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Kernel/aarch64: Set up pointer to kernel page directory

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The MemoryManager uses this pointer to adds its newly created page
tables to the kernel page directory.
This commit is contained in:
Timon Kruiper 2022-09-21 16:46:06 +02:00 • committed by Andreas Kling
parent 96f73c9289
commit c2e410195a
2 changed files with 26 additions and 3 deletions
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25
Kernel/Arch/aarch64/MMU.cpp
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@ -188,6 +188,30 @@ static void activate_mmu()
Aarch64::Asm::flush();
}
static u64* get_page_directory(u64* root_table, VirtualAddress virtual_addr)
{
u64 level0_idx = (virtual_addr.get() >> 39) & 0x1FF;
u64 level1_idx = (virtual_addr.get() >> 30) & 0x1FF;
u64* level1_table = root_table;
if (level1_table[level0_idx] == 0)
return nullptr;
u64* level2_table = descriptor_to_pointer(level1_table[level0_idx]);
if (level2_table[level1_idx] == 0)
return nullptr;
return descriptor_to_pointer(level2_table[level1_idx]);
}
static void setup_kernel_page_directory(u64* root_table)
{
boot_pd_kernel = PhysicalAddress((PhysicalPtr)get_page_directory(root_table, VirtualAddress { kernel_mapping_base }));
VERIFY(!boot_pd_kernel.is_null());
}
void init_page_tables()
{
// We currently identity map the physical memory, so the offset is 0.
@ -198,6 +222,7 @@ void init_page_tables()
auto root_table = allocator.take_page();
build_identity_map(allocator, root_table);
setup_quickmap_page_table(allocator, root_table);
setup_kernel_page_directory(root_table);
switch_to_page_table(page_tables_phys_start);
activate_mmu();