1 /*
   2  * Copyright (c) 2018, 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 "classfile/javaClasses.hpp"
  27 #include "gc/shared/allocTracer.hpp"
  28 #include "gc/shared/collectedHeap.hpp"
  29 #include "gc/shared/memAllocator.hpp"
  30 #include "gc/shared/threadLocalAllocBuffer.inline.hpp"
  31 #include "memory/universe.hpp"
  32 #include "oops/arrayOop.hpp"
  33 #include "oops/oop.inline.hpp"
  34 #include "prims/jvmtiExport.hpp"
  35 #include "runtime/sharedRuntime.hpp"
  36 #include "runtime/handles.inline.hpp"
  37 #include "runtime/thread.inline.hpp"
  38 #include "services/lowMemoryDetector.hpp"
  39 #include "utilities/align.hpp"
  40 #include "utilities/copy.hpp"
  41 
  42 class MemAllocator::Allocation: StackObj {
  43   friend class MemAllocator;
  44 
  45   const MemAllocator& _allocator;
  46   Thread*             _thread;
  47   oop*                _obj_ptr;
  48   bool                _overhead_limit_exceeded;
  49   bool                _allocated_outside_tlab;
  50   size_t              _allocated_tlab_size;
  51   bool                _tlab_end_reset_for_sample;
  52 
  53   bool check_out_of_memory();
  54   void verify_before();
  55   void verify_after();
  56   void notify_allocation();
  57   void notify_allocation_jvmti_allocation_event();
  58   void notify_allocation_jvmti_sampler();
  59   void notify_allocation_low_memory_detector();
  60   void notify_allocation_jfr_sampler();
  61   void notify_allocation_dtrace_sampler();
  62   void check_for_bad_heap_word_value() const;
  63 #ifdef ASSERT
  64   void check_for_valid_allocation_state() const;
  65 #endif
  66 
  67   class PreserveObj;
  68 
  69 public:
  70   Allocation(const MemAllocator& allocator, oop* obj_ptr)
  71     : _allocator(allocator),
  72       _thread(Thread::current()),
  73       _obj_ptr(obj_ptr),
  74       _overhead_limit_exceeded(false),
  75       _allocated_outside_tlab(false),
  76       _allocated_tlab_size(0),
  77       _tlab_end_reset_for_sample(false)
  78   {
  79     verify_before();
  80   }
  81 
  82   ~Allocation() {
  83     if (!check_out_of_memory()) {
  84       verify_after();
  85       notify_allocation();
  86     }
  87   }
  88 
  89   oop obj() const { return *_obj_ptr; }
  90 };
  91 
  92 class MemAllocator::Allocation::PreserveObj: StackObj {
  93   HandleMark _handle_mark;
  94   Handle     _handle;
  95   oop* const _obj_ptr;
  96 
  97 public:
  98   PreserveObj(Thread* thread, oop* obj_ptr)
  99     : _handle_mark(thread),
 100       _handle(thread, *obj_ptr),
 101       _obj_ptr(obj_ptr)
 102   {
 103     *obj_ptr = NULL;
 104   }
 105 
 106   ~PreserveObj() {
 107     *_obj_ptr = _handle();
 108   }
 109 
 110   oop operator()() const {
 111     return _handle();
 112   }
 113 };
 114 
 115 bool MemAllocator::Allocation::check_out_of_memory() {
 116   Thread* THREAD = _thread;
 117   assert(!HAS_PENDING_EXCEPTION, "Unexpected exception, will result in uninitialized storage");
 118 
 119   if (obj() != NULL) {
 120     return false;
 121   }
 122 
 123   const char* message = _overhead_limit_exceeded ? "GC overhead limit exceeded" : "Java heap space";
 124   if (!THREAD->in_retryable_allocation()) {
 125     // -XX:+HeapDumpOnOutOfMemoryError and -XX:OnOutOfMemoryError support
 126     report_java_out_of_memory(message);
 127 
 128     if (JvmtiExport::should_post_resource_exhausted()) {
 129       JvmtiExport::post_resource_exhausted(
 130         JVMTI_RESOURCE_EXHAUSTED_OOM_ERROR | JVMTI_RESOURCE_EXHAUSTED_JAVA_HEAP,
 131         message);
 132     }
 133     oop exception = _overhead_limit_exceeded ?
 134         Universe::out_of_memory_error_gc_overhead_limit() :
 135         Universe::out_of_memory_error_java_heap();
 136     THROW_OOP_(exception, true);
 137   } else {
 138     THROW_OOP_(Universe::out_of_memory_error_retry(), true);
 139   }
 140 }
 141 
 142 void MemAllocator::Allocation::verify_before() {
 143   // Clear unhandled oops for memory allocation.  Memory allocation might
 144   // not take out a lock if from tlab, so clear here.
 145   Thread* THREAD = _thread;
 146   assert(!HAS_PENDING_EXCEPTION, "Should not allocate with exception pending");
 147   debug_only(check_for_valid_allocation_state());
 148   assert(!Universe::heap()->is_gc_active(), "Allocation during gc not allowed");
 149 }
 150 
 151 void MemAllocator::Allocation::verify_after() {
 152   NOT_PRODUCT(check_for_bad_heap_word_value();)
 153 }
 154 
 155 void MemAllocator::Allocation::check_for_bad_heap_word_value() const {
 156   MemRegion obj_range = _allocator.obj_memory_range(obj());
 157   HeapWord* addr = obj_range.start();
 158   size_t size = obj_range.word_size();
 159   if (CheckMemoryInitialization && ZapUnusedHeapArea) {
 160     for (size_t slot = 0; slot < size; slot += 1) {
 161       assert((*(intptr_t*) (addr + slot)) != ((intptr_t) badHeapWordVal),
 162              "Found badHeapWordValue in post-allocation check");
 163     }
 164   }
 165 }
 166 
 167 #ifdef ASSERT
 168 void MemAllocator::Allocation::check_for_valid_allocation_state() const {
 169   // How to choose between a pending exception and a potential
 170   // OutOfMemoryError?  Don't allow pending exceptions.
 171   // This is a VM policy failure, so how do we exhaustively test it?
 172   assert(!_thread->has_pending_exception(),
 173          "shouldn't be allocating with pending exception");
 174   // Allocation of an oop can always invoke a safepoint.
 175   _thread->check_for_valid_safepoint_state();
 176 }
 177 #endif
 178 
 179 void MemAllocator::Allocation::notify_allocation_jvmti_sampler() {
 180   // support for JVMTI VMObjectAlloc event (no-op if not enabled)
 181   JvmtiExport::vm_object_alloc_event_collector(obj());
 182 
 183   if (!JvmtiExport::should_post_sampled_object_alloc()) {
 184     // Sampling disabled
 185     return;
 186   }
 187 
 188   if (!_allocated_outside_tlab && _allocated_tlab_size == 0 && !_tlab_end_reset_for_sample) {
 189     // Sample if it's a non-TLAB allocation, or a TLAB allocation that either refills the TLAB
 190     // or expands it due to taking a sampler induced slow path.
 191     return;
 192   }
 193 
 194   // If we want to be sampling, protect the allocated object with a Handle
 195   // before doing the callback. The callback is done in the destructor of
 196   // the JvmtiSampledObjectAllocEventCollector.
 197   size_t bytes_since_last = 0;
 198 
 199   {
 200     PreserveObj obj_h(_thread, _obj_ptr);
 201     JvmtiSampledObjectAllocEventCollector collector;
 202     size_t size_in_bytes = _allocator._word_size * HeapWordSize;
 203     ThreadLocalAllocBuffer& tlab = _thread->tlab();
 204 
 205     if (!_allocated_outside_tlab) {
 206       bytes_since_last = tlab.bytes_since_last_sample_point();
 207     }
 208 
 209     _thread->heap_sampler().check_for_sampling(obj_h(), size_in_bytes, bytes_since_last);
 210   }
 211 
 212   if (_tlab_end_reset_for_sample || _allocated_tlab_size != 0) {
 213     // Tell tlab to forget bytes_since_last if we passed it to the heap sampler.
 214     _thread->tlab().set_sample_end(bytes_since_last != 0);
 215   }
 216 }
 217 
 218 void MemAllocator::Allocation::notify_allocation_low_memory_detector() {
 219   // support low memory notifications (no-op if not enabled)
 220   LowMemoryDetector::detect_low_memory_for_collected_pools();
 221 }
 222 
 223 void MemAllocator::Allocation::notify_allocation_jfr_sampler() {
 224   HeapWord* mem = (HeapWord*)obj();
 225   size_t size_in_bytes = _allocator._word_size * HeapWordSize;
 226 
 227   if (_allocated_outside_tlab) {
 228     AllocTracer::send_allocation_outside_tlab(obj()->klass(), mem, size_in_bytes, _thread);
 229   } else if (_allocated_tlab_size != 0) {
 230     // TLAB was refilled
 231     AllocTracer::send_allocation_in_new_tlab(obj()->klass(), mem, _allocated_tlab_size * HeapWordSize,
 232                                              size_in_bytes, _thread);
 233   }
 234 }
 235 
 236 void MemAllocator::Allocation::notify_allocation_dtrace_sampler() {
 237   if (DTraceAllocProbes) {
 238     // support for Dtrace object alloc event (no-op most of the time)
 239     Klass* klass = obj()->klass();
 240     size_t word_size = _allocator._word_size;
 241     if (klass != NULL && klass->name() != NULL) {
 242       SharedRuntime::dtrace_object_alloc(obj(), (int)word_size);
 243     }
 244   }
 245 }
 246 
 247 void MemAllocator::Allocation::notify_allocation() {
 248   notify_allocation_low_memory_detector();
 249   notify_allocation_jfr_sampler();
 250   notify_allocation_dtrace_sampler();
 251   notify_allocation_jvmti_sampler();
 252 }
 253 
 254 HeapWord* MemAllocator::allocate_outside_tlab(Allocation& allocation) const {
 255   allocation._allocated_outside_tlab = true;
 256   HeapWord* mem = Universe::heap()->mem_allocate(_word_size, &allocation._overhead_limit_exceeded);
 257   if (mem == NULL) {
 258     return mem;
 259   }
 260 
 261   NOT_PRODUCT(Universe::heap()->check_for_non_bad_heap_word_value(mem, _word_size));
 262   size_t size_in_bytes = _word_size * HeapWordSize;
 263   _thread->incr_allocated_bytes(size_in_bytes);
 264 
 265   return mem;
 266 }
 267 
 268 HeapWord* MemAllocator::allocate_inside_tlab(Allocation& allocation) const {
 269   assert(UseTLAB, "should use UseTLAB");
 270 
 271   // Try allocating from an existing TLAB.
 272   HeapWord* mem = _thread->tlab().allocate(_word_size);
 273   if (mem != NULL) {
 274     return mem;
 275   }
 276 
 277   // Try refilling the TLAB and allocating the object in it.
 278   return allocate_inside_tlab_slow(allocation);
 279 }
 280 
 281 HeapWord* MemAllocator::allocate_inside_tlab_slow(Allocation& allocation) const {
 282   HeapWord* mem = NULL;
 283   ThreadLocalAllocBuffer& tlab = _thread->tlab();
 284 
 285   if (JvmtiExport::should_post_sampled_object_alloc()) {
 286     tlab.set_back_allocation_end();
 287     mem = tlab.allocate(_word_size);
 288 
 289     // We set back the allocation sample point to try to allocate this, reset it
 290     // when done.
 291     allocation._tlab_end_reset_for_sample = true;
 292 
 293     if (mem != NULL) {
 294       return mem;
 295     }
 296   }
 297 
 298   // Retain tlab and allocate object in shared space if
 299   // the amount free in the tlab is too large to discard.
 300   if (tlab.free() > tlab.refill_waste_limit()) {
 301     tlab.record_slow_allocation(_word_size);
 302     return NULL;
 303   }
 304 
 305   // Discard tlab and allocate a new one.
 306   // To minimize fragmentation, the last TLAB may be smaller than the rest.
 307   size_t new_tlab_size = tlab.compute_size(_word_size);
 308 
 309   tlab.retire_before_allocation();
 310 
 311   if (new_tlab_size == 0) {
 312     return NULL;
 313   }
 314 
 315   // Allocate a new TLAB requesting new_tlab_size. Any size
 316   // between minimal and new_tlab_size is accepted.
 317   size_t min_tlab_size = ThreadLocalAllocBuffer::compute_min_size(_word_size);
 318   mem = Universe::heap()->allocate_new_tlab(min_tlab_size, new_tlab_size, &allocation._allocated_tlab_size);
 319   if (mem == NULL) {
 320     assert(allocation._allocated_tlab_size == 0,
 321            "Allocation failed, but actual size was updated. min: " SIZE_FORMAT
 322            ", desired: " SIZE_FORMAT ", actual: " SIZE_FORMAT,
 323            min_tlab_size, new_tlab_size, allocation._allocated_tlab_size);
 324     return NULL;
 325   }
 326   assert(allocation._allocated_tlab_size != 0, "Allocation succeeded but actual size not updated. mem at: "
 327          PTR_FORMAT " min: " SIZE_FORMAT ", desired: " SIZE_FORMAT,
 328          p2i(mem), min_tlab_size, new_tlab_size);
 329 
 330   if (ZeroTLAB) {
 331     // ..and clear it.
 332     Copy::zero_to_words(mem, allocation._allocated_tlab_size);
 333   } else {
 334     // ...and zap just allocated object.
 335 #ifdef ASSERT
 336     // Skip mangling the space corresponding to the object header to
 337     // ensure that the returned space is not considered parsable by
 338     // any concurrent GC thread.
 339     size_t hdr_size = oopDesc::header_size();
 340     Copy::fill_to_words(mem + hdr_size, allocation._allocated_tlab_size - hdr_size, badHeapWordVal);
 341 #endif // ASSERT
 342   }
 343 
 344   tlab.fill(mem, mem + _word_size, allocation._allocated_tlab_size);
 345   return mem;
 346 }
 347 
 348 HeapWord* MemAllocator::mem_allocate(Allocation& allocation) const {
 349   if (UseTLAB) {
 350     HeapWord* result = allocate_inside_tlab(allocation);
 351     if (result != NULL) {
 352       return result;
 353     }
 354   }
 355 
 356   return allocate_outside_tlab(allocation);
 357 }
 358 
 359 oop MemAllocator::allocate() const {
 360   oop obj = NULL;
 361   {
 362     Allocation allocation(*this, &obj);
 363     HeapWord* mem = mem_allocate(allocation);
 364     if (mem != NULL) {
 365       obj = initialize(mem);
 366     } else {
 367       // The unhandled oop detector will poison local variable obj,
 368       // so reset it to NULL if mem is NULL.
 369       obj = NULL;
 370     }
 371   }
 372   return obj;
 373 }
 374 
 375 void MemAllocator::mem_clear(HeapWord* mem) const {
 376   assert(mem != NULL, "cannot initialize NULL object");
 377   const size_t hs = oopDesc::header_size();
 378   assert(_word_size >= hs, "unexpected object size");
 379   oopDesc::set_klass_gap(mem, 0);
 380   Copy::fill_to_aligned_words(mem + hs, _word_size - hs);
 381 }
 382 
 383 oop MemAllocator::finish(HeapWord* mem) const {
 384   assert(mem != NULL, "NULL object pointer");
 385   oopDesc::set_mark_raw(mem, Klass::default_prototype_header(_klass));
 386   // Need a release store to ensure array/class length, mark word, and
 387   // object zeroing are visible before setting the klass non-NULL, for
 388   // concurrent collectors.
 389   oopDesc::release_set_klass(mem, _klass);
 390   return oop(mem);
 391 }
 392 
 393 oop MemAllocator::finish_with_properties(HeapWord* mem, ArrayStorageProperties storage_props) const {
 394   finish(mem);
 395   oopDesc::release_set_metadata(mem, storage_props, _klass);
 396   return oop(mem);
 397 }
 398 
 399 oop ObjAllocator::initialize(HeapWord* mem) const {
 400   mem_clear(mem);
 401   return finish(mem);
 402 }
 403 
 404 oop ObjBufferAllocator::initialize(HeapWord* mem) const {
 405   oopDesc::set_klass_gap(mem, 0);
 406   return finish(mem);
 407 }
 408 
 409 
 410 MemRegion ObjArrayAllocator::obj_memory_range(oop obj) const {
 411   if (_do_zero) {
 412     return MemAllocator::obj_memory_range(obj);
 413   }
 414   ArrayKlass* array_klass = ArrayKlass::cast(_klass);
 415   const size_t hs = arrayOopDesc::header_size(array_klass->element_type());
 416   return MemRegion(((HeapWord*)obj) + hs, _word_size - hs);
 417 }
 418 
 419 oop ObjArrayAllocator::initialize(HeapWord* mem) const {
 420   // Set array length before setting the _klass field because a
 421   // non-NULL klass field indicates that the object is parsable by
 422   // concurrent GC.
 423   assert(_length >= 0, "length should be non-negative");
 424   if (_do_zero) {
 425     mem_clear(mem);
 426   }
 427   arrayOopDesc::set_length(mem, _length);
 428   assert(ArrayKlass::cast(_klass)->storage_properties().is_empty() ||
 429       ArrayKlass::cast(_klass)->dimension() == 1, "Multidim should have no storage props");
 430   return finish_with_properties(mem, ArrayKlass::cast(_klass)->storage_properties());
 431 }
 432 
 433 oop ClassAllocator::initialize(HeapWord* mem) const {
 434   // Set oop_size field before setting the _klass field because a
 435   // non-NULL _klass field indicates that the object is parsable by
 436   // concurrent GC.
 437   assert(_word_size > 0, "oop_size must be positive.");
 438   mem_clear(mem);
 439   java_lang_Class::set_oop_size(mem, (int)_word_size);
 440   return finish(mem);
 441 }