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