mirrors/Atmosphere
1
0
Fork 0
mirror of https://github.com/Atmosphere-NX/Atmosphere.git synced 2025-05-20 09:55:07 -04:00
Code Issues Projects Releases Packages Wiki Activity

kern: refactor FindFreeArea region search logic per 20.0.0 changes

Browse source
This commit is contained in:
Michael Scire 2025-04-30 21:52:01 -07:00 • committed by SciresM
parent b80f0944ab
commit 28296e2aac
3 changed files with 74 additions and 21 deletions
Download patch file Download diff file Expand all files Collapse all files

17
libraries/libmesosphere/source/kern_k_page_table_base.cpp
View file

@ -1333,34 +1333,37 @@ namespace ams::kern {
KProcessAddress KPageTableBase::FindFreeArea(KProcessAddress region_start, size_t region_num_pages, size_t num_pages, size_t alignment, size_t offset, size_t guard_pages) const {
KProcessAddress address = Null<KProcessAddress>;
if (num_pages <= region_num_pages) {
KProcessAddress search_start = Null<KProcessAddress>;
KProcessAddress search_end = Null<KProcessAddress>;
if (m_memory_block_manager.GetRegionForFindFreeArea(std::addressof(search_start), std::addressof(search_end), region_start, region_num_pages, num_pages, alignment, offset, guard_pages)) {
if (this->IsAslrEnabled()) {
/* Try to directly find a free area up to 8 times. */
for (size_t i = 0; i < 8; i++) {
const size_t random_offset = KSystemControl::GenerateRandomRange(0, (region_num_pages - num_pages - guard_pages) * PageSize / alignment) * alignment;
const KProcessAddress candidate = util::AlignDown(GetInteger(region_start + random_offset), alignment) + offset;
const size_t random_offset = KSystemControl::GenerateRandomRange(0, (search_end - search_start) / alignment) * alignment;
const KProcessAddress candidate = search_start + random_offset;
KMemoryBlockManager::const_iterator it = m_memory_block_manager.FindIterator(candidate);
MESOSPHERE_ABORT_UNLESS(it != m_memory_block_manager.end());
if (it->GetState() != KMemoryState_Free) { continue; }
if (!(region_start <= candidate)) { continue; }
if (!(it->GetAddress() + guard_pages * PageSize <= GetInteger(candidate))) { continue; }
if (!(candidate + (num_pages + guard_pages) * PageSize - 1 <= it->GetLastAddress())) { continue; }
if (!(candidate + (num_pages + guard_pages) * PageSize - 1 <= region_start + region_num_pages * PageSize - 1)) { continue; }
address = candidate;
break;
}
/* Fall back to finding the first free area with a random offset. */
if (address == Null<KProcessAddress>) {
/* NOTE: Nintendo does not account for guard pages here. */
/* This may theoretically cause an offset to be chosen that cannot be mapped. */
/* We will account for guard pages. */
const size_t offset_pages = KSystemControl::GenerateRandomRange(0, region_num_pages - num_pages - guard_pages);
address = m_memory_block_manager.FindFreeArea(region_start + offset_pages * PageSize, region_num_pages - offset_pages, num_pages, alignment, offset, guard_pages);
const size_t offset_blocks = KSystemControl::GenerateRandomRange(0, (search_end - search_start) / alignment);
const auto region_end = region_start + region_num_pages * PageSize;
address = m_memory_block_manager.FindFreeArea(search_start + offset_blocks * alignment, (region_end - (search_start + offset_blocks * alignment)) / PageSize, num_pages, alignment, offset, guard_pages);
}
}
/* Find the first free area. */
if (address == Null<KProcessAddress>) {
address = m_memory_block_manager.FindFreeArea(region_start, region_num_pages, num_pages, alignment, offset, guard_pages);