1 //===-- UnwindTable.cpp -----------------------------------------*- C++ -*-===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 
10 #include "lldb/Symbol/UnwindTable.h"
11 
12 #include <stdio.h>
13 
14 #include "lldb/Core/Module.h"
15 #include "lldb/Core/Section.h"
16 #include "lldb/Symbol/ArmUnwindInfo.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 
23 // There is one UnwindTable object per ObjectFile.
24 // It contains a list of Unwind objects -- one per function, populated lazily --
25 // for the ObjectFile.
26 // Each Unwind object has multiple UnwindPlans for different scenarios.
27 
28 using namespace lldb;
29 using namespace lldb_private;
30 
31 UnwindTable::UnwindTable(ObjectFile &objfile)
32     : m_object_file(objfile), m_unwinds(), m_initialized(false), m_mutex(),
33       m_eh_frame_up(), m_compact_unwind_up(), m_arm_unwind_up() {}
34 
35 // We can't do some of this initialization when the ObjectFile is running its
36 // ctor; delay doing it
37 // 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 
49   SectionList *sl = m_object_file.GetSectionList();
50   if (!sl)
51     return;
52 
53   SectionSP sect = sl->FindSectionByType(eSectionTypeEHFrame, true);
54   if (sect.get()) {
55     m_eh_frame_up.reset(
56         new DWARFCallFrameInfo(m_object_file, sect, DWARFCallFrameInfo::EH));
57   }
58 
59   sect = sl->FindSectionByType(eSectionTypeDWARFDebugFrame, true);
60   if (sect) {
61     m_debug_frame_up.reset(
62         new DWARFCallFrameInfo(m_object_file, sect, DWARFCallFrameInfo::DWARF));
63   }
64 
65   sect = sl->FindSectionByType(eSectionTypeCompactUnwind, true);
66   if (sect) {
67     m_compact_unwind_up.reset(new CompactUnwindInfo(m_object_file, sect));
68   }
69 
70   sect = sl->FindSectionByType(eSectionTypeARMexidx, true);
71   if (sect) {
72     SectionSP sect_extab = sl->FindSectionByType(eSectionTypeARMextab, true);
73     if (sect_extab.get()) {
74       m_arm_unwind_up.reset(new ArmUnwindInfo(m_object_file, sect, sect_extab));
75     }
76   }
77 }
78 
79 UnwindTable::~UnwindTable() {}
80 
81 llvm::Optional<AddressRange> UnwindTable::GetAddressRange(const Address &addr,
82                                                           SymbolContext &sc) {
83   AddressRange range;
84 
85   // First check the symbol context
86   if (sc.GetAddressRange(eSymbolContextFunction | eSymbolContextSymbol, 0,
87                          false, range) &&
88       range.GetBaseAddress().IsValid())
89     return range;
90 
91   // Does the eh_frame unwind info has a function bounds for this addr?
92   if (m_eh_frame_up && m_eh_frame_up->GetAddressRange(addr, range))
93     return range;
94 
95   // Try debug_frame as well
96   if (m_debug_frame_up && m_debug_frame_up->GetAddressRange(addr, range))
97     return range;
98 
99   return llvm::None;
100 }
101 
102 FuncUnwindersSP
103 UnwindTable::GetFuncUnwindersContainingAddress(const Address &addr,
104                                                SymbolContext &sc) {
105   Initialize();
106 
107   std::lock_guard<std::mutex> guard(m_mutex);
108 
109   // There is an UnwindTable per object file, so we can safely use file handles
110   addr_t file_addr = addr.GetFileAddress();
111   iterator end = m_unwinds.end();
112   iterator insert_pos = end;
113   if (!m_unwinds.empty()) {
114     insert_pos = m_unwinds.lower_bound(file_addr);
115     iterator pos = insert_pos;
116     if ((pos == m_unwinds.end()) ||
117         (pos != m_unwinds.begin() &&
118          pos->second->GetFunctionStartAddress() != addr))
119       --pos;
120 
121     if (pos->second->ContainsAddress(addr))
122       return pos->second;
123   }
124 
125   auto range_or = GetAddressRange(addr, sc);
126   if (!range_or)
127     return nullptr;
128 
129   FuncUnwindersSP func_unwinder_sp(new FuncUnwinders(*this, *range_or));
130   m_unwinds.insert(insert_pos,
131                    std::make_pair(range_or->GetBaseAddress().GetFileAddress(),
132                                   func_unwinder_sp));
133   return func_unwinder_sp;
134 }
135 
136 // Ignore any existing FuncUnwinders for this function, create a new one and
137 // don't add it to the
138 // UnwindTable.  This is intended for use by target modules show-unwind where we
139 // want to create
140 // new UnwindPlans, not re-use existing ones.
141 FuncUnwindersSP
142 UnwindTable::GetUncachedFuncUnwindersContainingAddress(const Address &addr,
143                                                        SymbolContext &sc) {
144   Initialize();
145 
146   auto range_or = GetAddressRange(addr, sc);
147   if (!range_or)
148     return nullptr;
149 
150   return std::make_shared<FuncUnwinders>(*this, *range_or);
151 }
152 
153 void UnwindTable::Dump(Stream &s) {
154   std::lock_guard<std::mutex> guard(m_mutex);
155   s.Printf("UnwindTable for '%s':\n",
156            m_object_file.GetFileSpec().GetPath().c_str());
157   const_iterator begin = m_unwinds.begin();
158   const_iterator end = m_unwinds.end();
159   for (const_iterator pos = begin; pos != end; ++pos) {
160     s.Printf("[%u] 0x%16.16" PRIx64 "\n", (unsigned)std::distance(begin, pos),
161              pos->first);
162   }
163   s.EOL();
164 }
165 
166 DWARFCallFrameInfo *UnwindTable::GetEHFrameInfo() {
167   Initialize();
168   return m_eh_frame_up.get();
169 }
170 
171 DWARFCallFrameInfo *UnwindTable::GetDebugFrameInfo() {
172   Initialize();
173   return m_debug_frame_up.get();
174 }
175 
176 CompactUnwindInfo *UnwindTable::GetCompactUnwindInfo() {
177   Initialize();
178   return m_compact_unwind_up.get();
179 }
180 
181 ArmUnwindInfo *UnwindTable::GetArmUnwindInfo() {
182   Initialize();
183   return m_arm_unwind_up.get();
184 }
185 
186 bool UnwindTable::GetArchitecture(lldb_private::ArchSpec &arch) {
187   return m_object_file.GetArchitecture(arch);
188 }
189 
190 bool UnwindTable::GetAllowAssemblyEmulationUnwindPlans() {
191   return m_object_file.AllowAssemblyEmulationUnwindPlans();
192 }
193