Atmosphere/libraries/libmesosphere/include/mesosphere/kern_k_page_heap.hpp

163 lines
8.1 KiB
C++

/*
* Copyright (c) 2018-2020 Atmosphère-NX
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#pragma once
#include <mesosphere/kern_common.hpp>
#include <mesosphere/kern_k_page_bitmap.hpp>
namespace ams::kern {
class KPageHeap {
private:
static constexpr inline size_t MemoryBlockPageShifts[] = { 0xC, 0x10, 0x15, 0x16, 0x19, 0x1D, 0x1E };
static constexpr size_t NumMemoryBlockPageShifts = util::size(MemoryBlockPageShifts);
public:
static constexpr s32 GetAlignedBlockIndex(size_t num_pages, size_t align_pages) {
const size_t target_pages = std::max(num_pages, align_pages);
for (size_t i = 0; i < NumMemoryBlockPageShifts; i++) {
if (target_pages <= (size_t(1) << MemoryBlockPageShifts[i]) / PageSize) {
return static_cast<s32>(i);
}
}
return -1;
}
static constexpr s32 GetBlockIndex(size_t num_pages) {
for (s32 i = static_cast<s32>(NumMemoryBlockPageShifts) - 1; i >= 0; i--) {
if (num_pages >= (size_t(1) << MemoryBlockPageShifts[i]) / PageSize) {
return i;
}
}
return -1;
}
static constexpr size_t GetBlockSize(size_t index) {
return size_t(1) << MemoryBlockPageShifts[index];
}
static constexpr size_t GetBlockNumPages(size_t index) {
return GetBlockSize(index) / PageSize;
}
private:
class Block {
private:
KPageBitmap bitmap;
KVirtualAddress heap_address;
uintptr_t end_offset;
size_t block_shift;
size_t next_block_shift;
public:
Block() : bitmap(), heap_address(), end_offset(), block_shift(), next_block_shift() { /* ... */ }
constexpr size_t GetShift() const { return this->block_shift; }
constexpr size_t GetNextShift() const { return this->next_block_shift; }
constexpr size_t GetSize() const { return u64(1) << this->GetShift(); }
constexpr size_t GetNumPages() const { return this->GetSize() / PageSize; }
constexpr size_t GetNumFreeBlocks() const { return this->bitmap.GetNumBits(); }
constexpr size_t GetNumFreePages() const { return this->GetNumFreeBlocks() * this->GetNumPages(); }
u64 *Initialize(KVirtualAddress addr, size_t size, size_t bs, size_t nbs, u64 *bit_storage) {
/* Set shifts. */
this->block_shift = bs;
this->next_block_shift = nbs;
/* Align up the address. */
KVirtualAddress end = addr + size;
const size_t align = (this->next_block_shift != 0) ? (u64(1) << this->next_block_shift) : (u64(1) << this->block_shift);
addr = util::AlignDown(GetInteger(addr), align);
end = util::AlignUp(GetInteger(end), align);
this->heap_address = addr;
this->end_offset = (end - addr) / (u64(1) << this->block_shift);
return this->bitmap.Initialize(bit_storage, this->end_offset);
}
KVirtualAddress PushBlock(KVirtualAddress address) {
/* Set the bit for the free block. */
size_t offset = (address - this->heap_address) >> this->GetShift();
this->bitmap.SetBit(offset);
/* If we have a next shift, try to clear the blocks below this one and return the new address. */
if (this->GetNextShift()) {
const size_t diff = u64(1) << (this->GetNextShift() - this->GetShift());
offset = util::AlignDown(offset, diff);
if (this->bitmap.ClearRange(offset, diff)) {
return this->heap_address + (offset << this->GetShift());
}
}
/* We couldn't coalesce, or we're already as big as possible. */
return Null<KVirtualAddress>;
}
KVirtualAddress PopBlock(bool random) {
/* Find a free block. */
ssize_t soffset = this->bitmap.FindFreeBlock(random);
if (soffset < 0) {
return Null<KVirtualAddress>;
}
const size_t offset = static_cast<size_t>(soffset);
/* Update our tracking and return it. */
this->bitmap.ClearBit(offset);
return this->heap_address + (offset << this->GetShift());
}
public:
static constexpr size_t CalculateMetadataOverheadSize(size_t region_size, size_t cur_block_shift, size_t next_block_shift) {
const size_t cur_block_size = (u64(1) << cur_block_shift);
const size_t next_block_size = (u64(1) << next_block_shift);
const size_t align = (next_block_shift != 0) ? next_block_size : cur_block_size;
return KPageBitmap::CalculateMetadataOverheadSize((align * 2 + util::AlignUp(region_size, align)) / cur_block_size);
}
};
private:
KVirtualAddress heap_address;
size_t heap_size;
size_t used_size;
size_t num_blocks;
Block blocks[NumMemoryBlockPageShifts];
private:
void Initialize(KVirtualAddress heap_address, size_t heap_size, KVirtualAddress metadata_address, size_t metadata_size, const size_t *block_shifts, size_t num_block_shifts);
size_t GetNumFreePages() const;
void FreeBlock(KVirtualAddress block, s32 index);
public:
KPageHeap() : heap_address(), heap_size(), used_size(), num_blocks(), blocks() { /* ... */ }
constexpr KVirtualAddress GetAddress() const { return this->heap_address; }
constexpr size_t GetSize() const { return this->heap_size; }
constexpr KVirtualAddress GetEndAddress() const { return this->GetAddress() + this->GetSize(); }
constexpr size_t GetPageOffset(KVirtualAddress block) const { return (block - this->GetAddress()) / PageSize; }
void Initialize(KVirtualAddress heap_address, size_t heap_size, KVirtualAddress metadata_address, size_t metadata_size) {
return Initialize(heap_address, heap_size, metadata_address, metadata_size, MemoryBlockPageShifts, NumMemoryBlockPageShifts);
}
void UpdateUsedSize() {
this->used_size = this->heap_size - (this->GetNumFreePages() * PageSize);
}
KVirtualAddress AllocateBlock(s32 index, bool random);
void Free(KVirtualAddress addr, size_t num_pages);
private:
static size_t CalculateMetadataOverheadSize(size_t region_size, const size_t *block_shifts, size_t num_block_shifts);
public:
static size_t CalculateMetadataOverheadSize(size_t region_size) {
return CalculateMetadataOverheadSize(region_size, MemoryBlockPageShifts, NumMemoryBlockPageShifts);
}
};
}