diff options
Diffstat (limited to 'arch/x86_64/src/memory/paging_root.cpp')
| -rw-r--r-- | arch/x86_64/src/memory/paging_root.cpp | 149 |
1 files changed, 3 insertions, 146 deletions
diff --git a/arch/x86_64/src/memory/paging_root.cpp b/arch/x86_64/src/memory/paging_root.cpp index 078686b..4f88657 100644 --- a/arch/x86_64/src/memory/paging_root.cpp +++ b/arch/x86_64/src/memory/paging_root.cpp @@ -1,161 +1,18 @@ #include "x86_64/memory/paging_root.hpp" -#include "kapi/memory.hpp" -#include "kapi/system.hpp" - -#include "x86_64/memory/page_table.hpp" -#include "x86_64/memory/page_utilities.hpp" -#include "x86_64/memory/scoped_mapping.hpp" - -#include <cstddef> #include <cstdint> -#include <memory> -#include <optional> namespace teachos::memory::x86_64 { namespace { - constexpr auto PML_RECURSIVE_BASE = std::uintptr_t{0177777'776'776'776'776'0000uz}; - - //! Perform the actual mapping of the page, via the recursive page map. - //! - //! On any level above PML1, the entries need to not be no_execute, because the image is densely packed. The entries - //! also need to be writable, since the mapping is being performed through the recursive page map hierarchy. When - //! setting the final entry in the PML1, the actually desired flags are set as is, with the present bit added, thus - //! still enforcing non-writability and non-execution of the affected page. - template<std::size_t Level> - requires(Level > 1uz && Level < 5uz) - auto do_map(recursive_page_table<Level> * pml, page page, page_table::entry::flags flags) - { - auto index = pml_index<Level>(page); - flags = flags & ~page_table::entry::flags::no_execute; - flags = flags | page_table::entry::flags::writable; - if (!(*pml)[index].present()) - { - auto new_table_frame = active_frame_allocator().allocate(); - auto mapping = scoped_mapping{page}; - (*pml)[index].frame(new_table_frame.value(), page_table::entry::flags::present | flags); - auto new_table = std::optional{std::construct_at(*pml->next(index))}; - return new_table; - } - (*pml)[index] |= flags; - return pml->next(index); - } - - //! Perform the actual PML1 update. - auto do_map(page_table * pml, page page, frame frame, page_table::entry::flags flags) -> std::optional<std::byte *> - { - auto index = pml_index<1>(page); - if ((*pml)[index].present()) - { - system::panic("[x86_64:MEM] Tried to map a page that is already mapped"); - } - (*pml)[index].frame(frame, page_table::entry::flags::present | flags); - return std::optional{static_cast<std::byte *>(page.start_address())}; - } + constexpr auto recursive_base = std::uintptr_t{0177777'776'776'776'776'0000uz}; } // namespace - auto paging_root::get() -> paging_root & - { - auto pml4_address = std::bit_cast<paging_root *>(PML_RECURSIVE_BASE); - return *pml4_address; - } - - auto paging_root::translate(linear_address address) const -> std::optional<physical_address> - { - auto offset = address.raw() % page::size; - return translate(page::containing(address)).transform([offset](auto frame) -> auto { - return physical_address{frame.start_address().raw() + offset}; - }); - } - - auto paging_root::translate(page page) const -> std::optional<frame> - { - auto pml3 = next(pml_index<4>(page)); - - if (!pml3) - { - return std::nullopt; - } - - auto handle_huge_page = [&] -> std::optional<frame> { - auto pml3_entry = pml3.transform([&](auto pml3) -> auto { return (*pml3)[pml_index<3>(page)]; }); - if (!pml3_entry) - { - return std::nullopt; - } - else if (pml3_entry->huge()) - { - auto pml3_entry_frame = *pml3_entry->frame(); - return frame{pml3_entry_frame.number() + pml_index<2>(page) * entry_count + pml_index<1>(page)}; - } - - auto pml2 = (*pml3)->next(pml_index<3>(page)); - auto pml2_entry = pml2.transform([&](auto pml2) -> auto { return (*pml2)[pml_index<2>(page)]; }); - if (!pml2_entry) - { - return std::nullopt; - } - else if (pml2_entry->huge()) - { - auto pml2_entry_frame = *pml2_entry->frame(); - return frame{pml2_entry_frame.number() + pml_index<1>(page)}; - } - - return std::nullopt; - }; - - return pml3.and_then([&](auto pml3) -> auto { return pml3->next(pml_index<3>(page)); }) - .and_then([&](auto pml2) -> auto { return pml2->next(pml_index<2>(page)); }) - .and_then([&](auto pml1) -> auto { return (*pml1)[pml_index<1>(page)].frame(); }) - .or_else(handle_huge_page); - } - - auto paging_root::map(page page, frame frame, page_table::entry::flags flags) -> std::optional<std::byte *> + auto paging_root::get() -> paging_root * { - return std::optional{this} - .and_then([&](auto pml) -> auto { return do_map(pml, page, flags); }) - .and_then([&](auto pml) -> auto { return do_map(pml, page, flags); }) - .and_then([&](auto pml) -> auto { return do_map(pml, page, flags); }) - .and_then([&](auto pml) -> auto { return do_map(pml, page, frame, flags); }); - } - - auto paging_root::unmap(page page) -> void - { - if (!this->translate(page)) - { - system::panic("[x86_64:MEM] Tried to unmap a page that was not mapped."); - } - - auto pml4 = this; - auto pml3 = pml4->next(pml_index<4>(page)).value(); - auto pml2 = pml3->next(pml_index<3>(page)).value(); - auto pml1 = pml2->next(pml_index<2>(page)).value(); - - (*pml1)[pml_index<1>(page)].clear(); - - if (pml1->empty()) - { - auto pml1_frame = (*pml2)[pml_index<2>(page)].frame().value(); - active_frame_allocator().release(pml1_frame); - (*pml2)[pml_index<2>(page)].clear(); - } - - if (pml2->empty()) - { - auto pml2_frame = (*pml3)[pml_index<3>(page)].frame().value(); - active_frame_allocator().release(pml2_frame); - (*pml3)[pml_index<3>(page)].clear(); - } - - if (pml3->empty()) - { - auto pml3_frame = (*pml4)[pml_index<4>(page)].frame().value(); - active_frame_allocator().release(pml3_frame); - (*pml4)[pml_index<4>(page)].clear(); - } + return std::bit_cast<paging_root *>(recursive_base); } } // namespace teachos::memory::x86_64
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