1 //===-- DynamicLoaderWindowsDYLD.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 "DynamicLoaderWindowsDYLD.h"
10 
11 #include "lldb/Core/Module.h"
12 #include "lldb/Core/PluginManager.h"
13 #include "lldb/Target/ExecutionContext.h"
14 #include "lldb/Target/Platform.h"
15 #include "lldb/Target/Process.h"
16 #include "lldb/Target/RegisterContext.h"
17 #include "lldb/Target/Target.h"
18 #include "lldb/Target/ThreadPlanStepInstruction.h"
19 #include "lldb/Utility/Log.h"
20 
21 #include "llvm/ADT/Triple.h"
22 
23 using namespace lldb;
24 using namespace lldb_private;
25 
26 LLDB_PLUGIN_DEFINE(DynamicLoaderWindowsDYLD)
27 
28 DynamicLoaderWindowsDYLD::DynamicLoaderWindowsDYLD(Process *process)
29     : DynamicLoader(process) {}
30 
31 DynamicLoaderWindowsDYLD::~DynamicLoaderWindowsDYLD() = default;
32 
33 void DynamicLoaderWindowsDYLD::Initialize() {
34   PluginManager::RegisterPlugin(GetPluginNameStatic(),
35                                 GetPluginDescriptionStatic(), CreateInstance);
36 }
37 
38 void DynamicLoaderWindowsDYLD::Terminate() {}
39 
40 ConstString DynamicLoaderWindowsDYLD::GetPluginNameStatic() {
41   static ConstString g_plugin_name("windows-dyld");
42   return g_plugin_name;
43 }
44 
45 const char *DynamicLoaderWindowsDYLD::GetPluginDescriptionStatic() {
46   return "Dynamic loader plug-in that watches for shared library "
47          "loads/unloads in Windows processes.";
48 }
49 
50 DynamicLoader *DynamicLoaderWindowsDYLD::CreateInstance(Process *process,
51                                                         bool force) {
52   bool should_create = force;
53   if (!should_create) {
54     const llvm::Triple &triple_ref =
55         process->GetTarget().GetArchitecture().GetTriple();
56     if (triple_ref.getOS() == llvm::Triple::Win32)
57       should_create = true;
58   }
59 
60   if (should_create)
61     return new DynamicLoaderWindowsDYLD(process);
62 
63   return nullptr;
64 }
65 
66 void DynamicLoaderWindowsDYLD::OnLoadModule(lldb::ModuleSP module_sp,
67                                             const ModuleSpec module_spec,
68                                             lldb::addr_t module_addr) {
69 
70   // Resolve the module unless we already have one.
71   if (!module_sp) {
72     Status error;
73     module_sp = m_process->GetTarget().GetOrCreateModule(module_spec,
74                                              true /* notify */, &error);
75     if (error.Fail())
76       return;
77   }
78 
79   m_loaded_modules[module_sp] = module_addr;
80   UpdateLoadedSectionsCommon(module_sp, module_addr, false);
81   ModuleList module_list;
82   module_list.Append(module_sp);
83   m_process->GetTarget().ModulesDidLoad(module_list);
84 }
85 
86 void DynamicLoaderWindowsDYLD::OnUnloadModule(lldb::addr_t module_addr) {
87   Address resolved_addr;
88   if (!m_process->GetTarget().ResolveLoadAddress(module_addr, resolved_addr))
89     return;
90 
91   ModuleSP module_sp = resolved_addr.GetModule();
92   if (module_sp) {
93     m_loaded_modules.erase(module_sp);
94     UnloadSectionsCommon(module_sp);
95     ModuleList module_list;
96     module_list.Append(module_sp);
97     m_process->GetTarget().ModulesDidUnload(module_list, false);
98   }
99 }
100 
101 lldb::addr_t DynamicLoaderWindowsDYLD::GetLoadAddress(ModuleSP executable) {
102   // First, see if the load address is already cached.
103   auto it = m_loaded_modules.find(executable);
104   if (it != m_loaded_modules.end() && it->second != LLDB_INVALID_ADDRESS)
105     return it->second;
106 
107   lldb::addr_t load_addr = LLDB_INVALID_ADDRESS;
108 
109   // Second, try to get it through the process plugins.  For a remote process,
110   // the remote platform will be responsible for providing it.
111   FileSpec file_spec(executable->GetPlatformFileSpec());
112   bool is_loaded = false;
113   Status status =
114       m_process->GetFileLoadAddress(file_spec, is_loaded, load_addr);
115   // Servers other than lldb server could respond with a bogus address.
116   if (status.Success() && is_loaded && load_addr != LLDB_INVALID_ADDRESS) {
117     m_loaded_modules[executable] = load_addr;
118     return load_addr;
119   }
120 
121   return LLDB_INVALID_ADDRESS;
122 }
123 
124 void DynamicLoaderWindowsDYLD::DidAttach() {
125     Log *log(GetLogIfAnyCategoriesSet(LIBLLDB_LOG_DYNAMIC_LOADER));
126     LLDB_LOGF(log, "DynamicLoaderWindowsDYLD::%s()", __FUNCTION__);
127 
128     ModuleSP executable = GetTargetExecutable();
129 
130     if (!executable.get())
131       return;
132 
133     // Try to fetch the load address of the file from the process, since there
134     // could be randomization of the load address.
135     lldb::addr_t load_addr = GetLoadAddress(executable);
136     if (load_addr == LLDB_INVALID_ADDRESS)
137       return;
138 
139     // Request the process base address.
140     lldb::addr_t image_base = m_process->GetImageInfoAddress();
141     if (image_base == load_addr)
142       return;
143 
144     // Rebase the process's modules if there is a mismatch.
145     UpdateLoadedSections(executable, LLDB_INVALID_ADDRESS, load_addr, false);
146 
147     ModuleList module_list;
148     module_list.Append(executable);
149     m_process->GetTarget().ModulesDidLoad(module_list);
150     auto error = m_process->LoadModules();
151     LLDB_LOG_ERROR(log, std::move(error), "failed to load modules: {0}");
152 }
153 
154 void DynamicLoaderWindowsDYLD::DidLaunch() {
155   Log *log(GetLogIfAnyCategoriesSet(LIBLLDB_LOG_DYNAMIC_LOADER));
156   LLDB_LOGF(log, "DynamicLoaderWindowsDYLD::%s()", __FUNCTION__);
157 
158   ModuleSP executable = GetTargetExecutable();
159   if (!executable.get())
160     return;
161 
162   lldb::addr_t load_addr = GetLoadAddress(executable);
163   if (load_addr != LLDB_INVALID_ADDRESS) {
164     // Update the loaded sections so that the breakpoints can be resolved.
165     UpdateLoadedSections(executable, LLDB_INVALID_ADDRESS, load_addr, false);
166 
167     ModuleList module_list;
168     module_list.Append(executable);
169     m_process->GetTarget().ModulesDidLoad(module_list);
170     auto error = m_process->LoadModules();
171     LLDB_LOG_ERROR(log, std::move(error), "failed to load modules: {0}");
172   }
173 }
174 
175 Status DynamicLoaderWindowsDYLD::CanLoadImage() { return Status(); }
176 
177 ConstString DynamicLoaderWindowsDYLD::GetPluginName() {
178   return GetPluginNameStatic();
179 }
180 
181 uint32_t DynamicLoaderWindowsDYLD::GetPluginVersion() { return 1; }
182 
183 ThreadPlanSP
184 DynamicLoaderWindowsDYLD::GetStepThroughTrampolinePlan(Thread &thread,
185                                                        bool stop) {
186   auto arch = m_process->GetTarget().GetArchitecture();
187   if (arch.GetMachine() != llvm::Triple::x86) {
188     return ThreadPlanSP();
189   }
190 
191   uint64_t pc = thread.GetRegisterContext()->GetPC();
192   // Max size of an instruction in x86 is 15 bytes.
193   AddressRange range(pc, 2 * 15);
194 
195   DisassemblerSP disassembler_sp = Disassembler::DisassembleRange(
196       arch, nullptr, nullptr, m_process->GetTarget(), range);
197   if (!disassembler_sp) {
198     return ThreadPlanSP();
199   }
200 
201   InstructionList *insn_list = &disassembler_sp->GetInstructionList();
202   if (insn_list == nullptr) {
203     return ThreadPlanSP();
204   }
205 
206   // First instruction in a x86 Windows trampoline is going to be an indirect
207   // jump through the IAT and the next one will be a nop (usually there for
208   // alignment purposes). e.g.:
209   //     0x70ff4cfc <+956>: jmpl   *0x7100c2a8
210   //     0x70ff4d02 <+962>: nop
211 
212   auto first_insn = insn_list->GetInstructionAtIndex(0);
213   auto second_insn = insn_list->GetInstructionAtIndex(1);
214 
215   ExecutionContext exe_ctx(m_process->GetTarget());
216   if (first_insn == nullptr || second_insn == nullptr ||
217       strcmp(first_insn->GetMnemonic(&exe_ctx), "jmpl") != 0 ||
218       strcmp(second_insn->GetMnemonic(&exe_ctx), "nop") != 0) {
219     return ThreadPlanSP();
220   }
221 
222   assert(first_insn->DoesBranch() && !second_insn->DoesBranch());
223 
224   return ThreadPlanSP(new ThreadPlanStepInstruction(
225       thread, false, false, eVoteNoOpinion, eVoteNoOpinion));
226 }
227