| // Copyright 2023 The Chromium Authors |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #ifndef BASE_ALLOCATOR_PARTITION_ALLOCATOR_SRC_PARTITION_ALLOC_PARTITION_PAGE_CONSTANTS_H_ |
| #define BASE_ALLOCATOR_PARTITION_ALLOCATOR_SRC_PARTITION_ALLOC_PARTITION_PAGE_CONSTANTS_H_ |
| |
| #include "build/build_config.h" |
| #include "partition_alloc/partition_alloc_base/compiler_specific.h" |
| #include "partition_alloc/partition_alloc_constants.h" |
| |
| namespace partition_alloc::internal { |
| |
| #if BUILDFLAG(HAS_64_BIT_POINTERS) && BUILDFLAG(IS_APPLE) |
| // System page size is not a constant on Apple OSes, but is either 4 or 16kiB |
| // (1 << 12 or 1 << 14), as checked in PartitionRoot::Init(). And |
| // PartitionPageSize() is 4 times the OS page size. |
| static constexpr size_t kMaxSlotsPerSlotSpan = 4 * (1 << 14) / kSmallestBucket; |
| #elif BUILDFLAG(IS_LINUX) && defined(ARCH_CPU_ARM64) |
| // System page size can be 4, 16, or 64 kiB on Linux on arm64. 64 kiB is |
| // currently (kMaxSlotsPerSlotSpanBits == 13) not supported by the code, |
| // so we use the 16 kiB maximum (64 kiB will crash). |
| static constexpr size_t kMaxSlotsPerSlotSpan = 4 * (1 << 14) / kSmallestBucket; |
| #else |
| // A slot span can "span" multiple PartitionPages, but then its slot size is |
| // larger, so it doesn't have as many slots. |
| static constexpr size_t kMaxSlotsPerSlotSpan = |
| PartitionPageSize() / kSmallestBucket; |
| #endif // BUILDFLAG(HAS_64_BIT_POINTERS) && BUILDFLAG(IS_APPLE) |
| |
| } // namespace partition_alloc::internal |
| |
| #endif // BASE_ALLOCATOR_PARTITION_ALLOCATOR_SRC_PARTITION_ALLOC_PARTITION_PAGE_CONSTANTS_H_ |
