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   CHECK_UNHANDLED_OOPS_ONLY(THREAD->clear_unhandled_oops();)
 147   assert(!HAS_PENDING_EXCEPTION, "Should not allocate with exception pending");
 148   debug_only(check_for_valid_allocation_state());
 149   assert(!Universe::heap()->is_gc_active(), "Allocation during gc not allowed");
 150 }
 151 
 152 void MemAllocator::Allocation::verify_after() {
 153   NOT_PRODUCT(check_for_bad_heap_word_value();)
 154 }
 155 
 156 void MemAllocator::Allocation::check_for_bad_heap_word_value() const {
 157   MemRegion obj_range = _allocator.obj_memory_range(obj());
 158   HeapWord* addr = obj_range.start();
 159   size_t size = obj_range.word_size();
 160   if (CheckMemoryInitialization && ZapUnusedHeapArea) {
 161     for (size_t slot = 0; slot < size; slot += 1) {
 162       assert((*(intptr_t*) (addr + slot)) != ((intptr_t) badHeapWordVal),
 163              "Found badHeapWordValue in post-allocation check");
 164     }
 165   }
 166 }
 167 
 168 #ifdef ASSERT
 169 void MemAllocator::Allocation::check_for_valid_allocation_state() const {
 170   // How to choose between a pending exception and a potential
 171   // OutOfMemoryError?  Don't allow pending exceptions.
 172   // This is a VM policy failure, so how do we exhaustively test it?
 173   assert(!_thread->has_pending_exception(),
 174          "shouldn't be allocating with pending exception");
 175   if (StrictSafepointChecks) {
 176     // Allocation of an oop can always invoke a safepoint,
 177     // hence, the true argument.
 178     _thread->check_for_valid_safepoint_state(true);
 179   }
 180 }
 181 #endif
 182 
 183 void MemAllocator::Allocation::notify_allocation_jvmti_sampler() {
 184   // support for JVMTI VMObjectAlloc event (no-op if not enabled)
 185   JvmtiExport::vm_object_alloc_event_collector(obj());
 186 
 187   if (!JvmtiExport::should_post_sampled_object_alloc()) {
 188     // Sampling disabled
 189     return;
 190   }
 191 
 192   if (!_allocated_outside_tlab && _allocated_tlab_size == 0 && !_tlab_end_reset_for_sample) {
 193     // Sample if it's a non-TLAB allocation, or a TLAB allocation that either refills the TLAB
 194     // or expands it due to taking a sampler induced slow path.
 195     return;
 196   }
 197 
 198   // If we want to be sampling, protect the allocated object with a Handle
 199   // before doing the callback. The callback is done in the destructor of
 200   // the JvmtiSampledObjectAllocEventCollector.
 201   size_t bytes_since_last = 0;
 202 
 203   {
 204     PreserveObj obj_h(_thread, _obj_ptr);
 205     JvmtiSampledObjectAllocEventCollector collector;
 206     size_t size_in_bytes = _allocator._word_size * HeapWordSize;
 207     ThreadLocalAllocBuffer& tlab = _thread->tlab();
 208 
 209     if (!_allocated_outside_tlab) {
 210       bytes_since_last = tlab.bytes_since_last_sample_point();
 211     }
 212 
 213     _thread->heap_sampler().check_for_sampling(obj_h(), size_in_bytes, bytes_since_last);
 214   }
 215 
 216   if (_tlab_end_reset_for_sample || _allocated_tlab_size != 0) {
 217     // Tell tlab to forget bytes_since_last if we passed it to the heap sampler.
 218     _thread->tlab().set_sample_end(bytes_since_last != 0);
 219   }
 220 }
 221 
 222 void MemAllocator::Allocation::notify_allocation_low_memory_detector() {
 223   // support low memory notifications (no-op if not enabled)
 224   LowMemoryDetector::detect_low_memory_for_collected_pools();
 225 }
 226 
 227 void MemAllocator::Allocation::notify_allocation_jfr_sampler() {
 228   HeapWord* mem = (HeapWord*)obj();
 229   size_t size_in_bytes = _allocator._word_size * HeapWordSize;
 230 
 231   if (_allocated_outside_tlab) {
 232     AllocTracer::send_allocation_outside_tlab(obj()->klass(), mem, size_in_bytes, _thread);
 233   } else if (_allocated_tlab_size != 0) {
 234     // TLAB was refilled
 235     AllocTracer::send_allocation_in_new_tlab(obj()->klass(), mem, _allocated_tlab_size * HeapWordSize,
 236                                              size_in_bytes, _thread);
 237   }
 238 }
 239 
 240 void MemAllocator::Allocation::notify_allocation_dtrace_sampler() {
 241   if (DTraceAllocProbes) {
 242     // support for Dtrace object alloc event (no-op most of the time)
 243     Klass* klass = obj()->klass();
 244     size_t word_size = _allocator._word_size;
 245     if (klass != NULL && klass->name() != NULL) {
 246       SharedRuntime::dtrace_object_alloc(obj(), (int)word_size);
 247     }
 248   }
 249 }
 250 
 251 void MemAllocator::Allocation::notify_allocation() {
 252   notify_allocation_low_memory_detector();
 253   notify_allocation_jfr_sampler();
 254   notify_allocation_dtrace_sampler();
 255   notify_allocation_jvmti_sampler();
 256 }
 257 
 258 HeapWord* MemAllocator::allocate_outside_tlab(Allocation& allocation) const {
 259   allocation._allocated_outside_tlab = true;
 260   HeapWord* mem = Universe::heap()->mem_allocate(_word_size, &allocation._overhead_limit_exceeded);
 261   if (mem == NULL) {
 262     return mem;
 263   }
 264 
 265   NOT_PRODUCT(Universe::heap()->check_for_non_bad_heap_word_value(mem, _word_size));
 266   size_t size_in_bytes = _word_size * HeapWordSize;
 267   _thread->incr_allocated_bytes(size_in_bytes);
 268 
 269   return mem;
 270 }
 271 
 272 HeapWord* MemAllocator::allocate_inside_tlab(Allocation& allocation) const {
 273   assert(UseTLAB, "should use UseTLAB");
 274 
 275   // Try allocating from an existing TLAB.
 276   HeapWord* mem = _thread->tlab().allocate(_word_size);
 277   if (mem != NULL) {
 278     return mem;
 279   }
 280 
 281   // Try refilling the TLAB and allocating the object in it.
 282   return allocate_inside_tlab_slow(allocation);
 283 }
 284 
 285 HeapWord* MemAllocator::allocate_inside_tlab_slow(Allocation& allocation) const {
 286   HeapWord* mem = NULL;
 287   ThreadLocalAllocBuffer& tlab = _thread->tlab();
 288 
 289   if (JvmtiExport::should_post_sampled_object_alloc()) {
 290     tlab.set_back_allocation_end();
 291     mem = tlab.allocate(_word_size);
 292 
 293     // We set back the allocation sample point to try to allocate this, reset it
 294     // when done.
 295     allocation._tlab_end_reset_for_sample = true;
 296 
 297     if (mem != NULL) {
 298       return mem;
 299     }
 300   }
 301 
 302   // Retain tlab and allocate object in shared space if
 303   // the amount free in the tlab is too large to discard.
 304   if (tlab.free() > tlab.refill_waste_limit()) {
 305     tlab.record_slow_allocation(_word_size);
 306     return NULL;
 307   }
 308 
 309   // Discard tlab and allocate a new one.
 310   // To minimize fragmentation, the last TLAB may be smaller than the rest.
 311   size_t new_tlab_size = tlab.compute_size(_word_size);
 312 
 313   tlab.retire_before_allocation();
 314 
 315   if (new_tlab_size == 0) {
 316     return NULL;
 317   }
 318 
 319   // Allocate a new TLAB requesting new_tlab_size. Any size
 320   // between minimal and new_tlab_size is accepted.
 321   size_t min_tlab_size = ThreadLocalAllocBuffer::compute_min_size(_word_size);
 322   mem = Universe::heap()->allocate_new_tlab(min_tlab_size, new_tlab_size, &allocation._allocated_tlab_size);
 323   if (mem == NULL) {
 324     assert(allocation._allocated_tlab_size == 0,
 325            "Allocation failed, but actual size was updated. min: " SIZE_FORMAT
 326            ", desired: " SIZE_FORMAT ", actual: " SIZE_FORMAT,
 327            min_tlab_size, new_tlab_size, allocation._allocated_tlab_size);
 328     return NULL;
 329   }
 330   assert(allocation._allocated_tlab_size != 0, "Allocation succeeded but actual size not updated. mem at: "
 331          PTR_FORMAT " min: " SIZE_FORMAT ", desired: " SIZE_FORMAT,
 332          p2i(mem), min_tlab_size, new_tlab_size);
 333 
 334   if (ZeroTLAB) {
 335     // ..and clear it.
 336     Copy::zero_to_words(mem, allocation._allocated_tlab_size);
 337   } else {
 338     // ...and zap just allocated object.
 339 #ifdef ASSERT
 340     // Skip mangling the space corresponding to the object header to
 341     // ensure that the returned space is not considered parsable by
 342     // any concurrent GC thread.
 343     size_t hdr_size = oopDesc::header_size();
 344     Copy::fill_to_words(mem + hdr_size, allocation._allocated_tlab_size - hdr_size, badHeapWordVal);
 345 #endif // ASSERT
 346   }
 347 
 348   tlab.fill(mem, mem + _word_size, allocation._allocated_tlab_size);
 349   return mem;
 350 }
 351 
 352 HeapWord* MemAllocator::mem_allocate(Allocation& allocation) const {
 353   if (UseTLAB) {
 354     HeapWord* result = allocate_inside_tlab(allocation);
 355     if (result != NULL) {
 356       return result;
 357     }
 358   }
 359 
 360   return allocate_outside_tlab(allocation);
 361 }
 362 
 363 oop MemAllocator::allocate() const {
 364   oop obj = NULL;
 365   {
 366     Allocation allocation(*this, &obj);
 367     HeapWord* mem = mem_allocate(allocation);
 368     if (mem != NULL) {
 369       obj = initialize(mem);
 370     } else {
 371       // The unhandled oop detector will poison local variable obj,
 372       // so reset it to NULL if mem is NULL.
 373       obj = NULL;
 374     }
 375   }
 376   return obj;
 377 }
 378 
 379 void MemAllocator::mem_clear(HeapWord* mem) const {
 380   assert(mem != NULL, "cannot initialize NULL object");
 381   const size_t hs = oopDesc::header_size();
 382   assert(_word_size >= hs, "unexpected object size");
 383   oopDesc::set_klass_gap(mem, 0);
 384   Copy::fill_to_aligned_words(mem + hs, _word_size - hs);
 385 }
 386 
 387 oop MemAllocator::finish(HeapWord* mem) const {
 388   assert(mem != NULL, "NULL object pointer");
 389   if (UseBiasedLocking) {
 390     oopDesc::set_mark_raw(mem, _klass->prototype_header());
 391   } else {
 392     // May be bootstrapping
 393     oopDesc::set_mark_raw(mem, markOopDesc::prototype());
 394   }
 395   // Need a release store to ensure array/class length, mark word, and
 396   // object zeroing are visible before setting the klass non-NULL, for
 397   // concurrent collectors.
 398   oopDesc::release_set_klass(mem, _klass);
 399   return oop(mem);
 400 }
 401 
 402 oop ObjAllocator::initialize(HeapWord* mem) const {
 403   mem_clear(mem);
 404   return finish(mem);
 405 }
 406 
 407 MemRegion ObjArrayAllocator::obj_memory_range(oop obj) const {
 408   if (_do_zero) {
 409     return MemAllocator::obj_memory_range(obj);
 410   }
 411   ArrayKlass* array_klass = ArrayKlass::cast(_klass);
 412   const size_t hs = arrayOopDesc::header_size(array_klass->element_type());
 413   return MemRegion(((HeapWord*)obj) + hs, _word_size - hs);
 414 }
 415 
 416 oop ObjArrayAllocator::initialize(HeapWord* mem) const {
 417   // Set array length before setting the _klass field because a
 418   // non-NULL klass field indicates that the object is parsable by
 419   // concurrent GC.
 420   assert(_length >= 0, "length should be non-negative");
 421   if (_do_zero) {
 422     mem_clear(mem);
 423   }
 424   arrayOopDesc::set_length(mem, _length);
 425   return finish(mem);
 426 }
 427 
 428 oop ClassAllocator::initialize(HeapWord* mem) const {
 429   // Set oop_size field before setting the _klass field because a
 430   // non-NULL _klass field indicates that the object is parsable by
 431   // concurrent GC.
 432   assert(_word_size > 0, "oop_size must be positive.");
 433   mem_clear(mem);
 434   java_lang_Class::set_oop_size(mem, (int)_word_size);
 435   return finish(mem);
 436 }