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 
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 = std::make_unique<DWARFCallFrameInfo>(
61         *object_file, sect, DWARFCallFrameInfo::EH);
62   }
63 
64   sect = sl->FindSectionByType(eSectionTypeDWARFDebugFrame, true);
65   if (sect) {
66     m_debug_frame_up = std::make_unique<DWARFCallFrameInfo>(
67         *object_file, sect, DWARFCallFrameInfo::DWARF);
68   }
69 
70   sect = sl->FindSectionByType(eSectionTypeCompactUnwind, true);
71   if (sect) {
72     m_compact_unwind_up =
73         std::make_unique<CompactUnwindInfo>(*object_file, sect);
74   }
75 
76   sect = sl->FindSectionByType(eSectionTypeARMexidx, true);
77   if (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 UnwindTable::~UnwindTable() = default;
87 
88 llvm::Optional<AddressRange> UnwindTable::GetAddressRange(const Address &addr,
89                                                           SymbolContext &sc) {
90   AddressRange range;
91 
92   // First check the unwind info from the object file plugin
93   if (m_object_file_unwind_up &&
94       m_object_file_unwind_up->GetAddressRange(addr, range))
95     return range;
96 
97   // Check the symbol context
98   if (sc.GetAddressRange(eSymbolContextFunction | eSymbolContextSymbol, 0,
99                          false, range) &&
100       range.GetBaseAddress().IsValid())
101     return range;
102 
103   // Does the eh_frame unwind info has a function bounds for this addr?
104   if (m_eh_frame_up && m_eh_frame_up->GetAddressRange(addr, range))
105     return range;
106 
107   // Try debug_frame as well
108   if (m_debug_frame_up && m_debug_frame_up->GetAddressRange(addr, range))
109     return range;
110 
111   return llvm::None;
112 }
113 
114 FuncUnwindersSP
115 UnwindTable::GetFuncUnwindersContainingAddress(const Address &addr,
116                                                SymbolContext &sc) {
117   Initialize();
118 
119   std::lock_guard<std::mutex> guard(m_mutex);
120 
121   // There is an UnwindTable per object file, so we can safely use file handles
122   addr_t file_addr = addr.GetFileAddress();
123   iterator end = m_unwinds.end();
124   iterator insert_pos = end;
125   if (!m_unwinds.empty()) {
126     insert_pos = m_unwinds.lower_bound(file_addr);
127     iterator pos = insert_pos;
128     if ((pos == m_unwinds.end()) ||
129         (pos != m_unwinds.begin() &&
130          pos->second->GetFunctionStartAddress() != addr))
131       --pos;
132 
133     if (pos->second->ContainsAddress(addr))
134       return pos->second;
135   }
136 
137   auto range_or = GetAddressRange(addr, sc);
138   if (!range_or)
139     return nullptr;
140 
141   FuncUnwindersSP func_unwinder_sp(new FuncUnwinders(*this, *range_or));
142   m_unwinds.insert(insert_pos,
143                    std::make_pair(range_or->GetBaseAddress().GetFileAddress(),
144                                   func_unwinder_sp));
145   return func_unwinder_sp;
146 }
147 
148 // Ignore any existing FuncUnwinders for this function, create a new one and
149 // don't add it to the UnwindTable.  This is intended for use by target modules
150 // show-unwind where we want to create new UnwindPlans, not re-use existing
151 // ones.
152 FuncUnwindersSP
153 UnwindTable::GetUncachedFuncUnwindersContainingAddress(const Address &addr,
154                                                        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 }
210