1//===-- UnwindTable.cpp ---------------------------------------------------===//
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 <cstdio>
12#include <optional>
13
14#include "lldb/Core/Module.h"
15#include "lldb/Core/Section.h"
16#include "lldb/Symbol/ArmUnwindInfo.h"
17#include "lldb/Symbol/CallFrameInfo.h"
18#include "lldb/Symbol/CompactUnwindInfo.h"
19#include "lldb/Symbol/DWARFCallFrameInfo.h"
20#include "lldb/Symbol/FuncUnwinders.h"
21#include "lldb/Symbol/ObjectFile.h"
22#include "lldb/Symbol/SymbolContext.h"
23#include "lldb/Symbol/SymbolVendor.h"
24
25// There is one UnwindTable object per ObjectFile. It contains a list of Unwind
26// objects -- one per function, populated lazily -- for the ObjectFile. Each
27// Unwind object has multiple UnwindPlans for different scenarios.
28
29using namespace lldb;
30using namespace lldb_private;
31
32UnwindTable::UnwindTable(Module &module)
33 : m_module(module), m_unwinds(), m_scanned_all_unwind_sources(false),
34 m_mutex(), m_object_file_unwind_up(), m_eh_frame_up(),
35 m_compact_unwind_up(), m_arm_unwind_up() {}
36
37// We can't do some of this initialization when the ObjectFile is running its
38// ctor; delay doing it until needed for something.
39void UnwindTable::Initialize() {
40 if (m_scanned_all_unwind_sources)
41 return;
42
43 std::lock_guard<std::mutex> guard(m_mutex);
44
45 if (m_scanned_all_unwind_sources) // check again once we've acquired the lock
46 return;
47
48 ObjectFile *object_file = m_module.GetObjectFile();
49 if (!object_file)
50 return;
51
52 m_scanned_all_unwind_sources = true;
53
54 if (!m_object_file_unwind_up)
55 m_object_file_unwind_up = object_file->CreateCallFrameInfo();
56
57 SectionList *sl = m_module.GetSectionList();
58 if (!sl)
59 return;
60
61 SectionSP sect = sl->FindSectionByType(sect_type: eSectionTypeEHFrame, check_children: true);
62 if (!m_eh_frame_up && sect)
63 m_eh_frame_up = std::make_unique<DWARFCallFrameInfo>(
64 args&: *object_file, args&: sect, args: DWARFCallFrameInfo::EH);
65
66 sect = sl->FindSectionByType(sect_type: eSectionTypeDWARFDebugFrame, check_children: true);
67 if (!m_debug_frame_up && sect)
68 m_debug_frame_up = std::make_unique<DWARFCallFrameInfo>(
69 args&: *object_file, args&: sect, args: DWARFCallFrameInfo::DWARF);
70
71 sect = sl->FindSectionByType(sect_type: eSectionTypeCompactUnwind, check_children: true);
72 if (!m_compact_unwind_up && sect)
73 m_compact_unwind_up =
74 std::make_unique<CompactUnwindInfo>(args&: *object_file, args&: sect);
75
76 sect = sl->FindSectionByType(sect_type: eSectionTypeARMexidx, check_children: true);
77 if (!m_arm_unwind_up && sect) {
78 SectionSP sect_extab = sl->FindSectionByType(sect_type: eSectionTypeARMextab, check_children: true);
79 if (sect_extab.get()) {
80 m_arm_unwind_up =
81 std::make_unique<ArmUnwindInfo>(args&: *object_file, args&: sect, args&: sect_extab);
82 }
83 }
84}
85
86void UnwindTable::ModuleWasUpdated() {
87 std::lock_guard<std::mutex> guard(m_mutex);
88 m_scanned_all_unwind_sources = false;
89 m_unwinds.clear();
90}
91
92UnwindTable::~UnwindTable() = default;
93
94AddressRanges UnwindTable::GetAddressRanges(const Address &addr,
95 const SymbolContext &sc) {
96 AddressRange range;
97
98 // First check the unwind info from the object file plugin
99 if (m_object_file_unwind_up &&
100 m_object_file_unwind_up->GetAddressRange(addr, range))
101 return {range};
102
103 // Check the symbol context
104 AddressRanges result;
105 for (size_t idx = 0;
106 sc.GetAddressRange(scope: eSymbolContextFunction | eSymbolContextSymbol, range_idx: idx,
107 use_inline_block_range: false, range) &&
108 range.GetBaseAddress().IsValid();
109 ++idx)
110 result.push_back(x: range);
111 if (!result.empty())
112 return result;
113
114 // Does the eh_frame unwind info has a function bounds for this addr?
115 if (m_eh_frame_up && m_eh_frame_up->GetAddressRange(addr, range))
116 return {range};
117
118 // Try debug_frame as well
119 if (m_debug_frame_up && m_debug_frame_up->GetAddressRange(addr, range))
120 return {range};
121
122 return {};
123}
124
125static Address GetFunctionOrSymbolAddress(const Address &addr,
126 const SymbolContext &sc) {
127 if (Address result = sc.GetFunctionOrSymbolAddress(); result.IsValid())
128 return result;
129 return addr;
130}
131
132FuncUnwindersSP
133UnwindTable::GetFuncUnwindersContainingAddress(const Address &addr,
134 const SymbolContext &sc) {
135 Initialize();
136
137 std::lock_guard<std::mutex> guard(m_mutex);
138
139 // There is an UnwindTable per object file, so we can safely use file handles
140 addr_t file_addr = addr.GetFileAddress();
141 iterator insert_pos = m_unwinds.upper_bound(x: file_addr);
142 if (insert_pos != m_unwinds.begin()) {
143 auto pos = std::prev(x: insert_pos);
144 if (pos->second->ContainsAddress(addr))
145 return pos->second;
146 }
147
148 Address start_addr = GetFunctionOrSymbolAddress(addr, sc);
149 AddressRanges ranges = GetAddressRanges(addr, sc);
150 if (ranges.empty())
151 return nullptr;
152
153 auto func_unwinder_sp =
154 std::make_shared<FuncUnwinders>(args&: *this, args&: start_addr, args&: ranges);
155 for (const AddressRange &range : ranges)
156 m_unwinds.emplace_hint(pos: insert_pos, args: range.GetBaseAddress().GetFileAddress(),
157 args&: func_unwinder_sp);
158 return func_unwinder_sp;
159}
160
161// Ignore any existing FuncUnwinders for this function, create a new one and
162// don't add it to the UnwindTable. This is intended for use by target modules
163// show-unwind where we want to create new UnwindPlans, not re-use existing
164// ones.
165FuncUnwindersSP UnwindTable::GetUncachedFuncUnwindersContainingAddress(
166 const Address &addr, const SymbolContext &sc) {
167 Initialize();
168
169 Address start_addr = GetFunctionOrSymbolAddress(addr, sc);
170 AddressRanges ranges = GetAddressRanges(addr, sc);
171 if (ranges.empty())
172 return nullptr;
173
174 return std::make_shared<FuncUnwinders>(args&: *this, args&: start_addr, args: std::move(ranges));
175}
176
177void UnwindTable::Dump(Stream &s) {
178 std::lock_guard<std::mutex> guard(m_mutex);
179 s.Format(format: "UnwindTable for '{0}':\n", args: m_module.GetFileSpec());
180 const_iterator begin = m_unwinds.begin();
181 const_iterator end = m_unwinds.end();
182 for (const_iterator pos = begin; pos != end; ++pos) {
183 s.Printf(format: "[%u] 0x%16.16" PRIx64 "\n", (unsigned)std::distance(first: begin, last: pos),
184 pos->first);
185 }
186 s.EOL();
187}
188
189lldb_private::CallFrameInfo *UnwindTable::GetObjectFileUnwindInfo() {
190 Initialize();
191 return m_object_file_unwind_up.get();
192}
193
194DWARFCallFrameInfo *UnwindTable::GetEHFrameInfo() {
195 Initialize();
196 return m_eh_frame_up.get();
197}
198
199DWARFCallFrameInfo *UnwindTable::GetDebugFrameInfo() {
200 Initialize();
201 return m_debug_frame_up.get();
202}
203
204CompactUnwindInfo *UnwindTable::GetCompactUnwindInfo() {
205 Initialize();
206 return m_compact_unwind_up.get();
207}
208
209ArmUnwindInfo *UnwindTable::GetArmUnwindInfo() {
210 Initialize();
211 return m_arm_unwind_up.get();
212}
213
214SymbolFile *UnwindTable::GetSymbolFile() { return m_module.GetSymbolFile(); }
215
216ArchSpec UnwindTable::GetArchitecture() { return m_module.GetArchitecture(); }
217
218bool UnwindTable::GetAllowAssemblyEmulationUnwindPlans() {
219 if (ObjectFile *object_file = m_module.GetObjectFile())
220 return object_file->AllowAssemblyEmulationUnwindPlans();
221 return false;
222}
223

source code of lldb/source/Symbol/UnwindTable.cpp