rev 9061 : 8227011: Starting a JFR recording in response to JVMTI VMInit and / or Java agent premain corrupts memory
Reviewed-by: egahlin, rwestberg

   1 /*
   2  * Copyright (c) 2016, 2018, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "jni.h"
  27 #include "classfile/symbolTable.hpp"
  28 #include "classfile/systemDictionary.hpp"
  29 #include "classfile/vmSymbols.hpp"
  30 #include "jfr/jni/jfrJavaSupport.hpp"
  31 #include "jfr/recorder/storage/jfrStorage.hpp"
  32 #include "jfr/support/jfrThreadId.hpp"
  33 #include "jfr/utilities/jfrTypes.hpp"
  34 #include "jfr/writers/jfrJavaEventWriter.hpp"
  35 #include "oops/instanceKlass.hpp"
  36 #include "oops/oop.inline.hpp"
  37 #include "runtime/fieldDescriptor.hpp"
  38 #include "runtime/handles.hpp"
  39 #include "runtime/jniHandles.hpp"
  40 #include "runtime/thread.inline.hpp"
  41 
  42 static int start_pos_offset = invalid_offset;
  43 static int start_pos_address_offset = invalid_offset;
  44 static int current_pos_offset = invalid_offset;
  45 static int max_pos_offset = invalid_offset;
  46 static int max_event_size_offset = invalid_offset;
  47 static int notified_offset = invalid_offset;
  48 static int thread_id_offset = invalid_offset;
  49 static int valid_offset = invalid_offset;
  50 
  51 static bool find_field(InstanceKlass* ik,
  52                        Symbol* name_symbol,
  53                        Symbol* signature_symbol,
  54                        fieldDescriptor* fd,
  55                        bool is_static = false,
  56                        bool allow_super = false) {
  57   if (allow_super || is_static) {
  58     return ik->find_field(name_symbol, signature_symbol, is_static, fd) != NULL;
  59   } else {
  60     return ik->find_local_field(name_symbol, signature_symbol, fd);
  61   }
  62 }
  63 
  64 static void compute_offset(int &dest_offset,
  65                            Klass* klass,
  66                            Symbol* name_symbol,
  67                            Symbol* signature_symbol,
  68                            bool is_static = false, bool allow_super = false) {
  69   fieldDescriptor fd;
  70   InstanceKlass* ik = InstanceKlass::cast(klass);
  71   if (!find_field(ik, name_symbol, signature_symbol, &fd, is_static, allow_super)) {
  72     assert(false, "invariant");
  73   }
  74   dest_offset = fd.offset();
  75 }
  76 
  77 static bool setup_event_writer_offsets(TRAPS) {
  78   const char class_name[] = "jdk/jfr/internal/EventWriter";
  79   Symbol* const k_sym = SymbolTable::lookup(class_name, sizeof class_name - 1, CHECK_false);
  80   assert(k_sym != NULL, "invariant");
  81   Klass* klass = SystemDictionary::resolve_or_fail(k_sym, true, CHECK_false);
  82   assert(klass != NULL, "invariant");
  83 
  84   const char start_pos_name[] = "startPosition";
  85   Symbol* const start_pos_sym = SymbolTable::lookup(start_pos_name, sizeof start_pos_name - 1, CHECK_false);
  86   assert(start_pos_sym != NULL, "invariant");
  87   assert(invalid_offset == start_pos_offset, "invariant");
  88   compute_offset(start_pos_offset, klass, start_pos_sym, vmSymbols::long_signature());
  89   assert(start_pos_offset != invalid_offset, "invariant");
  90 
  91   const char start_pos_address_name[] = "startPositionAddress";
  92   Symbol* const start_pos_address_sym = SymbolTable::lookup(start_pos_address_name, sizeof start_pos_address_name - 1, CHECK_false);
  93   assert(start_pos_address_sym != NULL, "invariant");
  94   assert(invalid_offset == start_pos_address_offset, "invariant");
  95   compute_offset(start_pos_address_offset, klass, start_pos_address_sym, vmSymbols::long_signature());
  96   assert(start_pos_address_offset != invalid_offset, "invariant");
  97 
  98   const char event_pos_name[] = "currentPosition";
  99   Symbol* const event_pos_sym = SymbolTable::lookup(event_pos_name, sizeof event_pos_name - 1, CHECK_false);
 100   assert(event_pos_sym != NULL, "invariant");
 101   assert(invalid_offset == current_pos_offset, "invariant");
 102   compute_offset(current_pos_offset, klass, event_pos_sym,vmSymbols::long_signature());
 103   assert(current_pos_offset != invalid_offset, "invariant");
 104 
 105   const char max_pos_name[] = "maxPosition";
 106   Symbol* const max_pos_sym = SymbolTable::lookup(max_pos_name, sizeof max_pos_name - 1, CHECK_false);
 107   assert(max_pos_sym != NULL, "invariant");
 108   assert(invalid_offset == max_pos_offset, "invariant");
 109   compute_offset(max_pos_offset, klass, max_pos_sym, vmSymbols::long_signature());
 110   assert(max_pos_offset != invalid_offset, "invariant");
 111 
 112   const char max_event_size_name[] = "maxEventSize";
 113   Symbol* const max_event_size_sym = SymbolTable::lookup(max_event_size_name, sizeof max_event_size_name - 1, CHECK_false);
 114   assert (max_event_size_sym != NULL, "invariant");
 115   assert(invalid_offset == max_event_size_offset, "invariant");
 116   compute_offset(max_event_size_offset, klass, max_event_size_sym, vmSymbols::int_signature());
 117   assert(max_event_size_offset != invalid_offset, "invariant");
 118 
 119   const char notified_name[] = "notified";
 120   Symbol* const notified_sym = SymbolTable::lookup(notified_name, sizeof notified_name - 1, CHECK_false);
 121   assert (notified_sym != NULL, "invariant");
 122   assert(invalid_offset == notified_offset, "invariant");
 123   compute_offset(notified_offset, klass, notified_sym, vmSymbols::bool_signature());
 124   assert(notified_offset != invalid_offset, "invariant");
 125 
 126   const char valid_name[] = "valid";
 127   Symbol* const valid_sym = SymbolTable::lookup(valid_name, sizeof valid_name - 1, CHECK_false);
 128   assert (valid_sym != NULL, "invariant");
 129   assert(invalid_offset == valid_offset, "invariant");
 130   compute_offset(valid_offset, klass, valid_sym, vmSymbols::bool_signature());
 131   assert(valid_offset != invalid_offset, "invariant");
 132   return true;
 133 }
 134 
 135 bool JfrJavaEventWriter::has_required_classes(TRAPS) {
 136   const char class_name[] = "jdk/jfr/internal/EventWriter";
 137   Symbol* const k_sym = SymbolTable::lookup(class_name, sizeof class_name - 1, CHECK_false);
 138   Klass* klass = SystemDictionary::resolve_or_null(k_sym, CHECK_false);
 139   return (klass != NULL);
 140 }
 141 
 142 bool JfrJavaEventWriter::initialize() {
 143   static bool initialized = false;
 144   if (!initialized) {
 145     initialized = setup_event_writer_offsets(Thread::current());

 146   }
 147   return initialized;
 148 }
 149 
 150 jboolean JfrJavaEventWriter::flush(jobject writer, jint used, jint requested, JavaThread* jt) {
 151   DEBUG_ONLY(JfrJavaSupport::check_java_thread_in_vm(jt));
 152   assert(writer != NULL, "invariant");
 153   oop const w = JNIHandles::resolve_non_null(writer);
 154   assert(w != NULL, "invariant");
 155   JfrBuffer* const current = jt->jfr_thread_local()->java_buffer();
 156   assert(current != NULL, "invariant");
 157   JfrBuffer* const buffer = JfrStorage::flush(current, used, requested, false, jt);
 158   assert(buffer != NULL, "invariant");
 159   // "validity" is contextually defined here to mean
 160   // that some memory location was provided that is
 161   // large enough to accommodate the "requested size".
 162   const bool is_valid = buffer->free_size() >= (size_t)(used + requested);
 163   u1* const new_current_position = is_valid ? buffer->pos() + used : buffer->pos();
 164   assert(start_pos_offset != invalid_offset, "invariant");
 165   w->long_field_put(start_pos_offset, (jlong)buffer->pos());
 166   w->long_field_put(current_pos_offset, (jlong)new_current_position);
 167   // only update java writer if underlying memory changed
 168   if (buffer != current) {
 169     w->long_field_put(start_pos_address_offset, (jlong)buffer->pos_address());
 170     w->long_field_put(max_pos_offset, (jlong)buffer->end());
 171   }
 172   if (!is_valid) {
 173     // mark writer as invalid for this write attempt
 174     w->release_bool_field_put(valid_offset, JNI_FALSE);
 175     return JNI_FALSE;
 176   }
 177   // An exclusive use of a leased buffer is treated equivalent to
 178   // holding a system resource. As such, it should be released as soon as possible.
 179   // Returning true here signals that the thread will need to call flush again
 180   // on EventWriter.endEvent() and that flush will return the lease.
 181   return buffer->lease() ? JNI_TRUE : JNI_FALSE;
 182 }
 183 
 184 class JfrJavaEventWriterNotificationClosure : public ThreadClosure {
 185  public:
 186    void do_thread(Thread* t) {
 187      if (t->is_Java_thread()) {
 188        JfrJavaEventWriter::notify((JavaThread*)t);
 189      }
 190    }
 191 };
 192 
 193 void JfrJavaEventWriter::notify() {
 194   assert(SafepointSynchronize::is_at_safepoint(), "invariant");
 195   JfrJavaEventWriterNotificationClosure closure;
 196   Threads::threads_do(&closure);
 197 }
 198 
 199 void JfrJavaEventWriter::notify(JavaThread* jt) {
 200   assert(jt != NULL, "invariant");
 201   assert(SafepointSynchronize::is_at_safepoint(), "invariant");
 202   if (jt->jfr_thread_local()->has_java_event_writer()) {
 203     oop buffer_writer = JNIHandles::resolve_non_null(jt->jfr_thread_local()->java_event_writer());
 204     assert(buffer_writer != NULL, "invariant");
 205     buffer_writer->release_bool_field_put(notified_offset, JNI_TRUE);
 206   }
 207 }
 208 
 209 static jobject create_new_event_writer(JfrBuffer* buffer, TRAPS) {
 210   assert(buffer != NULL, "invariant");
 211   DEBUG_ONLY(JfrJavaSupport::check_java_thread_in_vm(THREAD));
 212   HandleMark hm(THREAD);
 213   static const char klass[] = "jdk/jfr/internal/EventWriter";
 214   static const char method[] = "<init>";
 215   static const char signature[] = "(JJJJZ)V";
 216   JavaValue result(T_OBJECT);
 217   JfrJavaArguments args(&result, klass, method, signature, CHECK_NULL);
 218   // parameters
 219   args.push_long((jlong)buffer->pos());
 220   args.push_long((jlong)buffer->end());
 221   args.push_long((jlong)buffer->pos_address());
 222   args.push_long((jlong)JFR_THREAD_ID(THREAD));
 223   args.push_int((int)JNI_TRUE);
 224   JfrJavaSupport::new_object_global_ref(&args, CHECK_NULL);
 225   return result.get_jobject();
 226 }
 227 
 228 jobject JfrJavaEventWriter::event_writer(Thread* t) {
 229   DEBUG_ONLY(JfrJavaSupport::check_java_thread_in_vm(t));
 230   JfrThreadLocal* const tl = t->jfr_thread_local();
 231   assert(tl->shelved_buffer() == NULL, "invariant");
 232   return tl->java_event_writer();
 233 }
 234 
 235 jobject JfrJavaEventWriter::new_event_writer(TRAPS) {
 236   DEBUG_ONLY(JfrJavaSupport::check_java_thread_in_vm(THREAD));
 237   assert(event_writer(THREAD) == NULL, "invariant");
 238   JfrThreadLocal* const tl = THREAD->jfr_thread_local();
 239   assert(!tl->has_java_buffer(), "invariant");
 240   JfrBuffer* const buffer = tl->java_buffer();
 241   if (buffer == NULL) {
 242     JfrJavaSupport::throw_out_of_memory_error("OOME for thread local buffer", THREAD);
 243     return NULL;
 244   }
 245   jobject java_event_writer = create_new_event_writer(buffer, CHECK_NULL);
 246   tl->set_java_event_writer(java_event_writer);
 247   assert(tl->has_java_event_writer(), "invariant");
 248   return java_event_writer;
 249 }
--- EOF ---