Remove more things

runtime/vm/elfgen.h

-// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
-// for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
-
-#ifndef VM_ELFGEN_H_
-#define VM_ELFGEN_H_
-
-#include "vm/lockers.h"
-#include "vm/os_thread.h"
-
-namespace dart {
-
-// -----------------------------------------------------------------------------
-// Implementation of ElfGen
-//
-// Specification documents:
-//   http://refspecs.freestandards.org
-//
-//   ELF generic ABI:
-//     http://refspecs.freestandards.org/elf/gabi4+/contents.html
-//   ELF processor-specific supplement for X86_64:
-//     http://refspecs.freestandards.org/elf/x86_64-SysV-psABI.pdf
-//   DWARF 2.0:
-//     http://refspecs.freestandards.org/dwarf/dwarf-2.0.0.pdf
-
-// Forward declarations.
-class File;
-
-// ElfGen is used to generate minimal ELF information containing code, symbols,
-// and line numbers for generated code in the dart VM. This information is
-// used in two ways:
-// - it is used to generate in-memory ELF information which is then
-//   registered with gdb using the JIT interface.
-// - it is also used to generate a file with the ELF information. This file
-//   is not executed, but read by pprof to analyze Dart programs.
-
-class ElfGen {
- public:
-  ElfGen();
-  ~ElfGen();
-
-  // Add the code starting at pc.
-  void AddCode(uword pc, intptr_t size);
-
-  // Add symbol information for a region (includes the start and end symbol),
-  // does not add the actual code.
-  void AddCodeRegion(const char* name, uword pc, intptr_t size);
-
-  // Add specified symbol information, does not add the actual code.
-  int AddFunction(const char* name, uword pc, intptr_t size);
-
-  // Write out all the Elf information using the specified handle.
-  bool WriteToFile(File* handle);
-  bool WriteToMemory(DebugInfo::ByteBuffer* region);
-
-  // Register this generated section with GDB using the JIT interface.
-  static void RegisterSectionWithGDB(const char* name,
-                                     uword entry_point,
-                                     intptr_t size);
-
-  // Unregister all generated section from GDB.
-  static void UnregisterAllSectionsWithGDB();
-
- private:
-  // ELF helpers
-  typedef int (*OutputWriter)(void* handle,
-                              const DebugInfo::ByteBuffer& section);
-  typedef void (*OutputPadder)(void* handle, int padding_size);
-
-  int AddString(DebugInfo::ByteBuffer* buf, const char* str);
-  int AddSectionName(const char* str);
-  int AddName(const char* str);
-  void AddELFHeader(int shoff);
-  void AddSectionHeader(int section, int offset);
-  int PadSection(DebugInfo::ByteBuffer* section, int offset, int alignment);
-  bool WriteOutput(void* handle, OutputWriter writer, OutputPadder padder);
-
-  uword text_vma_;  // text section vma
-  intptr_t text_size_;  // text section size
-  int text_padding_;  // padding preceding text section
-
-  static const int kNumSections = 5;  // we generate 5 sections
-  int section_name_[kNumSections];  // array of section name indices
-  DebugInfo::ByteBuffer section_buf_[kNumSections];  // array of section buffers
-  DebugInfo::ByteBuffer header_;  // ELF header buffer
-  DebugInfo::ByteBuffer sheaders_;  // section header table buffer
-  DebugInfo::ByteBuffer lineprog_;  // line statement program, part of
-                                    // '.debug_line' section
-
-  // current state of the DWARF line info generator
-  uintptr_t cur_addr_;  // current pc
-  int map_offset_;
-  uword map_begin_;
-  uword map_end_;
-
-  Mutex lock_;
-};
-
-
-enum {
-  // Various constant sizes for ELF files.
-  kAddrSize = sizeof(uword),
-  kPageSize = 4*1024,  // Memory mapping page size.
-  kTextAlign = 16,
-  kELFHeaderSize = 40 + 3*kAddrSize,
-  kProgramHeaderEntrySize = 8 + 6*kAddrSize,
-  kSectionHeaderEntrySize = 16 + 6*kAddrSize,
-  kSymbolSize = 8 + 2*kAddrSize,
-
-  // Our own layout of sections.
-  kUndef = 0,   // Undefined section.
-  kText,        // Text section.
-  kShStrtab,    // Section header string table.
-  kStrtab,      // String table.
-  kSymtab,      // Symbol table.
-  kNumSections,  // Num of section header entries in section header table.
-
-  // Various ELF constants.
-  kELFCLASS32 = 1,
-  kELFCLASS64 = 2,
-  kELFDATA2LSB = 1,
-  kELFDATA2MSB = 2,
-  kEM_386 = 3,
-  kEM_MIPS = 8,
-  kEM_ARM = 40,
-  kEM_X86_64 = 62,
-  kEV_CURRENT = 1,
-  kET_EXEC = 2,  // not used
-  kET_DYN = 3,
-  kSHT_PROGBITS = 1,
-  kSHT_SYMTAB = 2,
-  kSHT_STRTAB = 3,
-  kSHF_WRITE = 1,  // not used
-  kSHF_ALLOC = 2,
-  kSHF_EXECINSTR = 4,
-  kSTB_LOCAL = 0,
-  kSTB_EXPORTED = 1,
-  kSTT_FUNC = 2,
-};
-
-
-// ELF and DWARF constants.
-static const char* kEI_MAG0_MAG3 = "\177ELF";
-static const uint8_t kSpecialOpcodeLengths[] = { 0, 1, 1, 1, 1, 0, 0, 0, 1 };
-
-
-// Section attributes.
-// The field names correspond to the field names of Elf32_Shdr and Elf64_Shdr.
-static const struct {
-  // Section header index (only used to check correct section order).
-  int shndx;
-  const char* name;  // sh_name will be the index of name inserted in shstrtab.
-  int sh_type;
-  int sh_flags;
-  int sh_link;
-  int sh_addralign;
-  int sh_entsize;
-} section_attr[kNumSections + 1] = {
-  { kUndef,      "",               0,             0,
-    0,       0,           0           },
-  { kText,       ".text",          kSHT_PROGBITS, kSHF_ALLOC|kSHF_EXECINSTR,
-    0,       kTextAlign,  0           },
-  { kShStrtab,   ".shstrtab",      kSHT_STRTAB,   0,
-    0,       1,           0           },
-  { kStrtab,     ".strtab",        kSHT_STRTAB,   0,
-    0,       1,           0           },
-  { kSymtab,     ".symtab",        kSHT_SYMTAB,   0,
-    kStrtab, kAddrSize,   kSymbolSize },
-  // Sentinel to pad the last section
-  // for proper alignment of section header table.
-  { 0,          "",               0,             0,
-    0,       kAddrSize,   0           }
-};
-
-
-// Convenience function aligning an integer.
-static inline uintptr_t Align(uintptr_t x, intptr_t size) {
-  // size is a power of 2
-  ASSERT((size & (size-1)) == 0);
-  return (x + (size-1)) & ~(size-1);
-}
-
-
-// Convenience function writing a single byte to a ByteBuffer.
-static inline void WriteByte(DebugInfo::ByteBuffer* buf, uint8_t byte) {
-  buf->Add(byte);
-}
-
-
-// Convenience function writing an unsigned native word to a ByteBuffer.
-// The word is 32-bit wide in 32-bit mode and 64-bit wide in 64-bit mode.
-static inline void WriteWord(DebugInfo::ByteBuffer* buf, uword word) {
-  uint8_t* p = reinterpret_cast<uint8_t*>(&word);
-  for (size_t i = 0; i < sizeof(word); i++) {
-    buf->Add(p[i]);
-  }
-}
-
-static inline void WriteInt(DebugInfo::ByteBuffer* buf, int word) {
-  uint8_t* p = reinterpret_cast<uint8_t*>(&word);
-  for (size_t i = 0; i < sizeof(word); i++) {
-    buf->Add(p[i]);
-  }
-}
-
-static inline void WriteShort(DebugInfo::ByteBuffer* buf, uint16_t word) {
-  uint8_t* p = reinterpret_cast<uint8_t*>(&word);
-  for (size_t i = 0; i < sizeof(word); i++) {
-    buf->Add(p[i]);
-  }
-}
-
-static inline void WriteString(DebugInfo::ByteBuffer* buf, const char* str) {
-  for (size_t i = 0; i < strlen(str); i++) {
-    buf->Add(static_cast<uint8_t>(str[i]));
-  }
-}
-
-static inline void Write(DebugInfo::ByteBuffer* buf,
-                         const void* mem,
-                         int length) {
-  const uint8_t* p = reinterpret_cast<const uint8_t*>(mem);
-  for (int i = 0; i < length; i++) {
-    buf->Add(p[i]);
-  }
-}
-
-
-// Write given section to file and return written size.
-static int WriteSectionToFile(void* handle,
-                              const DebugInfo::ByteBuffer& section) {
-#if 0
-  File* fp = reinterpret_cast<File*>(handle);
-  int size = section.size();
-  fp->WriteFully(section.data(), size);
-  return size;
-#else
-  return 0;
-#endif
-}
-
-
-// Pad output file to specified padding size.
-static void PadFile(void* handle, int padding_size) {
-#if 0
-  File* fp = reinterpret_cast<File*>(handle);
-  for (int i = 0; i < padding_size; i++) {
-    fp->WriteFully("", 1);
-  }
-#endif
-}
-
-
-// Write given section to specified memory region and return written size.
-static int WriteSectionToMemory(void* handle,
-                                const DebugInfo::ByteBuffer& section) {
-  DebugInfo::ByteBuffer* buffer =
-      reinterpret_cast<DebugInfo::ByteBuffer*>(handle);
-  int size = section.size();
-  for (int i = 0; i < size; i++) {
-    buffer->Add(static_cast<uint8_t>(section.data()[i]));
-  }
-  return size;
-}
-
-
-// Pad memory to specified padding size.
-static void PadMemory(void* handle, int padding_size) {
-  DebugInfo::ByteBuffer* buffer =
-      reinterpret_cast<DebugInfo::ByteBuffer*>(handle);
-  for (int i = 0; i < padding_size; i++) {
-    buffer->Add(static_cast<uint8_t>(0));
-  }
-}
-
-
-// Constructor
-ElfGen::ElfGen()
-    : text_vma_(0), text_size_(0), text_padding_(0), map_offset_(0), lock_() {
-  for (int i = 0; i < kNumSections; i++) {
-    ASSERT(section_attr[i].shndx == i);  // Verify layout of sections.
-    section_name_[i] = AddSectionName(section_attr[i].name);
-  }
-  // Section header string table always starts with an empty string, which is
-  // the name of the kUndef section.
-  ASSERT((section_attr[0].name[0] == '\0') && (section_name_[0] == 0));
-
-  // String table always starts with an empty string.
-  AddName("");
-  ASSERT(section_buf_[kStrtab].size() == 1);
-
-  // Symbol at index 0 in symtab is always STN_UNDEF (all zero):
-  DebugInfo::ByteBuffer* symtab = &section_buf_[kSymtab];
-  while (symtab->size() < kSymbolSize) {
-    WriteInt(symtab, 0);
-  }
-  ASSERT(symtab->size() == kSymbolSize);
-}
-
-
-// Destructor
-ElfGen::~ElfGen() {
-}
-
-
-void ElfGen::AddCode(uword pc, intptr_t size) {
-  MutexLocker ml(&lock_);
-  text_vma_ = pc;
-  text_size_ = size;
-  // We pad the text section in the file to align absolute code addresses with
-  // corresponding file offsets as if the code had been loaded by memory
-  // mapping.
-  if (text_vma_ % kPageSize < kELFHeaderSize) {
-    text_padding_ = text_vma_ % kPageSize + kPageSize - kELFHeaderSize;
-  } else {
-    text_padding_ = text_vma_ % kPageSize - kELFHeaderSize;
-  }
-
-  Write(&section_buf_[kText], reinterpret_cast<void*>(pc), size);
-  // map_offset is the file offset of the first mapped page.
-  map_offset_ = (kELFHeaderSize + text_padding_)/kPageSize*kPageSize;
-  map_begin_ = Align(text_vma_ - kPageSize + 1, kPageSize);
-  map_end_ = Align(text_vma_ + size, kPageSize);
-}
-
-
-void ElfGen::AddCodeRegion(const char* name, uword pc, intptr_t size) {
-  MutexLocker ml(&lock_);
-  AddFunction(name, pc, size);
-  char end_name[256];
-  OS::SNPrint(end_name, sizeof(end_name), "%s_end", name);
-  AddFunction(end_name, pc + size, 0);
-}
-
-
-int ElfGen::AddFunction(const char* name, uword pc, intptr_t size) {
-  ASSERT(text_vma_ != 0);  // code must have been added
-  DebugInfo::ByteBuffer* symtab = &section_buf_[kSymtab];
-  const int beg = symtab->size();
-  WriteInt(symtab, AddName(name));  // st_name
-#if defined(ARCH_IS_64_BIT)
-  WriteShort(symtab, (kSTB_LOCAL << 4) + kSTT_FUNC);  // st_info + (st_other<<8)
-  WriteShort(symtab, kText);  // st_shndx
-#endif
-  WriteWord(symtab, pc);  // st_value
-  WriteWord(symtab, size);  // st_size
-#if defined(ARCH_IS_32_BIT)
-  // st_info + (st_other<<8)
-  WriteShort(symtab, (kSTB_EXPORTED << 4) + kSTT_FUNC);
-  WriteShort(symtab, kText);  // st_shndx
-#endif
-  ASSERT(symtab->size() - beg == kSymbolSize);
-  return beg / kSymbolSize;  // symbol index in symtab
-}
-
-
-bool ElfGen::WriteToFile(File* handle) {
-  return WriteOutput(handle, WriteSectionToFile, PadFile);
-}
-
-
-bool ElfGen::WriteToMemory(DebugInfo::ByteBuffer* region) {
-  return WriteOutput(region, WriteSectionToMemory, PadMemory);
-}
-
-
-int ElfGen::AddString(DebugInfo::ByteBuffer* buf, const char* str) {
-  const int str_index = buf->size();
-  WriteString(buf, str);
-  WriteByte(buf, 0);  // terminating '\0'
-  return str_index;
-}
-
-
-int ElfGen::AddSectionName(const char* str) {
-  return AddString(&section_buf_[kShStrtab], str);
-}
-
-
-int ElfGen::AddName(const char* str) {
-  return AddString(&section_buf_[kStrtab], str);
-}
-
-
-void ElfGen::AddELFHeader(int shoff) {
-  ASSERT(text_vma_ != 0);  // Code must have been added.
-  Write(&header_, kEI_MAG0_MAG3, 4);  // EI_MAG0..EI_MAG3
-#if defined(ARCH_IS_32_BIT)
-  WriteByte(&header_, kELFCLASS32);  // EI_CLASS
-#elif defined(ARCH_IS_64_BIT)
-  WriteByte(&header_, kELFCLASS64);  // EI_CLASS
-#else
-#error Unknown architecture.
-#endif
-  WriteByte(&header_, kELFDATA2LSB);  // EI_DATA
-  WriteByte(&header_, kEV_CURRENT);  // EI_VERSION
-  WriteByte(&header_, 0);  // EI_PAD
-  WriteInt(&header_, 0);  // EI_PAD
-  WriteInt(&header_, 0);  // EI_PAD
-  WriteShort(&header_, kET_DYN);  // e_type, fake a shared object.
-#if defined(TARGET_ARCH_IA32)
-  WriteShort(&header_, kEM_386);  // e_machine
-#elif defined(TARGET_ARCH_X64)
-  WriteShort(&header_, kEM_X86_64);  // e_machine
-#elif defined(TARGET_ARCH_ARM)
-  WriteShort(&header_, kEM_ARM);  // e_machine
-#elif defined(TARGET_ARCH_ARM64)
-  // TODO(zra): Find the right ARM64 constant.
-  WriteShort(&header_, kEM_ARM);  // e_machine
-#elif defined(TARGET_ARCH_MIPS)
-  WriteShort(&header_, kEM_MIPS);  // e_machine
-#else
-#error Unknown architecture.
-#endif
-  WriteInt(&header_, kEV_CURRENT);  // e_version
-  WriteWord(&header_, 0);  // e_entry: none
-  WriteWord(&header_, 0);  // e_phoff: no program header table.
-  WriteWord(&header_, shoff);  // e_shoff: section header table offset.
-  WriteInt(&header_, 0);  // e_flags: no flags.
-  WriteShort(&header_, kELFHeaderSize);  // e_ehsize: header size.
-  WriteShort(&header_, kProgramHeaderEntrySize);  // e_phentsize
-  WriteShort(&header_, 0);  // e_phnum: no entries program header table.
-  WriteShort(&header_, kSectionHeaderEntrySize);  // e_shentsize
-  // e_shnum: number of section header entries.
-  WriteShort(&header_, kNumSections);
-  WriteShort(&header_, kShStrtab);  // e_shstrndx: index of shstrtab.
-  ASSERT(header_.size() == kELFHeaderSize);
-}
-
-
-void ElfGen::AddSectionHeader(int section, int offset) {
-  WriteInt(&sheaders_, section_name_[section]);
-  WriteInt(&sheaders_, section_attr[section].sh_type);
-  WriteWord(&sheaders_, section_attr[section].sh_flags);
-  // sh_addr: abs addr
-  WriteWord(&sheaders_, (section == kText) ? text_vma_ : 0);
-  WriteWord(&sheaders_, offset);  // sh_offset: section file offset.
-  WriteWord(&sheaders_, section_buf_[section].size());
-  WriteInt(&sheaders_, section_attr[section].sh_link);
-  WriteInt(&sheaders_, 0);
-  WriteWord(&sheaders_, section_attr[section].sh_addralign);
-  WriteWord(&sheaders_, section_attr[section].sh_entsize);
-  ASSERT(sheaders_.size() == kSectionHeaderEntrySize * (section + 1));
-}
-
-
-// Pads the given section with zero bytes for the given aligment, assuming the
-// section starts at given file offset; returns file offset after padded
-// section.
-int ElfGen::PadSection(DebugInfo::ByteBuffer* section,
-                       int offset,
-                       int alignment) {
-  offset += section->size();
-  int aligned_offset = Align(offset, alignment);
-  while (offset++ < aligned_offset) {
-    WriteByte(section, 0);  // one byte padding.
-  }
-  return aligned_offset;
-}
-
-
-bool ElfGen::WriteOutput(void* handle,
-                         OutputWriter writer,
-                         OutputPadder padder) {
-  if (handle == NULL || writer == NULL || padder == NULL) {
-    return false;
-  }
-
-  // Align all sections before writing the ELF header in order to calculate the
-  // file offset of the section header table, which is needed in the ELF header.
-  // Pad each section as required by the aligment constraint of the immediately
-  // following section, except the ELF header section, which requires special
-  // padding (text_padding_) to align the text_ section.
-  int offset = kELFHeaderSize + text_padding_;
-  for (int i = kText; i < kNumSections; i++) {
-    offset = PadSection(&section_buf_[i],
-                        offset,
-                        section_attr[i+1].sh_addralign);
-  }
-
-  const int shoff = offset;  // Section header table offset.
-
-  // Write elf header.
-  AddELFHeader(shoff);
-  offset = (*writer)(handle, header_);
-
-  // Pad file before writing text section in order to align vma with file
-  // offset.
-  (*padder)(handle, text_padding_);
-
-  offset += text_padding_;
-  ASSERT((text_vma_ - offset) % kPageSize == 0);
-
-  // Section header at index 0 in section header table is always SHN_UNDEF:
-  for (int i = 0; i < kNumSections; i++) {
-    AddSectionHeader(i, offset);
-    offset += (*writer)(handle, section_buf_[i]);
-  }
-  // Write section header table.
-  ASSERT(offset == shoff);
-  offset += (*writer)(handle, sheaders_);
-  ASSERT(offset == shoff + kNumSections * kSectionHeaderEntrySize);
-
-  return true;
-}
-
-}  // namespace dart
-
-#endif  // VM_ELFGEN_H_