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