1 /*
2 * Copyright (C) 2008 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 "signal_catcher.h"
18
19 #include <csignal>
20 #include <cstdlib>
21 #include <fcntl.h>
22 #include <pthread.h>
23 #include <sys/stat.h>
24 #include <sys/time.h>
25 #include <sys/types.h>
26 #include <unistd.h>
27
28 #include <sstream>
29
30 #include <android-base/stringprintf.h>
31
32 #include "arch/instruction_set.h"
33 #include "base/logging.h" // For GetCmdLine.
34 #include "base/os.h"
35 #include "base/time_utils.h"
36 #include "base/utils.h"
37 #include "class_linker.h"
38 #include "gc/heap.h"
39 #include "jit/profile_saver.h"
40 #include "palette/palette.h"
41 #include "runtime.h"
42 #include "scoped_thread_state_change-inl.h"
43 #include "signal_set.h"
44 #include "thread.h"
45 #include "thread_list.h"
46
47 namespace art {
48
DumpCmdLine(std::ostream & os)49 static void DumpCmdLine(std::ostream& os) {
50 #if defined(__linux__)
51 // Show the original command line, and the current command line too if it's changed.
52 // On Android, /proc/self/cmdline will have been rewritten to something like "system_server".
53 // Note: The string "Cmd line:" is chosen to match the format used by debuggerd.
54 std::string current_cmd_line;
55 if (ReadFileToString("/proc/self/cmdline", ¤t_cmd_line)) {
56 current_cmd_line.resize(current_cmd_line.find_last_not_of('\0') + 1); // trim trailing '\0's
57 std::replace(current_cmd_line.begin(), current_cmd_line.end(), '\0', ' ');
58
59 os << "Cmd line: " << current_cmd_line << "\n";
60 const char* stashed_cmd_line = GetCmdLine();
61 if (stashed_cmd_line != nullptr && current_cmd_line != stashed_cmd_line
62 && strcmp(stashed_cmd_line, "<unset>") != 0) {
63 os << "Original command line: " << stashed_cmd_line << "\n";
64 }
65 }
66 #else
67 os << "Cmd line: " << GetCmdLine() << "\n";
68 #endif
69 }
70
SignalCatcher()71 SignalCatcher::SignalCatcher()
72 : lock_("SignalCatcher lock"),
73 cond_("SignalCatcher::cond_", lock_),
74 thread_(nullptr) {
75 SetHaltFlag(false);
76
77 // Create a raw pthread; its start routine will attach to the runtime.
78 CHECK_PTHREAD_CALL(pthread_create, (&pthread_, nullptr, &Run, this), "signal catcher thread");
79
80 Thread* self = Thread::Current();
81 MutexLock mu(self, lock_);
82 while (thread_ == nullptr) {
83 cond_.Wait(self);
84 }
85 }
86
~SignalCatcher()87 SignalCatcher::~SignalCatcher() {
88 // Since we know the thread is just sitting around waiting for signals
89 // to arrive, send it one.
90 SetHaltFlag(true);
91 CHECK_PTHREAD_CALL(pthread_kill, (pthread_, SIGQUIT), "signal catcher shutdown");
92 CHECK_PTHREAD_CALL(pthread_join, (pthread_, nullptr), "signal catcher shutdown");
93 }
94
SetHaltFlag(bool new_value)95 void SignalCatcher::SetHaltFlag(bool new_value) {
96 MutexLock mu(Thread::Current(), lock_);
97 halt_ = new_value;
98 }
99
ShouldHalt()100 bool SignalCatcher::ShouldHalt() {
101 MutexLock mu(Thread::Current(), lock_);
102 return halt_;
103 }
104
Output(const std::string & s)105 void SignalCatcher::Output(const std::string& s) {
106 ScopedThreadStateChange tsc(Thread::Current(), kWaitingForSignalCatcherOutput);
107 PaletteStatus status = PaletteWriteCrashThreadStacks(s.data(), s.size());
108 if (status == PaletteStatus::kOkay) {
109 LOG(INFO) << "Wrote stack traces to tombstoned";
110 } else {
111 CHECK(status == PaletteStatus::kFailedCheckLog);
112 LOG(ERROR) << "Failed to write stack traces to tombstoned";
113 }
114 }
115
HandleSigQuit()116 void SignalCatcher::HandleSigQuit() {
117 Runtime* runtime = Runtime::Current();
118 std::ostringstream os;
119 os << "\n"
120 << "----- pid " << getpid() << " at " << GetIsoDate() << " -----\n";
121
122 DumpCmdLine(os);
123
124 // Note: The strings "Build fingerprint:" and "ABI:" are chosen to match the format used by
125 // debuggerd. This allows, for example, the stack tool to work.
126 std::string fingerprint = runtime->GetFingerprint();
127 os << "Build fingerprint: '" << (fingerprint.empty() ? "unknown" : fingerprint) << "'\n";
128 os << "ABI: '" << GetInstructionSetString(runtime->GetInstructionSet()) << "'\n";
129
130 os << "Build type: " << (kIsDebugBuild ? "debug" : "optimized") << "\n";
131
132 runtime->DumpForSigQuit(os);
133
134 if ((false)) {
135 std::string maps;
136 if (ReadFileToString("/proc/self/maps", &maps)) {
137 os << "/proc/self/maps:\n" << maps;
138 }
139 }
140 os << "----- end " << getpid() << " -----\n";
141 Output(os.str());
142 }
143
HandleSigUsr1()144 void SignalCatcher::HandleSigUsr1() {
145 LOG(INFO) << "SIGUSR1 forcing GC (no HPROF) and profile save";
146 Runtime::Current()->GetHeap()->CollectGarbage(/* clear_soft_references= */ false);
147 ProfileSaver::ForceProcessProfiles();
148 }
149
WaitForSignal(Thread * self,SignalSet & signals)150 int SignalCatcher::WaitForSignal(Thread* self, SignalSet& signals) {
151 ScopedThreadStateChange tsc(self, kWaitingInMainSignalCatcherLoop);
152
153 // Signals for sigwait() must be blocked but not ignored. We
154 // block signals like SIGQUIT for all threads, so the condition
155 // is met. When the signal hits, we wake up, without any signal
156 // handlers being invoked.
157 int signal_number = signals.Wait();
158 if (!ShouldHalt()) {
159 // Let the user know we got the signal, just in case the system's too screwed for us to
160 // actually do what they want us to do...
161 LOG(INFO) << *self << ": reacting to signal " << signal_number;
162
163 // If anyone's holding locks (which might prevent us from getting back into state Runnable), say so...
164 Runtime::Current()->DumpLockHolders(LOG_STREAM(INFO));
165 }
166
167 return signal_number;
168 }
169
Run(void * arg)170 void* SignalCatcher::Run(void* arg) {
171 SignalCatcher* signal_catcher = reinterpret_cast<SignalCatcher*>(arg);
172 CHECK(signal_catcher != nullptr);
173
174 Runtime* runtime = Runtime::Current();
175 CHECK(runtime->AttachCurrentThread("Signal Catcher", true, runtime->GetSystemThreadGroup(),
176 !runtime->IsAotCompiler()));
177
178 Thread* self = Thread::Current();
179 DCHECK_NE(self->GetState(), kRunnable);
180 {
181 MutexLock mu(self, signal_catcher->lock_);
182 signal_catcher->thread_ = self;
183 signal_catcher->cond_.Broadcast(self);
184 }
185
186 // Set up mask with signals we want to handle.
187 SignalSet signals;
188 signals.Add(SIGQUIT);
189 signals.Add(SIGUSR1);
190
191 while (true) {
192 int signal_number = signal_catcher->WaitForSignal(self, signals);
193 if (signal_catcher->ShouldHalt()) {
194 runtime->DetachCurrentThread();
195 return nullptr;
196 }
197
198 switch (signal_number) {
199 case SIGQUIT:
200 signal_catcher->HandleSigQuit();
201 break;
202 case SIGUSR1:
203 signal_catcher->HandleSigUsr1();
204 break;
205 default:
206 LOG(ERROR) << "Unexpected signal %d" << signal_number;
207 break;
208 }
209 }
210 }
211
212 } // namespace art
213