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