342 lines
8.3 KiB
C++
342 lines
8.3 KiB
C++
#include <BAN/Errors.h>
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#include <kernel/Memory/kmalloc.h>
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#include <kernel/Memory/MMU.h>
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#define FLAGS_MASK (PAGE_SIZE - 1)
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#define PAGE_MASK (~FLAGS_MASK)
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#define CLEANUP_STRUCTURE(s) \
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for (uint64_t i = 0; i < 512; i++) \
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if (s[i] & Flags::Present) \
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return; \
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kfree(s)
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extern uint8_t g_kernel_end[];
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namespace Kernel
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{
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static MMU* s_instance = nullptr;
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void MMU::initialize()
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{
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ASSERT(s_instance == nullptr);
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s_instance = new MMU();
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ASSERT(s_instance);
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s_instance->initialize_kernel();
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s_instance->load();
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}
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MMU& MMU::get()
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{
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ASSERT(s_instance);
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return *s_instance;
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}
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static uint64_t* allocate_page_aligned_page()
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{
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void* page = kmalloc(PAGE_SIZE, PAGE_SIZE);
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ASSERT(page);
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memset(page, 0, PAGE_SIZE);
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return (uint64_t*)page;
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}
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void MMU::initialize_kernel()
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{
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m_highest_paging_struct = allocate_page_aligned_page();
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memset(m_highest_paging_struct, 0, PAGE_SIZE);
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// Identity map 4 KiB -> kernel end. We don't map the first page since nullptr derefs should
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// page fault. Also there isn't anything useful in that memory.
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identity_map_range(PAGE_SIZE, (uintptr_t)g_kernel_end, Flags::ReadWrite | Flags::Present);
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}
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MMU::MMU()
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{
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if (s_instance == nullptr)
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return;
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// Here we copy the s_instances paging structs since they are
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// global for every process
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uint64_t* global_pml4 = s_instance->m_highest_paging_struct;
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uint64_t* pml4 = allocate_page_aligned_page();
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for (uint32_t pml4e = 0; pml4e < 512; pml4e++)
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{
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if (!(global_pml4[pml4e] & Flags::Present))
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continue;
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uint64_t* global_pdpt = (uint64_t*)(global_pml4[pml4e] & PAGE_MASK);
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uint64_t* pdpt = allocate_page_aligned_page();
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pml4[pml4e] = (uint64_t)pdpt | (global_pml4[pml4e] & FLAGS_MASK);
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for (uint32_t pdpte = 0; pdpte < 512; pdpte++)
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{
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if (!(global_pdpt[pdpte] & Flags::Present))
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continue;
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uint64_t* global_pd = (uint64_t*)(global_pdpt[pdpte] & PAGE_MASK);
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uint64_t* pd = allocate_page_aligned_page();
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pdpt[pdpte] = (uint64_t)pd | (global_pdpt[pdpte] & FLAGS_MASK);
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for (uint32_t pde = 0; pde < 512; pde++)
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{
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if (!(global_pd[pde] & Flags::Present))
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continue;
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uint64_t* global_pt = (uint64_t*)(global_pd[pde] & PAGE_MASK);
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uint64_t* pt = allocate_page_aligned_page();
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pd[pde] = (uint64_t)pt | (global_pd[pde] & FLAGS_MASK);
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memcpy(pt, global_pt, PAGE_SIZE);
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}
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}
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}
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m_highest_paging_struct = pml4;
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}
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MMU::~MMU()
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{
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uint64_t* pml4 = m_highest_paging_struct;
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for (uint32_t pml4e = 0; pml4e < 512; pml4e++)
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{
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if (!(pml4[pml4e] & Flags::Present))
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continue;
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uint64_t* pdpt = (uint64_t*)(pml4[pml4e] & PAGE_MASK);
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for (uint32_t pdpte = 0; pdpte < 512; pdpte++)
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{
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if (!(pdpt[pdpte] & Flags::Present))
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continue;
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uint64_t* pd = (uint64_t*)(pdpt[pdpte] & PAGE_MASK);
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for (uint32_t pde = 0; pde < 512; pde++)
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{
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if (!(pd[pde] & Flags::Present))
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continue;
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kfree((void*)(pd[pde] & PAGE_MASK));
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}
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kfree(pd);
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}
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kfree(pdpt);
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}
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kfree(pml4);
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}
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void MMU::load()
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{
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asm volatile("movq %0, %%cr3" :: "r"(m_highest_paging_struct));
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}
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void MMU::identity_map_page(paddr_t address, flags_t flags)
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{
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address &= PAGE_MASK;
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map_page_at(address, address, flags);
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}
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void MMU::identity_map_range(paddr_t address, size_t size, flags_t flags)
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{
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paddr_t s_page = address & PAGE_MASK;
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paddr_t e_page = (address + size - 1) & PAGE_MASK;
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for (paddr_t page = s_page; page <= e_page; page += PAGE_SIZE)
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identity_map_page(page, flags);
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}
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void MMU::unmap_page(vaddr_t address)
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{
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ASSERT((address >> 48) == 0);
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address &= PAGE_MASK;
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uint64_t pml4e = (address >> 39) & 0x1FF;
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uint64_t pdpte = (address >> 30) & 0x1FF;
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uint64_t pde = (address >> 21) & 0x1FF;
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uint64_t pte = (address >> 12) & 0x1FF;
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uint64_t* pml4 = m_highest_paging_struct;
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if (!(pml4[pml4e] & Flags::Present))
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return;
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uint64_t* pdpt = (uint64_t*)(pml4[pml4e] & PAGE_MASK);
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if (!(pdpt[pdpte] & Flags::Present))
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return;
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uint64_t* pd = (uint64_t*)(pdpt[pdpte] & PAGE_MASK);
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if (!(pd[pde] & Flags::Present))
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return;
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uint64_t* pt = (uint64_t*)(pd[pde] & PAGE_MASK);
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if (!(pt[pte] & Flags::Present))
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return;
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pt[pte] = 0;
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CLEANUP_STRUCTURE(pt);
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pd[pde] = 0;
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CLEANUP_STRUCTURE(pd);
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pdpt[pdpte] = 0;
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CLEANUP_STRUCTURE(pdpt);
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pml4[pml4e] = 0;
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}
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void MMU::unmap_range(vaddr_t address, size_t size)
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{
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vaddr_t s_page = address & PAGE_MASK;
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vaddr_t e_page = (address + size - 1) & PAGE_MASK;
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for (vaddr_t page = s_page; page <= e_page; page += PAGE_SIZE)
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unmap_page(page);
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}
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void MMU::map_page_at(paddr_t paddr, vaddr_t vaddr, flags_t flags)
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{
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ASSERT((paddr >> 48) == 0);
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ASSERT((vaddr >> 48) == 0);
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ASSERT(paddr % PAGE_SIZE == 0);
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ASSERT(vaddr % PAGE_SIZE == 0);;
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ASSERT(flags & Flags::Present);
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uint64_t pml4e = (vaddr >> 39) & 0x1FF;
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uint64_t pdpte = (vaddr >> 30) & 0x1FF;
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uint64_t pde = (vaddr >> 21) & 0x1FF;
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uint64_t pte = (vaddr >> 12) & 0x1FF;
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uint64_t* pml4 = m_highest_paging_struct;
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if ((pml4[pml4e] & flags) != flags)
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{
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if (!(pml4[pml4e] & Flags::Present))
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pml4[pml4e] = (uint64_t)allocate_page_aligned_page();
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pml4[pml4e] = (pml4[pml4e] & PAGE_MASK) | flags;
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}
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uint64_t* pdpt = (uint64_t*)(pml4[pml4e] & PAGE_MASK);
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if ((pdpt[pdpte] & flags) != flags)
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{
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if (!(pdpt[pdpte] & Flags::Present))
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pdpt[pdpte] = (uint64_t)allocate_page_aligned_page();
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pdpt[pdpte] = (pdpt[pdpte] & PAGE_MASK) | flags;
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}
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uint64_t* pd = (uint64_t*)(pdpt[pdpte] & PAGE_MASK);
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if ((pd[pde] & flags) != flags)
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{
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if (!(pd[pde] & Flags::Present))
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pd[pde] = (uint64_t)allocate_page_aligned_page();
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pd[pde] = (pd[pde] & PAGE_MASK) | flags;
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}
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uint64_t* pt = (uint64_t*)(pd[pde] & PAGE_MASK);
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if ((pt[pte] & flags) != flags)
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pt[pte] = paddr | flags;
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}
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uint64_t MMU::get_page_data(vaddr_t address) const
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{
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ASSERT((address >> 48) == 0);
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ASSERT(address % PAGE_SIZE == 0);
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uint64_t pml4e = (address >> 39) & 0x1FF;
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uint64_t pdpte = (address >> 30) & 0x1FF;
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uint64_t pde = (address >> 21) & 0x1FF;
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uint64_t pte = (address >> 12) & 0x1FF;
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uint64_t* pml4 = m_highest_paging_struct;
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if (!(pml4[pml4e] & Flags::Present))
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return 0;
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uint64_t* pdpt = (uint64_t*)(pml4[pml4e] & PAGE_MASK);
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if (!(pdpt[pdpte] & Flags::Present))
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return 0;
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uint64_t* pd = (uint64_t*)(pdpt[pdpte] & PAGE_MASK);
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if (!(pd[pde] & Flags::Present))
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return 0;
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uint64_t* pt = (uint64_t*)(pd[pde] & PAGE_MASK);
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if (!(pt[pte] & Flags::Present))
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return 0;
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return pt[pte];
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}
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MMU::flags_t MMU::get_page_flags(vaddr_t addr) const
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{
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return get_page_data(addr) & FLAGS_MASK;
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}
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paddr_t MMU::physical_address_of(vaddr_t addr) const
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{
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return get_page_data(addr) & PAGE_MASK;
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}
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vaddr_t MMU::get_free_page() const
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{
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// Try to find free page that can be mapped without
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// allocations (page table with unused entries)
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vaddr_t* pml4 = m_highest_paging_struct;
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for (uint64_t pml4e = 0; pml4e < 512; pml4e++)
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{
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if (!(pml4[pml4e] & Flags::Present))
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continue;
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vaddr_t* pdpt = (vaddr_t*)(pml4[pml4e] & PAGE_MASK);
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for (uint64_t pdpte = 0; pdpte < 512; pdpte++)
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{
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if (!(pdpt[pdpte] & Flags::Present))
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continue;
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vaddr_t* pd = (vaddr_t*)(pdpt[pdpte] & PAGE_MASK);
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for (uint64_t pde = 0; pde < 512; pde++)
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{
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if (!(pd[pde] & Flags::Present))
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continue;
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vaddr_t* pt = (vaddr_t*)(pd[pde] & PAGE_MASK);
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for (uint64_t pte = !(pml4e + pdpte + pde); pte < 512; pte++)
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{
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if (!(pt[pte] & Flags::Present))
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{
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vaddr_t vaddr = 0;
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vaddr |= pml4e << 39;
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vaddr |= pdpte << 30;
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vaddr |= pde << 21;
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vaddr |= pte << 12;
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return vaddr;
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}
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}
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}
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}
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}
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// Find any free page page (except for page 0)
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vaddr_t address = PAGE_SIZE;
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while ((address << 48) == 0)
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{
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if (!(get_page_flags(address) & Flags::Present))
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return address;
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address += PAGE_SIZE;
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}
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ASSERT_NOT_REACHED();
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}
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bool MMU::is_page_free(vaddr_t page) const
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{
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ASSERT(page % PAGE_SIZE == 0);
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return !(get_page_flags(page) & Flags::Present);
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}
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bool MMU::is_range_free(vaddr_t start, size_t size) const
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{
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vaddr_t first_page = start / PAGE_SIZE;
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vaddr_t last_page = BAN::Math::div_round_up<vaddr_t>(start + size, PAGE_SIZE);
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for (vaddr_t page = first_page; page <= last_page; page++)
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if (!is_page_free(page * PAGE_SIZE))
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return false;
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return true;
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}
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}
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