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[js] Try to catch bad pointers for GC and bail if not valid.

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Moonchild 2020-08-03 09:41:42 +00:00 • committed by Roy Tam
commit b52bc1586d
2 changed files with 42 additions and 0 deletions
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37
js/public/HeapAPI.h
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@ -51,6 +51,7 @@ const size_t ChunkMarkBitmapBits = 129024;
const size_t ChunkRuntimeOffset = ChunkSize - sizeof(void*);
const size_t ChunkTrailerSize = 2 * sizeof(uintptr_t) + sizeof(uint64_t);
const size_t ChunkLocationOffset = ChunkSize - ChunkTrailerSize;
const size_t ChunkStoreBufferOffset = ChunkSize - ChunkTrailerSize + sizeof(uint64_t);
const size_t ArenaZoneOffset = sizeof(size_t);
const size_t ArenaHeaderSize = sizeof(size_t) + 2 * sizeof(uintptr_t) +
sizeof(size_t) + sizeof(uintptr_t);
@ -326,6 +327,20 @@ CellIsMarkedGray(const Cell* cell)
extern JS_PUBLIC_API(bool)
CellIsMarkedGrayIfKnown(const Cell* cell);
MOZ_ALWAYS_INLINE ChunkLocation GetCellLocation(const void* cell) {
uintptr_t addr = uintptr_t(cell);
addr &= ~js::gc::ChunkMask;
addr |= js::gc::ChunkLocationOffset;
return *reinterpret_cast<ChunkLocation*>(addr);
}
MOZ_ALWAYS_INLINE bool NurseryCellHasStoreBuffer(const void* cell) {
uintptr_t addr = uintptr_t(cell);
addr &= ~js::gc::ChunkMask;
addr |= js::gc::ChunkStoreBufferOffset;
return *reinterpret_cast<void**>(addr) != nullptr;
}
} /* namespace detail */
MOZ_ALWAYS_INLINE bool
@ -341,6 +356,28 @@ IsInsideNursery(const js::gc::Cell* cell)
return location == ChunkLocation::Nursery;
}
MOZ_ALWAYS_INLINE bool IsCellPointerValid(const void* cell) {
auto addr = uintptr_t(cell);
if (addr < ChunkSize || addr % CellSize != 0) {
return false;
}
auto location = detail::GetCellLocation(cell);
if (location == ChunkLocation::TenuredHeap) {
return !!detail::GetGCThingZone(addr);
}
if (location == ChunkLocation::Nursery) {
return detail::NurseryCellHasStoreBuffer(cell);
}
return false;
}
MOZ_ALWAYS_INLINE bool IsCellPointerValidOrNull(const void* cell) {
if (!cell) {
return true;
}
return IsCellPointerValid(cell);
}
} /* namespace gc */
} /* namespace js */