(std::string* name) {
   std::lock_guard<std::mutex> guard(lock_);
   return valid_ && interface_->GetSoname(name);
 }

 uint64_t Elf::GetRelPc(uint64_t pc, const MapInfo* map_info) {
   return pc - map_info->start + load_bias_ + map_info->elf_offset;
 }

 bool Elf::GetFunctionName(uint64_t addr, std::string* name, uint64_t* func_offset) {
   std::lock_guard<std::mutex> guard(lock_);
   return valid_ && (interface_->GetFunctionName(addr, load_bias_, name, func_offset) ||
                     (gnu_debugdata_interface_ && gnu_debugdata_interface_->GetFunctionName(
                                                      addr, load_bias_, name, func_offset)));
 }

 bool Elf::GetGlobalVariable(const std::string& name, uint64_t* memory_address) {
   if (!valid_) {
     return false;
   }

   if (!interface_->GetGlobalVariable(name, memory_address) &&
       (gnu_debugdata_interface_ == nullptr ||
        !gnu_debugdata_interface_->GetGlobalVariable(name, memory_address))) {
     return false;
   }

   // Adjust by the load bias.
   if (*memory_address < load_bias_) {
     return false;
   }

   *memory_address -= load_bias_;

   // If this winds up in the dynamic section, then we might need to adjust
   // the address.
   uint64_t dynamic_end = interface_->dynamic_vaddr() + interface_->dynamic_size();
   if (*memory_address >= interface_->dynamic_vaddr() && *memory_address < dynamic_end) {
     if (interface_->dynamic_vaddr() > interface_->dynamic_offset()) {
       *memory_address -= interface_->dynamic_vaddr() - interface_->dynamic_offset();
     } else {
       *memory_address += interface_->dynamic_offset() - interface_->dynamic_vaddr();
     }
   }
   return true;
 }

 void Elf::GetLastError(ErrorData* data) {
   if (valid_) {
     *data = interface_->last_error();
   }
 }

 ErrorCode Elf::GetLastErrorCode() {
   if (valid_) {
     return interface_->LastErrorCode();
   }
   return ERROR_NONE;
 }

 uint64_t Elf::GetLastErrorAddress() {
   if (valid_) {
     return interface_->LastErrorAddress();
   }
   return 0;
 }

 // The relative pc is always relative to the start of the map from which it comes.
 bool Elf::Step(uint64_t rel_pc, uint64_t adjusted_rel_pc, Regs* regs, Memory* process_memory,
                bool* finished) {
   if (!valid_) {
     return false;
   }

   // The relative pc expectd by StepIfSignalHandler is relative to the start of the elf.
   if (regs->StepIfSignalHandler(rel_pc, this, process_memory)) {
     *finished = false;
     return true;
   }

   // Lock during the step which can update information in the object.
   std::lock_guard<std::mutex> guard(lock_);
   return interface_->Step(adjusted_rel_pc, load_bias_, regs, process_memory, finished);
 }

 bool Elf::IsValidElf(Memory* memory) {
   if (memory == nullptr) {
     return false;
   }

   // Verify that this is a valid elf file.
   uint8_t e_ident[SELFMAG + 1];
   if (!memory->ReadFully(0, e_ident, SELFMAG)) {
     return false;
   }

   if (memcmp(e_ident, ELFMAG, SELFMAG) != 0) {
     return false;
   }
   return true;
 }

 void Elf::GetInfo(Memory* memory, bool* valid, uint64_t* size) {
   if (!IsValidElf(memory)) {
     *valid = false;
     return;
   }
   *size = 0;
   *valid = true;

   // Now read the section header information.
   uint8_t class_type;
   if (!memory->ReadFully(EI_CLASS, &class_type, 1)) {
     return;
   }
   if (class_type == ELFCLASS32) {
     ElfInterface32::GetMaxSize(memory, size);
   } else if (class_type == ELFCLASS64) {
     ElfInterface64::GetMaxSize(memory, size);
   } else {
     *valid = false;
   }
 }

 bool Elf::IsValidPc(uint64_t pc) {
   if (!valid_ || pc < load_bias_) {
     return false;
   }
   pc -= load_bias_;

   if (interface_->IsValidPc(pc)) {
     return true;
   }

   if (gnu_debugdata_interface_ != nullptr && gnu_debugdata_interface_->IsValidPc(pc)) {
     return true;
   }

   return false;
 }

 ElfInterface* Elf::CreateInterfaceFromMemory(Memory* memory) {
   if (!IsValidElf(memory)) {
     return nullptr;
   }

   std::unique_ptr<ElfInterface> interface;
   if (!memory->ReadFully(EI_CLASS, &class_type_, 1)) {
     return nullptr;
   }
   if (class_type_ == ELFCLASS32) {
     Elf32_Half e_machine;
     if (!memory->ReadFully(EI_NIDENT + sizeof(Elf32_Half), &e_machine, sizeof(e_machine))) {
       return nullptr;
     }

     machine_type_ = e_machine;
     if (e_machine == EM_ARM) {
       arch_ = ARCH_ARM;
       interface.reset(new ElfInterfaceArm(memory));
     } else if (e_machine == EM_386) {
       arch_ = ARCH_X86;
       interface.reset(new ElfInterface32(memory));
     } else if (e_machine == EM_MIPS) {
       arch_ = ARCH_MIPS;
       interface.reset(new ElfInterface32(memory));
     } else {
       // Unsupported.
       ALOGI("32 bit elf that is neither arm nor x86 nor mips: e_machine = %d\n", e_machine);
       return nullptr;
     }
   } else if (class_type_ == ELFCLASS64) {
     Elf64_Half e_machine;
     if (!memory->ReadFully(EI_NIDENT + sizeof(Elf64_Half), &e_machine, sizeof(e_machine))) {
       return nullptr;
     }

     machine_type_ = e_machine;
     if (e_machine == EM_AARCH64) {
       arch_ = ARCH_ARM64;
     } else if (e_machine == EM_X86_64) {
       arch_ = ARCH_X86_64;
     } else if (e_machine == EM_MIPS) {
       arch_ = ARCH_MIPS64;
     } else {
       // Unsupported.
       ALOGI("64 bit elf that is neither aarch64 nor x86_64 nor mips64: e_machine = %d\n",
             e_machine);
       return nullptr;
     }
     interface.reset(new ElfInterface64(memory));
   }

   return interface.release();
 }

 uint64_t Elf::GetLoadBias(Memory* memory) {
   if (!IsValidElf(memory)) {
     return 0;
   }

   uint8_t class_type;
   if (!memory->Read(EI_CLASS, &class_type, 1)) {
     return 0;
   }

   if (class_type == ELFCLASS32) {
     return ElfInterface::GetLoadBias<Elf32_Ehdr, Elf32_Phdr>(memory);
   } else if (class_type == ELFCLASS64) {
     return ElfInterface::GetLoadBias<Elf64_Ehdr, Elf64_Phdr>(memory);
   }
   return 0;
 }

 void Elf::SetCachingEnabled(bool enable) {
   if (!cache_enabled_ && enable) {
     cache_enabled_ = true;
     cache_ = new std::unordered_map<std::string, std::pair<std::shared_ptr<Elf>, bool>>;
     cache_lock_ = new std::mutex;
   } else if (cache_enabled_ && !enable) {
     cache_enabled_ = false;
     delete cache_;
     delete cache_lock_;
   }
 }

 void Elf::CacheLock() {
   cache_lock_->lock();
 }

 void Elf::CacheUnlock() {
   cache_lock_->unlock();
 }

 void Elf::CacheAdd(MapInfo* info) {
   // If elf_offset != 0, then cache both name:offset and name.
   // The cached name is used to do lookups if multiple maps for the same
   // named elf file exist.
   // For example, if there are two maps boot.odex:1000 and boot.odex:2000
   // where each reference the entire boot.odex, the cache will properly
   // use the same cached elf object.

   if (info->offset == 0 || info->elf_offset != 0) {
     (*cache_)[info->name] = std::make_pair(info->elf, true);
   }

   if (info->offset != 0) {
     // The second element in the pair indicates whether elf_offset should
     // be set to offset when getting out of the cache.
     (*cache_)[info->name + ':' + std::to_string(info->offset)] =
         std::make_pair(info->elf, info->elf_offset != 0);
   }
 }

 bool Elf::CacheAfterCreateMemory(MapInfo* info) {
   if (info->name.empty() || info->offset == 0 || info->elf_offset == 0) {
     return false;
   }

   auto entry = cache_->find(info->name);
   if (entry == cache_->end()) {
     return false;
   }

   // In this case, the whole file is the elf, and the name has already
   // been cached. Add an entry at name:offset to get this directly out
   // of the cache next time.
   info->elf = entry->second.first;
   (*cache_)[info->name + ':' + std::to_string(info->offset)] = std::make_pair(info->elf, true);
   return true;
 }

 bool Elf::CacheGet(MapInfo* info) {
   std::string name(info->name);
   if (info->offset != 0) {
     name += ':' + std::to_string(info->offset);
   }
   auto entry = cache_->find(name);
   if (entry != cache_->end()) {
     info->elf = entry->second.first;
     if (entry->second.second) {
       info->elf_offset = info->offset;
     }
     return true;
   }
   return false;
 }

 }  // namespace unwindstack
	/*
	* Copyright (C) 2016 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.
	*/

	#include <elf.h>
	#include <string.h>

	#include <memory>
	#include <mutex>
	#include <string>
	#include <utility>

	#define LOG_TAG "unwind"
	#include <log/log.h>

	#include <unwindstack/Elf.h>
	#include <unwindstack/ElfInterface.h>
	#include <unwindstack/MapInfo.h>
	#include <unwindstack/Memory.h>
	#include <unwindstack/Regs.h>

	#include "ElfInterfaceArm.h"
	#include "Symbols.h"

	namespace unwindstack {

	bool Elf::cache_enabled_;
	std::unordered_map<std::string, std::pair<std::shared_ptr<Elf>, bool>>* Elf::cache_;
	std::mutex* Elf::cache_lock_;

	bool Elf::Init(bool init_gnu_debugdata) {
	load_bias_ = 0;
	if (!memory_) {
	return false;
	}

	interface_.reset(CreateInterfaceFromMemory(memory_.get()));
	if (!interface_) {
	return false;
	}

	valid_ = interface_->Init(&load_bias_);
	if (valid_) {
	interface_->InitHeaders();
	if (init_gnu_debugdata) {
	InitGnuDebugdata();
	} else {
	gnu_debugdata_interface_.reset(nullptr);
	}
	} else {
	interface_.reset(nullptr);
	}
	return valid_;
	}

	// It is expensive to initialize the .gnu_debugdata section. Provide a method
	// to initialize this data separately.
	void Elf::InitGnuDebugdata() {
	if (!valid_ \|\| interface_->gnu_debugdata_offset() == 0) {
	return;
	}

	gnu_debugdata_memory_.reset(interface_->CreateGnuDebugdataMemory());
	gnu_debugdata_interface_.reset(CreateInterfaceFromMemory(gnu_debugdata_memory_.get()));
	ElfInterface* gnu = gnu_debugdata_interface_.get();
	if (gnu == nullptr) {
	return;
	}

	// Ignore the load_bias from the compressed section, the correct load bias
	// is in the uncompressed data.
	uint64_t load_bias;
	if (gnu->Init(&load_bias)) {
	gnu->InitHeaders();
	interface_->SetGnuDebugdataInterface(gnu);
	} else {
	// Free all of the memory associated with the gnu_debugdata section.
	gnu_debugdata_memory_.reset(nullptr);
	gnu_debugdata_interface_.reset(nullptr);
	}
	}

	bool Elf::GetSoname(std::string* name) {
	std::lock_guard<std::mutex> guard(lock_);
	return valid_ && interface_->GetSoname(name);
	}

	uint64_t Elf::GetRelPc(uint64_t pc, const MapInfo* map_info) {
	return pc - map_info->start + load_bias_ + map_info->elf_offset;
	}

	bool Elf::GetFunctionName(uint64_t addr, std::string* name, uint64_t* func_offset) {
	std::lock_guard<std::mutex> guard(lock_);
	return valid_ && (interface_->GetFunctionName(addr, load_bias_, name, func_offset) \|\|
	(gnu_debugdata_interface_ && gnu_debugdata_interface_->GetFunctionName(
	addr, load_bias_, name, func_offset)));
	}

	bool Elf::GetGlobalVariable(const std::string& name, uint64_t* memory_address) {
	if (!valid_) {
	return false;
	}

	if (!interface_->GetGlobalVariable(name, memory_address) &&
	(gnu_debugdata_interface_ == nullptr \|\|
	!gnu_debugdata_interface_->GetGlobalVariable(name, memory_address))) {
	return false;
	}

	// Adjust by the load bias.
	if (*memory_address < load_bias_) {
	return false;
	}

	*memory_address -= load_bias_;

	// If this winds up in the dynamic section, then we might need to adjust
	// the address.
	uint64_t dynamic_end = interface_->dynamic_vaddr() + interface_->dynamic_size();
	if (memory_address >= interface_->dynamic_vaddr() && memory_address < dynamic_end) {
	if (interface_->dynamic_vaddr() > interface_->dynamic_offset()) {
	*memory_address -= interface_->dynamic_vaddr() - interface_->dynamic_offset();
	} else {
	*memory_address += interface_->dynamic_offset() - interface_->dynamic_vaddr();
	}
	}
	return true;
	}

	void Elf::GetLastError(ErrorData* data) {
	if (valid_) {
	*data = interface_->last_error();
	}
	}

	ErrorCode Elf::GetLastErrorCode() {
	if (valid_) {
	return interface_->LastErrorCode();
	}
	return ERROR_NONE;
	}

	uint64_t Elf::GetLastErrorAddress() {
	if (valid_) {
	return interface_->LastErrorAddress();
	}
	return 0;
	}

	// The relative pc is always relative to the start of the map from which it comes.
	bool Elf::Step(uint64_t rel_pc, uint64_t adjusted_rel_pc, Regs* regs, Memory* process_memory,
	bool* finished) {
	if (!valid_) {
	return false;
	}

	// The relative pc expectd by StepIfSignalHandler is relative to the start of the elf.
	if (regs->StepIfSignalHandler(rel_pc, this, process_memory)) {
	*finished = false;
	return true;
	}

	// Lock during the step which can update information in the object.
	std::lock_guard<std::mutex> guard(lock_);
	return interface_->Step(adjusted_rel_pc, load_bias_, regs, process_memory, finished);
	}

	bool Elf::IsValidElf(Memory* memory) {
	if (memory == nullptr) {
	return false;
	}

	// Verify that this is a valid elf file.
	uint8_t e_ident[SELFMAG + 1];
	if (!memory->ReadFully(0, e_ident, SELFMAG)) {
	return false;
	}

	if (memcmp(e_ident, ELFMAG, SELFMAG) != 0) {
	return false;
	}
	return true;
	}

	void Elf::GetInfo(Memory* memory, bool* valid, uint64_t* size) {
	if (!IsValidElf(memory)) {
	*valid = false;
	return;
	}
	*size = 0;
	*valid = true;

	// Now read the section header information.
	uint8_t class_type;
	if (!memory->ReadFully(EI_CLASS, &class_type, 1)) {
	return;
	}
	if (class_type == ELFCLASS32) {
	ElfInterface32::GetMaxSize(memory, size);
	} else if (class_type == ELFCLASS64) {
	ElfInterface64::GetMaxSize(memory, size);
	} else {
	*valid = false;
	}
	}

	bool Elf::IsValidPc(uint64_t pc) {
	if (!valid_ \|\| pc < load_bias_) {
	return false;
	}
	pc -= load_bias_;

	if (interface_->IsValidPc(pc)) {
	return true;
	}

	if (gnu_debugdata_interface_ != nullptr && gnu_debugdata_interface_->IsValidPc(pc)) {
	return true;
	}

	return false;
	}

	ElfInterface* Elf::CreateInterfaceFromMemory(Memory* memory) {
	if (!IsValidElf(memory)) {
	return nullptr;
	}

	std::unique_ptr<ElfInterface> interface;
	if (!memory->ReadFully(EI_CLASS, &class_type_, 1)) {
	return nullptr;
	}
	if (class_type_ == ELFCLASS32) {
	Elf32_Half e_machine;
	if (!memory->ReadFully(EI_NIDENT + sizeof(Elf32_Half), &e_machine, sizeof(e_machine))) {
	return nullptr;
	}

	machine_type_ = e_machine;
	if (e_machine == EM_ARM) {
	arch_ = ARCH_ARM;
	interface.reset(new ElfInterfaceArm(memory));
	} else if (e_machine == EM_386) {
	arch_ = ARCH_X86;
	interface.reset(new ElfInterface32(memory));
	} else if (e_machine == EM_MIPS) {
	arch_ = ARCH_MIPS;
	interface.reset(new ElfInterface32(memory));
	} else {
	// Unsupported.
	ALOGI("32 bit elf that is neither arm nor x86 nor mips: e_machine = %d\n", e_machine);
	return nullptr;
	}
	} else if (class_type_ == ELFCLASS64) {
	Elf64_Half e_machine;
	if (!memory->ReadFully(EI_NIDENT + sizeof(Elf64_Half), &e_machine, sizeof(e_machine))) {
	return nullptr;
	}

	machine_type_ = e_machine;
	if (e_machine == EM_AARCH64) {
	arch_ = ARCH_ARM64;
	} else if (e_machine == EM_X86_64) {
	arch_ = ARCH_X86_64;
	} else if (e_machine == EM_MIPS) {
	arch_ = ARCH_MIPS64;
	} else {
	// Unsupported.
	ALOGI("64 bit elf that is neither aarch64 nor x86_64 nor mips64: e_machine = %d\n",
	e_machine);
	return nullptr;
	}
	interface.reset(new ElfInterface64(memory));
	}

	return interface.release();
	}

	uint64_t Elf::GetLoadBias(Memory* memory) {
	if (!IsValidElf(memory)) {
	return 0;
	}

	uint8_t class_type;
	if (!memory->Read(EI_CLASS, &class_type, 1)) {
	return 0;
	}

	if (class_type == ELFCLASS32) {
	return ElfInterface::GetLoadBias<Elf32_Ehdr, Elf32_Phdr>(memory);
	} else if (class_type == ELFCLASS64) {
	return ElfInterface::GetLoadBias<Elf64_Ehdr, Elf64_Phdr>(memory);
	}
	return 0;
	}

	void Elf::SetCachingEnabled(bool enable) {
	if (!cache_enabled_ && enable) {
	cache_enabled_ = true;
	cache_ = new std::unordered_map<std::string, std::pair<std::shared_ptr<Elf>, bool>>;
	cache_lock_ = new std::mutex;
	} else if (cache_enabled_ && !enable) {
	cache_enabled_ = false;
	delete cache_;
	delete cache_lock_;
	}
	}

	void Elf::CacheLock() {
	cache_lock_->lock();
	}

	void Elf::CacheUnlock() {
	cache_lock_->unlock();
	}

	void Elf::CacheAdd(MapInfo* info) {
	// If elf_offset != 0, then cache both name:offset and name.
	// The cached name is used to do lookups if multiple maps for the same
	// named elf file exist.
	// For example, if there are two maps boot.odex:1000 and boot.odex:2000
	// where each reference the entire boot.odex, the cache will properly
	// use the same cached elf object.

	if (info->offset == 0 \|\| info->elf_offset != 0) {
	(*cache_)[info->name] = std::make_pair(info->elf, true);
	}

	if (info->offset != 0) {
	// The second element in the pair indicates whether elf_offset should
	// be set to offset when getting out of the cache.
	(*cache_)[info->name + ':' + std::to_string(info->offset)] =
	std::make_pair(info->elf, info->elf_offset != 0);
	}
	}

	bool Elf::CacheAfterCreateMemory(MapInfo* info) {
	if (info->name.empty() \|\| info->offset == 0 \|\| info->elf_offset == 0) {
	return false;
	}

	auto entry = cache_->find(info->name);
	if (entry == cache_->end()) {
	return false;
	}

	// In this case, the whole file is the elf, and the name has already
	// been cached. Add an entry at name:offset to get this directly out
	// of the cache next time.
	info->elf = entry->second.first;
	(*cache_)[info->name + ':' + std::to_string(info->offset)] = std::make_pair(info->elf, true);
	return true;
	}

	bool Elf::CacheGet(MapInfo* info) {
	std::string name(info->name);
	if (info->offset != 0) {
	name += ':' + std::to_string(info->offset);
	}
	auto entry = cache_->find(name);
	if (entry != cache_->end()) {
	info->elf = entry->second.first;
	if (entry->second.second) {
	info->elf_offset = info->offset;
	}
	return true;
	}
	return false;
	}

	} // namespace unwindstack