//===-- DWARFExpression.cpp -----------------------------------------------===// // // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. // See https://llvm.org/LICENSE.txt for license information. // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception // //===----------------------------------------------------------------------===// #include "lldb/Expression/DWARFExpression.h" #include #include #include "lldb/Core/Module.h" #include "lldb/Core/Value.h" #include "lldb/Core/dwarf.h" #include "lldb/Utility/DataEncoder.h" #include "lldb/Utility/LLDBLog.h" #include "lldb/Utility/Log.h" #include "lldb/Utility/RegisterValue.h" #include "lldb/Utility/Scalar.h" #include "lldb/Utility/StreamString.h" #include "lldb/Utility/VMRange.h" #include "lldb/Host/Host.h" #include "lldb/Utility/Endian.h" #include "lldb/Symbol/Function.h" #include "lldb/Target/ABI.h" #include "lldb/Target/ExecutionContext.h" #include "lldb/Target/Process.h" #include "lldb/Target/RegisterContext.h" #include "lldb/Target/StackFrame.h" #include "lldb/Target/StackID.h" #include "lldb/Target/Target.h" #include "lldb/Target/Thread.h" #include "llvm/DebugInfo/DWARF/DWARFDebugLoc.h" #include "llvm/DebugInfo/DWARF/DWARFExpression.h" #include "Plugins/SymbolFile/DWARF/DWARFUnit.h" using namespace lldb; using namespace lldb_private; using namespace lldb_private::dwarf; // DWARFExpression constructor DWARFExpression::DWARFExpression() : m_data() {} DWARFExpression::DWARFExpression(const DataExtractor &data) : m_data(data) {} // Destructor DWARFExpression::~DWARFExpression() = default; bool DWARFExpression::IsValid() const { return m_data.GetByteSize() > 0; } void DWARFExpression::UpdateValue(uint64_t const_value, lldb::offset_t const_value_byte_size, uint8_t addr_byte_size) { if (!const_value_byte_size) return; m_data.SetData( DataBufferSP(new DataBufferHeap(&const_value, const_value_byte_size))); m_data.SetByteOrder(endian::InlHostByteOrder()); m_data.SetAddressByteSize(addr_byte_size); } void DWARFExpression::DumpLocation(Stream *s, lldb::DescriptionLevel level, ABI *abi) const { llvm::DWARFExpression(m_data.GetAsLLVM(), m_data.GetAddressByteSize()) .print(s->AsRawOstream(), llvm::DIDumpOptions(), abi ? &abi->GetMCRegisterInfo() : nullptr, nullptr); } RegisterKind DWARFExpression::GetRegisterKind() const { return m_reg_kind; } void DWARFExpression::SetRegisterKind(RegisterKind reg_kind) { m_reg_kind = reg_kind; } static bool ReadRegisterValueAsScalar(RegisterContext *reg_ctx, lldb::RegisterKind reg_kind, uint32_t reg_num, Status *error_ptr, Value &value) { if (reg_ctx == nullptr) { if (error_ptr) error_ptr->SetErrorString("No register context in frame.\n"); } else { uint32_t native_reg = reg_ctx->ConvertRegisterKindToRegisterNumber(reg_kind, reg_num); if (native_reg == LLDB_INVALID_REGNUM) { if (error_ptr) error_ptr->SetErrorStringWithFormat("Unable to convert register " "kind=%u reg_num=%u to a native " "register number.\n", reg_kind, reg_num); } else { const RegisterInfo *reg_info = reg_ctx->GetRegisterInfoAtIndex(native_reg); RegisterValue reg_value; if (reg_ctx->ReadRegister(reg_info, reg_value)) { if (reg_value.GetScalarValue(value.GetScalar())) { value.SetValueType(Value::ValueType::Scalar); value.SetContext(Value::ContextType::RegisterInfo, const_cast(reg_info)); if (error_ptr) error_ptr->Clear(); return true; } else { // If we get this error, then we need to implement a value buffer in // the dwarf expression evaluation function... if (error_ptr) error_ptr->SetErrorStringWithFormat( "register %s can't be converted to a scalar value", reg_info->name); } } else { if (error_ptr) error_ptr->SetErrorStringWithFormat("register %s is not available", reg_info->name); } } } return false; } /// Return the length in bytes of the set of operands for \p op. No guarantees /// are made on the state of \p data after this call. static offset_t GetOpcodeDataSize(const DataExtractor &data, const lldb::offset_t data_offset, const uint8_t op) { lldb::offset_t offset = data_offset; switch (op) { case DW_OP_addr: case DW_OP_call_ref: // 0x9a 1 address sized offset of DIE (DWARF3) return data.GetAddressByteSize(); // Opcodes with no arguments case DW_OP_deref: // 0x06 case DW_OP_dup: // 0x12 case DW_OP_drop: // 0x13 case DW_OP_over: // 0x14 case DW_OP_swap: // 0x16 case DW_OP_rot: // 0x17 case DW_OP_xderef: // 0x18 case DW_OP_abs: // 0x19 case DW_OP_and: // 0x1a case DW_OP_div: // 0x1b case DW_OP_minus: // 0x1c case DW_OP_mod: // 0x1d case DW_OP_mul: // 0x1e case DW_OP_neg: // 0x1f case DW_OP_not: // 0x20 case DW_OP_or: // 0x21 case DW_OP_plus: // 0x22 case DW_OP_shl: // 0x24 case DW_OP_shr: // 0x25 case DW_OP_shra: // 0x26 case DW_OP_xor: // 0x27 case DW_OP_eq: // 0x29 case DW_OP_ge: // 0x2a case DW_OP_gt: // 0x2b case DW_OP_le: // 0x2c case DW_OP_lt: // 0x2d case DW_OP_ne: // 0x2e case DW_OP_lit0: // 0x30 case DW_OP_lit1: // 0x31 case DW_OP_lit2: // 0x32 case DW_OP_lit3: // 0x33 case DW_OP_lit4: // 0x34 case DW_OP_lit5: // 0x35 case DW_OP_lit6: // 0x36 case DW_OP_lit7: // 0x37 case DW_OP_lit8: // 0x38 case DW_OP_lit9: // 0x39 case DW_OP_lit10: // 0x3A case DW_OP_lit11: // 0x3B case DW_OP_lit12: // 0x3C case DW_OP_lit13: // 0x3D case DW_OP_lit14: // 0x3E case DW_OP_lit15: // 0x3F case DW_OP_lit16: // 0x40 case DW_OP_lit17: // 0x41 case DW_OP_lit18: // 0x42 case DW_OP_lit19: // 0x43 case DW_OP_lit20: // 0x44 case DW_OP_lit21: // 0x45 case DW_OP_lit22: // 0x46 case DW_OP_lit23: // 0x47 case DW_OP_lit24: // 0x48 case DW_OP_lit25: // 0x49 case DW_OP_lit26: // 0x4A case DW_OP_lit27: // 0x4B case DW_OP_lit28: // 0x4C case DW_OP_lit29: // 0x4D case DW_OP_lit30: // 0x4E case DW_OP_lit31: // 0x4f case DW_OP_reg0: // 0x50 case DW_OP_reg1: // 0x51 case DW_OP_reg2: // 0x52 case DW_OP_reg3: // 0x53 case DW_OP_reg4: // 0x54 case DW_OP_reg5: // 0x55 case DW_OP_reg6: // 0x56 case DW_OP_reg7: // 0x57 case DW_OP_reg8: // 0x58 case DW_OP_reg9: // 0x59 case DW_OP_reg10: // 0x5A case DW_OP_reg11: // 0x5B case DW_OP_reg12: // 0x5C case DW_OP_reg13: // 0x5D case DW_OP_reg14: // 0x5E case DW_OP_reg15: // 0x5F case DW_OP_reg16: // 0x60 case DW_OP_reg17: // 0x61 case DW_OP_reg18: // 0x62 case DW_OP_reg19: // 0x63 case DW_OP_reg20: // 0x64 case DW_OP_reg21: // 0x65 case DW_OP_reg22: // 0x66 case DW_OP_reg23: // 0x67 case DW_OP_reg24: // 0x68 case DW_OP_reg25: // 0x69 case DW_OP_reg26: // 0x6A case DW_OP_reg27: // 0x6B case DW_OP_reg28: // 0x6C case DW_OP_reg29: // 0x6D case DW_OP_reg30: // 0x6E case DW_OP_reg31: // 0x6F case DW_OP_nop: // 0x96 case DW_OP_push_object_address: // 0x97 DWARF3 case DW_OP_form_tls_address: // 0x9b DWARF3 case DW_OP_call_frame_cfa: // 0x9c DWARF3 case DW_OP_stack_value: // 0x9f DWARF4 case DW_OP_GNU_push_tls_address: // 0xe0 GNU extension return 0; // Opcodes with a single 1 byte arguments case DW_OP_const1u: // 0x08 1 1-byte constant case DW_OP_const1s: // 0x09 1 1-byte constant case DW_OP_pick: // 0x15 1 1-byte stack index case DW_OP_deref_size: // 0x94 1 1-byte size of data retrieved case DW_OP_xderef_size: // 0x95 1 1-byte size of data retrieved return 1; // Opcodes with a single 2 byte arguments case DW_OP_const2u: // 0x0a 1 2-byte constant case DW_OP_const2s: // 0x0b 1 2-byte constant case DW_OP_skip: // 0x2f 1 signed 2-byte constant case DW_OP_bra: // 0x28 1 signed 2-byte constant case DW_OP_call2: // 0x98 1 2-byte offset of DIE (DWARF3) return 2; // Opcodes with a single 4 byte arguments case DW_OP_const4u: // 0x0c 1 4-byte constant case DW_OP_const4s: // 0x0d 1 4-byte constant case DW_OP_call4: // 0x99 1 4-byte offset of DIE (DWARF3) return 4; // Opcodes with a single 8 byte arguments case DW_OP_const8u: // 0x0e 1 8-byte constant case DW_OP_const8s: // 0x0f 1 8-byte constant return 8; // All opcodes that have a single ULEB (signed or unsigned) argument case DW_OP_addrx: // 0xa1 1 ULEB128 index case DW_OP_constu: // 0x10 1 ULEB128 constant case DW_OP_consts: // 0x11 1 SLEB128 constant case DW_OP_plus_uconst: // 0x23 1 ULEB128 addend case DW_OP_breg0: // 0x70 1 ULEB128 register case DW_OP_breg1: // 0x71 1 ULEB128 register case DW_OP_breg2: // 0x72 1 ULEB128 register case DW_OP_breg3: // 0x73 1 ULEB128 register case DW_OP_breg4: // 0x74 1 ULEB128 register case DW_OP_breg5: // 0x75 1 ULEB128 register case DW_OP_breg6: // 0x76 1 ULEB128 register case DW_OP_breg7: // 0x77 1 ULEB128 register case DW_OP_breg8: // 0x78 1 ULEB128 register case DW_OP_breg9: // 0x79 1 ULEB128 register case DW_OP_breg10: // 0x7a 1 ULEB128 register case DW_OP_breg11: // 0x7b 1 ULEB128 register case DW_OP_breg12: // 0x7c 1 ULEB128 register case DW_OP_breg13: // 0x7d 1 ULEB128 register case DW_OP_breg14: // 0x7e 1 ULEB128 register case DW_OP_breg15: // 0x7f 1 ULEB128 register case DW_OP_breg16: // 0x80 1 ULEB128 register case DW_OP_breg17: // 0x81 1 ULEB128 register case DW_OP_breg18: // 0x82 1 ULEB128 register case DW_OP_breg19: // 0x83 1 ULEB128 register case DW_OP_breg20: // 0x84 1 ULEB128 register case DW_OP_breg21: // 0x85 1 ULEB128 register case DW_OP_breg22: // 0x86 1 ULEB128 register case DW_OP_breg23: // 0x87 1 ULEB128 register case DW_OP_breg24: // 0x88 1 ULEB128 register case DW_OP_breg25: // 0x89 1 ULEB128 register case DW_OP_breg26: // 0x8a 1 ULEB128 register case DW_OP_breg27: // 0x8b 1 ULEB128 register case DW_OP_breg28: // 0x8c 1 ULEB128 register case DW_OP_breg29: // 0x8d 1 ULEB128 register case DW_OP_breg30: // 0x8e 1 ULEB128 register case DW_OP_breg31: // 0x8f 1 ULEB128 register case DW_OP_regx: // 0x90 1 ULEB128 register case DW_OP_fbreg: // 0x91 1 SLEB128 offset case DW_OP_piece: // 0x93 1 ULEB128 size of piece addressed case DW_OP_GNU_addr_index: // 0xfb 1 ULEB128 index case DW_OP_GNU_const_index: // 0xfc 1 ULEB128 index data.Skip_LEB128(&offset); return offset - data_offset; // All opcodes that have a 2 ULEB (signed or unsigned) arguments case DW_OP_bregx: // 0x92 2 ULEB128 register followed by SLEB128 offset case DW_OP_bit_piece: // 0x9d ULEB128 bit size, ULEB128 bit offset (DWARF3); data.Skip_LEB128(&offset); data.Skip_LEB128(&offset); return offset - data_offset; case DW_OP_implicit_value: // 0x9e ULEB128 size followed by block of that size // (DWARF4) { uint64_t block_len = data.Skip_LEB128(&offset); offset += block_len; return offset - data_offset; } case DW_OP_GNU_entry_value: case DW_OP_entry_value: // 0xa3 ULEB128 size + variable-length block { uint64_t subexpr_len = data.GetULEB128(&offset); return (offset - data_offset) + subexpr_len; } default: break; } return LLDB_INVALID_OFFSET; } lldb::addr_t DWARFExpression::GetLocation_DW_OP_addr(const DWARFUnit *dwarf_cu, uint32_t op_addr_idx, bool &error) const { error = false; lldb::offset_t offset = 0; uint32_t curr_op_addr_idx = 0; while (m_data.ValidOffset(offset)) { const uint8_t op = m_data.GetU8(&offset); if (op == DW_OP_addr) { const lldb::addr_t op_file_addr = m_data.GetAddress(&offset); if (curr_op_addr_idx == op_addr_idx) return op_file_addr; ++curr_op_addr_idx; } else if (op == DW_OP_GNU_addr_index || op == DW_OP_addrx) { uint64_t index = m_data.GetULEB128(&offset); if (curr_op_addr_idx == op_addr_idx) { if (!dwarf_cu) { error = true; break; } return dwarf_cu->ReadAddressFromDebugAddrSection(index); } ++curr_op_addr_idx; } else { const offset_t op_arg_size = GetOpcodeDataSize(m_data, offset, op); if (op_arg_size == LLDB_INVALID_OFFSET) { error = true; break; } offset += op_arg_size; } } return LLDB_INVALID_ADDRESS; } bool DWARFExpression::Update_DW_OP_addr(lldb::addr_t file_addr) { lldb::offset_t offset = 0; while (m_data.ValidOffset(offset)) { const uint8_t op = m_data.GetU8(&offset); if (op == DW_OP_addr) { const uint32_t addr_byte_size = m_data.GetAddressByteSize(); // We have to make a copy of the data as we don't know if this data is // from a read only memory mapped buffer, so we duplicate all of the data // first, then modify it, and if all goes well, we then replace the data // for this expression // Make en encoder that contains a copy of the location expression data // so we can write the address into the buffer using the correct byte // order. DataEncoder encoder(m_data.GetDataStart(), m_data.GetByteSize(), m_data.GetByteOrder(), addr_byte_size); // Replace the address in the new buffer if (encoder.PutAddress(offset, file_addr) == UINT32_MAX) return false; // All went well, so now we can reset the data using a shared pointer to // the heap data so "m_data" will now correctly manage the heap data. m_data.SetData(encoder.GetDataBuffer()); return true; } else { const offset_t op_arg_size = GetOpcodeDataSize(m_data, offset, op); if (op_arg_size == LLDB_INVALID_OFFSET) break; offset += op_arg_size; } } return false; } bool DWARFExpression::ContainsThreadLocalStorage() const { lldb::offset_t offset = 0; while (m_data.ValidOffset(offset)) { const uint8_t op = m_data.GetU8(&offset); if (op == DW_OP_form_tls_address || op == DW_OP_GNU_push_tls_address) return true; const offset_t op_arg_size = GetOpcodeDataSize(m_data, offset, op); if (op_arg_size == LLDB_INVALID_OFFSET) return false; offset += op_arg_size; } return false; } bool DWARFExpression::LinkThreadLocalStorage( std::function const &link_address_callback) { const uint32_t addr_byte_size = m_data.GetAddressByteSize(); // We have to make a copy of the data as we don't know if this data is from a // read only memory mapped buffer, so we duplicate all of the data first, // then modify it, and if all goes well, we then replace the data for this // expression. // Make en encoder that contains a copy of the location expression data so we // can write the address into the buffer using the correct byte order. DataEncoder encoder(m_data.GetDataStart(), m_data.GetByteSize(), m_data.GetByteOrder(), addr_byte_size); lldb::offset_t offset = 0; lldb::offset_t const_offset = 0; lldb::addr_t const_value = 0; size_t const_byte_size = 0; while (m_data.ValidOffset(offset)) { const uint8_t op = m_data.GetU8(&offset); bool decoded_data = false; switch (op) { case DW_OP_const4u: // Remember the const offset in case we later have a // DW_OP_form_tls_address or DW_OP_GNU_push_tls_address const_offset = offset; const_value = m_data.GetU32(&offset); decoded_data = true; const_byte_size = 4; break; case DW_OP_const8u: // Remember the const offset in case we later have a // DW_OP_form_tls_address or DW_OP_GNU_push_tls_address const_offset = offset; const_value = m_data.GetU64(&offset); decoded_data = true; const_byte_size = 8; break; case DW_OP_form_tls_address: case DW_OP_GNU_push_tls_address: // DW_OP_form_tls_address and DW_OP_GNU_push_tls_address must be preceded // by a file address on the stack. We assume that DW_OP_const4u or // DW_OP_const8u is used for these values, and we check that the last // opcode we got before either of these was DW_OP_const4u or // DW_OP_const8u. If so, then we can link the value accodingly. For // Darwin, the value in the DW_OP_const4u or DW_OP_const8u is the file // address of a structure that contains a function pointer, the pthread // key and the offset into the data pointed to by the pthread key. So we // must link this address and also set the module of this expression to // the new_module_sp so we can resolve the file address correctly if (const_byte_size > 0) { lldb::addr_t linked_file_addr = link_address_callback(const_value); if (linked_file_addr == LLDB_INVALID_ADDRESS) return false; // Replace the address in the new buffer if (encoder.PutUnsigned(const_offset, const_byte_size, linked_file_addr) == UINT32_MAX) return false; } break; default: const_offset = 0; const_value = 0; const_byte_size = 0; break; } if (!decoded_data) { const offset_t op_arg_size = GetOpcodeDataSize(m_data, offset, op); if (op_arg_size == LLDB_INVALID_OFFSET) return false; else offset += op_arg_size; } } m_data.SetData(encoder.GetDataBuffer()); return true; } static bool Evaluate_DW_OP_entry_value(std::vector &stack, ExecutionContext *exe_ctx, RegisterContext *reg_ctx, const DataExtractor &opcodes, lldb::offset_t &opcode_offset, Status *error_ptr, Log *log) { // DW_OP_entry_value(sub-expr) describes the location a variable had upon // function entry: this variable location is presumed to be optimized out at // the current PC value. The caller of the function may have call site // information that describes an alternate location for the variable (e.g. a // constant literal, or a spilled stack value) in the parent frame. // // Example (this is pseudo-code & pseudo-DWARF, but hopefully illustrative): // // void child(int &sink, int x) { // ... // /* "x" gets optimized out. */ // // /* The location of "x" here is: DW_OP_entry_value($reg2). */ // ++sink; // } // // void parent() { // int sink; // // /* // * The callsite information emitted here is: // * // * DW_TAG_call_site // * DW_AT_return_pc ... (for "child(sink, 123);") // * DW_TAG_call_site_parameter (for "sink") // * DW_AT_location ($reg1) // * DW_AT_call_value ($SP - 8) // * DW_TAG_call_site_parameter (for "x") // * DW_AT_location ($reg2) // * DW_AT_call_value ($literal 123) // * // * DW_TAG_call_site // * DW_AT_return_pc ... (for "child(sink, 456);") // * ... // */ // child(sink, 123); // child(sink, 456); // } // // When the program stops at "++sink" within `child`, the debugger determines // the call site by analyzing the return address. Once the call site is found, // the debugger determines which parameter is referenced by DW_OP_entry_value // and evaluates the corresponding location for that parameter in `parent`. // 1. Find the function which pushed the current frame onto the stack. if ((!exe_ctx || !exe_ctx->HasTargetScope()) || !reg_ctx) { LLDB_LOG(log, "Evaluate_DW_OP_entry_value: no exe/reg context"); return false; } StackFrame *current_frame = exe_ctx->GetFramePtr(); Thread *thread = exe_ctx->GetThreadPtr(); if (!current_frame || !thread) { LLDB_LOG(log, "Evaluate_DW_OP_entry_value: no current frame/thread"); return false; } Target &target = exe_ctx->GetTargetRef(); StackFrameSP parent_frame = nullptr; addr_t return_pc = LLDB_INVALID_ADDRESS; uint32_t current_frame_idx = current_frame->GetFrameIndex(); uint32_t num_frames = thread->GetStackFrameCount(); for (uint32_t parent_frame_idx = current_frame_idx + 1; parent_frame_idx < num_frames; ++parent_frame_idx) { parent_frame = thread->GetStackFrameAtIndex(parent_frame_idx); // Require a valid sequence of frames. if (!parent_frame) break; // Record the first valid return address, even if this is an inlined frame, // in order to look up the associated call edge in the first non-inlined // parent frame. if (return_pc == LLDB_INVALID_ADDRESS) { return_pc = parent_frame->GetFrameCodeAddress().GetLoadAddress(&target); LLDB_LOG(log, "Evaluate_DW_OP_entry_value: immediate ancestor with pc = {0:x}", return_pc); } // If we've found an inlined frame, skip it (these have no call site // parameters). if (parent_frame->IsInlined()) continue; // We've found the first non-inlined parent frame. break; } if (!parent_frame || !parent_frame->GetRegisterContext()) { LLDB_LOG(log, "Evaluate_DW_OP_entry_value: no parent frame with reg ctx"); return false; } Function *parent_func = parent_frame->GetSymbolContext(eSymbolContextFunction).function; if (!parent_func) { LLDB_LOG(log, "Evaluate_DW_OP_entry_value: no parent function"); return false; } // 2. Find the call edge in the parent function responsible for creating the // current activation. Function *current_func = current_frame->GetSymbolContext(eSymbolContextFunction).function; if (!current_func) { LLDB_LOG(log, "Evaluate_DW_OP_entry_value: no current function"); return false; } CallEdge *call_edge = nullptr; ModuleList &modlist = target.GetImages(); ExecutionContext parent_exe_ctx = *exe_ctx; parent_exe_ctx.SetFrameSP(parent_frame); if (!parent_frame->IsArtificial()) { // If the parent frame is not artificial, the current activation may be // produced by an ambiguous tail call. In this case, refuse to proceed. call_edge = parent_func->GetCallEdgeForReturnAddress(return_pc, target); if (!call_edge) { LLDB_LOG(log, "Evaluate_DW_OP_entry_value: no call edge for retn-pc = {0:x} " "in parent frame {1}", return_pc, parent_func->GetName()); return false; } Function *callee_func = call_edge->GetCallee(modlist, parent_exe_ctx); if (callee_func != current_func) { LLDB_LOG(log, "Evaluate_DW_OP_entry_value: ambiguous call sequence, " "can't find real parent frame"); return false; } } else { // The StackFrameList solver machinery has deduced that an unambiguous tail // call sequence that produced the current activation. The first edge in // the parent that points to the current function must be valid. for (auto &edge : parent_func->GetTailCallingEdges()) { if (edge->GetCallee(modlist, parent_exe_ctx) == current_func) { call_edge = edge.get(); break; } } } if (!call_edge) { LLDB_LOG(log, "Evaluate_DW_OP_entry_value: no unambiguous edge from parent " "to current function"); return false; } // 3. Attempt to locate the DW_OP_entry_value expression in the set of // available call site parameters. If found, evaluate the corresponding // parameter in the context of the parent frame. const uint32_t subexpr_len = opcodes.GetULEB128(&opcode_offset); const void *subexpr_data = opcodes.GetData(&opcode_offset, subexpr_len); if (!subexpr_data) { LLDB_LOG(log, "Evaluate_DW_OP_entry_value: subexpr could not be read"); return false; } const CallSiteParameter *matched_param = nullptr; for (const CallSiteParameter ¶m : call_edge->GetCallSiteParameters()) { DataExtractor param_subexpr_extractor; if (!param.LocationInCallee.GetExpressionData(param_subexpr_extractor)) continue; lldb::offset_t param_subexpr_offset = 0; const void *param_subexpr_data = param_subexpr_extractor.GetData(¶m_subexpr_offset, subexpr_len); if (!param_subexpr_data || param_subexpr_extractor.BytesLeft(param_subexpr_offset) != 0) continue; // At this point, the DW_OP_entry_value sub-expression and the callee-side // expression in the call site parameter are known to have the same length. // Check whether they are equal. // // Note that an equality check is sufficient: the contents of the // DW_OP_entry_value subexpression are only used to identify the right call // site parameter in the parent, and do not require any special handling. if (memcmp(subexpr_data, param_subexpr_data, subexpr_len) == 0) { matched_param = ¶m; break; } } if (!matched_param) { LLDB_LOG(log, "Evaluate_DW_OP_entry_value: no matching call site param found"); return false; } // TODO: Add support for DW_OP_push_object_address within a DW_OP_entry_value // subexpresion whenever llvm does. Value result; const DWARFExpressionList ¶m_expr = matched_param->LocationInCaller; if (!param_expr.Evaluate(&parent_exe_ctx, parent_frame->GetRegisterContext().get(), LLDB_INVALID_ADDRESS, /*initial_value_ptr=*/nullptr, /*object_address_ptr=*/nullptr, result, error_ptr)) { LLDB_LOG(log, "Evaluate_DW_OP_entry_value: call site param evaluation failed"); return false; } stack.push_back(result); return true; } namespace { /// The location description kinds described by the DWARF v5 /// specification. Composite locations are handled out-of-band and /// thus aren't part of the enum. enum LocationDescriptionKind { Empty, Memory, Register, Implicit /* Composite*/ }; /// Adjust value's ValueType according to the kind of location description. void UpdateValueTypeFromLocationDescription(Log *log, const DWARFUnit *dwarf_cu, LocationDescriptionKind kind, Value *value = nullptr) { // Note that this function is conflating DWARF expressions with // DWARF location descriptions. Perhaps it would be better to define // a wrapper for DWARFExpresssion::Eval() that deals with DWARF // location descriptions (which consist of one or more DWARF // expressions). But doing this would mean we'd also need factor the // handling of DW_OP_(bit_)piece out of this function. if (dwarf_cu && dwarf_cu->GetVersion() >= 4) { const char *log_msg = "DWARF location description kind: %s"; switch (kind) { case Empty: LLDB_LOGF(log, log_msg, "Empty"); break; case Memory: LLDB_LOGF(log, log_msg, "Memory"); if (value->GetValueType() == Value::ValueType::Scalar) value->SetValueType(Value::ValueType::LoadAddress); break; case Register: LLDB_LOGF(log, log_msg, "Register"); value->SetValueType(Value::ValueType::Scalar); break; case Implicit: LLDB_LOGF(log, log_msg, "Implicit"); if (value->GetValueType() == Value::ValueType::LoadAddress) value->SetValueType(Value::ValueType::Scalar); break; } } } } // namespace /// Helper function to move common code used to resolve a file address and turn /// into a load address. /// /// \param exe_ctx Pointer to the execution context /// \param module_sp shared_ptr contains the module if we have one /// \param error_ptr pointer to Status object if we have one /// \param dw_op_type C-style string used to vary the error output /// \param file_addr the file address we are trying to resolve and turn into a /// load address /// \param so_addr out parameter, will be set to load addresss or section offset /// \param check_sectionoffset bool which determines if having a section offset /// but not a load address is considerd a success /// \returns llvm::Optional containing the load address if resolving and getting /// the load address succeed or an empty Optinal otherwise. If /// check_sectionoffset is true we consider LLDB_INVALID_ADDRESS a /// success if so_addr.IsSectionOffset() is true. static llvm::Optional ResolveLoadAddress(ExecutionContext *exe_ctx, lldb::ModuleSP &module_sp, Status *error_ptr, const char *dw_op_type, lldb::addr_t file_addr, Address &so_addr, bool check_sectionoffset = false) { if (!module_sp) { if (error_ptr) error_ptr->SetErrorStringWithFormat( "need module to resolve file address for %s", dw_op_type); return {}; } if (!module_sp->ResolveFileAddress(file_addr, so_addr)) { if (error_ptr) error_ptr->SetErrorString("failed to resolve file address in module"); return {}; } addr_t load_addr = so_addr.GetLoadAddress(exe_ctx->GetTargetPtr()); if (load_addr == LLDB_INVALID_ADDRESS && (check_sectionoffset && !so_addr.IsSectionOffset())) { if (error_ptr) error_ptr->SetErrorString("failed to resolve load address"); return {}; } return load_addr; } /// Helper function to move common code used to load sized data from a uint8_t /// buffer. /// /// \param addr_bytes uint8_t buffer containg raw data /// \param size_addr_bytes how large is the underlying raw data /// \param byte_order what is the byter order of the underlyig data /// \param size How much of the underlying data we want to use /// \return The underlying data converted into a Scalar static Scalar DerefSizeExtractDataHelper(uint8_t *addr_bytes, size_t size_addr_bytes, ByteOrder byte_order, size_t size) { DataExtractor addr_data(addr_bytes, size_addr_bytes, byte_order, size); lldb::offset_t addr_data_offset = 0; if (size <= 8) return addr_data.GetMaxU64(&addr_data_offset, size); else return addr_data.GetAddress(&addr_data_offset); } bool DWARFExpression::Evaluate( ExecutionContext *exe_ctx, RegisterContext *reg_ctx, lldb::ModuleSP module_sp, const DataExtractor &opcodes, const DWARFUnit *dwarf_cu, const lldb::RegisterKind reg_kind, const Value *initial_value_ptr, const Value *object_address_ptr, Value &result, Status *error_ptr) { if (opcodes.GetByteSize() == 0) { if (error_ptr) error_ptr->SetErrorString( "no location, value may have been optimized out"); return false; } std::vector stack; Process *process = nullptr; StackFrame *frame = nullptr; if (exe_ctx) { process = exe_ctx->GetProcessPtr(); frame = exe_ctx->GetFramePtr(); } if (reg_ctx == nullptr && frame) reg_ctx = frame->GetRegisterContext().get(); if (initial_value_ptr) stack.push_back(*initial_value_ptr); lldb::offset_t offset = 0; Value tmp; uint32_t reg_num; /// Insertion point for evaluating multi-piece expression. uint64_t op_piece_offset = 0; Value pieces; // Used for DW_OP_piece Log *log = GetLog(LLDBLog::Expressions); // A generic type is "an integral type that has the size of an address and an // unspecified signedness". For now, just use the signedness of the operand. // TODO: Implement a real typed stack, and store the genericness of the value // there. auto to_generic = [&](auto v) { bool is_signed = std::is_signed::value; return Scalar(llvm::APSInt( llvm::APInt(8 * opcodes.GetAddressByteSize(), v, is_signed), !is_signed)); }; // The default kind is a memory location. This is updated by any // operation that changes this, such as DW_OP_stack_value, and reset // by composition operations like DW_OP_piece. LocationDescriptionKind dwarf4_location_description_kind = Memory; while (opcodes.ValidOffset(offset)) { const lldb::offset_t op_offset = offset; const uint8_t op = opcodes.GetU8(&offset); if (log && log->GetVerbose()) { size_t count = stack.size(); LLDB_LOGF(log, "Stack before operation has %" PRIu64 " values:", (uint64_t)count); for (size_t i = 0; i < count; ++i) { StreamString new_value; new_value.Printf("[%" PRIu64 "]", (uint64_t)i); stack[i].Dump(&new_value); LLDB_LOGF(log, " %s", new_value.GetData()); } LLDB_LOGF(log, "0x%8.8" PRIx64 ": %s", op_offset, DW_OP_value_to_name(op)); } switch (op) { // The DW_OP_addr operation has a single operand that encodes a machine // address and whose size is the size of an address on the target machine. case DW_OP_addr: stack.push_back(Scalar(opcodes.GetAddress(&offset))); stack.back().SetValueType(Value::ValueType::FileAddress); // Convert the file address to a load address, so subsequent // DWARF operators can operate on it. if (frame) stack.back().ConvertToLoadAddress(module_sp.get(), frame->CalculateTarget().get()); break; // The DW_OP_addr_sect_offset4 is used for any location expressions in // shared libraries that have a location like: // DW_OP_addr(0x1000) // If this address resides in a shared library, then this virtual address // won't make sense when it is evaluated in the context of a running // process where shared libraries have been slid. To account for this, this // new address type where we can store the section pointer and a 4 byte // offset. // case DW_OP_addr_sect_offset4: // { // result_type = eResultTypeFileAddress; // lldb::Section *sect = (lldb::Section // *)opcodes.GetMaxU64(&offset, sizeof(void *)); // lldb::addr_t sect_offset = opcodes.GetU32(&offset); // // Address so_addr (sect, sect_offset); // lldb::addr_t load_addr = so_addr.GetLoadAddress(); // if (load_addr != LLDB_INVALID_ADDRESS) // { // // We successfully resolve a file address to a load // // address. // stack.push_back(load_addr); // break; // } // else // { // // We were able // if (error_ptr) // error_ptr->SetErrorStringWithFormat ("Section %s in // %s is not currently loaded.\n", // sect->GetName().AsCString(), // sect->GetModule()->GetFileSpec().GetFilename().AsCString()); // return false; // } // } // break; // OPCODE: DW_OP_deref // OPERANDS: none // DESCRIPTION: Pops the top stack entry and treats it as an address. // The value retrieved from that address is pushed. The size of the data // retrieved from the dereferenced address is the size of an address on the // target machine. case DW_OP_deref: { if (stack.empty()) { if (error_ptr) error_ptr->SetErrorString("Expression stack empty for DW_OP_deref."); return false; } Value::ValueType value_type = stack.back().GetValueType(); switch (value_type) { case Value::ValueType::HostAddress: { void *src = (void *)stack.back().GetScalar().ULongLong(); intptr_t ptr; ::memcpy(&ptr, src, sizeof(void *)); stack.back().GetScalar() = ptr; stack.back().ClearContext(); } break; case Value::ValueType::FileAddress: { auto file_addr = stack.back().GetScalar().ULongLong( LLDB_INVALID_ADDRESS); Address so_addr; auto maybe_load_addr = ResolveLoadAddress( exe_ctx, module_sp, error_ptr, "DW_OP_deref", file_addr, so_addr); if (!maybe_load_addr) return false; stack.back().GetScalar() = *maybe_load_addr; // Fall through to load address promotion code below. } LLVM_FALLTHROUGH; case Value::ValueType::Scalar: // Promote Scalar to LoadAddress and fall through. stack.back().SetValueType(Value::ValueType::LoadAddress); LLVM_FALLTHROUGH; case Value::ValueType::LoadAddress: if (exe_ctx) { if (process) { lldb::addr_t pointer_addr = stack.back().GetScalar().ULongLong(LLDB_INVALID_ADDRESS); Status error; lldb::addr_t pointer_value = process->ReadPointerFromMemory(pointer_addr, error); if (pointer_value != LLDB_INVALID_ADDRESS) { if (ABISP abi_sp = process->GetABI()) pointer_value = abi_sp->FixCodeAddress(pointer_value); stack.back().GetScalar() = pointer_value; stack.back().ClearContext(); } else { if (error_ptr) error_ptr->SetErrorStringWithFormat( "Failed to dereference pointer from 0x%" PRIx64 " for DW_OP_deref: %s\n", pointer_addr, error.AsCString()); return false; } } else { if (error_ptr) error_ptr->SetErrorString("NULL process for DW_OP_deref.\n"); return false; } } else { if (error_ptr) error_ptr->SetErrorString( "NULL execution context for DW_OP_deref.\n"); return false; } break; case Value::ValueType::Invalid: if (error_ptr) error_ptr->SetErrorString("Invalid value type for DW_OP_deref.\n"); return false; } } break; // OPCODE: DW_OP_deref_size // OPERANDS: 1 // 1 - uint8_t that specifies the size of the data to dereference. // DESCRIPTION: Behaves like the DW_OP_deref operation: it pops the top // stack entry and treats it as an address. The value retrieved from that // address is pushed. In the DW_OP_deref_size operation, however, the size // in bytes of the data retrieved from the dereferenced address is // specified by the single operand. This operand is a 1-byte unsigned // integral constant whose value may not be larger than the size of an // address on the target machine. The data retrieved is zero extended to // the size of an address on the target machine before being pushed on the // expression stack. case DW_OP_deref_size: { if (stack.empty()) { if (error_ptr) error_ptr->SetErrorString( "Expression stack empty for DW_OP_deref_size."); return false; } uint8_t size = opcodes.GetU8(&offset); Value::ValueType value_type = stack.back().GetValueType(); switch (value_type) { case Value::ValueType::HostAddress: { void *src = (void *)stack.back().GetScalar().ULongLong(); intptr_t ptr; ::memcpy(&ptr, src, sizeof(void *)); // I can't decide whether the size operand should apply to the bytes in // their // lldb-host endianness or the target endianness.. I doubt this'll ever // come up but I'll opt for assuming big endian regardless. switch (size) { case 1: ptr = ptr & 0xff; break; case 2: ptr = ptr & 0xffff; break; case 3: ptr = ptr & 0xffffff; break; case 4: ptr = ptr & 0xffffffff; break; // the casts are added to work around the case where intptr_t is a 32 // bit quantity; // presumably we won't hit the 5..7 cases if (void*) is 32-bits in this // program. case 5: ptr = (intptr_t)ptr & 0xffffffffffULL; break; case 6: ptr = (intptr_t)ptr & 0xffffffffffffULL; break; case 7: ptr = (intptr_t)ptr & 0xffffffffffffffULL; break; default: break; } stack.back().GetScalar() = ptr; stack.back().ClearContext(); } break; case Value::ValueType::FileAddress: { auto file_addr = stack.back().GetScalar().ULongLong(LLDB_INVALID_ADDRESS); Address so_addr; auto maybe_load_addr = ResolveLoadAddress(exe_ctx, module_sp, error_ptr, "DW_OP_deref_size", file_addr, so_addr, /*check_sectionoffset=*/true); if (!maybe_load_addr) return false; addr_t load_addr = *maybe_load_addr; if (load_addr == LLDB_INVALID_ADDRESS && so_addr.IsSectionOffset()) { uint8_t addr_bytes[8]; Status error; if (exe_ctx->GetTargetRef().ReadMemory( so_addr, &addr_bytes, size, error, /*force_live_memory=*/false) == size) { ObjectFile *objfile = module_sp->GetObjectFile(); stack.back().GetScalar() = DerefSizeExtractDataHelper( addr_bytes, size, objfile->GetByteOrder(), size); stack.back().ClearContext(); break; } else { if (error_ptr) error_ptr->SetErrorStringWithFormat( "Failed to dereference pointer for for DW_OP_deref_size: " "%s\n", error.AsCString()); return false; } } stack.back().GetScalar() = load_addr; // Fall through to load address promotion code below. } LLVM_FALLTHROUGH; case Value::ValueType::Scalar: case Value::ValueType::LoadAddress: if (exe_ctx) { if (process) { lldb::addr_t pointer_addr = stack.back().GetScalar().ULongLong(LLDB_INVALID_ADDRESS); uint8_t addr_bytes[sizeof(lldb::addr_t)]; Status error; if (process->ReadMemory(pointer_addr, &addr_bytes, size, error) == size) { stack.back().GetScalar() = DerefSizeExtractDataHelper(addr_bytes, sizeof(addr_bytes), process->GetByteOrder(), size); stack.back().ClearContext(); } else { if (error_ptr) error_ptr->SetErrorStringWithFormat( "Failed to dereference pointer from 0x%" PRIx64 " for DW_OP_deref: %s\n", pointer_addr, error.AsCString()); return false; } } else { if (error_ptr) error_ptr->SetErrorString("NULL process for DW_OP_deref_size.\n"); return false; } } else { if (error_ptr) error_ptr->SetErrorString( "NULL execution context for DW_OP_deref_size.\n"); return false; } break; case Value::ValueType::Invalid: if (error_ptr) error_ptr->SetErrorString("Invalid value for DW_OP_deref_size.\n"); return false; } } break; // OPCODE: DW_OP_xderef_size // OPERANDS: 1 // 1 - uint8_t that specifies the size of the data to dereference. // DESCRIPTION: Behaves like the DW_OP_xderef operation: the entry at // the top of the stack is treated as an address. The second stack entry is // treated as an "address space identifier" for those architectures that // support multiple address spaces. The top two stack elements are popped, // a data item is retrieved through an implementation-defined address // calculation and pushed as the new stack top. In the DW_OP_xderef_size // operation, however, the size in bytes of the data retrieved from the // dereferenced address is specified by the single operand. This operand is // a 1-byte unsigned integral constant whose value may not be larger than // the size of an address on the target machine. The data retrieved is zero // extended to the size of an address on the target machine before being // pushed on the expression stack. case DW_OP_xderef_size: if (error_ptr) error_ptr->SetErrorString("Unimplemented opcode: DW_OP_xderef_size."); return false; // OPCODE: DW_OP_xderef // OPERANDS: none // DESCRIPTION: Provides an extended dereference mechanism. The entry at // the top of the stack is treated as an address. The second stack entry is // treated as an "address space identifier" for those architectures that // support multiple address spaces. The top two stack elements are popped, // a data item is retrieved through an implementation-defined address // calculation and pushed as the new stack top. The size of the data // retrieved from the dereferenced address is the size of an address on the // target machine. case DW_OP_xderef: if (error_ptr) error_ptr->SetErrorString("Unimplemented opcode: DW_OP_xderef."); return false; // All DW_OP_constXXX opcodes have a single operand as noted below: // // Opcode Operand 1 // DW_OP_const1u 1-byte unsigned integer constant // DW_OP_const1s 1-byte signed integer constant // DW_OP_const2u 2-byte unsigned integer constant // DW_OP_const2s 2-byte signed integer constant // DW_OP_const4u 4-byte unsigned integer constant // DW_OP_const4s 4-byte signed integer constant // DW_OP_const8u 8-byte unsigned integer constant // DW_OP_const8s 8-byte signed integer constant // DW_OP_constu unsigned LEB128 integer constant // DW_OP_consts signed LEB128 integer constant case DW_OP_const1u: stack.push_back(to_generic(opcodes.GetU8(&offset))); break; case DW_OP_const1s: stack.push_back(to_generic((int8_t)opcodes.GetU8(&offset))); break; case DW_OP_const2u: stack.push_back(to_generic(opcodes.GetU16(&offset))); break; case DW_OP_const2s: stack.push_back(to_generic((int16_t)opcodes.GetU16(&offset))); break; case DW_OP_const4u: stack.push_back(to_generic(opcodes.GetU32(&offset))); break; case DW_OP_const4s: stack.push_back(to_generic((int32_t)opcodes.GetU32(&offset))); break; case DW_OP_const8u: stack.push_back(to_generic(opcodes.GetU64(&offset))); break; case DW_OP_const8s: stack.push_back(to_generic((int64_t)opcodes.GetU64(&offset))); break; // These should also use to_generic, but we can't do that due to a // producer-side bug in llvm. See llvm.org/pr48087. case DW_OP_constu: stack.push_back(Scalar(opcodes.GetULEB128(&offset))); break; case DW_OP_consts: stack.push_back(Scalar(opcodes.GetSLEB128(&offset))); break; // OPCODE: DW_OP_dup // OPERANDS: none // DESCRIPTION: duplicates the value at the top of the stack case DW_OP_dup: if (stack.empty()) { if (error_ptr) error_ptr->SetErrorString("Expression stack empty for DW_OP_dup."); return false; } else stack.push_back(stack.back()); break; // OPCODE: DW_OP_drop // OPERANDS: none // DESCRIPTION: pops the value at the top of the stack case DW_OP_drop: if (stack.empty()) { if (error_ptr) error_ptr->SetErrorString("Expression stack empty for DW_OP_drop."); return false; } else stack.pop_back(); break; // OPCODE: DW_OP_over // OPERANDS: none // DESCRIPTION: Duplicates the entry currently second in the stack at // the top of the stack. case DW_OP_over: if (stack.size() < 2) { if (error_ptr) error_ptr->SetErrorString( "Expression stack needs at least 2 items for DW_OP_over."); return false; } else stack.push_back(stack[stack.size() - 2]); break; // OPCODE: DW_OP_pick // OPERANDS: uint8_t index into the current stack // DESCRIPTION: The stack entry with the specified index (0 through 255, // inclusive) is pushed on the stack case DW_OP_pick: { uint8_t pick_idx = opcodes.GetU8(&offset); if (pick_idx < stack.size()) stack.push_back(stack[stack.size() - 1 - pick_idx]); else { if (error_ptr) error_ptr->SetErrorStringWithFormat( "Index %u out of range for DW_OP_pick.\n", pick_idx); return false; } } break; // OPCODE: DW_OP_swap // OPERANDS: none // DESCRIPTION: swaps the top two stack entries. The entry at the top // of the stack becomes the second stack entry, and the second entry // becomes the top of the stack case DW_OP_swap: if (stack.size() < 2) { if (error_ptr) error_ptr->SetErrorString( "Expression stack needs at least 2 items for DW_OP_swap."); return false; } else { tmp = stack.back(); stack.back() = stack[stack.size() - 2]; stack[stack.size() - 2] = tmp; } break; // OPCODE: DW_OP_rot // OPERANDS: none // DESCRIPTION: Rotates the first three stack entries. The entry at // the top of the stack becomes the third stack entry, the second entry // becomes the top of the stack, and the third entry becomes the second // entry. case DW_OP_rot: if (stack.size() < 3) { if (error_ptr) error_ptr->SetErrorString( "Expression stack needs at least 3 items for DW_OP_rot."); return false; } else { size_t last_idx = stack.size() - 1; Value old_top = stack[last_idx]; stack[last_idx] = stack[last_idx - 1]; stack[last_idx - 1] = stack[last_idx - 2]; stack[last_idx - 2] = old_top; } break; // OPCODE: DW_OP_abs // OPERANDS: none // DESCRIPTION: pops the top stack entry, interprets it as a signed // value and pushes its absolute value. If the absolute value can not be // represented, the result is undefined. case DW_OP_abs: if (stack.empty()) { if (error_ptr) error_ptr->SetErrorString( "Expression stack needs at least 1 item for DW_OP_abs."); return false; } else if (!stack.back().ResolveValue(exe_ctx).AbsoluteValue()) { if (error_ptr) error_ptr->SetErrorString( "Failed to take the absolute value of the first stack item."); return false; } break; // OPCODE: DW_OP_and // OPERANDS: none // DESCRIPTION: pops the top two stack values, performs a bitwise and // operation on the two, and pushes the result. case DW_OP_and: if (stack.size() < 2) { if (error_ptr) error_ptr->SetErrorString( "Expression stack needs at least 2 items for DW_OP_and."); return false; } else { tmp = stack.back(); stack.pop_back(); stack.back().ResolveValue(exe_ctx) = stack.back().ResolveValue(exe_ctx) & tmp.ResolveValue(exe_ctx); } break; // OPCODE: DW_OP_div // OPERANDS: none // DESCRIPTION: pops the top two stack values, divides the former second // entry by the former top of the stack using signed division, and pushes // the result. case DW_OP_div: if (stack.size() < 2) { if (error_ptr) error_ptr->SetErrorString( "Expression stack needs at least 2 items for DW_OP_div."); return false; } else { tmp = stack.back(); if (tmp.ResolveValue(exe_ctx).IsZero()) { if (error_ptr) error_ptr->SetErrorString("Divide by zero."); return false; } else { stack.pop_back(); stack.back() = stack.back().ResolveValue(exe_ctx) / tmp.ResolveValue(exe_ctx); if (!stack.back().ResolveValue(exe_ctx).IsValid()) { if (error_ptr) error_ptr->SetErrorString("Divide failed."); return false; } } } break; // OPCODE: DW_OP_minus // OPERANDS: none // DESCRIPTION: pops the top two stack values, subtracts the former top // of the stack from the former second entry, and pushes the result. case DW_OP_minus: if (stack.size() < 2) { if (error_ptr) error_ptr->SetErrorString( "Expression stack needs at least 2 items for DW_OP_minus."); return false; } else { tmp = stack.back(); stack.pop_back(); stack.back().ResolveValue(exe_ctx) = stack.back().ResolveValue(exe_ctx) - tmp.ResolveValue(exe_ctx); } break; // OPCODE: DW_OP_mod // OPERANDS: none // DESCRIPTION: pops the top two stack values and pushes the result of // the calculation: former second stack entry modulo the former top of the // stack. case DW_OP_mod: if (stack.size() < 2) { if (error_ptr) error_ptr->SetErrorString( "Expression stack needs at least 2 items for DW_OP_mod."); return false; } else { tmp = stack.back(); stack.pop_back(); stack.back().ResolveValue(exe_ctx) = stack.back().ResolveValue(exe_ctx) % tmp.ResolveValue(exe_ctx); } break; // OPCODE: DW_OP_mul // OPERANDS: none // DESCRIPTION: pops the top two stack entries, multiplies them // together, and pushes the result. case DW_OP_mul: if (stack.size() < 2) { if (error_ptr) error_ptr->SetErrorString( "Expression stack needs at least 2 items for DW_OP_mul."); return false; } else { tmp = stack.back(); stack.pop_back(); stack.back().ResolveValue(exe_ctx) = stack.back().ResolveValue(exe_ctx) * tmp.ResolveValue(exe_ctx); } break; // OPCODE: DW_OP_neg // OPERANDS: none // DESCRIPTION: pops the top stack entry, and pushes its negation. case DW_OP_neg: if (stack.empty()) { if (error_ptr) error_ptr->SetErrorString( "Expression stack needs at least 1 item for DW_OP_neg."); return false; } else { if (!stack.back().ResolveValue(exe_ctx).UnaryNegate()) { if (error_ptr) error_ptr->SetErrorString("Unary negate failed."); return false; } } break; // OPCODE: DW_OP_not // OPERANDS: none // DESCRIPTION: pops the top stack entry, and pushes its bitwise // complement case DW_OP_not: if (stack.empty()) { if (error_ptr) error_ptr->SetErrorString( "Expression stack needs at least 1 item for DW_OP_not."); return false; } else { if (!stack.back().ResolveValue(exe_ctx).OnesComplement()) { if (error_ptr) error_ptr->SetErrorString("Logical NOT failed."); return false; } } break; // OPCODE: DW_OP_or // OPERANDS: none // DESCRIPTION: pops the top two stack entries, performs a bitwise or // operation on the two, and pushes the result. case DW_OP_or: if (stack.size() < 2) { if (error_ptr) error_ptr->SetErrorString( "Expression stack needs at least 2 items for DW_OP_or."); return false; } else { tmp = stack.back(); stack.pop_back(); stack.back().ResolveValue(exe_ctx) = stack.back().ResolveValue(exe_ctx) | tmp.ResolveValue(exe_ctx); } break; // OPCODE: DW_OP_plus // OPERANDS: none // DESCRIPTION: pops the top two stack entries, adds them together, and // pushes the result. case DW_OP_plus: if (stack.size() < 2) { if (error_ptr) error_ptr->SetErrorString( "Expression stack needs at least 2 items for DW_OP_plus."); return false; } else { tmp = stack.back(); stack.pop_back(); stack.back().GetScalar() += tmp.GetScalar(); } break; // OPCODE: DW_OP_plus_uconst // OPERANDS: none // DESCRIPTION: pops the top stack entry, adds it to the unsigned LEB128 // constant operand and pushes the result. case DW_OP_plus_uconst: if (stack.empty()) { if (error_ptr) error_ptr->SetErrorString( "Expression stack needs at least 1 item for DW_OP_plus_uconst."); return false; } else { const uint64_t uconst_value = opcodes.GetULEB128(&offset); // Implicit conversion from a UINT to a Scalar... stack.back().GetScalar() += uconst_value; if (!stack.back().GetScalar().IsValid()) { if (error_ptr) error_ptr->SetErrorString("DW_OP_plus_uconst failed."); return false; } } break; // OPCODE: DW_OP_shl // OPERANDS: none // DESCRIPTION: pops the top two stack entries, shifts the former // second entry left by the number of bits specified by the former top of // the stack, and pushes the result. case DW_OP_shl: if (stack.size() < 2) { if (error_ptr) error_ptr->SetErrorString( "Expression stack needs at least 2 items for DW_OP_shl."); return false; } else { tmp = stack.back(); stack.pop_back(); stack.back().ResolveValue(exe_ctx) <<= tmp.ResolveValue(exe_ctx); } break; // OPCODE: DW_OP_shr // OPERANDS: none // DESCRIPTION: pops the top two stack entries, shifts the former second // entry right logically (filling with zero bits) by the number of bits // specified by the former top of the stack, and pushes the result. case DW_OP_shr: if (stack.size() < 2) { if (error_ptr) error_ptr->SetErrorString( "Expression stack needs at least 2 items for DW_OP_shr."); return false; } else { tmp = stack.back(); stack.pop_back(); if (!stack.back().ResolveValue(exe_ctx).ShiftRightLogical( tmp.ResolveValue(exe_ctx))) { if (error_ptr) error_ptr->SetErrorString("DW_OP_shr failed."); return false; } } break; // OPCODE: DW_OP_shra // OPERANDS: none // DESCRIPTION: pops the top two stack entries, shifts the former second // entry right arithmetically (divide the magnitude by 2, keep the same // sign for the result) by the number of bits specified by the former top // of the stack, and pushes the result. case DW_OP_shra: if (stack.size() < 2) { if (error_ptr) error_ptr->SetErrorString( "Expression stack needs at least 2 items for DW_OP_shra."); return false; } else { tmp = stack.back(); stack.pop_back(); stack.back().ResolveValue(exe_ctx) >>= tmp.ResolveValue(exe_ctx); } break; // OPCODE: DW_OP_xor // OPERANDS: none // DESCRIPTION: pops the top two stack entries, performs the bitwise // exclusive-or operation on the two, and pushes the result. case DW_OP_xor: if (stack.size() < 2) { if (error_ptr) error_ptr->SetErrorString( "Expression stack needs at least 2 items for DW_OP_xor."); return false; } else { tmp = stack.back(); stack.pop_back(); stack.back().ResolveValue(exe_ctx) = stack.back().ResolveValue(exe_ctx) ^ tmp.ResolveValue(exe_ctx); } break; // OPCODE: DW_OP_skip // OPERANDS: int16_t // DESCRIPTION: An unconditional branch. Its single operand is a 2-byte // signed integer constant. The 2-byte constant is the number of bytes of // the DWARF expression to skip forward or backward from the current // operation, beginning after the 2-byte constant. case DW_OP_skip: { int16_t skip_offset = (int16_t)opcodes.GetU16(&offset); lldb::offset_t new_offset = offset + skip_offset; if (opcodes.ValidOffset(new_offset)) offset = new_offset; else { if (error_ptr) error_ptr->SetErrorString("Invalid opcode offset in DW_OP_skip."); return false; } } break; // OPCODE: DW_OP_bra // OPERANDS: int16_t // DESCRIPTION: A conditional branch. Its single operand is a 2-byte // signed integer constant. This operation pops the top of stack. If the // value popped is not the constant 0, the 2-byte constant operand is the // number of bytes of the DWARF expression to skip forward or backward from // the current operation, beginning after the 2-byte constant. case DW_OP_bra: if (stack.empty()) { if (error_ptr) error_ptr->SetErrorString( "Expression stack needs at least 1 item for DW_OP_bra."); return false; } else { tmp = stack.back(); stack.pop_back(); int16_t bra_offset = (int16_t)opcodes.GetU16(&offset); Scalar zero(0); if (tmp.ResolveValue(exe_ctx) != zero) { lldb::offset_t new_offset = offset + bra_offset; if (opcodes.ValidOffset(new_offset)) offset = new_offset; else { if (error_ptr) error_ptr->SetErrorString("Invalid opcode offset in DW_OP_bra."); return false; } } } break; // OPCODE: DW_OP_eq // OPERANDS: none // DESCRIPTION: pops the top two stack values, compares using the // equals (==) operator. // STACK RESULT: push the constant value 1 onto the stack if the result // of the operation is true or the constant value 0 if the result of the // operation is false. case DW_OP_eq: if (stack.size() < 2) { if (error_ptr) error_ptr->SetErrorString( "Expression stack needs at least 2 items for DW_OP_eq."); return false; } else { tmp = stack.back(); stack.pop_back(); stack.back().ResolveValue(exe_ctx) = stack.back().ResolveValue(exe_ctx) == tmp.ResolveValue(exe_ctx); } break; // OPCODE: DW_OP_ge // OPERANDS: none // DESCRIPTION: pops the top two stack values, compares using the // greater than or equal to (>=) operator. // STACK RESULT: push the constant value 1 onto the stack if the result // of the operation is true or the constant value 0 if the result of the // operation is false. case DW_OP_ge: if (stack.size() < 2) { if (error_ptr) error_ptr->SetErrorString( "Expression stack needs at least 2 items for DW_OP_ge."); return false; } else { tmp = stack.back(); stack.pop_back(); stack.back().ResolveValue(exe_ctx) = stack.back().ResolveValue(exe_ctx) >= tmp.ResolveValue(exe_ctx); } break; // OPCODE: DW_OP_gt // OPERANDS: none // DESCRIPTION: pops the top two stack values, compares using the // greater than (>) operator. // STACK RESULT: push the constant value 1 onto the stack if the result // of the operation is true or the constant value 0 if the result of the // operation is false. case DW_OP_gt: if (stack.size() < 2) { if (error_ptr) error_ptr->SetErrorString( "Expression stack needs at least 2 items for DW_OP_gt."); return false; } else { tmp = stack.back(); stack.pop_back(); stack.back().ResolveValue(exe_ctx) = stack.back().ResolveValue(exe_ctx) > tmp.ResolveValue(exe_ctx); } break; // OPCODE: DW_OP_le // OPERANDS: none // DESCRIPTION: pops the top two stack values, compares using the // less than or equal to (<=) operator. // STACK RESULT: push the constant value 1 onto the stack if the result // of the operation is true or the constant value 0 if the result of the // operation is false. case DW_OP_le: if (stack.size() < 2) { if (error_ptr) error_ptr->SetErrorString( "Expression stack needs at least 2 items for DW_OP_le."); return false; } else { tmp = stack.back(); stack.pop_back(); stack.back().ResolveValue(exe_ctx) = stack.back().ResolveValue(exe_ctx) <= tmp.ResolveValue(exe_ctx); } break; // OPCODE: DW_OP_lt // OPERANDS: none // DESCRIPTION: pops the top two stack values, compares using the // less than (<) operator. // STACK RESULT: push the constant value 1 onto the stack if the result // of the operation is true or the constant value 0 if the result of the // operation is false. case DW_OP_lt: if (stack.size() < 2) { if (error_ptr) error_ptr->SetErrorString( "Expression stack needs at least 2 items for DW_OP_lt."); return false; } else { tmp = stack.back(); stack.pop_back(); stack.back().ResolveValue(exe_ctx) = stack.back().ResolveValue(exe_ctx) < tmp.ResolveValue(exe_ctx); } break; // OPCODE: DW_OP_ne // OPERANDS: none // DESCRIPTION: pops the top two stack values, compares using the // not equal (!=) operator. // STACK RESULT: push the constant value 1 onto the stack if the result // of the operation is true or the constant value 0 if the result of the // operation is false. case DW_OP_ne: if (stack.size() < 2) { if (error_ptr) error_ptr->SetErrorString( "Expression stack needs at least 2 items for DW_OP_ne."); return false; } else { tmp = stack.back(); stack.pop_back(); stack.back().ResolveValue(exe_ctx) = stack.back().ResolveValue(exe_ctx) != tmp.ResolveValue(exe_ctx); } break; // OPCODE: DW_OP_litn // OPERANDS: none // DESCRIPTION: encode the unsigned literal values from 0 through 31. // STACK RESULT: push the unsigned literal constant value onto the top // of the stack. case DW_OP_lit0: case DW_OP_lit1: case DW_OP_lit2: case DW_OP_lit3: case DW_OP_lit4: case DW_OP_lit5: case DW_OP_lit6: case DW_OP_lit7: case DW_OP_lit8: case DW_OP_lit9: case DW_OP_lit10: case DW_OP_lit11: case DW_OP_lit12: case DW_OP_lit13: case DW_OP_lit14: case DW_OP_lit15: case DW_OP_lit16: case DW_OP_lit17: case DW_OP_lit18: case DW_OP_lit19: case DW_OP_lit20: case DW_OP_lit21: case DW_OP_lit22: case DW_OP_lit23: case DW_OP_lit24: case DW_OP_lit25: case DW_OP_lit26: case DW_OP_lit27: case DW_OP_lit28: case DW_OP_lit29: case DW_OP_lit30: case DW_OP_lit31: stack.push_back(to_generic(op - DW_OP_lit0)); break; // OPCODE: DW_OP_regN // OPERANDS: none // DESCRIPTION: Push the value in register n on the top of the stack. case DW_OP_reg0: case DW_OP_reg1: case DW_OP_reg2: case DW_OP_reg3: case DW_OP_reg4: case DW_OP_reg5: case DW_OP_reg6: case DW_OP_reg7: case DW_OP_reg8: case DW_OP_reg9: case DW_OP_reg10: case DW_OP_reg11: case DW_OP_reg12: case DW_OP_reg13: case DW_OP_reg14: case DW_OP_reg15: case DW_OP_reg16: case DW_OP_reg17: case DW_OP_reg18: case DW_OP_reg19: case DW_OP_reg20: case DW_OP_reg21: case DW_OP_reg22: case DW_OP_reg23: case DW_OP_reg24: case DW_OP_reg25: case DW_OP_reg26: case DW_OP_reg27: case DW_OP_reg28: case DW_OP_reg29: case DW_OP_reg30: case DW_OP_reg31: { dwarf4_location_description_kind = Register; reg_num = op - DW_OP_reg0; if (ReadRegisterValueAsScalar(reg_ctx, reg_kind, reg_num, error_ptr, tmp)) stack.push_back(tmp); else return false; } break; // OPCODE: DW_OP_regx // OPERANDS: // ULEB128 literal operand that encodes the register. // DESCRIPTION: Push the value in register on the top of the stack. case DW_OP_regx: { dwarf4_location_description_kind = Register; reg_num = opcodes.GetULEB128(&offset); if (ReadRegisterValueAsScalar(reg_ctx, reg_kind, reg_num, error_ptr, tmp)) stack.push_back(tmp); else return false; } break; // OPCODE: DW_OP_bregN // OPERANDS: // SLEB128 offset from register N // DESCRIPTION: Value is in memory at the address specified by register // N plus an offset. case DW_OP_breg0: case DW_OP_breg1: case DW_OP_breg2: case DW_OP_breg3: case DW_OP_breg4: case DW_OP_breg5: case DW_OP_breg6: case DW_OP_breg7: case DW_OP_breg8: case DW_OP_breg9: case DW_OP_breg10: case DW_OP_breg11: case DW_OP_breg12: case DW_OP_breg13: case DW_OP_breg14: case DW_OP_breg15: case DW_OP_breg16: case DW_OP_breg17: case DW_OP_breg18: case DW_OP_breg19: case DW_OP_breg20: case DW_OP_breg21: case DW_OP_breg22: case DW_OP_breg23: case DW_OP_breg24: case DW_OP_breg25: case DW_OP_breg26: case DW_OP_breg27: case DW_OP_breg28: case DW_OP_breg29: case DW_OP_breg30: case DW_OP_breg31: { reg_num = op - DW_OP_breg0; if (ReadRegisterValueAsScalar(reg_ctx, reg_kind, reg_num, error_ptr, tmp)) { int64_t breg_offset = opcodes.GetSLEB128(&offset); tmp.ResolveValue(exe_ctx) += (uint64_t)breg_offset; tmp.ClearContext(); stack.push_back(tmp); stack.back().SetValueType(Value::ValueType::LoadAddress); } else return false; } break; // OPCODE: DW_OP_bregx // OPERANDS: 2 // ULEB128 literal operand that encodes the register. // SLEB128 offset from register N // DESCRIPTION: Value is in memory at the address specified by register // N plus an offset. case DW_OP_bregx: { reg_num = opcodes.GetULEB128(&offset); if (ReadRegisterValueAsScalar(reg_ctx, reg_kind, reg_num, error_ptr, tmp)) { int64_t breg_offset = opcodes.GetSLEB128(&offset); tmp.ResolveValue(exe_ctx) += (uint64_t)breg_offset; tmp.ClearContext(); stack.push_back(tmp); stack.back().SetValueType(Value::ValueType::LoadAddress); } else return false; } break; case DW_OP_fbreg: if (exe_ctx) { if (frame) { Scalar value; if (frame->GetFrameBaseValue(value, error_ptr)) { int64_t fbreg_offset = opcodes.GetSLEB128(&offset); value += fbreg_offset; stack.push_back(value); stack.back().SetValueType(Value::ValueType::LoadAddress); } else return false; } else { if (error_ptr) error_ptr->SetErrorString( "Invalid stack frame in context for DW_OP_fbreg opcode."); return false; } } else { if (error_ptr) error_ptr->SetErrorString( "NULL execution context for DW_OP_fbreg.\n"); return false; } break; // OPCODE: DW_OP_nop // OPERANDS: none // DESCRIPTION: A place holder. It has no effect on the location stack // or any of its values. case DW_OP_nop: break; // OPCODE: DW_OP_piece // OPERANDS: 1 // ULEB128: byte size of the piece // DESCRIPTION: The operand describes the size in bytes of the piece of // the object referenced by the DWARF expression whose result is at the top // of the stack. If the piece is located in a register, but does not occupy // the entire register, the placement of the piece within that register is // defined by the ABI. // // Many compilers store a single variable in sets of registers, or store a // variable partially in memory and partially in registers. DW_OP_piece // provides a way of describing how large a part of a variable a particular // DWARF expression refers to. case DW_OP_piece: { LocationDescriptionKind piece_locdesc = dwarf4_location_description_kind; // Reset for the next piece. dwarf4_location_description_kind = Memory; const uint64_t piece_byte_size = opcodes.GetULEB128(&offset); if (piece_byte_size > 0) { Value curr_piece; if (stack.empty()) { UpdateValueTypeFromLocationDescription( log, dwarf_cu, LocationDescriptionKind::Empty); // In a multi-piece expression, this means that the current piece is // not available. Fill with zeros for now by resizing the data and // appending it curr_piece.ResizeData(piece_byte_size); // Note that "0" is not a correct value for the unknown bits. // It would be better to also return a mask of valid bits together // with the expression result, so the debugger can print missing // members as "" or something. ::memset(curr_piece.GetBuffer().GetBytes(), 0, piece_byte_size); pieces.AppendDataToHostBuffer(curr_piece); } else { Status error; // Extract the current piece into "curr_piece" Value curr_piece_source_value(stack.back()); stack.pop_back(); UpdateValueTypeFromLocationDescription(log, dwarf_cu, piece_locdesc, &curr_piece_source_value); const Value::ValueType curr_piece_source_value_type = curr_piece_source_value.GetValueType(); switch (curr_piece_source_value_type) { case Value::ValueType::Invalid: return false; case Value::ValueType::LoadAddress: if (process) { if (curr_piece.ResizeData(piece_byte_size) == piece_byte_size) { lldb::addr_t load_addr = curr_piece_source_value.GetScalar().ULongLong( LLDB_INVALID_ADDRESS); if (process->ReadMemory( load_addr, curr_piece.GetBuffer().GetBytes(), piece_byte_size, error) != piece_byte_size) { if (error_ptr) error_ptr->SetErrorStringWithFormat( "failed to read memory DW_OP_piece(%" PRIu64 ") from 0x%" PRIx64, piece_byte_size, load_addr); return false; } } else { if (error_ptr) error_ptr->SetErrorStringWithFormat( "failed to resize the piece memory buffer for " "DW_OP_piece(%" PRIu64 ")", piece_byte_size); return false; } } break; case Value::ValueType::FileAddress: case Value::ValueType::HostAddress: if (error_ptr) { lldb::addr_t addr = curr_piece_source_value.GetScalar().ULongLong( LLDB_INVALID_ADDRESS); error_ptr->SetErrorStringWithFormat( "failed to read memory DW_OP_piece(%" PRIu64 ") from %s address 0x%" PRIx64, piece_byte_size, curr_piece_source_value.GetValueType() == Value::ValueType::FileAddress ? "file" : "host", addr); } return false; case Value::ValueType::Scalar: { uint32_t bit_size = piece_byte_size * 8; uint32_t bit_offset = 0; Scalar &scalar = curr_piece_source_value.GetScalar(); if (!scalar.ExtractBitfield( bit_size, bit_offset)) { if (error_ptr) error_ptr->SetErrorStringWithFormat( "unable to extract %" PRIu64 " bytes from a %" PRIu64 " byte scalar value.", piece_byte_size, (uint64_t)curr_piece_source_value.GetScalar() .GetByteSize()); return false; } // Create curr_piece with bit_size. By default Scalar // grows to the nearest host integer type. llvm::APInt fail_value(1, 0, false); llvm::APInt ap_int = scalar.UInt128(fail_value); assert(ap_int.getBitWidth() >= bit_size); llvm::ArrayRef buf{ap_int.getRawData(), ap_int.getNumWords()}; curr_piece.GetScalar() = Scalar(llvm::APInt(bit_size, buf)); } break; } // Check if this is the first piece? if (op_piece_offset == 0) { // This is the first piece, we should push it back onto the stack // so subsequent pieces will be able to access this piece and add // to it. if (pieces.AppendDataToHostBuffer(curr_piece) == 0) { if (error_ptr) error_ptr->SetErrorString("failed to append piece data"); return false; } } else { // If this is the second or later piece there should be a value on // the stack. if (pieces.GetBuffer().GetByteSize() != op_piece_offset) { if (error_ptr) error_ptr->SetErrorStringWithFormat( "DW_OP_piece for offset %" PRIu64 " but top of stack is of size %" PRIu64, op_piece_offset, pieces.GetBuffer().GetByteSize()); return false; } if (pieces.AppendDataToHostBuffer(curr_piece) == 0) { if (error_ptr) error_ptr->SetErrorString("failed to append piece data"); return false; } } } op_piece_offset += piece_byte_size; } } break; case DW_OP_bit_piece: // 0x9d ULEB128 bit size, ULEB128 bit offset (DWARF3); if (stack.size() < 1) { UpdateValueTypeFromLocationDescription(log, dwarf_cu, LocationDescriptionKind::Empty); // Reset for the next piece. dwarf4_location_description_kind = Memory; if (error_ptr) error_ptr->SetErrorString( "Expression stack needs at least 1 item for DW_OP_bit_piece."); return false; } else { UpdateValueTypeFromLocationDescription( log, dwarf_cu, dwarf4_location_description_kind, &stack.back()); // Reset for the next piece. dwarf4_location_description_kind = Memory; const uint64_t piece_bit_size = opcodes.GetULEB128(&offset); const uint64_t piece_bit_offset = opcodes.GetULEB128(&offset); switch (stack.back().GetValueType()) { case Value::ValueType::Invalid: return false; case Value::ValueType::Scalar: { if (!stack.back().GetScalar().ExtractBitfield(piece_bit_size, piece_bit_offset)) { if (error_ptr) error_ptr->SetErrorStringWithFormat( "unable to extract %" PRIu64 " bit value with %" PRIu64 " bit offset from a %" PRIu64 " bit scalar value.", piece_bit_size, piece_bit_offset, (uint64_t)(stack.back().GetScalar().GetByteSize() * 8)); return false; } } break; case Value::ValueType::FileAddress: case Value::ValueType::LoadAddress: case Value::ValueType::HostAddress: if (error_ptr) { error_ptr->SetErrorStringWithFormat( "unable to extract DW_OP_bit_piece(bit_size = %" PRIu64 ", bit_offset = %" PRIu64 ") from an address value.", piece_bit_size, piece_bit_offset); } return false; } } break; // OPCODE: DW_OP_implicit_value // OPERANDS: 2 // ULEB128 size of the value block in bytes // uint8_t* block bytes encoding value in target's memory // representation // DESCRIPTION: Value is immediately stored in block in the debug info with // the memory representation of the target. case DW_OP_implicit_value: { dwarf4_location_description_kind = Implicit; const uint32_t len = opcodes.GetULEB128(&offset); const void *data = opcodes.GetData(&offset, len); if (!data) { LLDB_LOG(log, "Evaluate_DW_OP_implicit_value: could not be read data"); LLDB_ERRORF(error_ptr, "Could not evaluate %s.", DW_OP_value_to_name(op)); return false; } Value result(data, len); stack.push_back(result); break; } case DW_OP_implicit_pointer: { dwarf4_location_description_kind = Implicit; LLDB_ERRORF(error_ptr, "Could not evaluate %s.", DW_OP_value_to_name(op)); return false; } // OPCODE: DW_OP_push_object_address // OPERANDS: none // DESCRIPTION: Pushes the address of the object currently being // evaluated as part of evaluation of a user presented expression. This // object may correspond to an independent variable described by its own // DIE or it may be a component of an array, structure, or class whose // address has been dynamically determined by an earlier step during user // expression evaluation. case DW_OP_push_object_address: if (object_address_ptr) stack.push_back(*object_address_ptr); else { if (error_ptr) error_ptr->SetErrorString("DW_OP_push_object_address used without " "specifying an object address"); return false; } break; // OPCODE: DW_OP_call2 // OPERANDS: // uint16_t compile unit relative offset of a DIE // DESCRIPTION: Performs subroutine calls during evaluation // of a DWARF expression. The operand is the 2-byte unsigned offset of a // debugging information entry in the current compilation unit. // // Operand interpretation is exactly like that for DW_FORM_ref2. // // This operation transfers control of DWARF expression evaluation to the // DW_AT_location attribute of the referenced DIE. If there is no such // attribute, then there is no effect. Execution of the DWARF expression of // a DW_AT_location attribute may add to and/or remove from values on the // stack. Execution returns to the point following the call when the end of // the attribute is reached. Values on the stack at the time of the call // may be used as parameters by the called expression and values left on // the stack by the called expression may be used as return values by prior // agreement between the calling and called expressions. case DW_OP_call2: if (error_ptr) error_ptr->SetErrorString("Unimplemented opcode DW_OP_call2."); return false; // OPCODE: DW_OP_call4 // OPERANDS: 1 // uint32_t compile unit relative offset of a DIE // DESCRIPTION: Performs a subroutine call during evaluation of a DWARF // expression. For DW_OP_call4, the operand is a 4-byte unsigned offset of // a debugging information entry in the current compilation unit. // // Operand interpretation DW_OP_call4 is exactly like that for // DW_FORM_ref4. // // This operation transfers control of DWARF expression evaluation to the // DW_AT_location attribute of the referenced DIE. If there is no such // attribute, then there is no effect. Execution of the DWARF expression of // a DW_AT_location attribute may add to and/or remove from values on the // stack. Execution returns to the point following the call when the end of // the attribute is reached. Values on the stack at the time of the call // may be used as parameters by the called expression and values left on // the stack by the called expression may be used as return values by prior // agreement between the calling and called expressions. case DW_OP_call4: if (error_ptr) error_ptr->SetErrorString("Unimplemented opcode DW_OP_call4."); return false; // OPCODE: DW_OP_stack_value // OPERANDS: None // DESCRIPTION: Specifies that the object does not exist in memory but // rather is a constant value. The value from the top of the stack is the // value to be used. This is the actual object value and not the location. case DW_OP_stack_value: dwarf4_location_description_kind = Implicit; if (stack.empty()) { if (error_ptr) error_ptr->SetErrorString( "Expression stack needs at least 1 item for DW_OP_stack_value."); return false; } stack.back().SetValueType(Value::ValueType::Scalar); break; // OPCODE: DW_OP_convert // OPERANDS: 1 // A ULEB128 that is either a DIE offset of a // DW_TAG_base_type or 0 for the generic (pointer-sized) type. // // DESCRIPTION: Pop the top stack element, convert it to a // different type, and push the result. case DW_OP_convert: { if (stack.size() < 1) { if (error_ptr) error_ptr->SetErrorString( "Expression stack needs at least 1 item for DW_OP_convert."); return false; } const uint64_t die_offset = opcodes.GetULEB128(&offset); uint64_t bit_size; bool sign; if (die_offset == 0) { // The generic type has the size of an address on the target // machine and an unspecified signedness. Scalar has no // "unspecified signedness", so we use unsigned types. if (!module_sp) { if (error_ptr) error_ptr->SetErrorString("No module"); return false; } sign = false; bit_size = module_sp->GetArchitecture().GetAddressByteSize() * 8; if (!bit_size) { if (error_ptr) error_ptr->SetErrorString("unspecified architecture"); return false; } } else { // Retrieve the type DIE that the value is being converted to. // FIXME: the constness has annoying ripple effects. DWARFDIE die = const_cast(dwarf_cu)->GetDIE(die_offset); if (!die) { if (error_ptr) error_ptr->SetErrorString("Cannot resolve DW_OP_convert type DIE"); return false; } uint64_t encoding = die.GetAttributeValueAsUnsigned(DW_AT_encoding, DW_ATE_hi_user); bit_size = die.GetAttributeValueAsUnsigned(DW_AT_byte_size, 0) * 8; if (!bit_size) bit_size = die.GetAttributeValueAsUnsigned(DW_AT_bit_size, 0); if (!bit_size) { if (error_ptr) error_ptr->SetErrorString("Unsupported type size in DW_OP_convert"); return false; } switch (encoding) { case DW_ATE_signed: case DW_ATE_signed_char: sign = true; break; case DW_ATE_unsigned: case DW_ATE_unsigned_char: sign = false; break; default: if (error_ptr) error_ptr->SetErrorString("Unsupported encoding in DW_OP_convert"); return false; } } Scalar &top = stack.back().ResolveValue(exe_ctx); top.TruncOrExtendTo(bit_size, sign); break; } // OPCODE: DW_OP_call_frame_cfa // OPERANDS: None // DESCRIPTION: Specifies a DWARF expression that pushes the value of // the canonical frame address consistent with the call frame information // located in .debug_frame (or in the FDEs of the eh_frame section). case DW_OP_call_frame_cfa: if (frame) { // Note that we don't have to parse FDEs because this DWARF expression // is commonly evaluated with a valid stack frame. StackID id = frame->GetStackID(); addr_t cfa = id.GetCallFrameAddress(); if (cfa != LLDB_INVALID_ADDRESS) { stack.push_back(Scalar(cfa)); stack.back().SetValueType(Value::ValueType::LoadAddress); } else if (error_ptr) error_ptr->SetErrorString("Stack frame does not include a canonical " "frame address for DW_OP_call_frame_cfa " "opcode."); } else { if (error_ptr) error_ptr->SetErrorString("Invalid stack frame in context for " "DW_OP_call_frame_cfa opcode."); return false; } break; // OPCODE: DW_OP_form_tls_address (or the old pre-DWARFv3 vendor extension // opcode, DW_OP_GNU_push_tls_address) // OPERANDS: none // DESCRIPTION: Pops a TLS offset from the stack, converts it to // an address in the current thread's thread-local storage block, and // pushes it on the stack. case DW_OP_form_tls_address: case DW_OP_GNU_push_tls_address: { if (stack.size() < 1) { if (error_ptr) { if (op == DW_OP_form_tls_address) error_ptr->SetErrorString( "DW_OP_form_tls_address needs an argument."); else error_ptr->SetErrorString( "DW_OP_GNU_push_tls_address needs an argument."); } return false; } if (!exe_ctx || !module_sp) { if (error_ptr) error_ptr->SetErrorString("No context to evaluate TLS within."); return false; } Thread *thread = exe_ctx->GetThreadPtr(); if (!thread) { if (error_ptr) error_ptr->SetErrorString("No thread to evaluate TLS within."); return false; } // Lookup the TLS block address for this thread and module. const addr_t tls_file_addr = stack.back().GetScalar().ULongLong(LLDB_INVALID_ADDRESS); const addr_t tls_load_addr = thread->GetThreadLocalData(module_sp, tls_file_addr); if (tls_load_addr == LLDB_INVALID_ADDRESS) { if (error_ptr) error_ptr->SetErrorString( "No TLS data currently exists for this thread."); return false; } stack.back().GetScalar() = tls_load_addr; stack.back().SetValueType(Value::ValueType::LoadAddress); } break; // OPCODE: DW_OP_addrx (DW_OP_GNU_addr_index is the legacy name.) // OPERANDS: 1 // ULEB128: index to the .debug_addr section // DESCRIPTION: Pushes an address to the stack from the .debug_addr // section with the base address specified by the DW_AT_addr_base attribute // and the 0 based index is the ULEB128 encoded index. case DW_OP_addrx: case DW_OP_GNU_addr_index: { if (!dwarf_cu) { if (error_ptr) error_ptr->SetErrorString("DW_OP_GNU_addr_index found without a " "compile unit being specified"); return false; } uint64_t index = opcodes.GetULEB128(&offset); lldb::addr_t value = dwarf_cu->ReadAddressFromDebugAddrSection(index); stack.push_back(Scalar(value)); stack.back().SetValueType(Value::ValueType::FileAddress); } break; // OPCODE: DW_OP_GNU_const_index // OPERANDS: 1 // ULEB128: index to the .debug_addr section // DESCRIPTION: Pushes an constant with the size of a machine address to // the stack from the .debug_addr section with the base address specified // by the DW_AT_addr_base attribute and the 0 based index is the ULEB128 // encoded index. case DW_OP_GNU_const_index: { if (!dwarf_cu) { if (error_ptr) error_ptr->SetErrorString("DW_OP_GNU_const_index found without a " "compile unit being specified"); return false; } uint64_t index = opcodes.GetULEB128(&offset); lldb::addr_t value = dwarf_cu->ReadAddressFromDebugAddrSection(index); stack.push_back(Scalar(value)); } break; case DW_OP_GNU_entry_value: case DW_OP_entry_value: { if (!Evaluate_DW_OP_entry_value(stack, exe_ctx, reg_ctx, opcodes, offset, error_ptr, log)) { LLDB_ERRORF(error_ptr, "Could not evaluate %s.", DW_OP_value_to_name(op)); return false; } break; } default: if (error_ptr) error_ptr->SetErrorStringWithFormatv( "Unhandled opcode {0} in DWARFExpression", LocationAtom(op)); return false; } } if (stack.empty()) { // Nothing on the stack, check if we created a piece value from DW_OP_piece // or DW_OP_bit_piece opcodes if (pieces.GetBuffer().GetByteSize()) { result = pieces; return true; } if (error_ptr) error_ptr->SetErrorString("Stack empty after evaluation."); return false; } UpdateValueTypeFromLocationDescription( log, dwarf_cu, dwarf4_location_description_kind, &stack.back()); if (log && log->GetVerbose()) { size_t count = stack.size(); LLDB_LOGF(log, "Stack after operation has %" PRIu64 " values:", (uint64_t)count); for (size_t i = 0; i < count; ++i) { StreamString new_value; new_value.Printf("[%" PRIu64 "]", (uint64_t)i); stack[i].Dump(&new_value); LLDB_LOGF(log, " %s", new_value.GetData()); } } result = stack.back(); return true; // Return true on success } bool DWARFExpression::ParseDWARFLocationList( const DWARFUnit *dwarf_cu, const DataExtractor &data, DWARFExpressionList *location_list) { location_list->Clear(); std::unique_ptr loctable_up = dwarf_cu->GetLocationTable(data); Log *log = GetLog(LLDBLog::Expressions); auto lookup_addr = [&](uint32_t index) -> llvm::Optional { addr_t address = dwarf_cu->ReadAddressFromDebugAddrSection(index); if (address == LLDB_INVALID_ADDRESS) return llvm::None; return llvm::object::SectionedAddress{address}; }; auto process_list = [&](llvm::Expected loc) { if (!loc) { LLDB_LOG_ERROR(log, loc.takeError(), "{0}"); return true; } auto buffer_sp = std::make_shared(loc->Expr.data(), loc->Expr.size()); DWARFExpression expr = DWARFExpression(DataExtractor( buffer_sp, data.GetByteOrder(), data.GetAddressByteSize())); location_list->AddExpression(loc->Range->LowPC, loc->Range->HighPC, expr); return true; }; llvm::Error error = loctable_up->visitAbsoluteLocationList( 0, llvm::object::SectionedAddress{dwarf_cu->GetBaseAddress()}, lookup_addr, process_list); location_list->Sort(); if (error) { LLDB_LOG_ERROR(log, std::move(error), "{0}"); return false; } return true; } bool DWARFExpression::MatchesOperand( StackFrame &frame, const Instruction::Operand &operand) const { using namespace OperandMatchers; RegisterContextSP reg_ctx_sp = frame.GetRegisterContext(); if (!reg_ctx_sp) { return false; } DataExtractor opcodes(m_data); lldb::offset_t op_offset = 0; uint8_t opcode = opcodes.GetU8(&op_offset); if (opcode == DW_OP_fbreg) { int64_t offset = opcodes.GetSLEB128(&op_offset); DWARFExpressionList *fb_expr = frame.GetFrameBaseExpression(nullptr); if (!fb_expr) { return false; } auto recurse = [&frame, fb_expr](const Instruction::Operand &child) { return fb_expr->MatchesOperand(frame, child); }; if (!offset && MatchUnaryOp(MatchOpType(Instruction::Operand::Type::Dereference), recurse)(operand)) { return true; } return MatchUnaryOp( MatchOpType(Instruction::Operand::Type::Dereference), MatchBinaryOp(MatchOpType(Instruction::Operand::Type::Sum), MatchImmOp(offset), recurse))(operand); } bool dereference = false; const RegisterInfo *reg = nullptr; int64_t offset = 0; if (opcode >= DW_OP_reg0 && opcode <= DW_OP_reg31) { reg = reg_ctx_sp->GetRegisterInfo(m_reg_kind, opcode - DW_OP_reg0); } else if (opcode >= DW_OP_breg0 && opcode <= DW_OP_breg31) { offset = opcodes.GetSLEB128(&op_offset); reg = reg_ctx_sp->GetRegisterInfo(m_reg_kind, opcode - DW_OP_breg0); } else if (opcode == DW_OP_regx) { uint32_t reg_num = static_cast(opcodes.GetULEB128(&op_offset)); reg = reg_ctx_sp->GetRegisterInfo(m_reg_kind, reg_num); } else if (opcode == DW_OP_bregx) { uint32_t reg_num = static_cast(opcodes.GetULEB128(&op_offset)); offset = opcodes.GetSLEB128(&op_offset); reg = reg_ctx_sp->GetRegisterInfo(m_reg_kind, reg_num); } else { return false; } if (!reg) { return false; } if (dereference) { if (!offset && MatchUnaryOp(MatchOpType(Instruction::Operand::Type::Dereference), MatchRegOp(*reg))(operand)) { return true; } return MatchUnaryOp( MatchOpType(Instruction::Operand::Type::Dereference), MatchBinaryOp(MatchOpType(Instruction::Operand::Type::Sum), MatchRegOp(*reg), MatchImmOp(offset)))(operand); } else { return MatchRegOp(*reg)(operand); } }