547 lines
14 KiB
C++
547 lines
14 KiB
C++
#include <BAN/Errors.h>
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#include <kernel/Arch.h>
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#include <kernel/CPUID.h>
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#include <kernel/LockGuard.h>
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#include <kernel/Memory/kmalloc.h>
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#include <kernel/Memory/PageTable.h>
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extern uint8_t g_kernel_start[];
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extern uint8_t g_kernel_end[];
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extern uint8_t g_kernel_execute_start[];
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extern uint8_t g_kernel_execute_end[];
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extern uint8_t g_userspace_start[];
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extern uint8_t g_userspace_end[];
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namespace Kernel
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{
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static PageTable* s_kernel = nullptr;
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static PageTable* s_current = nullptr;
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static bool s_has_nxe = false;
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static bool s_has_pge = false;
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// PML4 entry for kernel memory
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static paddr_t s_global_pml4e = 0;
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static constexpr inline bool is_canonical(uintptr_t addr)
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{
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constexpr uintptr_t mask = 0xFFFF800000000000;
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addr &= mask;
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return addr == mask || addr == 0;
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}
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static constexpr inline uintptr_t uncanonicalize(uintptr_t addr)
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{
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if (addr & 0x0000800000000000)
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return addr & ~0xFFFF000000000000;
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return addr;
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}
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static constexpr inline uintptr_t canonicalize(uintptr_t addr)
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{
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if (addr & 0x0000800000000000)
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return addr | 0xFFFF000000000000;
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return addr;
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}
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static inline PageTable::flags_t parse_flags(uint64_t entry)
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{
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return (s_has_nxe && !(entry & (1ull << 63)) ? PageTable::Flags::Execute : 0) | (entry & 0b100000111);
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}
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void PageTable::initialize()
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{
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if (CPUID::has_nxe())
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{
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asm volatile(
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"movl $0xC0000080, %ecx;"
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"rdmsr;"
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"orl $0x800, %eax;"
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"wrmsr"
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);
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s_has_nxe = true;
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}
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uint32_t ecx, edx;
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CPUID::get_features(ecx, edx);
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if (edx & CPUID::EDX_PGE)
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{
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asm volatile(
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"movq %cr4, %rax;"
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"orq $0x80, %rax;"
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"movq %rax, %cr4;"
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);
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s_has_pge = true;
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}
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ASSERT(s_kernel == nullptr);
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s_kernel = new PageTable();
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ASSERT(s_kernel);
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s_kernel->initialize_kernel();
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s_kernel->load();
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}
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PageTable& PageTable::kernel()
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{
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ASSERT(s_kernel);
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return *s_kernel;
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}
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PageTable& PageTable::current()
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{
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ASSERT(s_current);
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return *s_current;
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}
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static uint64_t* allocate_zeroed_page_aligned_page()
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{
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void* page = kmalloc(PAGE_SIZE, PAGE_SIZE, true);
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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 PageTable::initialize_kernel()
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{
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ASSERT(s_global_pml4e == 0);
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s_global_pml4e = V2P(allocate_zeroed_page_aligned_page());
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m_highest_paging_struct = V2P(allocate_zeroed_page_aligned_page());
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uint64_t* pml4 = (uint64_t*)P2V(m_highest_paging_struct);
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pml4[511] = s_global_pml4e;
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// Map (0 -> phys_kernel_end) to (KERNEL_OFFSET -> virt_kernel_end)
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map_range_at(0, KERNEL_OFFSET, (uintptr_t)g_kernel_end - KERNEL_OFFSET, Flags::ReadWrite | Flags::Present);
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// Map executable kernel memory as executable
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map_range_at(
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V2P(g_kernel_execute_start),
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(vaddr_t)g_kernel_execute_start,
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g_kernel_execute_end - g_kernel_execute_start,
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Flags::Execute | Flags::Present
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);
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// Map userspace memory
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map_range_at(
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V2P(g_userspace_start),
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(vaddr_t)g_userspace_start,
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g_userspace_end - g_userspace_start,
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Flags::Execute | Flags::UserSupervisor | Flags::Present
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);
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}
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BAN::ErrorOr<PageTable*> PageTable::create_userspace()
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{
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LockGuard _(s_kernel->m_lock);
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PageTable* page_table = new PageTable;
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if (page_table == nullptr)
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return BAN::Error::from_errno(ENOMEM);
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page_table->map_kernel_memory();
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return page_table;
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}
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void PageTable::map_kernel_memory()
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{
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ASSERT(s_kernel);
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ASSERT(s_global_pml4e);
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ASSERT(m_highest_paging_struct == 0);
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m_highest_paging_struct = V2P(allocate_zeroed_page_aligned_page());
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uint64_t* kernel_pml4 = (uint64_t*)P2V(s_kernel->m_highest_paging_struct);
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uint64_t* pml4 = (uint64_t*)P2V(m_highest_paging_struct);
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pml4[511] = kernel_pml4[511];
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}
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PageTable::~PageTable()
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{
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uint64_t* pml4 = (uint64_t*)P2V(m_highest_paging_struct);
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// NOTE: we only loop until 511 since the last one is the kernel memory
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for (uint64_t pml4e = 0; pml4e < 511; 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*)P2V(pml4[pml4e] & PAGE_ADDR_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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uint64_t* pd = (uint64_t*)P2V(pdpt[pdpte] & PAGE_ADDR_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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kfree((void*)P2V(pd[pde] & PAGE_ADDR_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 PageTable::load()
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{
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asm volatile("movq %0, %%cr3" :: "r"(m_highest_paging_struct));
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s_current = this;
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}
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void PageTable::invalidate(vaddr_t vaddr)
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{
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if (this == s_current)
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asm volatile("invlpg (%0)" :: "r"(vaddr) : "memory");
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}
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void PageTable::unmap_page(vaddr_t vaddr)
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{
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LockGuard _(m_lock);
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vaddr &= PAGE_ADDR_MASK;
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if (vaddr && (vaddr >= KERNEL_OFFSET) != (this == s_kernel))
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Kernel::panic("unmapping {8H}, kernel: {}", vaddr, this == s_kernel);
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if (is_page_free(vaddr))
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{
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dwarnln("unmapping unmapped page {8H}", vaddr);
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return;
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}
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ASSERT(is_canonical(vaddr));
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vaddr = uncanonicalize(vaddr);
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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 = (uint64_t*)P2V(m_highest_paging_struct);
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uint64_t* pdpt = (uint64_t*)P2V(pml4[pml4e] & PAGE_ADDR_MASK);
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uint64_t* pd = (uint64_t*)P2V(pdpt[pdpte] & PAGE_ADDR_MASK);
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uint64_t* pt = (uint64_t*)P2V(pd[pde] & PAGE_ADDR_MASK);
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pt[pte] = 0;
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invalidate(canonicalize(vaddr));
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}
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void PageTable::unmap_range(vaddr_t vaddr, size_t size)
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{
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LockGuard _(m_lock);
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vaddr_t s_page = vaddr / PAGE_SIZE;
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vaddr_t e_page = (vaddr + size - 1) / PAGE_SIZE;
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for (vaddr_t page = s_page; page <= e_page; page++)
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unmap_page(page * PAGE_SIZE);
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}
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void PageTable::map_page_at(paddr_t paddr, vaddr_t vaddr, flags_t flags)
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{
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LockGuard _(m_lock);
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if (vaddr && (vaddr >= KERNEL_OFFSET) != (this == s_kernel))
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Kernel::panic("mapping {8H} to {8H}, kernel: {}", paddr, vaddr, this == s_kernel);
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ASSERT(is_canonical(vaddr));
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vaddr = uncanonicalize(vaddr);
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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::Used);
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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 extra_flags = 0;
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if (s_has_nxe && !(flags & Flags::Execute))
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extra_flags |= 1ull << 63;
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if (s_has_pge && pml4e == 511)
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extra_flags |= 1ull << 8;
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if (flags & Flags::Reserved)
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extra_flags |= Flags::Reserved;
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flags_t uwr_flags = flags & 0b111;
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uint64_t* pml4 = (uint64_t*)P2V(m_highest_paging_struct);
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if ((pml4[pml4e] & uwr_flags) != uwr_flags)
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{
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if (!(pml4[pml4e] & Flags::Present))
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pml4[pml4e] = V2P(allocate_zeroed_page_aligned_page());
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pml4[pml4e] |= uwr_flags;
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}
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uint64_t* pdpt = (uint64_t*)P2V(pml4[pml4e] & PAGE_ADDR_MASK);
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if ((pdpt[pdpte] & uwr_flags) != uwr_flags)
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{
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if (!(pdpt[pdpte] & Flags::Present))
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pdpt[pdpte] = V2P(allocate_zeroed_page_aligned_page());
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pdpt[pdpte] |= uwr_flags;
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}
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uint64_t* pd = (uint64_t*)P2V(pdpt[pdpte] & PAGE_ADDR_MASK);
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if ((pd[pde] & uwr_flags) != uwr_flags)
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{
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if (!(pd[pde] & Flags::Present))
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pd[pde] = V2P(allocate_zeroed_page_aligned_page());
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pd[pde] |= uwr_flags;
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}
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uint64_t* pt = (uint64_t*)P2V(pd[pde] & PAGE_ADDR_MASK);
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pt[pte] = paddr | uwr_flags | extra_flags;
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invalidate(canonicalize(vaddr));
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}
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void PageTable::map_range_at(paddr_t paddr, vaddr_t vaddr, size_t size, flags_t flags)
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{
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LockGuard _(m_lock);
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ASSERT(is_canonical(vaddr));
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ASSERT(paddr % PAGE_SIZE == 0);
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ASSERT(vaddr % PAGE_SIZE == 0);
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size_t first_page = vaddr / PAGE_SIZE;
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size_t last_page = (vaddr + size - 1) / PAGE_SIZE;
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size_t page_count = last_page - first_page + 1;
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for (size_t page = 0; page < page_count; page++)
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map_page_at(paddr + page * PAGE_SIZE, vaddr + page * PAGE_SIZE, flags);
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}
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uint64_t PageTable::get_page_data(vaddr_t vaddr) const
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{
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LockGuard _(m_lock);
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ASSERT(is_canonical(vaddr));
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vaddr = uncanonicalize(vaddr);
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ASSERT(vaddr % PAGE_SIZE == 0);
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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 = (uint64_t*)P2V(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*)P2V(pml4[pml4e] & PAGE_ADDR_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*)P2V(pdpt[pdpte] & PAGE_ADDR_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*)P2V(pd[pde] & PAGE_ADDR_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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PageTable::flags_t PageTable::get_page_flags(vaddr_t addr) const
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{
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return parse_flags(get_page_data(addr));
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}
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paddr_t PageTable::physical_address_of(vaddr_t addr) const
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{
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uint64_t page_data = get_page_data(addr);
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return (page_data & PAGE_ADDR_MASK) & ~(1ull << 63);
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}
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vaddr_t PageTable::get_free_page(vaddr_t first_address)
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{
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LockGuard _(m_lock);
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if (size_t rem = first_address % PAGE_SIZE)
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first_address += PAGE_SIZE - rem;
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ASSERT(is_canonical(first_address));
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vaddr_t vaddr = uncanonicalize(first_address);
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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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// Try to find free page that can be mapped without
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// allocations (page table with unused entries)
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uint64_t* pml4 = (uint64_t*)P2V(m_highest_paging_struct);
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for (; 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*)P2V(pml4[pml4e] & PAGE_ADDR_MASK);
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for (; 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*)P2V(pdpt[pdpte] & PAGE_ADDR_MASK);
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for (; 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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uint64_t* pt = (uint64_t*)P2V(pd[pde] & PAGE_ADDR_MASK);
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for (; pte < 512; pte++)
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{
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if (!(pt[pte] & Flags::Used))
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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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pt[pte] |= Flags::Reserved;
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return canonicalize(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
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vaddr = first_address;
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while (is_canonical(vaddr))
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{
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if (is_page_free(vaddr))
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{
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map_page_at(0, vaddr, Flags::Reserved);
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return vaddr;
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}
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if (vaddr > vaddr + PAGE_SIZE)
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break;
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vaddr += PAGE_SIZE;
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}
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ASSERT_NOT_REACHED();
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}
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vaddr_t PageTable::get_free_contiguous_pages(size_t page_count, vaddr_t first_address)
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{
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if (first_address % PAGE_SIZE)
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first_address = (first_address + PAGE_SIZE - 1) & PAGE_ADDR_MASK;
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LockGuard _(m_lock);
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for (vaddr_t vaddr = first_address; is_canonical(vaddr); vaddr += PAGE_SIZE)
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{
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bool valid { true };
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for (size_t page = 0; page < page_count; page++)
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{
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if (get_page_flags(vaddr + page * PAGE_SIZE) & Flags::Used)
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{
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vaddr += page * PAGE_SIZE;
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valid = false;
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break;
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}
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}
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if (valid)
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{
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for (size_t page = 0; page < page_count; page++)
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map_page_at(0, vaddr + page * PAGE_SIZE, Flags::Reserved);
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return vaddr;
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}
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}
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ASSERT_NOT_REACHED();
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}
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bool PageTable::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::Used);
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}
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bool PageTable::is_range_free(vaddr_t start, size_t size) const
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{
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LockGuard _(m_lock);
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vaddr_t first_page = start / PAGE_SIZE;
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vaddr_t last_page = (start + size - 1) / 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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static void dump_range(vaddr_t start, vaddr_t end, PageTable::flags_t flags)
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{
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if (start == 0)
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return;
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dprintln("{}-{}: {}{}{}{}",
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(void*)canonicalize(start),
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(void*)canonicalize(end - 1),
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flags & PageTable::Flags::Execute ? 'x' : '-',
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flags & PageTable::Flags::UserSupervisor ? 'u' : '-',
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flags & PageTable::Flags::ReadWrite ? 'w' : '-',
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flags & PageTable::Flags::Present ? 'r' : '-'
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);
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}
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void PageTable::debug_dump()
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{
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LockGuard _(m_lock);
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flags_t flags = 0;
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vaddr_t start = 0;
|
|
|
|
uint64_t* pml4 = (uint64_t*)P2V(m_highest_paging_struct);
|
|
for (uint64_t pml4e = 0; pml4e < 512; pml4e++)
|
|
{
|
|
if (!(pml4[pml4e] & Flags::Present))
|
|
{
|
|
dump_range(start, (pml4e << 39), flags);
|
|
start = 0;
|
|
continue;
|
|
}
|
|
uint64_t* pdpt = (uint64_t*)P2V(pml4[pml4e] & PAGE_ADDR_MASK);
|
|
for (uint64_t pdpte = 0; pdpte < 512; pdpte++)
|
|
{
|
|
if (!(pdpt[pdpte] & Flags::Present))
|
|
{
|
|
dump_range(start, (pml4e << 39) | (pdpte << 30), flags);
|
|
start = 0;
|
|
continue;
|
|
}
|
|
uint64_t* pd = (uint64_t*)P2V(pdpt[pdpte] & PAGE_ADDR_MASK);
|
|
for (uint64_t pde = 0; pde < 512; pde++)
|
|
{
|
|
if (!(pd[pde] & Flags::Present))
|
|
{
|
|
dump_range(start, (pml4e << 39) | (pdpte << 30) | (pde << 21), flags);
|
|
start = 0;
|
|
continue;
|
|
}
|
|
uint64_t* pt = (uint64_t*)P2V(pd[pde] & PAGE_ADDR_MASK);
|
|
for (uint64_t pte = 0; pte < 512; pte++)
|
|
{
|
|
if (parse_flags(pt[pte]) != flags)
|
|
{
|
|
dump_range(start, (pml4e << 39) | (pdpte << 30) | (pde << 21) | (pte << 12), flags);
|
|
start = 0;
|
|
}
|
|
|
|
if (!(pt[pte] & Flags::Used))
|
|
continue;
|
|
|
|
if (start == 0)
|
|
{
|
|
flags = parse_flags(pt[pte]);
|
|
start = (pml4e << 39) | (pdpte << 30) | (pde << 21) | (pte << 12);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
}
|