1 /* Copyright (C) 2017 The Android Open Source Project 2 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 3 * 4 * This file implements interfaces from the file jvmti.h. This implementation 5 * is licensed under the same terms as the file jvmti.h. The 6 * copyright and license information for the file jvmti.h follows. 7 * 8 * Copyright (c) 2003, 2011, Oracle and/or its affiliates. All rights reserved. 9 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 10 * 11 * This code is free software; you can redistribute it and/or modify it 12 * under the terms of the GNU General Public License version 2 only, as 13 * published by the Free Software Foundation. Oracle designates this 14 * particular file as subject to the "Classpath" exception as provided 15 * by Oracle in the LICENSE file that accompanied this code. 16 * 17 * This code is distributed in the hope that it will be useful, but WITHOUT 18 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 19 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 20 * version 2 for more details (a copy is included in the LICENSE file that 21 * accompanied this code). 22 * 23 * You should have received a copy of the GNU General Public License version 24 * 2 along with this work; if not, write to the Free Software Foundation, 25 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 26 * 27 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 28 * or visit www.oracle.com if you need additional information or have any 29 * questions. 30 */ 31 32 #ifndef ART_OPENJDKJVMTI_TI_THREAD_H_ 33 #define ART_OPENJDKJVMTI_TI_THREAD_H_ 34 35 #include <unordered_map> 36 37 #include "jni.h" 38 #include "jvmti.h" 39 40 #include "base/macros.h" 41 #include "base/mutex.h" 42 #include "handle.h" 43 #include "thread.h" 44 45 namespace art { 46 class ArtField; 47 class ScopedObjectAccessAlreadyRunnable; 48 class Thread; 49 class Closure; 50 namespace mirror { 51 class Throwable; 52 } // namespace mirror 53 } // namespace art 54 55 namespace openjdkjvmti { 56 57 class EventHandler; 58 59 // Gains the user_code_suspension_lock_ and ensures that the code will not suspend for user-code. 60 class SCOPED_CAPABILITY ScopedNoUserCodeSuspension { 61 public: 62 explicit ScopedNoUserCodeSuspension(art::Thread* self) 63 ACQUIRE(art::Locks::user_code_suspension_lock_); 64 ~ScopedNoUserCodeSuspension() RELEASE(art::Locks::user_code_suspension_lock_); 65 66 private: 67 art::Thread* self_; 68 }; 69 70 // The struct that we store in the art::Thread::custom_tls_ that maps the jvmtiEnvs to the data 71 // stored with that thread. This is needed since different jvmtiEnvs are not supposed to share TLS 72 // data but we only have a single slot in Thread objects to store data. 73 struct JvmtiGlobalTLSData : public art::TLSData { 74 std::unordered_map<jvmtiEnv*, const void*> data GUARDED_BY(art::Locks::thread_list_lock_); 75 76 // The depth of the last frame where popping using PopFrame it is not allowed. It is set to 77 // kNoDisallowedPopFrame if all frames can be popped. See b/117615146 for more information. 78 static constexpr size_t kNoDisallowedPopFrame = -1; 79 size_t disable_pop_frame_depth = kNoDisallowedPopFrame; 80 }; 81 82 class ThreadUtil { 83 public: 84 static void Register(EventHandler* event_handler); 85 static void Unregister(); 86 87 // To be called when it is safe to cache data. This means that we have at least entered the 88 // RuntimePhase::kInit but we might or might not have already called VMInit event. 89 static void CacheData(); 90 91 // Called just after we have sent the VMInit callback so that ThreadUtil can do final setup. This 92 // ensures that there are no timing issues between the two callbacks. 93 static void VMInitEventSent() REQUIRES_SHARED(art::Locks::mutator_lock_); 94 95 // Handle a jvmtiEnv going away. 96 static void RemoveEnvironment(jvmtiEnv* env); 97 98 static jvmtiError GetAllThreads(jvmtiEnv* env, jint* threads_count_ptr, jthread** threads_ptr); 99 100 static jvmtiError GetCurrentThread(jvmtiEnv* env, jthread* thread_ptr); 101 102 static jvmtiError GetThreadInfo(jvmtiEnv* env, jthread thread, jvmtiThreadInfo* info_ptr); 103 104 static jvmtiError GetThreadState(jvmtiEnv* env, jthread thread, jint* thread_state_ptr); 105 106 static jvmtiError SetThreadLocalStorage(jvmtiEnv* env, jthread thread, const void* data); 107 static jvmtiError GetThreadLocalStorage(jvmtiEnv* env, jthread thread, void** data_ptr); 108 109 static jvmtiError RunAgentThread(jvmtiEnv* env, 110 jthread thread, 111 jvmtiStartFunction proc, 112 const void* arg, 113 jint priority); 114 115 static jvmtiError SuspendThread(jvmtiEnv* env, jthread thread); 116 static jvmtiError ResumeThread(jvmtiEnv* env, jthread thread); 117 118 static jvmtiError SuspendThreadList(jvmtiEnv* env, 119 jint request_count, 120 const jthread* threads, 121 jvmtiError* results); 122 static jvmtiError ResumeThreadList(jvmtiEnv* env, 123 jint request_count, 124 const jthread* threads, 125 jvmtiError* results); 126 127 static jvmtiError StopThread(jvmtiEnv* env, jthread thr, jobject exception); 128 static jvmtiError InterruptThread(jvmtiEnv* env, jthread thr); 129 130 // Returns true if we decoded the thread and it is alive, false otherwise with an appropriate 131 // error placed into 'err'. A thread is alive if it has had it's 'start' function called and has 132 // (or at least could have) executed managed code and has not yet returned past it's first managed 133 // frame. This means that the thread returned might have IsStillStarting() return true. Code that 134 // does not consider that alive should check manually. 135 static bool GetAliveNativeThread(jthread thread, 136 const art::ScopedObjectAccessAlreadyRunnable& soa, 137 /*out*/ art::Thread** thr, 138 /*out*/ jvmtiError* err) 139 REQUIRES_SHARED(art::Locks::mutator_lock_) 140 REQUIRES(art::Locks::thread_list_lock_); 141 142 // Returns true if we decoded the thread, false otherwise with an appropriate error placed into 143 // 'err' 144 static bool GetNativeThread(jthread thread, 145 const art::ScopedObjectAccessAlreadyRunnable& soa, 146 /*out*/ art::Thread** thr, 147 /*out*/ jvmtiError* err) 148 REQUIRES_SHARED(art::Locks::mutator_lock_) 149 REQUIRES(art::Locks::thread_list_lock_); 150 151 // Go to sleep if this thread is suspended. 152 static void SuspendCheck(art::Thread* self) 153 REQUIRES(!art::Locks::mutator_lock_, !art::Locks::user_code_suspension_lock_); 154 155 // Returns true if the thread would be suspended if it locks the mutator-lock or calls 156 // SuspendCheck. This function is called with the user_code_suspension_lock already held. 157 static bool WouldSuspendForUserCodeLocked(art::Thread* self) 158 REQUIRES(art::Locks::user_code_suspension_lock_, 159 !art::Locks::thread_suspend_count_lock_); 160 161 // Returns true if this thread would go to sleep if it locks the mutator-lock or calls 162 // SuspendCheck. 163 static bool WouldSuspendForUserCode(art::Thread* self) 164 REQUIRES(!art::Locks::user_code_suspension_lock_, 165 !art::Locks::thread_suspend_count_lock_); 166 167 static JvmtiGlobalTLSData* GetGlobalTLSData(art::Thread* thread) 168 REQUIRES(art::Locks::thread_list_lock_); 169 static JvmtiGlobalTLSData* GetOrCreateGlobalTLSData(art::Thread* thread) 170 REQUIRES(art::Locks::thread_list_lock_); 171 172 private: 173 // We need to make sure only one thread tries to suspend threads at a time so we can get the 174 // 'suspend-only-once' behavior the spec requires. Internally, ART considers suspension to be a 175 // counted state, allowing a single thread to be suspended multiple times by different users. This 176 // makes mapping into the JVMTI idea of thread suspension difficult. We have decided to split the 177 // difference and ensure that JVMTI tries to treat suspension as the boolean flag as much as 178 // possible with the suspend/resume methods but only do best effort. On the other hand 179 // GetThreadState will be totally accurate as much as possible. This means that calling 180 // ResumeThread on a thread that has state JVMTI_THREAD_STATE_SUSPENDED will not necessarily 181 // cause the thread to wake up if the thread is suspended for the debugger or gc or something. 182 static jvmtiError SuspendSelf(art::Thread* self) 183 REQUIRES(!art::Locks::mutator_lock_, !art::Locks::user_code_suspension_lock_); 184 static jvmtiError SuspendOther(art::Thread* self, jthread target_jthread) 185 REQUIRES(!art::Locks::mutator_lock_, !art::Locks::user_code_suspension_lock_); 186 187 static art::ArtField* context_class_loader_; 188 }; 189 190 } // namespace openjdkjvmti 191 192 #endif // ART_OPENJDKJVMTI_TI_THREAD_H_ 193