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//===-- UnwindAssemblyInstEmulation.cpp --------------------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "UnwindAssemblyInstEmulation.h"
#include "lldb/Core/Address.h"
#include "lldb/Core/ArchSpec.h"
#include "lldb/Core/DataBufferHeap.h"
#include "lldb/Core/DataExtractor.h"
#include "lldb/Core/Disassembler.h"
#include "lldb/Core/Error.h"
#include "lldb/Core/Log.h"
#include "lldb/Core/PluginManager.h"
#include "lldb/Core/StreamString.h"
#include "lldb/Target/ExecutionContext.h"
#include "lldb/Target/Process.h"
#include "lldb/Target/Thread.h"
#include "lldb/Target/Target.h"
using namespace lldb;
using namespace lldb_private;
//-----------------------------------------------------------------------------------------------
// UnwindAssemblyInstEmulation method definitions
//-----------------------------------------------------------------------------------------------
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);
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 addresss 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 evern 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;
}
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<EmulateInstruction> inst_emulator_ap (EmulateInstruction::FindPlugin (arch, eInstructionTypePrologueEpilogue, NULL));
// Make sure that all prologue instructions are handled
if (inst_emulator_ap.get())
return new UnwindAssemblyInstEmulation (arch, inst_emulator_ap.release());
return NULL;
}
//------------------------------------------------------------------
// PluginInterface protocol in UnwindAssemblyParser_x86
//------------------------------------------------------------------
ConstString
UnwindAssemblyInstEmulation::GetPluginName()
{
return GetPluginNameStatic();
}
uint32_t
UnwindAssemblyInstEmulation::GetPluginVersion()
{
return 1;
}
void
UnwindAssemblyInstEmulation::Initialize()
{
PluginManager::RegisterPlugin (GetPluginNameStatic(),
GetPluginDescriptionStatic(),
CreateInstance);
}
void
UnwindAssemblyInstEmulation::Terminate()
{
PluginManager::UnregisterPlugin (CreateInstance);
}
ConstString
UnwindAssemblyInstEmulation::GetPluginNameStatic()
{
static ConstString g_name("inst-emulation");
return g_name;
}
const char *
UnwindAssemblyInstEmulation::GetPluginDescriptionStatic()
{
return "Instruction emulation based unwind information.";
}
uint64_t
UnwindAssemblyInstEmulation::MakeRegisterKindValuePair (const RegisterInfo &reg_info)
{
uint32_t reg_kind, reg_num;
if (EmulateInstruction::GetBestRegisterKindAndNumber (&reg_info, reg_kind, reg_num))
return (uint64_t)reg_kind << 24 | reg_num;
return 0ull;
}
void
UnwindAssemblyInstEmulation::SetRegisterValue (const RegisterInfo &reg_info, const RegisterValue &reg_value)
{
m_register_values[MakeRegisterKindValuePair (reg_info)] = reg_value;
}
bool
UnwindAssemblyInstEmulation::GetRegisterValue (const RegisterInfo &reg_info, RegisterValue &reg_value)
{
const uint64_t reg_id = MakeRegisterKindValuePair (reg_info);
RegisterValueMap::const_iterator pos = m_register_values.find(reg_id);
if (pos != m_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(GetLogIfAllCategoriesSet (LIBLLDB_LOG_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->PutCString (strm.GetData ());
}
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(GetLogIfAllCategoriesSet (LIBLLDB_LOG_UNWIND));
if (log && log->GetVerbose ())
{
StreamString strm;
strm.PutCString ("UnwindAssemblyInstEmulation::WriteMemory (");
data.Dump(&strm, 0, eFormatBytes, 1, dst_len, UINT32_MAX, addr, 0, 0);
strm.PutCString (", context = ");
context.Dump(strm, instruction);
log->PutCString (strm.GetData());
}
const bool can_replace = true;
const bool cant_replace = false;
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;
bool is_return_address_reg = false;
const uint32_t unwind_reg_kind = m_unwind_plan_ptr->GetRegisterKind();
if (context.info_type == EmulateInstruction::eInfoTypeRegisterToRegisterPlusOffset)
{
reg_num = context.info.RegisterToRegisterPlusOffset.data_reg.kinds[unwind_reg_kind];
if (context.info.RegisterToRegisterPlusOffset.data_reg.kinds[eRegisterKindGeneric] == LLDB_REGNUM_GENERIC_RA)
is_return_address_reg = true;
}
else
{
assert (!"unhandled case, add code to handle this!");
}
if (reg_num != LLDB_INVALID_REGNUM)
{
if (m_pushed_regs.find (reg_num) == m_pushed_regs.end())
{
m_pushed_regs[reg_num] = addr;
const int32_t offset = addr - m_initial_sp;
m_curr_row->SetRegisterLocationToAtCFAPlusOffset (reg_num, offset, cant_replace);
m_curr_row_modified = true;
if (is_return_address_reg)
{
// This push was pushing the return address register,
// so this is also how we will unwind the PC...
RegisterInfo pc_reg_info;
if (instruction->GetRegisterInfo (eRegisterKindGeneric, LLDB_REGNUM_GENERIC_PC, pc_reg_info))
{
uint32_t pc_reg_num = pc_reg_info.kinds[unwind_reg_kind];
if (pc_reg_num != LLDB_INVALID_REGNUM)
{
m_curr_row->SetRegisterLocationToAtCFAPlusOffset (pc_reg_num, offset, can_replace);
m_curr_row_modified = true;
}
}
}
}
}
}
break;
}
return dst_len;
}
bool
UnwindAssemblyInstEmulation::ReadRegister (EmulateInstruction *instruction,
void *baton,
const RegisterInfo *reg_info,
RegisterValue &reg_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 &reg_value)
{
bool synthetic = GetRegisterValue (*reg_info, reg_value);
Log *log(GetLogIfAllCategoriesSet (LIBLLDB_LOG_UNWIND));
if (log && log->GetVerbose ())
{
StreamString strm;
strm.Printf ("UnwindAssemblyInstEmulation::ReadRegister (name = \"%s\") => synthetic_value = %i, value = ", reg_info->name, synthetic);
reg_value.Dump(&strm, reg_info, false, false, eFormatDefault);
log->PutCString(strm.GetData());
}
return true;
}
bool
UnwindAssemblyInstEmulation::WriteRegister (EmulateInstruction *instruction,
void *baton,
const EmulateInstruction::Context &context,
const RegisterInfo *reg_info,
const RegisterValue &reg_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 &reg_value)
{
Log *log(GetLogIfAllCategoriesSet (LIBLLDB_LOG_UNWIND));
if (log && log->GetVerbose ())
{
StreamString strm;
strm.Printf ("UnwindAssemblyInstEmulation::WriteRegister (name = \"%s\", value = ", reg_info->name);
reg_value.Dump(&strm, reg_info, false, false, eFormatDefault);
strm.PutCString (", context = ");
context.Dump(strm, instruction);
log->PutCString(strm.GetData());
}
const bool must_replace = true;
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::eContextRegisterLoad:
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::eContextPushRegisterOnStack:
// {
// 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::eContextRelativeBranchImmediate:
{
{
m_curr_insn_is_branch_immediate = true;
}
}
break;
case EmulateInstruction::eContextPopRegisterOffStack:
{
const uint32_t reg_num = reg_info->kinds[m_unwind_plan_ptr->GetRegisterKind()];
if (reg_num != LLDB_INVALID_REGNUM)
{
m_curr_row->SetRegisterLocationToSame (reg_num, must_replace);
m_curr_row_modified = true;
m_curr_insn_restored_a_register = true;
}
}
break;
case EmulateInstruction::eContextSetFramePointer:
if (!m_fp_is_cfa)
{
m_fp_is_cfa = true;
m_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_curr_row->SetCFARegister(cfa_reg_num);
m_curr_row->SetCFAOffset(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_fp_is_cfa)
{
m_curr_row->SetCFAOffset (m_initial_sp - reg_value.GetAsUInt64());
m_curr_row_modified = true;
}
break;
}
return true;
}
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