n>(program& p) { for (int i = 0; i < SIZE(p.segments); ++i) { if (p.segments.at(i).name != "code") drop_labels(p.segments.at(i)); } } void replace_global_variables_with_addresses(program& p, const map<string, uint32_t>& address) { if (p.segments.empty()) return; for (int i = 0; i < SIZE(p.segments); ++i) { segment& curr = p.segments.at(i); if (curr.name == "code") replace_global_variables_in_code_segment(curr, address); else replace_global_variables_in_data_segment(curr, address); } } void replace_global_variables_in_code_segment(segment& code, const map<string, uint32_t>& address) { for (int i = 0; i < SIZE(code.lines); ++i) { line& inst = code.lines.at(i); line new_inst; for (int j = 0; j < SIZE(inst.words); ++j) { const word& curr = inst.words.at(j); if (!contains_key(address, curr.data)) { if (!looks_like_hex_int(curr.data)) raise << "missing reference to global '" << curr.data << "'\n" << end(); new_inst.words.push_back(curr); continue; } if (!valid_use_of_global_variable(curr)) { raise << "'" << to_string(inst) << "': can't refer to global variable '" << curr.data << "'\n" << end(); return; } emit_hex_bytes(new_inst, get(address, curr.data), 4); } inst.words.swap(new_inst.words); trace(99, "transform") << "instruction after transform: '" << data_to_string(inst) << "'" << end(); } } void replace_global_variables_in_data_segment(segment& data, const map<string, uint32_t>& address) { for (int i = 0; i < SIZE(data.lines); ++i) { line& l = data.lines.at(i); line new_l; for (int j = 0; j < SIZE(l.words); ++j) { const word& curr = l.words.at(j); if (!contains_key(address, curr.data)) { if (looks_like_hex_int(curr.data)) { if (has_operand_metadata(curr, "imm32")) emit_hex_bytes(new_l, curr, 4); else if (has_operand_metadata(curr, "imm16")) emit_hex_bytes(new_l, curr, 2); else if (has_operand_metadata(curr, "imm8")) emit_hex_bytes(new_l, curr, 1); else if (has_operand_metadata(curr, "disp8")) raise << "can't use /disp8 in a non-code segment\n" << end(); else if (has_operand_metadata(curr, "disp16")) raise << "can't use /disp16 in a non-code segment\n" << end(); else if (has_operand_metadata(curr, "disp32")) raise << "can't use /disp32 in a non-code segment\n" << end(); else new_l.words.push_back(curr); } else { raise << "missing reference to global '" << curr.data << "'\n" << end(); new_l.words.push_back(curr); } continue; } trace(99, "transform") << curr.data << " maps to " << HEXWORD << get(address, curr.data) << end(); emit_hex_bytes(new_l, get(address, curr.data), 4); } l.words.swap(new_l.words); trace(99, "transform") << "after transform: '" << data_to_string(l) << "'" << end(); } } bool valid_use_of_global_variable(const word& curr) { if (has_operand_metadata(curr, "imm32")) return true; // End Valid Uses Of Global Variable(curr) return false; } //:: a more complex sanity check for how we use global variables //: requires first saving some data early before we pack operands :(after "Begin Level-2 Transforms") Transform.push_back(correlate_disp32_with_mod); :(code) void correlate_disp32_with_mod(program& p) { if (p.segments.empty()) return; segment& code = *find(p, "code"); for (int i = 0; i < SIZE(code.lines); ++i) { line& inst = code.lines.at(i); for (int j = 0; j < SIZE(inst.words); ++j) { word& curr = inst.words.at(j); if (has_operand_metadata(curr, "disp32") && has_operand_metadata(inst, "mod")) curr.metadata.push_back("has_mod"); } } } :(before "End Valid Uses Of Global Variable(curr)") if (has_operand_metadata(curr, "disp32")) return has_metadata(curr, "has_mod"); // todo: more sophisticated check, to ensure we don't use global variable // addresses as a real displacement added to other operands. :(code) bool has_metadata(const word& w, const string& m) { for (int i = 0; i < SIZE(w.metadata); ++i) if (w.metadata.at(i) == m) return true; return false; } void test_global_variable_disallowed_in_jump() { Hide_errors = true; run( "== code 0x1\n" "eb/jump x/disp8\n" "== data 0x2000\n" "x:\n" " 00 00 00 00\n" ); CHECK_TRACE_CONTENTS( "error: 'eb/jump x/disp8': can't refer to global variable 'x'\n" // sub-optimal error message; should be //? "error: can't jump to data (variable 'x')\n" ); } void test_global_variable_disallowed_in_call() { Hide_errors = true; run( "== code 0x1\n" "e8/call x/disp32\n" "== data 0x2000\n" "x:\n" " 00 00 00 00\n" ); CHECK_TRACE_CONTENTS( "error: 'e8/call x/disp32': can't refer to global variable 'x'\n" // sub-optimal error message; should be //? "error: can't call to the data segment ('x')\n" ); } void test_global_variable_in_data_segment() { run( "== code 0x1\n" "b9 x/imm32\n" "== data 0x2000\n" "x:\n" " y/imm32\n" "y:\n" " 00 00 00 00\n" ); // check that we loaded 'x' with the address of 'y' CHECK_TRACE_CONTENTS( "load: 0x00002000 -> 04\n" "load: 0x00002001 -> 20\n" "load: 0x00002002 -> 00\n" "load: 0x00002003 -> 00\n" ); CHECK_TRACE_COUNT("error", 0); } void test_raw_number_with_imm32_in_data_segment() { run( "== code 0x1\n" "b9 x/imm32\n" "== data 0x2000\n" "x:\n" " 1/imm32\n" ); // check that we loaded 'x' with the address of 1 CHECK_TRACE_CONTENTS( "load: 0x00002000 -> 01\n" "load: 0x00002001 -> 00\n" "load: 0x00002002 -> 00\n" "load: 0x00002003 -> 00\n" ); CHECK_TRACE_COUNT("error", 0); } void test_duplicate_global_variable() { Hide_errors = true; run( "== code 0x1\n" "40/increment-EAX\n" "== data 0x2000\n" "x:\n" "x:\n" " 00\n" ); CHECK_TRACE_CONTENTS( "error: duplicate global 'x'\n" ); } void test_global_variable_disp32_with_modrm() { run( "== code 0x1\n" "8b/copy 0/mod/indirect 5/rm32/.disp32 2/r32/EDX x/disp32\n" "== data 0x2000\n" "x:\n" " 00 00 00 00\n" ); CHECK_TRACE_COUNT("error", 0); } void test_global_variable_disp32_with_call() { transform( "== code 0x1\n" "foo:\n" " e8/call bar/disp32\n" "bar:\n" ); CHECK_TRACE_COUNT("error", 0); } string to_full_string(const line& in) { ostringstream out; for (int i = 0; i < SIZE(in.words); ++i) { if (i > 0) out << ' '; out << in.words.at(i).data; for (int j = 0; j < SIZE(in.words.at(i).metadata); ++j) out << '/' << in.words.at(i).metadata.at(j); } return out.str(); }