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(const ModuleSpec &module_spec,
66                                             lldb::addr_t module_addr) {
67   // Confusingly, there is no Target::AddSharedModule.  Instead, calling
68   // GetSharedModule() with a new module will add it to the module list and
69   // return a corresponding ModuleSP.
70   Status error;
71   ModuleSP module_sp =
72       m_process->GetTarget().GetSharedModule(module_spec, &error);
73   if (error.Fail())
74     return;
75 
76   m_loaded_modules[module_sp] = module_addr;
77   UpdateLoadedSectionsCommon(module_sp, module_addr, false);
78 }
79 
80 void DynamicLoaderWindowsDYLD::OnUnloadModule(lldb::addr_t module_addr) {
81   Address resolved_addr;
82   if (!m_process->GetTarget().ResolveLoadAddress(module_addr, resolved_addr))
83     return;
84 
85   ModuleSP module_sp = resolved_addr.GetModule();
86   if (module_sp) {
87     m_loaded_modules.erase(module_sp);
88     UnloadSectionsCommon(module_sp);
89   }
90 }
91 
92 lldb::addr_t DynamicLoaderWindowsDYLD::GetLoadAddress(ModuleSP executable) {
93   // First, see if the load address is already cached.
94   auto it = m_loaded_modules.find(executable);
95   if (it != m_loaded_modules.end() && it->second != LLDB_INVALID_ADDRESS)
96     return it->second;
97 
98   lldb::addr_t load_addr = LLDB_INVALID_ADDRESS;
99 
100   // Second, try to get it through the process plugins.  For a remote process,
101   // the remote platform will be responsible for providing it.
102   FileSpec file_spec(executable->GetPlatformFileSpec());
103   bool is_loaded = false;
104   Status status =
105       m_process->GetFileLoadAddress(file_spec, is_loaded, load_addr);
106   // Servers other than lldb server could respond with a bogus address.
107   if (status.Success() && is_loaded && load_addr != LLDB_INVALID_ADDRESS) {
108     m_loaded_modules[executable] = load_addr;
109     return load_addr;
110   }
111 
112   return LLDB_INVALID_ADDRESS;
113 }
114 
115 void DynamicLoaderWindowsDYLD::DidAttach() {
116     Log *log(GetLogIfAnyCategoriesSet(LIBLLDB_LOG_DYNAMIC_LOADER));
117   if (log)
118     log->Printf("DynamicLoaderWindowsDYLD::%s()", __FUNCTION__);
119 
120   ModuleSP executable = GetTargetExecutable();
121 
122   if (!executable.get())
123     return;
124 
125   // Try to fetch the load address of the file from the process, since there
126   // could be randomization of the load address.
127   lldb::addr_t load_addr = GetLoadAddress(executable);
128   if (load_addr == LLDB_INVALID_ADDRESS)
129     return;
130 
131   // Request the process base address.
132   lldb::addr_t image_base = m_process->GetImageInfoAddress();
133   if (image_base == load_addr)
134     return;
135 
136   // Rebase the process's modules if there is a mismatch.
137   UpdateLoadedSections(executable, LLDB_INVALID_ADDRESS, load_addr, false);
138 
139   ModuleList module_list;
140   module_list.Append(executable);
141   m_process->GetTarget().ModulesDidLoad(module_list);
142   m_process->LoadModules();
143 }
144 
145 void DynamicLoaderWindowsDYLD::DidLaunch() {
146   Log *log(GetLogIfAnyCategoriesSet(LIBLLDB_LOG_DYNAMIC_LOADER));
147   if (log)
148     log->Printf("DynamicLoaderWindowsDYLD::%s()", __FUNCTION__);
149 
150   ModuleSP executable = GetTargetExecutable();
151   if (!executable.get())
152     return;
153 
154   lldb::addr_t load_addr = GetLoadAddress(executable);
155   if (load_addr != LLDB_INVALID_ADDRESS) {
156     // Update the loaded sections so that the breakpoints can be resolved.
157     UpdateLoadedSections(executable, LLDB_INVALID_ADDRESS, load_addr, false);
158 
159     ModuleList module_list;
160     module_list.Append(executable);
161     m_process->GetTarget().ModulesDidLoad(module_list);
162     m_process->LoadModules();
163   }
164 }
165 
166 Status DynamicLoaderWindowsDYLD::CanLoadImage() { return Status(); }
167 
168 ConstString DynamicLoaderWindowsDYLD::GetPluginName() {
169   return GetPluginNameStatic();
170 }
171 
172 uint32_t DynamicLoaderWindowsDYLD::GetPluginVersion() { return 1; }
173 
174 ThreadPlanSP
175 DynamicLoaderWindowsDYLD::GetStepThroughTrampolinePlan(Thread &thread,
176                                                        bool stop) {
177   auto arch = m_process->GetTarget().GetArchitecture();
178   if (arch.GetMachine() != llvm::Triple::x86) {
179     return ThreadPlanSP();
180   }
181 
182   uint64_t pc = thread.GetRegisterContext()->GetPC();
183   // Max size of an instruction in x86 is 15 bytes.
184   AddressRange range(pc, 2 * 15);
185 
186   ExecutionContext exe_ctx(m_process->GetTarget());
187   DisassemblerSP disassembler_sp = Disassembler::DisassembleRange(
188       arch, nullptr, nullptr, exe_ctx, range, true);
189   if (!disassembler_sp) {
190     return ThreadPlanSP();
191   }
192 
193   InstructionList *insn_list = &disassembler_sp->GetInstructionList();
194   if (insn_list == nullptr) {
195     return ThreadPlanSP();
196   }
197 
198   // First instruction in a x86 Windows trampoline is going to be an indirect
199   // jump through the IAT and the next one will be a nop (usually there for
200   // alignment purposes). e.g.:
201   //     0x70ff4cfc <+956>: jmpl   *0x7100c2a8
202   //     0x70ff4d02 <+962>: nop
203 
204   auto first_insn = insn_list->GetInstructionAtIndex(0);
205   auto second_insn = insn_list->GetInstructionAtIndex(1);
206 
207   if (first_insn == nullptr || second_insn == nullptr ||
208       strcmp(first_insn->GetMnemonic(&exe_ctx), "jmpl") != 0 ||
209       strcmp(second_insn->GetMnemonic(&exe_ctx), "nop") != 0) {
210     return ThreadPlanSP();
211   }
212 
213   assert(first_insn->DoesBranch() && !second_insn->DoesBranch());
214 
215   return ThreadPlanSP(new ThreadPlanStepInstruction(
216       thread, false, false, eVoteNoOpinion, eVoteNoOpinion));
217 }
218