1 //===-- MemoryHistoryASan.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 "MemoryHistoryASan.h"
10 
11 #include "lldb/Target/MemoryHistory.h"
12 
13 #include "Plugins/Process/Utility/HistoryThread.h"
14 #include "lldb/Core/Debugger.h"
15 #include "lldb/Core/Module.h"
16 #include "lldb/Core/PluginInterface.h"
17 #include "lldb/Core/PluginManager.h"
18 #include "lldb/Core/ValueObject.h"
19 #include "lldb/Expression/UserExpression.h"
20 #include "lldb/Target/ExecutionContext.h"
21 #include "lldb/Target/Target.h"
22 #include "lldb/Target/Thread.h"
23 #include "lldb/Target/ThreadList.h"
24 #include "lldb/lldb-private.h"
25 
26 #include <sstream>
27 
28 using namespace lldb;
29 using namespace lldb_private;
30 
31 LLDB_PLUGIN_DEFINE(MemoryHistoryASan)
32 
33 MemoryHistorySP MemoryHistoryASan::CreateInstance(const ProcessSP &process_sp) {
34   if (!process_sp.get())
35     return nullptr;
36 
37   Target &target = process_sp->GetTarget();
38 
39   for (ModuleSP module_sp : target.GetImages().Modules()) {
40     const Symbol *symbol = module_sp->FindFirstSymbolWithNameAndType(
41         ConstString("__asan_get_alloc_stack"), lldb::eSymbolTypeAny);
42 
43     if (symbol != nullptr)
44       return MemoryHistorySP(new MemoryHistoryASan(process_sp));
45   }
46 
47   return MemoryHistorySP();
48 }
49 
50 void MemoryHistoryASan::Initialize() {
51   PluginManager::RegisterPlugin(
52       GetPluginNameStatic(), "ASan memory history provider.", CreateInstance);
53 }
54 
55 void MemoryHistoryASan::Terminate() {
56   PluginManager::UnregisterPlugin(CreateInstance);
57 }
58 
59 MemoryHistoryASan::MemoryHistoryASan(const ProcessSP &process_sp) {
60   if (process_sp)
61     m_process_wp = process_sp;
62 }
63 
64 const char *memory_history_asan_command_prefix = R"(
65     extern "C"
66     {
67         size_t __asan_get_alloc_stack(void *addr, void **trace, size_t size, int *thread_id);
68         size_t __asan_get_free_stack(void *addr, void **trace, size_t size, int *thread_id);
69     }
70 
71     struct data {
72         void *alloc_trace[256];
73         size_t alloc_count;
74         int alloc_tid;
75 
76         void *free_trace[256];
77         size_t free_count;
78         int free_tid;
79     };
80 )";
81 
82 const char *memory_history_asan_command_format =
83     R"(
84     data t;
85 
86     t.alloc_count = __asan_get_alloc_stack((void *)0x%)" PRIx64
87     R"(, t.alloc_trace, 256, &t.alloc_tid);
88     t.free_count = __asan_get_free_stack((void *)0x%)" PRIx64
89     R"(, t.free_trace, 256, &t.free_tid);
90 
91     t;
92 )";
93 
94 static void CreateHistoryThreadFromValueObject(ProcessSP process_sp,
95                                                ValueObjectSP return_value_sp,
96                                                const char *type,
97                                                const char *thread_name,
98                                                HistoryThreads &result) {
99   std::string count_path = "." + std::string(type) + "_count";
100   std::string tid_path = "." + std::string(type) + "_tid";
101   std::string trace_path = "." + std::string(type) + "_trace";
102 
103   ValueObjectSP count_sp =
104       return_value_sp->GetValueForExpressionPath(count_path.c_str());
105   ValueObjectSP tid_sp =
106       return_value_sp->GetValueForExpressionPath(tid_path.c_str());
107 
108   if (!count_sp || !tid_sp)
109     return;
110 
111   int count = count_sp->GetValueAsUnsigned(0);
112   tid_t tid = tid_sp->GetValueAsUnsigned(0) + 1;
113 
114   if (count <= 0)
115     return;
116 
117   ValueObjectSP trace_sp =
118       return_value_sp->GetValueForExpressionPath(trace_path.c_str());
119 
120   if (!trace_sp)
121     return;
122 
123   std::vector<lldb::addr_t> pcs;
124   for (int i = 0; i < count; i++) {
125     addr_t pc = trace_sp->GetChildAtIndex(i, true)->GetValueAsUnsigned(0);
126     if (pc == 0 || pc == 1 || pc == LLDB_INVALID_ADDRESS)
127       continue;
128     pcs.push_back(pc);
129   }
130 
131   // The ASAN runtime already massages the return addresses into call
132   // addresses, we don't want LLDB's unwinder to try to locate the previous
133   // instruction again as this might lead to us reporting a different line.
134   bool pcs_are_call_addresses = true;
135   HistoryThread *history_thread =
136       new HistoryThread(*process_sp, tid, pcs, pcs_are_call_addresses);
137   ThreadSP new_thread_sp(history_thread);
138   std::ostringstream thread_name_with_number;
139   thread_name_with_number << thread_name << " Thread " << tid;
140   history_thread->SetThreadName(thread_name_with_number.str().c_str());
141   // Save this in the Process' ExtendedThreadList so a strong pointer retains
142   // the object
143   process_sp->GetExtendedThreadList().AddThread(new_thread_sp);
144   result.push_back(new_thread_sp);
145 }
146 
147 HistoryThreads MemoryHistoryASan::GetHistoryThreads(lldb::addr_t address) {
148   HistoryThreads result;
149 
150   ProcessSP process_sp = m_process_wp.lock();
151   if (!process_sp)
152     return result;
153 
154   ThreadSP thread_sp =
155       process_sp->GetThreadList().GetExpressionExecutionThread();
156   if (!thread_sp)
157     return result;
158 
159   StackFrameSP frame_sp = thread_sp->GetSelectedFrame();
160   if (!frame_sp)
161     return result;
162 
163   ExecutionContext exe_ctx(frame_sp);
164   ValueObjectSP return_value_sp;
165   StreamString expr;
166   Status eval_error;
167   expr.Printf(memory_history_asan_command_format, address, address);
168 
169   EvaluateExpressionOptions options;
170   options.SetUnwindOnError(true);
171   options.SetTryAllThreads(true);
172   options.SetStopOthers(true);
173   options.SetIgnoreBreakpoints(true);
174   options.SetTimeout(process_sp->GetUtilityExpressionTimeout());
175   options.SetPrefix(memory_history_asan_command_prefix);
176   options.SetAutoApplyFixIts(false);
177   options.SetLanguage(eLanguageTypeObjC_plus_plus);
178 
179   ExpressionResults expr_result = UserExpression::Evaluate(
180       exe_ctx, options, expr.GetString(), "", return_value_sp, eval_error);
181   if (expr_result != eExpressionCompleted) {
182     StreamString ss;
183     ss << "cannot evaluate AddressSanitizer expression:\n";
184     ss << eval_error.AsCString();
185     Debugger::ReportWarning(ss.GetString().str(),
186                             process_sp->GetTarget().GetDebugger().GetID());
187     return result;
188   }
189 
190   if (!return_value_sp)
191     return result;
192 
193   CreateHistoryThreadFromValueObject(process_sp, return_value_sp, "free",
194                                      "Memory deallocated by", result);
195   CreateHistoryThreadFromValueObject(process_sp, return_value_sp, "alloc",
196                                      "Memory allocated by", result);
197 
198   return result;
199 }
200