1 //===-- DynamicLoaderPOSIX.h ------------------------------------*- C++ -*-===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 
10 // C Includes
11 // C++ Includes
12 // Other libraries and framework includes
13 #include "lldb/Core/PluginManager.h"
14 #include "lldb/Core/Log.h"
15 #include "lldb/Core/Module.h"
16 #include "lldb/Core/ModuleSpec.h"
17 #include "lldb/Core/Section.h"
18 #include "lldb/Symbol/ObjectFile.h"
19 #include "lldb/Target/Process.h"
20 #include "lldb/Target/Target.h"
21 #include "lldb/Target/Thread.h"
22 #include "lldb/Target/ThreadPlanRunToAddress.h"
23 
24 #include "AuxVector.h"
25 #include "DynamicLoaderPOSIXDYLD.h"
26 
27 using namespace lldb;
28 using namespace lldb_private;
29 
30 void
31 DynamicLoaderPOSIXDYLD::Initialize()
32 {
33     PluginManager::RegisterPlugin(GetPluginNameStatic(),
34                                   GetPluginDescriptionStatic(),
35                                   CreateInstance);
36 }
37 
38 void
39 DynamicLoaderPOSIXDYLD::Terminate()
40 {
41 }
42 
43 lldb_private::ConstString
44 DynamicLoaderPOSIXDYLD::GetPluginName()
45 {
46     return GetPluginNameStatic();
47 }
48 
49 lldb_private::ConstString
50 DynamicLoaderPOSIXDYLD::GetPluginNameStatic()
51 {
52     static ConstString g_name("linux-dyld");
53     return g_name;
54 }
55 
56 const char *
57 DynamicLoaderPOSIXDYLD::GetPluginDescriptionStatic()
58 {
59     return "Dynamic loader plug-in that watches for shared library "
60            "loads/unloads in POSIX processes.";
61 }
62 
63 void
64 DynamicLoaderPOSIXDYLD::GetPluginCommandHelp(const char *command, Stream *strm)
65 {
66 }
67 
68 uint32_t
69 DynamicLoaderPOSIXDYLD::GetPluginVersion()
70 {
71     return 1;
72 }
73 
74 DynamicLoader *
75 DynamicLoaderPOSIXDYLD::CreateInstance(Process *process, bool force)
76 {
77     bool create = force;
78     if (!create)
79     {
80         const llvm::Triple &triple_ref = process->GetTarget().GetArchitecture().GetTriple();
81         if (triple_ref.getOS() == llvm::Triple::Linux ||
82             triple_ref.getOS() == llvm::Triple::FreeBSD)
83             create = true;
84     }
85 
86     if (create)
87         return new DynamicLoaderPOSIXDYLD (process);
88     return NULL;
89 }
90 
91 DynamicLoaderPOSIXDYLD::DynamicLoaderPOSIXDYLD(Process *process)
92     : DynamicLoader(process),
93       m_rendezvous(process),
94       m_load_offset(LLDB_INVALID_ADDRESS),
95       m_entry_point(LLDB_INVALID_ADDRESS),
96       m_auxv()
97 {
98 }
99 
100 DynamicLoaderPOSIXDYLD::~DynamicLoaderPOSIXDYLD()
101 {
102 }
103 
104 void
105 DynamicLoaderPOSIXDYLD::DidAttach()
106 {
107     ModuleSP executable;
108     addr_t load_offset;
109 
110     m_auxv.reset(new AuxVector(m_process));
111 
112     executable = GetTargetExecutable();
113     load_offset = ComputeLoadOffset();
114 
115     if (executable.get() && load_offset != LLDB_INVALID_ADDRESS)
116     {
117         ModuleList module_list;
118         module_list.Append(executable);
119         UpdateLoadedSections(executable, load_offset);
120         LoadAllCurrentModules();
121         m_process->GetTarget().ModulesDidLoad(module_list);
122     }
123 }
124 
125 void
126 DynamicLoaderPOSIXDYLD::DidLaunch()
127 {
128     ModuleSP executable;
129     addr_t load_offset;
130 
131     m_auxv.reset(new AuxVector(m_process));
132 
133     executable = GetTargetExecutable();
134     load_offset = ComputeLoadOffset();
135 
136     if (executable.get() && load_offset != LLDB_INVALID_ADDRESS)
137     {
138         ModuleList module_list;
139         module_list.Append(executable);
140         UpdateLoadedSections(executable, load_offset);
141         ProbeEntry();
142         m_process->GetTarget().ModulesDidLoad(module_list);
143     }
144 }
145 
146 ModuleSP
147 DynamicLoaderPOSIXDYLD::GetTargetExecutable()
148 {
149     Target &target = m_process->GetTarget();
150     ModuleSP executable = target.GetExecutableModule();
151 
152     if (executable.get())
153     {
154         if (executable->GetFileSpec().Exists())
155         {
156             ModuleSpec module_spec (executable->GetFileSpec(), executable->GetArchitecture());
157             ModuleSP module_sp (new Module (module_spec));
158 
159             // Check if the executable has changed and set it to the target executable if they differ.
160             if (module_sp.get() && module_sp->GetUUID().IsValid() && executable->GetUUID().IsValid())
161             {
162                 if (module_sp->GetUUID() != executable->GetUUID())
163                     executable.reset();
164             }
165             else if (executable->FileHasChanged())
166             {
167                 executable.reset();
168             }
169 
170             if (!executable.get())
171             {
172                 executable = target.GetSharedModule(module_spec);
173                 if (executable.get() != target.GetExecutableModulePointer())
174                 {
175                     // Don't load dependent images since we are in dyld where we will know
176                     // and find out about all images that are loaded
177                     const bool get_dependent_images = false;
178                     target.SetExecutableModule(executable, get_dependent_images);
179                 }
180             }
181         }
182     }
183     return executable;
184 }
185 
186 Error
187 DynamicLoaderPOSIXDYLD::ExecutePluginCommand(Args &command, Stream *strm)
188 {
189     return Error();
190 }
191 
192 Log *
193 DynamicLoaderPOSIXDYLD::EnablePluginLogging(Stream *strm, Args &command)
194 {
195     return NULL;
196 }
197 
198 Error
199 DynamicLoaderPOSIXDYLD::CanLoadImage()
200 {
201     return Error();
202 }
203 
204 void
205 DynamicLoaderPOSIXDYLD::UpdateLoadedSections(ModuleSP module, addr_t base_addr)
206 {
207     ObjectFile *obj_file = module->GetObjectFile();
208     SectionList *sections = obj_file->GetSectionList();
209     SectionLoadList &load_list = m_process->GetTarget().GetSectionLoadList();
210     const size_t num_sections = sections->GetSize();
211 
212     for (unsigned i = 0; i < num_sections; ++i)
213     {
214         SectionSP section_sp (sections->GetSectionAtIndex(i));
215         lldb::addr_t new_load_addr = section_sp->GetFileAddress() + base_addr;
216         lldb::addr_t old_load_addr = load_list.GetSectionLoadAddress(section_sp);
217 
218         // If the file address of the section is zero then this is not an
219         // allocatable/loadable section (property of ELF sh_addr).  Skip it.
220         if (new_load_addr == base_addr)
221             continue;
222 
223         if (old_load_addr == LLDB_INVALID_ADDRESS ||
224             old_load_addr != new_load_addr)
225             load_list.SetSectionLoadAddress(section_sp, new_load_addr);
226     }
227 }
228 
229 void
230 DynamicLoaderPOSIXDYLD::ProbeEntry()
231 {
232     Breakpoint *entry_break;
233     addr_t entry;
234 
235     if ((entry = GetEntryPoint()) == LLDB_INVALID_ADDRESS)
236         return;
237 
238     entry_break = m_process->GetTarget().CreateBreakpoint(entry, true).get();
239     entry_break->SetCallback(EntryBreakpointHit, this, true);
240     entry_break->SetBreakpointKind("shared-library-event");
241 }
242 
243 // The runtime linker has run and initialized the rendezvous structure once the
244 // process has hit its entry point.  When we hit the corresponding breakpoint we
245 // interrogate the rendezvous structure to get the load addresses of all
246 // dependent modules for the process.  Similarly, we can discover the runtime
247 // linker function and setup a breakpoint to notify us of any dynamically loaded
248 // modules (via dlopen).
249 bool
250 DynamicLoaderPOSIXDYLD::EntryBreakpointHit(void *baton,
251                                            StoppointCallbackContext *context,
252                                            user_id_t break_id,
253                                            user_id_t break_loc_id)
254 {
255     DynamicLoaderPOSIXDYLD* dyld_instance;
256 
257     dyld_instance = static_cast<DynamicLoaderPOSIXDYLD*>(baton);
258     dyld_instance->LoadAllCurrentModules();
259     dyld_instance->SetRendezvousBreakpoint();
260     return false; // Continue running.
261 }
262 
263 void
264 DynamicLoaderPOSIXDYLD::SetRendezvousBreakpoint()
265 {
266     Breakpoint *dyld_break;
267     addr_t break_addr;
268 
269     break_addr = m_rendezvous.GetBreakAddress();
270     dyld_break = m_process->GetTarget().CreateBreakpoint(break_addr, true).get();
271     dyld_break->SetCallback(RendezvousBreakpointHit, this, true);
272     dyld_break->SetBreakpointKind ("shared-library-event");
273 }
274 
275 bool
276 DynamicLoaderPOSIXDYLD::RendezvousBreakpointHit(void *baton,
277                                                 StoppointCallbackContext *context,
278                                                 user_id_t break_id,
279                                                 user_id_t break_loc_id)
280 {
281     DynamicLoaderPOSIXDYLD* dyld_instance;
282 
283     dyld_instance = static_cast<DynamicLoaderPOSIXDYLD*>(baton);
284     dyld_instance->RefreshModules();
285 
286     // Return true to stop the target, false to just let the target run.
287     return dyld_instance->GetStopWhenImagesChange();
288 }
289 
290 void
291 DynamicLoaderPOSIXDYLD::RefreshModules()
292 {
293     if (!m_rendezvous.Resolve())
294         return;
295 
296     DYLDRendezvous::iterator I;
297     DYLDRendezvous::iterator E;
298 
299     ModuleList &loaded_modules = m_process->GetTarget().GetImages();
300 
301     if (m_rendezvous.ModulesDidLoad())
302     {
303         ModuleList new_modules;
304 
305         E = m_rendezvous.loaded_end();
306         for (I = m_rendezvous.loaded_begin(); I != E; ++I)
307         {
308             FileSpec file(I->path.c_str(), true);
309             ModuleSP module_sp = LoadModuleAtAddress(file, I->base_addr);
310             if (module_sp.get())
311                 loaded_modules.AppendIfNeeded(module_sp);
312         }
313     }
314 
315     if (m_rendezvous.ModulesDidUnload())
316     {
317         ModuleList old_modules;
318 
319         E = m_rendezvous.unloaded_end();
320         for (I = m_rendezvous.unloaded_begin(); I != E; ++I)
321         {
322             FileSpec file(I->path.c_str(), true);
323             ModuleSpec module_spec (file);
324             ModuleSP module_sp =
325                 loaded_modules.FindFirstModule (module_spec);
326             if (module_sp.get())
327                 old_modules.Append(module_sp);
328         }
329         loaded_modules.Remove(old_modules);
330     }
331 }
332 
333 ThreadPlanSP
334 DynamicLoaderPOSIXDYLD::GetStepThroughTrampolinePlan(Thread &thread, bool stop)
335 {
336     ThreadPlanSP thread_plan_sp;
337 
338     StackFrame *frame = thread.GetStackFrameAtIndex(0).get();
339     const SymbolContext &context = frame->GetSymbolContext(eSymbolContextSymbol);
340     Symbol *sym = context.symbol;
341 
342     if (sym == NULL || !sym->IsTrampoline())
343         return thread_plan_sp;
344 
345     const ConstString &sym_name = sym->GetMangled().GetName(Mangled::ePreferMangled);
346     if (!sym_name)
347         return thread_plan_sp;
348 
349     SymbolContextList target_symbols;
350     Target &target = thread.GetProcess()->GetTarget();
351     const ModuleList &images = target.GetImages();
352 
353     images.FindSymbolsWithNameAndType(sym_name, eSymbolTypeCode, target_symbols);
354     size_t num_targets = target_symbols.GetSize();
355     if (!num_targets)
356         return thread_plan_sp;
357 
358     typedef std::vector<lldb::addr_t> AddressVector;
359     AddressVector addrs;
360     for (size_t i = 0; i < num_targets; ++i)
361     {
362         SymbolContext context;
363         AddressRange range;
364         if (target_symbols.GetContextAtIndex(i, context))
365         {
366             context.GetAddressRange(eSymbolContextEverything, 0, false, range);
367             lldb::addr_t addr = range.GetBaseAddress().GetLoadAddress(&target);
368             if (addr != LLDB_INVALID_ADDRESS)
369                 addrs.push_back(addr);
370         }
371     }
372 
373     if (addrs.size() > 0)
374     {
375         AddressVector::iterator start = addrs.begin();
376         AddressVector::iterator end = addrs.end();
377 
378         std::sort(start, end);
379         addrs.erase(std::unique(start, end), end);
380         thread_plan_sp.reset(new ThreadPlanRunToAddress(thread, addrs, stop));
381     }
382 
383     return thread_plan_sp;
384 }
385 
386 void
387 DynamicLoaderPOSIXDYLD::LoadAllCurrentModules()
388 {
389     DYLDRendezvous::iterator I;
390     DYLDRendezvous::iterator E;
391     ModuleList module_list;
392 
393     if (!m_rendezvous.Resolve())
394         return;
395 
396     for (I = m_rendezvous.begin(), E = m_rendezvous.end(); I != E; ++I)
397     {
398         FileSpec file(I->path.c_str(), false);
399         ModuleSP module_sp = LoadModuleAtAddress(file, I->base_addr);
400         if (module_sp.get())
401             module_list.Append(module_sp);
402     }
403 
404     m_process->GetTarget().ModulesDidLoad(module_list);
405 }
406 
407 ModuleSP
408 DynamicLoaderPOSIXDYLD::LoadModuleAtAddress(const FileSpec &file, addr_t base_addr)
409 {
410     Target &target = m_process->GetTarget();
411     ModuleList &modules = target.GetImages();
412     ModuleSP module_sp;
413 
414     ModuleSpec module_spec (file, target.GetArchitecture());
415     if ((module_sp = modules.FindFirstModule (module_spec)))
416     {
417         UpdateLoadedSections(module_sp, base_addr);
418     }
419     else if ((module_sp = target.GetSharedModule(module_spec)))
420     {
421         UpdateLoadedSections(module_sp, base_addr);
422     }
423 
424     return module_sp;
425 }
426 
427 addr_t
428 DynamicLoaderPOSIXDYLD::ComputeLoadOffset()
429 {
430     addr_t virt_entry;
431 
432     if (m_load_offset != LLDB_INVALID_ADDRESS)
433         return m_load_offset;
434 
435     if ((virt_entry = GetEntryPoint()) == LLDB_INVALID_ADDRESS)
436         return LLDB_INVALID_ADDRESS;
437 
438     ModuleSP module = m_process->GetTarget().GetExecutableModule();
439     ObjectFile *exe = module->GetObjectFile();
440     Address file_entry = exe->GetEntryPointAddress();
441 
442     if (!file_entry.IsValid())
443         return LLDB_INVALID_ADDRESS;
444 
445     m_load_offset = virt_entry - file_entry.GetFileAddress();
446     return m_load_offset;
447 }
448 
449 addr_t
450 DynamicLoaderPOSIXDYLD::GetEntryPoint()
451 {
452     if (m_entry_point != LLDB_INVALID_ADDRESS)
453         return m_entry_point;
454 
455     if (m_auxv.get() == NULL)
456         return LLDB_INVALID_ADDRESS;
457 
458     AuxVector::iterator I = m_auxv->FindEntry(AuxVector::AT_ENTRY);
459 
460     if (I == m_auxv->end())
461         return LLDB_INVALID_ADDRESS;
462 
463     m_entry_point = static_cast<addr_t>(I->value);
464     return m_entry_point;
465 }
466