mirror of
https://github.com/Atmosphere-NX/Atmosphere.git
synced 2024-11-15 00:16:48 +00:00
331 lines
14 KiB
C++
331 lines
14 KiB
C++
/*
|
|
* Copyright (c) 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_select_system_control.hpp>
|
|
|
|
namespace ams::kern {
|
|
|
|
class KPageBitmap {
|
|
public:
|
|
class RandomBitGenerator {
|
|
private:
|
|
util::TinyMT m_rng;
|
|
u32 m_entropy;
|
|
u32 m_bits_available;
|
|
private:
|
|
void RefreshEntropy() {
|
|
m_entropy = m_rng.GenerateRandomU32();
|
|
m_bits_available = BITSIZEOF(m_entropy);
|
|
}
|
|
|
|
bool GenerateRandomBit() {
|
|
if (m_bits_available == 0) {
|
|
this->RefreshEntropy();
|
|
}
|
|
|
|
const bool rnd_bit = (m_entropy & 1) != 0;
|
|
m_entropy >>= 1;
|
|
--m_bits_available;
|
|
return rnd_bit;
|
|
}
|
|
|
|
u64 GenerateRandomBits(u32 num_bits) {
|
|
u64 result = 0;
|
|
|
|
/* Iteratively add random bits to our result. */
|
|
while (num_bits > 0) {
|
|
/* Ensure we have random bits to take from. */
|
|
if (m_bits_available == 0) {
|
|
this->RefreshEntropy();
|
|
}
|
|
|
|
/* Determine how many bits to take this round. */
|
|
const auto cur_bits = std::min(num_bits, m_bits_available);
|
|
|
|
/* Generate mask for our current bits. */
|
|
const u64 mask = (static_cast<u64>(1) << cur_bits) - 1;
|
|
|
|
/* Add bits to output from our entropy. */
|
|
result <<= cur_bits;
|
|
result |= (m_entropy & mask);
|
|
|
|
/* Remove bits from our entropy. */
|
|
m_entropy >>= cur_bits;
|
|
m_bits_available -= cur_bits;
|
|
|
|
/* Advance. */
|
|
num_bits -= cur_bits;
|
|
}
|
|
|
|
return result;
|
|
}
|
|
public:
|
|
RandomBitGenerator() : m_entropy(), m_bits_available() {
|
|
m_rng.Initialize(static_cast<u32>(KSystemControl::GenerateRandomU64()));
|
|
}
|
|
|
|
u64 SelectRandomBit(u64 bitmap) {
|
|
u64 selected = 0;
|
|
|
|
for (size_t cur_num_bits = BITSIZEOF(bitmap) / 2; cur_num_bits != 0; cur_num_bits /= 2) {
|
|
const u64 high = (bitmap >> cur_num_bits);
|
|
const u64 low = (bitmap & (~(UINT64_C(0xFFFFFFFFFFFFFFFF) << cur_num_bits)));
|
|
|
|
/* Choose high if we have high and (don't have low or select high randomly). */
|
|
if (high && (low == 0 || this->GenerateRandomBit())) {
|
|
bitmap = high;
|
|
selected += cur_num_bits;
|
|
} else {
|
|
bitmap = low;
|
|
selected += 0;
|
|
}
|
|
}
|
|
|
|
return selected;
|
|
}
|
|
|
|
u64 GenerateRandom(u64 max) {
|
|
/* Determine the number of bits we need. */
|
|
const u64 bits_needed = 1 + (BITSIZEOF(max) - util::CountLeadingZeros(max));
|
|
|
|
/* Generate a random value of the desired bitwidth. */
|
|
const u64 rnd = this->GenerateRandomBits(bits_needed);
|
|
|
|
/* Adjust the value to be in range. */
|
|
return rnd - ((rnd / max) * max);
|
|
}
|
|
};
|
|
public:
|
|
static constexpr size_t MaxDepth = 4;
|
|
private:
|
|
u64 *m_bit_storages[MaxDepth];
|
|
u64 *m_end_storages[MaxDepth];
|
|
RandomBitGenerator m_rng;
|
|
size_t m_num_bits;
|
|
size_t m_used_depths;
|
|
public:
|
|
KPageBitmap() : m_bit_storages(), m_end_storages(), m_rng(), m_num_bits(), m_used_depths() { /* ... */ }
|
|
|
|
constexpr size_t GetNumBits() const { return m_num_bits; }
|
|
constexpr s32 GetHighestDepthIndex() const { return static_cast<s32>(m_used_depths) - 1; }
|
|
|
|
u64 *Initialize(u64 *storage, size_t size) {
|
|
/* Initially, everything is un-set. */
|
|
m_num_bits = 0;
|
|
|
|
/* Calculate the needed bitmap depth. */
|
|
m_used_depths = static_cast<size_t>(GetRequiredDepth(size));
|
|
MESOSPHERE_ASSERT(m_used_depths <= MaxDepth);
|
|
|
|
/* Set the bitmap pointers. */
|
|
for (s32 depth = this->GetHighestDepthIndex(); depth >= 0; depth--) {
|
|
m_bit_storages[depth] = storage;
|
|
size = util::AlignUp(size, BITSIZEOF(u64)) / BITSIZEOF(u64);
|
|
storage += size;
|
|
m_end_storages[depth] = storage;
|
|
}
|
|
|
|
return storage;
|
|
}
|
|
|
|
ssize_t FindFreeBlock(bool random) {
|
|
uintptr_t offset = 0;
|
|
s32 depth = 0;
|
|
|
|
if (random) {
|
|
do {
|
|
const u64 v = m_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) + m_rng.SelectRandomBit(v);
|
|
++depth;
|
|
} while (depth < static_cast<s32>(m_used_depths));
|
|
} else {
|
|
do {
|
|
const u64 v = m_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>(m_used_depths));
|
|
}
|
|
|
|
return static_cast<ssize_t>(offset);
|
|
}
|
|
|
|
ssize_t FindFreeRange(size_t count) {
|
|
/* Check that it is possible to find a range. */
|
|
const u64 * const storage_start = m_bit_storages[m_used_depths - 1];
|
|
const u64 * const storage_end = m_end_storages[m_used_depths - 1];
|
|
|
|
/* If we don't have a storage to iterate (or want more blocks than fit in a single storage), we can't find a free range. */
|
|
if (!(storage_start < storage_end && count <= BITSIZEOF(u64))) {
|
|
return -1;
|
|
}
|
|
|
|
/* Walk the storages to select a random free range. */
|
|
const size_t options_per_storage = std::max<size_t>(BITSIZEOF(u64) / count, 1);
|
|
const size_t num_entries = std::max<size_t>(storage_end - storage_start, 1);
|
|
|
|
const u64 free_mask = (static_cast<u64>(1) << count) - 1;
|
|
|
|
size_t num_valid_options = 0;
|
|
ssize_t chosen_offset = -1;
|
|
for (size_t storage_index = 0; storage_index < num_entries; ++storage_index) {
|
|
u64 storage = storage_start[storage_index];
|
|
for (size_t option = 0; option < options_per_storage; ++option) {
|
|
if ((storage & free_mask) == free_mask) {
|
|
/* We've found a new valid option. */
|
|
++num_valid_options;
|
|
|
|
/* Select the Kth valid option with probability 1/K. This leads to an overall uniform distribution. */
|
|
if (num_valid_options == 1 || m_rng.GenerateRandom(num_valid_options) == 0) {
|
|
/* This is our first option, so select it. */
|
|
chosen_offset = storage_index * BITSIZEOF(u64) + option * count;
|
|
}
|
|
}
|
|
storage >>= count;
|
|
}
|
|
}
|
|
|
|
/* Return the random offset we chose.*/
|
|
return chosen_offset;
|
|
}
|
|
|
|
void SetBit(size_t offset) {
|
|
this->SetBit(this->GetHighestDepthIndex(), offset);
|
|
m_num_bits++;
|
|
}
|
|
|
|
void ClearBit(size_t offset) {
|
|
this->ClearBit(this->GetHighestDepthIndex(), offset);
|
|
m_num_bits--;
|
|
}
|
|
|
|
bool ClearRange(size_t offset, size_t count) {
|
|
s32 depth = this->GetHighestDepthIndex();
|
|
u64 *bits = m_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);
|
|
}
|
|
|
|
m_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(m_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(m_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 CalculateManagementOverheadSize(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);
|
|
}
|
|
};
|
|
|
|
}
|