lldb/source/Symbol/UnwindTable.cpp

   1 //===-- UnwindTable.cpp ---------------------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #include "lldb/Symbol/UnwindTable.h"
  10
  11 #include <cstdio>
  12 #include <optional>
  13
  14 #include "lldb/Core/Module.h"
  15 #include "lldb/Core/Section.h"
  16 #include "lldb/Symbol/ArmUnwindInfo.h"
  17 #include "lldb/Symbol/CallFrameInfo.h"
  18 #include "lldb/Symbol/CompactUnwindInfo.h"
  19 #include "lldb/Symbol/DWARFCallFrameInfo.h"
  20 #include "lldb/Symbol/FuncUnwinders.h"
  21 #include "lldb/Symbol/ObjectFile.h"
  22 #include "lldb/Symbol/SymbolContext.h"
  23 #include "lldb/Symbol/SymbolVendor.h"
  24
  25 // There is one UnwindTable object per ObjectFile. It contains a list of Unwind
  26 // objects -- one per function, populated lazily -- for the ObjectFile. Each
  27 // Unwind object has multiple UnwindPlans for different scenarios.
  28
  29 using namespace lldb;
  30 using namespace lldb_private;
  31
  32 UnwindTable::UnwindTable(Module &module)
  33     : m_module(module), m_unwinds(), m_initialized(false), m_mutex(),
  34       m_object_file_unwind_up(), m_eh_frame_up(), m_compact_unwind_up(),
  35       m_arm_unwind_up() {}
  36
  37 // We can't do some of this initialization when the ObjectFile is running its
  38 // ctor; delay doing it until needed for something.
  39
  40 void UnwindTable::Initialize() {
  41   if (m_initialized)
  42     return;
  43
  44   std::lock_guard<std::mutex> guard(m_mutex);
  45
  46   if (m_initialized) // check again once we've acquired the lock
  47     return;
  48   m_initialized = true;
  49   ObjectFile *object_file = m_module.GetObjectFile();
  50   if (!object_file)
  51     return;
  52
  53   m_object_file_unwind_up = object_file->CreateCallFrameInfo();
  54
  55   SectionList *sl = m_module.GetSectionList();
  56   if (!sl)
  57     return;
  58
  59   SectionSP sect = sl->FindSectionByType(eSectionTypeEHFrame, true);
  60   if (sect.get()) {
  61     m_eh_frame_up = std::make_unique<DWARFCallFrameInfo>(
  62         *object_file, sect, DWARFCallFrameInfo::EH);
  63   }
  64
  65   sect = sl->FindSectionByType(eSectionTypeDWARFDebugFrame, true);
  66   if (sect) {
  67     m_debug_frame_up = std::make_unique<DWARFCallFrameInfo>(
  68         *object_file, sect, DWARFCallFrameInfo::DWARF);
  69   }
  70
  71   sect = sl->FindSectionByType(eSectionTypeCompactUnwind, true);
  72   if (sect) {
  73     m_compact_unwind_up =
  74         std::make_unique<CompactUnwindInfo>(*object_file, sect);
  75   }
  76
  77   sect = sl->FindSectionByType(eSectionTypeARMexidx, true);
  78   if (sect) {
  79     SectionSP sect_extab = sl->FindSectionByType(eSectionTypeARMextab, true);
  80     if (sect_extab.get()) {
  81       m_arm_unwind_up =
  82           std::make_unique<ArmUnwindInfo>(*object_file, sect, sect_extab);
  83     }
  84   }
  85 }
  86
  87 UnwindTable::~UnwindTable() = default;
  88
  89 std::optional<AddressRange>
  90 UnwindTable::GetAddressRange(const Address &addr, const SymbolContext &sc) {
  91   AddressRange range;
  92
  93   // First check the unwind info from the object file plugin
  94   if (m_object_file_unwind_up &&
  95       m_object_file_unwind_up->GetAddressRange(addr, range))
  96     return range;
  97
  98   // Check the symbol context
  99   if (sc.GetAddressRange(eSymbolContextFunction | eSymbolContextSymbol, 0,
 100                          false, range) &&
 101       range.GetBaseAddress().IsValid())
 102     return range;
 103
 104   // Does the eh_frame unwind info has a function bounds for this addr?
 105   if (m_eh_frame_up && m_eh_frame_up->GetAddressRange(addr, range))
 106     return range;
 107
 108   // Try debug_frame as well
 109   if (m_debug_frame_up && m_debug_frame_up->GetAddressRange(addr, range))
 110     return range;
 111
 112   return std::nullopt;
 113 }
 114
 115 FuncUnwindersSP
 116 UnwindTable::GetFuncUnwindersContainingAddress(const Address &addr,
 117                                                SymbolContext &sc) {
 118   Initialize();
 119
 120   std::lock_guard<std::mutex> guard(m_mutex);
 121
 122   // There is an UnwindTable per object file, so we can safely use file handles
 123   addr_t file_addr = addr.GetFileAddress();
 124   iterator end = m_unwinds.end();
 125   iterator insert_pos = end;
 126   if (!m_unwinds.empty()) {
 127     insert_pos = m_unwinds.lower_bound(file_addr);
 128     iterator pos = insert_pos;
 129     if ((pos == m_unwinds.end()) ||
 130         (pos != m_unwinds.begin() &&
 131          pos->second->GetFunctionStartAddress() != addr))
 132       --pos;
 133
 134     if (pos->second->ContainsAddress(addr))
 135       return pos->second;
 136   }
 137
 138   auto range_or = GetAddressRange(addr, sc);
 139   if (!range_or)
 140     return nullptr;
 141
 142   FuncUnwindersSP func_unwinder_sp(new FuncUnwinders(*this, *range_or));
 143   m_unwinds.insert(insert_pos,
 144                    std::make_pair(range_or->GetBaseAddress().GetFileAddress(),
 145                                   func_unwinder_sp));
 146   return func_unwinder_sp;
 147 }
 148
 149 // Ignore any existing FuncUnwinders for this function, create a new one and
 150 // don't add it to the UnwindTable.  This is intended for use by target modules
 151 // show-unwind where we want to create new UnwindPlans, not re-use existing
 152 // ones.
 153 FuncUnwindersSP UnwindTable::GetUncachedFuncUnwindersContainingAddress(
 154     const Address &addr, const SymbolContext &sc) {
 155   Initialize();
 156
 157   auto range_or = GetAddressRange(addr, sc);
 158   if (!range_or)
 159     return nullptr;
 160
 161   return std::make_shared<FuncUnwinders>(*this, *range_or);
 162 }
 163
 164 void UnwindTable::Dump(Stream &s) {
 165   std::lock_guard<std::mutex> guard(m_mutex);
 166   s.Format("UnwindTable for '{0}':\n", m_module.GetFileSpec());
 167   const_iterator begin = m_unwinds.begin();
 168   const_iterator end = m_unwinds.end();
 169   for (const_iterator pos = begin; pos != end; ++pos) {
 170     s.Printf("[%u] 0x%16.16" PRIx64 "\n", (unsigned)std::distance(begin, pos),
 171              pos->first);
 172   }
 173   s.EOL();
 174 }
 175
 176 lldb_private::CallFrameInfo *UnwindTable::GetObjectFileUnwindInfo() {
 177   Initialize();
 178   return m_object_file_unwind_up.get();
 179 }
 180
 181 DWARFCallFrameInfo *UnwindTable::GetEHFrameInfo() {
 182   Initialize();
 183   return m_eh_frame_up.get();
 184 }
 185
 186 DWARFCallFrameInfo *UnwindTable::GetDebugFrameInfo() {
 187   Initialize();
 188   return m_debug_frame_up.get();
 189 }
 190
 191 CompactUnwindInfo *UnwindTable::GetCompactUnwindInfo() {
 192   Initialize();
 193   return m_compact_unwind_up.get();
 194 }
 195
 196 ArmUnwindInfo *UnwindTable::GetArmUnwindInfo() {
 197   Initialize();
 198   return m_arm_unwind_up.get();
 199 }
 200
 201 SymbolFile *UnwindTable::GetSymbolFile() { return m_module.GetSymbolFile(); }
 202
 203 ArchSpec UnwindTable::GetArchitecture() { return m_module.GetArchitecture(); }
 204
 205 bool UnwindTable::GetAllowAssemblyEmulationUnwindPlans() {
 206   if (ObjectFile *object_file = m_module.GetObjectFile())
 207     return object_file->AllowAssemblyEmulationUnwindPlans();
 208   return false;
 209 }