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#include "x86_64/memory/scoped_mapping.hpp"
#include "kapi/memory.hpp"
#include "kapi/system.hpp"
#include "x86_64/memory/mmu.hpp"
#include "x86_64/memory/page_table.hpp"
#include "x86_64/memory/page_utilities.hpp"
#include "x86_64/memory/paging_root.hpp"
#include <memory>
#include <utility>
namespace teachos::memory::x86_64
{
scoped_mapping::scoped_mapping(scoped_mapping && other) noexcept
: m_page{std::exchange(other.m_page, page{})}
, m_allocator{std::exchange(other.m_allocator, nullptr)}
, m_mapped{std::exchange(other.m_mapped, false)}
, m_allocated{std::exchange(other.m_allocated, 0)}
{}
scoped_mapping::scoped_mapping(page page, frame_allocator & allocator)
: m_page{page}
, m_allocator{&allocator}
, m_mapped{false}
, m_allocated{}
{
if (paging_root::get().translate(page))
{
system::panic("[MEM] Tried to map a page that is already mapped!");
}
}
scoped_mapping::~scoped_mapping()
{
if (m_mapped)
{
unmap();
x86_64::tlb_flush(m_page.start_address());
}
}
auto scoped_mapping::operator=(scoped_mapping && other) noexcept -> scoped_mapping &
{
if (&other == this)
{
return *this;
}
using std::swap;
swap(m_page, other.m_page);
swap(m_allocator, other.m_allocator);
swap(m_mapped, other.m_mapped);
swap(m_allocated, other.m_allocated);
return *this;
}
auto scoped_mapping::map(frame frame, page_table::entry::flags flags) -> std::byte *
{
auto & pml4 = paging_root::get();
auto pml4_index = pml_index<4>(m_page);
if (!pml4[pml4_index].present())
{
auto new_frame = m_allocator->allocate();
pml4[pml4_index].frame(*new_frame, page_table::entry::flags::present | flags);
std::construct_at(pml4.next(pml4_index).value());
m_allocated |= 1uz << 2;
}
auto pml3 = pml4.next(pml4_index).value();
auto pml3_index = pml_index<3>(m_page);
if (!(*pml3)[pml3_index].present())
{
auto new_frame = m_allocator->allocate();
(*pml3)[pml3_index].frame(*new_frame, page_table::entry::flags::present | flags);
std::construct_at((*pml3).next(pml3_index).value());
m_allocated |= 1uz << 1;
}
auto pml2 = (*pml3).next(pml3_index).value();
auto pml2_index = pml_index<2>(m_page);
if (!(*pml2)[pml2_index].present())
{
auto new_frame = m_allocator->allocate();
(*pml2)[pml2_index].frame(*new_frame, page_table::entry::flags::present | flags);
std::construct_at((*pml2).next(pml2_index).value());
m_allocated |= 1uz << 0;
}
auto pml1 = (*pml2).next(pml2_index).value();
auto pml1_index = pml_index<1>(m_page);
(*pml1)[pml1_index].frame(frame, page_table::entry::flags::present | flags);
m_mapped = true;
return static_cast<std::byte *>(m_page.start_address());
}
auto scoped_mapping::unmap() -> void
{
if (!m_mapped)
{
system::panic("[MEM] Tried to release an unmapped temporary mapping!");
}
auto pml3 = paging_root::get().next(pml_index<4>(m_page)).value();
auto pml2 = pml3->next(pml_index<3>(m_page)).value();
auto pml1 = pml2->next(pml_index<2>(m_page)).value();
if (m_allocated & 1uz << 0)
{
auto pml1_entry = (*pml1)[pml_index<1>(m_page)];
(*pml1)[pml_index<1>(m_page)].clear();
if (pml1->empty())
{
m_allocator->release(pml1_entry.frame().value());
}
}
if (m_allocated & 1uz << 1)
{
auto pml2_entry = (*pml2)[pml_index<2>(m_page)];
(*pml2)[pml_index<2>(m_page)].clear();
if (pml2->empty())
{
m_allocator->release(pml2_entry.frame().value());
}
}
if (m_allocated & 1uz << 2)
{
auto pml3_entry = (*pml3)[pml_index<3>(m_page)];
(*pml3)[pml_index<3>(m_page)].clear();
if (pml3->empty())
{
m_allocator->release(pml3_entry.frame().value());
}
}
m_mapped = false;
}
} // namespace teachos::memory::x86_64
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