//===-- UnwindAssemblyInstEmulation.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 "UnwindAssemblyInstEmulation.h" #include "lldb/Core/Address.h" #include "lldb/Core/Disassembler.h" #include "lldb/Core/DumpDataExtractor.h" #include "lldb/Core/DumpRegisterValue.h" #include "lldb/Core/FormatEntity.h" #include "lldb/Core/PluginManager.h" #include "lldb/Target/ExecutionContext.h" #include "lldb/Target/Process.h" #include "lldb/Target/Target.h" #include "lldb/Target/Thread.h" #include "lldb/Utility/ArchSpec.h" #include "lldb/Utility/DataBufferHeap.h" #include "lldb/Utility/DataExtractor.h" #include "lldb/Utility/LLDBLog.h" #include "lldb/Utility/Log.h" #include "lldb/Utility/Status.h" #include "lldb/Utility/StreamString.h" using namespace lldb; using namespace lldb_private; LLDB_PLUGIN_DEFINE(UnwindAssemblyInstEmulation) // UnwindAssemblyInstEmulation method definitions bool UnwindAssemblyInstEmulation::GetNonCallSiteUnwindPlanFromAssembly( AddressRange &range, Thread &thread, UnwindPlan &unwind_plan) { std::vector function_text(range.GetByteSize()); ProcessSP process_sp(thread.GetProcess()); if (process_sp) { Status error; const bool force_live_memory = true; if (process_sp->GetTarget().ReadMemory( range.GetBaseAddress(), function_text.data(), range.GetByteSize(), error, force_live_memory) != range.GetByteSize()) { return false; } } return GetNonCallSiteUnwindPlanFromAssembly( range, function_text.data(), function_text.size(), unwind_plan); } bool UnwindAssemblyInstEmulation::GetNonCallSiteUnwindPlanFromAssembly( AddressRange &range, uint8_t *opcode_data, size_t opcode_size, UnwindPlan &unwind_plan) { if (opcode_data == nullptr || opcode_size == 0) return false; if (range.GetByteSize() == 0 || !range.GetBaseAddress().IsValid() || !m_inst_emulator_up) return false; // The instruction emulation subclass setup the unwind plan for the first // instruction. m_inst_emulator_up->CreateFunctionEntryUnwind(unwind_plan); // CreateFunctionEntryUnwind should have created the first row. If it doesn't, // then we are done. if (unwind_plan.GetRowCount() == 0) return false; const bool prefer_file_cache = true; DisassemblerSP disasm_sp(Disassembler::DisassembleBytes( m_arch, nullptr, nullptr, nullptr, nullptr, range.GetBaseAddress(), opcode_data, opcode_size, 99999, prefer_file_cache)); if (!disasm_sp) return false; Log *log = GetLog(LLDBLog::Unwind); m_range_ptr = ⦥ m_unwind_plan_ptr = &unwind_plan; const uint32_t addr_byte_size = m_arch.GetAddressByteSize(); const bool show_address = true; const bool show_bytes = true; const bool show_control_flow_kind = false; m_state.cfa_reg_info = *m_inst_emulator_up->GetRegisterInfo( unwind_plan.GetRegisterKind(), unwind_plan.GetInitialCFARegister()); m_state.fp_is_cfa = false; m_state.register_values.clear(); m_pushed_regs.clear(); // Initialize the CFA with a known value. In the 32 bit case it will be // 0x80000000, and in the 64 bit case 0x8000000000000000. We use the address // byte size to be safe for any future address sizes m_initial_sp = (1ull << ((addr_byte_size * 8) - 1)); RegisterValue cfa_reg_value; cfa_reg_value.SetUInt(m_initial_sp, m_state.cfa_reg_info.byte_size); SetRegisterValue(m_state.cfa_reg_info, cfa_reg_value); const InstructionList &inst_list = disasm_sp->GetInstructionList(); const size_t num_instructions = inst_list.GetSize(); if (num_instructions > 0) { Instruction *inst = inst_list.GetInstructionAtIndex(0).get(); const lldb::addr_t base_addr = inst->GetAddress().GetFileAddress(); // Map for storing the unwind state at a given offset. When we see a forward // branch we add a new entry to this map with the actual unwind plan row and // register context for the target address of the branch as the current data // have to be valid for the target address of the branch too if we are in // the same function. std::map saved_unwind_states; // Make a copy of the current instruction Row and save it in m_state so // we can add updates as we process the instructions. m_state.row = *unwind_plan.GetLastRow(); // Add the initial state to the save list with offset 0. auto condition_block_start_state = saved_unwind_states.emplace(0, m_state).first; // The architecture dependent condition code of the last processed // instruction. EmulateInstruction::InstructionCondition last_condition = EmulateInstruction::UnconditionalCondition; for (size_t idx = 0; idx < num_instructions; ++idx) { m_curr_row_modified = false; m_forward_branch_offset = 0; inst = inst_list.GetInstructionAtIndex(idx).get(); if (!inst) continue; lldb::addr_t current_offset = inst->GetAddress().GetFileAddress() - base_addr; auto it = saved_unwind_states.upper_bound(current_offset); assert(it != saved_unwind_states.begin() && "Unwind row for the function entry missing"); --it; // Move it to the row corresponding to the current offset // If the offset of m_curr_row don't match with the offset we see in // saved_unwind_states then we have to update current unwind state to // the saved values. It is happening after we processed an epilogue and a // return to caller instruction. if (it->second.row.GetOffset() != m_state.row.GetOffset()) m_state = it->second; m_inst_emulator_up->SetInstruction(inst->GetOpcode(), inst->GetAddress(), nullptr); if (last_condition != m_inst_emulator_up->GetInstructionCondition()) { // If the last instruction was conditional with a different condition // than the current condition then restore the state. if (last_condition != EmulateInstruction::UnconditionalCondition) { m_state = condition_block_start_state->second; m_state.row.SetOffset(current_offset); // The last instruction might already created a row for this offset // and we want to overwrite it. saved_unwind_states.insert_or_assign(current_offset, m_state); } // We are starting a new conditional block at the actual offset condition_block_start_state = it; } if (log && log->GetVerbose()) { StreamString strm; lldb_private::FormatEntity::Entry format; FormatEntity::Parse("${frame.pc}: ", format); inst->Dump(&strm, inst_list.GetMaxOpcocdeByteSize(), show_address, show_bytes, show_control_flow_kind, nullptr, nullptr, nullptr, &format, 0); log->PutString(strm.GetString()); } last_condition = m_inst_emulator_up->GetInstructionCondition(); m_inst_emulator_up->EvaluateInstruction( eEmulateInstructionOptionIgnoreConditions); // If the current instruction is a branch forward then save the current // CFI information for the offset where we are branching. if (m_forward_branch_offset != 0 && range.ContainsFileAddress(inst->GetAddress().GetFileAddress() + m_forward_branch_offset)) { if (auto [it, inserted] = saved_unwind_states.emplace( current_offset + m_forward_branch_offset, m_state); inserted) it->second.row.SetOffset(current_offset + m_forward_branch_offset); } // Were there any changes to the CFI while evaluating this instruction? if (m_curr_row_modified) { // Save the modified row if we don't already have a CFI row in the // current address if (saved_unwind_states.count(current_offset + inst->GetOpcode().GetByteSize()) == 0) { m_state.row.SetOffset(current_offset + inst->GetOpcode().GetByteSize()); saved_unwind_states.emplace( current_offset + inst->GetOpcode().GetByteSize(), m_state); } } } for (auto &[_, state] : saved_unwind_states) { unwind_plan.InsertRow(std::move(state.row), /*replace_existing=*/true); } } if (log && log->GetVerbose()) { StreamString strm; lldb::addr_t base_addr = range.GetBaseAddress().GetFileAddress(); strm.Printf("Resulting unwind rows for [0x%" PRIx64 " - 0x%" PRIx64 "):", base_addr, base_addr + range.GetByteSize()); unwind_plan.Dump(strm, nullptr, base_addr); log->PutString(strm.GetString()); } return unwind_plan.GetRowCount() > 0; } bool UnwindAssemblyInstEmulation::AugmentUnwindPlanFromCallSite( AddressRange &func, Thread &thread, UnwindPlan &unwind_plan) { return false; } bool UnwindAssemblyInstEmulation::GetFastUnwindPlan(AddressRange &func, Thread &thread, UnwindPlan &unwind_plan) { return false; } bool UnwindAssemblyInstEmulation::FirstNonPrologueInsn( AddressRange &func, const ExecutionContext &exe_ctx, Address &first_non_prologue_insn) { return false; } UnwindAssembly * UnwindAssemblyInstEmulation::CreateInstance(const ArchSpec &arch) { std::unique_ptr inst_emulator_up( EmulateInstruction::FindPlugin(arch, eInstructionTypePrologueEpilogue, nullptr)); // Make sure that all prologue instructions are handled if (inst_emulator_up) return new UnwindAssemblyInstEmulation(arch, inst_emulator_up.release()); return nullptr; } void UnwindAssemblyInstEmulation::Initialize() { PluginManager::RegisterPlugin(GetPluginNameStatic(), GetPluginDescriptionStatic(), CreateInstance); } void UnwindAssemblyInstEmulation::Terminate() { PluginManager::UnregisterPlugin(CreateInstance); } llvm::StringRef UnwindAssemblyInstEmulation::GetPluginDescriptionStatic() { return "Instruction emulation based unwind information."; } uint64_t UnwindAssemblyInstEmulation::MakeRegisterKindValuePair( const RegisterInfo ®_info) { lldb::RegisterKind reg_kind; uint32_t reg_num; if (EmulateInstruction::GetBestRegisterKindAndNumber(®_info, reg_kind, reg_num)) return (uint64_t)reg_kind << 24 | reg_num; return 0ull; } void UnwindAssemblyInstEmulation::SetRegisterValue( const RegisterInfo ®_info, const RegisterValue ®_value) { m_state.register_values[MakeRegisterKindValuePair(reg_info)] = reg_value; } bool UnwindAssemblyInstEmulation::GetRegisterValue(const RegisterInfo ®_info, RegisterValue ®_value) { const uint64_t reg_id = MakeRegisterKindValuePair(reg_info); RegisterValueMap::const_iterator pos = m_state.register_values.find(reg_id); if (pos != m_state.register_values.end()) { reg_value = pos->second; return true; // We had a real value that comes from an opcode that wrote // to it... } // We are making up a value that is recognizable... reg_value.SetUInt(reg_id, reg_info.byte_size); return false; } size_t UnwindAssemblyInstEmulation::ReadMemory( EmulateInstruction *instruction, void *baton, const EmulateInstruction::Context &context, lldb::addr_t addr, void *dst, size_t dst_len) { Log *log = GetLog(LLDBLog::Unwind); if (log && log->GetVerbose()) { StreamString strm; strm.Printf( "UnwindAssemblyInstEmulation::ReadMemory (addr = 0x%16.16" PRIx64 ", dst = %p, dst_len = %" PRIu64 ", context = ", addr, dst, (uint64_t)dst_len); context.Dump(strm, instruction); log->PutString(strm.GetString()); } memset(dst, 0, dst_len); return dst_len; } size_t UnwindAssemblyInstEmulation::WriteMemory( EmulateInstruction *instruction, void *baton, const EmulateInstruction::Context &context, lldb::addr_t addr, const void *dst, size_t dst_len) { if (baton && dst && dst_len) return ((UnwindAssemblyInstEmulation *)baton) ->WriteMemory(instruction, context, addr, dst, dst_len); return 0; } size_t UnwindAssemblyInstEmulation::WriteMemory( EmulateInstruction *instruction, const EmulateInstruction::Context &context, lldb::addr_t addr, const void *dst, size_t dst_len) { DataExtractor data(dst, dst_len, instruction->GetArchitecture().GetByteOrder(), instruction->GetArchitecture().GetAddressByteSize()); Log *log = GetLog(LLDBLog::Unwind); if (log && log->GetVerbose()) { StreamString strm; strm.PutCString("UnwindAssemblyInstEmulation::WriteMemory ("); DumpDataExtractor(data, &strm, 0, eFormatBytes, 1, dst_len, UINT32_MAX, addr, 0, 0); strm.PutCString(", context = "); context.Dump(strm, instruction); log->PutString(strm.GetString()); } switch (context.type) { default: case EmulateInstruction::eContextInvalid: case EmulateInstruction::eContextReadOpcode: case EmulateInstruction::eContextImmediate: case EmulateInstruction::eContextAdjustBaseRegister: case EmulateInstruction::eContextRegisterPlusOffset: case EmulateInstruction::eContextAdjustPC: case EmulateInstruction::eContextRegisterStore: case EmulateInstruction::eContextRegisterLoad: case EmulateInstruction::eContextRelativeBranchImmediate: case EmulateInstruction::eContextAbsoluteBranchRegister: case EmulateInstruction::eContextSupervisorCall: case EmulateInstruction::eContextTableBranchReadMemory: case EmulateInstruction::eContextWriteRegisterRandomBits: case EmulateInstruction::eContextWriteMemoryRandomBits: case EmulateInstruction::eContextArithmetic: case EmulateInstruction::eContextAdvancePC: case EmulateInstruction::eContextReturnFromException: case EmulateInstruction::eContextPopRegisterOffStack: case EmulateInstruction::eContextAdjustStackPointer: break; case EmulateInstruction::eContextPushRegisterOnStack: { uint32_t reg_num = LLDB_INVALID_REGNUM; uint32_t generic_regnum = LLDB_INVALID_REGNUM; assert(context.GetInfoType() == EmulateInstruction::eInfoTypeRegisterToRegisterPlusOffset && "unhandled case, add code to handle this!"); const uint32_t unwind_reg_kind = m_unwind_plan_ptr->GetRegisterKind(); reg_num = context.info.RegisterToRegisterPlusOffset.data_reg .kinds[unwind_reg_kind]; generic_regnum = context.info.RegisterToRegisterPlusOffset.data_reg .kinds[eRegisterKindGeneric]; if (reg_num != LLDB_INVALID_REGNUM && generic_regnum != LLDB_REGNUM_GENERIC_SP) { if (m_pushed_regs.try_emplace(reg_num, addr).second) { const int32_t offset = addr - m_initial_sp; m_state.row.SetRegisterLocationToAtCFAPlusOffset(reg_num, offset, /*can_replace=*/true); m_curr_row_modified = true; } } } break; } return dst_len; } bool UnwindAssemblyInstEmulation::ReadRegister(EmulateInstruction *instruction, void *baton, const RegisterInfo *reg_info, RegisterValue ®_value) { if (baton && reg_info) return ((UnwindAssemblyInstEmulation *)baton) ->ReadRegister(instruction, reg_info, reg_value); return false; } bool UnwindAssemblyInstEmulation::ReadRegister(EmulateInstruction *instruction, const RegisterInfo *reg_info, RegisterValue ®_value) { bool synthetic = GetRegisterValue(*reg_info, reg_value); Log *log = GetLog(LLDBLog::Unwind); if (log && log->GetVerbose()) { StreamString strm; strm.Printf("UnwindAssemblyInstEmulation::ReadRegister (name = \"%s\") => " "synthetic_value = %i, value = ", reg_info->name, synthetic); DumpRegisterValue(reg_value, strm, *reg_info, false, false, eFormatDefault); log->PutString(strm.GetString()); } return true; } bool UnwindAssemblyInstEmulation::WriteRegister( EmulateInstruction *instruction, void *baton, const EmulateInstruction::Context &context, const RegisterInfo *reg_info, const RegisterValue ®_value) { if (baton && reg_info) return ((UnwindAssemblyInstEmulation *)baton) ->WriteRegister(instruction, context, reg_info, reg_value); return false; } bool UnwindAssemblyInstEmulation::WriteRegister( EmulateInstruction *instruction, const EmulateInstruction::Context &context, const RegisterInfo *reg_info, const RegisterValue ®_value) { Log *log = GetLog(LLDBLog::Unwind); if (log && log->GetVerbose()) { StreamString strm; strm.Printf( "UnwindAssemblyInstEmulation::WriteRegister (name = \"%s\", value = ", reg_info->name); DumpRegisterValue(reg_value, strm, *reg_info, false, false, eFormatDefault); strm.PutCString(", context = "); context.Dump(strm, instruction); log->PutString(strm.GetString()); } SetRegisterValue(*reg_info, reg_value); switch (context.type) { case EmulateInstruction::eContextInvalid: case EmulateInstruction::eContextReadOpcode: case EmulateInstruction::eContextImmediate: case EmulateInstruction::eContextAdjustBaseRegister: case EmulateInstruction::eContextRegisterPlusOffset: case EmulateInstruction::eContextAdjustPC: case EmulateInstruction::eContextRegisterStore: case EmulateInstruction::eContextSupervisorCall: case EmulateInstruction::eContextTableBranchReadMemory: case EmulateInstruction::eContextWriteRegisterRandomBits: case EmulateInstruction::eContextWriteMemoryRandomBits: case EmulateInstruction::eContextAdvancePC: case EmulateInstruction::eContextReturnFromException: case EmulateInstruction::eContextPushRegisterOnStack: case EmulateInstruction::eContextRegisterLoad: // { // const uint32_t reg_num = // reg_info->kinds[m_unwind_plan_ptr->GetRegisterKind()]; // if (reg_num != LLDB_INVALID_REGNUM) // { // const bool can_replace_only_if_unspecified = true; // // m_curr_row.SetRegisterLocationToUndefined (reg_num, // can_replace_only_if_unspecified, // can_replace_only_if_unspecified); // m_curr_row_modified = true; // } // } break; case EmulateInstruction::eContextArithmetic: { // If we adjusted the current frame pointer by a constant then adjust the // CFA offset // with the same amount. lldb::RegisterKind kind = m_unwind_plan_ptr->GetRegisterKind(); if (m_state.fp_is_cfa && reg_info->kinds[kind] == m_state.cfa_reg_info.kinds[kind] && context.GetInfoType() == EmulateInstruction::eInfoTypeRegisterPlusOffset && context.info.RegisterPlusOffset.reg.kinds[kind] == m_state.cfa_reg_info.kinds[kind]) { const int64_t offset = context.info.RegisterPlusOffset.signed_offset; m_state.row.GetCFAValue().IncOffset(-1 * offset); m_curr_row_modified = true; } } break; case EmulateInstruction::eContextAbsoluteBranchRegister: case EmulateInstruction::eContextRelativeBranchImmediate: { if (context.GetInfoType() == EmulateInstruction::eInfoTypeISAAndImmediate && context.info.ISAAndImmediate.unsigned_data32 > 0) { m_forward_branch_offset = context.info.ISAAndImmediateSigned.signed_data32; } else if (context.GetInfoType() == EmulateInstruction::eInfoTypeISAAndImmediateSigned && context.info.ISAAndImmediateSigned.signed_data32 > 0) { m_forward_branch_offset = context.info.ISAAndImmediate.unsigned_data32; } else if (context.GetInfoType() == EmulateInstruction::eInfoTypeImmediate && context.info.unsigned_immediate > 0) { m_forward_branch_offset = context.info.unsigned_immediate; } else if (context.GetInfoType() == EmulateInstruction::eInfoTypeImmediateSigned && context.info.signed_immediate > 0) { m_forward_branch_offset = context.info.signed_immediate; } } break; case EmulateInstruction::eContextPopRegisterOffStack: { const uint32_t reg_num = reg_info->kinds[m_unwind_plan_ptr->GetRegisterKind()]; const uint32_t generic_regnum = reg_info->kinds[eRegisterKindGeneric]; if (reg_num != LLDB_INVALID_REGNUM && generic_regnum != LLDB_REGNUM_GENERIC_SP) { switch (context.GetInfoType()) { case EmulateInstruction::eInfoTypeAddress: if (auto it = m_pushed_regs.find(reg_num); it != m_pushed_regs.end() && context.info.address == it->second) { m_state.row.SetRegisterLocationToSame(reg_num, false /*must_replace*/); m_curr_row_modified = true; // FP has been restored to its original value, we are back // to using SP to calculate the CFA. if (m_state.fp_is_cfa) { m_state.fp_is_cfa = false; lldb::RegisterKind sp_reg_kind = eRegisterKindGeneric; uint32_t sp_reg_num = LLDB_REGNUM_GENERIC_SP; RegisterInfo sp_reg_info = *m_inst_emulator_up->GetRegisterInfo(sp_reg_kind, sp_reg_num); RegisterValue sp_reg_val; if (GetRegisterValue(sp_reg_info, sp_reg_val)) { m_state.cfa_reg_info = sp_reg_info; const uint32_t cfa_reg_num = sp_reg_info.kinds[m_unwind_plan_ptr->GetRegisterKind()]; assert(cfa_reg_num != LLDB_INVALID_REGNUM); m_state.row.GetCFAValue().SetIsRegisterPlusOffset( cfa_reg_num, m_initial_sp - sp_reg_val.GetAsUInt64()); } } } break; case EmulateInstruction::eInfoTypeISA: assert( (generic_regnum == LLDB_REGNUM_GENERIC_PC || generic_regnum == LLDB_REGNUM_GENERIC_FLAGS) && "eInfoTypeISA used for popping a register other the PC/FLAGS"); if (generic_regnum != LLDB_REGNUM_GENERIC_FLAGS) { m_state.row.SetRegisterLocationToSame(reg_num, false /*must_replace*/); m_curr_row_modified = true; } break; default: assert(false && "unhandled case, add code to handle this!"); break; } } } break; case EmulateInstruction::eContextSetFramePointer: if (!m_state.fp_is_cfa) { m_state.fp_is_cfa = true; m_state.cfa_reg_info = *reg_info; const uint32_t cfa_reg_num = reg_info->kinds[m_unwind_plan_ptr->GetRegisterKind()]; assert(cfa_reg_num != LLDB_INVALID_REGNUM); m_state.row.GetCFAValue().SetIsRegisterPlusOffset( cfa_reg_num, m_initial_sp - reg_value.GetAsUInt64()); m_curr_row_modified = true; } break; case EmulateInstruction::eContextRestoreStackPointer: if (m_state.fp_is_cfa) { m_state.fp_is_cfa = false; m_state.cfa_reg_info = *reg_info; const uint32_t cfa_reg_num = reg_info->kinds[m_unwind_plan_ptr->GetRegisterKind()]; assert(cfa_reg_num != LLDB_INVALID_REGNUM); m_state.row.GetCFAValue().SetIsRegisterPlusOffset( cfa_reg_num, m_initial_sp - reg_value.GetAsUInt64()); m_curr_row_modified = true; } break; case EmulateInstruction::eContextAdjustStackPointer: // If we have created a frame using the frame pointer, don't follow // subsequent adjustments to the stack pointer. if (!m_state.fp_is_cfa) { m_state.row.GetCFAValue().SetIsRegisterPlusOffset( m_state.row.GetCFAValue().GetRegisterNumber(), m_initial_sp - reg_value.GetAsUInt64()); m_curr_row_modified = true; } break; } return true; }