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

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/*
* 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>
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:
class Bitmap {
public:
static constexpr size_t MaxDepth = 4;
private:
u64 *bit_storages[MaxDepth];
size_t num_bits;
size_t used_depths;
public:
constexpr Bitmap() : bit_storages(), num_bits(), used_depths() { /* ... */ }
constexpr size_t GetNumBits() const { return this->num_bits; }
constexpr s32 GetHighestDepthIndex() const { return static_cast<s32>(this->used_depths) - 1; }
u64 *Initialize(u64 *storage, size_t size) {
/* Initially, everything is un-set. */
this->num_bits = 0;
/* Calculate the needed bitmap depth. */
this->used_depths = static_cast<size_t>(GetRequiredDepth(size));
MESOSPHERE_ASSERT(this->used_depths <= MaxDepth);
/* Set the bitmap pointers. */
for (s32 depth = this->GetHighestDepthIndex(); depth >= 0; depth--) {
this->bit_storages[depth] = storage;
size = util::AlignUp(size, BITSIZEOF(u64)) / BITSIZEOF(u64);
storage += size;
}
return storage;
}
ssize_t FindFreeBlock() const {
uintptr_t offset = 0;
s32 depth = 0;
do {
const u64 v = this->bit_storages[depth][offset];
if (v == 0) {
/* If depth is bigger than zero, then a previous level indicated a block was free. */
MESOSPHERE_ASSERT(depth == 0);
return -1;
}
offset = offset * BITSIZEOF(u64) + __builtin_ctzll(v);
++depth;
} while (depth < static_cast<s32>(this->used_depths));
return static_cast<ssize_t>(offset);
}
void SetBit(size_t offset) {
this->SetBit(this->GetHighestDepthIndex(), offset);
this->num_bits++;
}
void ClearBit(size_t offset) {
this->ClearBit(this->GetHighestDepthIndex(), offset);
this->num_bits--;
}
bool ClearRange(size_t offset, size_t count) {
s32 depth = this->GetHighestDepthIndex();
u64 *bits = this->bit_storages[depth];
size_t bit_ind = offset / BITSIZEOF(u64);
if (AMS_LIKELY(count < BITSIZEOF(u64))) {
const size_t shift = offset % BITSIZEOF(u64);
MESOSPHERE_ASSERT(shift + count <= BITSIZEOF(u64));
/* Check that all the bits are set. */
const u64 mask = ((u64(1) << count) - 1) << shift;
u64 v = bits[bit_ind];
if ((v & mask) != mask) {
return false;
}
/* Clear the bits. */
v &= ~mask;
bits[bit_ind] = v;
if (v == 0) {
this->ClearBit(depth - 1, bit_ind);
}
} else {
MESOSPHERE_ASSERT(offset % BITSIZEOF(u64) == 0);
MESOSPHERE_ASSERT(count % BITSIZEOF(u64) == 0);
/* Check that all the bits are set. */
size_t remaining = count;
size_t i = 0;
do {
if (bits[bit_ind + i++] != ~u64(0)) {
return false;
}
remaining -= BITSIZEOF(u64);
} while (remaining > 0);
/* Clear the bits. */
remaining = count;
i = 0;
do {
bits[bit_ind + i] = 0;
this->ClearBit(depth - 1, bit_ind + i);
i++;
remaining -= BITSIZEOF(u64);
} while (remaining > 0);
}
this->num_bits -= count;
return true;
}
private:
void SetBit(s32 depth, size_t offset) {
while (depth >= 0) {
size_t ind = offset / BITSIZEOF(u64);
size_t which = offset % BITSIZEOF(u64);
const u64 mask = u64(1) << which;
u64 *bit = std::addressof(this->bit_storages[depth][ind]);
u64 v = *bit;
MESOSPHERE_ASSERT((v & mask) == 0);
*bit = v | mask;
if (v) {
break;
}
offset = ind;
depth--;
}
}
void ClearBit(s32 depth, size_t offset) {
while (depth >= 0) {
size_t ind = offset / BITSIZEOF(u64);
size_t which = offset % BITSIZEOF(u64);
const u64 mask = u64(1) << which;
u64 *bit = std::addressof(this->bit_storages[depth][ind]);
u64 v = *bit;
MESOSPHERE_ASSERT((v & mask) != 0);
v &= ~mask;
*bit = v;
if (v) {
break;
}
offset = ind;
depth--;
}
}
private:
static constexpr s32 GetRequiredDepth(size_t region_size) {
s32 depth = 0;
while (true) {
region_size /= BITSIZEOF(u64);
depth++;
if (region_size == 0) {
return depth;
}
}
}
public:
static constexpr size_t CalculateMetadataOverheadSize(size_t region_size) {
size_t overhead_bits = 0;
for (s32 depth = GetRequiredDepth(region_size) - 1; depth >= 0; depth--) {
region_size = util::AlignUp(region_size, BITSIZEOF(u64)) / BITSIZEOF(u64);
overhead_bits += region_size;
}
return overhead_bits * sizeof(u64);
}
};
private:
Bitmap bitmap;
KVirtualAddress heap_address;
uintptr_t end_offset;
size_t block_shift;
size_t next_block_shift;
public:
constexpr 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() {
/* Find a free block. */
ssize_t soffset = this->bitmap.FindFreeBlock();
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 Bitmap::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:
constexpr 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);
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);
}
};
}
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