1 /*
2 * Copyright (C) 2016 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 <type_traits>
18
19 extern "C" {
20
21 #include "qurt.h"
22
23 } // extern "C"
24
25 #include "chre/core/event_loop.h"
26 #include "chre/core/event_loop_manager.h"
27 #include "chre/core/init.h"
28 #include "chre/core/nanoapp.h"
29 #include "chre/platform/log.h"
30 #include "chre/platform/memory.h"
31 #include "chre/platform/mutex.h"
32 #include "chre/platform/platform_nanoapp.h"
33 #include "chre/platform/slpi/fastrpc.h"
34 #include "chre/platform/static_nanoapps.h"
35 #include "chre/util/lock_guard.h"
36
37 using chre::EventLoop;
38 using chre::LockGuard;
39 using chre::Mutex;
40
41 extern "C" int chre_slpi_stop_thread(void);
42
43 namespace {
44
45 //! Size of the stack for the CHRE thread, in bytes.
46 constexpr size_t kStackSize = (8 * 1024);
47
48 //! Memory partition where the thread control block (TCB) should be stored,
49 //! which controls micro-image support (0 = big image, 1 = micro image).
50 //! @see qurt_thread_attr_set_tcb_partition
51 constexpr unsigned char kTcbPartition = 0;
52
53 //! How long we wait (in microseconds) between checks on whether the CHRE thread
54 //! has exited after we invoked stop().
55 constexpr qurt_timer_duration_t kThreadStatusPollingIntervalUsec = 5000; // 5ms
56
57 //! Pointer to the main CHRE event loop. Modification must only be done while
58 //! the CHRE thread is stopped, and while holding gThreadMutex.
59 EventLoop *gEventLoop;
60
61 //! Buffer to use for the CHRE thread's stack.
62 typename std::aligned_storage<kStackSize>::type gStack;
63
64 //! QuRT OS handle for the CHRE thread.
65 qurt_thread_t gThreadHandle;
66
67 //! Protects access to thread metadata, like gThreadRunning, during critical
68 //! sections (starting/stopping the CHRE thread).
69 Mutex *gThreadMutex;
70 typename std::aligned_storage<sizeof(Mutex), alignof(Mutex)>::type
71 gThreadMutexStorage;
72
73 //! Set to true when the CHRE thread starts, and false when it exits normally.
74 bool gThreadRunning;
75
76 //! A thread-local storage key, which is currently only used to add a thread
77 //! destructor callback for the host FastRPC thread.
78 int gTlsKey;
79 bool gTlsKeyValid;
80
81 // TODO: We would prefer to just use staitc global C++ constructor/destructor
82 // support, but currently, destructors do not seem to get called. These work as
83 // a temporary workaround, though.
84 __attribute__((constructor))
onLoad(void)85 void onLoad(void) {
86 gThreadMutex = new(&gThreadMutexStorage) Mutex();
87 }
88
89 __attribute__((destructor))
onUnload(void)90 void onUnload(void) {
91 gThreadMutex->~Mutex();
92 gThreadMutex = nullptr;
93 }
94
95 /**
96 * Entry point for the QuRT thread that runs CHRE.
97 *
98 * @param data Argument passed to qurt_thread_create()
99 */
chreThreadEntry(void *)100 void chreThreadEntry(void * /*data*/) {
101 chre::init();
102 gEventLoop = chre::EventLoopManagerSingleton::get()->createEventLoop();
103 if (gEventLoop == nullptr) {
104 LOGE("Failed to create event loop!");
105 } else {
106 loadStaticNanoapps(gEventLoop);
107 gEventLoop->run();
108 }
109
110 chre::deinit();
111 gEventLoop = nullptr;
112 gThreadRunning = false;
113 LOGD("CHRE thread exiting");
114 }
115
onHostProcessTerminated(void *)116 void onHostProcessTerminated(void * /*data*/) {
117 LOGW("Host process died, exiting CHRE (running %d)", gThreadRunning);
118 chre_slpi_stop_thread();
119 }
120
121 } // anonymous namespace
122
123 namespace chre {
124
getCurrentEventLoop()125 EventLoop *getCurrentEventLoop() {
126 return (qurt_thread_get_id() == gThreadHandle) ? gEventLoop : nullptr;
127 }
128
129 } // namespace chre
130
131 /**
132 * Invoked over FastRPC to initialize and start the CHRE thread.
133 *
134 * @return 0 on success, nonzero on failure (per FastRPC requirements)
135 */
chre_slpi_start_thread(void)136 extern "C" int chre_slpi_start_thread(void) {
137 // This lock ensures that we only start the thread once
138 LockGuard<Mutex> lock(*gThreadMutex);
139 int fastRpcResult = CHRE_FASTRPC_ERROR;
140
141 if (gThreadRunning) {
142 LOGE("CHRE thread already running");
143 } else {
144 // Human-readable name for the CHRE thread (not const in QuRT API, but they
145 // make a copy)
146 char threadName[] = "CHRE";
147 qurt_thread_attr_t attributes;
148
149 qurt_thread_attr_init(&attributes);
150 qurt_thread_attr_set_stack_addr(&attributes, &gStack);
151 qurt_thread_attr_set_stack_size(&attributes, kStackSize);
152 qurt_thread_attr_set_name(&attributes, threadName);
153 qurt_thread_attr_set_tcb_partition(&attributes, kTcbPartition);
154
155 int result = qurt_thread_create(&gThreadHandle, &attributes,
156 chreThreadEntry, nullptr);
157 if (result != QURT_EOK) {
158 LOGE("Couldn't create CHRE thread: %d", result);
159 } else {
160 LOGD("Started CHRE thread");
161 gThreadRunning = true;
162 fastRpcResult = CHRE_FASTRPC_SUCCESS;
163 }
164 }
165
166 return fastRpcResult;
167 }
168
169 /**
170 * Blocks until the CHRE thread exits. Called over FastRPC to monitor for
171 * abnormal termination of the CHRE thread and/or SLPI as a whole.
172 *
173 * @return Always returns 0, indicating success (per FastRPC requirements)
174 */
chre_slpi_wait_on_thread_exit(void)175 extern "C" int chre_slpi_wait_on_thread_exit(void) {
176 if (!gThreadRunning) {
177 LOGE("Tried monitoring for CHRE thread exit, but thread not running!");
178 } else {
179 int status;
180 int result = qurt_thread_join(gThreadHandle, &status);
181 if (result != QURT_EOK) {
182 LOGE("qurt_thread_join failed with result %d", result);
183 }
184 LOGI("Detected CHRE thread exit");
185 }
186
187 return CHRE_FASTRPC_SUCCESS;
188 }
189
190 /**
191 * If the CHRE thread is running, requests it to perform graceful shutdown,
192 * waits for it to exit, then completes teardown.
193 *
194 * @return Always returns 0, indicating success (per FastRPC requirements)
195 */
chre_slpi_stop_thread(void)196 extern "C" int chre_slpi_stop_thread(void) {
197 // This lock ensures that we will complete shutdown before the thread can be
198 // started again
199 LockGuard<Mutex> lock(*gThreadMutex);
200
201 if (!gThreadRunning || gEventLoop == nullptr) {
202 LOGD("Tried to stop CHRE thread, but not running");
203 } else {
204 gEventLoop->stop();
205
206 // Poll until the thread has stopped; note that we can't use
207 // qurt_thread_join() here because chreMonitorThread() will already be
208 // blocking in it, and attempting to join the same target from two threads
209 // is invalid. Technically, we could use a condition variable, but this is
210 // simpler and we don't care too much about being notified right away.
211 while (gThreadRunning) {
212 qurt_timer_sleep(kThreadStatusPollingIntervalUsec);
213 }
214 gThreadHandle = 0;
215
216 // TODO: need to figure out the right place to put this, to make sure we're
217 // not trying to post events to an EventLoop that is already stopped, etc.
218 // Becomes even trickier when log messages get routed through the HostLink.
219 chre::HostLinkBase::shutdown();
220
221 if (gTlsKeyValid) {
222 int ret = qurt_tls_delete_key(gTlsKey);
223 if (ret != QURT_EOK) {
224 // Note: LOGE is not necessarily safe to use after stopping CHRE
225 FARF(ERROR, "Deleting TLS key failed: %d", ret);
226 }
227 gTlsKeyValid = false;
228 }
229 }
230
231 return CHRE_FASTRPC_SUCCESS;
232 }
233
234 /**
235 * Creates a thread-local storage (TLS) key in QuRT, which we use to inject a
236 * destructor that is called when the current FastRPC thread terminates. This is
237 * used to get a notification when the original FastRPC thread dies for any
238 * reason, so we can stop the CHRE thread.
239 *
240 * Note that this needs to be invoked from a separate thread on the host process
241 * side. It doesn't work if called from a thread that will be blocking inside a
242 * FastRPC call, such as the monitor thread.
243 *
244 * @return 0 on success, nonzero on failure (per FastRPC requirements)
245 */
chre_slpi_initialize_reverse_monitor(void)246 extern "C" int chre_slpi_initialize_reverse_monitor(void) {
247 LockGuard<Mutex> lock(*gThreadMutex);
248
249 if (!gTlsKeyValid) {
250 int result = qurt_tls_create_key(&gTlsKey, onHostProcessTerminated);
251 if (result != QURT_EOK) {
252 LOGE("Couldn't create TLS key: %d", result);
253 } else {
254 // We need to set the value to something for the destructor to be invoked
255 result = qurt_tls_set_specific(gTlsKey, &gTlsKey);
256 if (result != QURT_EOK) {
257 LOGE("Couldn't set TLS data: %d", result);
258 qurt_tls_delete_key(gTlsKey);
259 } else {
260 gTlsKeyValid = true;
261 }
262 }
263 }
264
265 return (gTlsKeyValid) ? CHRE_FASTRPC_SUCCESS : CHRE_FASTRPC_ERROR;
266 }
267
268 // TODO: Remove this stub once the symbol is provided.
__cxa_finalize(void *)269 extern "C" void __cxa_finalize(void *) {}
270