1 //===-- InstrumentationRuntimeMainThreadChecker.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 #include "InstrumentationRuntimeMainThreadChecker.h"
10 
11 #include "Plugins/Process/Utility/HistoryThread.h"
12 #include "lldb/Breakpoint/StoppointCallbackContext.h"
13 #include "lldb/Core/Module.h"
14 #include "lldb/Core/PluginManager.h"
15 #include "lldb/Symbol/Symbol.h"
16 #include "lldb/Symbol/SymbolContext.h"
17 #include "lldb/Symbol/Variable.h"
18 #include "lldb/Symbol/VariableList.h"
19 #include "lldb/Target/InstrumentationRuntimeStopInfo.h"
20 #include "lldb/Target/RegisterContext.h"
21 #include "lldb/Target/SectionLoadList.h"
22 #include "lldb/Target/StopInfo.h"
23 #include "lldb/Target/Target.h"
24 #include "lldb/Target/Thread.h"
25 #include "lldb/Utility/RegularExpression.h"
26 
27 #include <memory>
28 
29 using namespace lldb;
30 using namespace lldb_private;
31 
32 LLDB_PLUGIN_DEFINE(InstrumentationRuntimeMainThreadChecker)
33 
34 InstrumentationRuntimeMainThreadChecker::
35     ~InstrumentationRuntimeMainThreadChecker() {
36   Deactivate();
37 }
38 
39 lldb::InstrumentationRuntimeSP
40 InstrumentationRuntimeMainThreadChecker::CreateInstance(
41     const lldb::ProcessSP &process_sp) {
42   return InstrumentationRuntimeSP(
43       new InstrumentationRuntimeMainThreadChecker(process_sp));
44 }
45 
46 void InstrumentationRuntimeMainThreadChecker::Initialize() {
47   PluginManager::RegisterPlugin(
48       GetPluginNameStatic(),
49       "MainThreadChecker instrumentation runtime plugin.", CreateInstance,
50       GetTypeStatic);
51 }
52 
53 void InstrumentationRuntimeMainThreadChecker::Terminate() {
54   PluginManager::UnregisterPlugin(CreateInstance);
55 }
56 
57 lldb::InstrumentationRuntimeType
58 InstrumentationRuntimeMainThreadChecker::GetTypeStatic() {
59   return eInstrumentationRuntimeTypeMainThreadChecker;
60 }
61 
62 const RegularExpression &
63 InstrumentationRuntimeMainThreadChecker::GetPatternForRuntimeLibrary() {
64   static RegularExpression regex(llvm::StringRef("libMainThreadChecker.dylib"));
65   return regex;
66 }
67 
68 bool InstrumentationRuntimeMainThreadChecker::CheckIfRuntimeIsValid(
69     const lldb::ModuleSP module_sp) {
70   static ConstString test_sym("__main_thread_checker_on_report");
71   const Symbol *symbol =
72       module_sp->FindFirstSymbolWithNameAndType(test_sym, lldb::eSymbolTypeAny);
73   return symbol != nullptr;
74 }
75 
76 StructuredData::ObjectSP
77 InstrumentationRuntimeMainThreadChecker::RetrieveReportData(
78     ExecutionContextRef exe_ctx_ref) {
79   ProcessSP process_sp = GetProcessSP();
80   if (!process_sp)
81     return StructuredData::ObjectSP();
82 
83   ThreadSP thread_sp = exe_ctx_ref.GetThreadSP();
84   StackFrameSP frame_sp = thread_sp->GetSelectedFrame();
85   ModuleSP runtime_module_sp = GetRuntimeModuleSP();
86   Target &target = process_sp->GetTarget();
87 
88   if (!frame_sp)
89     return StructuredData::ObjectSP();
90 
91   RegisterContextSP regctx_sp = frame_sp->GetRegisterContext();
92   if (!regctx_sp)
93     return StructuredData::ObjectSP();
94 
95   const RegisterInfo *reginfo = regctx_sp->GetRegisterInfoByName("arg1");
96   if (!reginfo)
97     return StructuredData::ObjectSP();
98 
99   uint64_t apiname_ptr = regctx_sp->ReadRegisterAsUnsigned(reginfo, 0);
100   if (!apiname_ptr)
101     return StructuredData::ObjectSP();
102 
103   std::string apiName;
104   Status read_error;
105   target.ReadCStringFromMemory(apiname_ptr, apiName, read_error);
106   if (read_error.Fail())
107     return StructuredData::ObjectSP();
108 
109   std::string className;
110   std::string selector;
111   if (apiName.substr(0, 2) == "-[") {
112     size_t spacePos = apiName.find(' ');
113     if (spacePos != std::string::npos) {
114       className = apiName.substr(2, spacePos - 2);
115       selector = apiName.substr(spacePos + 1, apiName.length() - spacePos - 2);
116     }
117   }
118 
119   // Gather the PCs of the user frames in the backtrace.
120   StructuredData::Array *trace = new StructuredData::Array();
121   auto trace_sp = StructuredData::ObjectSP(trace);
122   StackFrameSP responsible_frame;
123   for (unsigned I = 0; I < thread_sp->GetStackFrameCount(); ++I) {
124     StackFrameSP frame = thread_sp->GetStackFrameAtIndex(I);
125     Address addr = frame->GetFrameCodeAddressForSymbolication();
126     if (addr.GetModule() == runtime_module_sp) // Skip PCs from the runtime.
127       continue;
128 
129     // The first non-runtime frame is responsible for the bug.
130     if (!responsible_frame)
131       responsible_frame = frame;
132 
133     lldb::addr_t PC = addr.GetLoadAddress(&target);
134     trace->AddItem(StructuredData::ObjectSP(new StructuredData::Integer(PC)));
135   }
136 
137   auto *d = new StructuredData::Dictionary();
138   auto dict_sp = StructuredData::ObjectSP(d);
139   d->AddStringItem("instrumentation_class", "MainThreadChecker");
140   d->AddStringItem("api_name", apiName);
141   d->AddStringItem("class_name", className);
142   d->AddStringItem("selector", selector);
143   d->AddStringItem("description",
144                    apiName + " must be used from main thread only");
145   d->AddIntegerItem("tid", thread_sp->GetIndexID());
146   d->AddItem("trace", trace_sp);
147   return dict_sp;
148 }
149 
150 bool InstrumentationRuntimeMainThreadChecker::NotifyBreakpointHit(
151     void *baton, StoppointCallbackContext *context, user_id_t break_id,
152     user_id_t break_loc_id) {
153   assert(baton && "null baton");
154   if (!baton)
155     return false; ///< false => resume execution.
156 
157   InstrumentationRuntimeMainThreadChecker *const instance =
158       static_cast<InstrumentationRuntimeMainThreadChecker *>(baton);
159 
160   ProcessSP process_sp = instance->GetProcessSP();
161   ThreadSP thread_sp = context->exe_ctx_ref.GetThreadSP();
162   if (!process_sp || !thread_sp ||
163       process_sp != context->exe_ctx_ref.GetProcessSP())
164     return false;
165 
166   if (process_sp->GetModIDRef().IsLastResumeForUserExpression())
167     return false;
168 
169   StructuredData::ObjectSP report =
170       instance->RetrieveReportData(context->exe_ctx_ref);
171 
172   if (report) {
173     std::string description = std::string(report->GetAsDictionary()
174                                               ->GetValueForKey("description")
175                                               ->GetAsString()
176                                               ->GetValue());
177     thread_sp->SetStopInfo(
178         InstrumentationRuntimeStopInfo::CreateStopReasonWithInstrumentationData(
179             *thread_sp, description, report));
180     return true;
181   }
182 
183   return false;
184 }
185 
186 void InstrumentationRuntimeMainThreadChecker::Activate() {
187   if (IsActive())
188     return;
189 
190   ProcessSP process_sp = GetProcessSP();
191   if (!process_sp)
192     return;
193 
194   ModuleSP runtime_module_sp = GetRuntimeModuleSP();
195 
196   ConstString symbol_name("__main_thread_checker_on_report");
197   const Symbol *symbol = runtime_module_sp->FindFirstSymbolWithNameAndType(
198       symbol_name, eSymbolTypeCode);
199 
200   if (symbol == nullptr)
201     return;
202 
203   if (!symbol->ValueIsAddress() || !symbol->GetAddressRef().IsValid())
204     return;
205 
206   Target &target = process_sp->GetTarget();
207   addr_t symbol_address = symbol->GetAddressRef().GetOpcodeLoadAddress(&target);
208 
209   if (symbol_address == LLDB_INVALID_ADDRESS)
210     return;
211 
212   Breakpoint *breakpoint =
213       process_sp->GetTarget()
214           .CreateBreakpoint(symbol_address, /*internal=*/true,
215                             /*hardware=*/false)
216           .get();
217   const bool sync = false;
218   breakpoint->SetCallback(
219       InstrumentationRuntimeMainThreadChecker::NotifyBreakpointHit, this, sync);
220   breakpoint->SetBreakpointKind("main-thread-checker-report");
221   SetBreakpointID(breakpoint->GetID());
222 
223   SetActive(true);
224 }
225 
226 void InstrumentationRuntimeMainThreadChecker::Deactivate() {
227   SetActive(false);
228 
229   auto BID = GetBreakpointID();
230   if (BID == LLDB_INVALID_BREAK_ID)
231     return;
232 
233   if (ProcessSP process_sp = GetProcessSP()) {
234     process_sp->GetTarget().RemoveBreakpointByID(BID);
235     SetBreakpointID(LLDB_INVALID_BREAK_ID);
236   }
237 }
238 
239 lldb::ThreadCollectionSP
240 InstrumentationRuntimeMainThreadChecker::GetBacktracesFromExtendedStopInfo(
241     StructuredData::ObjectSP info) {
242   ThreadCollectionSP threads;
243   threads = std::make_shared<ThreadCollection>();
244 
245   ProcessSP process_sp = GetProcessSP();
246 
247   if (info->GetObjectForDotSeparatedPath("instrumentation_class")
248           ->GetStringValue() != "MainThreadChecker")
249     return threads;
250 
251   std::vector<lldb::addr_t> PCs;
252   auto trace = info->GetObjectForDotSeparatedPath("trace")->GetAsArray();
253   trace->ForEach([&PCs](StructuredData::Object *PC) -> bool {
254     PCs.push_back(PC->GetAsInteger()->GetValue());
255     return true;
256   });
257 
258   if (PCs.empty())
259     return threads;
260 
261   StructuredData::ObjectSP thread_id_obj =
262       info->GetObjectForDotSeparatedPath("tid");
263   tid_t tid = thread_id_obj ? thread_id_obj->GetIntegerValue() : 0;
264 
265   // We gather symbolication addresses above, so no need for HistoryThread to
266   // try to infer the call addresses.
267   bool pcs_are_call_addresses = true;
268   ThreadSP new_thread_sp = std::make_shared<HistoryThread>(
269       *process_sp, tid, PCs, pcs_are_call_addresses);
270 
271   // Save this in the Process' ExtendedThreadList so a strong pointer retains
272   // the object
273   process_sp->GetExtendedThreadList().AddThread(new_thread_sp);
274   threads->AddThread(new_thread_sp);
275 
276   return threads;
277 }
278