--- a/src/hotspot/share/prims/unsafe.cpp Mon Nov 20 12:04:13 2017 +0100
+++ b/src/hotspot/share/prims/unsafe.cpp Mon Nov 20 13:07:44 2017 +0100
@@ -29,6 +29,7 @@
#include "classfile/vmSymbols.hpp"
#include "memory/allocation.inline.hpp"
#include "memory/resourceArea.hpp"
+#include "oops/access.inline.hpp"
#include "oops/fieldStreams.hpp"
#include "oops/objArrayOop.inline.hpp"
#include "oops/oop.inline.hpp"
@@ -45,9 +46,6 @@
#include "utilities/copy.hpp"
#include "utilities/dtrace.hpp"
#include "utilities/macros.hpp"
-#if INCLUDE_ALL_GCS
-#include "gc/g1/g1SATBCardTableModRefBS.hpp"
-#endif // INCLUDE_ALL_GCS
/**
* Implementation of the jdk.internal.misc.Unsafe class
@@ -100,10 +98,10 @@
return byte_offset;
}
-static inline void* index_oop_from_field_offset_long(oop p, jlong field_offset) {
+static inline void assert_field_offset_sane(oop p, jlong field_offset) {
+#ifdef ASSERT
jlong byte_offset = field_offset_to_byte_offset(field_offset);
-#ifdef ASSERT
if (p != NULL) {
assert(byte_offset >= 0 && byte_offset <= (jlong)MAX_OBJECT_SIZE, "sane offset");
if (byte_offset == (jint)byte_offset) {
@@ -115,6 +113,11 @@
assert(byte_offset < p_size, "Unsafe access: offset " INT64_FORMAT " > object's size " INT64_FORMAT, (int64_t)byte_offset, (int64_t)p_size);
}
#endif
+}
+
+static inline void* index_oop_from_field_offset_long(oop p, jlong field_offset) {
+ assert_field_offset_sane(p, field_offset);
+ jlong byte_offset = field_offset_to_byte_offset(field_offset);
if (sizeof(char*) == sizeof(jint)) { // (this constant folds!)
return (address)p + (jint) byte_offset;
@@ -143,12 +146,12 @@
*/
class MemoryAccess : StackObj {
JavaThread* _thread;
- jobject _obj;
- jlong _offset;
+ oop _obj;
+ ptrdiff_t _offset;
// Resolves and returns the address of the memory access
void* addr() {
- return index_oop_from_field_offset_long(JNIHandles::resolve(_obj), _offset);
+ return index_oop_from_field_offset_long(_obj, _offset);
}
template <typename T>
@@ -174,252 +177,108 @@
*/
class GuardUnsafeAccess {
JavaThread* _thread;
- bool _active;
public:
- GuardUnsafeAccess(JavaThread* thread, jobject _obj) : _thread(thread) {
- if (JNIHandles::resolve(_obj) == NULL) {
- // native/off-heap access which may raise SIGBUS if accessing
- // memory mapped file data in a region of the file which has
- // been truncated and is now invalid
- _thread->set_doing_unsafe_access(true);
- _active = true;
- } else {
- _active = false;
- }
+ GuardUnsafeAccess(JavaThread* thread) : _thread(thread) {
+ // native/off-heap access which may raise SIGBUS if accessing
+ // memory mapped file data in a region of the file which has
+ // been truncated and is now invalid
+ _thread->set_doing_unsafe_access(true);
}
~GuardUnsafeAccess() {
- if (_active) {
- _thread->set_doing_unsafe_access(false);
- }
+ _thread->set_doing_unsafe_access(false);
}
};
public:
MemoryAccess(JavaThread* thread, jobject obj, jlong offset)
- : _thread(thread), _obj(obj), _offset(offset) {
+ : _thread(thread), _obj(JNIHandles::resolve(obj)), _offset((ptrdiff_t)offset) {
+ assert_field_offset_sane(_obj, offset);
}
template <typename T>
T get() {
- GuardUnsafeAccess guard(_thread, _obj);
-
- T* p = (T*)addr();
-
- T x = normalize_for_read(*p);
-
- return x;
+ if (oopDesc::is_null(_obj)) {
+ GuardUnsafeAccess guard(_thread);
+ T ret = RawAccess<>::load((T*)addr());
+ return normalize_for_read(ret);
+ } else {
+ T ret = HeapAccess<>::load_at(_obj, _offset);
+ return normalize_for_read(ret);
+ }
}
template <typename T>
void put(T x) {
- GuardUnsafeAccess guard(_thread, _obj);
-
- T* p = (T*)addr();
-
- *p = normalize_for_write(x);
+ if (oopDesc::is_null(_obj)) {
+ GuardUnsafeAccess guard(_thread);
+ RawAccess<>::store((T*)addr(), normalize_for_write(x));
+ } else {
+ HeapAccess<>::store_at(_obj, _offset, normalize_for_write(x));
+ }
}
template <typename T>
T get_volatile() {
- GuardUnsafeAccess guard(_thread, _obj);
-
- T* p = (T*)addr();
-
- if (support_IRIW_for_not_multiple_copy_atomic_cpu) {
- OrderAccess::fence();
+ if (oopDesc::is_null(_obj)) {
+ GuardUnsafeAccess guard(_thread);
+ volatile T ret = RawAccess<MO_SEQ_CST>::load((volatile T*)addr());
+ return normalize_for_read(ret);
+ } else {
+ T ret = HeapAccess<MO_SEQ_CST>::load_at(_obj, _offset);
+ return normalize_for_read(ret);
}
-
- T x = OrderAccess::load_acquire((volatile T*)p);
-
- return normalize_for_read(x);
}
template <typename T>
void put_volatile(T x) {
- GuardUnsafeAccess guard(_thread, _obj);
-
- T* p = (T*)addr();
-
- OrderAccess::release_store_fence((volatile T*)p, normalize_for_write(x));
- }
-
-
-#ifndef SUPPORTS_NATIVE_CX8
- jlong get_jlong_locked() {
- GuardUnsafeAccess guard(_thread, _obj);
-
- MutexLockerEx mu(UnsafeJlong_lock, Mutex::_no_safepoint_check_flag);
-
- jlong* p = (jlong*)addr();
-
- jlong x = Atomic::load(p);
-
- return x;
- }
-
- void put_jlong_locked(jlong x) {
- GuardUnsafeAccess guard(_thread, _obj);
-
- MutexLockerEx mu(UnsafeJlong_lock, Mutex::_no_safepoint_check_flag);
-
- jlong* p = (jlong*)addr();
-
- Atomic::store(normalize_for_write(x), p);
- }
-#endif
-};
-
-// Get/PutObject must be special-cased, since it works with handles.
-
-// We could be accessing the referent field in a reference
-// object. If G1 is enabled then we need to register non-null
-// referent with the SATB barrier.
-
-#if INCLUDE_ALL_GCS
-static bool is_java_lang_ref_Reference_access(oop o, jlong offset) {
- if (offset == java_lang_ref_Reference::referent_offset && o != NULL) {
- Klass* k = o->klass();
- if (InstanceKlass::cast(k)->reference_type() != REF_NONE) {
- assert(InstanceKlass::cast(k)->is_subclass_of(SystemDictionary::Reference_klass()), "sanity");
- return true;
+ if (oopDesc::is_null(_obj)) {
+ GuardUnsafeAccess guard(_thread);
+ RawAccess<MO_SEQ_CST>::store((volatile T*)addr(), normalize_for_write(x));
+ } else {
+ HeapAccess<MO_SEQ_CST>::store_at(_obj, _offset, normalize_for_write(x));
}
}
- return false;
-}
-#endif
-
-static void ensure_satb_referent_alive(oop o, jlong offset, oop v) {
-#if INCLUDE_ALL_GCS
- if (UseG1GC && v != NULL && is_java_lang_ref_Reference_access(o, offset)) {
- G1SATBCardTableModRefBS::enqueue(v);
- }
-#endif
-}
+};
// These functions allow a null base pointer with an arbitrary address.
// But if the base pointer is non-null, the offset should make some sense.
// That is, it should be in the range [0, MAX_OBJECT_SIZE].
UNSAFE_ENTRY(jobject, Unsafe_GetObject(JNIEnv *env, jobject unsafe, jobject obj, jlong offset)) {
oop p = JNIHandles::resolve(obj);
- oop v;
-
- if (UseCompressedOops) {
- narrowOop n = *(narrowOop*)index_oop_from_field_offset_long(p, offset);
- v = oopDesc::decode_heap_oop(n);
- } else {
- v = *(oop*)index_oop_from_field_offset_long(p, offset);
- }
-
- ensure_satb_referent_alive(p, offset, v);
-
+ assert_field_offset_sane(p, offset);
+ oop v = HeapAccess<ON_UNKNOWN_OOP_REF>::oop_load_at(p, offset);
return JNIHandles::make_local(env, v);
} UNSAFE_END
UNSAFE_ENTRY(void, Unsafe_PutObject(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jobject x_h)) {
oop x = JNIHandles::resolve(x_h);
oop p = JNIHandles::resolve(obj);
-
- if (UseCompressedOops) {
- oop_store((narrowOop*)index_oop_from_field_offset_long(p, offset), x);
- } else {
- oop_store((oop*)index_oop_from_field_offset_long(p, offset), x);
- }
+ assert_field_offset_sane(p, offset);
+ HeapAccess<ON_UNKNOWN_OOP_REF>::oop_store_at(p, offset, x);
} UNSAFE_END
UNSAFE_ENTRY(jobject, Unsafe_GetObjectVolatile(JNIEnv *env, jobject unsafe, jobject obj, jlong offset)) {
oop p = JNIHandles::resolve(obj);
- void* addr = index_oop_from_field_offset_long(p, offset);
-
- volatile oop v;
-
- if (support_IRIW_for_not_multiple_copy_atomic_cpu) {
- OrderAccess::fence();
- }
-
- if (UseCompressedOops) {
- volatile narrowOop n = *(volatile narrowOop*) addr;
- (void)const_cast<oop&>(v = oopDesc::decode_heap_oop(n));
- } else {
- (void)const_cast<oop&>(v = *(volatile oop*) addr);
- }
-
- ensure_satb_referent_alive(p, offset, v);
-
- OrderAccess::acquire();
+ assert_field_offset_sane(p, offset);
+ oop v = HeapAccess<MO_SEQ_CST | ON_UNKNOWN_OOP_REF>::oop_load_at(p, offset);
return JNIHandles::make_local(env, v);
} UNSAFE_END
UNSAFE_ENTRY(void, Unsafe_PutObjectVolatile(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jobject x_h)) {
oop x = JNIHandles::resolve(x_h);
oop p = JNIHandles::resolve(obj);
- void* addr = index_oop_from_field_offset_long(p, offset);
- OrderAccess::release();
-
- if (UseCompressedOops) {
- oop_store((narrowOop*)addr, x);
- } else {
- oop_store((oop*)addr, x);
- }
-
- OrderAccess::fence();
+ assert_field_offset_sane(p, offset);
+ HeapAccess<MO_SEQ_CST | ON_UNKNOWN_OOP_REF>::oop_store_at(p, offset, x);
} UNSAFE_END
UNSAFE_ENTRY(jobject, Unsafe_GetUncompressedObject(JNIEnv *env, jobject unsafe, jlong addr)) {
oop v = *(oop*) (address) addr;
-
return JNIHandles::make_local(env, v);
} UNSAFE_END
-#ifndef SUPPORTS_NATIVE_CX8
-
-// VM_Version::supports_cx8() is a surrogate for 'supports atomic long memory ops'.
-//
-// On platforms which do not support atomic compare-and-swap of jlong (8 byte)
-// values we have to use a lock-based scheme to enforce atomicity. This has to be
-// applied to all Unsafe operations that set the value of a jlong field. Even so
-// the compareAndSetLong operation will not be atomic with respect to direct stores
-// to the field from Java code. It is important therefore that any Java code that
-// utilizes these Unsafe jlong operations does not perform direct stores. To permit
-// direct loads of the field from Java code we must also use Atomic::store within the
-// locked regions. And for good measure, in case there are direct stores, we also
-// employ Atomic::load within those regions. Note that the field in question must be
-// volatile and so must have atomic load/store accesses applied at the Java level.
-//
-// The locking scheme could utilize a range of strategies for controlling the locking
-// granularity: from a lock per-field through to a single global lock. The latter is
-// the simplest and is used for the current implementation. Note that the Java object
-// that contains the field, can not, in general, be used for locking. To do so can lead
-// to deadlocks as we may introduce locking into what appears to the Java code to be a
-// lock-free path.
-//
-// As all the locked-regions are very short and themselves non-blocking we can treat
-// them as leaf routines and elide safepoint checks (ie we don't perform any thread
-// state transitions even when blocking for the lock). Note that if we do choose to
-// add safepoint checks and thread state transitions, we must ensure that we calculate
-// the address of the field _after_ we have acquired the lock, else the object may have
-// been moved by the GC
-
-UNSAFE_ENTRY(jlong, Unsafe_GetLongVolatile(JNIEnv *env, jobject unsafe, jobject obj, jlong offset)) {
- if (VM_Version::supports_cx8()) {
- return MemoryAccess(thread, obj, offset).get_volatile<jlong>();
- } else {
- return MemoryAccess(thread, obj, offset).get_jlong_locked();
- }
-} UNSAFE_END
-
-UNSAFE_ENTRY(void, Unsafe_PutLongVolatile(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jlong x)) {
- if (VM_Version::supports_cx8()) {
- MemoryAccess(thread, obj, offset).put_volatile<jlong>(x);
- } else {
- MemoryAccess(thread, obj, offset).put_jlong_locked(x);
- }
-} UNSAFE_END
-
-#endif // not SUPPORTS_NATIVE_CX8
-
UNSAFE_LEAF(jboolean, Unsafe_isBigEndian0(JNIEnv *env, jobject unsafe)) {
#ifdef VM_LITTLE_ENDIAN
return false;
@@ -472,13 +331,10 @@
DEFINE_GETSETOOP_VOLATILE(jshort, Short);
DEFINE_GETSETOOP_VOLATILE(jchar, Char);
DEFINE_GETSETOOP_VOLATILE(jint, Int);
+DEFINE_GETSETOOP_VOLATILE(jlong, Long);
DEFINE_GETSETOOP_VOLATILE(jfloat, Float);
DEFINE_GETSETOOP_VOLATILE(jdouble, Double);
-#ifdef SUPPORTS_NATIVE_CX8
-DEFINE_GETSETOOP_VOLATILE(jlong, Long);
-#endif
-
#undef DEFINE_GETSETOOP_VOLATILE
UNSAFE_LEAF(void, Unsafe_LoadFence(JNIEnv *env, jobject unsafe)) {
@@ -1001,85 +857,62 @@
oop x = JNIHandles::resolve(x_h);
oop e = JNIHandles::resolve(e_h);
oop p = JNIHandles::resolve(obj);
- HeapWord* addr = (HeapWord *)index_oop_from_field_offset_long(p, offset);
- oop res = oopDesc::atomic_compare_exchange_oop(x, addr, e, true);
- if (res == e) {
- update_barrier_set((void*)addr, x);
- }
+ assert_field_offset_sane(p, offset);
+ oop res = HeapAccess<ON_UNKNOWN_OOP_REF>::oop_atomic_cmpxchg_at(x, p, (ptrdiff_t)offset, e);
return JNIHandles::make_local(env, res);
} UNSAFE_END
UNSAFE_ENTRY(jint, Unsafe_CompareAndExchangeInt(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jint e, jint x)) {
oop p = JNIHandles::resolve(obj);
- jint* addr = (jint *) index_oop_from_field_offset_long(p, offset);
-
- return (jint)(Atomic::cmpxchg(x, addr, e));
+ if (oopDesc::is_null(p)) {
+ volatile jint* addr = (volatile jint*)index_oop_from_field_offset_long(p, offset);
+ return RawAccess<>::atomic_cmpxchg(x, addr, e);
+ } else {
+ assert_field_offset_sane(p, offset);
+ return HeapAccess<>::atomic_cmpxchg_at(x, p, (ptrdiff_t)offset, e);
+ }
} UNSAFE_END
UNSAFE_ENTRY(jlong, Unsafe_CompareAndExchangeLong(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jlong e, jlong x)) {
- Handle p(THREAD, JNIHandles::resolve(obj));
- jlong* addr = (jlong*)index_oop_from_field_offset_long(p(), offset);
-
-#ifdef SUPPORTS_NATIVE_CX8
- return (jlong)(Atomic::cmpxchg(x, addr, e));
-#else
- if (VM_Version::supports_cx8()) {
- return (jlong)(Atomic::cmpxchg(x, addr, e));
+ oop p = JNIHandles::resolve(obj);
+ if (oopDesc::is_null(p)) {
+ volatile jlong* addr = (volatile jlong*)index_oop_from_field_offset_long(p, offset);
+ return RawAccess<>::atomic_cmpxchg(x, addr, e);
} else {
- MutexLockerEx mu(UnsafeJlong_lock, Mutex::_no_safepoint_check_flag);
-
- jlong val = Atomic::load(addr);
- if (val == e) {
- Atomic::store(x, addr);
- }
- return val;
+ assert_field_offset_sane(p, offset);
+ return HeapAccess<>::atomic_cmpxchg_at(x, p, (ptrdiff_t)offset, e);
}
-#endif
} UNSAFE_END
UNSAFE_ENTRY(jboolean, Unsafe_CompareAndSetObject(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jobject e_h, jobject x_h)) {
oop x = JNIHandles::resolve(x_h);
oop e = JNIHandles::resolve(e_h);
oop p = JNIHandles::resolve(obj);
- HeapWord* addr = (HeapWord *)index_oop_from_field_offset_long(p, offset);
- oop res = oopDesc::atomic_compare_exchange_oop(x, addr, e, true);
- if (res != e) {
- return false;
- }
-
- update_barrier_set((void*)addr, x);
-
- return true;
+ assert_field_offset_sane(p, offset);
+ oop ret = HeapAccess<ON_UNKNOWN_OOP_REF>::oop_atomic_cmpxchg_at(x, p, (ptrdiff_t)offset, e);
+ return ret == e;
} UNSAFE_END
UNSAFE_ENTRY(jboolean, Unsafe_CompareAndSetInt(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jint e, jint x)) {
oop p = JNIHandles::resolve(obj);
- jint* addr = (jint *)index_oop_from_field_offset_long(p, offset);
-
- return (jint)(Atomic::cmpxchg(x, addr, e)) == e;
+ if (oopDesc::is_null(p)) {
+ volatile jint* addr = (volatile jint*)index_oop_from_field_offset_long(p, offset);
+ return RawAccess<>::atomic_cmpxchg(x, addr, e) == e;
+ } else {
+ assert_field_offset_sane(p, offset);
+ return HeapAccess<>::atomic_cmpxchg_at(x, p, (ptrdiff_t)offset, e) == e;
+ }
} UNSAFE_END
UNSAFE_ENTRY(jboolean, Unsafe_CompareAndSetLong(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jlong e, jlong x)) {
- Handle p(THREAD, JNIHandles::resolve(obj));
- jlong* addr = (jlong*)index_oop_from_field_offset_long(p(), offset);
-
-#ifdef SUPPORTS_NATIVE_CX8
- return (jlong)(Atomic::cmpxchg(x, addr, e)) == e;
-#else
- if (VM_Version::supports_cx8()) {
- return (jlong)(Atomic::cmpxchg(x, addr, e)) == e;
+ oop p = JNIHandles::resolve(obj);
+ if (oopDesc::is_null(p)) {
+ volatile jlong* addr = (volatile jlong*)index_oop_from_field_offset_long(p, offset);
+ return RawAccess<>::atomic_cmpxchg(x, addr, e) == e;
} else {
- MutexLockerEx mu(UnsafeJlong_lock, Mutex::_no_safepoint_check_flag);
-
- jlong val = Atomic::load(addr);
- if (val != e) {
- return false;
- }
-
- Atomic::store(x, addr);
- return true;
+ assert_field_offset_sane(p, offset);
+ return HeapAccess<>::atomic_cmpxchg_at(x, p, (ptrdiff_t)offset, e) == e;
}
-#endif
} UNSAFE_END
UNSAFE_ENTRY(void, Unsafe_Park(JNIEnv *env, jobject unsafe, jboolean isAbsolute, jlong time)) {