Adding upstream version 86.0.1.upstream/86.0.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 476 insertions, 0 deletions

diff --git a/js/src/vm/SharedArrayObject.cpp b/js/src/vm/SharedArrayObject.cpp
new file mode 100644
index 0000000000..2a38b77380
--- /dev/null
+++ b/js/src/vm/SharedArrayObject.cpp
@@ -0,0 +1,476 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * vim: set ts=8 sts=2 et sw=2 tw=80:
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "vm/SharedArrayObject.h"
+
+#include "mozilla/Atomics.h"
+#include "mozilla/CheckedInt.h"
+
+#include "jsfriendapi.h"
+
+#include "gc/FreeOp.h"
+#include "jit/AtomicOperations.h"
+#include "js/friend/ErrorMessages.h"  // js::GetErrorMessage, JSMSG_*
+#include "js/PropertySpec.h"
+#include "js/SharedArrayBuffer.h"
+#include "js/Wrapper.h"
+#include "util/Memory.h"
+#include "vm/SharedMem.h"
+#include "wasm/WasmSignalHandlers.h"
+#include "wasm/WasmTypes.h"
+
+#include "vm/JSObject-inl.h"
+#include "vm/NativeObject-inl.h"
+
+using mozilla::CheckedInt;
+using mozilla::Maybe;
+using mozilla::Nothing;
+
+using namespace js;
+
+static size_t SharedArrayAccessibleSize(size_t length) {
+  return AlignBytes(length, gc::SystemPageSize());
+}
+
+// The mapped size for a plain shared array buffer, used only for tracking
+// memory usage. This is incorrect for some WASM cases, and for hypothetical
+// callers of js::SharedArrayBufferObject::createFromNewRawBuffer that do not
+// currently exist, but it's fine as a signal of GC pressure.
+static size_t SharedArrayMappedSize(size_t length) {
+  return SharedArrayAccessibleSize(length) + gc::SystemPageSize();
+}
+
+// `maxSize` must be something for wasm, nothing for other cases.
+SharedArrayRawBuffer* SharedArrayRawBuffer::Allocate(
+    BufferSize length, const Maybe<uint64_t>& maxSize,
+    const Maybe<size_t>& mappedSize) {
+  MOZ_RELEASE_ASSERT(length.get() <= ArrayBufferObject::maxBufferByteLength());
+
+  size_t accessibleSize = SharedArrayAccessibleSize(length.get());
+  if (accessibleSize < length.get()) {
+    return nullptr;
+  }
+
+  bool preparedForWasm = maxSize.isSome();
+  uint64_t computedMaxSize;
+  size_t computedMappedSize;
+
+  if (preparedForWasm) {
+    computedMaxSize = *maxSize;
+    computedMappedSize = mappedSize.isSome()
+                             ? *mappedSize
+                             : wasm::ComputeMappedSize(computedMaxSize);
+  } else {
+    computedMappedSize = accessibleSize;
+    computedMaxSize = accessibleSize;
+  }
+
+  MOZ_ASSERT(accessibleSize <= computedMaxSize);
+  MOZ_ASSERT(accessibleSize <= computedMappedSize);
+
+  uint64_t mappedSizeWithHeader = computedMappedSize + gc::SystemPageSize();
+  uint64_t accessibleSizeWithHeader = accessibleSize + gc::SystemPageSize();
+
+  void* p = MapBufferMemory(mappedSizeWithHeader, accessibleSizeWithHeader);
+  if (!p) {
+    return nullptr;
+  }
+
+  uint8_t* buffer = reinterpret_cast<uint8_t*>(p) + gc::SystemPageSize();
+  uint8_t* base = buffer - sizeof(SharedArrayRawBuffer);
+  SharedArrayRawBuffer* rawbuf = new (base) SharedArrayRawBuffer(
+      buffer, length, computedMaxSize, computedMappedSize, preparedForWasm);
+  MOZ_ASSERT(rawbuf->length_ == length.get());  // Deallocation needs this
+  return rawbuf;
+}
+
+void SharedArrayRawBuffer::tryGrowMaxSizeInPlace(uint64_t deltaMaxSize) {
+  CheckedInt<uint64_t> newMaxSize = maxSize_;
+  newMaxSize += deltaMaxSize;
+  MOZ_ASSERT(newMaxSize.isValid());
+  MOZ_ASSERT(newMaxSize.value() % wasm::PageSize == 0);
+
+  size_t newMappedSize = wasm::ComputeMappedSize(newMaxSize.value());
+  MOZ_ASSERT(mappedSize_ <= newMappedSize);
+  if (mappedSize_ == newMappedSize) {
+    return;
+  }
+
+  if (!ExtendBufferMapping(basePointer(), mappedSize_, newMappedSize)) {
+    return;
+  }
+
+  mappedSize_ = newMappedSize;
+  maxSize_ = newMaxSize.value();
+}
+
+bool SharedArrayRawBuffer::wasmGrowToSizeInPlace(const Lock&,
+                                                 BufferSize newLength) {
+  // Note, caller must guard on the limit appropriate to the memory type
+  if (newLength.get() > ArrayBufferObject::maxBufferByteLength()) {
+    return false;
+  }
+
+  MOZ_ASSERT(newLength.get() >= length_);
+
+  if (newLength.get() == length_) {
+    return true;
+  }
+
+  size_t delta = newLength.get() - length_;
+  MOZ_ASSERT(delta % wasm::PageSize == 0);
+
+  uint8_t* dataEnd = dataPointerShared().unwrap(/* for resize */) + length_;
+  MOZ_ASSERT(uintptr_t(dataEnd) % gc::SystemPageSize() == 0);
+
+  if (!CommitBufferMemory(dataEnd, delta)) {
+    return false;
+  }
+
+  // We rely on CommitBufferMemory (and therefore memmap/VirtualAlloc) to only
+  // return once it has committed memory for all threads. We only update with a
+  // new length once this has occurred.
+  length_ = newLength.get();
+
+  return true;
+}
+
+bool SharedArrayRawBuffer::addReference() {
+  MOZ_RELEASE_ASSERT(refcount_ > 0);
+
+  // Be careful never to overflow the refcount field.
+  for (;;) {
+    uint32_t old_refcount = refcount_;
+    uint32_t new_refcount = old_refcount + 1;
+    if (new_refcount == 0) {
+      return false;
+    }
+    if (refcount_.compareExchange(old_refcount, new_refcount)) {
+      return true;
+    }
+  }
+}
+
+void SharedArrayRawBuffer::dropReference() {
+  // Normally if the refcount is zero then the memory will have been unmapped
+  // and this test may just crash, but if the memory has been retained for any
+  // reason we will catch the underflow here.
+  MOZ_RELEASE_ASSERT(refcount_ > 0);
+
+  // Drop the reference to the buffer.
+  uint32_t new_refcount = --refcount_;  // Atomic.
+  if (new_refcount) {
+    return;
+  }
+
+  size_t mappedSizeWithHeader = mappedSize_ + gc::SystemPageSize();
+
+  // This was the final reference, so release the buffer.
+  UnmapBufferMemory(basePointer(), mappedSizeWithHeader);
+}
+
+MOZ_ALWAYS_INLINE bool SharedArrayBufferObject::byteLengthGetterImpl(
+    JSContext* cx, const CallArgs& args) {
+  MOZ_ASSERT(IsSharedArrayBuffer(args.thisv()));
+  auto* buffer = &args.thisv().toObject().as<SharedArrayBufferObject>();
+  args.rval().setNumber(buffer->byteLength().get());
+  return true;
+}
+
+bool SharedArrayBufferObject::byteLengthGetter(JSContext* cx, unsigned argc,
+                                               Value* vp) {
+  CallArgs args = CallArgsFromVp(argc, vp);
+  return CallNonGenericMethod<IsSharedArrayBuffer, byteLengthGetterImpl>(cx,
+                                                                         args);
+}
+
+// ES2017 draft rev 6390c2f1b34b309895d31d8c0512eac8660a0210
+// 24.2.2.1 SharedArrayBuffer( length )
+bool SharedArrayBufferObject::class_constructor(JSContext* cx, unsigned argc,
+                                                Value* vp) {
+  CallArgs args = CallArgsFromVp(argc, vp);
+
+  // Step 1.
+  if (!ThrowIfNotConstructing(cx, args, "SharedArrayBuffer")) {
+    return false;
+  }
+
+  // Step 2.
+  uint64_t byteLength;
+  if (!ToIndex(cx, args.get(0), &byteLength)) {
+    return false;
+  }
+
+  // Step 3 (Inlined 24.2.1.1 AllocateSharedArrayBuffer).
+  // 24.2.1.1, step 1 (Inlined 9.1.14 OrdinaryCreateFromConstructor).
+  RootedObject proto(cx);
+  if (!GetPrototypeFromBuiltinConstructor(cx, args, JSProto_SharedArrayBuffer,
+                                          &proto)) {
+    return false;
+  }
+
+  // 24.2.1.1, step 3 (Inlined 6.2.7.2 CreateSharedByteDataBlock, step 2).
+  // Refuse to allocate too large buffers.
+  if (byteLength > ArrayBufferObject::maxBufferByteLength()) {
+    JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr,
+                              JSMSG_SHARED_ARRAY_BAD_LENGTH);
+    return false;
+  }
+
+  // 24.2.1.1, steps 1 and 4-6.
+  JSObject* bufobj = New(cx, BufferSize(byteLength), proto);
+  if (!bufobj) {
+    return false;
+  }
+  args.rval().setObject(*bufobj);
+  return true;
+}
+
+SharedArrayBufferObject* SharedArrayBufferObject::New(JSContext* cx,
+                                                      BufferSize length,
+                                                      HandleObject proto) {
+  SharedArrayRawBuffer* buffer =
+      SharedArrayRawBuffer::Allocate(length, Nothing(), Nothing());
+  if (!buffer) {
+    js::ReportOutOfMemory(cx);
+    return nullptr;
+  }
+
+  SharedArrayBufferObject* obj = New(cx, buffer, length, proto);
+  if (!obj) {
+    buffer->dropReference();
+    return nullptr;
+  }
+
+  return obj;
+}
+
+SharedArrayBufferObject* SharedArrayBufferObject::New(
+    JSContext* cx, SharedArrayRawBuffer* buffer, BufferSize length,
+    HandleObject proto) {
+  MOZ_ASSERT(cx->realm()->creationOptions().getSharedMemoryAndAtomicsEnabled());
+
+  AutoSetNewObjectMetadata metadata(cx);
+  Rooted<SharedArrayBufferObject*> obj(
+      cx, NewObjectWithClassProto<SharedArrayBufferObject>(cx, proto));
+  if (!obj) {
+    return nullptr;
+  }
+
+  MOZ_ASSERT(obj->getClass() == &class_);
+
+  cx->runtime()->incSABCount();
+
+  if (!obj->acceptRawBuffer(buffer, length)) {
+    js::ReportOutOfMemory(cx);
+    return nullptr;
+  }
+
+  return obj;
+}
+
+bool SharedArrayBufferObject::acceptRawBuffer(SharedArrayRawBuffer* buffer,
+                                              BufferSize length) {
+  if (!zone()->addSharedMemory(buffer, SharedArrayMappedSize(length.get()),
+                               MemoryUse::SharedArrayRawBuffer)) {
+    return false;
+  }
+
+  setReservedSlot(RAWBUF_SLOT, PrivateValue(buffer));
+  setReservedSlot(LENGTH_SLOT, PrivateValue(length.get()));
+  return true;
+}
+
+void SharedArrayBufferObject::dropRawBuffer() {
+  size_t size = SharedArrayMappedSize(byteLength().get());
+  zoneFromAnyThread()->removeSharedMemory(rawBufferObject(), size,
+                                          MemoryUse::SharedArrayRawBuffer);
+  setReservedSlot(RAWBUF_SLOT, UndefinedValue());
+}
+
+SharedArrayRawBuffer* SharedArrayBufferObject::rawBufferObject() const {
+  Value v = getReservedSlot(RAWBUF_SLOT);
+  MOZ_ASSERT(!v.isUndefined());
+  return reinterpret_cast<SharedArrayRawBuffer*>(v.toPrivate());
+}
+
+void SharedArrayBufferObject::Finalize(JSFreeOp* fop, JSObject* obj) {
+  // Must be foreground finalizable so that we can account for the object.
+  MOZ_ASSERT(fop->onMainThread());
+  fop->runtime()->decSABCount();
+
+  SharedArrayBufferObject& buf = obj->as<SharedArrayBufferObject>();
+
+  // Detect the case of failure during SharedArrayBufferObject creation,
+  // which causes a SharedArrayRawBuffer to never be attached.
+  Value v = buf.getReservedSlot(RAWBUF_SLOT);
+  if (!v.isUndefined()) {
+    buf.rawBufferObject()->dropReference();
+    buf.dropRawBuffer();
+  }
+}
+
+/* static */
+void SharedArrayBufferObject::addSizeOfExcludingThis(
+    JSObject* obj, mozilla::MallocSizeOf mallocSizeOf, JS::ClassInfo* info) {
+  // Divide the buffer size by the refcount to get the fraction of the buffer
+  // owned by this thread. It's conceivable that the refcount might change in
+  // the middle of memory reporting, in which case the amount reported for
+  // some threads might be to high (if the refcount goes up) or too low (if
+  // the refcount goes down). But that's unlikely and hard to avoid, so we
+  // just live with the risk.
+  const SharedArrayBufferObject& buf = obj->as<SharedArrayBufferObject>();
+  info->objectsNonHeapElementsShared +=
+      buf.byteLength().get() / buf.rawBufferObject()->refcount();
+}
+
+/* static */
+void SharedArrayBufferObject::copyData(
+    Handle<SharedArrayBufferObject*> toBuffer, size_t toIndex,
+    Handle<SharedArrayBufferObject*> fromBuffer, size_t fromIndex,
+    size_t count) {
+  MOZ_ASSERT(toBuffer->byteLength().get() >= count);
+  MOZ_ASSERT(toBuffer->byteLength().get() >= toIndex + count);
+  MOZ_ASSERT(fromBuffer->byteLength().get() >= fromIndex);
+  MOZ_ASSERT(fromBuffer->byteLength().get() >= fromIndex + count);
+
+  jit::AtomicOperations::memcpySafeWhenRacy(
+      toBuffer->dataPointerShared() + toIndex,
+      fromBuffer->dataPointerShared() + fromIndex, count);
+}
+
+SharedArrayBufferObject* SharedArrayBufferObject::createFromNewRawBuffer(
+    JSContext* cx, SharedArrayRawBuffer* buffer, BufferSize initialSize) {
+  MOZ_ASSERT(cx->realm()->creationOptions().getSharedMemoryAndAtomicsEnabled());
+
+  AutoSetNewObjectMetadata metadata(cx);
+  SharedArrayBufferObject* obj =
+      NewBuiltinClassInstance<SharedArrayBufferObject>(cx);
+  if (!obj) {
+    buffer->dropReference();
+    return nullptr;
+  }
+
+  cx->runtime()->incSABCount();
+
+  if (!obj->acceptRawBuffer(buffer, initialSize)) {
+    buffer->dropReference();
+    return nullptr;
+  }
+
+  return obj;
+}
+
+static const JSClassOps SharedArrayBufferObjectClassOps = {
+    nullptr,                            // addProperty
+    nullptr,                            // delProperty
+    nullptr,                            // enumerate
+    nullptr,                            // newEnumerate
+    nullptr,                            // resolve
+    nullptr,                            // mayResolve
+    SharedArrayBufferObject::Finalize,  // finalize
+    nullptr,                            // call
+    nullptr,                            // hasInstance
+    nullptr,                            // construct
+    nullptr,                            // trace
+};
+
+static const JSFunctionSpec sharedarrray_functions[] = {JS_FS_END};
+
+static const JSPropertySpec sharedarrray_properties[] = {
+    JS_SELF_HOSTED_SYM_GET(species, "$SharedArrayBufferSpecies", 0), JS_PS_END};
+
+static const JSFunctionSpec sharedarray_proto_functions[] = {
+    JS_SELF_HOSTED_FN("slice", "SharedArrayBufferSlice", 2, 0), JS_FS_END};
+
+static const JSPropertySpec sharedarray_proto_properties[] = {
+    JS_PSG("byteLength", SharedArrayBufferObject::byteLengthGetter, 0),
+    JS_STRING_SYM_PS(toStringTag, "SharedArrayBuffer", JSPROP_READONLY),
+    JS_PS_END};
+
+static const ClassSpec SharedArrayBufferObjectClassSpec = {
+    GenericCreateConstructor<SharedArrayBufferObject::class_constructor, 1,
+                             gc::AllocKind::FUNCTION>,
+    GenericCreatePrototype<SharedArrayBufferObject>,
+    sharedarrray_functions,
+    sharedarrray_properties,
+    sharedarray_proto_functions,
+    sharedarray_proto_properties};
+
+const JSClass SharedArrayBufferObject::class_ = {
+    "SharedArrayBuffer",
+    JSCLASS_DELAY_METADATA_BUILDER |
+        JSCLASS_HAS_RESERVED_SLOTS(SharedArrayBufferObject::RESERVED_SLOTS) |
+        JSCLASS_HAS_CACHED_PROTO(JSProto_SharedArrayBuffer) |
+        JSCLASS_FOREGROUND_FINALIZE,
+    &SharedArrayBufferObjectClassOps, &SharedArrayBufferObjectClassSpec,
+    JS_NULL_CLASS_EXT};
+
+const JSClass SharedArrayBufferObject::protoClass_ = {
+    "SharedArrayBuffer.prototype",
+    JSCLASS_HAS_CACHED_PROTO(JSProto_SharedArrayBuffer), JS_NULL_CLASS_OPS,
+    &SharedArrayBufferObjectClassSpec};
+
+bool js::IsSharedArrayBuffer(HandleValue v) {
+  return v.isObject() && v.toObject().is<SharedArrayBufferObject>();
+}
+
+bool js::IsSharedArrayBuffer(HandleObject o) {
+  return o->is<SharedArrayBufferObject>();
+}
+
+bool js::IsSharedArrayBuffer(JSObject* o) {
+  return o->is<SharedArrayBufferObject>();
+}
+
+SharedArrayBufferObject& js::AsSharedArrayBuffer(HandleObject obj) {
+  MOZ_ASSERT(IsSharedArrayBuffer(obj));
+  return obj->as<SharedArrayBufferObject>();
+}
+
+JS_FRIEND_API uint32_t JS::GetSharedArrayBufferByteLength(JSObject* obj) {
+  auto* aobj = obj->maybeUnwrapAs<SharedArrayBufferObject>();
+  return aobj ? aobj->byteLength().deprecatedGetUint32() : 0;
+}
+
+JS_FRIEND_API void JS::GetSharedArrayBufferLengthAndData(JSObject* obj,
+                                                         uint32_t* length,
+                                                         bool* isSharedMemory,
+                                                         uint8_t** data) {
+  MOZ_ASSERT(obj->is<SharedArrayBufferObject>());
+  *length =
+      obj->as<SharedArrayBufferObject>().byteLength().deprecatedGetUint32();
+  *data = obj->as<SharedArrayBufferObject>().dataPointerShared().unwrap(
+      /*safe - caller knows*/);
+  *isSharedMemory = true;
+}
+
+JS_FRIEND_API JSObject* JS::NewSharedArrayBuffer(JSContext* cx,
+                                                 uint32_t nbytes) {
+  MOZ_ASSERT(cx->realm()->creationOptions().getSharedMemoryAndAtomicsEnabled());
+
+  MOZ_ASSERT(nbytes <= INT32_MAX);
+  return SharedArrayBufferObject::New(cx, BufferSize(nbytes),
+                                      /* proto = */ nullptr);
+}
+
+JS_FRIEND_API bool JS::IsSharedArrayBufferObject(JSObject* obj) {
+  return obj->canUnwrapAs<SharedArrayBufferObject>();
+}
+
+JS_FRIEND_API uint8_t* JS::GetSharedArrayBufferData(
+    JSObject* obj, bool* isSharedMemory, const JS::AutoRequireNoGC&) {
+  auto* aobj = obj->maybeUnwrapAs<SharedArrayBufferObject>();
+  if (!aobj) {
+    return nullptr;
+  }
+  *isSharedMemory = true;
+  return aobj->dataPointerShared().unwrap(/*safe - caller knows*/);
+}
+
+JS_PUBLIC_API bool JS::ContainsSharedArrayBuffer(JSContext* cx) {
+  return cx->runtime()->hasLiveSABs();
+}