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UserspaceEmulator: Enable splitting regions at arbitrary points

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This is not yet useful in and of itself, but enables the feature in the next commit.
This commit is contained in:
Ben Wiederhake 2021-03-07 22:37:38 +01:00 • committed by Andreas Kling
parent 7cc8f20a30
commit 45443f24ec
7 changed files with 66 additions and 2 deletions
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32
Userland/DevTools/UserspaceEmulator/SoftMMU.cpp
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@ -61,6 +61,38 @@ void SoftMMU::remove_region(Region& region)
m_regions.remove_first_matching([&](auto& entry) { return entry.ptr() == &region; });
}
void SoftMMU::ensure_split_at(X86::LogicalAddress address)
{
// FIXME: If this fails, call Emulator::dump_backtrace
VERIFY(address.selector() != 0x2b);
u32 offset = address.offset();
VERIFY((offset & (PAGE_SIZE - 1)) == 0);
size_t page_index = address.offset() / PAGE_SIZE;
if (!page_index)
return;
if (m_page_to_region_map[page_index - 1] != m_page_to_region_map[page_index])
return;
if (!m_page_to_region_map[page_index])
return;
// If we get here, we know that the page exists and belongs to a region, that there is
// a previous page, and that it belongs to the same region.
VERIFY(is<MmapRegion>(m_page_to_region_map[page_index]));
MmapRegion* old_region = static_cast<MmapRegion*>(m_page_to_region_map[page_index]);
NonnullOwnPtr<MmapRegion> new_region = old_region->split_at(VirtualAddress(offset));
size_t first_page_in_region = new_region->base() / PAGE_SIZE;
size_t last_page_in_region = (new_region->base() + new_region->size() - 1) / PAGE_SIZE;
for (size_t page = first_page_in_region; page <= last_page_in_region; ++page) {
VERIFY(m_page_to_region_map[page] == old_region);
m_page_to_region_map[page] = new_region.ptr();
}
m_regions.append(move(new_region));
}
void SoftMMU::set_tls_region(NonnullOwnPtr<Region> region)
{
VERIFY(!m_tls_region);