285 lines
6.9 KiB
C++
285 lines
6.9 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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// FIXME: We should just identity map until g_kernel_end
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ASSERT((uintptr_t)g_kernel_end <= 6 * (1 << 20));
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// Identity map from 0 -> 6 MiB
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m_highest_paging_struct = allocate_page_aligned_page();
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uint64_t* pdpt = allocate_page_aligned_page();
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m_highest_paging_struct[0] = (uint64_t)pdpt | Flags::ReadWrite | Flags::Present;
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uint64_t* pd = allocate_page_aligned_page();
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pdpt[0] = (uint64_t)pd | Flags::ReadWrite | Flags::Present;
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for (uint32_t i = 0; i < 3; i++)
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{
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uint64_t* pt = allocate_page_aligned_page();
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for (uint64_t j = 0; j < 512; j++)
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pt[j] = (i << 21) | (j << 12) | Flags::ReadWrite | Flags::Present;
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pd[i] = (uint64_t)pt | Flags::ReadWrite | Flags::Present;
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}
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// Unmap 0 -> 4 KiB
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uint64_t* pt1 = (uint64_t*)(pd[0] & PAGE_MASK);
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pt1[0] = 0;
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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, uint8_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, ptrdiff_t size, uint8_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, ptrdiff_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, uint8_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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uint8_t MMU::get_page_flags(vaddr_t address) const
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{
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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] & FLAGS_MASK;
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}
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}
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