1 // Copyright 2020 the V8 project authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4
5 #ifndef V8_SANDBOX_EXTERNAL_POINTER_INL_H_
6 #define V8_SANDBOX_EXTERNAL_POINTER_INL_H_
7
8 #include "include/v8-internal.h"
9 #include "src/execution/isolate.h"
10 #include "src/sandbox/external-pointer-table-inl.h"
11 #include "src/sandbox/external-pointer.h"
12
13 namespace v8 {
14 namespace internal {
15
DecodeExternalPointer(const Isolate * isolate,ExternalPointer_t encoded_pointer,ExternalPointerTag tag)16 V8_INLINE Address DecodeExternalPointer(const Isolate* isolate,
17 ExternalPointer_t encoded_pointer,
18 ExternalPointerTag tag) {
19 #ifdef V8_SANDBOXED_EXTERNAL_POINTERS
20 STATIC_ASSERT(kExternalPointerSize == kInt32Size);
21 uint32_t index = encoded_pointer >> kExternalPointerIndexShift;
22 return isolate->external_pointer_table().Get(index, tag);
23 #else
24 STATIC_ASSERT(kExternalPointerSize == kSystemPointerSize);
25 return encoded_pointer;
26 #endif
27 }
28
InitExternalPointerField(Address field_address,Isolate * isolate,ExternalPointerTag tag)29 V8_INLINE void InitExternalPointerField(Address field_address, Isolate* isolate,
30 ExternalPointerTag tag) {
31 InitExternalPointerField(field_address, isolate, kNullExternalPointer, tag);
32 }
33
InitExternalPointerField(Address field_address,Isolate * isolate,Address value,ExternalPointerTag tag)34 V8_INLINE void InitExternalPointerField(Address field_address, Isolate* isolate,
35 Address value, ExternalPointerTag tag) {
36 #ifdef V8_SANDBOXED_EXTERNAL_POINTERS
37 ExternalPointer_t index = isolate->external_pointer_table().Allocate();
38 isolate->external_pointer_table().Set(index, value, tag);
39 index <<= kExternalPointerIndexShift;
40 base::Memory<ExternalPointer_t>(field_address) = index;
41 #else
42 // Pointer compression causes types larger than kTaggedSize to be unaligned.
43 constexpr bool v8_pointer_compression_unaligned =
44 kExternalPointerSize > kTaggedSize;
45 ExternalPointer_t encoded_value = static_cast<ExternalPointer_t>(value);
46 if (v8_pointer_compression_unaligned) {
47 base::WriteUnalignedValue<ExternalPointer_t>(field_address, encoded_value);
48 } else {
49 base::Memory<ExternalPointer_t>(field_address) = encoded_value;
50 }
51 #endif // V8_SANDBOXED_EXTERNAL_POINTERS
52 }
53
ReadRawExternalPointerField(Address field_address)54 V8_INLINE ExternalPointer_t ReadRawExternalPointerField(Address field_address) {
55 // Pointer compression causes types larger than kTaggedSize to be unaligned.
56 constexpr bool v8_pointer_compression_unaligned =
57 kExternalPointerSize > kTaggedSize;
58 if (v8_pointer_compression_unaligned) {
59 return base::ReadUnalignedValue<ExternalPointer_t>(field_address);
60 } else {
61 return base::Memory<ExternalPointer_t>(field_address);
62 }
63 }
64
ReadExternalPointerField(Address field_address,const Isolate * isolate,ExternalPointerTag tag)65 V8_INLINE Address ReadExternalPointerField(Address field_address,
66 const Isolate* isolate,
67 ExternalPointerTag tag) {
68 ExternalPointer_t encoded_value = ReadRawExternalPointerField(field_address);
69 return DecodeExternalPointer(isolate, encoded_value, tag);
70 }
71
WriteExternalPointerField(Address field_address,Isolate * isolate,Address value,ExternalPointerTag tag)72 V8_INLINE void WriteExternalPointerField(Address field_address,
73 Isolate* isolate, Address value,
74 ExternalPointerTag tag) {
75 #ifdef V8_SANDBOXED_EXTERNAL_POINTERS
76 ExternalPointer_t index = base::Memory<ExternalPointer_t>(field_address);
77 index >>= kExternalPointerIndexShift;
78 isolate->external_pointer_table().Set(index, value, tag);
79 #else
80 // Pointer compression causes types larger than kTaggedSize to be unaligned.
81 constexpr bool v8_pointer_compression_unaligned =
82 kExternalPointerSize > kTaggedSize;
83 ExternalPointer_t encoded_value = static_cast<ExternalPointer_t>(value);
84 if (v8_pointer_compression_unaligned) {
85 base::WriteUnalignedValue<ExternalPointer_t>(field_address, encoded_value);
86 } else {
87 base::Memory<ExternalPointer_t>(field_address) = encoded_value;
88 }
89 #endif // V8_SANDBOXED_EXTERNAL_POINTERS
90 }
91
92 } // namespace internal
93 } // namespace v8
94
95 #endif // V8_SANDBOX_EXTERNAL_POINTER_INL_H_
96