1 /*
2 * Copyright (C) 2021 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #include "perfetto/base/build_config.h"
18
19 #if PERFETTO_BUILDFLAG(PERFETTO_OS_WIN)
20
21 #include <Windows.h>
22
23 #include "perfetto/ext/base/thread_task_runner.h"
24 #include "perfetto/tracing/internal/tracing_tls.h"
25 #include "perfetto/tracing/platform.h"
26
27 // Thread Termination Callbacks.
28 // Windows doesn't support a per-thread destructor with its
29 // TLS primitives. So, we build it manually by inserting a
30 // function to be called on each thread's exit.
31 // This magic is from chromium's base/threading/thread_local_storage_win.cc
32 // which in turn is from http://www.codeproject.com/threads/tls.asp.
33
34 #ifdef _WIN64
35 #pragma comment(linker, "/INCLUDE:_tls_used")
36 #pragma comment(linker, "/INCLUDE:perfetto_thread_callback_base")
37 #else
38 #pragma comment(linker, "/INCLUDE:__tls_used")
39 #pragma comment(linker, "/INCLUDE:_perfetto_thread_callback_base")
40 #endif
41
42 namespace perfetto {
43
44 namespace {
45
46 class PlatformWindows : public Platform {
47 public:
48 static PlatformWindows* instance;
49 PlatformWindows();
50 ~PlatformWindows() override;
51
52 ThreadLocalObject* GetOrCreateThreadLocalObject() override;
53 std::unique_ptr<base::TaskRunner> CreateTaskRunner(
54 const CreateTaskRunnerArgs&) override;
55 std::string GetCurrentProcessName() override;
56 void OnThreadExit();
57
58 private:
59 DWORD tls_key_{};
60 };
61
62 using ThreadLocalObject = Platform::ThreadLocalObject;
63
64 // static
65 PlatformWindows* PlatformWindows::instance = nullptr;
66
PlatformWindows()67 PlatformWindows::PlatformWindows() {
68 instance = this;
69 tls_key_ = ::TlsAlloc();
70 PERFETTO_CHECK(tls_key_ != TLS_OUT_OF_INDEXES);
71 }
72
~PlatformWindows()73 PlatformWindows::~PlatformWindows() {
74 ::TlsFree(tls_key_);
75 instance = nullptr;
76 }
77
OnThreadExit()78 void PlatformWindows::OnThreadExit() {
79 auto tls = static_cast<ThreadLocalObject*>(::TlsGetValue(tls_key_));
80 if (tls) {
81 // At this point we rely on the TLS object to be still set to the TracingTLS
82 // we are deleting. See comments in TracingTLS::~TracingTLS().
83 delete tls;
84 }
85 }
86
GetOrCreateThreadLocalObject()87 ThreadLocalObject* PlatformWindows::GetOrCreateThreadLocalObject() {
88 void* tls_ptr = ::TlsGetValue(tls_key_);
89
90 auto* tls = static_cast<ThreadLocalObject*>(tls_ptr);
91 if (!tls) {
92 tls = ThreadLocalObject::CreateInstance().release();
93 ::TlsSetValue(tls_key_, tls);
94 }
95 return tls;
96 }
97
CreateTaskRunner(const CreateTaskRunnerArgs & args)98 std::unique_ptr<base::TaskRunner> PlatformWindows::CreateTaskRunner(
99 const CreateTaskRunnerArgs& args) {
100 return std::unique_ptr<base::TaskRunner>(new base::ThreadTaskRunner(
101 base::ThreadTaskRunner::CreateAndStart(args.name_for_debugging)));
102 }
103
GetCurrentProcessName()104 std::string PlatformWindows::GetCurrentProcessName() {
105 char buf[MAX_PATH];
106 auto len = ::GetModuleFileNameA(nullptr /*current*/, buf, sizeof(buf));
107 std::string name(buf, static_cast<size_t>(len));
108 size_t sep = name.find_last_of('\\');
109 if (sep != std::string::npos)
110 name = name.substr(sep + 1);
111 return name;
112 }
113
114 } // namespace
115
116 // static
GetDefaultPlatform()117 Platform* Platform::GetDefaultPlatform() {
118 static PlatformWindows* thread_safe_init_instance = new PlatformWindows();
119 return thread_safe_init_instance;
120 }
121
122 } // namespace perfetto
123
124 // -----------------------
125 // Thread-local destructor
126 // -----------------------
127
128 // .CRT$XLA to .CRT$XLZ is an array of PIMAGE_TLS_CALLBACK pointers that are
129 // called automatically by the OS loader code (not the CRT) when the module is
130 // loaded and on thread creation. They are NOT called if the module has been
131 // loaded by a LoadLibrary() call. It must have implicitly been loaded at
132 // process startup.
133 // See VC\crt\src\tlssup.c for reference.
134
135 // extern "C" suppresses C++ name mangling so we know the symbol name for the
136 // linker /INCLUDE:symbol pragma above.
137 extern "C" {
138 // The linker must not discard perfetto_thread_callback_base. (We force a
139 // reference to this variable with a linker /INCLUDE:symbol pragma to ensure
140 // that.) If this variable is discarded, the OnThreadExit function will never be
141 // called.
142
143 void NTAPI PerfettoOnThreadExit(PVOID, DWORD, PVOID);
PerfettoOnThreadExit(PVOID,DWORD reason,PVOID)144 void NTAPI PerfettoOnThreadExit(PVOID, DWORD reason, PVOID) {
145 if (reason == DLL_THREAD_DETACH || reason == DLL_PROCESS_DETACH) {
146 if (perfetto::PlatformWindows::instance)
147 perfetto::PlatformWindows::instance->OnThreadExit();
148 }
149 }
150
151 #ifdef _WIN64
152
153 // .CRT section is merged with .rdata on x64 so it must be constant data.
154 #pragma const_seg(".CRT$XLP")
155
156 // When defining a const variable, it must have external linkage to be sure the
157 // linker doesn't discard it.
158 extern const PIMAGE_TLS_CALLBACK perfetto_thread_callback_base;
159 const PIMAGE_TLS_CALLBACK perfetto_thread_callback_base = PerfettoOnThreadExit;
160
161 // Reset the default section.
162 #pragma const_seg()
163
164 #else // _WIN64
165
166 #pragma data_seg(".CRT$XLP")
167 PIMAGE_TLS_CALLBACK perfetto_thread_callback_base = PerfettoOnThreadExit;
168 // Reset the default section.
169 #pragma data_seg()
170
171 #endif // _WIN64
172
173 } // extern "C"
174
175 #endif // OS_WIN
176