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#include "kapi/memory.hpp"
#include "kapi/boot.hpp"
#include "kapi/memory/buffered_allocator.hpp"
#include "kapi/system.hpp"
#include "arch/boot/boot.hpp"
#include "arch/boot/ld.hpp"
#include "arch/cpu/registers.hpp"
#include "arch/memory/kernel_mapper.hpp"
#include "arch/memory/mmu.hpp"
#include "arch/memory/page_table.hpp"
#include "arch/memory/page_utilities.hpp"
#include "arch/memory/paging_root.hpp"
#include "arch/memory/recursive_page_mapper.hpp"
#include "arch/memory/region_allocator.hpp"
#include "arch/memory/scoped_mapping.hpp"
#include <kstd/print>
#include <multiboot2/constants.hpp>
#include <multiboot2/information.hpp>
#include <algorithm>
#include <atomic>
#include <bit>
#include <cstddef>
#include <cstdint>
#include <memory>
#include <optional>
#include <ranges>
#include <span>
#include <utility>
namespace kapi::memory
{
namespace
{
constexpr auto static unused_page_address = linear_address{0x0000'7fff'cafe'faceuz};
constexpr auto static recursive_page_map_index = arch::memory::page_table::entry_count - 2;
auto constinit region_based_allocator = std::optional<arch::memory::region_allocator>{};
auto constinit allocation_buffer = std::optional<buffered_allocator<4>>{};
auto constinit recursive_page_mapper = std::optional<arch::memory::recursive_page_mapper>{};
//! Instantiate a basic, memory region based, early frame allocator for remapping.
auto collect_memory_information()
{
auto memory_map = boot::bootstrap_information.mbi->maybe_memory_map();
if (!memory_map)
{
system::panic("[x86_64] Failed to create early allocator, no memory map available.");
}
auto const & mbi = boot::bootstrap_information.mbi;
auto mbi_span = std::span{std::bit_cast<std::byte *>(mbi), mbi->size_bytes()};
auto image_span = std::span{&arch::boot::_start_physical, &arch::boot::_end_physical};
return arch::memory::region_allocator::memory_information{
.image_range = std::make_pair(physical_address{&image_span.front()}, physical_address{&image_span.back()}),
.mbi_range = std::make_pair(physical_address{&mbi_span.front()}, physical_address{&mbi_span.back()}),
.memory_map = *memory_map,
};
}
//! Enable additional CPU protection features, required during later stages of the kernel.
auto enable_cpu_protections() -> void
{
arch::cpu::cr0::set(arch::cpu::cr0::flags::write_protect);
arch::cpu::i32_efer::set(arch::cpu::i32_efer::flags::execute_disable_bit_enable);
}
//! Inject, or graft, a faux recursive PML4 into the active page mapping structure.
auto inject_faux_pml4(frame_allocator & allocator, page_mapper & mapper)
{
using arch::memory::page_table;
using arch::memory::paging_root;
using arch::memory::pml_index;
using entry_flags = arch::memory::page_table::entry::flags;
auto page = page::containing(unused_page_address);
auto temporary_mapper = arch::memory::scoped_mapping{page, mapper};
auto new_pml4_frame = allocator.allocate();
auto pml4 = std::construct_at(temporary_mapper.map_as<page_table>(*new_pml4_frame, entry_flags::writable));
(*pml4)[recursive_page_map_index].frame(new_pml4_frame.value(), entry_flags::present | entry_flags::writable);
auto pml4_index = pml_index<4>(page);
auto old_pml4 = paging_root::get();
auto pml4_entry = (*old_pml4)[pml4_index];
auto pml3_index = pml_index<3>(page);
auto old_pml3 = old_pml4->next(pml4_index);
auto pml3_entry = (**old_pml3)[pml3_index];
auto pml2_index = pml_index<2>(page);
auto old_pml2 = (**old_pml3).next(pml3_index);
auto pml2_entry = (**old_pml2)[pml2_index];
auto pml1_index = pml_index<1>(page);
auto old_pml1 = (**old_pml2).next(pml2_index);
auto pml1_entry = (**old_pml1)[pml1_index];
(*paging_root::get())[recursive_page_map_index].frame(new_pml4_frame.value(),
entry_flags::present | entry_flags::writable);
arch::memory::tlb_flush_all();
auto new_pml4 = paging_root::get();
(*new_pml4)[pml4_index] = pml4_entry;
auto new_pml3 = new_pml4->next(pml4_index);
(**new_pml3)[pml3_index] = pml3_entry;
auto new_pml2 = (**new_pml3).next(pml3_index);
(**new_pml2)[pml2_index] = pml2_entry;
auto new_pml1 = (**new_pml2).next(pml2_index);
(**new_pml1)[pml1_index] = pml1_entry;
return *new_pml4_frame;
}
auto remap_kernel(page_mapper & mapper) -> void
{
auto kernel_mapper = arch::memory::kernel_mapper{boot::bootstrap_information.mbi};
kernel_mapper.remap_kernel(mapper);
}
auto remap_vga_text_mode_buffer(page_mapper & mapper) -> void
{
constexpr auto vga_base = std::uintptr_t{0xb8000};
auto vga_physical_start = physical_address{vga_base};
auto vga_virtual_start = linear_address{vga_base + std::bit_cast<std::uintptr_t>(&arch::boot::TEACHOS_VMA)};
auto page = page::containing(vga_virtual_start);
auto frame = frame::containing(vga_physical_start);
mapper.map(page, frame, page_mapper::flags::writable);
}
auto remap_multiboot_information(page_mapper & mapper) -> void
{
auto mbi_base = std::bit_cast<std::uintptr_t>(boot::bootstrap_information.mbi);
auto mbi_size = boot::bootstrap_information.mbi->size_bytes();
auto mbi_physical_start = physical_address{mbi_base & ~std::bit_cast<std::uintptr_t>(&arch::boot::TEACHOS_VMA)};
auto mbi_virtual_start = linear_address{mbi_base};
auto mbi_block_count = (mbi_size + PLATFORM_FRAME_SIZE - 1) / PLATFORM_FRAME_SIZE;
for (auto i = 0uz; i < mbi_block_count; ++i)
{
auto page = page::containing(mbi_virtual_start) + i;
auto frame = frame::containing(mbi_physical_start) + i;
mapper.map(page, frame, page_mapper::flags::empty);
}
}
auto handoff_to_kernel_pmm(frame_allocator & new_allocator) -> void
{
auto memory_map = boot::bootstrap_information.mbi->memory_map();
for (auto const & region : memory_map.regions() | std::views::filter([](auto const & region) {
return region.type == multiboot2::memory_type::available;
}))
{
auto start = frame::containing(physical_address{region.base});
auto count = region.size_in_B / page::size;
new_allocator.release_many({start, count});
}
auto next_free_frame = region_based_allocator->next_free_frame();
if (!next_free_frame)
{
system::panic("[x86_64:MEM] No more free memory!");
}
std::ranges::for_each(std::views::iota(kapi::memory::frame{}, *next_free_frame),
[&](auto frame) { new_allocator.mark_used(frame); });
auto image_start = frame::containing(physical_address{&arch::boot::_start_physical});
auto image_end = frame::containing(physical_address{&arch::boot::_end_physical}) + 1;
std::ranges::for_each(std::views::iota(image_start, image_end),
[&](auto frame) { new_allocator.mark_used(frame); });
auto mbi_base = std::bit_cast<std::uintptr_t>(boot::bootstrap_information.mbi);
auto mbi_size = boot::bootstrap_information.mbi->size_bytes();
auto mbi_address = physical_address{mbi_base & ~std::bit_cast<std::uintptr_t>(&arch::boot::TEACHOS_VMA)};
auto mbi_start = frame::containing(mbi_address);
auto mbi_end = frame::containing(mbi_address + mbi_size) + 1;
// TODO BA-FS26: Protect MB2 boot modules
std::ranges::for_each(std::views::iota(mbi_start, mbi_end), [&](auto frame) { new_allocator.mark_used(frame); });
}
} // namespace
auto init() -> void
{
auto static constinit is_initialized = std::atomic_flag{};
if (is_initialized.test_and_set())
{
system::panic("[x86_64] Memory management has already been initialized.");
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