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Revert "Kernel: Move Kernel mapping to 0xc0000000"

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This reverts commit bd33c66273.

This broke the network card drivers, since they depended on kmalloc
addresses being identity-mapped.
This commit is contained in:
Andreas Kling 2019-11-23 17:27:09 +01:00
parent f61ed8eab5
commit 9a157b5e81
13 changed files with 64 additions and 132 deletions
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50
Kernel/VM/MemoryManager.cpp
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@ -24,8 +24,7 @@ MemoryManager::MemoryManager(u32 physical_address_for_kernel_page_tables)
{
m_kernel_page_directory = PageDirectory::create_at_fixed_address(PhysicalAddress(physical_address_for_kernel_page_tables));
m_page_table_zero = (PageTableEntry*)(physical_address_for_kernel_page_tables + PAGE_SIZE);
m_page_table_768 = (PageTableEntry*)(physical_address_for_kernel_page_tables + PAGE_SIZE * 2);
m_page_table_769 = (PageTableEntry*)(physical_address_for_kernel_page_tables + PAGE_SIZE * 3);
m_page_table_one = (PageTableEntry*)(physical_address_for_kernel_page_tables + PAGE_SIZE * 2);
initialize_paging();
kprintf("MM initialized.\n");
@ -39,6 +38,7 @@ void MemoryManager::populate_page_directory(PageDirectory& page_directory)
{
page_directory.m_directory_page = allocate_supervisor_physical_page();
page_directory.entries()[0].copy_from({}, kernel_page_directory().entries()[0]);
page_directory.entries()[1].copy_from({}, kernel_page_directory().entries()[1]);
// Defer to the kernel page tables for 0xC0000000-0xFFFFFFFF
for (int i = 768; i < 1024; ++i)
page_directory.entries()[i].copy_from({}, kernel_page_directory().entries()[i]);
@ -47,6 +47,7 @@ void MemoryManager::populate_page_directory(PageDirectory& page_directory)
void MemoryManager::initialize_paging()
{
memset(m_page_table_zero, 0, PAGE_SIZE);
memset(m_page_table_one, 0, PAGE_SIZE);
#ifdef MM_DEBUG
dbgprintf("MM: Kernel page directory @ %p\n", kernel_page_directory().cr3());
@ -59,12 +60,16 @@ void MemoryManager::initialize_paging()
map_protected(VirtualAddress(0), PAGE_SIZE);
#ifdef MM_DEBUG
dbgprintf("MM: Identity map bottom 1MiB\n", kernel_virtual_base);
dbgprintf("MM: Identity map bottom 8MB\n");
#endif
create_identity_mapping(kernel_page_directory(), VirtualAddress(PAGE_SIZE), (1 * MB) - PAGE_SIZE);
// The bottom 8 MB (except for the null page) are identity mapped & supervisor only.
// Every process shares these mappings.
create_identity_mapping(kernel_page_directory(), VirtualAddress(PAGE_SIZE), (8 * MB) - PAGE_SIZE);
// FIXME: We should move everything kernel-related above the 0xc0000000 virtual mark.
// Basic physical memory map:
// 0 -> 1 MB Page table/directory / I/O memory region
// 0 -> 1 MB We're just leaving this alone for now.
// 1 -> 3 MB Kernel image.
// (last page before 2MB) Used by quickmap_page().
// 2 MB -> 4 MB kmalloc_eternal() space.
@ -73,10 +78,8 @@ void MemoryManager::initialize_paging()
// 8 MB -> MAX Userspace physical pages (available for allocation!)
// Basic virtual memory map:
// 0x00000000-0x00100000 Identity mapped for Kernel Physical pages handed out by allocate_supervisor_physical_page (for I/O, page tables etc).
// 0x00800000-0xbfffffff Userspace program virtual address space.
// 0xc0001000-0xc0800000 Kernel-only virtual address space. This area is mapped to the first 8 MB of physical memory and includes areas for kmalloc, etc.
// 0xc0800000-0xffffffff Kernel virtual address space for kernel Page Directory.
// 0 MB -> 8MB Identity mapped.
// 0xc0000000-0xffffffff Kernel-only virtual address space.
#ifdef MM_DEBUG
dbgprintf("MM: Quickmap will use %p\n", m_quickmap_addr.get());
@ -97,6 +100,10 @@ void MemoryManager::initialize_paging()
if (mmap->type != MULTIBOOT_MEMORY_AVAILABLE)
continue;
// FIXME: Maybe make use of stuff below the 1MB mark?
if (mmap->addr < (1 * MB))
continue;
if ((mmap->addr + mmap->len) > 0xffffffff)
continue;
@ -124,8 +131,9 @@ void MemoryManager::initialize_paging()
for (size_t page_base = mmap->addr; page_base < (mmap->addr + mmap->len); page_base += PAGE_SIZE) {
auto addr = PhysicalAddress(page_base);
// Anything below 1 * MB is a Kernel Physical region
if (page_base > PAGE_SIZE && page_base < 1 * MB) {
if (page_base < 7 * MB) {
// nothing
} else if (page_base >= 7 * MB && page_base < 8 * MB) {
if (region.is_null() || !region_is_super || region->upper().offset(PAGE_SIZE) != addr) {
m_super_physical_regions.append(PhysicalRegion::create(addr, addr));
region = m_super_physical_regions.last();
@ -133,7 +141,7 @@ void MemoryManager::initialize_paging()
} else {
region->expand(region->lower(), addr);
}
} else if (page_base > 8 * MB) {
} else {
if (region.is_null() || region_is_super || region->upper().offset(PAGE_SIZE) != addr) {
m_user_physical_regions.append(PhysicalRegion::create(addr, addr));
region = m_user_physical_regions.last();
@ -154,6 +162,7 @@ void MemoryManager::initialize_paging()
#ifdef MM_DEBUG
dbgprintf("MM: Installing page directory\n");
#endif
// Turn on CR4.PGE so the CPU will respect the G bit in page tables.
asm volatile(
"mov %cr4, %eax\n"
@ -166,6 +175,10 @@ void MemoryManager::initialize_paging()
"orl $0x80000001, %%eax\n"
"movl %%eax, %%cr0\n" ::
: "%eax", "memory");
#ifdef MM_DEBUG
dbgprintf("MM: Paging initialized.\n");
#endif
}
PageTableEntry& MemoryManager::ensure_pte(PageDirectory& page_directory, VirtualAddress vaddr)
@ -186,16 +199,9 @@ PageTableEntry& MemoryManager::ensure_pte(PageDirectory& page_directory, Virtual
pde.set_present(true);
pde.set_writable(true);
pde.set_global(true);
} else if (page_directory_index == 768) {
} else if (page_directory_index == 1) {
ASSERT(&page_directory == m_kernel_page_directory);
pde.set_page_table_base((u32)m_page_table_768);
pde.set_user_allowed(false);
pde.set_present(true);
pde.set_writable(true);
pde.set_global(true);
} else if (page_directory_index == 769) {
ASSERT(&page_directory == m_kernel_page_directory);
pde.set_page_table_base((u32)m_page_table_769);
pde.set_page_table_base((u32)m_page_table_one);
pde.set_user_allowed(false);
pde.set_present(true);
pde.set_writable(true);
@ -221,7 +227,7 @@ PageTableEntry& MemoryManager::ensure_pte(PageDirectory& page_directory, Virtual
page_directory.m_physical_pages.set(page_directory_index, move(page_table));
}
}
return pde.page_table_virtual_base()[page_table_index];
return pde.page_table_base()[page_table_index];
}
void MemoryManager::map_protected(VirtualAddress vaddr, size_t length)