mirror of
https://github.com/Atmosphere-NX/Atmosphere.git
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96 lines
3.5 KiB
C++
96 lines
3.5 KiB
C++
/*
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* Copyright (c) Atmosphère-NX
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms and conditions of the GNU General Public License,
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* version 2, as published by the Free Software Foundation.
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*
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* This program is distributed in the hope it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <exosphere.hpp>
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#include "secmon_smc_common.hpp"
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#include "secmon_random_cache.hpp"
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namespace ams::secmon::smc {
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namespace {
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constinit int g_random_offset_low = 0;
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constinit int g_random_offset_high = 0;
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void FillRandomCache(int offset, int size) {
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/* Get the cache. */
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u8 * const random_cache_loc = GetRandomBytesCache() + offset;
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/* Flush the region we're about to fill to ensure consistency with the SE. */
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hw::FlushDataCache(random_cache_loc, size);
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hw::DataSynchronizationBarrierInnerShareable();
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/* Generate random bytes. */
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se::GenerateRandomBytes(random_cache_loc, size);
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hw::DataSynchronizationBarrierInnerShareable();
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/* Flush to ensure the CPU sees consistent data for the region. */
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hw::FlushDataCache(random_cache_loc, size);
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hw::DataSynchronizationBarrierInnerShareable();
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}
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}
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void FillRandomCache() {
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/* Fill the cache. */
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FillRandomCache(0, GetRandomBytesCacheSize());
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/* Set the extents. */
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g_random_offset_low = 0;
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g_random_offset_high = GetRandomBytesCacheSize() - 1;
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}
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void RefillRandomCache() {
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/* Check that we need to do any refilling. */
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if (const int used_start = (g_random_offset_high + 1) % GetRandomBytesCacheSize(); used_start != g_random_offset_low) {
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if (used_start < g_random_offset_low) {
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/* The region we need to fill is after used_start but before g_random_offset_low. */
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const auto size = g_random_offset_low - used_start;
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FillRandomCache(used_start, size);
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g_random_offset_high += size;
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} else {
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/* We need to fill the space from high to the end and from low to start. */
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const int high_size = GetRandomBytesCacheSize() - used_start;
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if (high_size > 0) {
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FillRandomCache(used_start, high_size);
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g_random_offset_high += high_size;
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}
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const int low_size = g_random_offset_low;
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if (low_size > 0) {
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FillRandomCache(0, low_size);
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g_random_offset_high += low_size;
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}
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}
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g_random_offset_high %= GetRandomBytesCacheSize();
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}
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}
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void GetRandomFromCache(void *dst, size_t size) {
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/* Copy out the requested size. */
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std::memcpy(dst, GetRandomBytesCache() + g_random_offset_low, size);
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/* Advance. */
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g_random_offset_low += size;
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/* Ensure that at all times g_random_offset_low is not within 0x38 bytes of the end of the pool. */
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if (g_random_offset_low + MaxRandomBytes >= GetRandomBytesCacheSize()) {
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g_random_offset_low = 0;
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}
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}
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}
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