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[sandbox] Split ExternalPointerTag definitions for shared/non-shared

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- Change definition to macro-style to be able to assert that masks/tags
  are correct.
- Split definition of shared/non-shared tags.
- Use bit 62 (for now) to indicate tags are shared.

Bug: v8:10391
Change-Id: Ia3ad6294cf5e6fd0c4dc2a328f976f295da762f5
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3726009
Reviewed-by: Samuel Groß <saelo@chromium.org>
Commit-Queue: Patrick Thier <pthier@chromium.org>
Cr-Commit-Position: refs/heads/main@{#81400}
This commit is contained in:
Patrick Thier 2022-06-27 12:15:33 +00:00 committed by V8 LUCI CQ
parent fd8309e806
commit ece27af693
1 changed files with 50 additions and 24 deletions
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74
include/v8-internal.h
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@ -304,36 +304,62 @@ static_assert((1 << (32 - kExternalPointerIndexShift)) ==
constexpr uint64_t kExternalPointerTagMask = 0xffff000000000000;
constexpr uint64_t kExternalPointerTagShift = 48;
#define MAKE_TAG(v) (static_cast<uint64_t>(v) << kExternalPointerTagShift)
// clang-format off
enum ExternalPointerTag : uint64_t {
kExternalPointerNullTag = MAKE_TAG(0b0000000000000000),
kExternalPointerFreeEntryTag = MAKE_TAG(0b0111111100000000),
// Begin shared external object tags
// Update kSharedExternalObjectMask and kSharedExternalObjectTag when new
// tags are shared.
kWaiterQueueNodeTag = MAKE_TAG(0b1000000111111111),
kExternalStringResourceTag = MAKE_TAG(0b1000001011111111),
kExternalStringResourceDataTag = MAKE_TAG(0b1000001101111111),
// End shared external object tags
kForeignForeignAddressTag = MAKE_TAG(0b1000001110111111),
kNativeContextMicrotaskQueueTag = MAKE_TAG(0b1000001111011111),
kEmbedderDataSlotPayloadTag = MAKE_TAG(0b1000001111101111),
kCodeEntryPointTag = MAKE_TAG(0b1000001111110111),
kExternalObjectValueTag = MAKE_TAG(0b1000001111111011),
kCallHandlerInfoCallbackTag = MAKE_TAG(0b1000001111111101),
kCallHandlerInfoJsCallbackTag = MAKE_TAG(0b1000001111111110),
kAccessorInfoGetterTag = MAKE_TAG(0b1000010011111111),
kAccessorInfoJsGetterTag = MAKE_TAG(0b1000010101111111),
kAccessorInfoSetterTag = MAKE_TAG(0b1000010110111111),
};
// clang-format on
#define EXTERNAL_POINTER_TAGS(V) \
V(kExternalPointerNullTag, 0b0000000000000000) \
V(kExternalPointerFreeEntryTag, 0b0011111100000000) \
V(kForeignForeignAddressTag, 0b1000001110111111) \
V(kNativeContextMicrotaskQueueTag, 0b1000001111011111) \
V(kEmbedderDataSlotPayloadTag, 0b1000001111101111) \
V(kCodeEntryPointTag, 0b1000001111110111) \
V(kExternalObjectValueTag, 0b1000001111111011) \
V(kCallHandlerInfoCallbackTag, 0b1000001111111101) \
V(kCallHandlerInfoJsCallbackTag, 0b1000001111111110) \
V(kAccessorInfoGetterTag, 0b1000010011111111) \
V(kAccessorInfoJsGetterTag, 0b1000010101111111) \
V(kAccessorInfoSetterTag, 0b1000010110111111)
// Shared external pointers can be access from shared isolates. They are stored
// in a shared external pointer table.
constexpr uint64_t kSharedExternalObjectMask = MAKE_TAG(0b1111110001111111);
constexpr uint64_t kSharedExternalObjectTag = MAKE_TAG(0b1000000001111111);
// The second most significant bit indicates that a tag is shared. If we ever
// can't afford to reserve the bit to indicate shared tags, the only invariant
// is that kSharedExternalObjectMask and kSharedExternalObjectTag can
// distinguish shared from non-shared tags.
#define SHARED_EXTERNAL_POINTER_TAGS(V) \
V(kWaiterQueueNodeTag, 0b1100000111111111) \
V(kExternalStringResourceTag, 0b1100001011111111) \
V(kExternalStringResourceDataTag, 0b1100001101111111)
constexpr uint64_t kSharedExternalObjectMask = MAKE_TAG(0b1100000000000000);
constexpr uint64_t kSharedExternalObjectTag = MAKE_TAG(0b1100000000000000);
#define EXTERNAL_POINTER_TAG_ENUM(Name, Bits) Name = MAKE_TAG(Bits),
enum ExternalPointerTag : uint64_t {
EXTERNAL_POINTER_TAGS(EXTERNAL_POINTER_TAG_ENUM)
SHARED_EXTERNAL_POINTER_TAGS(EXTERNAL_POINTER_TAG_ENUM)
};
// clang-format on
#undef MAKE_TAG
#undef EXTERNAL_POINTER_TAG_ENUM
// Sanity checks.
#define CHECK_SHARED_EXTERNAL_POINTER_TAGS(Tag, ...) \
static_assert((Tag & kSharedExternalObjectMask) == kSharedExternalObjectTag);
#define CHECK_NON_SHARED_EXTERNAL_POINTER_TAGS(Tag, ...) \
static_assert((Tag & kSharedExternalObjectMask) != kSharedExternalObjectTag);
SHARED_EXTERNAL_POINTER_TAGS(CHECK_SHARED_EXTERNAL_POINTER_TAGS)
EXTERNAL_POINTER_TAGS(CHECK_NON_SHARED_EXTERNAL_POINTER_TAGS)
#undef CHECK_NON_SHARED_EXTERNAL_POINTER_TAGS
#undef CHECK_SHARED_EXTERNAL_POINTER_TAGS
#undef SHARED_EXTERNAL_POINTER_TAGS
#undef EXTERNAL_POINTER_TAGS
#ifdef V8_SANDBOXED_EXTERNAL_POINTERS
// True if the external resource can be accessed from shared isolates.