1 //===-- DynamicLoaderWindowsDYLD.cpp --------------------------------*- C++
2 //-*-===//
3 //
4 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
5 // See https://llvm.org/LICENSE.txt for license information.
6 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7 //
8 //===----------------------------------------------------------------------===//
9 
10 #include "DynamicLoaderWindowsDYLD.h"
11 
12 #include "lldb/Core/Module.h"
13 #include "lldb/Core/PluginManager.h"
14 #include "lldb/Target/ExecutionContext.h"
15 #include "lldb/Target/Platform.h"
16 #include "lldb/Target/Process.h"
17 #include "lldb/Target/RegisterContext.h"
18 #include "lldb/Target/Target.h"
19 #include "lldb/Target/ThreadPlanStepInstruction.h"
20 #include "lldb/Utility/Log.h"
21 
22 #include "llvm/ADT/Triple.h"
23 
24 using namespace lldb;
25 using namespace lldb_private;
26 
27 DynamicLoaderWindowsDYLD::DynamicLoaderWindowsDYLD(Process *process)
28     : DynamicLoader(process) {}
29 
30 DynamicLoaderWindowsDYLD::~DynamicLoaderWindowsDYLD() {}
31 
32 void DynamicLoaderWindowsDYLD::Initialize() {
33   PluginManager::RegisterPlugin(GetPluginNameStatic(),
34                                 GetPluginDescriptionStatic(), CreateInstance);
35 }
36 
37 void DynamicLoaderWindowsDYLD::Terminate() {}
38 
39 ConstString DynamicLoaderWindowsDYLD::GetPluginNameStatic() {
40   static ConstString g_plugin_name("windows-dyld");
41   return g_plugin_name;
42 }
43 
44 const char *DynamicLoaderWindowsDYLD::GetPluginDescriptionStatic() {
45   return "Dynamic loader plug-in that watches for shared library "
46          "loads/unloads in Windows processes.";
47 }
48 
49 DynamicLoader *DynamicLoaderWindowsDYLD::CreateInstance(Process *process,
50                                                         bool force) {
51   bool should_create = force;
52   if (!should_create) {
53     const llvm::Triple &triple_ref =
54         process->GetTarget().GetArchitecture().GetTriple();
55     if (triple_ref.getOS() == llvm::Triple::Win32)
56       should_create = true;
57   }
58 
59   if (should_create)
60     return new DynamicLoaderWindowsDYLD(process);
61 
62   return nullptr;
63 }
64 
65 void DynamicLoaderWindowsDYLD::OnLoadModule(lldb::ModuleSP module_sp,
66                                             const ModuleSpec module_spec,
67                                             lldb::addr_t module_addr) {
68 
69   // Resolve the module unless we already have one.
70   if (!module_sp) {
71     // Confusingly, there is no Target::AddSharedModule.  Instead, calling
72     // GetSharedModule() with a new module will add it to the module list and
73     // return a corresponding ModuleSP.
74     Status error;
75     module_sp = m_process->GetTarget().GetSharedModule(module_spec, &error);
76     if (error.Fail())
77       return;
78   }
79 
80   m_loaded_modules[module_sp] = module_addr;
81   UpdateLoadedSectionsCommon(module_sp, module_addr, false);
82   ModuleList module_list;
83   module_list.Append(module_sp);
84   m_process->GetTarget().ModulesDidLoad(module_list);
85 }
86 
87 void DynamicLoaderWindowsDYLD::OnUnloadModule(lldb::addr_t module_addr) {
88   Address resolved_addr;
89   if (!m_process->GetTarget().ResolveLoadAddress(module_addr, resolved_addr))
90     return;
91 
92   ModuleSP module_sp = resolved_addr.GetModule();
93   if (module_sp) {
94     m_loaded_modules.erase(module_sp);
95     UnloadSectionsCommon(module_sp);
96     ModuleList module_list;
97     module_list.Append(module_sp);
98     m_process->GetTarget().ModulesDidUnload(module_list, false);
99   }
100 }
101 
102 lldb::addr_t DynamicLoaderWindowsDYLD::GetLoadAddress(ModuleSP executable) {
103   // First, see if the load address is already cached.
104   auto it = m_loaded_modules.find(executable);
105   if (it != m_loaded_modules.end() && it->second != LLDB_INVALID_ADDRESS)
106     return it->second;
107 
108   lldb::addr_t load_addr = LLDB_INVALID_ADDRESS;
109 
110   // Second, try to get it through the process plugins.  For a remote process,
111   // the remote platform will be responsible for providing it.
112   FileSpec file_spec(executable->GetPlatformFileSpec());
113   bool is_loaded = false;
114   Status status =
115       m_process->GetFileLoadAddress(file_spec, is_loaded, load_addr);
116   // Servers other than lldb server could respond with a bogus address.
117   if (status.Success() && is_loaded && load_addr != LLDB_INVALID_ADDRESS) {
118     m_loaded_modules[executable] = load_addr;
119     return load_addr;
120   }
121 
122   return LLDB_INVALID_ADDRESS;
123 }
124 
125 void DynamicLoaderWindowsDYLD::DidAttach() {
126     Log *log(GetLogIfAnyCategoriesSet(LIBLLDB_LOG_DYNAMIC_LOADER));
127   if (log)
128     log->Printf("DynamicLoaderWindowsDYLD::%s()", __FUNCTION__);
129 
130   ModuleSP executable = GetTargetExecutable();
131 
132   if (!executable.get())
133     return;
134 
135   // Try to fetch the load address of the file from the process, since there
136   // could be randomization of the load address.
137   lldb::addr_t load_addr = GetLoadAddress(executable);
138   if (load_addr == LLDB_INVALID_ADDRESS)
139     return;
140 
141   // Request the process base address.
142   lldb::addr_t image_base = m_process->GetImageInfoAddress();
143   if (image_base == load_addr)
144     return;
145 
146   // Rebase the process's modules if there is a mismatch.
147   UpdateLoadedSections(executable, LLDB_INVALID_ADDRESS, load_addr, false);
148 
149   ModuleList module_list;
150   module_list.Append(executable);
151   m_process->GetTarget().ModulesDidLoad(module_list);
152   m_process->LoadModules();
153 }
154 
155 void DynamicLoaderWindowsDYLD::DidLaunch() {
156   Log *log(GetLogIfAnyCategoriesSet(LIBLLDB_LOG_DYNAMIC_LOADER));
157   if (log)
158     log->Printf("DynamicLoaderWindowsDYLD::%s()", __FUNCTION__);
159 
160   ModuleSP executable = GetTargetExecutable();
161   if (!executable.get())
162     return;
163 
164   lldb::addr_t load_addr = GetLoadAddress(executable);
165   if (load_addr != LLDB_INVALID_ADDRESS) {
166     // Update the loaded sections so that the breakpoints can be resolved.
167     UpdateLoadedSections(executable, LLDB_INVALID_ADDRESS, load_addr, false);
168 
169     ModuleList module_list;
170     module_list.Append(executable);
171     m_process->GetTarget().ModulesDidLoad(module_list);
172     m_process->LoadModules();
173   }
174 }
175 
176 Status DynamicLoaderWindowsDYLD::CanLoadImage() { return Status(); }
177 
178 ConstString DynamicLoaderWindowsDYLD::GetPluginName() {
179   return GetPluginNameStatic();
180 }
181 
182 uint32_t DynamicLoaderWindowsDYLD::GetPluginVersion() { return 1; }
183 
184 ThreadPlanSP
185 DynamicLoaderWindowsDYLD::GetStepThroughTrampolinePlan(Thread &thread,
186                                                        bool stop) {
187   auto arch = m_process->GetTarget().GetArchitecture();
188   if (arch.GetMachine() != llvm::Triple::x86) {
189     return ThreadPlanSP();
190   }
191 
192   uint64_t pc = thread.GetRegisterContext()->GetPC();
193   // Max size of an instruction in x86 is 15 bytes.
194   AddressRange range(pc, 2 * 15);
195 
196   ExecutionContext exe_ctx(m_process->GetTarget());
197   DisassemblerSP disassembler_sp = Disassembler::DisassembleRange(
198       arch, nullptr, nullptr, exe_ctx, range, true);
199   if (!disassembler_sp) {
200     return ThreadPlanSP();
201   }
202 
203   InstructionList *insn_list = &disassembler_sp->GetInstructionList();
204   if (insn_list == nullptr) {
205     return ThreadPlanSP();
206   }
207 
208   // First instruction in a x86 Windows trampoline is going to be an indirect
209   // jump through the IAT and the next one will be a nop (usually there for
210   // alignment purposes). e.g.:
211   //     0x70ff4cfc <+956>: jmpl   *0x7100c2a8
212   //     0x70ff4d02 <+962>: nop
213 
214   auto first_insn = insn_list->GetInstructionAtIndex(0);
215   auto second_insn = insn_list->GetInstructionAtIndex(1);
216 
217   if (first_insn == nullptr || second_insn == nullptr ||
218       strcmp(first_insn->GetMnemonic(&exe_ctx), "jmpl") != 0 ||
219       strcmp(second_insn->GetMnemonic(&exe_ctx), "nop") != 0) {
220     return ThreadPlanSP();
221   }
222 
223   assert(first_insn->DoesBranch() && !second_insn->DoesBranch());
224 
225   return ThreadPlanSP(new ThreadPlanStepInstruction(
226       thread, false, false, eVoteNoOpinion, eVoteNoOpinion));
227 }
228