bool
DWARFCallFrameInfo::FDEToUnwindPlan (dw_offset_t offset, Address startaddr, UnwindPlan& unwind_plan)
{
dw_offset_t current_entry = offset;
if (m_section_sp.get() == NULL || m_section_sp->IsEncrypted())
return false;
if (m_cfi_data_initialized == false)
GetCFIData();
uint32_t length = m_cfi_data.GetU32 (&offset);
dw_offset_t cie_offset = m_cfi_data.GetU32 (&offset);
assert (cie_offset != 0 && cie_offset != UINT32_MAX);
// Translate the CIE_id from the eh_frame format, which
// is relative to the FDE offset, into a __eh_frame section
// offset
if (m_is_eh_frame)
{
unwind_plan.SetSourceName ("eh_frame CFI");
cie_offset = current_entry + 4 - cie_offset;
unwind_plan.SetUnwindPlanValidAtAllInstructions (eLazyBoolNo);
}
else
{
unwind_plan.SetSourceName ("DWARF CFI");
// In theory the debug_frame info should be valid at all call sites
// ("asynchronous unwind info" as it is sometimes called) but in practice
// gcc et al all emit call frame info for the prologue and call sites, but
// not for the epilogue or all the other locations during the function reliably.
unwind_plan.SetUnwindPlanValidAtAllInstructions (eLazyBoolNo);
}
unwind_plan.SetSourcedFromCompiler (eLazyBoolYes);
const CIE *cie = GetCIE (cie_offset);
assert (cie != NULL);
const dw_offset_t end_offset = current_entry + length + 4;
const lldb::addr_t pc_rel_addr = m_section_sp->GetFileAddress();
const lldb::addr_t text_addr = LLDB_INVALID_ADDRESS;
const lldb::addr_t data_addr = LLDB_INVALID_ADDRESS;
lldb::addr_t range_base = m_cfi_data.GetGNUEHPointer(&offset, cie->ptr_encoding, pc_rel_addr, text_addr, data_addr);
lldb::addr_t range_len = m_cfi_data.GetGNUEHPointer(&offset, cie->ptr_encoding & DW_EH_PE_MASK_ENCODING, pc_rel_addr, text_addr, data_addr);
AddressRange range (range_base, m_objfile.GetAddressByteSize(), m_objfile.GetSectionList());
range.SetByteSize (range_len);
if (cie->augmentation[0] == 'z')
{
uint32_t aug_data_len = (uint32_t)m_cfi_data.GetULEB128(&offset);
offset += aug_data_len;
}
uint32_t reg_num = 0;
int32_t op_offset = 0;
uint32_t code_align = cie->code_align;
int32_t data_align = cie->data_align;
unwind_plan.SetPlanValidAddressRange (range);
UnwindPlan::Row *cie_initial_row = new UnwindPlan::Row;
*cie_initial_row = cie->initial_row;
UnwindPlan::RowSP row(cie_initial_row);
unwind_plan.SetRegisterKind (m_reg_kind);
unwind_plan.SetReturnAddressRegister (cie->return_addr_reg_num);
UnwindPlan::Row::RegisterLocation reg_location;
while (m_cfi_data.ValidOffset(offset) && offset < end_offset)
{
uint8_t inst = m_cfi_data.GetU8(&offset);
uint8_t primary_opcode = inst & 0xC0;
uint8_t extended_opcode = inst & 0x3F;
if (primary_opcode)
{
switch (primary_opcode)
{
case DW_CFA_advance_loc : // (Row Creation Instruction)
{ // 0x40 - high 2 bits are 0x1, lower 6 bits are delta
// takes a single argument that represents a constant delta. The
// required action is to create a new table row with a location
// value that is computed by taking the current entry's location
// value and adding (delta * code_align). All other
// values in the new row are initially identical to the current row.
unwind_plan.AppendRow(row);
UnwindPlan::Row *newrow = new UnwindPlan::Row;
*newrow = *row.get();
row.reset (newrow);
row->SlideOffset(extended_opcode * code_align);
}
break;
case DW_CFA_offset :
{ // 0x80 - high 2 bits are 0x2, lower 6 bits are register
// takes two arguments: an unsigned LEB128 constant representing a
// factored offset and a register number. The required action is to
// change the rule for the register indicated by the register number
// to be an offset(N) rule with a value of
// (N = factored offset * data_align).
reg_num = extended_opcode;
op_offset = (int32_t)m_cfi_data.GetULEB128(&offset) * data_align;
reg_location.SetAtCFAPlusOffset(op_offset);
row->SetRegisterInfo (reg_num, reg_location);
}
break;
case DW_CFA_restore :
{ // 0xC0 - high 2 bits are 0x3, lower 6 bits are register
// takes a single argument that represents a register number. The
// required action is to change the rule for the indicated register
// to the rule assigned it by the initial_instructions in the CIE.
reg_num = extended_opcode;
// We only keep enough register locations around to
// unwind what is in our thread, and these are organized
// by the register index in that state, so we need to convert our
// GCC register number from the EH frame info, to a register index
if (unwind_plan.IsValidRowIndex(0) && unwind_plan.GetRowAtIndex(0)->GetRegisterInfo(reg_num, reg_location))
row->SetRegisterInfo (reg_num, reg_location);
}
break;
}
}
else
{
switch (extended_opcode)
{
case DW_CFA_nop : // 0x0
break;
case DW_CFA_set_loc : // 0x1 (Row Creation Instruction)
{
// DW_CFA_set_loc takes a single argument that represents an address.
// The required action is to create a new table row using the
// specified address as the location. All other values in the new row
// are initially identical to the current row. The new location value
// should always be greater than the current one.
unwind_plan.AppendRow(row);
UnwindPlan::Row *newrow = new UnwindPlan::Row;
*newrow = *row.get();
row.reset (newrow);
row->SetOffset(m_cfi_data.GetPointer(&offset) - startaddr.GetFileAddress());
}
break;
case DW_CFA_advance_loc1 : // 0x2 (Row Creation Instruction)
{
// takes a single uword argument that represents a constant delta.
// This instruction is identical to DW_CFA_advance_loc except for the
// encoding and size of the delta argument.
unwind_plan.AppendRow(row);
UnwindPlan::Row *newrow = new UnwindPlan::Row;
*newrow = *row.get();
row.reset (newrow);
row->SlideOffset (m_cfi_data.GetU8(&offset) * code_align);
}
break;
case DW_CFA_advance_loc2 : // 0x3 (Row Creation Instruction)
{
// takes a single uword argument that represents a constant delta.
// This instruction is identical to DW_CFA_advance_loc except for the
// encoding and size of the delta argument.
unwind_plan.AppendRow(row);
UnwindPlan::Row *newrow = new UnwindPlan::Row;
*newrow = *row.get();
row.reset (newrow);
row->SlideOffset (m_cfi_data.GetU16(&offset) * code_align);
}
break;
case DW_CFA_advance_loc4 : // 0x4 (Row Creation Instruction)
{
// takes a single uword argument that represents a constant delta.
// This instruction is identical to DW_CFA_advance_loc except for the
// encoding and size of the delta argument.
unwind_plan.AppendRow(row);
UnwindPlan::Row *newrow = new UnwindPlan::Row;
*newrow = *row.get();
row.reset (newrow);
row->SlideOffset (m_cfi_data.GetU32(&offset) * code_align);
}
break;
case DW_CFA_offset_extended : // 0x5
{
// takes two unsigned LEB128 arguments representing a register number
// and a factored offset. This instruction is identical to DW_CFA_offset
// except for the encoding and size of the register argument.
reg_num = (uint32_t)m_cfi_data.GetULEB128(&offset);
op_offset = (int32_t)m_cfi_data.GetULEB128(&offset) * data_align;
reg_location.SetAtCFAPlusOffset(op_offset);
row->SetRegisterInfo (reg_num, reg_location);
}
break;
case DW_CFA_restore_extended : // 0x6
{
// takes a single unsigned LEB128 argument that represents a register
// number. This instruction is identical to DW_CFA_restore except for
// the encoding and size of the register argument.
reg_num = (uint32_t)m_cfi_data.GetULEB128(&offset);
if (unwind_plan.IsValidRowIndex(0) && unwind_plan.GetRowAtIndex(0)->GetRegisterInfo(reg_num, reg_location))
row->SetRegisterInfo (reg_num, reg_location);
}
break;
case DW_CFA_undefined : // 0x7
{
// takes a single unsigned LEB128 argument that represents a register
// number. The required action is to set the rule for the specified
// register to undefined.
reg_num = (uint32_t)m_cfi_data.GetULEB128(&offset);
reg_location.SetUndefined();
row->SetRegisterInfo (reg_num, reg_location);
}
break;
case DW_CFA_same_value : // 0x8
{
// takes a single unsigned LEB128 argument that represents a register
// number. The required action is to set the rule for the specified
// register to same value.
reg_num = (uint32_t)m_cfi_data.GetULEB128(&offset);
reg_location.SetSame();
row->SetRegisterInfo (reg_num, reg_location);
}
break;
case DW_CFA_register : // 0x9
{
// takes two unsigned LEB128 arguments representing register numbers.
// The required action is to set the rule for the first register to be
// the second register.
reg_num = (uint32_t)m_cfi_data.GetULEB128(&offset);
uint32_t other_reg_num = (uint32_t)m_cfi_data.GetULEB128(&offset);
reg_location.SetInRegister(other_reg_num);
row->SetRegisterInfo (reg_num, reg_location);
}
break;
case DW_CFA_remember_state : // 0xA
{
// These instructions define a stack of information. Encountering the
// DW_CFA_remember_state instruction means to save the rules for every
// register on the current row on the stack. Encountering the
// DW_CFA_restore_state instruction means to pop the set of rules off
// the stack and place them in the current row. (This operation is
// useful for compilers that move epilogue code into the body of a
// function.)
unwind_plan.AppendRow (row);
UnwindPlan::Row *newrow = new UnwindPlan::Row;
*newrow = *row.get();
row.reset (newrow);
}
break;
case DW_CFA_restore_state : // 0xB
// These instructions define a stack of information. Encountering the
// DW_CFA_remember_state instruction means to save the rules for every
// register on the current row on the stack. Encountering the
// DW_CFA_restore_state instruction means to pop the set of rules off
// the stack and place them in the current row. (This operation is
// useful for compilers that move epilogue code into the body of a
// function.)
{
row = unwind_plan.GetRowAtIndex(unwind_plan.GetRowCount() - 1);
}
break;
case DW_CFA_def_cfa : // 0xC (CFA Definition Instruction)
{
// Takes two unsigned LEB128 operands representing a register
// number and a (non-factored) offset. The required action
// is to define the current CFA rule to use the provided
// register and offset.
reg_num = (uint32_t)m_cfi_data.GetULEB128(&offset);
op_offset = (int32_t)m_cfi_data.GetULEB128(&offset);
row->SetCFARegister (reg_num);
row->SetCFAOffset (op_offset);
}
break;
case DW_CFA_def_cfa_register : // 0xD (CFA Definition Instruction)
{
// takes a single unsigned LEB128 argument representing a register
// number. The required action is to define the current CFA rule to
// use the provided register (but to keep the old offset).
reg_num = (uint32_t)m_cfi_data.GetULEB128(&offset);
row->SetCFARegister (reg_num);
}
break;
case DW_CFA_def_cfa_offset : // 0xE (CFA Definition Instruction)
{
// Takes a single unsigned LEB128 operand representing a
// (non-factored) offset. The required action is to define
// the current CFA rule to use the provided offset (but
// to keep the old register).
op_offset = (int32_t)m_cfi_data.GetULEB128(&offset);
row->SetCFAOffset (op_offset);
}
break;
case DW_CFA_def_cfa_expression : // 0xF (CFA Definition Instruction)
{
size_t block_len = (size_t)m_cfi_data.GetULEB128(&offset);
offset += (uint32_t)block_len;
}
break;
case DW_CFA_expression : // 0x10
{
// Takes two operands: an unsigned LEB128 value representing
// a register number, and a DW_FORM_block value representing a DWARF
// expression. The required action is to change the rule for the
// register indicated by the register number to be an expression(E)
// rule where E is the DWARF expression. That is, the DWARF
// expression computes the address. The value of the CFA is
// pushed on the DWARF evaluation stack prior to execution of
// the DWARF expression.
reg_num = (uint32_t)m_cfi_data.GetULEB128(&offset);
uint32_t block_len = (uint32_t)m_cfi_data.GetULEB128(&offset);
const uint8_t *block_data = (uint8_t *)m_cfi_data.GetData(&offset, block_len);
reg_location.SetAtDWARFExpression(block_data, block_len);
row->SetRegisterInfo (reg_num, reg_location);
}
break;
case DW_CFA_offset_extended_sf : // 0x11
{
// takes two operands: an unsigned LEB128 value representing a
// register number and a signed LEB128 factored offset. This
// instruction is identical to DW_CFA_offset_extended except
//that the second operand is signed and factored.
reg_num = (uint32_t)m_cfi_data.GetULEB128(&offset);
op_offset = (int32_t)m_cfi_data.GetSLEB128(&offset) * data_align;
reg_location.SetAtCFAPlusOffset(op_offset);
row->SetRegisterInfo (reg_num, reg_location);
}
break;
case DW_CFA_def_cfa_sf : // 0x12 (CFA Definition Instruction)
{
// Takes two operands: an unsigned LEB128 value representing
// a register number and a signed LEB128 factored offset.
// This instruction is identical to DW_CFA_def_cfa except
// that the second operand is signed and factored.
reg_num = (uint32_t)m_cfi_data.GetULEB128(&offset);
op_offset = (int32_t)m_cfi_data.GetSLEB128(&offset) * data_align;
row->SetCFARegister (reg_num);
row->SetCFAOffset (op_offset);
}
break;
case DW_CFA_def_cfa_offset_sf : // 0x13 (CFA Definition Instruction)
{
// takes a signed LEB128 operand representing a factored
// offset. This instruction is identical to DW_CFA_def_cfa_offset
// except that the operand is signed and factored.
op_offset = (int32_t)m_cfi_data.GetSLEB128(&offset) * data_align;
row->SetCFAOffset (op_offset);
}
break;
case DW_CFA_val_expression : // 0x16
{
// takes two operands: an unsigned LEB128 value representing a register
// number, and a DW_FORM_block value representing a DWARF expression.
// The required action is to change the rule for the register indicated
// by the register number to be a val_expression(E) rule where E is the
// DWARF expression. That is, the DWARF expression computes the value of
// the given register. The value of the CFA is pushed on the DWARF
// evaluation stack prior to execution of the DWARF expression.
reg_num = (uint32_t)m_cfi_data.GetULEB128(&offset);
uint32_t block_len = (uint32_t)m_cfi_data.GetULEB128(&offset);
const uint8_t* block_data = (uint8_t*)m_cfi_data.GetData(&offset, block_len);
//#if defined(__i386__) || defined(__x86_64__)
// // The EH frame info for EIP and RIP contains code that looks for traps to
// // be a specific type and increments the PC.
// // For i386:
// // DW_CFA_val_expression where:
// // eip = DW_OP_breg6(+28), DW_OP_deref, DW_OP_dup, DW_OP_plus_uconst(0x34),
// // DW_OP_deref, DW_OP_swap, DW_OP_plus_uconst(0), DW_OP_deref,
// // DW_OP_dup, DW_OP_lit3, DW_OP_ne, DW_OP_swap, DW_OP_lit4, DW_OP_ne,
// // DW_OP_and, DW_OP_plus
// // This basically does a:
// // eip = ucontenxt.mcontext32->gpr.eip;
// // if (ucontenxt.mcontext32->exc.trapno != 3 && ucontenxt.mcontext32->exc.trapno != 4)
// // eip++;
// //
// // For x86_64:
// // DW_CFA_val_expression where:
// // rip = DW_OP_breg3(+48), DW_OP_deref, DW_OP_dup, DW_OP_plus_uconst(0x90), DW_OP_deref,
// // DW_OP_swap, DW_OP_plus_uconst(0), DW_OP_deref_size(4), DW_OP_dup, DW_OP_lit3,
// // DW_OP_ne, DW_OP_swap, DW_OP_lit4, DW_OP_ne, DW_OP_and, DW_OP_plus
// // This basically does a:
// // rip = ucontenxt.mcontext64->gpr.rip;
// // if (ucontenxt.mcontext64->exc.trapno != 3 && ucontenxt.mcontext64->exc.trapno != 4)
// // rip++;
// // The trap comparisons and increments are not needed as it hoses up the unwound PC which
// // is expected to point at least past the instruction that causes the fault/trap. So we
// // take it out by trimming the expression right at the first "DW_OP_swap" opcodes
// if (block_data != NULL && thread->GetPCRegNum(Thread::GCC) == reg_num)
// {
// if (thread->Is64Bit())
// {
// if (block_len > 9 && block_data[8] == DW_OP_swap && block_data[9] == DW_OP_plus_uconst)
// block_len = 8;
// }
// else
// {
// if (block_len > 8 && block_data[7] == DW_OP_swap && block_data[8] == DW_OP_plus_uconst)
// block_len = 7;
// }
// }
//#endif
reg_location.SetIsDWARFExpression(block_data, block_len);
row->SetRegisterInfo (reg_num, reg_location);
}
break;
case DW_CFA_val_offset : // 0x14
case DW_CFA_val_offset_sf : // 0x15
default:
break;
}
}
}
unwind_plan.AppendRow(row);
return true;
}
bool
UnwindAssemblyInstEmulation::GetNonCallSiteUnwindPlanFromAssembly (AddressRange& range,
Thread& thread,
UnwindPlan& unwind_plan)
{
if (range.GetByteSize() > 0 &&
range.GetBaseAddress().IsValid() &&
m_inst_emulator_ap.get())
{
// The instruction emulation subclass setup the unwind plan for the
// first instruction.
m_inst_emulator_ap->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;
ExecutionContext exe_ctx;
thread.CalculateExecutionContext(exe_ctx);
const bool prefer_file_cache = true;
DisassemblerSP disasm_sp (Disassembler::DisassembleRange (m_arch,
NULL,
NULL,
exe_ctx,
range,
prefer_file_cache));
Log *log(GetLogIfAllCategoriesSet (LIBLLDB_LOG_UNWIND));
if (disasm_sp)
{
m_range_ptr = ⦥
m_thread_ptr = &thread;
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;
m_inst_emulator_ap->GetRegisterInfo (unwind_plan.GetRegisterKind(),
unwind_plan.GetInitialCFARegister(),
m_cfa_reg_info);
m_fp_is_cfa = false;
m_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_cfa_reg_info.byte_size);
SetRegisterValue (m_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 plan row and the value of the registers 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<lldb::addr_t, std::pair<UnwindPlan::RowSP, RegisterValueMap>> saved_unwind_states;
// Make a copy of the current instruction Row and save it in m_curr_row
// so we can add updates as we process the instructions.
UnwindPlan::RowSP last_row = unwind_plan.GetLastRow();
UnwindPlan::Row *newrow = new UnwindPlan::Row;
if (last_row.get())
*newrow = *last_row.get();
m_curr_row.reset(newrow);
// Add the initial state to the save list with offset 0.
saved_unwind_states.insert({0, {last_row, m_register_values}});
// cache the pc register number (in whatever register numbering this UnwindPlan uses) for
// quick reference during instruction parsing.
uint32_t pc_reg_num = LLDB_INVALID_REGNUM;
RegisterInfo pc_reg_info;
if (m_inst_emulator_ap->GetRegisterInfo (eRegisterKindGeneric, LLDB_REGNUM_GENERIC_PC, pc_reg_info))
pc_reg_num = pc_reg_info.kinds[unwind_plan.GetRegisterKind()];
else
pc_reg_num = LLDB_INVALID_REGNUM;
// cache the return address register number (in whatever register numbering this UnwindPlan uses) for
// quick reference during instruction parsing.
uint32_t ra_reg_num = LLDB_INVALID_REGNUM;
RegisterInfo ra_reg_info;
if (m_inst_emulator_ap->GetRegisterInfo (eRegisterKindGeneric, LLDB_REGNUM_GENERIC_RA, ra_reg_info))
ra_reg_num = ra_reg_info.kinds[unwind_plan.GetRegisterKind()];
else
ra_reg_num = LLDB_INVALID_REGNUM;
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)
{
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 m_curr_row and m_register_values based on the saved values. It
// is happenning after we processed an epilogue and a return to caller instruction.
if (it->second.first->GetOffset() != m_curr_row->GetOffset())
{
UnwindPlan::Row *newrow = new UnwindPlan::Row;
*newrow = *it->second.first;
m_curr_row.reset(newrow);
m_register_values = it->second.second;;
}
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, NULL, NULL, NULL, &format, 0);
log->PutCString (strm.GetData());
}
m_inst_emulator_ap->SetInstruction (inst->GetOpcode(),
inst->GetAddress(),
exe_ctx.GetTargetPtr());
m_inst_emulator_ap->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))
{
auto newrow = std::make_shared<UnwindPlan::Row>(*m_curr_row.get());
newrow->SetOffset(current_offset + m_forward_branch_offset);
saved_unwind_states.insert({current_offset + m_forward_branch_offset, {newrow, m_register_values}});
unwind_plan.InsertRow(newrow);
}
// 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 currennt address
if (saved_unwind_states.count(current_offset + inst->GetOpcode().GetByteSize()) == 0)
{
m_curr_row->SetOffset (current_offset + inst->GetOpcode().GetByteSize());
unwind_plan.InsertRow (m_curr_row);
saved_unwind_states.insert({current_offset + inst->GetOpcode().GetByteSize(), {m_curr_row, m_register_values}});
// Allocate a new Row for m_curr_row, copy the current state into it
UnwindPlan::Row *newrow = new UnwindPlan::Row;
*newrow = *m_curr_row.get();
m_curr_row.reset(newrow);
}
}
}
}
}
// FIXME: The DisassemblerLLVMC has a reference cycle and won't go away if it has any active instructions.
// I'll fix that but for now, just clear the list and it will go away nicely.
disasm_sp->GetInstructionList().Clear();
}
if (log && log->GetVerbose ())
{
StreamString strm;
lldb::addr_t base_addr = range.GetBaseAddress().GetLoadAddress(thread.CalculateTarget().get());
strm.Printf ("Resulting unwind rows for [0x%" PRIx64 " - 0x%" PRIx64 "):", base_addr, base_addr + range.GetByteSize());
unwind_plan.Dump(strm, &thread, base_addr);
log->PutCString (strm.GetData());
}
return unwind_plan.GetRowCount() > 0;
}
return false;
}
bool
UnwindAssemblyInstEmulation::GetNonCallSiteUnwindPlanFromAssembly (AddressRange& range,
Thread& thread,
UnwindPlan& unwind_plan)
{
if (range.GetByteSize() > 0 &&
range.GetBaseAddress().IsValid() &&
m_inst_emulator_ap.get())
{
// The the instruction emulation subclass setup the unwind plan for the
// first instruction.
m_inst_emulator_ap->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;
ExecutionContext exe_ctx;
thread.CalculateExecutionContext(exe_ctx);
DisassemblerSP disasm_sp (Disassembler::DisassembleRange (m_arch,
NULL,
exe_ctx,
range));
LogSP log(GetLogIfAllCategoriesSet (LIBLLDB_LOG_UNWIND));
if (disasm_sp)
{
m_range_ptr = ⦥
m_thread_ptr = &thread;
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 raw = false;
// 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 addresss sizes
m_inst_emulator_ap->GetRegisterInfo (unwind_plan.GetRegisterKind(),
unwind_plan.GetInitialCFARegister(),
m_cfa_reg_info);
m_fp_is_cfa = false;
m_register_values.clear();
m_pushed_regs.clear();
m_initial_sp = (1ull << ((addr_byte_size * 8) - 1));
RegisterValue cfa_reg_value;
cfa_reg_value.SetUInt (m_initial_sp, m_cfa_reg_info.byte_size);
SetRegisterValue (m_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 addr_t base_addr = inst->GetAddress().GetFileAddress();
// Initialize the current row with the one row that was created
// from the CreateFunctionEntryUnwind call above...
m_curr_row = unwind_plan.GetLastRow();
for (size_t idx=0; idx<num_instructions; ++idx)
{
inst = inst_list.GetInstructionAtIndex (idx).get();
if (inst)
{
if (log && log->GetVerbose ())
{
StreamString strm;
inst->Dump(&strm, inst_list.GetMaxOpcocdeByteSize (), show_address, show_bytes, &exe_ctx, raw);
log->PutCString (strm.GetData());
}
m_inst_emulator_ap->SetInstruction (inst->GetOpcode(),
inst->GetAddress(),
exe_ctx.GetTargetPtr());
m_inst_emulator_ap->EvaluateInstruction (eEmulateInstructionOptionIgnoreConditions);
if (unwind_plan.GetLastRow() != m_curr_row)
{
// Be sure to not edit the offset unless our row has changed
// so that the "!=" call above doesn't trigger every time
m_curr_row.SetOffset (inst->GetAddress().GetFileAddress() + inst->GetOpcode().GetByteSize() - base_addr);
// Append the new row
unwind_plan.AppendRow (m_curr_row);
}
}
}
}
}
if (log && log->GetVerbose ())
{
StreamString strm;
lldb::addr_t base_addr = range.GetBaseAddress().GetLoadAddress(&thread.GetProcess().GetTarget());
strm.Printf ("Resulting unwind rows for [0x%llx - 0x%llx):", base_addr, base_addr + range.GetByteSize());
unwind_plan.Dump(strm, &thread, base_addr);
log->PutCString (strm.GetData());
}
return unwind_plan.GetRowCount() > 0;
}
return false;
}
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_ap.get()) {
// The instruction emulation subclass setup the unwind plan for the
// first instruction.
m_inst_emulator_ap->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, NULL, NULL, range.GetBaseAddress(), opcode_data, opcode_size,
99999, prefer_file_cache));
Log *log(GetLogIfAllCategoriesSet(LIBLLDB_LOG_UNWIND));
if (disasm_sp) {
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;
m_inst_emulator_ap->GetRegisterInfo(unwind_plan.GetRegisterKind(),
unwind_plan.GetInitialCFARegister(),
m_cfa_reg_info);
m_fp_is_cfa = false;
m_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_cfa_reg_info.byte_size);
SetRegisterValue(m_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 plan row and the value of the registers 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<lldb::addr_t, std::pair<UnwindPlan::RowSP, RegisterValueMap>>
saved_unwind_states;
// Make a copy of the current instruction Row and save it in m_curr_row
// so we can add updates as we process the instructions.
UnwindPlan::RowSP last_row = unwind_plan.GetLastRow();
UnwindPlan::Row *newrow = new UnwindPlan::Row;
if (last_row.get())
*newrow = *last_row.get();
m_curr_row.reset(newrow);
// Add the initial state to the save list with offset 0.
saved_unwind_states.insert({0, {last_row, m_register_values}});
// cache the pc register number (in whatever register numbering this
// UnwindPlan uses) for
// quick reference during instruction parsing.
RegisterInfo pc_reg_info;
m_inst_emulator_ap->GetRegisterInfo(
eRegisterKindGeneric, LLDB_REGNUM_GENERIC_PC, pc_reg_info);
// cache the return address register number (in whatever register
// numbering this UnwindPlan uses) for
// quick reference during instruction parsing.
RegisterInfo ra_reg_info;
m_inst_emulator_ap->GetRegisterInfo(
eRegisterKindGeneric, LLDB_REGNUM_GENERIC_RA, ra_reg_info);
// The architecture dependent condition code of the last processed
// instruction.
EmulateInstruction::InstructionCondition last_condition =
EmulateInstruction::UnconditionalCondition;
lldb::addr_t condition_block_start_offset = 0;
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) {
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 m_curr_row and m_register_values based on
// the saved values. It
// is happenning after we processed an epilogue and a return to
// caller instruction.
if (it->second.first->GetOffset() != m_curr_row->GetOffset()) {
UnwindPlan::Row *newrow = new UnwindPlan::Row;
*newrow = *it->second.first;
m_curr_row.reset(newrow);
m_register_values = it->second.second;
}
m_inst_emulator_ap->SetInstruction(inst->GetOpcode(),
inst->GetAddress(), nullptr);
if (last_condition !=
m_inst_emulator_ap->GetInstructionCondition()) {
if (m_inst_emulator_ap->GetInstructionCondition() !=
EmulateInstruction::UnconditionalCondition &&
saved_unwind_states.count(current_offset) == 0) {
// If we don't have a saved row for the current offset then save
// our
// current state because we will have to restore it after the
// conditional block.
auto new_row =
std::make_shared<UnwindPlan::Row>(*m_curr_row.get());
saved_unwind_states.insert(
{current_offset, {new_row, m_register_values}});
}
// If the last instruction was conditional with a different
// condition
// then the then current condition then restore the condition.
if (last_condition !=
EmulateInstruction::UnconditionalCondition) {
const auto &saved_state =
saved_unwind_states.at(condition_block_start_offset);
m_curr_row =
std::make_shared<UnwindPlan::Row>(*saved_state.first);
m_curr_row->SetOffset(current_offset);
m_register_values = saved_state.second;
bool replace_existing =
true; // The last instruction might already
// created a row for this offset and
// we want to overwrite it.
unwind_plan.InsertRow(
std::make_shared<UnwindPlan::Row>(*m_curr_row),
replace_existing);
}
// We are starting a new conditional block at the catual offset
condition_block_start_offset = current_offset;
}
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, NULL, NULL, NULL, &format, 0);
log->PutString(strm.GetString());
}
last_condition = m_inst_emulator_ap->GetInstructionCondition();
m_inst_emulator_ap->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)) {
auto newrow =
std::make_shared<UnwindPlan::Row>(*m_curr_row.get());
newrow->SetOffset(current_offset + m_forward_branch_offset);
saved_unwind_states.insert(
{current_offset + m_forward_branch_offset,
{newrow, m_register_values}});
unwind_plan.InsertRow(newrow);
}
// 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
// currennt address
if (saved_unwind_states.count(
current_offset + inst->GetOpcode().GetByteSize()) == 0) {
m_curr_row->SetOffset(current_offset +
inst->GetOpcode().GetByteSize());
unwind_plan.InsertRow(m_curr_row);
saved_unwind_states.insert(
{current_offset + inst->GetOpcode().GetByteSize(),
{m_curr_row, m_register_values}});
// Allocate a new Row for m_curr_row, copy the current state
// into it
UnwindPlan::Row *newrow = new UnwindPlan::Row;
*newrow = *m_curr_row.get();
m_curr_row.reset(newrow);
}
}
}
}
}
}
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;
}
return false;
}
bool
UnwindAssemblyInstEmulation::GetNonCallSiteUnwindPlanFromAssembly (AddressRange& range,
Thread& thread,
UnwindPlan& unwind_plan)
{
if (range.GetByteSize() > 0 &&
range.GetBaseAddress().IsValid() &&
m_inst_emulator_ap.get())
{
// The instruction emulation subclass setup the unwind plan for the
// first instruction.
m_inst_emulator_ap->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;
ExecutionContext exe_ctx;
thread.CalculateExecutionContext(exe_ctx);
const bool prefer_file_cache = true;
DisassemblerSP disasm_sp (Disassembler::DisassembleRange (m_arch,
NULL,
NULL,
exe_ctx,
range,
prefer_file_cache));
Log *log(GetLogIfAllCategoriesSet (LIBLLDB_LOG_UNWIND));
if (disasm_sp)
{
m_range_ptr = ⦥
m_thread_ptr = &thread;
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;
m_inst_emulator_ap->GetRegisterInfo (unwind_plan.GetRegisterKind(),
unwind_plan.GetInitialCFARegister(),
m_cfa_reg_info);
m_fp_is_cfa = false;
m_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_cfa_reg_info.byte_size);
SetRegisterValue (m_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 addr_t base_addr = inst->GetAddress().GetFileAddress();
// Make a copy of the current instruction Row and save it in m_curr_row
// so we can add updates as we process the instructions.
UnwindPlan::RowSP last_row = unwind_plan.GetLastRow();
UnwindPlan::Row *newrow = new UnwindPlan::Row;
if (last_row.get())
*newrow = *last_row.get();
m_curr_row.reset(newrow);
// Once we've seen the initial prologue instructions complete, save a
// copy of the CFI at that point into prologue_completed_row for possible
// use later.
int instructions_since_last_prologue_insn = 0; // # of insns since last CFI was update
bool reinstate_prologue_next_instruction = false; // Next iteration, re-install the prologue row of CFI
bool last_instruction_restored_return_addr_reg = false; // re-install the prologue row of CFI if the next instruction is a branch immediate
bool return_address_register_has_been_saved = false; // if we've seen the ra register get saved yet
UnwindPlan::RowSP prologue_completed_row; // copy of prologue row of CFI
// cache the pc register number (in whatever register numbering this UnwindPlan uses) for
// quick reference during instruction parsing.
uint32_t pc_reg_num = LLDB_INVALID_REGNUM;
RegisterInfo pc_reg_info;
if (m_inst_emulator_ap->GetRegisterInfo (eRegisterKindGeneric, LLDB_REGNUM_GENERIC_PC, pc_reg_info))
pc_reg_num = pc_reg_info.kinds[unwind_plan.GetRegisterKind()];
else
pc_reg_num = LLDB_INVALID_REGNUM;
// cache the return address register number (in whatever register numbering this UnwindPlan uses) for
// quick reference during instruction parsing.
uint32_t ra_reg_num = LLDB_INVALID_REGNUM;
RegisterInfo ra_reg_info;
if (m_inst_emulator_ap->GetRegisterInfo (eRegisterKindGeneric, LLDB_REGNUM_GENERIC_RA, ra_reg_info))
ra_reg_num = ra_reg_info.kinds[unwind_plan.GetRegisterKind()];
else
ra_reg_num = LLDB_INVALID_REGNUM;
for (size_t idx=0; idx<num_instructions; ++idx)
{
m_curr_row_modified = false;
m_curr_insn_restored_a_register = false;
inst = inst_list.GetInstructionAtIndex (idx).get();
if (inst)
{
if (log && log->GetVerbose ())
{
StreamString strm;
inst->Dump(&strm, inst_list.GetMaxOpcocdeByteSize (), show_address, show_bytes, NULL);
log->PutCString (strm.GetData());
}
m_inst_emulator_ap->SetInstruction (inst->GetOpcode(),
inst->GetAddress(),
exe_ctx.GetTargetPtr());
m_inst_emulator_ap->EvaluateInstruction (eEmulateInstructionOptionIgnoreConditions);
// Were there any changes to the CFI while evaluating this instruction?
if (m_curr_row_modified)
{
reinstate_prologue_next_instruction = false;
m_curr_row->SetOffset (inst->GetAddress().GetFileAddress() + inst->GetOpcode().GetByteSize() - base_addr);
// Append the new row
unwind_plan.AppendRow (m_curr_row);
// Allocate a new Row for m_curr_row, copy the current state into it
UnwindPlan::Row *newrow = new UnwindPlan::Row;
*newrow = *m_curr_row.get();
m_curr_row.reset(newrow);
// If m_curr_insn_restored_a_register == true, we're looking at an epilogue instruction.
// Set instructions_since_last_prologue_insn to a very high number so we don't append
// any of these epilogue instructions to our prologue_complete row.
if (m_curr_insn_restored_a_register == false && instructions_since_last_prologue_insn < 8)
instructions_since_last_prologue_insn = 0;
else
instructions_since_last_prologue_insn = 99;
UnwindPlan::Row::RegisterLocation pc_regloc;
UnwindPlan::Row::RegisterLocation ra_regloc;
// While parsing the instructions of this function, if we've ever
// seen the return address register (aka lr on arm) in a non-IsSame() state,
// it has been saved on the stack. If it's ever back to IsSame(), we've
// executed an epilogue.
if (ra_reg_num != LLDB_INVALID_REGNUM
&& m_curr_row->GetRegisterInfo (ra_reg_num, ra_regloc)
&& !ra_regloc.IsSame())
{
return_address_register_has_been_saved = true;
}
// If the caller's pc is "same", we've just executed an epilogue and we return to the caller
// after this instruction completes executing.
// If there are any instructions past this, there must have been flow control over this
// epilogue so we'll reinstate the original prologue setup instructions.
if (prologue_completed_row.get()
&& pc_reg_num != LLDB_INVALID_REGNUM
&& m_curr_row->GetRegisterInfo (pc_reg_num, pc_regloc)
&& pc_regloc.IsSame())
{
if (log && log->GetVerbose())
log->Printf("UnwindAssemblyInstEmulation::GetNonCallSiteUnwindPlanFromAssembly -- pc is <same>, restore prologue instructions.");
reinstate_prologue_next_instruction = true;
}
else if (prologue_completed_row.get()
&& return_address_register_has_been_saved
&& ra_reg_num != LLDB_INVALID_REGNUM
&& m_curr_row->GetRegisterInfo (ra_reg_num, ra_regloc)
&& ra_regloc.IsSame())
{
if (log && log->GetVerbose())
log->Printf("UnwindAssemblyInstEmulation::GetNonCallSiteUnwindPlanFromAssembly -- lr is <same>, restore prologue instruction if the next instruction is a branch immediate.");
last_instruction_restored_return_addr_reg = true;
}
}
else
{
// If the previous instruction was a return-to-caller (epilogue), and we're still executing
// instructions in this function, there must be a code path that jumps over that epilogue.
// Also detect the case where we epilogue & branch imm to another function (tail-call opt)
// instead of a normal pop lr-into-pc exit.
// Reinstate the frame setup from the prologue.
if (reinstate_prologue_next_instruction
|| (m_curr_insn_is_branch_immediate && last_instruction_restored_return_addr_reg))
{
if (log && log->GetVerbose())
log->Printf("UnwindAssemblyInstEmulation::GetNonCallSiteUnwindPlanFromAssembly -- Reinstating prologue instruction set");
UnwindPlan::Row *newrow = new UnwindPlan::Row;
*newrow = *prologue_completed_row.get();
m_curr_row.reset(newrow);
m_curr_row->SetOffset (inst->GetAddress().GetFileAddress() + inst->GetOpcode().GetByteSize() - base_addr);
unwind_plan.AppendRow(m_curr_row);
newrow = new UnwindPlan::Row;
*newrow = *m_curr_row.get();
m_curr_row.reset(newrow);
reinstate_prologue_next_instruction = false;
last_instruction_restored_return_addr_reg = false;
m_curr_insn_is_branch_immediate = false;
}
// clear both of these if either one wasn't set
if (last_instruction_restored_return_addr_reg)
{
last_instruction_restored_return_addr_reg = false;
}
if (m_curr_insn_is_branch_immediate)
{
m_curr_insn_is_branch_immediate = false;
}
// Stop updating the prologue instructions if we've seen 8 non-prologue instructions
// in a row.
if (instructions_since_last_prologue_insn++ < 8)
{
UnwindPlan::Row *newrow = new UnwindPlan::Row;
*newrow = *m_curr_row.get();
prologue_completed_row.reset(newrow);
if (log && log->GetVerbose())
log->Printf("UnwindAssemblyInstEmulation::GetNonCallSiteUnwindPlanFromAssembly -- saving a copy of the current row as the prologue row.");
}
}
}
}
}
// FIXME: The DisassemblerLLVMC has a reference cycle and won't go away if it has any active instructions.
// I'll fix that but for now, just clear the list and it will go away nicely.
disasm_sp->GetInstructionList().Clear();
}
if (log && log->GetVerbose ())
{
StreamString strm;
lldb::addr_t base_addr = range.GetBaseAddress().GetLoadAddress(thread.CalculateTarget().get());
strm.Printf ("Resulting unwind rows for [0x%" PRIx64 " - 0x%" PRIx64 "):", base_addr, base_addr + range.GetByteSize());
unwind_plan.Dump(strm, &thread, base_addr);
log->PutCString (strm.GetData());
}
return unwind_plan.GetRowCount() > 0;
}
return false;
}