compiler/debug/elf_gnu_debugdata_writer.h

/*
 * 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.
 */

#ifndef ART_COMPILER_DEBUG_ELF_GNU_DEBUGDATA_WRITER_H_
#define ART_COMPILER_DEBUG_ELF_GNU_DEBUGDATA_WRITER_H_

#include <vector>

#include "arch/instruction_set.h"
#include "linker/elf_builder.h"
#include "linker/vector_output_stream.h"

// liblzma.
#include "7zCrc.h"
#include "XzCrc64.h"
#include "XzEnc.h"

namespace art {
namespace debug {

static void XzCompress(const std::vector<uint8_t>* src, std::vector<uint8_t>* dst) {
  // Configure the compression library.
  CrcGenerateTable();
  Crc64GenerateTable();
  CLzma2EncProps lzma2Props;
  Lzma2EncProps_Init(&lzma2Props);
  lzma2Props.lzmaProps.level = 1;  // Fast compression.
  Lzma2EncProps_Normalize(&lzma2Props);
  CXzProps props;
  XzProps_Init(&props);
  props.lzma2Props = lzma2Props;
  // Implement the required interface for communication (written in C so no virtual methods).
  struct XzCallbacks : public ISeqInStream, public ISeqOutStream, public ICompressProgress {
    static SRes ReadImpl(const ISeqInStream* p, void* buf, size_t* size) {
      auto* ctx = static_cast<XzCallbacks*>(const_cast<ISeqInStream*>(p));
      *size = std::min(*size, ctx->src_->size() - ctx->src_pos_);
      memcpy(buf, ctx->src_->data() + ctx->src_pos_, *size);
      ctx->src_pos_ += *size;
      return SZ_OK;
    }
    static size_t WriteImpl(const ISeqOutStream* p, const void* buf, size_t size) {
      auto* ctx = static_cast<const XzCallbacks*>(p);
      const uint8_t* buffer = reinterpret_cast<const uint8_t*>(buf);
      ctx->dst_->insert(ctx->dst_->end(), buffer, buffer + size);
      return size;
    }
    static SRes ProgressImpl(const ICompressProgress* , UInt64, UInt64) {
      return SZ_OK;
    }
    size_t src_pos_;
    const std::vector<uint8_t>* src_;
    std::vector<uint8_t>* dst_;
  };
  XzCallbacks callbacks;
  callbacks.Read = XzCallbacks::ReadImpl;
  callbacks.Write = XzCallbacks::WriteImpl;
  callbacks.Progress = XzCallbacks::ProgressImpl;
  callbacks.src_pos_ = 0;
  callbacks.src_ = src;
  callbacks.dst_ = dst;
  // Compress.
  SRes res = Xz_Encode(&callbacks, &callbacks, &props, &callbacks);
  CHECK_EQ(res, SZ_OK);
}

template <typename ElfTypes>
static std::vector<uint8_t> MakeMiniDebugInfoInternal(
    InstructionSet isa,
    const InstructionSetFeatures* features,
    typename ElfTypes::Addr text_section_address,
    size_t text_section_size,
    typename ElfTypes::Addr dex_section_address,
    size_t dex_section_size,
    const DebugInfo& debug_info) {
  std::vector<uint8_t> buffer;
  buffer.reserve(KB);
  linker::VectorOutputStream out("Mini-debug-info ELF file", &buffer);
  std::unique_ptr<linker::ElfBuilder<ElfTypes>> builder(
      new linker::ElfBuilder<ElfTypes>(isa, features, &out));
  builder->Start(false /* write_program_headers */);
  // Mirror ELF sections as NOBITS since the added symbols will reference them.
  builder->GetText()->AllocateVirtualMemory(text_section_address, text_section_size);
  if (dex_section_size != 0) {
    builder->GetDex()->AllocateVirtualMemory(dex_section_address, dex_section_size);
  }
  WriteDebugSymbols(builder.get(), true /* mini-debug-info */, debug_info);
  WriteCFISection(builder.get(),
                  debug_info.compiled_methods,
                  dwarf::DW_DEBUG_FRAME_FORMAT,
                  false /* write_oat_paches */);
  builder->End();
  CHECK(builder->Good());
  std::vector<uint8_t> compressed_buffer;
  compressed_buffer.reserve(buffer.size() / 4);
  XzCompress(&buffer, &compressed_buffer);
  return compressed_buffer;
}

}  // namespace debug
}  // namespace art

#endif  // ART_COMPILER_DEBUG_ELF_GNU_DEBUGDATA_WRITER_H_