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Diffstat (limited to 'courgette/disassembler_win32_x86.cc')
| -rw-r--r-- | courgette/disassembler_win32_x86.cc | 377 |
1 files changed, 0 insertions, 377 deletions
diff --git a/courgette/disassembler_win32_x86.cc b/courgette/disassembler_win32_x86.cc deleted file mode 100644 index fb12c22..0000000 --- a/courgette/disassembler_win32_x86.cc +++ /dev/null @@ -1,377 +0,0 @@ -// Copyright (c) 2011 The Chromium Authors. All rights reserved. -// Use of this source code is governed by a BSD-style license that can be -// found in the LICENSE file. - -#include "courgette/disassembler_win32_x86.h" - -#include <algorithm> -#include <string> -#include <vector> - -#include "base/basictypes.h" -#include "base/logging.h" - -#include "courgette/assembly_program.h" -#include "courgette/courgette.h" -#include "courgette/encoded_program.h" -#include "courgette/image_info.h" - -// COURGETTE_HISTOGRAM_TARGETS prints out a histogram of how frequently -// different target addresses are referenced. Purely for debugging. -#define COURGETTE_HISTOGRAM_TARGETS 0 - -namespace courgette { - -DisassemblerWin32X86::DisassemblerWin32X86(PEInfo* pe_info) - : pe_info_(pe_info), - incomplete_disassembly_(false) { -} - -bool DisassemblerWin32X86::Disassemble(AssemblyProgram* target) { - if (!pe_info().ok()) - return false; - - target->set_image_base(pe_info().image_base()); - - if (!ParseAbs32Relocs()) - return false; - - ParseRel32RelocsFromSections(); - - if (!ParseFile(target)) - return false; - - target->DefaultAssignIndexes(); - - return true; -} - -static uint32 Read32LittleEndian(const void* address) { - return *reinterpret_cast<const uint32*>(address); -} - -bool DisassemblerWin32X86::ParseAbs32Relocs() { - abs32_locations_.clear(); - if (!pe_info().ParseRelocs(&abs32_locations_)) - return false; - - std::sort(abs32_locations_.begin(), abs32_locations_.end()); - -#if COURGETTE_HISTOGRAM_TARGETS - for (size_t i = 0; i < abs32_locations_.size(); ++i) { - RVA rva = abs32_locations_[i]; - // The 4 bytes at the relocation are a reference to some address. - uint32 target_address = Read32LittleEndian(pe_info().RVAToPointer(rva)); - ++abs32_target_rvas_[target_address - pe_info().image_base()]; - } -#endif - return true; -} - -void DisassemblerWin32X86::ParseRel32RelocsFromSections() { - uint32 file_offset = 0; - while (file_offset < pe_info().length()) { - const Section* section = pe_info().FindNextSection(file_offset); - if (section == NULL) - break; - if (file_offset < section->file_offset_of_raw_data) - file_offset = section->file_offset_of_raw_data; - ParseRel32RelocsFromSection(section); - file_offset += section->size_of_raw_data; - } - std::sort(rel32_locations_.begin(), rel32_locations_.end()); - -#if COURGETTE_HISTOGRAM_TARGETS - VLOG(1) << "abs32_locations_ " << abs32_locations_.size() - << "\nrel32_locations_ " << rel32_locations_.size() - << "\nabs32_target_rvas_ " << abs32_target_rvas_.size() - << "\nrel32_target_rvas_ " << rel32_target_rvas_.size(); - - int common = 0; - std::map<RVA, int>::iterator abs32_iter = abs32_target_rvas_.begin(); - std::map<RVA, int>::iterator rel32_iter = rel32_target_rvas_.begin(); - while (abs32_iter != abs32_target_rvas_.end() && - rel32_iter != rel32_target_rvas_.end()) { - if (abs32_iter->first < rel32_iter->first) - ++abs32_iter; - else if (rel32_iter->first < abs32_iter->first) - ++rel32_iter; - else { - ++common; - ++abs32_iter; - ++rel32_iter; - } - } - VLOG(1) << "common " << common; -#endif -} - -void DisassemblerWin32X86::ParseRel32RelocsFromSection(const Section* section) { - // TODO(sra): use characteristic. - bool isCode = strcmp(section->name, ".text") == 0; - if (!isCode) - return; - - uint32 start_file_offset = section->file_offset_of_raw_data; - uint32 end_file_offset = start_file_offset + section->size_of_raw_data; - RVA relocs_start_rva = pe_info().base_relocation_table().address_; - - const uint8* start_pointer = pe_info().FileOffsetToPointer(start_file_offset); - const uint8* end_pointer = pe_info().FileOffsetToPointer(end_file_offset); - - RVA start_rva = pe_info().FileOffsetToRVA(start_file_offset); - RVA end_rva = start_rva + section->virtual_size; - - // Quick way to convert from Pointer to RVA within a single Section is to - // subtract 'pointer_to_rva'. - const uint8* const adjust_pointer_to_rva = start_pointer - start_rva; - - std::vector<RVA>::iterator abs32_pos = abs32_locations_.begin(); - - // Find the rel32 relocations. - const uint8* p = start_pointer; - while (p < end_pointer) { - RVA current_rva = static_cast<RVA>(p - adjust_pointer_to_rva); - if (current_rva == relocs_start_rva) { - uint32 relocs_size = pe_info().base_relocation_table().size_; - if (relocs_size) { - p += relocs_size; - continue; - } - } - - //while (abs32_pos != abs32_locations_.end() && *abs32_pos < current_rva) - // ++abs32_pos; - - // Heuristic discovery of rel32 locations in instruction stream: are the - // next few bytes the start of an instruction containing a rel32 - // addressing mode? - const uint8* rel32 = NULL; - - if (p + 5 < end_pointer) { - if (*p == 0xE8 || *p == 0xE9) { // jmp rel32 and call rel32 - rel32 = p + 1; - } - } - if (p + 6 < end_pointer) { - if (*p == 0x0F && (*(p+1) & 0xF0) == 0x80) { // Jcc long form - if (p[1] != 0x8A && p[1] != 0x8B) // JPE/JPO unlikely - rel32 = p + 2; - } - } - if (rel32) { - RVA rel32_rva = static_cast<RVA>(rel32 - adjust_pointer_to_rva); - - // Is there an abs32 reloc overlapping the candidate? - while (abs32_pos != abs32_locations_.end() && *abs32_pos < rel32_rva - 3) - ++abs32_pos; - // Now: (*abs32_pos > rel32_rva - 4) i.e. the lowest addressed 4-byte - // region that could overlap rel32_rva. - if (abs32_pos != abs32_locations_.end()) { - if (*abs32_pos < rel32_rva + 4) { - // Beginning of abs32 reloc is before end of rel32 reloc so they - // overlap. Skip four bytes past the abs32 reloc. - p += (*abs32_pos + 4) - current_rva; - continue; - } - } - - RVA target_rva = rel32_rva + 4 + Read32LittleEndian(rel32); - // To be valid, rel32 target must be within image, and within this - // section. - if (pe_info().IsValidRVA(target_rva) && - start_rva <= target_rva && target_rva < end_rva) { - rel32_locations_.push_back(rel32_rva); -#if COURGETTE_HISTOGRAM_TARGETS - ++rel32_target_rvas_[target_rva]; -#endif - p += 4; - continue; - } - } - p += 1; - } -} - -CheckBool DisassemblerWin32X86::ParseFile(AssemblyProgram* program) { - bool ok = true; - // Walk all the bytes in the file, whether or not in a section. - uint32 file_offset = 0; - while (ok && file_offset < pe_info().length()) { - const Section* section = pe_info().FindNextSection(file_offset); - if (section == NULL) { - // No more sections. There should not be extra stuff following last - // section. - // ParseNonSectionFileRegion(file_offset, pe_info().length(), program); - break; - } - if (file_offset < section->file_offset_of_raw_data) { - uint32 section_start_offset = section->file_offset_of_raw_data; - ok = ParseNonSectionFileRegion(file_offset, section_start_offset, - program); - file_offset = section_start_offset; - } - if (ok) { - uint32 end = file_offset + section->size_of_raw_data; - ok = ParseFileRegion(section, file_offset, end, program); - file_offset = end; - } - } - -#if COURGETTE_HISTOGRAM_TARGETS - HistogramTargets("abs32 relocs", abs32_target_rvas_); - HistogramTargets("rel32 relocs", rel32_target_rvas_); -#endif - - return ok; -} - -CheckBool DisassemblerWin32X86::ParseNonSectionFileRegion( - uint32 start_file_offset, - uint32 end_file_offset, - AssemblyProgram* program) { - if (incomplete_disassembly_) - return true; - - const uint8* start = pe_info().FileOffsetToPointer(start_file_offset); - const uint8* end = pe_info().FileOffsetToPointer(end_file_offset); - - const uint8* p = start; - - bool ok = true; - while (p < end && ok) { - ok = program->EmitByteInstruction(*p); - ++p; - } - - return ok; -} - -CheckBool DisassemblerWin32X86::ParseFileRegion( - const Section* section, - uint32 start_file_offset, uint32 end_file_offset, - AssemblyProgram* program) { - RVA relocs_start_rva = pe_info().base_relocation_table().address_; - - const uint8* start_pointer = pe_info().FileOffsetToPointer(start_file_offset); - const uint8* end_pointer = pe_info().FileOffsetToPointer(end_file_offset); - - RVA start_rva = pe_info().FileOffsetToRVA(start_file_offset); - RVA end_rva = start_rva + section->virtual_size; - - // Quick way to convert from Pointer to RVA within a single Section is to - // subtract 'pointer_to_rva'. - const uint8* const adjust_pointer_to_rva = start_pointer - start_rva; - - std::vector<RVA>::iterator rel32_pos = rel32_locations_.begin(); - std::vector<RVA>::iterator abs32_pos = abs32_locations_.begin(); - - bool ok = program->EmitOriginInstruction(start_rva); - - const uint8* p = start_pointer; - - while (ok && p < end_pointer) { - RVA current_rva = static_cast<RVA>(p - adjust_pointer_to_rva); - - // The base relocation table is usually in the .relocs section, but it could - // actually be anywhere. Make sure we skip it because we will regenerate it - // during assembly. - if (current_rva == relocs_start_rva) { - ok = program->EmitMakeRelocsInstruction(); - if (!ok) - break; - uint32 relocs_size = pe_info().base_relocation_table().size_; - if (relocs_size) { - p += relocs_size; - continue; - } - } - - while (abs32_pos != abs32_locations_.end() && *abs32_pos < current_rva) - ++abs32_pos; - - if (abs32_pos != abs32_locations_.end() && *abs32_pos == current_rva) { - uint32 target_address = Read32LittleEndian(p); - RVA target_rva = target_address - pe_info().image_base(); - // TODO(sra): target could be Label+offset. It is not clear how to guess - // which it might be. We assume offset==0. - ok = program->EmitAbs32(program->FindOrMakeAbs32Label(target_rva)); - if (!ok) - break; - p += 4; - continue; - } - - while (rel32_pos != rel32_locations_.end() && *rel32_pos < current_rva) - ++rel32_pos; - - if (rel32_pos != rel32_locations_.end() && *rel32_pos == current_rva) { - RVA target_rva = current_rva + 4 + Read32LittleEndian(p); - ok = program->EmitRel32(program->FindOrMakeRel32Label(target_rva)); - p += 4; - continue; - } - - if (incomplete_disassembly_) { - if ((abs32_pos == abs32_locations_.end() || end_rva <= *abs32_pos) && - (rel32_pos == rel32_locations_.end() || end_rva <= *rel32_pos) && - (end_rva <= relocs_start_rva || current_rva >= relocs_start_rva)) { - // No more relocs in this section, don't bother encoding bytes. - break; - } - } - - ok = program->EmitByteInstruction(*p); - p += 1; - } - - return ok; -} - -#if COURGETTE_HISTOGRAM_TARGETS -// Histogram is printed to std::cout. It is purely for debugging the algorithm -// and is only enabled manually in 'exploration' builds. I don't want to add -// command-line configuration for this feature because this code has to be -// small, which means compiled-out. -void DisassemblerWin32X86::HistogramTargets(const char* kind, - const std::map<RVA, int>& map) { - int total = 0; - std::map<int, std::vector<RVA> > h; - for (std::map<RVA, int>::const_iterator p = map.begin(); - p != map.end(); - ++p) { - h[p->second].push_back(p->first); - total += p->second; - } - - std::cout << total << " " << kind << " to " - << map.size() << " unique targets" << std::endl; - - std::cout << "indegree: #targets-with-indegree (example)" << std::endl; - const int kFirstN = 15; - bool someSkipped = false; - int index = 0; - for (std::map<int, std::vector<RVA> >::reverse_iterator p = h.rbegin(); - p != h.rend(); - ++p) { - ++index; - if (index <= kFirstN || p->first <= 3) { - if (someSkipped) { - std::cout << "..." << std::endl; - } - size_t count = p->second.size(); - std::cout << std::dec << p->first << ": " << count; - if (count <= 2) { - for (size_t i = 0; i < count; ++i) - std::cout << " " << pe_info().DescribeRVA(p->second[i]); - } - std::cout << std::endl; - someSkipped = false; - } else { - someSkipped = true; - } - } -} -#endif // COURGETTE_HISTOGRAM_TARGETS - -} // namespace courgette |