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 
48   SectionList *sl = m_object_file.GetSectionList();
49   if (sl) {
50     SectionSP sect = sl->FindSectionByType(eSectionTypeEHFrame, true);
51     if (sect.get()) {
52       m_eh_frame_up.reset(new DWARFCallFrameInfo(m_object_file, sect,
53                                                  eRegisterKindEHFrame, true));
54     }
55     sect = sl->FindSectionByType(eSectionTypeCompactUnwind, true);
56     if (sect.get()) {
57       m_compact_unwind_up.reset(new CompactUnwindInfo(m_object_file, sect));
58     }
59     sect = sl->FindSectionByType(eSectionTypeARMexidx, true);
60     if (sect.get()) {
61       SectionSP sect_extab = sl->FindSectionByType(eSectionTypeARMextab, true);
62       if (sect_extab.get()) {
63         m_arm_unwind_up.reset(
64             new ArmUnwindInfo(m_object_file, sect, sect_extab));
65       }
66     }
67   }
68 
69   m_initialized = true;
70 }
71 
72 UnwindTable::~UnwindTable() {}
73 
74 FuncUnwindersSP
75 UnwindTable::GetFuncUnwindersContainingAddress(const Address &addr,
76                                                SymbolContext &sc) {
77   FuncUnwindersSP no_unwind_found;
78 
79   Initialize();
80 
81   std::lock_guard<std::mutex> guard(m_mutex);
82 
83   // There is an UnwindTable per object file, so we can safely use file handles
84   addr_t file_addr = addr.GetFileAddress();
85   iterator end = m_unwinds.end();
86   iterator insert_pos = end;
87   if (!m_unwinds.empty()) {
88     insert_pos = m_unwinds.lower_bound(file_addr);
89     iterator pos = insert_pos;
90     if ((pos == m_unwinds.end()) ||
91         (pos != m_unwinds.begin() &&
92          pos->second->GetFunctionStartAddress() != addr))
93       --pos;
94 
95     if (pos->second->ContainsAddress(addr))
96       return pos->second;
97   }
98 
99   AddressRange range;
100   if (!sc.GetAddressRange(eSymbolContextFunction | eSymbolContextSymbol, 0,
101                           false, range) ||
102       !range.GetBaseAddress().IsValid()) {
103     // Does the eh_frame unwind info has a function bounds for this addr?
104     if (m_eh_frame_up == nullptr ||
105         !m_eh_frame_up->GetAddressRange(addr, range)) {
106       return no_unwind_found;
107     }
108   }
109 
110   FuncUnwindersSP func_unwinder_sp(new FuncUnwinders(*this, range));
111   m_unwinds.insert(insert_pos,
112                    std::make_pair(range.GetBaseAddress().GetFileAddress(),
113                                   func_unwinder_sp));
114   //    StreamFile s(stdout, false);
115   //    Dump (s);
116   return func_unwinder_sp;
117 }
118 
119 // Ignore any existing FuncUnwinders for this function, create a new one and
120 // don't add it to the
121 // UnwindTable.  This is intended for use by target modules show-unwind where we
122 // want to create
123 // new UnwindPlans, not re-use existing ones.
124 
125 FuncUnwindersSP
126 UnwindTable::GetUncachedFuncUnwindersContainingAddress(const Address &addr,
127                                                        SymbolContext &sc) {
128   FuncUnwindersSP no_unwind_found;
129   Initialize();
130 
131   AddressRange range;
132   if (!sc.GetAddressRange(eSymbolContextFunction | eSymbolContextSymbol, 0,
133                           false, range) ||
134       !range.GetBaseAddress().IsValid()) {
135     // Does the eh_frame unwind info has a function bounds for this addr?
136     if (m_eh_frame_up == nullptr ||
137         !m_eh_frame_up->GetAddressRange(addr, range)) {
138       return no_unwind_found;
139     }
140   }
141 
142   FuncUnwindersSP func_unwinder_sp(new FuncUnwinders(*this, range));
143   return func_unwinder_sp;
144 }
145 
146 void UnwindTable::Dump(Stream &s) {
147   std::lock_guard<std::mutex> guard(m_mutex);
148   s.Printf("UnwindTable for '%s':\n",
149            m_object_file.GetFileSpec().GetPath().c_str());
150   const_iterator begin = m_unwinds.begin();
151   const_iterator end = m_unwinds.end();
152   for (const_iterator pos = begin; pos != end; ++pos) {
153     s.Printf("[%u] 0x%16.16" PRIx64 "\n", (unsigned)std::distance(begin, pos),
154              pos->first);
155   }
156   s.EOL();
157 }
158 
159 DWARFCallFrameInfo *UnwindTable::GetEHFrameInfo() {
160   Initialize();
161   return m_eh_frame_up.get();
162 }
163 
164 CompactUnwindInfo *UnwindTable::GetCompactUnwindInfo() {
165   Initialize();
166   return m_compact_unwind_up.get();
167 }
168 
169 ArmUnwindInfo *UnwindTable::GetArmUnwindInfo() {
170   Initialize();
171   return m_arm_unwind_up.get();
172 }
173 
174 bool UnwindTable::GetArchitecture(lldb_private::ArchSpec &arch) {
175   return m_object_file.GetArchitecture(arch);
176 }
177 
178 bool UnwindTable::GetAllowAssemblyEmulationUnwindPlans() {
179   return m_object_file.AllowAssemblyEmulationUnwindPlans();
180 }
181