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Kernel/aarch64: Set up quickmap infrastructure in initial page tables

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With this change the quickmap related functions in MemoryManager
actually work. :^)
This commit is contained in:
Timon Kruiper 2022-09-21 16:33:08 +02:00 committed by Andreas Kling
parent a62732ee2f
commit 96f73c9289
Notes: sideshowbarker 2024-07-17 06:30:06 +09:00 
Author: https://github.com/FireFox317
Commit: https://github.com/SerenityOS/serenity/commit/96f73c9289
Pull-request: https://github.com/SerenityOS/serenity/pull/15309
Reviewed-by: https://github.com/bgianfo
Reviewed-by: https://github.com/bugreport0
Reviewed-by: https://github.com/nico ✅
1 changed files with 52 additions and 32 deletions
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46
Kernel/Arch/aarch64/MMU.cpp
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@ -13,7 +13,9 @@
#include <Kernel/Arch/aarch64/RPi/MMIO.h> #include <Kernel/Arch/aarch64/RPi/MMIO.h>
#include <Kernel/Arch/aarch64/RPi/UART.h> #include <Kernel/Arch/aarch64/RPi/UART.h>
#include <Kernel/Arch/aarch64/Registers.h> #include <Kernel/Arch/aarch64/Registers.h>
#include <Kernel/BootInfo.h>
#include <Kernel/Panic.h> #include <Kernel/Panic.h>
#include <Kernel/Sections.h>
// Documentation here for Aarch64 Address Translations // Documentation here for Aarch64 Address Translations
// https://documentation-service.arm.com/static/5efa1d23dbdee951c1ccdec5?token= // https://documentation-service.arm.com/static/5efa1d23dbdee951c1ccdec5?token=
@ -79,15 +81,12 @@ private:
}; };
} }
static void insert_identity_entries_for_physical_memory_range(PageBumpAllocator& allocator, u64* page_table, FlatPtr start, FlatPtr end, u64 flags) static u64* insert_page_table(PageBumpAllocator& allocator, u64* page_table, VirtualAddress virtual_addr)
{ {
// Not very efficient, but simple and it works.
for (FlatPtr addr = start; addr < end; addr += GRANULE_SIZE) {
// Each level has 9 bits (512 entries) // Each level has 9 bits (512 entries)
u64 level0_idx = (addr >> 39) & 0x1FF; u64 level0_idx = (virtual_addr.get() >> 39) & 0x1FF;
u64 level1_idx = (addr >> 30) & 0x1FF; u64 level1_idx = (virtual_addr.get() >> 30) & 0x1FF;
u64 level2_idx = (addr >> 21) & 0x1FF; u64 level2_idx = (virtual_addr.get() >> 21) & 0x1FF;
u64 level3_idx = (addr >> 12) & 0x1FF;
u64* level1_table = page_table; u64* level1_table = page_table;
@ -110,17 +109,31 @@ static void insert_identity_entries_for_physical_memory_range(PageBumpAllocator&
level3_table[level2_idx] |= TABLE_DESCRIPTOR; level3_table[level2_idx] |= TABLE_DESCRIPTOR;
} }
u64* level4_table = descriptor_to_pointer(level3_table[level2_idx]); 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)
{
// 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 });
u64 level3_idx = (addr >> 12) & 0x1FF;
u64* l4_entry = &level4_table[level3_idx]; u64* l4_entry = &level4_table[level3_idx];
*l4_entry = addr; *l4_entry = addr;
*l4_entry |= flags; *l4_entry |= flags;
} }
} }
static void build_identity_map(PageBumpAllocator& allocator) static void setup_quickmap_page_table(PageBumpAllocator& allocator, u64* root_table)
{ {
u64* level1_table = allocator.take_page(); // FIXME: Rename boot_pd_kernel_pt1023 to quickmap_page_table
// FIXME: Rename KERNEL_PT1024_BASE to quickmap_page_table_address
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)
{
u64 normal_memory_flags = ACCESS_FLAG | PAGE_DESCRIPTOR | INNER_SHAREABLE | NORMAL_MEMORY; u64 normal_memory_flags = ACCESS_FLAG | PAGE_DESCRIPTOR | INNER_SHAREABLE | NORMAL_MEMORY;
u64 device_memory_flags = ACCESS_FLAG | PAGE_DESCRIPTOR | OUTER_SHAREABLE | DEVICE_MEMORY; u64 device_memory_flags = ACCESS_FLAG | PAGE_DESCRIPTOR | OUTER_SHAREABLE | DEVICE_MEMORY;
@ -128,8 +141,8 @@ static void build_identity_map(PageBumpAllocator& allocator)
FlatPtr start_of_range = ((FlatPtr)start_of_kernel_image & ~(FlatPtr)0x1fffff); FlatPtr start_of_range = ((FlatPtr)start_of_kernel_image & ~(FlatPtr)0x1fffff);
FlatPtr end_of_range = ((FlatPtr)end_of_kernel_image & ~(FlatPtr)0x1fffff) + 0x200000 - 1; FlatPtr end_of_range = ((FlatPtr)end_of_kernel_image & ~(FlatPtr)0x1fffff) + 0x200000 - 1;
insert_identity_entries_for_physical_memory_range(allocator, level1_table, start_of_range, end_of_range, normal_memory_flags); 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, level1_table, RPi::MMIO::the().peripheral_base_address(), RPi::MMIO::the().peripheral_end_address(), device_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);
} }
static void switch_to_page_table(u8* page_table) static void switch_to_page_table(u8* page_table)
@ -177,8 +190,15 @@ static void activate_mmu()
void init_page_tables() void init_page_tables()
{ {
// We currently identity map the physical memory, so the offset is 0.
physical_to_virtual_offset = 0;
kernel_mapping_base = 0;
PageBumpAllocator allocator((u64*)page_tables_phys_start, (u64*)page_tables_phys_end); PageBumpAllocator allocator((u64*)page_tables_phys_start, (u64*)page_tables_phys_end);
build_identity_map(allocator); auto root_table = allocator.take_page();
build_identity_map(allocator, root_table);
setup_quickmap_page_table(allocator, root_table);
switch_to_page_table(page_tables_phys_start); switch_to_page_table(page_tables_phys_start);
activate_mmu(); activate_mmu();
} }