UnwindPlan.cpp

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//===-- UnwindPlan.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/Symbol/UnwindPlan.h"
 
#include "lldb/Target/Process.h"
#include "lldb/Target/RegisterContext.h"
#include "lldb/Target/Target.h"
#include "lldb/Target/Thread.h"
#include "lldb/Utility/ConstString.h"
#include "lldb/Utility/LLDBLog.h"
#include "lldb/Utility/Log.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/DebugInfo/DIContext.h"
#include "llvm/DebugInfo/DWARF/DWARFExpressionPrinter.h"
#include "llvm/DebugInfo/DWARF/LowLevel/DWARFExpression.h"
#include <optional>
 
using namespace lldb;
using namespace lldb_private;
 
bool UnwindPlan::Row::AbstractRegisterLocation::operator==(
    const UnwindPlan::Row::AbstractRegisterLocation &rhs) const {
  if (m_type == rhs.m_type) {
    switch (m_type) {
    case unspecified:
    case undefined:
    case same:
      return true;
 
    case atCFAPlusOffset:
    case isCFAPlusOffset:
    case atAFAPlusOffset:
    case isAFAPlusOffset:
      return m_location.offset == rhs.m_location.offset;
 
    case inOtherRegister:
      return m_location.reg_num == rhs.m_location.reg_num;
 
    case atDWARFExpression:
    case isDWARFExpression:
      if (m_location.expr.length == rhs.m_location.expr.length)
        return !memcmp(m_location.expr.opcodes, rhs.m_location.expr.opcodes,
                       m_location.expr.length);
      break;
    case isConstant:
      return m_location.constant_value == rhs.m_location.constant_value;
    }
  }
  return false;
}
 
// This function doesn't copy the dwarf expression bytes; they must remain in
// allocated memory for the lifespan of this UnwindPlan object.
void UnwindPlan::Row::AbstractRegisterLocation::SetAtDWARFExpression(
    const uint8_t *opcodes, uint32_t len) {
  m_type = atDWARFExpression;
  m_location.expr.opcodes = opcodes;
  m_location.expr.length = len;
}
 
// This function doesn't copy the dwarf expression bytes; they must remain in
// allocated memory for the lifespan of this UnwindPlan object.
void UnwindPlan::Row::AbstractRegisterLocation::SetIsDWARFExpression(
    const uint8_t *opcodes, uint32_t len) {
  m_type = isDWARFExpression;
  m_location.expr.opcodes = opcodes;
  m_location.expr.length = len;
}
 
static std::optional<std::pair<lldb::ByteOrder, uint32_t>>
GetByteOrderAndAddrSize(Thread *thread) {
  if (!thread)
    return std::nullopt;
  ProcessSP process_sp = thread->GetProcess();
  if (!process_sp)
    return std::nullopt;
  ArchSpec arch = process_sp->GetTarget().GetArchitecture();
  return std::make_pair(arch.GetByteOrder(), arch.GetAddressByteSize());
}
 
static void DumpDWARFExpr(Stream &s, llvm::ArrayRef<uint8_t> expr, Thread *thread) {
  if (auto order_and_width = GetByteOrderAndAddrSize(thread)) {
    llvm::DataExtractor data(expr, order_and_width->first == eByteOrderLittle,
                             order_and_width->second);
    llvm::DWARFExpression E(data, order_and_width->second,
                            llvm::dwarf::DWARF32);
    printDwarfExpression(&E, s.AsRawOstream(), llvm::DIDumpOptions(), nullptr);
  } else
    s.PutCString("dwarf-expr");
}
 
void UnwindPlan::Row::AbstractRegisterLocation::Dump(
    Stream &s, const UnwindPlan *unwind_plan, const UnwindPlan::Row *row,
    Thread *thread, bool verbose) const {
  switch (m_type) {
  case unspecified:
    if (verbose)
      s.PutCString("=<unspec>");
    else
      s.PutCString("=!");
    break;
  case undefined:
    if (verbose)
      s.PutCString("=<undef>");
    else
      s.PutCString("=?");
    break;
  case same:
    s.PutCString("= <same>");
    break;
 
  case atCFAPlusOffset:
  case isCFAPlusOffset: {
    s.PutChar('=');
    if (m_type == atCFAPlusOffset)
      s.PutChar('[');
    s.Printf("CFA%+d", m_location.offset);
    if (m_type == atCFAPlusOffset)
      s.PutChar(']');
  } break;
 
  case atAFAPlusOffset:
  case isAFAPlusOffset: {
    s.PutChar('=');
    if (m_type == atAFAPlusOffset)
      s.PutChar('[');
    s.Printf("AFA%+d", m_location.offset);
    if (m_type == atAFAPlusOffset)
      s.PutChar(']');
  } break;
 
  case inOtherRegister: {
    const RegisterInfo *other_reg_info = nullptr;
    if (unwind_plan)
      other_reg_info = unwind_plan->GetRegisterInfo(thread, m_location.reg_num);
    if (other_reg_info)
      s.Printf("=%s", other_reg_info->name);
    else
      s.Printf("=reg(%u)", m_location.reg_num);
  } break;
 
  case atDWARFExpression:
  case isDWARFExpression: {
    s.PutChar('=');
    if (m_type == atDWARFExpression)
      s.PutChar('[');
    DumpDWARFExpr(
        s, llvm::ArrayRef(m_location.expr.opcodes, m_location.expr.length),
        thread);
    if (m_type == atDWARFExpression)
      s.PutChar(']');
  } break;
  case isConstant:
    s.Printf("=0x%" PRIx64, m_location.constant_value);
    break;
  }
}
 
static void DumpRegisterName(Stream &s, const UnwindPlan *unwind_plan,
                             Thread *thread, uint32_t reg_num) {
  const RegisterInfo *reg_info = unwind_plan->GetRegisterInfo(thread, reg_num);
  if (reg_info)
    s.PutCString(reg_info->name);
  else
    s.Printf("reg(%u)", reg_num);
}
 
bool UnwindPlan::Row::FAValue::
operator==(const UnwindPlan::Row::FAValue &rhs) const {
  if (m_type == rhs.m_type) {
    switch (m_type) {
    case unspecified:
    case isRaSearch:
      return m_value.ra_search_offset == rhs.m_value.ra_search_offset;
 
    case isRegisterPlusOffset:
      return m_value.reg.offset == rhs.m_value.reg.offset;
 
    case isRegisterDereferenced:
      return m_value.reg.reg_num == rhs.m_value.reg.reg_num;
 
    case isDWARFExpression:
      if (m_value.expr.length == rhs.m_value.expr.length)
        return !memcmp(m_value.expr.opcodes, rhs.m_value.expr.opcodes,
                       m_value.expr.length);
      break;
    case isConstant:
      return m_value.constant == rhs.m_value.constant;
    }
  }
  return false;
}
 
void UnwindPlan::Row::FAValue::Dump(Stream &s, const UnwindPlan *unwind_plan,
                                     Thread *thread) const {
  switch (m_type) {
  case isRegisterPlusOffset:
    DumpRegisterName(s, unwind_plan, thread, m_value.reg.reg_num);
    s.Printf("%+3d", m_value.reg.offset);
    break;
  case isRegisterDereferenced:
    s.PutChar('[');
    DumpRegisterName(s, unwind_plan, thread, m_value.reg.reg_num);
    s.PutChar(']');
    break;
  case isDWARFExpression:
    DumpDWARFExpr(s, llvm::ArrayRef(m_value.expr.opcodes, m_value.expr.length),
                  thread);
    break;
  case unspecified:
    s.PutCString("unspecified");
    break;
  case isRaSearch:
    s.Printf("RaSearch@SP%+d", m_value.ra_search_offset);
    break;
  case isConstant:
    s.Printf("0x%" PRIx64, m_value.constant);
  }
}
 
void UnwindPlan::Row::Clear() {
  m_cfa_value.SetUnspecified();
  m_afa_value.SetUnspecified();
  m_offset = 0;
  m_unspecified_registers_are_undefined = false;
  m_register_locations.clear();
}
 
void UnwindPlan::Row::Dump(Stream &s, const UnwindPlan *unwind_plan,
                           Thread *thread, addr_t base_addr) const {
  if (base_addr != LLDB_INVALID_ADDRESS)
    s.Printf("0x%16.16" PRIx64 ": CFA=", base_addr + GetOffset());
  else
    s.Printf("%4" PRId64 ": CFA=", GetOffset());
 
  m_cfa_value.Dump(s, unwind_plan, thread);
 
  if (!m_afa_value.IsUnspecified()) {
    s.Printf(" AFA=");
    m_afa_value.Dump(s, unwind_plan, thread);
  }
 
  s.Printf(" => ");
  for (collection::const_iterator idx = m_register_locations.begin();
       idx != m_register_locations.end(); ++idx) {
    DumpRegisterName(s, unwind_plan, thread, idx->first);
    const bool verbose = false;
    idx->second.Dump(s, unwind_plan, this, thread, verbose);
    s.PutChar(' ');
  }
}
 
UnwindPlan::Row::Row() : m_cfa_value(), m_afa_value(), m_register_locations() {}
 
bool UnwindPlan::Row::GetRegisterInfo(
    uint32_t reg_num,
    UnwindPlan::Row::AbstractRegisterLocation &register_location) const {
  collection::const_iterator pos = m_register_locations.find(reg_num);
  if (pos != m_register_locations.end()) {
    register_location = pos->second;
    return true;
  }
  if (m_unspecified_registers_are_undefined) {
    register_location.SetUndefined();
    return true;
  }
  return false;
}
 
void UnwindPlan::Row::RemoveRegisterInfo(uint32_t reg_num) {
  collection::const_iterator pos = m_register_locations.find(reg_num);
  if (pos != m_register_locations.end()) {
    m_register_locations.erase(pos);
  }
}
 
void UnwindPlan::Row::SetRegisterInfo(
    uint32_t reg_num,
    const UnwindPlan::Row::AbstractRegisterLocation register_location) {
  m_register_locations[reg_num] = register_location;
}
 
bool UnwindPlan::Row::SetRegisterLocationToAtCFAPlusOffset(uint32_t reg_num,
                                                           int32_t offset,
                                                           bool can_replace) {
  if (!can_replace &&
      m_register_locations.find(reg_num) != m_register_locations.end())
    return false;
  AbstractRegisterLocation reg_loc;
  reg_loc.SetAtCFAPlusOffset(offset);
  m_register_locations[reg_num] = reg_loc;
  return true;
}
 
bool UnwindPlan::Row::SetRegisterLocationToIsCFAPlusOffset(uint32_t reg_num,
                                                           int32_t offset,
                                                           bool can_replace) {
  if (!can_replace &&
      m_register_locations.find(reg_num) != m_register_locations.end())
    return false;
  AbstractRegisterLocation reg_loc;
  reg_loc.SetIsCFAPlusOffset(offset);
  m_register_locations[reg_num] = reg_loc;
  return true;
}
 
bool UnwindPlan::Row::SetRegisterLocationToUndefined(
    uint32_t reg_num, bool can_replace, bool can_replace_only_if_unspecified) {
  collection::iterator pos = m_register_locations.find(reg_num);
  collection::iterator end = m_register_locations.end();
 
  if (pos != end) {
    if (!can_replace)
      return false;
    if (can_replace_only_if_unspecified && !pos->second.IsUnspecified())
      return false;
  }
  AbstractRegisterLocation reg_loc;
  reg_loc.SetUndefined();
  m_register_locations[reg_num] = reg_loc;
  return true;
}
 
bool UnwindPlan::Row::SetRegisterLocationToUnspecified(uint32_t reg_num,
                                                       bool can_replace) {
  if (!can_replace &&
      m_register_locations.find(reg_num) != m_register_locations.end())
    return false;
  AbstractRegisterLocation reg_loc;
  reg_loc.SetUnspecified();
  m_register_locations[reg_num] = reg_loc;
  return true;
}
 
bool UnwindPlan::Row::SetRegisterLocationToRegister(uint32_t reg_num,
                                                    uint32_t other_reg_num,
                                                    bool can_replace) {
  if (!can_replace &&
      m_register_locations.find(reg_num) != m_register_locations.end())
    return false;
  AbstractRegisterLocation reg_loc;
  reg_loc.SetInRegister(other_reg_num);
  m_register_locations[reg_num] = reg_loc;
  return true;
}
 
bool UnwindPlan::Row::SetRegisterLocationToSame(uint32_t reg_num,
                                                bool must_replace) {
  if (must_replace &&
      m_register_locations.find(reg_num) == m_register_locations.end())
    return false;
  AbstractRegisterLocation reg_loc;
  reg_loc.SetSame();
  m_register_locations[reg_num] = reg_loc;
  return true;
}
 
bool UnwindPlan::Row::SetRegisterLocationToIsDWARFExpression(
    uint32_t reg_num, const uint8_t *opcodes, uint32_t len, bool can_replace) {
  if (!can_replace &&
      m_register_locations.find(reg_num) != m_register_locations.end())
    return false;
  AbstractRegisterLocation reg_loc;
  reg_loc.SetIsDWARFExpression(opcodes, len);
  m_register_locations[reg_num] = reg_loc;
  return true;
}
 
bool UnwindPlan::Row::SetRegisterLocationToIsConstant(uint32_t reg_num,
                                                      uint64_t constant,
                                                      bool can_replace) {
  if (!can_replace &&
      m_register_locations.find(reg_num) != m_register_locations.end())
    return false;
  AbstractRegisterLocation reg_loc;
  reg_loc.SetIsConstant(constant);
  m_register_locations[reg_num] = reg_loc;
  return true;
}
 
bool UnwindPlan::Row::operator==(const UnwindPlan::Row &rhs) const {
  return m_offset == rhs.m_offset && m_cfa_value == rhs.m_cfa_value &&
         m_afa_value == rhs.m_afa_value &&
         m_unspecified_registers_are_undefined ==
             rhs.m_unspecified_registers_are_undefined &&
         m_register_locations == rhs.m_register_locations;
}
 
void UnwindPlan::AppendRow(Row row) {
  if (m_row_list.empty() || m_row_list.back().GetOffset() != row.GetOffset())
    m_row_list.push_back(std::move(row));
  else
    m_row_list.back() = std::move(row);
}
 
struct RowLess {
  bool operator()(int64_t a, const UnwindPlan::Row &b) const {
    return a < b.GetOffset();
  }
  bool operator()(const UnwindPlan::Row &a, int64_t b) const {
    return a.GetOffset() < b;
  }
};
 
void UnwindPlan::InsertRow(Row row, bool replace_existing) {
  auto it = llvm::lower_bound(m_row_list, row.GetOffset(), RowLess());
  if (it == m_row_list.end() || it->GetOffset() > row.GetOffset())
    m_row_list.insert(it, std::move(row));
  else {
    assert(it->GetOffset() == row.GetOffset());
    if (replace_existing)
      *it = std::move(row);
  }
}
 
const UnwindPlan::Row *
UnwindPlan::GetRowForFunctionOffset(std::optional<int64_t> offset) const {
  auto it = offset ? llvm::upper_bound(m_row_list, *offset, RowLess())
                   : m_row_list.end();
  if (it == m_row_list.begin())
    return nullptr;
  // upper_bound returns the row strictly greater than our desired offset, which
  // means that the row before it is a match.
  return &*std::prev(it);
}
 
bool UnwindPlan::IsValidRowIndex(uint32_t idx) const {
  return idx < m_row_list.size();
}
 
const UnwindPlan::Row *UnwindPlan::GetRowAtIndex(uint32_t idx) const {
  if (idx < m_row_list.size())
    return &m_row_list[idx];
  LLDB_LOG(GetLog(LLDBLog::Unwind),
           "error: UnwindPlan::GetRowAtIndex(idx = {0}) invalid index "
           "(number rows is {1})",
           idx, m_row_list.size());
  return nullptr;
}
 
const UnwindPlan::Row *UnwindPlan::GetLastRow() const {
  if (m_row_list.empty()) {
    LLDB_LOG(GetLog(LLDBLog::Unwind),
             "UnwindPlan::GetLastRow() when rows are empty");
    return nullptr;
  }
  return &m_row_list.back();
}
 
bool UnwindPlan::PlanValidAtAddress(Address addr) const {
  // If this UnwindPlan has no rows, it is an invalid UnwindPlan.
  if (GetRowCount() == 0) {
    Log *log = GetLog(LLDBLog::Unwind);
    if (log) {
      StreamString s;
      if (addr.Dump(&s, nullptr, Address::DumpStyleSectionNameOffset)) {
        LLDB_LOGF(log,
                  "UnwindPlan is invalid -- no unwind rows for UnwindPlan "
                  "'%s' at address %s",
                  m_source_name.GetCString(), s.GetData());
      } else {
        LLDB_LOGF(log,
                  "UnwindPlan is invalid -- no unwind rows for UnwindPlan '%s'",
                  m_source_name.GetCString());
      }
    }
    return false;
  }
 
  // If the 0th Row of unwind instructions is missing, or if it doesn't provide
  // a register to use to find the Canonical Frame Address, this is not a valid
  // UnwindPlan.
  const Row *row0 = GetRowAtIndex(0);
  if (!row0 ||
      row0->GetCFAValue().GetValueType() == Row::FAValue::unspecified) {
    Log *log = GetLog(LLDBLog::Unwind);
    if (log) {
      StreamString s;
      if (addr.Dump(&s, nullptr, Address::DumpStyleSectionNameOffset)) {
        LLDB_LOGF(log,
                  "UnwindPlan is invalid -- no CFA register defined in row 0 "
                  "for UnwindPlan '%s' at address %s",
                  m_source_name.GetCString(), s.GetData());
      } else {
        LLDB_LOGF(log,
                  "UnwindPlan is invalid -- no CFA register defined in row 0 "
                  "for UnwindPlan '%s'",
                  m_source_name.GetCString());
      }
    }
    return false;
  }
 
  if (m_plan_valid_ranges.empty())
    return true;
 
  if (!addr.IsValid())
    return true;
 
  return llvm::any_of(m_plan_valid_ranges, [&](const AddressRange &range) {
    return range.ContainsFileAddress(addr);
  });
}
 
void UnwindPlan::Dump(Stream &s, Thread *thread, lldb::addr_t base_addr) const {
  if (!m_source_name.IsEmpty()) {
    s.Printf("This UnwindPlan originally sourced from %s\n",
             m_source_name.GetCString());
  }
  s.Printf("This UnwindPlan is sourced from the compiler: ");
  switch (m_plan_is_sourced_from_compiler) {
  case eLazyBoolYes:
    s.Printf("yes.\n");
    break;
  case eLazyBoolNo:
    s.Printf("no.\n");
    break;
  case eLazyBoolCalculate:
    s.Printf("not specified.\n");
    break;
  }
  s.Printf("This UnwindPlan is valid at all instruction locations: ");
  switch (m_plan_is_valid_at_all_instruction_locations) {
  case eLazyBoolYes:
    s.Printf("yes.\n");
    break;
  case eLazyBoolNo:
    s.Printf("no.\n");
    break;
  case eLazyBoolCalculate:
    s.Printf("not specified.\n");
    break;
  }
  s.Printf("This UnwindPlan is for a trap handler function: ");
  switch (m_plan_is_for_signal_trap) {
  case eLazyBoolYes:
    s.Printf("yes.\n");
    break;
  case eLazyBoolNo:
    s.Printf("no.\n");
    break;
  case eLazyBoolCalculate:
    s.Printf("not specified.\n");
    break;
  }
  if (!m_plan_valid_ranges.empty()) {
    s.PutCString("Address range of this UnwindPlan: ");
    TargetSP target_sp(thread->CalculateTarget());
    for (const AddressRange &range : m_plan_valid_ranges)
      range.Dump(&s, target_sp.get(), Address::DumpStyleSectionNameOffset);
    s.EOL();
  }
  for (const auto &[index, row] : llvm::enumerate(m_row_list)) {
    s.Format("row[{0}]: ", index);
    row.Dump(s, this, thread, base_addr);
    s << "\n";
  }
}
 
void UnwindPlan::SetSourceName(const char *source) {
  m_source_name = ConstString(source);
}
 
ConstString UnwindPlan::GetSourceName() const { return m_source_name; }
 
const RegisterInfo *UnwindPlan::GetRegisterInfo(Thread *thread,
                                                uint32_t unwind_reg) const {
  if (thread) {
    RegisterContext *reg_ctx = thread->GetRegisterContext().get();
    if (reg_ctx) {
      uint32_t reg;
      if (m_register_kind == eRegisterKindLLDB)
        reg = unwind_reg;
      else
        reg = reg_ctx->ConvertRegisterKindToRegisterNumber(m_register_kind,
                                                           unwind_reg);
      if (reg != LLDB_INVALID_REGNUM)
        return reg_ctx->GetRegisterInfoAtIndex(reg);
    }
  }
  return nullptr;
}