/*************************************************************************************************** Zyan Disassembler Library (Zydis) Original Author : Florian Bernd * Permission is hereby granted, free of charge, to any person obtaining a copy * of this software and associated documentation files (the "Software"), to deal * in the Software without restriction, including without limitation the rights * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell * copies of the Software, and to permit persons to whom the Software is * furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included in all * copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE * SOFTWARE. ***************************************************************************************************/ /** * @file * @brief Demonstrates the hooking functionality of the @c ZydisInstructionFormatter class. * * This example demonstrates the hooking functionality of the @c ZydisInstructionFormatter class by * rewriting the mnemonics of (V)CMPPS and (V)CMPPD to their corresponding alias-forms (based on * the condition encoded in the immediate operand). */ #include #include #include "FormatHelper.h" #include #include /* ============================================================================================== */ /* Static data */ /* ============================================================================================== */ /** * @brief Static array with the condition-code strings. */ static const char* conditionCodeStrings[0x20] = { /*00*/ "eq", /*01*/ "lt", /*02*/ "le", /*03*/ "unord", /*04*/ "neq", /*05*/ "nlt", /*06*/ "nle", /*07*/ "ord", /*08*/ "eq_uq", /*09*/ "nge", /*0A*/ "ngt", /*0B*/ "false", /*0C*/ "oq", /*0D*/ "ge", /*0E*/ "gt", /*0F*/ "true", /*10*/ "eq_os", /*11*/ "lt_oq", /*12*/ "le_oq", /*13*/ "unord_s", /*14*/ "neq_us", /*15*/ "nlt_uq", /*16*/ "nle_uq", /*17*/ "ord_s", /*18*/ "eq_us", /*19*/ "nge_uq", /*1A*/ "ngt_uq", /*1B*/ "false_os", /*1C*/ "neq_os", /*1D*/ "ge_oq", /*1E*/ "gt_oq", /*1F*/ "true_us" }; /* ============================================================================================== */ /* Hook callbacks */ /* ============================================================================================== */ ZydisFormatterFormatFunc defaultPrintMnemonic; static ZydisStatus ZydisFormatterPrintMnemonic(ZydisInstructionFormatter* formatter, char** buffer, size_t bufferLen, ZydisInstructionInfo* info) { // We use the user-data field of the instruction-info to pass data to the // @c ZydisFormatterFormatOperandImm function. // In this case we are using a simple ordinal value, but you could pass a pointer to a // complex datatype as well. info->userData = (void*)1; // Rewrite the instruction-mnemonic for the given instructions if ((info->operandCount == 3) && (info->operands[2].type == ZYDIS_OPERAND_TYPE_IMMEDIATE)) { uint8_t conditionCode = info->operands[2].imm.value.ubyte; if (conditionCode < 0x08) { switch (info->mnemonic) { case ZYDIS_MNEMONIC_CMPPS: return ZydisStringBufferAppendFormat(buffer, bufferLen, ZYDIS_STRBUF_APPEND_MODE_DEFAULT, "cmp%sps", conditionCodeStrings[conditionCode]); case ZYDIS_MNEMONIC_CMPPD: return ZydisStringBufferAppendFormat(buffer, bufferLen, ZYDIS_STRBUF_APPEND_MODE_DEFAULT, "cmp%spd", conditionCodeStrings[conditionCode]); default: break; } } } if ((info->operandCount == 4) && (info->operands[3].type == ZYDIS_OPERAND_TYPE_IMMEDIATE)) { uint8_t conditionCode = info->operands[3].imm.value.ubyte; if (conditionCode < 0x20) { switch (info->mnemonic) { case ZYDIS_MNEMONIC_VCMPPS: return ZydisStringBufferAppendFormat(buffer, bufferLen, ZYDIS_STRBUF_APPEND_MODE_DEFAULT, "vcmp%sps", conditionCodeStrings[conditionCode]); case ZYDIS_MNEMONIC_VCMPPD: return ZydisStringBufferAppendFormat(buffer, bufferLen, ZYDIS_STRBUF_APPEND_MODE_DEFAULT, "vcmp%spd", conditionCodeStrings[conditionCode]); default: break; } } } // We did not rewrite the instruction-mnemonic. Signal the @c ZydisFormatterFormatOperandImm // function not to omit the operand info->userData = (void*)0; // Default mnemonic printing return defaultPrintMnemonic(formatter, buffer, bufferLen, info); } /* ---------------------------------------------------------------------------------------------- */ ZydisFormatterFormatOperandFunc defaultFormatOperandImm; static ZydisStatus ZydisFormatterFormatOperandImm(ZydisInstructionFormatter* formatter, char** buffer, size_t bufferLen, ZydisInstructionInfo* info, ZydisOperandInfo* operand) { // The @c ZydisFormatterFormatMnemonic sinals us to omit the immediate (condition-code) // operand, because it got replaced by the alias-mnemonic if ((uintptr_t)info->userData == 1) { // The formatter will automatically omit the operand, if the buffer remains unchanged // after the callback returns return ZYDIS_STATUS_SUCCESS; } // Default immediate formatting return defaultFormatOperandImm(formatter, buffer, bufferLen, info, operand); } /* ---------------------------------------------------------------------------------------------- */ /* ============================================================================================== */ /* Helper functions */ /* ============================================================================================== */ void disassembleBuffer(uint8_t* data, size_t length, ZydisBool installHooks) { ZydisInstructionDecoder decoder; ZydisDecoderInitInstructionDecoder(&decoder, ZYDIS_DISASSEMBLER_MODE_64BIT); ZydisInstructionFormatter formatter; ZydisFormatterInitInstructionFormatterEx(&formatter, ZYDIS_FORMATTER_STYLE_INTEL, ZYDIS_FMTFLAG_FORCE_SEGMENTS | ZYDIS_FMTFLAG_FORCE_OPERANDSIZE, ZYDIS_FORMATTER_ADDR_ABSOLUTE, ZYDIS_FORMATTER_DISP_DEFAULT, ZYDIS_FORMATTER_IMM_DEFAULT); if (installHooks) { defaultPrintMnemonic = &ZydisFormatterPrintMnemonic; ZydisFormatterSetHook(&formatter, ZYDIS_FORMATTER_HOOK_PRINT_MNEMONIC, (const void**)&defaultPrintMnemonic); defaultFormatOperandImm = &ZydisFormatterFormatOperandImm; ZydisFormatterSetHook(&formatter, ZYDIS_FORMATTER_HOOK_FORMAT_OPERAND_IMM, (const void**)&defaultFormatOperandImm); } uint64_t instructionPointer = 0x007FFFFFFF400000; ZydisInstructionInfo info; char buffer[256]; while (ZYDIS_SUCCESS( ZydisDecoderDecodeInstruction(&decoder, data, length, instructionPointer, &info))) { data += info.length; length -= info.length; instructionPointer += info.length; printf("%016" PRIX64 " ", info.instrAddress); ZydisFormatterFormatInstruction(&formatter, &info, &buffer[0], sizeof(buffer)); printf(" %s\n", &buffer[0]); } } /* ============================================================================================== */ /* Entry point */ /* ============================================================================================== */ int main() { uint8_t data[] = { // cmpps xmm1, xmm4, 0x03 0x0F, 0xC2, 0xCC, 0x03, // vcmpord_spd xmm1, xmm2, xmm3 0xC5, 0xE9, 0xC2, 0xCB, 0x17, // vcmpps k2 {k7}, zmm2, dword ptr ds:[rax + rbx*4 + 0x100] {1to16}, 0x0F 0x62, 0xF1, 0x6C, 0x5F, 0xC2, 0x54, 0x98, 0x40, 0x0F }; disassembleBuffer(&data[0], sizeof(data), ZYDIS_FALSE); puts(""); disassembleBuffer(&data[0], sizeof(data), ZYDIS_TRUE); getchar(); return 0; } /* ============================================================================================== */