1 //===-- UnwindTable.cpp -----------------------------------------*- C++ -*-===//
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 <stdio.h>
12 
13 #include "lldb/Core/Module.h"
14 #include "lldb/Core/Section.h"
15 #include "lldb/Symbol/ArmUnwindInfo.h"
16 #include "lldb/Symbol/CallFrameInfo.h"
17 #include "lldb/Symbol/CompactUnwindInfo.h"
18 #include "lldb/Symbol/DWARFCallFrameInfo.h"
19 #include "lldb/Symbol/FuncUnwinders.h"
20 #include "lldb/Symbol/ObjectFile.h"
21 #include "lldb/Symbol/SymbolContext.h"
22 #include "lldb/Symbol/SymbolVendor.h"
23 
24 // There is one UnwindTable object per ObjectFile. It contains a list of Unwind
25 // objects -- one per function, populated lazily -- for the ObjectFile. Each
26 // Unwind object has multiple UnwindPlans for different scenarios.
27 
28 using namespace lldb;
29 using namespace lldb_private;
30 
31 UnwindTable::UnwindTable(Module &module)
32     : m_module(module), m_unwinds(), m_initialized(false), m_mutex(),
33       m_object_file_unwind_up(), m_eh_frame_up(), m_compact_unwind_up(),
34       m_arm_unwind_up() {}
35 
36 // We can't do some of this initialization when the ObjectFile is running its
37 // ctor; delay doing it until needed for something.
38 
39 void UnwindTable::Initialize() {
40   if (m_initialized)
41     return;
42 
43   std::lock_guard<std::mutex> guard(m_mutex);
44 
45   if (m_initialized) // check again once we've acquired the lock
46     return;
47   m_initialized = true;
48   ObjectFile *object_file = m_module.GetObjectFile();
49   if (!object_file)
50     return;
51 
52   m_object_file_unwind_up = object_file->CreateCallFrameInfo();
53 
54   SectionList *sl = m_module.GetSectionList();
55   if (!sl)
56     return;
57 
58   SectionSP sect = sl->FindSectionByType(eSectionTypeEHFrame, true);
59   if (sect.get()) {
60     m_eh_frame_up.reset(
61         new DWARFCallFrameInfo(*object_file, sect, DWARFCallFrameInfo::EH));
62   }
63 
64   sect = sl->FindSectionByType(eSectionTypeDWARFDebugFrame, true);
65   if (sect) {
66     m_debug_frame_up.reset(
67         new DWARFCallFrameInfo(*object_file, sect, DWARFCallFrameInfo::DWARF));
68   }
69 
70   sect = sl->FindSectionByType(eSectionTypeCompactUnwind, true);
71   if (sect) {
72     m_compact_unwind_up.reset(new CompactUnwindInfo(*object_file, sect));
73   }
74 
75   sect = sl->FindSectionByType(eSectionTypeARMexidx, true);
76   if (sect) {
77     SectionSP sect_extab = sl->FindSectionByType(eSectionTypeARMextab, true);
78     if (sect_extab.get()) {
79       m_arm_unwind_up.reset(new ArmUnwindInfo(*object_file, sect, sect_extab));
80     }
81   }
82 }
83 
84 UnwindTable::~UnwindTable() {}
85 
86 llvm::Optional<AddressRange> UnwindTable::GetAddressRange(const Address &addr,
87                                                           SymbolContext &sc) {
88   AddressRange range;
89 
90   // First check the unwind info from the object file plugin
91   if (m_object_file_unwind_up &&
92       m_object_file_unwind_up->GetAddressRange(addr, range))
93     return range;
94 
95   // Check the symbol context
96   if (sc.GetAddressRange(eSymbolContextFunction | eSymbolContextSymbol, 0,
97                          false, range) &&
98       range.GetBaseAddress().IsValid())
99     return range;
100 
101   // Does the eh_frame unwind info has a function bounds for this addr?
102   if (m_eh_frame_up && m_eh_frame_up->GetAddressRange(addr, range))
103     return range;
104 
105   // Try debug_frame as well
106   if (m_debug_frame_up && m_debug_frame_up->GetAddressRange(addr, range))
107     return range;
108 
109   return llvm::None;
110 }
111 
112 FuncUnwindersSP
113 UnwindTable::GetFuncUnwindersContainingAddress(const Address &addr,
114                                                SymbolContext &sc) {
115   Initialize();
116 
117   std::lock_guard<std::mutex> guard(m_mutex);
118 
119   // There is an UnwindTable per object file, so we can safely use file handles
120   addr_t file_addr = addr.GetFileAddress();
121   iterator end = m_unwinds.end();
122   iterator insert_pos = end;
123   if (!m_unwinds.empty()) {
124     insert_pos = m_unwinds.lower_bound(file_addr);
125     iterator pos = insert_pos;
126     if ((pos == m_unwinds.end()) ||
127         (pos != m_unwinds.begin() &&
128          pos->second->GetFunctionStartAddress() != addr))
129       --pos;
130 
131     if (pos->second->ContainsAddress(addr))
132       return pos->second;
133   }
134 
135   auto range_or = GetAddressRange(addr, sc);
136   if (!range_or)
137     return nullptr;
138 
139   FuncUnwindersSP func_unwinder_sp(new FuncUnwinders(*this, *range_or));
140   m_unwinds.insert(insert_pos,
141                    std::make_pair(range_or->GetBaseAddress().GetFileAddress(),
142                                   func_unwinder_sp));
143   return func_unwinder_sp;
144 }
145 
146 // Ignore any existing FuncUnwinders for this function, create a new one and
147 // don't add it to the UnwindTable.  This is intended for use by target modules
148 // show-unwind where we want to create new UnwindPlans, not re-use existing
149 // ones.
150 FuncUnwindersSP
151 UnwindTable::GetUncachedFuncUnwindersContainingAddress(const Address &addr,
152                                                        SymbolContext &sc) {
153   Initialize();
154 
155   auto range_or = GetAddressRange(addr, sc);
156   if (!range_or)
157     return nullptr;
158 
159   return std::make_shared<FuncUnwinders>(*this, *range_or);
160 }
161 
162 void UnwindTable::Dump(Stream &s) {
163   std::lock_guard<std::mutex> guard(m_mutex);
164   s.Format("UnwindTable for '{0}':\n", m_module.GetFileSpec());
165   const_iterator begin = m_unwinds.begin();
166   const_iterator end = m_unwinds.end();
167   for (const_iterator pos = begin; pos != end; ++pos) {
168     s.Printf("[%u] 0x%16.16" PRIx64 "\n", (unsigned)std::distance(begin, pos),
169              pos->first);
170   }
171   s.EOL();
172 }
173 
174 lldb_private::CallFrameInfo *UnwindTable::GetObjectFileUnwindInfo() {
175   Initialize();
176   return m_object_file_unwind_up.get();
177 }
178 
179 DWARFCallFrameInfo *UnwindTable::GetEHFrameInfo() {
180   Initialize();
181   return m_eh_frame_up.get();
182 }
183 
184 DWARFCallFrameInfo *UnwindTable::GetDebugFrameInfo() {
185   Initialize();
186   return m_debug_frame_up.get();
187 }
188 
189 CompactUnwindInfo *UnwindTable::GetCompactUnwindInfo() {
190   Initialize();
191   return m_compact_unwind_up.get();
192 }
193 
194 ArmUnwindInfo *UnwindTable::GetArmUnwindInfo() {
195   Initialize();
196   return m_arm_unwind_up.get();
197 }
198 
199 SymbolFile *UnwindTable::GetSymbolFile() { return m_module.GetSymbolFile(); }
200 
201 ArchSpec UnwindTable::GetArchitecture() { return m_module.GetArchitecture(); }
202 
203 bool UnwindTable::GetAllowAssemblyEmulationUnwindPlans() {
204   if (ObjectFile *object_file = m_module.GetObjectFile())
205     return object_file->AllowAssemblyEmulationUnwindPlans();
206   return false;
207 }
208