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[crypto] Rework AES CTR/XTS streaming and squash heap churn (#2782) 

AES Updates:
Replaced heap churn with stack scratch buffers tail handling now stays in-place, no more recursive transcode detours.
CTR/XTS modes read in larger, aligned chunks and still handle odd offsets cleanly.
XTS prefetches a few sectors ahead to reduce extra reads.
AesCtrStorage writer now uses the pooled buffer properly one stack slab, chunk forward, bump counter, repeat.
Result: less malloc noise, fewer watchdog spikes at startup (though mbedtls still sets the pace).
This should make the loading speed slightly better than before. Make sure to test.

Reviewed-on: https://git.eden-emu.dev/eden-emu/eden/pulls/2782
Reviewed-by: MaranBr <maranbr@eden-emu.dev>
Reviewed-by: crueter <crueter@eden-emu.dev>
Co-authored-by: godpow <thesaviorsrule@yahoo.com>
Co-committed-by: godpow <thesaviorsrule@yahoo.com>
This commit is contained in:
godpow 2025-10-26 02:12:27 +01:00 committed by crueter
parent 73ebf59af7
commit 41e15e95b1
No known key found for this signature in database
GPG Key ID: 425ACD2D4830EBC6
5 changed files with 167 additions and 115 deletions
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64
src/core/crypto/aes_util.cpp
View File

@ -4,8 +4,9 @@
// SPDX-FileCopyrightText: Copyright 2018 yuzu Emulator Project
// SPDX-License-Identifier: GPL-2.0-or-later
#include <algorithm>
#include <array>
#include <vector>
#include <cstring>
#include <mbedtls/cipher.h>
#include "common/assert.h"
#include "common/logging/log.h"
@ -15,6 +16,7 @@
namespace Core::Crypto {
namespace {
using NintendoTweak = std::array<u8, 16>;
constexpr std::size_t AesBlockBytes = 16;
NintendoTweak CalculateNintendoTweak(std::size_t sector_id) {
NintendoTweak out{};
@ -75,39 +77,51 @@ void AESCipher<Key, KeySize>::Transcode(const u8* src, std::size_t size, u8* des
mbedtls_cipher_reset(context);
// Only ECB strictly requires block sized chunks.
if (size == 0)
return;
const auto mode = mbedtls_cipher_get_cipher_mode(context);
std::size_t written = 0;
if (mbedtls_cipher_get_cipher_mode(context) != MBEDTLS_MODE_ECB) {
mbedtls_cipher_update(context, src, size, dest, &written);
if (written != size)
if (mode != MBEDTLS_MODE_ECB) {
const int ret = mbedtls_cipher_update(context, src, size, dest, &written);
ASSERT(ret == 0);
if (written != size) {
LOG_WARNING(Crypto, "Not all data was processed requested={:016X}, actual={:016X}.", size, written);
}
return;
}
// ECB path: operate in block sized chunks and mirror previous behavior.
const auto block_size = mbedtls_cipher_get_block_size(context);
if (size < block_size) {
std::vector<u8> block(block_size);
std::memcpy(block.data(), src, size);
Transcode(block.data(), block.size(), block.data(), op);
std::memcpy(dest, block.data(), size);
return;
}
ASSERT(block_size <= AesBlockBytes);
for (std::size_t offset = 0; offset < size; offset += block_size) {
const auto length = std::min<std::size_t>(block_size, size - offset);
mbedtls_cipher_update(context, src + offset, length, dest + offset, &written);
if (written != length) {
if (length < block_size) {
std::vector<u8> block(block_size);
std::memcpy(block.data(), src + offset, length);
Transcode(block.data(), block.size(), block.data(), op);
std::memcpy(dest + offset, block.data(), length);
return;
}
LOG_WARNING(Crypto, "Not all data was processed requested={:016X}, actual={:016X}.", length, written);
const std::size_t whole_block_bytes = size - (size % block_size);
if (whole_block_bytes != 0) {
const int ret = mbedtls_cipher_update(context, src, whole_block_bytes, dest, &written);
ASSERT(ret == 0);
if (written != whole_block_bytes) {
LOG_WARNING(Crypto, "Not all data was processed requested={:016X}, actual={:016X}.",
whole_block_bytes, written);
}
}
const std::size_t tail = size - whole_block_bytes;
if (tail == 0)
return;
std::array<u8, AesBlockBytes> tail_buffer{};
std::memcpy(tail_buffer.data(), src + whole_block_bytes, tail);
std::size_t tail_written = 0;
const int ret = mbedtls_cipher_update(context, tail_buffer.data(), block_size, tail_buffer.data(),
&tail_written);
ASSERT(ret == 0);
if (tail_written != block_size) {
LOG_WARNING(Crypto, "Not all data was processed requested={:016X}, actual={:016X}.", block_size,
tail_written);
}
std::memcpy(dest + whole_block_bytes, tail_buffer.data(), tail);
}
template <typename Key, std::size_t KeySize>

100
src/core/crypto/ctr_encryption_layer.cpp
View File

@ -5,6 +5,7 @@
// SPDX-License-Identifier: GPL-2.0-or-later
#include <algorithm>
#include <array>
#include <cstring>
#include "core/crypto/ctr_encryption_layer.h"
@ -18,35 +19,84 @@ std::size_t CTREncryptionLayer::Read(u8* data, std::size_t length, std::size_t o
if (length == 0)
return 0;
constexpr std::size_t BlockSize = 0x10;
constexpr std::size_t MaxChunkSize = 0x10000;
std::size_t total_read = 0;
// Handle an initial misaligned portion if needed.
if (auto const sector_offset = offset & 0xF; sector_offset != 0) {
const std::size_t aligned_off = offset - sector_offset;
std::array<u8, 0x10> block{};
if (auto const got = base->Read(block.data(), block.size(), aligned_off); got != 0) {
UpdateIV(base_offset + aligned_off);
cipher.Transcode(block.data(), got, block.data(), Op::Decrypt);
auto const to_copy = std::min<std::size_t>(length, got > sector_offset ? got - sector_offset : 0);
if (to_copy > 0) {
std::memcpy(data, block.data() + sector_offset, to_copy);
data += to_copy;
offset += to_copy;
length -= to_copy;
total_read += to_copy;
}
} else {
return 0;
auto* out = data;
std::size_t remaining = length;
std::size_t current_offset = offset;
const auto read_exact = [this](u8* dst, std::size_t bytes, std::size_t src_offset) {
std::size_t filled = 0;
while (filled < bytes) {
const std::size_t got = base->Read(dst + filled, bytes - filled, src_offset + filled);
if (got == 0)
break;
filled += got;
}
return filled;
};
if (const std::size_t intra_block = current_offset & (BlockSize - 1); intra_block != 0) {
std::array<u8, BlockSize> block{};
const std::size_t aligned_offset = current_offset - intra_block;
const std::size_t got = read_exact(block.data(), BlockSize, aligned_offset);
if (got <= intra_block)
return total_read;
UpdateIV(base_offset + aligned_offset);
cipher.Transcode(block.data(), got, block.data(), Op::Decrypt);
const std::size_t available = got - intra_block;
const std::size_t to_copy = std::min<std::size_t>(remaining, available);
std::memcpy(out, block.data() + intra_block, to_copy);
out += to_copy;
current_offset += to_copy;
remaining -= to_copy;
total_read += to_copy;
if (to_copy != available)
return total_read;
}
if (length > 0) {
// Now aligned to 0x10
UpdateIV(base_offset + offset);
const std::size_t got = base->Read(data, length, offset);
if (got > 0) {
cipher.Transcode(data, got, data, Op::Decrypt);
total_read += got;
}
while (remaining >= BlockSize) {
const std::size_t chunk_request = std::min<std::size_t>(remaining, MaxChunkSize);
const std::size_t aligned_request = chunk_request - (chunk_request % BlockSize);
if (aligned_request == 0)
break;
const std::size_t got = read_exact(out, aligned_request, current_offset);
if (got == 0)
break;
UpdateIV(base_offset + current_offset);
cipher.Transcode(out, got, out, Op::Decrypt);
out += got;
current_offset += got;
remaining -= got;
total_read += got;
if (got < aligned_request)
return total_read;
}
if (remaining > 0) {
std::array<u8, BlockSize> block{};
const std::size_t got = read_exact(block.data(), BlockSize, current_offset);
if (got == 0)
return total_read;
UpdateIV(base_offset + current_offset);
cipher.Transcode(block.data(), got, block.data(), Op::Decrypt);
const std::size_t to_copy = std::min<std::size_t>(remaining, got);
std::memcpy(out, block.data(), to_copy);
total_read += to_copy;
}
return total_read;
}

92
src/core/crypto/xts_encryption_layer.cpp
View File

@ -20,67 +20,49 @@ std::size_t XTSEncryptionLayer::Read(u8* data, std::size_t length, std::size_t o
if (length == 0)
return 0;
constexpr std::size_t PrefetchSectors = 4;
auto* out = data;
std::size_t remaining = length;
std::size_t current_offset = offset;
std::size_t total_read = 0;
// Handle initial unaligned part within a sector.
if (auto const sector_offset = offset % XTS_SECTOR_SIZE; sector_offset != 0) {
const std::size_t aligned_off = offset - sector_offset;
std::array<u8, XTS_SECTOR_SIZE> block{};
if (auto const got = base->Read(block.data(), XTS_SECTOR_SIZE, aligned_off); got > 0) {
if (got < XTS_SECTOR_SIZE)
std::memset(block.data() + got, 0, XTS_SECTOR_SIZE - got);
cipher.XTSTranscode(block.data(), XTS_SECTOR_SIZE, block.data(), aligned_off / XTS_SECTOR_SIZE,
XTS_SECTOR_SIZE, Op::Decrypt);
auto const to_copy = std::min<std::size_t>(length, got > sector_offset ? got - sector_offset : 0);
if (to_copy > 0) {
std::memcpy(data, block.data() + sector_offset, to_copy);
data += to_copy;
offset += to_copy;
length -= to_copy;
total_read += to_copy;
}
} else {
return 0;
}
}
std::array<u8, XTS_SECTOR_SIZE> sector{};
if (length > 0) {
// Process aligned middle inplace, in sector sized multiples.
while (length >= XTS_SECTOR_SIZE) {
const std::size_t req = (length / XTS_SECTOR_SIZE) * XTS_SECTOR_SIZE;
const std::size_t got = base->Read(data, req, offset);
if (got == 0) {
while (remaining > 0) {
const std::size_t sector_index = current_offset / XTS_SECTOR_SIZE;
const std::size_t sector_offset = current_offset % XTS_SECTOR_SIZE;
const std::size_t sectors_to_read = std::min<std::size_t>(PrefetchSectors,
(remaining + sector_offset +
XTS_SECTOR_SIZE - 1) /
XTS_SECTOR_SIZE);
for (std::size_t s = 0; s < sectors_to_read && remaining > 0; ++s) {
const std::size_t index = sector_index + s;
const std::size_t read_offset = index * XTS_SECTOR_SIZE;
const std::size_t got = base->Read(sector.data(), XTS_SECTOR_SIZE, read_offset);
if (got == 0)
return total_read;
}
const std::size_t got_rounded = got - (got % XTS_SECTOR_SIZE);
if (got_rounded > 0) {
cipher.XTSTranscode(data, got_rounded, data, offset / XTS_SECTOR_SIZE, XTS_SECTOR_SIZE, Op::Decrypt);
data += got_rounded;
offset += got_rounded;
length -= got_rounded;
total_read += got_rounded;
}
// If we didn't get a full sector next, break to handle tail.
if (got_rounded != got) {
break;
}
}
// Handle tail within a sector, if any.
if (length > 0) {
std::array<u8, XTS_SECTOR_SIZE> block{};
const std::size_t got = base->Read(block.data(), XTS_SECTOR_SIZE, offset);
if (got > 0) {
if (got < XTS_SECTOR_SIZE) {
std::memset(block.data() + got, 0, XTS_SECTOR_SIZE - got);
}
cipher.XTSTranscode(block.data(), XTS_SECTOR_SIZE, block.data(),
offset / XTS_SECTOR_SIZE, XTS_SECTOR_SIZE, Op::Decrypt);
const std::size_t to_copy = std::min<std::size_t>(length, got);
std::memcpy(data, block.data(), to_copy);
total_read += to_copy;
}
if (got < XTS_SECTOR_SIZE)
std::memset(sector.data() + got, 0, XTS_SECTOR_SIZE - got);
cipher.XTSTranscode(sector.data(), XTS_SECTOR_SIZE, sector.data(), index, XTS_SECTOR_SIZE,
Op::Decrypt);
const std::size_t local_offset = (s == 0) ? sector_offset : 0;
const std::size_t available = XTS_SECTOR_SIZE - local_offset;
const std::size_t to_copy = std::min<std::size_t>(available, remaining);
std::memcpy(out, sector.data() + local_offset, to_copy);
out += to_copy;
current_offset += to_copy;
remaining -= to_copy;
total_read += to_copy;
}
}
return total_read;
}
} // namespace Core::Crypto

21
src/core/file_sys/fssystem/fssystem_aes_ctr_storage.cpp
View File

@ -86,18 +86,21 @@ size_t AesCtrStorage::Write(const u8* buffer, size_t size, size_t offset) {
// Loop until all data is written using a pooled buffer residing on the stack (blocksize = 0x10)
boost::container::static_vector<u8, BlockSize> pooled_buffer;
for (size_t remaining = size; remaining > 0; ) {
// Determine data we're writing and where.
auto const write_size = (std::min)(pooled_buffer.size(), remaining);
u8* write_buf = pooled_buffer.data();
pooled_buffer.resize(BlockSize);
const u8* cur = buffer;
size_t remaining = size;
size_t current_offset = offset;
while (remaining > 0) {
const size_t write_size = std::min<std::size_t>(pooled_buffer.size(), remaining);
// Encrypt the data and then write it.
m_cipher->SetIV(ctr);
m_cipher->Transcode(buffer, write_size, write_buf, Core::Crypto::Op::Encrypt);
m_base_storage->Write(write_buf, write_size, offset);
m_cipher->Transcode(cur, write_size, pooled_buffer.data(), Core::Crypto::Op::Encrypt);
m_base_storage->Write(pooled_buffer.data(), write_size, current_offset);
// Advance next write chunk
offset += write_size;
cur += write_size;
current_offset += write_size;
remaining -= write_size;
if (remaining > 0)
AddCounter(ctr.data(), IvSize, write_size / BlockSize);

5
src/core/file_sys/fssystem/fssystem_aes_xts_storage.cpp
View File

@ -65,10 +65,13 @@ size_t AesXtsStorage::Read(u8* buffer, size_t size, size_t offset) const {
if ((offset % m_block_size) != 0) {
// Decrypt into our pooled stack buffer (max bound = NCA::XtsBlockSize)
boost::container::static_vector<u8, NcaHeader::XtsBlockSize> tmp_buf;
ASSERT(m_block_size <= tmp_buf.max_size());
tmp_buf.resize(m_block_size);
// Determine the size of the pre-data read.
auto const skip_size = size_t(offset - Common::AlignDown(offset, m_block_size));
auto const data_size = (std::min)(size, m_block_size - skip_size);
std::fill_n(tmp_buf.begin(), skip_size, u8{0});
if (skip_size > 0)
std::fill_n(tmp_buf.begin(), skip_size, u8{0});
std::memcpy(tmp_buf.data() + skip_size, buffer, data_size);
m_cipher->SetIV(ctr);
m_cipher->Transcode(tmp_buf.data(), m_block_size, tmp_buf.data(), Core::Crypto::Op::Decrypt);