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https://github.com/RGBCube/serenity
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65b420f996
These instances were detected by searching for files that include AK/Memory.h, but don't match the regex: \\b(fast_u32_copy|fast_u32_fill|secure_zero|timing_safe_compare)\\b This regex is pessimistic, so there might be more files that don't actually use any memory function. In theory, one might use LibCPP to detect things like this automatically, but let's do this one step after another.
119 lines
4.1 KiB
C++
119 lines
4.1 KiB
C++
/*
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* Copyright (c) 2018-2022, Andreas Kling <kling@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <AK/Singleton.h>
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#include <Kernel/Arch/CPU.h>
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#include <Kernel/Arch/PageDirectory.h>
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#include <Kernel/InterruptDisabler.h>
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#include <Kernel/Memory/MemoryManager.h>
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#include <Kernel/Memory/PageDirectory.h>
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#include <Kernel/Prekernel/Prekernel.h>
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#include <Kernel/Process.h>
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#include <Kernel/Random.h>
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#include <Kernel/Sections.h>
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extern u8 start_of_kernel_image[];
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extern u8 end_of_kernel_image[];
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namespace Kernel::Memory {
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UNMAP_AFTER_INIT NonnullLockRefPtr<PageDirectory> PageDirectory::must_create_kernel_page_directory()
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{
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return adopt_lock_ref_if_nonnull(new (nothrow) PageDirectory).release_nonnull();
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}
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ErrorOr<NonnullLockRefPtr<PageDirectory>> PageDirectory::try_create_for_userspace()
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{
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auto directory = TRY(adopt_nonnull_lock_ref_or_enomem(new (nothrow) PageDirectory));
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#if ARCH(X86_64)
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directory->m_pml4t = TRY(MM.allocate_physical_page());
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#endif
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directory->m_directory_table = TRY(MM.allocate_physical_page());
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auto kernel_pd_index = (kernel_mapping_base >> 30) & 0x1ffu;
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for (size_t i = 0; i < kernel_pd_index; i++) {
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directory->m_directory_pages[i] = TRY(MM.allocate_physical_page());
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}
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// Share the top 1 GiB of kernel-only mappings (>=kernel_mapping_base)
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directory->m_directory_pages[kernel_pd_index] = MM.kernel_page_directory().m_directory_pages[kernel_pd_index];
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#if ARCH(X86_64)
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{
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InterruptDisabler disabler;
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auto& table = *(PageDirectoryPointerTable*)MM.quickmap_page(*directory->m_pml4t);
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table.raw[0] = (FlatPtr)directory->m_directory_table->paddr().as_ptr() | 7;
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MM.unquickmap_page();
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}
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#endif
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{
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InterruptDisabler disabler;
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auto& table = *(PageDirectoryPointerTable*)MM.quickmap_page(*directory->m_directory_table);
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for (size_t i = 0; i < sizeof(m_directory_pages) / sizeof(m_directory_pages[0]); i++) {
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if (directory->m_directory_pages[i]) {
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table.raw[i] = (FlatPtr)directory->m_directory_pages[i]->paddr().as_ptr() | 7;
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}
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}
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#if ARCH(X86_64)
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// 2 ** MAXPHYADDR - 1
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// Where MAXPHYADDR = physical_address_bit_width
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u64 max_physical_address = (1ULL << Processor::current().physical_address_bit_width()) - 1;
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// bit 63 = no execute
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// bit 7 = page size
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// bit 5 = accessed
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// bit 4 = cache disable
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// bit 3 = write through
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// bit 2 = user/supervisor
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// bit 1 = read/write
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// bit 0 = present
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constexpr u64 pdpte_bit_flags = 0x80000000000000BF;
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// This is to notify us of bugs where we're:
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// 1. Going over what the processor is capable of.
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// 2. Writing into the reserved bits (51:MAXPHYADDR), where doing so throws a GPF
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// when writing out the PDPT pointer to CR3.
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// The reason we're not checking the page directory's physical address directly is because
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// we're checking for sign extension when putting it into a PDPTE. See issue #4584.
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for (auto table_entry : table.raw)
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VERIFY((table_entry & ~pdpte_bit_flags) <= max_physical_address);
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#endif
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MM.unquickmap_page();
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}
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register_page_directory(directory);
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return directory;
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}
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PageDirectory::PageDirectory() = default;
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UNMAP_AFTER_INIT void PageDirectory::allocate_kernel_directory()
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{
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// Adopt the page tables already set up by boot.S
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#if ARCH(X86_64)
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dmesgln("MM: boot_pml4t @ {}", boot_pml4t);
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m_pml4t = PhysicalPage::create(boot_pml4t, MayReturnToFreeList::No);
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#endif
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dmesgln("MM: boot_pdpt @ {}", boot_pdpt);
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dmesgln("MM: boot_pd0 @ {}", boot_pd0);
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dmesgln("MM: boot_pd_kernel @ {}", boot_pd_kernel);
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m_directory_table = PhysicalPage::create(boot_pdpt, MayReturnToFreeList::No);
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m_directory_pages[0] = PhysicalPage::create(boot_pd0, MayReturnToFreeList::No);
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m_directory_pages[(kernel_mapping_base >> 30) & 0x1ff] = PhysicalPage::create(boot_pd_kernel, MayReturnToFreeList::No);
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}
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PageDirectory::~PageDirectory()
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{
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if (is_cr3_initialized()) {
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deregister_page_directory(this);
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}
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}
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}
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