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Kernel: Allow contiguous allocations in physical memory

Browse source 
For that, we have a new type of VMObject, called
ContiguousVMObject, that is responsible for allocating contiguous
physical pages.
This commit is contained in:
Liav A 2020-03-07 19:24:41 +02:00 • committed by Andreas Kling
parent b066586355
commit d6e122fd3a
8 changed files with 219 additions and 23 deletions
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70
Kernel/VM/PhysicalRegion.cpp
View file

@ -27,6 +27,7 @@
#include <AK/Bitmap.h>
#include <AK/NonnullRefPtr.h>
#include <AK/RefPtr.h>
#include <AK/Vector.h>
#include <Kernel/Assertions.h>
#include <Kernel/VM/PhysicalPage.h>
#include <Kernel/VM/PhysicalRegion.h>
@ -63,6 +64,51 @@ unsigned PhysicalRegion::finalize_capacity()
return size();
}
Vector<RefPtr<PhysicalPage>> PhysicalRegion::take_contiguous_free_pages(size_t count, bool supervisor)
{
ASSERT(m_pages);
ASSERT(m_used != m_pages);
Vector<RefPtr<PhysicalPage>> physical_pages;
physical_pages.ensure_capacity(count);
auto first_contiguous_page = find_contiguous_free_pages(count);
for (size_t index = 0; index < count; index++) {
physical_pages.append(PhysicalPage::create(m_lower.offset(PAGE_SIZE * (index + first_contiguous_page)), supervisor));
}
return physical_pages;
}
unsigned PhysicalRegion::find_contiguous_free_pages(size_t count)
{
ASSERT(count != 0);
// search from the last page we allocated
auto range = find_and_allocate_contiguous_range(count);
ASSERT(range.has_value());
return range.value();
}
Optional<unsigned> PhysicalRegion::find_and_allocate_contiguous_range(size_t count)
{
ASSERT(count != 0);
size_t found_pages_count = 0;
auto first_index = m_bitmap.find_longest_range_of_unset_bits(count, found_pages_count);
if (!first_index.has_value())
return {};
auto page = first_index.value();
if (count == found_pages_count) {
for (unsigned page_index = page; page_index < (page + count); page_index++) {
m_bitmap.set(page_index, true);
}
m_used += count;
m_last = page + count;
return page;
}
return {};
}
RefPtr<PhysicalPage> PhysicalRegion::take_free_page(bool supervisor)
{
ASSERT(m_pages);
@ -70,29 +116,7 @@ RefPtr<PhysicalPage> PhysicalRegion::take_free_page(bool supervisor)
if (m_used == m_pages)
return nullptr;
// search from the last page we allocated
for (unsigned page = m_last; page < m_pages; page++) {
if (!m_bitmap.get(page)) {
m_bitmap.set(page, true);
m_used++;
m_last = page + 1;
return PhysicalPage::create(m_lower.offset(page * PAGE_SIZE), supervisor);
}
}
// wrap back around to the start in case we missed something
for (unsigned page = 0; page < m_last; page++) {
if (!m_bitmap.get(page)) {
m_bitmap.set(page, true);
m_used++;
m_last = page + 1;
return PhysicalPage::create(m_lower.offset(page * PAGE_SIZE), supervisor);
}
}
ASSERT_NOT_REACHED();
return nullptr;
return PhysicalPage::create(m_lower.offset(find_contiguous_free_pages(1) * PAGE_SIZE), supervisor);
}
void PhysicalRegion::return_page_at(PhysicalAddress addr)