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Kernel/aarch64: Map kernel and MMIO in high virtual memory

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In the upcoming commits, we'll change the kernel to run at a virtual
address in high memory. This commit prepares for that by making sure the
kernel and mmio are mapped into high virtual memory.
This commit is contained in:
Timon Kruiper 2023-01-07 11:49:14 +01:00 • committed by Linus Groh
parent 33581d5c44
commit 69c49b3d00
1 changed files with 24 additions and 11 deletions
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35
Kernel/Arch/aarch64/MMU.cpp
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@ -112,16 +112,19 @@ static u64* insert_page_table(PageBumpAllocator& allocator, u64* page_table, Vir
return descriptor_to_pointer(level3_table[level2_idx]);
}
static void insert_identity_entries_for_physical_memory_range(PageBumpAllocator& allocator, u64* page_table, FlatPtr start, FlatPtr end, u64 flags)
static void insert_entries_for_memory_range(PageBumpAllocator& allocator, u64* page_table, VirtualAddress start, VirtualAddress end, PhysicalAddress paddr, u64 flags)
{
// Not very efficient, but simple and it works.
for (FlatPtr addr = start; addr < end; addr += GRANULE_SIZE) {
u64* level4_table = insert_page_table(allocator, page_table, VirtualAddress { addr });
for (VirtualAddress addr = start; addr < end;) {
u64* level4_table = insert_page_table(allocator, page_table, addr);
u64 level3_idx = (addr >> 12) & 0x1FF;
u64 level3_idx = (addr.get() >> 12) & 0x1FF;
u64* l4_entry = &level4_table[level3_idx];
*l4_entry = addr;
*l4_entry = paddr.get();
*l4_entry |= flags;
addr = addr.offset(GRANULE_SIZE);
paddr = paddr.offset(GRANULE_SIZE);
}
}
@ -132,17 +135,27 @@ static void setup_quickmap_page_table(PageBumpAllocator& allocator, u64* root_ta
boot_pd_kernel_pt1023 = (PageTableEntry*)insert_page_table(allocator, root_table, VirtualAddress { KERNEL_PT1024_BASE });
}
static void build_identity_map(PageBumpAllocator& allocator, u64* root_table)
static void build_mappings(PageBumpAllocator& allocator, u64* root_table)
{
u64 normal_memory_flags = ACCESS_FLAG | PAGE_DESCRIPTOR | INNER_SHAREABLE | NORMAL_MEMORY;
u64 device_memory_flags = ACCESS_FLAG | PAGE_DESCRIPTOR | OUTER_SHAREABLE | DEVICE_MEMORY;
// Align the identity mapping of the kernel image to 2 MiB, the rest of the memory is initially not mapped.
FlatPtr start_of_range = ((FlatPtr)start_of_kernel_image & ~(FlatPtr)0x1fffff);
FlatPtr end_of_range = ((FlatPtr)end_of_kernel_image & ~(FlatPtr)0x1fffff) + 0x200000 - 1;
auto start_of_kernel_range = VirtualAddress(((FlatPtr)start_of_kernel_image + KERNEL_MAPPING_BASE) & ~(FlatPtr)0x1fffff);
auto end_of_kernel_range = VirtualAddress((((FlatPtr)end_of_kernel_image + KERNEL_MAPPING_BASE) & ~(FlatPtr)0x1fffff) + 0x200000 - 1);
auto start_of_mmio_range = VirtualAddress(RPi::MMIO::the().peripheral_base_address() + KERNEL_MAPPING_BASE);
auto end_of_mmio_range = VirtualAddress(RPi::MMIO::the().peripheral_end_address() + KERNEL_MAPPING_BASE);
insert_identity_entries_for_physical_memory_range(allocator, root_table, start_of_range, end_of_range, normal_memory_flags);
insert_identity_entries_for_physical_memory_range(allocator, root_table, RPi::MMIO::the().peripheral_base_address(), RPi::MMIO::the().peripheral_end_address(), device_memory_flags);
auto start_of_physical_kernel_range = PhysicalAddress(start_of_kernel_range.get()).offset(-KERNEL_MAPPING_BASE);
auto start_of_physical_mmio_range = PhysicalAddress(start_of_mmio_range.get()).offset(-KERNEL_MAPPING_BASE);
// Insert identity mappings
insert_entries_for_memory_range(allocator, root_table, start_of_kernel_range.offset(-KERNEL_MAPPING_BASE), end_of_kernel_range.offset(-KERNEL_MAPPING_BASE), start_of_physical_kernel_range, normal_memory_flags);
insert_entries_for_memory_range(allocator, root_table, start_of_mmio_range.offset(-KERNEL_MAPPING_BASE), end_of_mmio_range.offset(-KERNEL_MAPPING_BASE), start_of_physical_mmio_range, device_memory_flags);
// Map kernel and MMIO into high virtual memory
insert_entries_for_memory_range(allocator, root_table, start_of_kernel_range, end_of_kernel_range, start_of_physical_kernel_range, normal_memory_flags);
insert_entries_for_memory_range(allocator, root_table, start_of_mmio_range, end_of_mmio_range, start_of_physical_mmio_range, device_memory_flags);
}
static void switch_to_page_table(u8* page_table)
@ -220,7 +233,7 @@ void init_page_tables()
PageBumpAllocator allocator((u64*)page_tables_phys_start, (u64*)page_tables_phys_end);
auto root_table = allocator.take_page();
build_identity_map(allocator, root_table);
build_mappings(allocator, root_table);
setup_quickmap_page_table(allocator, root_table);
setup_kernel_page_directory(root_table);