1 //===-- DynamicLoaderPOSIXDYLD.cpp ----------------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 // Main header include
10 #include "DynamicLoaderPOSIXDYLD.h"
11 
12 #include "lldb/Breakpoint/BreakpointLocation.h"
13 #include "lldb/Core/Module.h"
14 #include "lldb/Core/ModuleSpec.h"
15 #include "lldb/Core/PluginManager.h"
16 #include "lldb/Core/Section.h"
17 #include "lldb/Symbol/Function.h"
18 #include "lldb/Symbol/ObjectFile.h"
19 #include "lldb/Target/MemoryRegionInfo.h"
20 #include "lldb/Target/Platform.h"
21 #include "lldb/Target/Target.h"
22 #include "lldb/Target/Thread.h"
23 #include "lldb/Target/ThreadPlanRunToAddress.h"
24 #include "lldb/Utility/Log.h"
25 #include "lldb/Utility/ProcessInfo.h"
26 
27 #include <memory>
28 
29 using namespace lldb;
30 using namespace lldb_private;
31 
32 LLDB_PLUGIN_DEFINE_ADV(DynamicLoaderPOSIXDYLD, DynamicLoaderPosixDYLD)
33 
34 void DynamicLoaderPOSIXDYLD::Initialize() {
35   PluginManager::RegisterPlugin(GetPluginNameStatic(),
36                                 GetPluginDescriptionStatic(), CreateInstance);
37 }
38 
39 void DynamicLoaderPOSIXDYLD::Terminate() {}
40 
41 lldb_private::ConstString DynamicLoaderPOSIXDYLD::GetPluginName() {
42   return GetPluginNameStatic();
43 }
44 
45 lldb_private::ConstString DynamicLoaderPOSIXDYLD::GetPluginNameStatic() {
46   static ConstString g_name("linux-dyld");
47   return g_name;
48 }
49 
50 const char *DynamicLoaderPOSIXDYLD::GetPluginDescriptionStatic() {
51   return "Dynamic loader plug-in that watches for shared library "
52          "loads/unloads in POSIX processes.";
53 }
54 
55 uint32_t DynamicLoaderPOSIXDYLD::GetPluginVersion() { return 1; }
56 
57 DynamicLoader *DynamicLoaderPOSIXDYLD::CreateInstance(Process *process,
58                                                       bool force) {
59   bool create = force;
60   if (!create) {
61     const llvm::Triple &triple_ref =
62         process->GetTarget().GetArchitecture().GetTriple();
63     if (triple_ref.getOS() == llvm::Triple::FreeBSD ||
64         triple_ref.getOS() == llvm::Triple::Linux ||
65         triple_ref.getOS() == llvm::Triple::NetBSD)
66       create = true;
67   }
68 
69   if (create)
70     return new DynamicLoaderPOSIXDYLD(process);
71   return nullptr;
72 }
73 
74 DynamicLoaderPOSIXDYLD::DynamicLoaderPOSIXDYLD(Process *process)
75     : DynamicLoader(process), m_rendezvous(process),
76       m_load_offset(LLDB_INVALID_ADDRESS), m_entry_point(LLDB_INVALID_ADDRESS),
77       m_auxv(), m_dyld_bid(LLDB_INVALID_BREAK_ID),
78       m_vdso_base(LLDB_INVALID_ADDRESS),
79       m_interpreter_base(LLDB_INVALID_ADDRESS), m_initial_modules_added(false) {
80 }
81 
82 DynamicLoaderPOSIXDYLD::~DynamicLoaderPOSIXDYLD() {
83   if (m_dyld_bid != LLDB_INVALID_BREAK_ID) {
84     m_process->GetTarget().RemoveBreakpointByID(m_dyld_bid);
85     m_dyld_bid = LLDB_INVALID_BREAK_ID;
86   }
87 }
88 
89 void DynamicLoaderPOSIXDYLD::DidAttach() {
90   Log *log(GetLogIfAnyCategoriesSet(LIBLLDB_LOG_DYNAMIC_LOADER));
91   LLDB_LOGF(log, "DynamicLoaderPOSIXDYLD::%s() pid %" PRIu64, __FUNCTION__,
92             m_process ? m_process->GetID() : LLDB_INVALID_PROCESS_ID);
93   m_auxv = std::make_unique<AuxVector>(m_process->GetAuxvData());
94 
95   LLDB_LOGF(
96       log, "DynamicLoaderPOSIXDYLD::%s pid %" PRIu64 " reloaded auxv data",
97       __FUNCTION__, m_process ? m_process->GetID() : LLDB_INVALID_PROCESS_ID);
98 
99   // ask the process if it can load any of its own modules
100   auto error = m_process->LoadModules();
101   LLDB_LOG_ERROR(log, std::move(error), "Couldn't load modules: {0}");
102 
103   ModuleSP executable_sp = GetTargetExecutable();
104   ResolveExecutableModule(executable_sp);
105   m_rendezvous.UpdateExecutablePath();
106 
107   // find the main process load offset
108   addr_t load_offset = ComputeLoadOffset();
109   LLDB_LOGF(log,
110             "DynamicLoaderPOSIXDYLD::%s pid %" PRIu64
111             " executable '%s', load_offset 0x%" PRIx64,
112             __FUNCTION__,
113             m_process ? m_process->GetID() : LLDB_INVALID_PROCESS_ID,
114             executable_sp ? executable_sp->GetFileSpec().GetPath().c_str()
115                           : "<null executable>",
116             load_offset);
117 
118   EvalSpecialModulesStatus();
119 
120   // if we dont have a load address we cant re-base
121   bool rebase_exec = load_offset != LLDB_INVALID_ADDRESS;
122 
123   // if we have a valid executable
124   if (executable_sp.get()) {
125     lldb_private::ObjectFile *obj = executable_sp->GetObjectFile();
126     if (obj) {
127       // don't rebase if the module already has a load address
128       Target &target = m_process->GetTarget();
129       Address addr = obj->GetImageInfoAddress(&target);
130       if (addr.GetLoadAddress(&target) != LLDB_INVALID_ADDRESS)
131         rebase_exec = false;
132     }
133   } else {
134     // no executable, nothing to re-base
135     rebase_exec = false;
136   }
137 
138   // if the target executable should be re-based
139   if (rebase_exec) {
140     ModuleList module_list;
141 
142     module_list.Append(executable_sp);
143     LLDB_LOGF(log,
144               "DynamicLoaderPOSIXDYLD::%s pid %" PRIu64
145               " added executable '%s' to module load list",
146               __FUNCTION__,
147               m_process ? m_process->GetID() : LLDB_INVALID_PROCESS_ID,
148               executable_sp->GetFileSpec().GetPath().c_str());
149 
150     UpdateLoadedSections(executable_sp, LLDB_INVALID_ADDRESS, load_offset,
151                          true);
152 
153     LoadAllCurrentModules();
154 
155     m_process->GetTarget().ModulesDidLoad(module_list);
156     if (log) {
157       LLDB_LOGF(log,
158                 "DynamicLoaderPOSIXDYLD::%s told the target about the "
159                 "modules that loaded:",
160                 __FUNCTION__);
161       for (auto module_sp : module_list.Modules()) {
162         LLDB_LOGF(log, "-- [module] %s (pid %" PRIu64 ")",
163                   module_sp ? module_sp->GetFileSpec().GetPath().c_str()
164                             : "<null>",
165                   m_process ? m_process->GetID() : LLDB_INVALID_PROCESS_ID);
166       }
167     }
168   }
169 
170   if (executable_sp.get()) {
171     if (!SetRendezvousBreakpoint()) {
172       // If we cannot establish rendezvous breakpoint right now we'll try again
173       // at entry point.
174       ProbeEntry();
175     }
176   }
177 }
178 
179 void DynamicLoaderPOSIXDYLD::DidLaunch() {
180   Log *log(GetLogIfAnyCategoriesSet(LIBLLDB_LOG_DYNAMIC_LOADER));
181   LLDB_LOGF(log, "DynamicLoaderPOSIXDYLD::%s()", __FUNCTION__);
182 
183   ModuleSP executable;
184   addr_t load_offset;
185 
186   m_auxv = std::make_unique<AuxVector>(m_process->GetAuxvData());
187 
188   executable = GetTargetExecutable();
189   load_offset = ComputeLoadOffset();
190   EvalSpecialModulesStatus();
191 
192   if (executable.get() && load_offset != LLDB_INVALID_ADDRESS) {
193     ModuleList module_list;
194     module_list.Append(executable);
195     UpdateLoadedSections(executable, LLDB_INVALID_ADDRESS, load_offset, true);
196 
197     LLDB_LOGF(log, "DynamicLoaderPOSIXDYLD::%s about to call ProbeEntry()",
198               __FUNCTION__);
199 
200     if (!SetRendezvousBreakpoint()) {
201       // If we cannot establish rendezvous breakpoint right now we'll try again
202       // at entry point.
203       ProbeEntry();
204     }
205 
206     LoadVDSO();
207     m_process->GetTarget().ModulesDidLoad(module_list);
208   }
209 }
210 
211 Status DynamicLoaderPOSIXDYLD::CanLoadImage() { return Status(); }
212 
213 void DynamicLoaderPOSIXDYLD::UpdateLoadedSections(ModuleSP module,
214                                                   addr_t link_map_addr,
215                                                   addr_t base_addr,
216                                                   bool base_addr_is_offset) {
217   m_loaded_modules[module] = link_map_addr;
218   UpdateLoadedSectionsCommon(module, base_addr, base_addr_is_offset);
219 }
220 
221 void DynamicLoaderPOSIXDYLD::UnloadSections(const ModuleSP module) {
222   m_loaded_modules.erase(module);
223 
224   UnloadSectionsCommon(module);
225 }
226 
227 void DynamicLoaderPOSIXDYLD::ProbeEntry() {
228   Log *log(GetLogIfAnyCategoriesSet(LIBLLDB_LOG_DYNAMIC_LOADER));
229 
230   const addr_t entry = GetEntryPoint();
231   if (entry == LLDB_INVALID_ADDRESS) {
232     LLDB_LOGF(
233         log,
234         "DynamicLoaderPOSIXDYLD::%s pid %" PRIu64
235         " GetEntryPoint() returned no address, not setting entry breakpoint",
236         __FUNCTION__, m_process ? m_process->GetID() : LLDB_INVALID_PROCESS_ID);
237     return;
238   }
239 
240   LLDB_LOGF(log,
241             "DynamicLoaderPOSIXDYLD::%s pid %" PRIu64
242             " GetEntryPoint() returned address 0x%" PRIx64
243             ", setting entry breakpoint",
244             __FUNCTION__,
245             m_process ? m_process->GetID() : LLDB_INVALID_PROCESS_ID, entry);
246 
247   if (m_process) {
248     Breakpoint *const entry_break =
249         m_process->GetTarget().CreateBreakpoint(entry, true, false).get();
250     entry_break->SetCallback(EntryBreakpointHit, this, true);
251     entry_break->SetBreakpointKind("shared-library-event");
252 
253     // Shoudn't hit this more than once.
254     entry_break->SetOneShot(true);
255   }
256 }
257 
258 // The runtime linker has run and initialized the rendezvous structure once the
259 // process has hit its entry point.  When we hit the corresponding breakpoint
260 // we interrogate the rendezvous structure to get the load addresses of all
261 // dependent modules for the process.  Similarly, we can discover the runtime
262 // linker function and setup a breakpoint to notify us of any dynamically
263 // loaded modules (via dlopen).
264 bool DynamicLoaderPOSIXDYLD::EntryBreakpointHit(
265     void *baton, StoppointCallbackContext *context, user_id_t break_id,
266     user_id_t break_loc_id) {
267   assert(baton && "null baton");
268   if (!baton)
269     return false;
270 
271   Log *log(GetLogIfAnyCategoriesSet(LIBLLDB_LOG_DYNAMIC_LOADER));
272   DynamicLoaderPOSIXDYLD *const dyld_instance =
273       static_cast<DynamicLoaderPOSIXDYLD *>(baton);
274   LLDB_LOGF(log, "DynamicLoaderPOSIXDYLD::%s called for pid %" PRIu64,
275             __FUNCTION__,
276             dyld_instance->m_process ? dyld_instance->m_process->GetID()
277                                      : LLDB_INVALID_PROCESS_ID);
278 
279   // Disable the breakpoint --- if a stop happens right after this, which we've
280   // seen on occasion, we don't want the breakpoint stepping thread-plan logic
281   // to show a breakpoint instruction at the disassembled entry point to the
282   // program.  Disabling it prevents it.  (One-shot is not enough - one-shot
283   // removal logic only happens after the breakpoint goes public, which wasn't
284   // happening in our scenario).
285   if (dyld_instance->m_process) {
286     BreakpointSP breakpoint_sp =
287         dyld_instance->m_process->GetTarget().GetBreakpointByID(break_id);
288     if (breakpoint_sp) {
289       LLDB_LOGF(log,
290                 "DynamicLoaderPOSIXDYLD::%s pid %" PRIu64
291                 " disabling breakpoint id %" PRIu64,
292                 __FUNCTION__, dyld_instance->m_process->GetID(), break_id);
293       breakpoint_sp->SetEnabled(false);
294     } else {
295       LLDB_LOGF(log,
296                 "DynamicLoaderPOSIXDYLD::%s pid %" PRIu64
297                 " failed to find breakpoint for breakpoint id %" PRIu64,
298                 __FUNCTION__, dyld_instance->m_process->GetID(), break_id);
299     }
300   } else {
301     LLDB_LOGF(log,
302               "DynamicLoaderPOSIXDYLD::%s breakpoint id %" PRIu64
303               " no Process instance!  Cannot disable breakpoint",
304               __FUNCTION__, break_id);
305   }
306 
307   dyld_instance->LoadAllCurrentModules();
308   dyld_instance->SetRendezvousBreakpoint();
309   return false; // Continue running.
310 }
311 
312 bool DynamicLoaderPOSIXDYLD::SetRendezvousBreakpoint() {
313   Log *log(GetLogIfAnyCategoriesSet(LIBLLDB_LOG_DYNAMIC_LOADER));
314   if (m_dyld_bid != LLDB_INVALID_BREAK_ID) {
315     LLDB_LOG(log,
316              "Rendezvous breakpoint breakpoint id {0} for pid {1}"
317              "is already set.",
318              m_dyld_bid,
319              m_process ? m_process->GetID() : LLDB_INVALID_PROCESS_ID);
320     return true;
321   }
322 
323   addr_t break_addr;
324   Target &target = m_process->GetTarget();
325   BreakpointSP dyld_break;
326   if (m_rendezvous.IsValid()) {
327     break_addr = m_rendezvous.GetBreakAddress();
328     LLDB_LOG(log, "Setting rendezvous break address for pid {0} at {1:x}",
329              m_process ? m_process->GetID() : LLDB_INVALID_PROCESS_ID,
330              break_addr);
331     dyld_break = target.CreateBreakpoint(break_addr, true, false);
332   } else {
333     LLDB_LOG(log, "Rendezvous structure is not set up yet. "
334                   "Trying to locate rendezvous breakpoint in the interpreter "
335                   "by symbol name.");
336     // Function names from different dynamic loaders that are known to be
337     // used as rendezvous between the loader and debuggers.
338     static std::vector<std::string> DebugStateCandidates{
339         "_dl_debug_state", "rtld_db_dlactivity", "__dl_rtld_db_dlactivity",
340         "r_debug_state",   "_r_debug_state",     "_rtld_debug_state",
341     };
342 
343     ModuleSP interpreter = LoadInterpreterModule();
344     if (!interpreter) {
345       FileSpecList containingModules;
346       containingModules.Append(
347           m_process->GetTarget().GetExecutableModulePointer()->GetFileSpec());
348 
349       dyld_break = target.CreateBreakpoint(
350           &containingModules, /*containingSourceFiles=*/nullptr,
351           DebugStateCandidates, eFunctionNameTypeFull, eLanguageTypeC,
352           /*offset=*/0,
353           /*skip_prologue=*/eLazyBoolNo,
354           /*internal=*/true,
355           /*request_hardware=*/false);
356     } else {
357       FileSpecList containingModules;
358       containingModules.Append(interpreter->GetFileSpec());
359       dyld_break = target.CreateBreakpoint(
360           &containingModules, /*containingSourceFiles=*/nullptr,
361           DebugStateCandidates, eFunctionNameTypeFull, eLanguageTypeC,
362           /*offset=*/0,
363           /*skip_prologue=*/eLazyBoolNo,
364           /*internal=*/true,
365           /*request_hardware=*/false);
366     }
367   }
368 
369   if (dyld_break->GetNumResolvedLocations() != 1) {
370     LLDB_LOG(
371         log,
372         "Rendezvous breakpoint has abnormal number of"
373         " resolved locations ({0}) in pid {1}. It's supposed to be exactly 1.",
374         dyld_break->GetNumResolvedLocations(),
375         m_process ? m_process->GetID() : LLDB_INVALID_PROCESS_ID);
376 
377     target.RemoveBreakpointByID(dyld_break->GetID());
378     return false;
379   }
380 
381   BreakpointLocationSP location = dyld_break->GetLocationAtIndex(0);
382   LLDB_LOG(log,
383            "Successfully set rendezvous breakpoint at address {0:x} "
384            "for pid {1}",
385            location->GetLoadAddress(),
386            m_process ? m_process->GetID() : LLDB_INVALID_PROCESS_ID);
387 
388   dyld_break->SetCallback(RendezvousBreakpointHit, this, true);
389   dyld_break->SetBreakpointKind("shared-library-event");
390   m_dyld_bid = dyld_break->GetID();
391   return true;
392 }
393 
394 bool DynamicLoaderPOSIXDYLD::RendezvousBreakpointHit(
395     void *baton, StoppointCallbackContext *context, user_id_t break_id,
396     user_id_t break_loc_id) {
397   assert(baton && "null baton");
398   if (!baton)
399     return false;
400 
401   Log *log(GetLogIfAnyCategoriesSet(LIBLLDB_LOG_DYNAMIC_LOADER));
402   DynamicLoaderPOSIXDYLD *const dyld_instance =
403       static_cast<DynamicLoaderPOSIXDYLD *>(baton);
404   LLDB_LOGF(log, "DynamicLoaderPOSIXDYLD::%s called for pid %" PRIu64,
405             __FUNCTION__,
406             dyld_instance->m_process ? dyld_instance->m_process->GetID()
407                                      : LLDB_INVALID_PROCESS_ID);
408 
409   dyld_instance->RefreshModules();
410 
411   // Return true to stop the target, false to just let the target run.
412   const bool stop_when_images_change = dyld_instance->GetStopWhenImagesChange();
413   LLDB_LOGF(log,
414             "DynamicLoaderPOSIXDYLD::%s pid %" PRIu64
415             " stop_when_images_change=%s",
416             __FUNCTION__,
417             dyld_instance->m_process ? dyld_instance->m_process->GetID()
418                                      : LLDB_INVALID_PROCESS_ID,
419             stop_when_images_change ? "true" : "false");
420   return stop_when_images_change;
421 }
422 
423 void DynamicLoaderPOSIXDYLD::RefreshModules() {
424   if (!m_rendezvous.Resolve())
425     return;
426 
427   DYLDRendezvous::iterator I;
428   DYLDRendezvous::iterator E;
429 
430   ModuleList &loaded_modules = m_process->GetTarget().GetImages();
431 
432   if (m_rendezvous.ModulesDidLoad() || !m_initial_modules_added) {
433     ModuleList new_modules;
434 
435     // If this is the first time rendezvous breakpoint fires, we need
436     // to take care of adding all the initial modules reported by
437     // the loader.  This is necessary to list ld-linux.so on Linux,
438     // and all DT_NEEDED entries on *BSD.
439     if (m_initial_modules_added) {
440       I = m_rendezvous.loaded_begin();
441       E = m_rendezvous.loaded_end();
442     } else {
443       I = m_rendezvous.begin();
444       E = m_rendezvous.end();
445       m_initial_modules_added = true;
446     }
447     for (; I != E; ++I) {
448       ModuleSP module_sp =
449           LoadModuleAtAddress(I->file_spec, I->link_addr, I->base_addr, true);
450       if (module_sp.get()) {
451         if (module_sp->GetObjectFile()->GetBaseAddress().GetLoadAddress(
452                 &m_process->GetTarget()) == m_interpreter_base &&
453             module_sp != m_interpreter_module.lock()) {
454           // If this is a duplicate instance of ld.so, unload it.  We may end up
455           // with it if we load it via a different path than before (symlink
456           // vs real path).
457           // TODO: remove this once we either fix library matching or avoid
458           // loading the interpreter when setting the rendezvous breakpoint.
459           UnloadSections(module_sp);
460           loaded_modules.Remove(module_sp);
461           continue;
462         }
463 
464         loaded_modules.AppendIfNeeded(module_sp);
465         new_modules.Append(module_sp);
466       }
467     }
468     m_process->GetTarget().ModulesDidLoad(new_modules);
469   }
470 
471   if (m_rendezvous.ModulesDidUnload()) {
472     ModuleList old_modules;
473 
474     E = m_rendezvous.unloaded_end();
475     for (I = m_rendezvous.unloaded_begin(); I != E; ++I) {
476       ModuleSpec module_spec{I->file_spec};
477       ModuleSP module_sp = loaded_modules.FindFirstModule(module_spec);
478 
479       if (module_sp.get()) {
480         old_modules.Append(module_sp);
481         UnloadSections(module_sp);
482       }
483     }
484     loaded_modules.Remove(old_modules);
485     m_process->GetTarget().ModulesDidUnload(old_modules, false);
486   }
487 }
488 
489 ThreadPlanSP
490 DynamicLoaderPOSIXDYLD::GetStepThroughTrampolinePlan(Thread &thread,
491                                                      bool stop) {
492   ThreadPlanSP thread_plan_sp;
493 
494   StackFrame *frame = thread.GetStackFrameAtIndex(0).get();
495   const SymbolContext &context = frame->GetSymbolContext(eSymbolContextSymbol);
496   Symbol *sym = context.symbol;
497 
498   if (sym == nullptr || !sym->IsTrampoline())
499     return thread_plan_sp;
500 
501   ConstString sym_name = sym->GetName();
502   if (!sym_name)
503     return thread_plan_sp;
504 
505   SymbolContextList target_symbols;
506   Target &target = thread.GetProcess()->GetTarget();
507   const ModuleList &images = target.GetImages();
508 
509   images.FindSymbolsWithNameAndType(sym_name, eSymbolTypeCode, target_symbols);
510   size_t num_targets = target_symbols.GetSize();
511   if (!num_targets)
512     return thread_plan_sp;
513 
514   typedef std::vector<lldb::addr_t> AddressVector;
515   AddressVector addrs;
516   for (size_t i = 0; i < num_targets; ++i) {
517     SymbolContext context;
518     AddressRange range;
519     if (target_symbols.GetContextAtIndex(i, context)) {
520       context.GetAddressRange(eSymbolContextEverything, 0, false, range);
521       lldb::addr_t addr = range.GetBaseAddress().GetLoadAddress(&target);
522       if (addr != LLDB_INVALID_ADDRESS)
523         addrs.push_back(addr);
524     }
525   }
526 
527   if (addrs.size() > 0) {
528     AddressVector::iterator start = addrs.begin();
529     AddressVector::iterator end = addrs.end();
530 
531     llvm::sort(start, end);
532     addrs.erase(std::unique(start, end), end);
533     thread_plan_sp =
534         std::make_shared<ThreadPlanRunToAddress>(thread, addrs, stop);
535   }
536 
537   return thread_plan_sp;
538 }
539 
540 void DynamicLoaderPOSIXDYLD::LoadVDSO() {
541   if (m_vdso_base == LLDB_INVALID_ADDRESS)
542     return;
543 
544   FileSpec file("[vdso]");
545 
546   MemoryRegionInfo info;
547   Status status = m_process->GetMemoryRegionInfo(m_vdso_base, info);
548   if (status.Fail()) {
549     Log *log(GetLogIfAnyCategoriesSet(LIBLLDB_LOG_DYNAMIC_LOADER));
550     LLDB_LOG(log, "Failed to get vdso region info: {0}", status);
551     return;
552   }
553 
554   if (ModuleSP module_sp = m_process->ReadModuleFromMemory(
555           file, m_vdso_base, info.GetRange().GetByteSize())) {
556     UpdateLoadedSections(module_sp, LLDB_INVALID_ADDRESS, m_vdso_base, false);
557     m_process->GetTarget().GetImages().AppendIfNeeded(module_sp);
558   }
559 }
560 
561 ModuleSP DynamicLoaderPOSIXDYLD::LoadInterpreterModule() {
562   if (m_interpreter_base == LLDB_INVALID_ADDRESS)
563     return nullptr;
564 
565   MemoryRegionInfo info;
566   Target &target = m_process->GetTarget();
567   Status status = m_process->GetMemoryRegionInfo(m_interpreter_base, info);
568   if (status.Fail() || info.GetMapped() != MemoryRegionInfo::eYes ||
569       info.GetName().IsEmpty()) {
570     Log *log(GetLogIfAnyCategoriesSet(LIBLLDB_LOG_DYNAMIC_LOADER));
571     LLDB_LOG(log, "Failed to get interpreter region info: {0}", status);
572     return nullptr;
573   }
574 
575   FileSpec file(info.GetName().GetCString());
576   ModuleSpec module_spec(file, target.GetArchitecture());
577 
578   if (ModuleSP module_sp = target.GetOrCreateModule(module_spec,
579                                                     true /* notify */)) {
580     UpdateLoadedSections(module_sp, LLDB_INVALID_ADDRESS, m_interpreter_base,
581                          false);
582     m_interpreter_module = module_sp;
583     return module_sp;
584   }
585   return nullptr;
586 }
587 
588 void DynamicLoaderPOSIXDYLD::LoadAllCurrentModules() {
589   DYLDRendezvous::iterator I;
590   DYLDRendezvous::iterator E;
591   ModuleList module_list;
592   Log *log(GetLogIfAnyCategoriesSet(LIBLLDB_LOG_DYNAMIC_LOADER));
593 
594   LoadVDSO();
595 
596   if (!m_rendezvous.Resolve()) {
597     LLDB_LOGF(log,
598               "DynamicLoaderPOSIXDYLD::%s unable to resolve POSIX DYLD "
599               "rendezvous address",
600               __FUNCTION__);
601     return;
602   }
603 
604   // The rendezvous class doesn't enumerate the main module, so track that
605   // ourselves here.
606   ModuleSP executable = GetTargetExecutable();
607   m_loaded_modules[executable] = m_rendezvous.GetLinkMapAddress();
608 
609   std::vector<FileSpec> module_names;
610   for (I = m_rendezvous.begin(), E = m_rendezvous.end(); I != E; ++I)
611     module_names.push_back(I->file_spec);
612   m_process->PrefetchModuleSpecs(
613       module_names, m_process->GetTarget().GetArchitecture().GetTriple());
614 
615   for (I = m_rendezvous.begin(), E = m_rendezvous.end(); I != E; ++I) {
616     ModuleSP module_sp =
617         LoadModuleAtAddress(I->file_spec, I->link_addr, I->base_addr, true);
618     if (module_sp.get()) {
619       LLDB_LOG(log, "LoadAllCurrentModules loading module: {0}",
620                I->file_spec.GetFilename());
621       module_list.Append(module_sp);
622     } else {
623       Log *log(GetLogIfAnyCategoriesSet(LIBLLDB_LOG_DYNAMIC_LOADER));
624       LLDB_LOGF(
625           log,
626           "DynamicLoaderPOSIXDYLD::%s failed loading module %s at 0x%" PRIx64,
627           __FUNCTION__, I->file_spec.GetCString(), I->base_addr);
628     }
629   }
630 
631   m_process->GetTarget().ModulesDidLoad(module_list);
632 }
633 
634 addr_t DynamicLoaderPOSIXDYLD::ComputeLoadOffset() {
635   addr_t virt_entry;
636 
637   if (m_load_offset != LLDB_INVALID_ADDRESS)
638     return m_load_offset;
639 
640   if ((virt_entry = GetEntryPoint()) == LLDB_INVALID_ADDRESS)
641     return LLDB_INVALID_ADDRESS;
642 
643   ModuleSP module = m_process->GetTarget().GetExecutableModule();
644   if (!module)
645     return LLDB_INVALID_ADDRESS;
646 
647   ObjectFile *exe = module->GetObjectFile();
648   if (!exe)
649     return LLDB_INVALID_ADDRESS;
650 
651   Address file_entry = exe->GetEntryPointAddress();
652 
653   if (!file_entry.IsValid())
654     return LLDB_INVALID_ADDRESS;
655 
656   m_load_offset = virt_entry - file_entry.GetFileAddress();
657   return m_load_offset;
658 }
659 
660 void DynamicLoaderPOSIXDYLD::EvalSpecialModulesStatus() {
661   if (llvm::Optional<uint64_t> vdso_base =
662           m_auxv->GetAuxValue(AuxVector::AUXV_AT_SYSINFO_EHDR))
663     m_vdso_base = *vdso_base;
664 
665   if (llvm::Optional<uint64_t> interpreter_base =
666           m_auxv->GetAuxValue(AuxVector::AUXV_AT_BASE))
667     m_interpreter_base = *interpreter_base;
668 }
669 
670 addr_t DynamicLoaderPOSIXDYLD::GetEntryPoint() {
671   if (m_entry_point != LLDB_INVALID_ADDRESS)
672     return m_entry_point;
673 
674   if (m_auxv == nullptr)
675     return LLDB_INVALID_ADDRESS;
676 
677   llvm::Optional<uint64_t> entry_point =
678       m_auxv->GetAuxValue(AuxVector::AUXV_AT_ENTRY);
679   if (!entry_point)
680     return LLDB_INVALID_ADDRESS;
681 
682   m_entry_point = static_cast<addr_t>(*entry_point);
683 
684   const ArchSpec &arch = m_process->GetTarget().GetArchitecture();
685 
686   // On ppc64, the entry point is actually a descriptor.  Dereference it.
687   if (arch.GetMachine() == llvm::Triple::ppc64)
688     m_entry_point = ReadUnsignedIntWithSizeInBytes(m_entry_point, 8);
689 
690   return m_entry_point;
691 }
692 
693 lldb::addr_t
694 DynamicLoaderPOSIXDYLD::GetThreadLocalData(const lldb::ModuleSP module_sp,
695                                            const lldb::ThreadSP thread,
696                                            lldb::addr_t tls_file_addr) {
697   auto it = m_loaded_modules.find(module_sp);
698   if (it == m_loaded_modules.end())
699     return LLDB_INVALID_ADDRESS;
700 
701   addr_t link_map = it->second;
702   if (link_map == LLDB_INVALID_ADDRESS)
703     return LLDB_INVALID_ADDRESS;
704 
705   const DYLDRendezvous::ThreadInfo &metadata = m_rendezvous.GetThreadInfo();
706   if (!metadata.valid)
707     return LLDB_INVALID_ADDRESS;
708 
709   // Get the thread pointer.
710   addr_t tp = thread->GetThreadPointer();
711   if (tp == LLDB_INVALID_ADDRESS)
712     return LLDB_INVALID_ADDRESS;
713 
714   // Find the module's modid.
715   int modid_size = 4; // FIXME(spucci): This isn't right for big-endian 64-bit
716   int64_t modid = ReadUnsignedIntWithSizeInBytes(
717       link_map + metadata.modid_offset, modid_size);
718   if (modid == -1)
719     return LLDB_INVALID_ADDRESS;
720 
721   // Lookup the DTV structure for this thread.
722   addr_t dtv_ptr = tp + metadata.dtv_offset;
723   addr_t dtv = ReadPointer(dtv_ptr);
724   if (dtv == LLDB_INVALID_ADDRESS)
725     return LLDB_INVALID_ADDRESS;
726 
727   // Find the TLS block for this module.
728   addr_t dtv_slot = dtv + metadata.dtv_slot_size * modid;
729   addr_t tls_block = ReadPointer(dtv_slot + metadata.tls_offset);
730 
731   Log *log(GetLogIfAnyCategoriesSet(LIBLLDB_LOG_DYNAMIC_LOADER));
732   LLDB_LOGF(log,
733             "DynamicLoaderPOSIXDYLD::Performed TLS lookup: "
734             "module=%s, link_map=0x%" PRIx64 ", tp=0x%" PRIx64
735             ", modid=%" PRId64 ", tls_block=0x%" PRIx64 "\n",
736             module_sp->GetObjectName().AsCString(""), link_map, tp,
737             (int64_t)modid, tls_block);
738 
739   if (tls_block == LLDB_INVALID_ADDRESS)
740     return LLDB_INVALID_ADDRESS;
741   else
742     return tls_block + tls_file_addr;
743 }
744 
745 void DynamicLoaderPOSIXDYLD::ResolveExecutableModule(
746     lldb::ModuleSP &module_sp) {
747   Log *log(GetLogIfAnyCategoriesSet(LIBLLDB_LOG_DYNAMIC_LOADER));
748 
749   if (m_process == nullptr)
750     return;
751 
752   auto &target = m_process->GetTarget();
753   const auto platform_sp = target.GetPlatform();
754 
755   ProcessInstanceInfo process_info;
756   if (!m_process->GetProcessInfo(process_info)) {
757     LLDB_LOGF(log,
758               "DynamicLoaderPOSIXDYLD::%s - failed to get process info for "
759               "pid %" PRIu64,
760               __FUNCTION__, m_process->GetID());
761     return;
762   }
763 
764   LLDB_LOGF(
765       log, "DynamicLoaderPOSIXDYLD::%s - got executable by pid %" PRIu64 ": %s",
766       __FUNCTION__, m_process->GetID(),
767       process_info.GetExecutableFile().GetPath().c_str());
768 
769   ModuleSpec module_spec(process_info.GetExecutableFile(),
770                          process_info.GetArchitecture());
771   if (module_sp && module_sp->MatchesModuleSpec(module_spec))
772     return;
773 
774   const auto executable_search_paths(Target::GetDefaultExecutableSearchPaths());
775   auto error = platform_sp->ResolveExecutable(
776       module_spec, module_sp,
777       !executable_search_paths.IsEmpty() ? &executable_search_paths : nullptr);
778   if (error.Fail()) {
779     StreamString stream;
780     module_spec.Dump(stream);
781 
782     LLDB_LOGF(log,
783               "DynamicLoaderPOSIXDYLD::%s - failed to resolve executable "
784               "with module spec \"%s\": %s",
785               __FUNCTION__, stream.GetData(), error.AsCString());
786     return;
787   }
788 
789   target.SetExecutableModule(module_sp, eLoadDependentsNo);
790 }
791 
792 bool DynamicLoaderPOSIXDYLD::AlwaysRelyOnEHUnwindInfo(
793     lldb_private::SymbolContext &sym_ctx) {
794   ModuleSP module_sp;
795   if (sym_ctx.symbol)
796     module_sp = sym_ctx.symbol->GetAddressRef().GetModule();
797   if (!module_sp && sym_ctx.function)
798     module_sp =
799         sym_ctx.function->GetAddressRange().GetBaseAddress().GetModule();
800   if (!module_sp)
801     return false;
802 
803   return module_sp->GetFileSpec().GetPath() == "[vdso]";
804 }
805