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 #include "lldb/Breakpoint/BreakpointLocation.h"
24 
25 #include "AuxVector.h"
26 #include "DynamicLoaderPOSIXDYLD.h"
27 
28 using namespace lldb;
29 using namespace lldb_private;
30 
31 void
32 DynamicLoaderPOSIXDYLD::Initialize()
33 {
34     PluginManager::RegisterPlugin(GetPluginNameStatic(),
35                                   GetPluginDescriptionStatic(),
36                                   CreateInstance);
37 }
38 
39 void
40 DynamicLoaderPOSIXDYLD::Terminate()
41 {
42 }
43 
44 lldb_private::ConstString
45 DynamicLoaderPOSIXDYLD::GetPluginName()
46 {
47     return GetPluginNameStatic();
48 }
49 
50 lldb_private::ConstString
51 DynamicLoaderPOSIXDYLD::GetPluginNameStatic()
52 {
53     static ConstString g_name("linux-dyld");
54     return g_name;
55 }
56 
57 const char *
58 DynamicLoaderPOSIXDYLD::GetPluginDescriptionStatic()
59 {
60     return "Dynamic loader plug-in that watches for shared library "
61            "loads/unloads in POSIX processes.";
62 }
63 
64 void
65 DynamicLoaderPOSIXDYLD::GetPluginCommandHelp(const char *command, Stream *strm)
66 {
67 }
68 
69 uint32_t
70 DynamicLoaderPOSIXDYLD::GetPluginVersion()
71 {
72     return 1;
73 }
74 
75 DynamicLoader *
76 DynamicLoaderPOSIXDYLD::CreateInstance(Process *process, bool force)
77 {
78     bool create = force;
79     if (!create)
80     {
81         const llvm::Triple &triple_ref = process->GetTarget().GetArchitecture().GetTriple();
82         if (triple_ref.getOS() == llvm::Triple::Linux ||
83             triple_ref.getOS() == llvm::Triple::FreeBSD)
84             create = true;
85     }
86 
87     if (create)
88         return new DynamicLoaderPOSIXDYLD (process);
89     return NULL;
90 }
91 
92 DynamicLoaderPOSIXDYLD::DynamicLoaderPOSIXDYLD(Process *process)
93     : DynamicLoader(process),
94       m_rendezvous(process),
95       m_load_offset(LLDB_INVALID_ADDRESS),
96       m_entry_point(LLDB_INVALID_ADDRESS),
97       m_auxv(),
98       m_dyld_bid(LLDB_INVALID_BREAK_ID)
99 {
100 }
101 
102 DynamicLoaderPOSIXDYLD::~DynamicLoaderPOSIXDYLD()
103 {
104     if (m_dyld_bid != LLDB_INVALID_BREAK_ID)
105     {
106         m_process->GetTarget().RemoveBreakpointByID (m_dyld_bid);
107         m_dyld_bid = LLDB_INVALID_BREAK_ID;
108     }
109 }
110 
111 void
112 DynamicLoaderPOSIXDYLD::DidAttach()
113 {
114     Log *log (GetLogIfAnyCategoriesSet(LIBLLDB_LOG_DYNAMIC_LOADER));
115     ModuleSP executable_sp;
116     addr_t load_offset;
117 
118     if (log)
119         log->Printf ("DynamicLoaderPOSIXDYLD::%s() pid %" PRIu64, __FUNCTION__, m_process ? m_process->GetID () : LLDB_INVALID_PROCESS_ID);
120 
121     m_auxv.reset(new AuxVector(m_process));
122     if (log)
123         log->Printf ("DynamicLoaderPOSIXDYLD::%s pid %" PRIu64 " reloaded auxv data", __FUNCTION__, m_process ? m_process->GetID () : LLDB_INVALID_PROCESS_ID);
124 
125     executable_sp = GetTargetExecutable();
126     load_offset = ComputeLoadOffset();
127     if (log)
128         log->Printf ("DynamicLoaderPOSIXDYLD::%s pid %" PRIu64 " executable '%s', load_offset 0x%" PRIx64, __FUNCTION__, m_process ? m_process->GetID () : LLDB_INVALID_PROCESS_ID, executable_sp ? executable_sp->GetFileSpec().GetPath().c_str () : "<null executable>", load_offset);
129 
130 
131     if (executable_sp && load_offset != LLDB_INVALID_ADDRESS)
132     {
133         ModuleList module_list;
134 
135         module_list.Append(executable_sp);
136         if (log)
137             log->Printf ("DynamicLoaderPOSIXDYLD::%s pid %" PRIu64 " added executable '%s' to module load list",
138                          __FUNCTION__,
139                          m_process ? m_process->GetID () : LLDB_INVALID_PROCESS_ID,
140                          executable_sp->GetFileSpec().GetPath().c_str ());
141 
142         UpdateLoadedSections(executable_sp, LLDB_INVALID_ADDRESS, load_offset);
143 
144         // When attaching to a target, there are two possible states:
145         // (1) We already crossed the entry point and therefore the rendezvous
146         //     structure is ready to be used and we can load the list of modules
147         //     and place the rendezvous breakpoint.
148         // (2) We didn't cross the entry point yet, so these structures are not
149         //     ready; we should behave as if we just launched the target and
150         //     call ProbeEntry(). This will place a breakpoint on the entry
151         //     point which itself will be hit after the rendezvous structure is
152         //     set up and will perform actions described in (1).
153         if (m_rendezvous.Resolve())
154         {
155             if (log)
156                 log->Printf ("DynamicLoaderPOSIXDYLD::%s() pid %" PRIu64 " rendezvous could resolve: attach assuming dynamic loader info is available now", __FUNCTION__, m_process ? m_process->GetID () : LLDB_INVALID_PROCESS_ID);
157             LoadAllCurrentModules();
158             SetRendezvousBreakpoint();
159         }
160         else
161         {
162             if (log)
163                 log->Printf ("DynamicLoaderPOSIXDYLD::%s() pid %" PRIu64 " rendezvous could not yet resolve: adding breakpoint to catch future rendezvous setup", __FUNCTION__, m_process ? m_process->GetID () : LLDB_INVALID_PROCESS_ID);
164             ProbeEntry();
165         }
166 
167         m_process->GetTarget().ModulesDidLoad(module_list);
168         if (log)
169         {
170             log->Printf ("DynamicLoaderPOSIXDYLD::%s told the target about the modules that loaded:", __FUNCTION__);
171             for (auto module_sp : module_list.Modules ())
172             {
173                 log->Printf ("-- [module] %s (pid %" PRIu64 ")",
174                              module_sp ? module_sp->GetFileSpec().GetPath().c_str () : "<null>",
175                              m_process ? m_process->GetID () : LLDB_INVALID_PROCESS_ID);
176             }
177         }
178     }
179 }
180 
181 void
182 DynamicLoaderPOSIXDYLD::DidLaunch()
183 {
184     Log *log (GetLogIfAnyCategoriesSet(LIBLLDB_LOG_DYNAMIC_LOADER));
185     if (log)
186         log->Printf ("DynamicLoaderPOSIXDYLD::%s()", __FUNCTION__);
187 
188     ModuleSP executable;
189     addr_t load_offset;
190 
191     m_auxv.reset(new AuxVector(m_process));
192 
193     executable = GetTargetExecutable();
194     load_offset = ComputeLoadOffset();
195 
196     if (executable.get() && load_offset != LLDB_INVALID_ADDRESS)
197     {
198         ModuleList module_list;
199         module_list.Append(executable);
200         UpdateLoadedSections(executable, LLDB_INVALID_ADDRESS, load_offset);
201 
202         if (log)
203             log->Printf ("DynamicLoaderPOSIXDYLD::%s about to call ProbeEntry()", __FUNCTION__);
204         ProbeEntry();
205 
206         m_process->GetTarget().ModulesDidLoad(module_list);
207     }
208 }
209 
210 Error
211 DynamicLoaderPOSIXDYLD::ExecutePluginCommand(Args &command, Stream *strm)
212 {
213     return Error();
214 }
215 
216 Log *
217 DynamicLoaderPOSIXDYLD::EnablePluginLogging(Stream *strm, Args &command)
218 {
219     return NULL;
220 }
221 
222 Error
223 DynamicLoaderPOSIXDYLD::CanLoadImage()
224 {
225     return Error();
226 }
227 
228 void
229 DynamicLoaderPOSIXDYLD::UpdateLoadedSections(ModuleSP module, addr_t link_map_addr, addr_t base_addr)
230 {
231     m_loaded_modules[module] = link_map_addr;
232 
233     UpdateLoadedSectionsCommon(module, base_addr);
234 }
235 
236 void
237 DynamicLoaderPOSIXDYLD::UnloadSections(const ModuleSP module)
238 {
239     m_loaded_modules.erase(module);
240 
241     UnloadSectionsCommon(module);
242 }
243 
244 void
245 DynamicLoaderPOSIXDYLD::ProbeEntry()
246 {
247     Log *log (GetLogIfAnyCategoriesSet(LIBLLDB_LOG_DYNAMIC_LOADER));
248 
249     const addr_t entry = GetEntryPoint();
250     if (entry == LLDB_INVALID_ADDRESS)
251     {
252         if (log)
253             log->Printf ("DynamicLoaderPOSIXDYLD::%s pid %" PRIu64 " GetEntryPoint() returned no address, not setting entry breakpoint", __FUNCTION__, m_process ? m_process->GetID () : LLDB_INVALID_PROCESS_ID);
254         return;
255     }
256 
257     if (log)
258         log->Printf ("DynamicLoaderPOSIXDYLD::%s pid %" PRIu64 " GetEntryPoint() returned address 0x%" PRIx64 ", setting entry breakpoint", __FUNCTION__, m_process ? m_process->GetID () : LLDB_INVALID_PROCESS_ID, entry);
259 
260 
261     Breakpoint *const entry_break = m_process->GetTarget().CreateBreakpoint(entry, true, false).get();
262     entry_break->SetCallback(EntryBreakpointHit, this, true);
263     entry_break->SetBreakpointKind("shared-library-event");
264 
265     // Shoudn't hit this more than once.
266     entry_break->SetOneShot (true);
267 }
268 
269 // The runtime linker has run and initialized the rendezvous structure once the
270 // process has hit its entry point.  When we hit the corresponding breakpoint we
271 // interrogate the rendezvous structure to get the load addresses of all
272 // dependent modules for the process.  Similarly, we can discover the runtime
273 // linker function and setup a breakpoint to notify us of any dynamically loaded
274 // modules (via dlopen).
275 bool
276 DynamicLoaderPOSIXDYLD::EntryBreakpointHit(void *baton,
277                                            StoppointCallbackContext *context,
278                                            user_id_t break_id,
279                                            user_id_t break_loc_id)
280 {
281     assert(baton && "null baton");
282     if (!baton)
283         return false;
284 
285     Log *log (GetLogIfAnyCategoriesSet(LIBLLDB_LOG_DYNAMIC_LOADER));
286     DynamicLoaderPOSIXDYLD *const dyld_instance = static_cast<DynamicLoaderPOSIXDYLD*>(baton);
287     if (log)
288         log->Printf ("DynamicLoaderPOSIXDYLD::%s called for pid %" PRIu64, __FUNCTION__, dyld_instance->m_process ? dyld_instance->m_process->GetID () : LLDB_INVALID_PROCESS_ID);
289 
290     // Disable the breakpoint --- if a stop happens right after this, which we've seen on occasion, we don't
291     // want the breakpoint stepping thread-plan logic to show a breakpoint instruction at the disassembled
292     // entry point to the program.  Disabling it prevents it.  (One-shot is not enough - one-shot removal logic
293     // only happens after the breakpoint goes public, which wasn't happening in our scenario).
294     if (dyld_instance->m_process)
295     {
296         BreakpointSP breakpoint_sp = dyld_instance->m_process->GetTarget().GetBreakpointByID (break_id);
297         if (breakpoint_sp)
298         {
299             if (log)
300                 log->Printf ("DynamicLoaderPOSIXDYLD::%s pid %" PRIu64 " disabling breakpoint id %" PRIu64, __FUNCTION__, dyld_instance->m_process->GetID (), break_id);
301             breakpoint_sp->SetEnabled (false);
302         }
303         else
304         {
305             if (log)
306                 log->Printf ("DynamicLoaderPOSIXDYLD::%s pid %" PRIu64 " failed to find breakpoint for breakpoint id %" PRIu64, __FUNCTION__, dyld_instance->m_process->GetID (), break_id);
307         }
308     }
309     else
310     {
311         if (log)
312             log->Printf ("DynamicLoaderPOSIXDYLD::%s breakpoint id %" PRIu64 " no Process instance!  Cannot disable breakpoint", __FUNCTION__, break_id);
313     }
314 
315     dyld_instance->LoadAllCurrentModules();
316     dyld_instance->SetRendezvousBreakpoint();
317     return false; // Continue running.
318 }
319 
320 void
321 DynamicLoaderPOSIXDYLD::SetRendezvousBreakpoint()
322 {
323     Log *log (GetLogIfAnyCategoriesSet(LIBLLDB_LOG_DYNAMIC_LOADER));
324 
325     addr_t break_addr = m_rendezvous.GetBreakAddress();
326     Target &target = m_process->GetTarget();
327 
328     if (m_dyld_bid == LLDB_INVALID_BREAK_ID)
329     {
330         if (log)
331             log->Printf ("DynamicLoaderPOSIXDYLD::%s pid %" PRIu64 " setting rendezvous break address at 0x%" PRIx64, __FUNCTION__, m_process ? m_process->GetID () : LLDB_INVALID_PROCESS_ID, break_addr);
332         Breakpoint *dyld_break = target.CreateBreakpoint (break_addr, true, false).get();
333         dyld_break->SetCallback(RendezvousBreakpointHit, this, true);
334         dyld_break->SetBreakpointKind ("shared-library-event");
335         m_dyld_bid = dyld_break->GetID();
336     }
337     else
338     {
339         if (log)
340             log->Printf ("DynamicLoaderPOSIXDYLD::%s pid %" PRIu64 " reusing break id %" PRIu32 ", address at 0x%" PRIx64, __FUNCTION__, m_process ? m_process->GetID () : LLDB_INVALID_PROCESS_ID, m_dyld_bid, break_addr);
341     }
342 
343     // Make sure our breakpoint is at the right address.
344     assert (target.GetBreakpointByID(m_dyld_bid)->FindLocationByAddress(break_addr)->GetBreakpoint().GetID() == m_dyld_bid);
345 }
346 
347 bool
348 DynamicLoaderPOSIXDYLD::RendezvousBreakpointHit(void *baton,
349                                                 StoppointCallbackContext *context,
350                                                 user_id_t break_id,
351                                                 user_id_t break_loc_id)
352 {
353     assert (baton && "null baton");
354     if (!baton)
355         return false;
356 
357     Log *log (GetLogIfAnyCategoriesSet(LIBLLDB_LOG_DYNAMIC_LOADER));
358     DynamicLoaderPOSIXDYLD *const dyld_instance = static_cast<DynamicLoaderPOSIXDYLD*>(baton);
359     if (log)
360         log->Printf ("DynamicLoaderPOSIXDYLD::%s called for pid %" PRIu64, __FUNCTION__, dyld_instance->m_process ? dyld_instance->m_process->GetID () : LLDB_INVALID_PROCESS_ID);
361 
362     dyld_instance->RefreshModules();
363 
364     // Return true to stop the target, false to just let the target run.
365     const bool stop_when_images_change = dyld_instance->GetStopWhenImagesChange();
366     if (log)
367         log->Printf ("DynamicLoaderPOSIXDYLD::%s pid %" PRIu64 " stop_when_images_change=%s", __FUNCTION__, dyld_instance->m_process ? dyld_instance->m_process->GetID () : LLDB_INVALID_PROCESS_ID, stop_when_images_change ? "true" : "false");
368     return stop_when_images_change;
369 }
370 
371 void
372 DynamicLoaderPOSIXDYLD::RefreshModules()
373 {
374     if (!m_rendezvous.Resolve())
375         return;
376 
377     DYLDRendezvous::iterator I;
378     DYLDRendezvous::iterator E;
379 
380     ModuleList &loaded_modules = m_process->GetTarget().GetImages();
381 
382     if (m_rendezvous.ModulesDidLoad())
383     {
384         ModuleList new_modules;
385 
386         E = m_rendezvous.loaded_end();
387         for (I = m_rendezvous.loaded_begin(); I != E; ++I)
388         {
389             FileSpec file(I->path.c_str(), true);
390             ModuleSP module_sp = LoadModuleAtAddress(file, I->link_addr, I->base_addr);
391             if (module_sp.get())
392             {
393                 loaded_modules.AppendIfNeeded(module_sp);
394                 new_modules.Append(module_sp);
395             }
396         }
397         m_process->GetTarget().ModulesDidLoad(new_modules);
398     }
399 
400     if (m_rendezvous.ModulesDidUnload())
401     {
402         ModuleList old_modules;
403 
404         E = m_rendezvous.unloaded_end();
405         for (I = m_rendezvous.unloaded_begin(); I != E; ++I)
406         {
407             FileSpec file(I->path.c_str(), true);
408             ModuleSpec module_spec (file);
409             ModuleSP module_sp =
410                 loaded_modules.FindFirstModule (module_spec);
411 
412             if (module_sp.get())
413             {
414                 old_modules.Append(module_sp);
415                 UnloadSections(module_sp);
416             }
417         }
418         loaded_modules.Remove(old_modules);
419         m_process->GetTarget().ModulesDidUnload(old_modules, false);
420     }
421 }
422 
423 ThreadPlanSP
424 DynamicLoaderPOSIXDYLD::GetStepThroughTrampolinePlan(Thread &thread, bool stop)
425 {
426     ThreadPlanSP thread_plan_sp;
427 
428     StackFrame *frame = thread.GetStackFrameAtIndex(0).get();
429     const SymbolContext &context = frame->GetSymbolContext(eSymbolContextSymbol);
430     Symbol *sym = context.symbol;
431 
432     if (sym == NULL || !sym->IsTrampoline())
433         return thread_plan_sp;
434 
435     const ConstString &sym_name = sym->GetMangled().GetName(Mangled::ePreferMangled);
436     if (!sym_name)
437         return thread_plan_sp;
438 
439     SymbolContextList target_symbols;
440     Target &target = thread.GetProcess()->GetTarget();
441     const ModuleList &images = target.GetImages();
442 
443     images.FindSymbolsWithNameAndType(sym_name, eSymbolTypeCode, target_symbols);
444     size_t num_targets = target_symbols.GetSize();
445     if (!num_targets)
446         return thread_plan_sp;
447 
448     typedef std::vector<lldb::addr_t> AddressVector;
449     AddressVector addrs;
450     for (size_t i = 0; i < num_targets; ++i)
451     {
452         SymbolContext context;
453         AddressRange range;
454         if (target_symbols.GetContextAtIndex(i, context))
455         {
456             context.GetAddressRange(eSymbolContextEverything, 0, false, range);
457             lldb::addr_t addr = range.GetBaseAddress().GetLoadAddress(&target);
458             if (addr != LLDB_INVALID_ADDRESS)
459                 addrs.push_back(addr);
460         }
461     }
462 
463     if (addrs.size() > 0)
464     {
465         AddressVector::iterator start = addrs.begin();
466         AddressVector::iterator end = addrs.end();
467 
468         std::sort(start, end);
469         addrs.erase(std::unique(start, end), end);
470         thread_plan_sp.reset(new ThreadPlanRunToAddress(thread, addrs, stop));
471     }
472 
473     return thread_plan_sp;
474 }
475 
476 void
477 DynamicLoaderPOSIXDYLD::LoadAllCurrentModules()
478 {
479     DYLDRendezvous::iterator I;
480     DYLDRendezvous::iterator E;
481     ModuleList module_list;
482 
483     if (!m_rendezvous.Resolve())
484     {
485         Log *log(GetLogIfAnyCategoriesSet(LIBLLDB_LOG_DYNAMIC_LOADER));
486         if (log)
487             log->Printf("DynamicLoaderPOSIXDYLD::%s unable to resolve POSIX DYLD rendezvous address",
488                         __FUNCTION__);
489         return;
490     }
491 
492     // The rendezvous class doesn't enumerate the main module, so track
493     // that ourselves here.
494     ModuleSP executable = GetTargetExecutable();
495     m_loaded_modules[executable] = m_rendezvous.GetLinkMapAddress();
496 
497 
498     for (I = m_rendezvous.begin(), E = m_rendezvous.end(); I != E; ++I)
499     {
500         const char *module_path = I->path.c_str();
501         FileSpec file(module_path, false);
502         ModuleSP module_sp = LoadModuleAtAddress(file, I->link_addr, I->base_addr);
503         if (module_sp.get())
504         {
505             module_list.Append(module_sp);
506         }
507         else
508         {
509             Log *log(GetLogIfAnyCategoriesSet(LIBLLDB_LOG_DYNAMIC_LOADER));
510             if (log)
511                 log->Printf("DynamicLoaderPOSIXDYLD::%s failed loading module %s at 0x%" PRIx64,
512                             __FUNCTION__, module_path, I->base_addr);
513         }
514     }
515 
516     m_process->GetTarget().ModulesDidLoad(module_list);
517 }
518 
519 addr_t
520 DynamicLoaderPOSIXDYLD::ComputeLoadOffset()
521 {
522     addr_t virt_entry;
523 
524     if (m_load_offset != LLDB_INVALID_ADDRESS)
525         return m_load_offset;
526 
527     if ((virt_entry = GetEntryPoint()) == LLDB_INVALID_ADDRESS)
528         return LLDB_INVALID_ADDRESS;
529 
530     ModuleSP module = m_process->GetTarget().GetExecutableModule();
531     if (!module)
532         return LLDB_INVALID_ADDRESS;
533 
534     ObjectFile *exe = module->GetObjectFile();
535     Address file_entry = exe->GetEntryPointAddress();
536 
537     if (!file_entry.IsValid())
538         return LLDB_INVALID_ADDRESS;
539 
540     m_load_offset = virt_entry - file_entry.GetFileAddress();
541     return m_load_offset;
542 }
543 
544 addr_t
545 DynamicLoaderPOSIXDYLD::GetEntryPoint()
546 {
547     if (m_entry_point != LLDB_INVALID_ADDRESS)
548         return m_entry_point;
549 
550     if (m_auxv.get() == NULL)
551         return LLDB_INVALID_ADDRESS;
552 
553     AuxVector::iterator I = m_auxv->FindEntry(AuxVector::AT_ENTRY);
554 
555     if (I == m_auxv->end())
556         return LLDB_INVALID_ADDRESS;
557 
558     m_entry_point = static_cast<addr_t>(I->value);
559     return m_entry_point;
560 }
561 
562 lldb::addr_t
563 DynamicLoaderPOSIXDYLD::GetThreadLocalData (const lldb::ModuleSP module, const lldb::ThreadSP thread)
564 {
565     auto it = m_loaded_modules.find (module);
566     if (it == m_loaded_modules.end())
567         return LLDB_INVALID_ADDRESS;
568 
569     addr_t link_map = it->second;
570     if (link_map == LLDB_INVALID_ADDRESS)
571         return LLDB_INVALID_ADDRESS;
572 
573     const DYLDRendezvous::ThreadInfo &metadata = m_rendezvous.GetThreadInfo();
574     if (!metadata.valid)
575         return LLDB_INVALID_ADDRESS;
576 
577     // Get the thread pointer.
578     addr_t tp = thread->GetThreadPointer ();
579     if (tp == LLDB_INVALID_ADDRESS)
580         return LLDB_INVALID_ADDRESS;
581 
582     // Find the module's modid.
583     int modid_size = 4;  // FIXME(spucci): This isn't right for big-endian 64-bit
584     int64_t modid = ReadUnsignedIntWithSizeInBytes (link_map + metadata.modid_offset, modid_size);
585     if (modid == -1)
586         return LLDB_INVALID_ADDRESS;
587 
588     // Lookup the DTV structure for this thread.
589     addr_t dtv_ptr = tp + metadata.dtv_offset;
590     addr_t dtv = ReadPointer (dtv_ptr);
591     if (dtv == LLDB_INVALID_ADDRESS)
592         return LLDB_INVALID_ADDRESS;
593 
594     // Find the TLS block for this module.
595     addr_t dtv_slot = dtv + metadata.dtv_slot_size*modid;
596     addr_t tls_block = ReadPointer (dtv_slot + metadata.tls_offset);
597 
598     Module *mod = module.get();
599     Log *log(GetLogIfAnyCategoriesSet(LIBLLDB_LOG_DYNAMIC_LOADER));
600     if (log)
601         log->Printf("DynamicLoaderPOSIXDYLD::Performed TLS lookup: "
602                     "module=%s, link_map=0x%" PRIx64 ", tp=0x%" PRIx64 ", modid=%" PRId64 ", tls_block=0x%" PRIx64 "\n",
603                     mod->GetObjectName().AsCString(""), link_map, tp, (int64_t)modid, tls_block);
604 
605     return tls_block;
606 }
607