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Kernel: Don't relock MM lock for every page when remapping region

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Make sure that callers already hold the MM lock, and we don't have to
worry about reacquiring it every time.
This commit is contained in:
Andreas Kling
2022-01-10 15:08:44 +01:00
parent d7475449cc
commit bdbff9df24
1 changed files with 3 additions and 3 deletions
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6
Kernel/Memory/Region.cpp
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@@ -177,6 +177,8 @@ void Region::set_should_cow(size_t page_index, bool cow)
bool Region::map_individual_page_impl(size_t page_index)
{
VERIFY(m_page_directory->get_lock().is_locked_by_current_processor());
VERIFY(s_mm_lock.is_locked_by_current_processor());
auto page_vaddr = vaddr_from_page_index(page_index);
bool user_allowed = page_vaddr.get() >= USER_RANGE_BASE && is_user_address(page_vaddr);
@@ -184,9 +186,6 @@ bool Region::map_individual_page_impl(size_t page_index)
PANIC("About to map mmap'ed page at a kernel address");
}
// NOTE: We have to take the MM lock for PTE's to stay valid while we use them.
SpinlockLocker mm_locker(s_mm_lock);
auto* pte = MM.ensure_pte(*m_page_directory, page_vaddr);
if (!pte)
return false;
@@ -215,6 +214,7 @@ bool Region::do_remap_vmobject_page(size_t page_index, bool with_flush)
if (!translate_vmobject_page(page_index))
return true; // not an error, region doesn't map this page
SpinlockLocker page_lock(m_page_directory->get_lock());
SpinlockLocker lock(s_mm_lock);
VERIFY(physical_page(page_index));
bool success = map_individual_page_impl(page_index);
if (with_flush)