courgette/encoded_program.h

   1 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef COURGETTE_ENCODED_PROGRAM_H_
   6 #define COURGETTE_ENCODED_PROGRAM_H_
   7
   8 #include <vector>
   9
  10 #include "base/basictypes.h"
  11 #include "courgette/disassembler.h"
  12 #include "courgette/memory_allocator.h"
  13 #include "courgette/types_elf.h"
  14
  15 namespace courgette {
  16
  17 class SinkStream;
  18 class SinkStreamSet;
  19 class SourceStreamSet;
  20
  21 // An EncodedProgram is a set of tables that contain a simple 'binary assembly
  22 // language' that can be assembled to produce a sequence of bytes, for example,
  23 // a Windows 32-bit executable.
  24 //
  25 class EncodedProgram {
  26  public:
  27   EncodedProgram();
  28   ~EncodedProgram();
  29
  30   // Generating an EncodedProgram:
  31   //
  32   // (1) The image base can be specified at any time.
  33   void set_image_base(uint64 base) { image_base_ = base; }
  34
  35   // (2) Address tables and indexes defined first.
  36   CheckBool DefineRel32Label(int index, RVA address) WARN_UNUSED_RESULT;
  37   CheckBool DefineAbs32Label(int index, RVA address) WARN_UNUSED_RESULT;
  38   void EndLabels();
  39
  40   // (3) Add instructions in the order needed to generate bytes of file.
  41   // NOTE: If any of these methods ever fail, the EncodedProgram instance
  42   // has failed and should be discarded.
  43   CheckBool AddOrigin(RVA rva) WARN_UNUSED_RESULT;
  44   CheckBool AddCopy(uint32 count, const void* bytes) WARN_UNUSED_RESULT;
  45   CheckBool AddRel32(int label_index) WARN_UNUSED_RESULT;
  46   CheckBool AddRel32ARM(uint16 op, int label_index) WARN_UNUSED_RESULT;
  47   CheckBool AddAbs32(int label_index) WARN_UNUSED_RESULT;
  48   CheckBool AddPeMakeRelocs() WARN_UNUSED_RESULT;
  49   CheckBool AddElfMakeRelocs() WARN_UNUSED_RESULT;
  50   CheckBool AddElfARMMakeRelocs() WARN_UNUSED_RESULT;
  51
  52   // (3) Serialize binary assembly language tables to a set of streams.
  53   CheckBool WriteTo(SinkStreamSet* streams) WARN_UNUSED_RESULT;
  54
  55   // Using an EncodedProgram to generate a byte stream:
  56   //
  57   // (4) Deserializes a fresh EncodedProgram from a set of streams.
  58   bool ReadFrom(SourceStreamSet* streams);
  59
  60   // (5) Assembles the 'binary assembly language' into final file.
  61   CheckBool AssembleTo(SinkStream* buffer) WARN_UNUSED_RESULT;
  62
  63  private:
  64   // Binary assembly language operations.
  65   // These are part of the patch format. Reusing an existing value will
  66   // break backwards compatibility.
  67   enum OP {
  68     ORIGIN = 0,    // ORIGIN <rva> - set address for subsequent assembly.
  69     COPY = 1,      // COPY <count> <bytes> - copy bytes to output.
  70     COPY1 = 2,     // COPY1 <byte> - same as COPY 1 <byte>.
  71     REL32 = 3,     // REL32 <index> - emit rel32 encoded reference to address at
  72                    // address table offset <index>
  73     ABS32 = 4,     // ABS32 <index> - emit abs32 encoded reference to address at
  74                    // address table offset <index>
  75     MAKE_PE_RELOCATION_TABLE = 5,  // Emit PE base relocation table blocks.
  76     MAKE_ELF_RELOCATION_TABLE = 6, // Emit Elf relocation table for X86
  77     MAKE_ELF_ARM_RELOCATION_TABLE = 7, // Emit Elf relocation table for ARM
  78     // ARM reserves 0x1000-LAST_ARM, bits 13-16 define the opcode
  79     // subset, and 1-12 are the compressed ARM op.
  80     REL32ARM8   = 0x1000,
  81     REL32ARM11  = 0x2000,
  82     REL32ARM24  = 0x3000,
  83     REL32ARM25  = 0x4000,
  84     REL32ARM21  = 0x5000,
  85     LAST_ARM    = 0x5FFF,
  86   };
  87
  88   typedef NoThrowBuffer<RVA> RvaVector;
  89   typedef NoThrowBuffer<uint32> UInt32Vector;
  90   typedef NoThrowBuffer<uint8> UInt8Vector;
  91   typedef NoThrowBuffer<OP> OPVector;
  92
  93   void DebuggingSummary();
  94   CheckBool GeneratePeRelocations(SinkStream *buffer) WARN_UNUSED_RESULT;
  95   CheckBool GenerateElfRelocations(Elf32_Word pending_elf_relocation_table,
  96                                    SinkStream *buffer) WARN_UNUSED_RESULT;
  97   CheckBool DefineLabelCommon(RvaVector*, int, RVA) WARN_UNUSED_RESULT;
  98   void FinishLabelsCommon(RvaVector* addresses);
  99
 100   // Decodes and evaluates courgette ops for ARM rel32 addresses.
 101   CheckBool EvaluateRel32ARM(OP op, size_t& ix_rel32_ix, RVA& current_rva,
 102                              SinkStream* output);
 103
 104   // Binary assembly language tables.
 105   uint64 image_base_;
 106   RvaVector rel32_rva_;
 107   RvaVector abs32_rva_;
 108   OPVector ops_;
 109   RvaVector origins_;
 110   UInt32Vector copy_counts_;
 111   UInt8Vector copy_bytes_;
 112   UInt32Vector rel32_ix_;
 113   UInt32Vector abs32_ix_;
 114
 115   // Table of the addresses containing abs32 relocations; computed during
 116   // assembly, used to generate base relocation table.
 117   UInt32Vector abs32_relocs_;
 118
 119   DISALLOW_COPY_AND_ASSIGN(EncodedProgram);
 120 };
 121
 122 }  // namespace courgette
 123 #endif  // COURGETTE_ENCODED_PROGRAM_H_