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#include "kapi/memory.hpp"
#include "kapi/system.hpp"
#include "x86_64/boot/boot.hpp"
#include "x86_64/boot/ld.hpp"
#include "x86_64/cpu/registers.hpp"
#include "x86_64/memory/buffered_allocator.hpp"
#include "x86_64/memory/mmu.hpp"
#include "x86_64/memory/page_table.hpp"
#include "x86_64/memory/paging_root.hpp"
#include "x86_64/memory/region_allocator.hpp"
#include "x86_64/memory/scoped_mapping.hpp"
#include <multiboot2/information.hpp>
#include <atomic>
#include <memory>
#include <span>
namespace teachos::memory
{
namespace
{
// NOLINTNEXTLINE(cppcoreguidelines-avoid-non-const-global-variables)
auto constinit allocator = static_cast<frame_allocator *>(nullptr);
constexpr auto static unused_page_address = linear_address{0x0000'7fff'cafe'faceuz};
constexpr auto static recursive_page_map_index = x86_64::page_table::entry_count - 2;
auto create_memory_information() -> x86_64::region_allocator::memory_information
{
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{&boot::x86_64::_start_physical, &boot::x86_64::_end_physical};
return {.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 = mbi->memory_map()};
};
auto create_early_frame_allocator()
{
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.");
}
return x86_64::region_allocator{create_memory_information()};
}
auto enable_cpu_protections() -> void
{
cpu::x86_64::cr0::set(cpu::x86_64::cr0::flags::write_protect);
cpu::x86_64::i32_efer::set(cpu::x86_64::i32_efer::flags::execute_disable_bit_enable);
}
auto inject_faux_pml4(frame_allocator & allocator) -> void
{
using namespace x86_64;
using entry_flags = page_table::entry::flags;
auto temporary_mapper = scoped_mapping{page::containing(unused_page_address), allocator};
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);
paging_root::get()[recursive_page_map_index].frame(new_pml4_frame.value(),
entry_flags::present | entry_flags::writable);
tlb_flush_all();
}
} // namespace
auto active_allocator() -> frame_allocator &
{
if (!allocator)
{
system::panic("[x86_64] The frame allocator has not been set yet.");
}
return *allocator;
}
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.");
}
auto allocator = create_early_frame_allocator();
enable_cpu_protections();
auto allocation_buffer = x86_64::buffered_allocator<4>{&allocator};
inject_faux_pml4(allocation_buffer);
// paging::kernel_mapper kernel(allocator, memory_information);
// kernel.remap_kernel();
// video::vga::text::write("Kernel remapping successful", video::vga::text::common_attributes::green_on_black);
// video::vga::text::newline();
// remap_heap(heap::KERNEL_HEAP_START, heap::KERNEL_HEAP_SIZE);
// video::vga::text::write("Heap remapping successful", video::vga::text::common_attributes::green_on_black);
// video::vga::text::newline();
}
} // namespace teachos::memory
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