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 "dalvik_system_VMStack.h"
18
19#include "art_method-inl.h"
20#include "jni_internal.h"
21#include "nth_caller_visitor.h"
22#include "mirror/class-inl.h"
23#include "mirror/class_loader.h"
24#include "mirror/object-inl.h"
25#include "scoped_fast_native_object_access.h"
26#include "scoped_thread_state_change.h"
27#include "thread_list.h"
28
29namespace art {
30
31static jobject GetThreadStack(const ScopedFastNativeObjectAccess& soa, jobject peer)
32    SHARED_REQUIRES(Locks::mutator_lock_) {
33  jobject trace = nullptr;
34  if (soa.Decode<mirror::Object*>(peer) == soa.Self()->GetPeer()) {
35    trace = soa.Self()->CreateInternalStackTrace<false>(soa);
36  } else {
37    // Suspend thread to build stack trace.
38    ScopedThreadSuspension sts(soa.Self(), kNative);
39    ThreadList* thread_list = Runtime::Current()->GetThreadList();
40    bool timed_out;
41    Thread* thread = thread_list->SuspendThreadByPeer(peer, true, false, &timed_out);
42    if (thread != nullptr) {
43      // Must be runnable to create returned array.
44      {
45        ScopedObjectAccess soa2(soa.Self());
46        trace = thread->CreateInternalStackTrace<false>(soa);
47      }
48      // Restart suspended thread.
49      thread_list->Resume(thread, false);
50    } else if (timed_out) {
51      LOG(ERROR) << "Trying to get thread's stack failed as the thread failed to suspend within a "
52          "generous timeout.";
53    }
54  }
55  return trace;
56}
57
58static jint VMStack_fillStackTraceElements(JNIEnv* env, jclass, jobject javaThread,
59                                           jobjectArray javaSteArray) {
60  ScopedFastNativeObjectAccess soa(env);
61  jobject trace = GetThreadStack(soa, javaThread);
62  if (trace == nullptr) {
63    return 0;
64  }
65  int32_t depth;
66  Thread::InternalStackTraceToStackTraceElementArray(soa, trace, javaSteArray, &depth);
67  return depth;
68}
69
70// Returns the defining class loader of the caller's caller.
71static jobject VMStack_getCallingClassLoader(JNIEnv* env, jclass) {
72  ScopedFastNativeObjectAccess soa(env);
73  NthCallerVisitor visitor(soa.Self(), 2);
74  visitor.WalkStack();
75  if (UNLIKELY(visitor.caller == nullptr)) {
76    // The caller is an attached native thread.
77    return nullptr;
78  }
79  return soa.AddLocalReference<jobject>(visitor.caller->GetDeclaringClass()->GetClassLoader());
80}
81
82static jobject VMStack_getClosestUserClassLoader(JNIEnv* env, jclass) {
83  struct ClosestUserClassLoaderVisitor : public StackVisitor {
84    explicit ClosestUserClassLoaderVisitor(Thread* thread)
85      : StackVisitor(thread, nullptr, StackVisitor::StackWalkKind::kIncludeInlinedFrames),
86        class_loader(nullptr) {}
87
88    bool VisitFrame() SHARED_REQUIRES(Locks::mutator_lock_) {
89      DCHECK(class_loader == nullptr);
90      mirror::Class* c = GetMethod()->GetDeclaringClass();
91      // c is null for runtime methods.
92      if (c != nullptr) {
93        mirror::Object* cl = c->GetClassLoader();
94        if (cl != nullptr) {
95          class_loader = cl;
96          return false;
97        }
98      }
99      return true;
100    }
101
102    mirror::Object* class_loader;
103  };
104  ScopedFastNativeObjectAccess soa(env);
105  ClosestUserClassLoaderVisitor visitor(soa.Self());
106  visitor.WalkStack();
107  return soa.AddLocalReference<jobject>(visitor.class_loader);
108}
109
110// Returns the class of the caller's caller's caller.
111static jclass VMStack_getStackClass2(JNIEnv* env, jclass) {
112  ScopedFastNativeObjectAccess soa(env);
113  NthCallerVisitor visitor(soa.Self(), 3);
114  visitor.WalkStack();
115  if (UNLIKELY(visitor.caller == nullptr)) {
116    // The caller is an attached native thread.
117    return nullptr;
118  }
119  return soa.AddLocalReference<jclass>(visitor.caller->GetDeclaringClass());
120}
121
122static jobjectArray VMStack_getThreadStackTrace(JNIEnv* env, jclass, jobject javaThread) {
123  ScopedFastNativeObjectAccess soa(env);
124  jobject trace = GetThreadStack(soa, javaThread);
125  if (trace == nullptr) {
126    return nullptr;
127  }
128  return Thread::InternalStackTraceToStackTraceElementArray(soa, trace);
129}
130
131static JNINativeMethod gMethods[] = {
132  NATIVE_METHOD(VMStack, fillStackTraceElements, "!(Ljava/lang/Thread;[Ljava/lang/StackTraceElement;)I"),
133  NATIVE_METHOD(VMStack, getCallingClassLoader, "!()Ljava/lang/ClassLoader;"),
134  NATIVE_METHOD(VMStack, getClosestUserClassLoader, "!()Ljava/lang/ClassLoader;"),
135  NATIVE_METHOD(VMStack, getStackClass2, "!()Ljava/lang/Class;"),
136  NATIVE_METHOD(VMStack, getThreadStackTrace, "!(Ljava/lang/Thread;)[Ljava/lang/StackTraceElement;"),
137};
138
139void register_dalvik_system_VMStack(JNIEnv* env) {
140  REGISTER_NATIVE_METHODS("dalvik/system/VMStack");
141}
142
143}  // namespace art
144