/*
 * Copyright (C) 2019 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 "ETMDecoder.h"

#include <sstream>

#include <android-base/expected.h>
#include <android-base/logging.h>
#include <android-base/strings.h>
#include <llvm/Support/MemoryBuffer.h>
#include <opencsd.h>

#include "ETMConstants.h"

namespace simpleperf {
namespace {

class DecoderLogStr : public ocsdMsgLogStrOutI {
 public:
  void printOutStr(const std::string& out_str) override { LOG(DEBUG) << out_str; }
};

class DecodeErrorLogger : public ocsdDefaultErrorLogger {
 public:
  DecodeErrorLogger(const std::function<void(const ocsdError&)>& error_callback)
      : error_callback_(error_callback) {
    initErrorLogger(OCSD_ERR_SEV_INFO, false);
    msg_logger_.setLogOpts(ocsdMsgLogger::OUT_STR_CB);
    msg_logger_.setStrOutFn(&log_str_);
    setOutputLogger(&msg_logger_);
  }

  void LogError(const ocsd_hndl_err_log_t handle, const ocsdError* error) override {
    ocsdDefaultErrorLogger::LogError(handle, error);
    if (error != nullptr) {
      error_callback_(*error);
    }
  }

 private:
  std::function<void(const ocsdError&)> error_callback_;
  DecoderLogStr log_str_;
  ocsdMsgLogger msg_logger_;
};

static bool IsRespError(ocsd_datapath_resp_t resp) {
  return resp >= OCSD_RESP_ERR_CONT;
}

// Used instead of DecodeTree in OpenCSD to avoid linking decoders not for ETMV4 instruction tracing
// in OpenCSD.
class ETMV4IDecodeTree {
 public:
  ETMV4IDecodeTree()
      : error_logger_(std::bind(&ETMV4IDecodeTree::ProcessError, this, std::placeholders::_1)) {
    frame_decoder_.Configure(OCSD_DFRMTR_FRAME_MEM_ALIGN);
    frame_decoder_.getErrLogAttachPt()->attach(&error_logger_);
  }

  bool CreateDecoder(const EtmV4Config* config) {
    uint8_t trace_id = config->getTraceID();
    auto packet_decoder = std::make_unique<TrcPktProcEtmV4I>(trace_id);
    packet_decoder->setProtocolConfig(config);
    packet_decoder->getErrorLogAttachPt()->replace_first(&error_logger_);
    frame_decoder_.getIDStreamAttachPt(trace_id)->attach(packet_decoder.get());
    auto result = packet_decoders_.emplace(trace_id, packet_decoder.release());
    if (!result.second) {
      LOG(ERROR) << "trace id " << trace_id << " has been used";
    }
    return result.second;
  }

  void AttachPacketSink(uint8_t trace_id, IPktDataIn<EtmV4ITrcPacket>& packet_sink) {
    auto& packet_decoder = packet_decoders_[trace_id];
    CHECK(packet_decoder);
    packet_decoder->getPacketOutAttachPt()->replace_first(&packet_sink);
  }

  void AttachPacketMonitor(uint8_t trace_id, IPktRawDataMon<EtmV4ITrcPacket>& packet_monitor) {
    auto& packet_decoder = packet_decoders_[trace_id];
    CHECK(packet_decoder);
    packet_decoder->getRawPacketMonAttachPt()->replace_first(&packet_monitor);
  }

  void AttachRawFramePrinter(RawFramePrinter& frame_printer) {
    frame_decoder_.Configure(frame_decoder_.getConfigFlags() | OCSD_DFRMTR_PACKED_RAW_OUT);
    frame_decoder_.getTrcRawFrameAttachPt()->replace_first(&frame_printer);
  }

  ITrcDataIn& GetFormattedDataIn() { return frame_decoder_; }

  ITrcDataIn& GetUnformattedDataIn(uint8_t trace_id) {
    auto& decoder = packet_decoders_[trace_id];
    CHECK(decoder);
    return *decoder;
  }

  void ProcessError(const ocsdError& error) {
    if (error.getErrorCode() == OCSD_ERR_INVALID_PCKT_HDR) {
      // Found an invalid packet header, following packets for this trace id may also be invalid.
      // So reset the decoder to find I_ASYNC packet in the data stream.
      if (auto it = packet_decoders_.find(error.getErrorChanID()); it != packet_decoders_.end()) {
        auto& packet_decoder = it->second;
        CHECK(packet_decoder);
        packet_decoder->TraceDataIn(OCSD_OP_RESET, error.getErrorIndex(), 0, nullptr, nullptr);
      }
    }
  }

  DecodeErrorLogger& ErrorLogger() { return error_logger_; }

 private:
  DecodeErrorLogger error_logger_;
  TraceFormatterFrameDecoder frame_decoder_;
  std::unordered_map<uint8_t, std::unique_ptr<TrcPktProcEtmV4I>> packet_decoders_;
};

// Similar to IPktDataIn<EtmV4ITrcPacket>, but add trace id.
struct PacketCallback {
  // packet callbacks are called in priority order.
  enum Priority {
    MAP_LOCATOR,
    BRANCH_LIST_PARSER,
    PACKET_TO_ELEMENT,
  };

  PacketCallback(Priority prio) : priority(prio) {}
  virtual ~PacketCallback() {}
  virtual ocsd_datapath_resp_t ProcessPacket(uint8_t trace_id, ocsd_datapath_op_t op,
                                             ocsd_trc_index_t index_sop,
                                             const EtmV4ITrcPacket* pkt) = 0;
  const Priority priority;
};

// Receives packets from a packet decoder in OpenCSD library.
class PacketSink : public IPktDataIn<EtmV4ITrcPacket> {
 public:
  PacketSink(uint8_t trace_id) : trace_id_(trace_id) {}

  void AddCallback(PacketCallback* callback) {
    auto it = std::lower_bound(callbacks_.begin(), callbacks_.end(), callback,
                               [](const PacketCallback* c1, const PacketCallback* c2) {
                                 return c1->priority < c2->priority;
                               });
    callbacks_.insert(it, callback);
  }

  ocsd_datapath_resp_t PacketDataIn(ocsd_datapath_op_t op, ocsd_trc_index_t index_sop,
                                    const EtmV4ITrcPacket* pkt) override {
    for (auto& callback : callbacks_) {
      auto resp = callback->ProcessPacket(trace_id_, op, index_sop, pkt);
      if (IsRespError(resp)) {
        return resp;
      }
    }
    return OCSD_RESP_CONT;
  }

 private:
  uint8_t trace_id_;
  std::vector<PacketCallback*> callbacks_;
};

// For each trace_id, when given an addr, find the thread and map it belongs to.
class MapLocator : public PacketCallback {
 public:
  MapLocator(ThreadTree& thread_tree)
      : PacketCallback(PacketCallback::MAP_LOCATOR), thread_tree_(thread_tree) {}

  ThreadTree& GetThreadTree() { return thread_tree_; }

  // Return current thread id of a trace_id. If not available, return -1.
  pid_t GetTid(uint8_t trace_id) const { return trace_data_[trace_id].tid; }

  ocsd_datapath_resp_t ProcessPacket(uint8_t trace_id, ocsd_datapath_op_t op,
                                     ocsd_trc_index_t index_sop,
                                     const EtmV4ITrcPacket* pkt) override {
    TraceData& data = trace_data_[trace_id];
    if (op == OCSD_OP_DATA) {
      if (pkt != nullptr && ((!data.use_vmid && pkt->getContext().updated_c) ||
                             (data.use_vmid && pkt->getContext().updated_v))) {
        int32_t new_tid =
            static_cast<int32_t>(data.use_vmid ? pkt->getContext().VMID : pkt->getContext().ctxtID);
        if (data.tid != new_tid) {
          data.tid = new_tid;
          data.thread = nullptr;
          data.userspace_map = nullptr;
        }
      }
    } else if (op == OCSD_OP_RESET) {
      data.tid = -1;
      data.thread = nullptr;
      data.userspace_map = nullptr;
    }
    return OCSD_RESP_CONT;
  }

  const MapEntry* FindMap(uint8_t trace_id, uint64_t addr) {
    TraceData& data = trace_data_[trace_id];
    if (data.userspace_map != nullptr && data.userspace_map->Contains(addr)) {
      return data.userspace_map;
    }
    if (data.tid == -1) {
      return nullptr;
    }
    if (data.thread == nullptr) {
      data.thread = thread_tree_.FindThread(data.tid);
      if (data.thread == nullptr) {
        return nullptr;
      }
    }
    data.userspace_map = data.thread->maps->FindMapByAddr(addr);
    if (data.userspace_map != nullptr) {
      return data.userspace_map;
    }
    // We don't cache kernel map. Because kernel map can start from 0 and overlap all userspace
    // maps.
    return thread_tree_.GetKernelMaps().FindMapByAddr(addr);
  }

  void SetUseVmid(uint8_t trace_id, bool value) { trace_data_[trace_id].use_vmid = value; }

 private:
  struct TraceData {
    int32_t tid = -1;  // thread id, -1 if invalid
    const ThreadEntry* thread = nullptr;
    const MapEntry* userspace_map = nullptr;
    bool use_vmid = false;  // use vmid for PID
  };

  ThreadTree& thread_tree_;
  TraceData trace_data_[256];
};

// Map (trace_id, ip address) to (binary_path, binary_offset), and read binary files.
class MemAccess : public ITargetMemAccess {
 public:
  MemAccess(MapLocator& map_locator) : map_locator_(map_locator) {}

  ocsd_err_t ReadTargetMemory(const ocsd_vaddr_t address, uint8_t trace_id, ocsd_mem_space_acc_t,
                              uint32_t* num_bytes, uint8_t* p_buffer) override {
    TraceData& data = trace_data_[trace_id];
    const MapEntry* map = map_locator_.FindMap(trace_id, address);
    // fast path
    if (map != nullptr && map == data.buffer_map && address >= data.buffer_start &&
        address + *num_bytes <= data.buffer_end) {
      if (data.buffer == nullptr) {
        *num_bytes = 0;
      } else {
        memcpy(p_buffer, data.buffer + (address - data.buffer_start), *num_bytes);
      }
      return OCSD_OK;
    }

    // slow path
    size_t copy_size = 0;
    if (map != nullptr) {
      llvm::MemoryBuffer* memory = GetMemoryBuffer(map->dso);
      if (memory != nullptr) {
        if (auto opt_offset = map->dso->IpToFileOffset(address, map->start_addr, map->pgoff);
            opt_offset) {
          uint64_t offset = opt_offset.value();
          size_t file_size = memory->getBufferSize();
          copy_size = file_size > offset ? std::min<size_t>(file_size - offset, *num_bytes) : 0;
          if (copy_size > 0) {
            memcpy(p_buffer, memory->getBufferStart() + offset, copy_size);
          }
        }
      }
      // Update the last buffer cache.
      // Don't cache for the kernel map. Because simpleperf doesn't record an accurate kernel end
      // addr.
      if (!map->in_kernel) {
        data.buffer_map = map;
        data.buffer = memory == nullptr ? nullptr : (memory->getBufferStart() + map->pgoff);
        data.buffer_start = map->start_addr;
        data.buffer_end = map->get_end_addr();
      }
    }
    *num_bytes = copy_size;
    return OCSD_OK;
  }

 private:
  llvm::MemoryBuffer* GetMemoryBuffer(Dso* dso) {
    auto it = elf_map_.find(dso);
    if (it == elf_map_.end()) {
      ElfStatus status;
      auto res = elf_map_.emplace(dso, ElfFile::Open(dso->GetDebugFilePath(), &status));
      it = res.first;
    }
    return it->second ? it->second->GetMemoryBuffer() : nullptr;
  }

  struct TraceData {
    const MapEntry* buffer_map = nullptr;
    const char* buffer = nullptr;
    uint64_t buffer_start = 0;
    uint64_t buffer_end = 0;
  };

  MapLocator& map_locator_;
  std::unordered_map<Dso*, std::unique_ptr<ElfFile>> elf_map_;
  TraceData trace_data_[256];
};

class InstructionDecoder : public TrcIDecode {
 public:
  ocsd_err_t DecodeInstruction(ocsd_instr_info* instr_info) {
    this->instr_info = instr_info;
    return TrcIDecode::DecodeInstruction(instr_info);
  }

  ocsd_instr_info* instr_info;
};

// Similar to ITrcGenElemIn, but add next instruction info, which is needed to get branch to addr
// for an InstructionRange element.
struct ElementCallback {
 public:
  virtual ~ElementCallback(){};
  virtual ocsd_datapath_resp_t ProcessElement(ocsd_trc_index_t index_sop, uint8_t trace_id,
                                              const OcsdTraceElement& elem,
                                              const ocsd_instr_info* next_instr) = 0;
};

// Decode packets into elements.
class PacketToElement : public PacketCallback, public ITrcGenElemIn {
 public:
  PacketToElement(MapLocator& map_locator,
                  const std::unordered_map<uint8_t, std::unique_ptr<EtmV4Config>>& configs,
                  DecodeErrorLogger& error_logger)
      : PacketCallback(PacketCallback::PACKET_TO_ELEMENT), mem_access_(map_locator) {
    for (auto& p : configs) {
      uint8_t trace_id = p.first;
      const EtmV4Config* config = p.second.get();
      element_decoders_.emplace(trace_id, trace_id);
      auto& decoder = element_decoders_[trace_id];
      decoder.setProtocolConfig(config);
      decoder.getErrorLogAttachPt()->replace_first(&error_logger);
      decoder.getInstrDecodeAttachPt()->replace_first(&instruction_decoder_);
      decoder.getMemoryAccessAttachPt()->replace_first(&mem_access_);
      decoder.getTraceElemOutAttachPt()->replace_first(this);
    }
  }

  void AddCallback(ElementCallback* callback) { callbacks_.push_back(callback); }

  ocsd_datapath_resp_t ProcessPacket(uint8_t trace_id, ocsd_datapath_op_t op,
                                     ocsd_trc_index_t index_sop,
                                     const EtmV4ITrcPacket* pkt) override {
    return element_decoders_[trace_id].PacketDataIn(op, index_sop, pkt);
  }

  ocsd_datapath_resp_t TraceElemIn(const ocsd_trc_index_t index_sop, uint8_t trc_chan_id,
                                   const OcsdTraceElement& elem) override {
    for (auto& callback : callbacks_) {
      auto resp =
          callback->ProcessElement(index_sop, trc_chan_id, elem, instruction_decoder_.instr_info);
      if (IsRespError(resp)) {
        return resp;
      }
    }
    return OCSD_RESP_CONT;
  }

 private:
  // map from trace id of an etm device to its element decoder
  std::unordered_map<uint8_t, TrcPktDecodeEtmV4I> element_decoders_;
  MemAccess mem_access_;
  InstructionDecoder instruction_decoder_;
  std::vector<ElementCallback*> callbacks_;
};

// Dump etm data generated at different stages.
class DataDumper : public ElementCallback {
 public:
  DataDumper(ETMV4IDecodeTree& decode_tree) : decode_tree_(decode_tree) {}

  void DumpRawData() {
    decode_tree_.AttachRawFramePrinter(frame_printer_);
    frame_printer_.setMessageLogger(&stdout_logger_);
  }

  void DumpPackets(const std::unordered_map<uint8_t, std::unique_ptr<EtmV4Config>>& configs) {
    for (auto& p : configs) {
      uint8_t trace_id = p.first;
      auto result = packet_printers_.emplace(trace_id, trace_id);
      CHECK(result.second);
      auto& packet_printer = result.first->second;
      decode_tree_.AttachPacketMonitor(trace_id, packet_printer);
      packet_printer.setMessageLogger(&stdout_logger_);
    }
  }

  void DumpElements() { element_printer_.setMessageLogger(&stdout_logger_); }

  ocsd_datapath_resp_t ProcessElement(ocsd_trc_index_t index_sop, uint8_t trc_chan_id,
                                      const OcsdTraceElement& elem, const ocsd_instr_info*) {
    return element_printer_.TraceElemIn(index_sop, trc_chan_id, elem);
  }

 private:
  ETMV4IDecodeTree& decode_tree_;
  RawFramePrinter frame_printer_;
  std::unordered_map<uint8_t, PacketPrinter<EtmV4ITrcPacket>> packet_printers_;
  TrcGenericElementPrinter element_printer_;
  ocsdMsgLogger stdout_logger_;
};

// It decodes each ETMV4IPacket into TraceElements, and generates ETMInstrRanges from TraceElements.
// Decoding each packet is slow, but ensures correctness.
class InstrRangeParser : public ElementCallback {
 private:
  struct TraceData {
    ETMInstrRange instr_range;
    bool wait_for_branch_to_addr_fix = false;
  };

 public:
  InstrRangeParser(MapLocator& map_locator, const ETMDecoder::InstrRangeCallbackFn& callback)
      : map_locator_(map_locator), callback_(callback) {}

  ocsd_datapath_resp_t ProcessElement(const ocsd_trc_index_t, uint8_t trace_id,
                                      const OcsdTraceElement& elem,
                                      const ocsd_instr_info* next_instr) override {
    if (elem.getType() == OCSD_GEN_TRC_ELEM_INSTR_RANGE) {
      TraceData& data = trace_data_[trace_id];
      const MapEntry* map = map_locator_.FindMap(trace_id, elem.st_addr);
      if (map == nullptr) {
        FlushData(data);
        return OCSD_RESP_CONT;
      }
      uint64_t start_addr = map->GetVaddrInFile(elem.st_addr);
      auto& instr_range = data.instr_range;

      if (data.wait_for_branch_to_addr_fix) {
        // OpenCSD may cache a list of InstrRange elements, making it inaccurate to get branch to
        // address from next_instr->branch_addr. So fix it by using the start address of the next
        // InstrRange element.
        instr_range.branch_to_addr = start_addr;
      }
      FlushData(data);
      instr_range.dso = map->dso;
      instr_range.start_addr = start_addr;
      instr_range.end_addr = map->GetVaddrInFile(elem.en_addr - elem.last_instr_sz);
      bool end_with_branch =
          elem.last_i_type == OCSD_INSTR_BR || elem.last_i_type == OCSD_INSTR_BR_INDIRECT;
      bool branch_taken = end_with_branch && elem.last_instr_exec;
      if (elem.last_i_type == OCSD_INSTR_BR && branch_taken) {
        // It is based on the assumption that we only do immediate branch inside a binary,
        // which may not be true for all cases. TODO: http://b/151665001.
        instr_range.branch_to_addr = map->GetVaddrInFile(next_instr->branch_addr);
        data.wait_for_branch_to_addr_fix = true;
      } else {
        instr_range.branch_to_addr = 0;
      }
      instr_range.branch_taken_count = branch_taken ? 1 : 0;
      instr_range.branch_not_taken_count = branch_taken ? 0 : 1;

    } else if (elem.getType() == OCSD_GEN_TRC_ELEM_TRACE_ON) {
      // According to the ETM Specification, the Trace On element indicates a discontinuity in the
      // instruction trace stream. So it cuts the connection between instr ranges.
      FlushData(trace_data_[trace_id]);
    }
    return OCSD_RESP_CONT;
  }

  void FinishData() {
    for (auto& pair : trace_data_) {
      FlushData(pair.second);
    }
  }

 private:
  void FlushData(TraceData& data) {
    if (data.instr_range.dso != nullptr) {
      callback_(data.instr_range);
      data.instr_range.dso = nullptr;
    }
    data.wait_for_branch_to_addr_fix = false;
  }

  MapLocator& map_locator_;
  std::unordered_map<uint8_t, TraceData> trace_data_;
  ETMDecoder::InstrRangeCallbackFn callback_;
};

// It parses ETMBranchLists from ETMV4IPackets.
// It doesn't do element decoding and instruction decoding, thus is about 5 timers faster than
// InstrRangeParser. But some data will be lost when converting ETMBranchLists to InstrRanges:
//   1. InstrRanges described by Except packets (the last instructions executed before exeception,
//      about 2%?).
//   2. Branch to addresses of direct branch instructions across binaries.
class BranchListParser : public PacketCallback {
 private:
  struct TraceData {
    uint64_t addr = 0;
    uint8_t addr_valid_bits = 0;
    uint8_t isa = 0;
    bool invalid_branch = false;
    ETMBranchList branch;
  };

 public:
  BranchListParser(MapLocator& map_locator, const ETMDecoder::BranchListCallbackFn& callback)
      : PacketCallback(BRANCH_LIST_PARSER), map_locator_(map_locator), callback_(callback) {}

  void CheckConfigs(std::unordered_map<uint8_t, std::unique_ptr<EtmV4Config>>& configs) {
    // TODO: Current implementation doesn't support non-zero speculation length and return stack.
    for (auto& p : configs) {
      if (p.second->MaxSpecDepth() > 0) {
        LOG(WARNING) << "branch list collection isn't accurate with non-zero speculation length";
        break;
      }
    }
    for (auto& p : configs) {
      if (p.second->enabledRetStack()) {
        LOG(WARNING) << "branch list collection will lose some data with return stack enabled";
        break;
      }
    }
  }

  bool IsAddrPacket(const EtmV4ITrcPacket* pkt) {
    return pkt->getType() >= ETM4_PKT_I_ADDR_CTXT_L_32IS0 &&
           pkt->getType() <= ETM4_PKT_I_ADDR_L_64IS1;
  }

  bool IsAtomPacket(const EtmV4ITrcPacket* pkt) { return pkt->getAtom().num > 0; }

  ocsd_datapath_resp_t ProcessPacket(uint8_t trace_id, ocsd_datapath_op_t op,
                                     ocsd_trc_index_t /*index_sop */,
                                     const EtmV4ITrcPacket* pkt) override {
    TraceData& data = trace_data_[trace_id];
    if (op == OCSD_OP_DATA) {
      if (IsAddrPacket(pkt)) {
        // Flush branch when seeing an Addr packet. Because it isn't correct to concatenate
        // branches before and after an Addr packet.
        FlushBranch(data);
        data.addr = pkt->getAddrVal();
        data.addr_valid_bits = pkt->v_addr.valid_bits;
        data.isa = pkt->getAddrIS();
      }

      if (IsAtomPacket(pkt)) {
        // An atom packet contains a branch list. We may receive one or more atom packets in a row,
        // and need to concatenate them.
        ProcessAtomPacket(trace_id, data, pkt);
      }

    } else {
      // Flush branch when seeing a flush or reset operation.
      FlushBranch(data);
      if (op == OCSD_OP_RESET) {
        data.addr = 0;
        data.addr_valid_bits = 0;
        data.isa = 0;
        data.invalid_branch = false;
      }
    }
    return OCSD_RESP_CONT;
  }

  void FinishData() {
    for (auto& pair : trace_data_) {
      FlushBranch(pair.second);
    }
  }

 private:
  void ProcessAtomPacket(uint8_t trace_id, TraceData& data, const EtmV4ITrcPacket* pkt) {
    if (data.invalid_branch) {
      return;  // Skip atom packets when we think a branch list is invalid.
    }
    if (data.branch.branch.empty()) {
      // This is the first atom packet in a branch list. Check if we have tid and addr info to
      // parse it and the following atom packets. If not, mark the branch list as invalid.
      if (map_locator_.GetTid(trace_id) == -1 || data.addr_valid_bits == 0) {
        data.invalid_branch = true;
        return;
      }
      const MapEntry* map = map_locator_.FindMap(trace_id, data.addr);
      if (map == nullptr) {
        data.invalid_branch = true;
        return;
      }
      data.branch.dso = map->dso;
      data.branch.addr = map->GetVaddrInFile(data.addr);
      if (data.isa == 1) {  // thumb instruction, mark it in bit 0.
        data.branch.addr |= 1;
      }
    }
    uint32_t bits = pkt->atom.En_bits;
    for (size_t i = 0; i < pkt->atom.num; i++) {
      data.branch.branch.push_back((bits & 1) == 1);
      bits >>= 1;
    }
  }

  void FlushBranch(TraceData& data) {
    if (!data.branch.branch.empty()) {
      callback_(data.branch);
      data.branch.branch.clear();
    }
    data.invalid_branch = false;
  }

  MapLocator& map_locator_;
  ETMDecoder::BranchListCallbackFn callback_;
  std::unordered_map<uint8_t, TraceData> trace_data_;
};

// Etm data decoding in OpenCSD library has two steps:
// 1. From byte stream to etm packets. Each packet shows an event happened. For example,
// an Address packet shows the cpu is running the instruction at that address, an Atom
// packet shows whether the cpu decides to branch or not.
// 2. From etm packets to trace elements. To generates elements, the decoder needs both etm
// packets and executed binaries. For example, an InstructionRange element needs the decoder
// to find the next branch instruction starting from an address.
//
// ETMDecoderImpl uses OpenCSD library to decode etm data. It has the following properties:
// 1. Supports flexible decoding strategy. It allows installing packet callbacks and element
// callbacks, and decodes to either packets or elements based on requirements.
// 2. Supports dumping data at different stages.
class ETMDecoderImpl : public ETMDecoder {
 public:
  ETMDecoderImpl(ThreadTree& thread_tree) : thread_tree_(thread_tree) {}

  void CreateDecodeTree(const AuxTraceInfoRecord& auxtrace_info) {
    uint8_t trace_id = 0;
    uint64_t* info = auxtrace_info.data->info;
    for (int i = 0; i < auxtrace_info.data->nr_cpu; i++) {
      if (info[0] == AuxTraceInfoRecord::MAGIC_ETM4) {
        auto& etm4 = *reinterpret_cast<AuxTraceInfoRecord::ETM4Info*>(info);
        ocsd_etmv4_cfg cfg;
        memset(&cfg, 0, sizeof(cfg));
        cfg.reg_idr0 = etm4.trcidr0;
        cfg.reg_idr1 = etm4.trcidr1;
        cfg.reg_idr2 = etm4.trcidr2;
        cfg.reg_idr8 = etm4.trcidr8;
        cfg.reg_configr = etm4.trcconfigr;
        cfg.reg_traceidr = etm4.trctraceidr;
        cfg.arch_ver = ARCH_V8;
        cfg.core_prof = profile_CortexA;
        trace_id = cfg.reg_traceidr & 0x7f;
        trace_ids_.emplace(etm4.cpu, trace_id);
        configs_.emplace(trace_id, new EtmV4Config(&cfg));
        info = reinterpret_cast<uint64_t*>(&etm4 + 1);
      } else {
        CHECK_EQ(info[0], AuxTraceInfoRecord::MAGIC_ETE);
        auto& ete = *reinterpret_cast<AuxTraceInfoRecord::ETEInfo*>(info);
        ocsd_ete_cfg cfg;
        memset(&cfg, 0, sizeof(cfg));
        cfg.reg_idr0 = ete.trcidr0;
        cfg.reg_idr1 = ete.trcidr1;
        cfg.reg_idr2 = ete.trcidr2;
        cfg.reg_idr8 = ete.trcidr8;
        cfg.reg_devarch = ete.trcdevarch;
        cfg.reg_configr = ete.trcconfigr;
        cfg.reg_traceidr = ete.trctraceidr;
        cfg.arch_ver = ARCH_AA64;
        cfg.core_prof = profile_CortexA;
        trace_id = cfg.reg_traceidr & 0x7f;
        trace_ids_.emplace(ete.cpu, trace_id);
        configs_.emplace(trace_id, new ETEConfig(&cfg));
        info = reinterpret_cast<uint64_t*>(&ete + 1);
      }
      decode_tree_.CreateDecoder(configs_[trace_id].get());
      auto result = packet_sinks_.emplace(trace_id, trace_id);
      CHECK(result.second);
      decode_tree_.AttachPacketSink(trace_id, result.first->second);
    }
  }

  void EnableDump(const ETMDumpOption& option) override {
    dumper_.reset(new DataDumper(decode_tree_));
    if (option.dump_raw_data) {
      dumper_->DumpRawData();
    }
    if (option.dump_packets) {
      dumper_->DumpPackets(configs_);
    }
    if (option.dump_elements) {
      dumper_->DumpElements();
      InstallElementCallback(dumper_.get());
    }
  }

  void RegisterCallback(const InstrRangeCallbackFn& callback) {
    InstallMapLocator();
    instr_range_parser_.reset(new InstrRangeParser(*map_locator_, callback));
    InstallElementCallback(instr_range_parser_.get());
  }

  void RegisterCallback(const BranchListCallbackFn& callback) {
    InstallMapLocator();
    branch_list_parser_.reset(new BranchListParser(*map_locator_, callback));
    branch_list_parser_->CheckConfigs(configs_);
    InstallPacketCallback(branch_list_parser_.get());
  }

  bool ProcessData(const uint8_t* data, size_t size, bool formatted, uint32_t cpu) override {
    // Reset decoders before processing each data block. Because:
    // 1. Data blocks are not continuous. So decoders shouldn't keep previous states when
    //    processing a new block.
    // 2. The beginning part of a data block may be truncated if kernel buffer is temporarily full.
    //    So we may see garbage data, which can cause decoding errors if we don't reset decoders.
    LOG(DEBUG) << "Processing " << (!formatted ? "un" : "") << "formatted data with size " << size;
    auto& decoder = formatted ? decode_tree_.GetFormattedDataIn()
                              : decode_tree_.GetUnformattedDataIn(trace_ids_[cpu]);

    auto resp = decoder.TraceDataIn(OCSD_OP_RESET, data_index_, 0, nullptr, nullptr);
    if (IsRespError(resp)) {
      LOG(ERROR) << "failed to reset decoder, resp " << resp;
      return false;
    }
    size_t left_size = size;
    const size_t MAX_RESET_RETRY_COUNT = 3;
    size_t reset_retry_count = 0;
    while (left_size > 0) {
      uint32_t processed;
      auto resp = decoder.TraceDataIn(OCSD_OP_DATA, data_index_, left_size, data, &processed);
      if (IsRespError(resp)) {
        // A decoding error shouldn't ruin all data. Reset decoders to recover from it.
        // But some errors may not be recoverable by resetting decoders. So use a max retry limit.
        if (++reset_retry_count > MAX_RESET_RETRY_COUNT) {
          break;
        }
        LOG(DEBUG) << "reset etm decoders for seeing a decode failure, resp " << resp
                   << ", reset_retry_count is " << reset_retry_count;
        decoder.TraceDataIn(OCSD_OP_RESET, data_index_ + processed, 0, nullptr, nullptr);
      }
      data += processed;
      left_size -= processed;
      data_index_ += processed;
    }
    return true;
  }

  bool FinishData() override {
    if (instr_range_parser_) {
      instr_range_parser_->FinishData();
    }
    if (branch_list_parser_) {
      branch_list_parser_->FinishData();
    }
    return true;
  }

 private:
  void InstallMapLocator() {
    if (!map_locator_) {
      map_locator_.reset(new MapLocator(thread_tree_));
      for (auto& cfg : configs_) {
        int64_t configr = (*(const ocsd_etmv4_cfg*)*cfg.second).reg_configr;
        map_locator_->SetUseVmid(cfg.first,
                                 configr & (1U << ETM4_CFG_BIT_VMID | 1U << ETM4_CFG_BIT_VMID_OPT));
      }

      InstallPacketCallback(map_locator_.get());
    }
  }

  void InstallPacketCallback(PacketCallback* callback) {
    for (auto& p : packet_sinks_) {
      p.second.AddCallback(callback);
    }
  }

  void InstallElementCallback(ElementCallback* callback) {
    if (!packet_to_element_) {
      InstallMapLocator();
      packet_to_element_.reset(
          new PacketToElement(*map_locator_, configs_, decode_tree_.ErrorLogger()));
      InstallPacketCallback(packet_to_element_.get());
    }
    packet_to_element_->AddCallback(callback);
  }

  // map ip address to binary path and binary offset
  ThreadTree& thread_tree_;
  // handle to build OpenCSD decoder
  ETMV4IDecodeTree decode_tree_;
  // map from cpu to trace id
  std::unordered_map<uint64_t, uint8_t> trace_ids_;
  // map from the trace id of an etm device to its config
  std::unordered_map<uint8_t, std::unique_ptr<EtmV4Config>> configs_;
  // map from the trace id of an etm device to its PacketSink
  std::unordered_map<uint8_t, PacketSink> packet_sinks_;
  std::unique_ptr<PacketToElement> packet_to_element_;
  std::unique_ptr<DataDumper> dumper_;
  // an index keeping processed etm data size
  size_t data_index_ = 0;
  std::unique_ptr<InstrRangeParser> instr_range_parser_;
  std::unique_ptr<MapLocator> map_locator_;
  std::unique_ptr<BranchListParser> branch_list_parser_;
};

}  // namespace

bool ParseEtmDumpOption(const std::string& s, ETMDumpOption* option) {
  for (auto& value : android::base::Split(s, ",")) {
    if (value == "raw") {
      option->dump_raw_data = true;
    } else if (value == "packet") {
      option->dump_packets = true;
    } else if (value == "element") {
      option->dump_elements = true;
    } else {
      LOG(ERROR) << "unknown etm dump option: " << value;
      return false;
    }
  }
  return true;
}

std::unique_ptr<ETMDecoder> ETMDecoder::Create(const AuxTraceInfoRecord& auxtrace_info,
                                               ThreadTree& thread_tree) {
  auto decoder = std::make_unique<ETMDecoderImpl>(thread_tree);
  decoder->CreateDecodeTree(auxtrace_info);
  return std::unique_ptr<ETMDecoder>(decoder.release());
}

// Use OpenCSD instruction decoder to convert branches to instruction addresses.
class BranchDecoder {
 public:
  android::base::expected<void, std::string> Init(Dso* dso) {
    ElfStatus status;
    elf_ = ElfFile::Open(dso->GetDebugFilePath(), &status);
    if (!elf_) {
      std::stringstream ss;
      ss << status;
      return android::base::unexpected(ss.str());
    }
    if (dso->type() == DSO_KERNEL_MODULE) {
      // Kernel module doesn't have program header. So create a fake one mapping to .text section.
      for (const auto& section : elf_->GetSectionHeader()) {
        if (section.name == ".text") {
          segments_.resize(1);
          segments_[0].is_executable = true;
          segments_[0].is_load = true;
          segments_[0].file_offset = section.file_offset;
          segments_[0].file_size = section.size;
          segments_[0].vaddr = section.vaddr;
          break;
        }
      }
    } else {
      segments_ = elf_->GetProgramHeader();
      auto it = std::remove_if(segments_.begin(), segments_.end(),
                               [](const ElfSegment& s) { return !s.is_executable; });
      segments_.resize(it - segments_.begin());
    }
    if (segments_.empty()) {
      return android::base::unexpected("no segments");
    }
    buffer_ = elf_->GetMemoryBuffer();
    return {};
  }

  void SetAddr(uint64_t addr, bool is_thumb) {
    memset(&instr_info_, 0, sizeof(instr_info_));
    instr_info_.pe_type.arch = ARCH_V8;
    instr_info_.pe_type.profile = profile_CortexA;
    instr_info_.isa =
        elf_->Is64Bit() ? ocsd_isa_aarch64 : (is_thumb ? ocsd_isa_thumb2 : ocsd_isa_arm);
    instr_info_.instr_addr = addr;
  }

  bool FindNextBranch() {
    // Loop until we find a branch instruction.
    while (ReadMem(instr_info_.instr_addr, 4, &instr_info_.opcode)) {
      ocsd_err_t err = instruction_decoder_.DecodeInstruction(&instr_info_);
      if (err != OCSD_OK) {
        break;
      }
      if (instr_info_.type != OCSD_INSTR_OTHER) {
        return true;
      }
      instr_info_.instr_addr += instr_info_.instr_size;
    }
    return false;
  };

  ocsd_instr_info& InstrInfo() { return instr_info_; }

 private:
  bool ReadMem(uint64_t vaddr, size_t size, void* data) {
    for (auto& segment : segments_) {
      if (vaddr >= segment.vaddr && vaddr + size <= segment.vaddr + segment.file_size) {
        uint64_t offset = vaddr - segment.vaddr + segment.file_offset;
        memcpy(data, buffer_->getBufferStart() + offset, size);
        return true;
      }
    }
    return false;
  }

  std::unique_ptr<ElfFile> elf_;
  std::vector<ElfSegment> segments_;
  llvm::MemoryBuffer* buffer_ = nullptr;
  ocsd_instr_info instr_info_;
  InstructionDecoder instruction_decoder_;
};

android::base::expected<void, std::string> ConvertBranchMapToInstrRanges(
    Dso* dso, const BranchMap& branch_map, const ETMDecoder::InstrRangeCallbackFn& callback) {
  ETMInstrRange instr_range;
  instr_range.dso = dso;

  BranchDecoder decoder;
  if (auto result = decoder.Init(dso); !result.ok()) {
    return result;
  }

  for (const auto& addr_p : branch_map) {
    uint64_t start_addr = addr_p.first & ~1ULL;
    bool is_thumb = addr_p.first & 1;
    for (const auto& branch_p : addr_p.second) {
      const std::vector<bool>& branch = branch_p.first;
      uint64_t count = branch_p.second;
      decoder.SetAddr(start_addr, is_thumb);

      for (bool b : branch) {
        ocsd_instr_info& instr = decoder.InstrInfo();
        uint64_t from_addr = instr.instr_addr;
        if (!decoder.FindNextBranch()) {
          break;
        }
        bool end_with_branch = instr.type == OCSD_INSTR_BR || instr.type == OCSD_INSTR_BR_INDIRECT;
        bool branch_taken = end_with_branch && b;
        instr_range.start_addr = from_addr;
        instr_range.end_addr = instr.instr_addr;
        if (instr.type == OCSD_INSTR_BR) {
          instr_range.branch_to_addr = instr.branch_addr;
        } else {
          instr_range.branch_to_addr = 0;
        }
        instr_range.branch_taken_count = branch_taken ? count : 0;
        instr_range.branch_not_taken_count = branch_taken ? 0 : count;

        callback(instr_range);

        if (b) {
          instr.instr_addr = instr.branch_addr;
        } else {
          instr.instr_addr += instr.instr_size;
        }
      }
    }
  }
  return {};
}

}  // namespace simpleperf