1 /*
   2  * Copyright (c) 1997, 2019, 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 "gc/shared/collectedHeap.hpp"
  27 #include "gc/shared/collectedHeap.inline.hpp"
  28 #include "logging/log.hpp"
  29 #include "memory/resourceArea.hpp"
  30 #include "memory/universe.hpp"
  31 #include "runtime/atomic.hpp"
  32 #include "runtime/frame.inline.hpp"
  33 #include "runtime/handles.inline.hpp"
  34 #include "runtime/init.hpp"
  35 #include "runtime/interfaceSupport.inline.hpp"
  36 #include "runtime/orderAccess.hpp"
  37 #include "runtime/os.inline.hpp"
  38 #include "runtime/thread.inline.hpp"
  39 #include "runtime/safepointVerifiers.hpp"
  40 #include "runtime/vframe.hpp"
  41 #include "runtime/vmThread.hpp"
  42 #include "utilities/preserveException.hpp"
  43 
  44 // Implementation of InterfaceSupport
  45 
  46 #ifdef ASSERT
  47 VMEntryWrapper::VMEntryWrapper() {
  48   if (VerifyLastFrame) {
  49     InterfaceSupport::verify_last_frame();
  50   }
  51 }
  52 
  53 VMEntryWrapper::~VMEntryWrapper() {
  54   InterfaceSupport::check_gc_alot();
  55   if (WalkStackALot) {
  56     InterfaceSupport::walk_stack();
  57   }
  58 #ifdef COMPILER2
  59   // This option is not used by Compiler 1
  60   if (StressDerivedPointers) {
  61     InterfaceSupport::stress_derived_pointers();
  62   }
  63 #endif
  64   if (DeoptimizeALot || DeoptimizeRandom) {
  65     InterfaceSupport::deoptimizeAll();
  66   }
  67   if (ZombieALot) {
  68     InterfaceSupport::zombieAll();
  69   }
  70   // do verification AFTER potential deoptimization
  71   if (VerifyStack) {
  72     InterfaceSupport::verify_stack();
  73   }
  74 }
  75 
  76 long InterfaceSupport::_number_of_calls       = 0;
  77 long InterfaceSupport::_scavenge_alot_counter = 1;
  78 long InterfaceSupport::_fullgc_alot_counter   = 1;
  79 long InterfaceSupport::_fullgc_alot_invocation = 0;
  80 
  81 Histogram* RuntimeHistogram;
  82 
  83 RuntimeHistogramElement::RuntimeHistogramElement(const char* elementName) {
  84   static volatile int RuntimeHistogram_lock = 0;
  85   _name = elementName;
  86   uintx count = 0;
  87 
  88   while (Atomic::cmpxchg(1, &RuntimeHistogram_lock, 0) != 0) {
  89     while (OrderAccess::load_acquire(&RuntimeHistogram_lock) != 0) {
  90       count +=1;
  91       if ( (WarnOnStalledSpinLock > 0)
  92         && (count % WarnOnStalledSpinLock == 0)) {
  93         warning("RuntimeHistogram_lock seems to be stalled");
  94       }
  95     }
  96   }
  97 
  98   if (RuntimeHistogram == NULL) {
  99     RuntimeHistogram = new Histogram("VM Runtime Call Counts",200);
 100   }
 101 
 102   RuntimeHistogram->add_element(this);
 103   Atomic::dec(&RuntimeHistogram_lock);
 104 }
 105 
 106 void InterfaceSupport::gc_alot() {
 107   Thread *thread = Thread::current();
 108   if (!thread->is_Java_thread()) return; // Avoid concurrent calls
 109   // Check for new, not quite initialized thread. A thread in new mode cannot initiate a GC.
 110   JavaThread *current_thread = (JavaThread *)thread;
 111   if (current_thread->active_handles() == NULL) return;
 112 
 113   // Short-circuit any possible re-entrant gc-a-lot attempt
 114   if (thread->skip_gcalot()) return;
 115 
 116   if (Threads::is_vm_complete()) {
 117 
 118     if (++_fullgc_alot_invocation < FullGCALotStart) {
 119       return;
 120     }
 121 
 122     // Use this line if you want to block at a specific point,
 123     // e.g. one number_of_calls/scavenge/gc before you got into problems
 124     if (FullGCALot) _fullgc_alot_counter--;
 125 
 126     // Check if we should force a full gc
 127     if (_fullgc_alot_counter == 0) {
 128       // Release dummy so objects are forced to move
 129       if (!Universe::release_fullgc_alot_dummy()) {
 130         warning("FullGCALot: Unable to release more dummies at bottom of heap");
 131       }
 132       HandleMark hm(thread);
 133       Universe::heap()->collect(GCCause::_full_gc_alot);
 134       unsigned int invocations = Universe::heap()->total_full_collections();
 135       // Compute new interval
 136       if (FullGCALotInterval > 1) {
 137         _fullgc_alot_counter = 1+(long)((double)FullGCALotInterval*os::random()/(max_jint+1.0));
 138         log_trace(gc)("Full gc no: %u\tInterval: %ld", invocations, _fullgc_alot_counter);
 139       } else {
 140         _fullgc_alot_counter = 1;
 141       }
 142       // Print progress message
 143       if (invocations % 100 == 0) {
 144         log_trace(gc)("Full gc no: %u", invocations);
 145       }
 146     } else {
 147       if (ScavengeALot) _scavenge_alot_counter--;
 148       // Check if we should force a scavenge
 149       if (_scavenge_alot_counter == 0) {
 150         HandleMark hm(thread);
 151         Universe::heap()->collect(GCCause::_scavenge_alot);
 152         unsigned int invocations = Universe::heap()->total_collections() - Universe::heap()->total_full_collections();
 153         // Compute new interval
 154         if (ScavengeALotInterval > 1) {
 155           _scavenge_alot_counter = 1+(long)((double)ScavengeALotInterval*os::random()/(max_jint+1.0));
 156           log_trace(gc)("Scavenge no: %u\tInterval: %ld", invocations, _scavenge_alot_counter);
 157         } else {
 158           _scavenge_alot_counter = 1;
 159         }
 160         // Print progress message
 161         if (invocations % 1000 == 0) {
 162           log_trace(gc)("Scavenge no: %u", invocations);
 163         }
 164       }
 165     }
 166   }
 167 }
 168 
 169 
 170 vframe* vframe_array[50];
 171 int walk_stack_counter = 0;
 172 
 173 void InterfaceSupport::walk_stack_from(vframe* start_vf) {
 174   // walk
 175   int i = 0;
 176   for (vframe* f = start_vf; f; f = f->sender() ) {
 177     if (i < 50) vframe_array[i++] = f;
 178   }
 179 }
 180 
 181 
 182 void InterfaceSupport::walk_stack() {
 183   JavaThread* thread = JavaThread::current();
 184   walk_stack_counter++;
 185   if (!thread->has_last_Java_frame()) return;
 186   ResourceMark rm(thread);
 187   RegisterMap reg_map(thread);
 188   walk_stack_from(thread->last_java_vframe(&reg_map));
 189 }
 190 
 191 // invocation counter for InterfaceSupport::deoptimizeAll/zombieAll functions
 192 int deoptimizeAllCounter = 0;
 193 int zombieAllCounter = 0;
 194 
 195 void InterfaceSupport::zombieAll() {
 196   // This method is called by all threads when a thread make
 197   // transition to VM state (for example, runtime calls).
 198   // Divide number of calls by number of threads to avoid
 199   // dependence of ZombieAll events frequency on number of threads.
 200   int value = zombieAllCounter / Threads::number_of_threads();
 201   if (is_init_completed() && value > ZombieALotInterval) {
 202     zombieAllCounter = 0;
 203     VM_ZombieAll op;
 204     VMThread::execute(&op);
 205   }
 206   zombieAllCounter++;
 207 }
 208 
 209 void InterfaceSupport::deoptimizeAll() {
 210   // This method is called by all threads when a thread make
 211   // transition to VM state (for example, runtime calls).
 212   // Divide number of calls by number of threads to avoid
 213   // dependence of DeoptimizeAll events frequency on number of threads.
 214   int value = deoptimizeAllCounter / Threads::number_of_threads();
 215   if (is_init_completed()) {
 216     if (DeoptimizeALot && value > DeoptimizeALotInterval) {
 217       deoptimizeAllCounter = 0;
 218       VM_DeoptimizeAll op;
 219       VMThread::execute(&op);
 220     } else if (DeoptimizeRandom && (value & 0x1F) == (os::random() & 0x1F)) {
 221       VM_DeoptimizeAll op;
 222       VMThread::execute(&op);
 223     }
 224   }
 225   deoptimizeAllCounter++;
 226 }
 227 
 228 
 229 void InterfaceSupport::stress_derived_pointers() {
 230 #ifdef COMPILER2
 231   JavaThread *thread = JavaThread::current();
 232   if (!is_init_completed()) return;
 233   ResourceMark rm(thread);
 234   bool found = false;
 235   for (StackFrameStream sfs(thread); !sfs.is_done() && !found; sfs.next()) {
 236     CodeBlob* cb = sfs.current()->cb();
 237     if (cb != NULL && cb->oop_maps() ) {
 238       // Find oopmap for current method
 239       const ImmutableOopMap* map = cb->oop_map_for_return_address(sfs.current()->pc());
 240       assert(map != NULL, "no oopmap found for pc");
 241       found = map->has_derived_pointer();
 242     }
 243   }
 244   if (found) {
 245     // $$$ Not sure what to do here.
 246     /*
 247     Scavenge::invoke(0);
 248     */
 249   }
 250 #endif
 251 }
 252 
 253 
 254 void InterfaceSupport::verify_stack() {
 255   JavaThread* thread = JavaThread::current();
 256   ResourceMark rm(thread);
 257   // disabled because it throws warnings that oop maps should only be accessed
 258   // in VM thread or during debugging
 259 
 260   if (!thread->has_pending_exception()) {
 261     // verification does not work if there are pending exceptions
 262     StackFrameStream sfs(thread);
 263     CodeBlob* cb = sfs.current()->cb();
 264       // In case of exceptions we might not have a runtime_stub on
 265       // top of stack, hence, all callee-saved registers are not going
 266       // to be setup correctly, hence, we cannot do stack verify
 267     if (cb != NULL && !(cb->is_runtime_stub() || cb->is_uncommon_trap_stub())) return;
 268 
 269     for (; !sfs.is_done(); sfs.next()) {
 270       sfs.current()->verify(sfs.register_map());
 271     }
 272   }
 273 }
 274 
 275 
 276 void InterfaceSupport::verify_last_frame() {
 277   JavaThread* thread = JavaThread::current();
 278   ResourceMark rm(thread);
 279   RegisterMap reg_map(thread);
 280   frame fr = thread->last_frame();
 281   fr.verify(&reg_map);
 282 }
 283 
 284 
 285 #endif // ASSERT
 286 
 287 
 288 void InterfaceSupport_init() {
 289 #ifdef ASSERT
 290   if (ScavengeALot || FullGCALot) {
 291     srand(ScavengeALotInterval * FullGCALotInterval);
 292   }
 293 #endif
 294 }
 295 
 296 #ifdef ASSERT
 297 // JRT_LEAF rules:
 298 // A JRT_LEAF method may not interfere with safepointing by
 299 //   1) acquiring or blocking on a Mutex or JavaLock - checked
 300 //   2) allocating heap memory - checked
 301 //   3) executing a VM operation - checked
 302 //   4) executing a system call (including malloc) that could block or grab a lock
 303 //   5) invoking GC
 304 //   6) reaching a safepoint
 305 //   7) running too long
 306 // Nor may any method it calls.
 307 JRTLeafVerifier::JRTLeafVerifier()
 308   : NoSafepointVerifier(true, JRTLeafVerifier::should_verify_GC())
 309 {
 310 }
 311 
 312 JRTLeafVerifier::~JRTLeafVerifier()
 313 {
 314 }
 315 
 316 bool JRTLeafVerifier::should_verify_GC() {
 317   switch (JavaThread::current()->thread_state()) {
 318   case _thread_in_Java:
 319     // is in a leaf routine, there must be no safepoint.
 320     return true;
 321   case _thread_in_native:
 322     // A native thread is not subject to safepoints.
 323     // Even while it is in a leaf routine, GC is ok
 324     return false;
 325   default:
 326     // Leaf routines cannot be called from other contexts.
 327     ShouldNotReachHere();
 328     return false;
 329   }
 330 }
 331 #endif // ASSERT