1 //===-- DynamicLoaderWindowsDYLD.cpp --------------------------------*- C++
2 //-*-===//
3 //
4 //                     The LLVM Compiler Infrastructure
5 //
6 // This file is distributed under the University of Illinois Open Source
7 // License. See LICENSE.TXT for details.
8 //
9 //===----------------------------------------------------------------------===//
10 
11 #include "DynamicLoaderWindowsDYLD.h"
12 
13 #include "lldb/Core/Module.h"
14 #include "lldb/Core/PluginManager.h"
15 #include "lldb/Target/ExecutionContext.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::DidAttach() {
66     Log *log(GetLogIfAnyCategoriesSet(LIBLLDB_LOG_DYNAMIC_LOADER));
67   if (log)
68     log->Printf("DynamicLoaderWindowsDYLD::%s()", __FUNCTION__);
69 
70   ModuleSP executable = GetTargetExecutable();
71 
72   if (!executable.get())
73     return;
74 
75   // Try to fetch the load address of the file from the process, since there
76   // could be randomization of the load address.
77 
78   // It might happen that the remote has a different dir for the file, so we
79   // only send the basename of the executable in the query. I think this is safe
80   // because I doubt that two executables with the same basenames are loaded in
81   // memory...
82   FileSpec file_spec(
83       executable->GetPlatformFileSpec().GetFilename().GetCString());
84   bool is_loaded;
85   addr_t base_addr = 0;
86   lldb::addr_t load_addr;
87   Status error = m_process->GetFileLoadAddress(file_spec, is_loaded, load_addr);
88   if (error.Success() && is_loaded) {
89     base_addr = load_addr;
90     UpdateLoadedSections(executable, LLDB_INVALID_ADDRESS, base_addr, false);
91   }
92 
93   ModuleList module_list;
94   module_list.Append(executable);
95   m_process->GetTarget().ModulesDidLoad(module_list);
96   m_process->LoadModules();
97 }
98 
99 void DynamicLoaderWindowsDYLD::DidLaunch() {}
100 
101 Status DynamicLoaderWindowsDYLD::CanLoadImage() { return Status(); }
102 
103 ConstString DynamicLoaderWindowsDYLD::GetPluginName() {
104   return GetPluginNameStatic();
105 }
106 
107 uint32_t DynamicLoaderWindowsDYLD::GetPluginVersion() { return 1; }
108 
109 ThreadPlanSP
110 DynamicLoaderWindowsDYLD::GetStepThroughTrampolinePlan(Thread &thread,
111                                                        bool stop) {
112   auto arch = m_process->GetTarget().GetArchitecture();
113   if (arch.GetMachine() != llvm::Triple::x86) {
114     return ThreadPlanSP();
115   }
116 
117   uint64_t pc = thread.GetRegisterContext()->GetPC();
118   // Max size of an instruction in x86 is 15 bytes.
119   AddressRange range(pc, 2 * 15);
120 
121   ExecutionContext exe_ctx(m_process->GetTarget());
122   DisassemblerSP disassembler_sp = Disassembler::DisassembleRange(
123       arch, nullptr, nullptr, exe_ctx, range, true);
124   if (!disassembler_sp) {
125     return ThreadPlanSP();
126   }
127 
128   InstructionList *insn_list = &disassembler_sp->GetInstructionList();
129   if (insn_list == nullptr) {
130     return ThreadPlanSP();
131   }
132 
133   // First instruction in a x86 Windows trampoline is going to be an indirect
134   // jump through the IAT and the next one will be a nop (usually there for
135   // alignment purposes). e.g.:
136   //     0x70ff4cfc <+956>: jmpl   *0x7100c2a8
137   //     0x70ff4d02 <+962>: nop
138 
139   auto first_insn = insn_list->GetInstructionAtIndex(0);
140   auto second_insn = insn_list->GetInstructionAtIndex(1);
141 
142   if (first_insn == nullptr || second_insn == nullptr ||
143       strcmp(first_insn->GetMnemonic(&exe_ctx), "jmpl") != 0 ||
144       strcmp(second_insn->GetMnemonic(&exe_ctx), "nop") != 0) {
145     return ThreadPlanSP();
146   }
147 
148   assert(first_insn->DoesBranch() && !second_insn->DoesBranch());
149 
150   return ThreadPlanSP(new ThreadPlanStepInstruction(
151       thread, false, false, eVoteNoOpinion, eVoteNoOpinion));
152 }
153