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/ObjectFile.h"
17 #include "lldb/Symbol/FuncUnwinders.h"
18 #include "lldb/Symbol/SymbolContext.h"
19 #include "lldb/Symbol/DWARFCallFrameInfo.h"
20 #include "lldb/Symbol/CompactUnwindInfo.h"
21 
22 // There is one UnwindTable object per ObjectFile.
23 // It contains a list of Unwind objects -- one per function, populated lazily -- for the ObjectFile.
24 // Each 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),
31     m_unwinds (),
32     m_initialized (false),
33     m_mutex (),
34     m_eh_frame (nullptr),
35     m_compact_unwind (nullptr)
36 {
37 }
38 
39 // We can't do some of this initialization when the ObjectFile is running its ctor; delay doing it
40 // until needed for something.
41 
42 void
43 UnwindTable::Initialize ()
44 {
45     if (m_initialized)
46         return;
47 
48     Mutex::Locker locker(m_mutex);
49 
50     if (m_initialized) // check again once we've acquired the lock
51         return;
52 
53     SectionList* sl = m_object_file.GetSectionList ();
54     if (sl)
55     {
56         SectionSP sect = sl->FindSectionByType (eSectionTypeEHFrame, true);
57         if (sect.get())
58         {
59             m_eh_frame = new DWARFCallFrameInfo(m_object_file, sect, eRegisterKindEHFrame, true);
60         }
61         sect = sl->FindSectionByType (eSectionTypeCompactUnwind, true);
62         if (sect.get())
63         {
64             m_compact_unwind = new CompactUnwindInfo(m_object_file, sect);
65         }
66     }
67 
68     m_initialized = true;
69 }
70 
71 UnwindTable::~UnwindTable ()
72 {
73     if (m_eh_frame)
74         delete m_eh_frame;
75 }
76 
77 FuncUnwindersSP
78 UnwindTable::GetFuncUnwindersContainingAddress (const Address& addr, SymbolContext &sc)
79 {
80     FuncUnwindersSP no_unwind_found;
81 
82     Initialize();
83 
84     Mutex::Locker locker(m_mutex);
85 
86     // There is an UnwindTable per object file, so we can safely use file handles
87     addr_t file_addr = addr.GetFileAddress();
88     iterator end = m_unwinds.end ();
89     iterator insert_pos = end;
90     if (!m_unwinds.empty())
91     {
92         insert_pos = m_unwinds.lower_bound (file_addr);
93         iterator pos = insert_pos;
94         if ((pos == m_unwinds.end ()) || (pos != m_unwinds.begin() && pos->second->GetFunctionStartAddress() != addr))
95             --pos;
96 
97         if (pos->second->ContainsAddress (addr))
98             return pos->second;
99     }
100 
101     AddressRange range;
102     if (!sc.GetAddressRange(eSymbolContextFunction | eSymbolContextSymbol, 0, false, range) || !range.GetBaseAddress().IsValid())
103     {
104         // Does the eh_frame unwind info has a function bounds for this addr?
105         if (m_eh_frame == nullptr || !m_eh_frame->GetAddressRange (addr, range))
106         {
107             return no_unwind_found;
108         }
109     }
110 
111     FuncUnwindersSP func_unwinder_sp(new FuncUnwinders(*this, range));
112     m_unwinds.insert (insert_pos, std::make_pair(range.GetBaseAddress().GetFileAddress(), func_unwinder_sp));
113 //    StreamFile s(stdout, false);
114 //    Dump (s);
115     return func_unwinder_sp;
116 }
117 
118 // Ignore any existing FuncUnwinders for this function, create a new one and don't add it to the
119 // UnwindTable.  This is intended for use by target modules show-unwind where we want to create
120 // new UnwindPlans, not re-use existing ones.
121 
122 FuncUnwindersSP
123 UnwindTable::GetUncachedFuncUnwindersContainingAddress (const Address& addr, SymbolContext &sc)
124 {
125     FuncUnwindersSP no_unwind_found;
126     Initialize();
127 
128     AddressRange range;
129     if (!sc.GetAddressRange(eSymbolContextFunction | eSymbolContextSymbol, 0, false, range) || !range.GetBaseAddress().IsValid())
130     {
131         // Does the eh_frame unwind info has a function bounds for this addr?
132         if (m_eh_frame == nullptr || !m_eh_frame->GetAddressRange (addr, range))
133         {
134             return no_unwind_found;
135         }
136     }
137 
138     FuncUnwindersSP func_unwinder_sp(new FuncUnwinders(*this, range));
139     return func_unwinder_sp;
140 }
141 
142 
143 void
144 UnwindTable::Dump (Stream &s)
145 {
146     Mutex::Locker locker(m_mutex);
147     s.Printf("UnwindTable for '%s':\n", m_object_file.GetFileSpec().GetPath().c_str());
148     const_iterator begin = m_unwinds.begin();
149     const_iterator end = m_unwinds.end();
150     for (const_iterator pos = begin; pos != end; ++pos)
151     {
152         s.Printf ("[%u] 0x%16.16" PRIx64 "\n", (unsigned)std::distance (begin, pos), pos->first);
153     }
154     s.EOL();
155 }
156 
157 DWARFCallFrameInfo *
158 UnwindTable::GetEHFrameInfo ()
159 {
160     Initialize();
161     return m_eh_frame;
162 }
163 
164 CompactUnwindInfo *
165 UnwindTable::GetCompactUnwindInfo ()
166 {
167     Initialize();
168     return m_compact_unwind;
169 }
170 
171 bool
172 UnwindTable::GetArchitecture (lldb_private::ArchSpec &arch)
173 {
174     return m_object_file.GetArchitecture (arch);
175 }
176