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Kernel: Add PML4T support for the PageDirectory class

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This commit is contained in:
Gunnar Beutner 2021-06-26 01:00:40 +02:00 • committed by Andreas Kling
parent f5cd366006
commit 1e20dd2a45
2 changed files with 39 additions and 1 deletions
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28
Kernel/VM/PageDirectory.cpp
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@ -28,6 +28,9 @@ RefPtr<PageDirectory> PageDirectory::find_by_cr3(u32 cr3)
return cr3_map().get(cr3).value_or({});
}
#if ARCH(X86_64)
extern "C" PageDirectoryEntry boot_pml4t[1024];
#endif
extern "C" PageDirectoryEntry* boot_pdpt[4];
extern "C" PageDirectoryEntry boot_pd0[1024];
extern "C" PageDirectoryEntry boot_pd3[1024];
@ -38,6 +41,11 @@ UNMAP_AFTER_INIT PageDirectory::PageDirectory()
m_identity_range_allocator.initialize_with_range(VirtualAddress(FlatPtr(0x00000000)), 0x00200000);
// Adopt the page tables already set up by boot.S
#if ARCH(X86_64)
PhysicalAddress boot_pml4t_paddr(virtual_to_low_physical((FlatPtr)boot_pml4t));
dmesgln("MM: boot_pml4t @ {}", boot_pml4t_paddr);
m_pml4t = PhysicalPage::create(boot_pml4t_paddr, true, false);
#endif
PhysicalAddress boot_pdpt_paddr(virtual_to_low_physical((FlatPtr)boot_pdpt));
PhysicalAddress boot_pd0_paddr(virtual_to_low_physical((FlatPtr)boot_pd0));
PhysicalAddress boot_pd3_paddr(virtual_to_low_physical((FlatPtr)boot_pd3));
@ -64,6 +72,11 @@ PageDirectory::PageDirectory(const RangeAllocator* parent_range_allocator)
}
// Set up a userspace page directory
#if ARCH(X86_64)
m_pml4t = MM.allocate_user_physical_page();
if (!m_pml4t)
return;
#endif
m_directory_table = MM.allocate_user_physical_page();
if (!m_directory_table)
return;
@ -79,12 +92,27 @@ PageDirectory::PageDirectory(const RangeAllocator* parent_range_allocator)
// Share the top 1 GiB of kernel-only mappings (>=3GiB or >=0xc0000000)
m_directory_pages[3] = MM.kernel_page_directory().m_directory_pages[3];
#if ARCH(X86_64)
{
auto& table = *(PageDirectoryPointerTable*)MM.quickmap_page(*m_pml4t);
table.raw[0] = (FlatPtr)m_directory_table->paddr().as_ptr() | 3;
MM.unquickmap_page();
}
#endif
{
auto& table = *(PageDirectoryPointerTable*)MM.quickmap_page(*m_directory_table);
#if ARCH(I386)
table.raw[0] = (FlatPtr)m_directory_pages[0]->paddr().as_ptr() | 1;
table.raw[1] = (FlatPtr)m_directory_pages[1]->paddr().as_ptr() | 1;
table.raw[2] = (FlatPtr)m_directory_pages[2]->paddr().as_ptr() | 1;
table.raw[3] = (FlatPtr)m_directory_pages[3]->paddr().as_ptr() | 1;
#else
table.raw[0] = (FlatPtr)m_directory_pages[0]->paddr().as_ptr() | 3;
table.raw[1] = (FlatPtr)m_directory_pages[1]->paddr().as_ptr() | 3;
table.raw[2] = (FlatPtr)m_directory_pages[2]->paddr().as_ptr() | 3;
table.raw[3] = (FlatPtr)m_directory_pages[3]->paddr().as_ptr() | 3;
#endif
// 2 ** MAXPHYADDR - 1
// Where MAXPHYADDR = physical_address_bit_width