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_scanned_all_unwind_sources(false),
  34       m_mutex(), m_object_file_unwind_up(), m_eh_frame_up(),
  35       m_compact_unwind_up(), 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 void UnwindTable::Initialize() {
  40   if (m_scanned_all_unwind_sources)
  41     return;
  42
  43   std::lock_guard<std::mutex> guard(m_mutex);
  44
  45   if (m_scanned_all_unwind_sources) // check again once we've acquired the lock
  46     return;
  47
  48   ObjectFile *object_file = m_module.GetObjectFile();
  49   if (!object_file)
  50     return;
  51
  52   m_scanned_all_unwind_sources = true;
  53
  54   if (!m_object_file_unwind_up)
  55     m_object_file_unwind_up = object_file->CreateCallFrameInfo();
  56
  57   SectionList *sl = m_module.GetSectionList();
  58   if (!sl)
  59     return;
  60
  61   SectionSP sect = sl->FindSectionByType(eSectionTypeEHFrame, true);
  62   if (!m_eh_frame_up && sect)
  63     m_eh_frame_up = std::make_unique<DWARFCallFrameInfo>(
  64         *object_file, sect, DWARFCallFrameInfo::EH);
  65
  66   sect = sl->FindSectionByType(eSectionTypeDWARFDebugFrame, true);
  67   if (!m_debug_frame_up && sect)
  68     m_debug_frame_up = std::make_unique<DWARFCallFrameInfo>(
  69         *object_file, sect, DWARFCallFrameInfo::DWARF);
  70
  71   sect = sl->FindSectionByType(eSectionTypeCompactUnwind, true);
  72   if (!m_compact_unwind_up && sect)
  73     m_compact_unwind_up =
  74         std::make_unique<CompactUnwindInfo>(*object_file, sect);
  75
  76   sect = sl->FindSectionByType(eSectionTypeARMexidx, true);
  77   if (!m_arm_unwind_up && sect) {
  78     SectionSP sect_extab = sl->FindSectionByType(eSectionTypeARMextab, true);
  79     if (sect_extab.get()) {
  80       m_arm_unwind_up =
  81           std::make_unique<ArmUnwindInfo>(*object_file, sect, sect_extab);
  82     }
  83   }
  84 }
  85
  86 void UnwindTable::ModuleWasUpdated() {
  87   std::lock_guard<std::mutex> guard(m_mutex);
  88   m_scanned_all_unwind_sources = false;
  89 }
  90
  91 UnwindTable::~UnwindTable() = default;
  92
  93 std::optional<AddressRange>
  94 UnwindTable::GetAddressRange(const Address &addr, const SymbolContext &sc) {
  95   AddressRange range;
  96
  97   // First check the unwind info from the object file plugin
  98   if (m_object_file_unwind_up &&
  99       m_object_file_unwind_up->GetAddressRange(addr, range))
 100     return range;
 101
 102   // Check the symbol context
 103   if (sc.GetAddressRange(eSymbolContextFunction | eSymbolContextSymbol, 0,
 104                          false, range) &&
 105       range.GetBaseAddress().IsValid())
 106     return range;
 107
 108   // Does the eh_frame unwind info has a function bounds for this addr?
 109   if (m_eh_frame_up && m_eh_frame_up->GetAddressRange(addr, range))
 110     return range;
 111
 112   // Try debug_frame as well
 113   if (m_debug_frame_up && m_debug_frame_up->GetAddressRange(addr, range))
 114     return range;
 115
 116   return std::nullopt;
 117 }
 118
 119 FuncUnwindersSP
 120 UnwindTable::GetFuncUnwindersContainingAddress(const Address &addr,
 121                                                SymbolContext &sc) {
 122   Initialize();
 123
 124   std::lock_guard<std::mutex> guard(m_mutex);
 125
 126   // There is an UnwindTable per object file, so we can safely use file handles
 127   addr_t file_addr = addr.GetFileAddress();
 128   iterator end = m_unwinds.end();
 129   iterator insert_pos = end;
 130   if (!m_unwinds.empty()) {
 131     insert_pos = m_unwinds.lower_bound(file_addr);
 132     iterator pos = insert_pos;
 133     if ((pos == m_unwinds.end()) ||
 134         (pos != m_unwinds.begin() &&
 135          pos->second->GetFunctionStartAddress() != addr))
 136       --pos;
 137
 138     if (pos->second->ContainsAddress(addr))
 139       return pos->second;
 140   }
 141
 142   auto range_or = GetAddressRange(addr, sc);
 143   if (!range_or)
 144     return nullptr;
 145
 146   FuncUnwindersSP func_unwinder_sp(new FuncUnwinders(*this, *range_or));
 147   m_unwinds.insert(insert_pos,
 148                    std::make_pair(range_or->GetBaseAddress().GetFileAddress(),
 149                                   func_unwinder_sp));
 150   return func_unwinder_sp;
 151 }
 152
 153 // Ignore any existing FuncUnwinders for this function, create a new one and
 154 // don't add it to the UnwindTable.  This is intended for use by target modules
 155 // show-unwind where we want to create new UnwindPlans, not re-use existing
 156 // ones.
 157 FuncUnwindersSP UnwindTable::GetUncachedFuncUnwindersContainingAddress(
 158     const Address &addr, const SymbolContext &sc) {
 159   Initialize();
 160
 161   auto range_or = GetAddressRange(addr, sc);
 162   if (!range_or)
 163     return nullptr;
 164
 165   return std::make_shared<FuncUnwinders>(*this, *range_or);
 166 }
 167
 168 void UnwindTable::Dump(Stream &s) {
 169   std::lock_guard<std::mutex> guard(m_mutex);
 170   s.Format("UnwindTable for '{0}':\n", m_module.GetFileSpec());
 171   const_iterator begin = m_unwinds.begin();
 172   const_iterator end = m_unwinds.end();
 173   for (const_iterator pos = begin; pos != end; ++pos) {
 174     s.Printf("[%u] 0x%16.16" PRIx64 "\n", (unsigned)std::distance(begin, pos),
 175              pos->first);
 176   }
 177   s.EOL();
 178 }
 179
 180 lldb_private::CallFrameInfo *UnwindTable::GetObjectFileUnwindInfo() {
 181   Initialize();
 182   return m_object_file_unwind_up.get();
 183 }
 184
 185 DWARFCallFrameInfo *UnwindTable::GetEHFrameInfo() {
 186   Initialize();
 187   return m_eh_frame_up.get();
 188 }
 189
 190 DWARFCallFrameInfo *UnwindTable::GetDebugFrameInfo() {
 191   Initialize();
 192   return m_debug_frame_up.get();
 193 }
 194
 195 CompactUnwindInfo *UnwindTable::GetCompactUnwindInfo() {
 196   Initialize();
 197   return m_compact_unwind_up.get();
 198 }
 199
 200 ArmUnwindInfo *UnwindTable::GetArmUnwindInfo() {
 201   Initialize();
 202   return m_arm_unwind_up.get();
 203 }
 204
 205 SymbolFile *UnwindTable::GetSymbolFile() { return m_module.GetSymbolFile(); }
 206
 207 ArchSpec UnwindTable::GetArchitecture() { return m_module.GetArchitecture(); }
 208
 209 bool UnwindTable::GetAllowAssemblyEmulationUnwindPlans() {
 210   if (ObjectFile *object_file = m_module.GetObjectFile())
 211     return object_file->AllowAssemblyEmulationUnwindPlans();
 212   return false;
 213 }