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ladybird/Kernel/VM/MemoryManager.cpp
Andreas Kling 19398cd7d5 Kernel: Reorganize memory layout a bit 
Move the kernel image to the 1 MB physical mark. This prevents it from
colliding with stuff like the VGA memory. This was causing us to end
up with the BIOS screen contents sneaking into kernel memory sometimes.

This patch also bumps the kmalloc heap size from 1 MB to 3 MB. It's not
the perfect permanent solution (obviously) but it should get the OOM
monkey off our backs for a while.
2019-11-04 12:04:35 +01:00

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#include "CMOS.h"
#include "Process.h"
#include "StdLib.h"
#include <AK/Assertions.h>
#include <AK/kstdio.h>
#include <Kernel/Arch/i386/CPU.h>
#include <Kernel/FileSystem/Inode.h>
#include <Kernel/Multiboot.h>
#include <Kernel/VM/AnonymousVMObject.h>
#include <Kernel/VM/InodeVMObject.h>
#include <Kernel/VM/MemoryManager.h>
//#define MM_DEBUG
//#define PAGE_FAULT_DEBUG
static MemoryManager* s_the;
MemoryManager& MM
{
return *s_the;
}
MemoryManager::MemoryManager()
{
// FIXME: Hard-coding these is stupid. Find a better way.
m_kernel_page_directory = PageDirectory::create_at_fixed_address(PhysicalAddress(0x4000));
m_page_table_zero = (PageTableEntry*)0x6000;
m_page_table_one = (PageTableEntry*)0x7000;
initialize_paging();
kprintf("MM initialized.\n");
}
MemoryManager::~MemoryManager()
{
}
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]);
}
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());
#endif
#ifdef MM_DEBUG
dbgprintf("MM: Protect against null dereferences\n");
#endif
// Make null dereferences crash.
map_protected(VirtualAddress(0), PAGE_SIZE);
#ifdef MM_DEBUG
dbgprintf("MM: Identity map bottom 8MB\n");
#endif
// 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 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.
// 4 MB -> 7 MB kmalloc() space.
// 7 MB -> 8 MB Supervisor physical pages (available for allocation!)
// 8 MB -> MAX Userspace physical pages (available for allocation!)
// Basic virtual memory map:
// 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());
#endif
m_quickmap_addr = VirtualAddress((2 * MB) - PAGE_SIZE);
RefPtr<PhysicalRegion> region;
bool region_is_super = false;
for (auto* mmap = (multiboot_memory_map_t*)multiboot_info_ptr->mmap_addr; (unsigned long)mmap < multiboot_info_ptr->mmap_addr + multiboot_info_ptr->mmap_length; mmap = (multiboot_memory_map_t*)((unsigned long)mmap + mmap->size + sizeof(mmap->size))) {
kprintf("MM: Multiboot mmap: base_addr = 0x%x%08x, length = 0x%x%08x, type = 0x%x\n",
(u32)(mmap->addr >> 32),
(u32)(mmap->addr & 0xffffffff),
(u32)(mmap->len >> 32),
(u32)(mmap->len & 0xffffffff),
(u32)mmap->type);
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;
auto diff = (u32)mmap->addr % PAGE_SIZE;
if (diff != 0) {
kprintf("MM: got an unaligned region base from the bootloader; correcting %p by %d bytes\n", mmap->addr, diff);
diff = PAGE_SIZE - diff;
mmap->addr += diff;
mmap->len -= diff;
}
if ((mmap->len % PAGE_SIZE) != 0) {
kprintf("MM: got an unaligned region length from the bootloader; correcting %d by %d bytes\n", mmap->len, mmap->len % PAGE_SIZE);
mmap->len -= mmap->len % PAGE_SIZE;
}
if (mmap->len < PAGE_SIZE) {
kprintf("MM: memory region from bootloader is too small; we want >= %d bytes, but got %d bytes\n", PAGE_SIZE, mmap->len);
continue;
}
#ifdef MM_DEBUG
kprintf("MM: considering memory at %p - %p\n",
(u32)mmap->addr, (u32)(mmap->addr + mmap->len));
#endif
for (size_t page_base = mmap->addr; page_base < (mmap->addr + mmap->len); page_base += PAGE_SIZE) {
auto addr = PhysicalAddress(page_base);
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();
region_is_super = true;
} else {
region->expand(region->lower(), addr);
}
} 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();
region_is_super = false;
} else {
region->expand(region->lower(), addr);
}
}
}
}
for (auto& region : m_super_physical_regions)
m_super_physical_pages += region.finalize_capacity();
for (auto& region : m_user_physical_regions)
m_user_physical_pages += region.finalize_capacity();
#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"
"orl $0x10, %eax\n"
"mov %eax, %cr4\n");
asm volatile("movl %%eax, %%cr3" ::"a"(kernel_page_directory().cr3()));
asm volatile(
"movl %%cr0, %%eax\n"
"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)
{
ASSERT_INTERRUPTS_DISABLED();
u32 page_directory_index = (vaddr.get() >> 22) & 0x3ff;
u32 page_table_index = (vaddr.get() >> 12) & 0x3ff;
PageDirectoryEntry& pde = page_directory.entries()[page_directory_index];
if (!pde.is_present()) {
#ifdef MM_DEBUG
dbgprintf("MM: PDE %u not present (requested for V%p), allocating\n", page_directory_index, vaddr.get());
#endif
if (page_directory_index == 0) {
ASSERT(&page_directory == m_kernel_page_directory);
pde.set_page_table_base((u32)m_page_table_zero);
pde.set_user_allowed(false);
pde.set_present(true);
pde.set_writable(true);
pde.set_global(true);
} else if (page_directory_index == 1) {
ASSERT(&page_directory == m_kernel_page_directory);
pde.set_page_table_base((u32)m_page_table_one);
pde.set_user_allowed(false);
pde.set_present(true);
pde.set_writable(true);
pde.set_global(true);
} else {
//ASSERT(&page_directory != m_kernel_page_directory.ptr());
auto page_table = allocate_supervisor_physical_page();
#ifdef MM_DEBUG
dbgprintf("MM: PD K%p (%s) at P%p allocated page table #%u (for V%p) at P%p\n",
&page_directory,
&page_directory == m_kernel_page_directory ? "Kernel" : "User",
page_directory.cr3(),
page_directory_index,
vaddr.get(),
page_table->paddr().get());
#endif
pde.set_page_table_base(page_table->paddr().get());
pde.set_user_allowed(true);
pde.set_present(true);
pde.set_writable(true);
pde.set_global(&page_directory == m_kernel_page_directory.ptr());
page_directory.m_physical_pages.set(page_directory_index, move(page_table));
}
}
return pde.page_table_base()[page_table_index];
}
void MemoryManager::map_protected(VirtualAddress vaddr, size_t length)
{
InterruptDisabler disabler;
ASSERT(vaddr.is_page_aligned());
for (u32 offset = 0; offset < length; offset += PAGE_SIZE) {
auto pte_address = vaddr.offset(offset);
auto& pte = ensure_pte(kernel_page_directory(), pte_address);
pte.set_physical_page_base(pte_address.get());
pte.set_user_allowed(false);
pte.set_present(false);
pte.set_writable(false);
flush_tlb(pte_address);
}
}
void MemoryManager::create_identity_mapping(PageDirectory& page_directory, VirtualAddress vaddr, size_t size)
{
InterruptDisabler disabler;
ASSERT((vaddr.get() & ~PAGE_MASK) == 0);
for (u32 offset = 0; offset < size; offset += PAGE_SIZE) {
auto pte_address = vaddr.offset(offset);
auto& pte = ensure_pte(page_directory, pte_address);
pte.set_physical_page_base(pte_address.get());
pte.set_user_allowed(false);
pte.set_present(true);
pte.set_writable(true);
page_directory.flush(pte_address);
}
}
void MemoryManager::initialize()
{
s_the = new MemoryManager;
}
Region* MemoryManager::kernel_region_from_vaddr(VirtualAddress vaddr)
{
if (vaddr.get() < 0xc0000000)
return nullptr;
for (auto& region : MM.m_kernel_regions) {
if (region.contains(vaddr))
return &region;
}
return nullptr;
}
Region* MemoryManager::user_region_from_vaddr(Process& process, VirtualAddress vaddr)
{
// FIXME: Use a binary search tree (maybe red/black?) or some other more appropriate data structure!
for (auto& region : process.m_regions) {
if (region.contains(vaddr))
return &region;
}
dbg() << process << " Couldn't find user region for " << vaddr;
return nullptr;
}
Region* MemoryManager::region_from_vaddr(Process& process, VirtualAddress vaddr)
{
ASSERT_INTERRUPTS_DISABLED();
if (auto* region = kernel_region_from_vaddr(vaddr))
return region;
return user_region_from_vaddr(process, vaddr);
}
const Region* MemoryManager::region_from_vaddr(const Process& process, VirtualAddress vaddr)
{
if (auto* region = kernel_region_from_vaddr(vaddr))
return region;
return user_region_from_vaddr(const_cast<Process&>(process), vaddr);
}
Region* MemoryManager::region_from_vaddr(VirtualAddress vaddr)
{
if (auto* region = kernel_region_from_vaddr(vaddr))
return region;
auto page_directory = PageDirectory::find_by_pdb(cpu_cr3());
if (!page_directory)
return nullptr;
ASSERT(page_directory->process());
return user_region_from_vaddr(*page_directory->process(), vaddr);
}
PageFaultResponse MemoryManager::handle_page_fault(const PageFault& fault)
{
ASSERT_INTERRUPTS_DISABLED();
ASSERT(current);
#ifdef PAGE_FAULT_DEBUG
dbgprintf("MM: handle_page_fault(%w) at V%p\n", fault.code(), fault.vaddr().get());
#endif
ASSERT(fault.vaddr() != m_quickmap_addr);
if (fault.type() == PageFault::Type::PageNotPresent && fault.vaddr().get() >= 0xc0000000) {
auto* current_page_directory = reinterpret_cast<PageDirectoryEntry*>(cpu_cr3());
u32 page_directory_index = (fault.vaddr().get() >> 22) & 0x3ff;
auto& kernel_pde = kernel_page_directory().entries()[page_directory_index];
auto& current_pde = current_page_directory[page_directory_index];
if (kernel_pde.is_present() && !current_pde.is_present()) {
dbg() << "NP(kernel): Copying new kernel mapping for " << fault.vaddr() << " into current page directory";
current_pde.copy_from({}, kernel_pde);
flush_tlb(fault.vaddr().page_base());
return PageFaultResponse::Continue;
}
}
auto* region = region_from_vaddr(fault.vaddr());
if (!region) {
kprintf("NP(error) fault at invalid address V%p\n", fault.vaddr().get());
return PageFaultResponse::ShouldCrash;
}
return region->handle_fault(fault);
}
OwnPtr<Region> MemoryManager::allocate_kernel_region(size_t size, const StringView& name, bool user_accessible, bool should_commit)
{
InterruptDisabler disabler;
ASSERT(!(size % PAGE_SIZE));
auto range = kernel_page_directory().range_allocator().allocate_anywhere(size);
ASSERT(range.is_valid());
OwnPtr<Region> region;
if (user_accessible)
region = Region::create_user_accessible(range, name, PROT_READ | PROT_WRITE | PROT_EXEC);
else
region = Region::create_kernel_only(range, name, PROT_READ | PROT_WRITE | PROT_EXEC);
region->map(kernel_page_directory());
// FIXME: It would be cool if these could zero-fill on demand instead.
if (should_commit)
region->commit();
return region;
}
OwnPtr<Region> MemoryManager::allocate_user_accessible_kernel_region(size_t size, const StringView& name)
{
return allocate_kernel_region(size, name, true);
}
void MemoryManager::deallocate_user_physical_page(PhysicalPage&& page)
{
for (auto& region : m_user_physical_regions) {
if (!region.contains(page)) {
kprintf(
"MM: deallocate_user_physical_page: %p not in %p -> %p\n",
page.paddr(), region.lower().get(), region.upper().get());
continue;
}
region.return_page(move(page));
--m_user_physical_pages_used;
return;
}
kprintf("MM: deallocate_user_physical_page couldn't figure out region for user page @ %p\n", page.paddr());
ASSERT_NOT_REACHED();
}
RefPtr<PhysicalPage> MemoryManager::allocate_user_physical_page(ShouldZeroFill should_zero_fill)
{
InterruptDisabler disabler;
RefPtr<PhysicalPage> page;
for (auto& region : m_user_physical_regions) {
page = region.take_free_page(false);
if (page.is_null())
continue;
}
if (!page) {
if (m_user_physical_regions.is_empty()) {
kprintf("MM: no user physical regions available (?)\n");
}
kprintf("MM: no user physical pages available\n");
ASSERT_NOT_REACHED();
return {};
}
#ifdef MM_DEBUG
dbgprintf("MM: allocate_user_physical_page vending P%p\n", page->paddr().get());
#endif
if (should_zero_fill == ShouldZeroFill::Yes) {
auto* ptr = (u32*)quickmap_page(*page);
fast_u32_fill(ptr, 0, PAGE_SIZE / sizeof(u32));
unquickmap_page();
}
++m_user_physical_pages_used;
return page;
}
void MemoryManager::deallocate_supervisor_physical_page(PhysicalPage&& page)
{
for (auto& region : m_super_physical_regions) {
if (!region.contains(page)) {
kprintf(
"MM: deallocate_supervisor_physical_page: %p not in %p -> %p\n",
page.paddr(), region.lower().get(), region.upper().get());
continue;
}
region.return_page(move(page));
--m_super_physical_pages_used;
return;
}
kprintf("MM: deallocate_supervisor_physical_page couldn't figure out region for super page @ %p\n", page.paddr());
ASSERT_NOT_REACHED();
}
RefPtr<PhysicalPage> MemoryManager::allocate_supervisor_physical_page()
{
InterruptDisabler disabler;
RefPtr<PhysicalPage> page;
for (auto& region : m_super_physical_regions) {
page = region.take_free_page(true);
if (page.is_null())
continue;
}
if (!page) {
if (m_super_physical_regions.is_empty()) {
kprintf("MM: no super physical regions available (?)\n");
}
kprintf("MM: no super physical pages available\n");
ASSERT_NOT_REACHED();
return {};
}
#ifdef MM_DEBUG
dbgprintf("MM: allocate_supervisor_physical_page vending P%p\n", page->paddr().get());
#endif
fast_u32_fill((u32*)page->paddr().as_ptr(), 0, PAGE_SIZE / sizeof(u32));
++m_super_physical_pages_used;
return page;
}
void MemoryManager::enter_process_paging_scope(Process& process)
{
ASSERT(current);
InterruptDisabler disabler;
current->tss().cr3 = process.page_directory().cr3();
asm volatile("movl %%eax, %%cr3" ::"a"(process.page_directory().cr3())
: "memory");
}
void MemoryManager::flush_entire_tlb()
{
asm volatile(
"mov %%cr3, %%eax\n"
"mov %%eax, %%cr3\n" ::
: "%eax", "memory");
}
void MemoryManager::flush_tlb(VirtualAddress vaddr)
{
asm volatile("invlpg %0"
:
: "m"(*(char*)vaddr.get())
: "memory");
}
void MemoryManager::map_for_kernel(VirtualAddress vaddr, PhysicalAddress paddr, bool cache_disabled)
{
auto& pte = ensure_pte(kernel_page_directory(), vaddr);
pte.set_physical_page_base(paddr.get());
pte.set_present(true);
pte.set_writable(true);
pte.set_user_allowed(false);
pte.set_cache_disabled(cache_disabled);
flush_tlb(vaddr);
}
u8* MemoryManager::quickmap_page(PhysicalPage& physical_page)
{
ASSERT_INTERRUPTS_DISABLED();
ASSERT(!m_quickmap_in_use);
m_quickmap_in_use = true;
auto page_vaddr = m_quickmap_addr;
auto& pte = ensure_pte(kernel_page_directory(), page_vaddr);
pte.set_physical_page_base(physical_page.paddr().get());
pte.set_present(true);
pte.set_writable(true);
pte.set_user_allowed(false);
flush_tlb(page_vaddr);
ASSERT((u32)pte.physical_page_base() == physical_page.paddr().get());
#ifdef MM_DEBUG
dbg() << "MM: >> quickmap_page " << page_vaddr << " => " << physical_page.paddr() << " @ PTE=" << (void*)pte.raw() << " {" << &pte << "}";
#endif
return page_vaddr.as_ptr();
}
void MemoryManager::unquickmap_page()
{
ASSERT_INTERRUPTS_DISABLED();
ASSERT(m_quickmap_in_use);
auto page_vaddr = m_quickmap_addr;
auto& pte = ensure_pte(kernel_page_directory(), page_vaddr);
#ifdef MM_DEBUG
auto old_physical_address = pte.physical_page_base();
#endif
pte.set_physical_page_base(0);
pte.set_present(false);
pte.set_writable(false);
flush_tlb(page_vaddr);
#ifdef MM_DEBUG
dbg() << "MM: >> unquickmap_page " << page_vaddr << " =/> " << old_physical_address;
#endif
m_quickmap_in_use = false;
}
bool MemoryManager::validate_user_read(const Process& process, VirtualAddress vaddr) const
{
auto* region = region_from_vaddr(process, vaddr);
return region && region->is_readable();
}
bool MemoryManager::validate_user_write(const Process& process, VirtualAddress vaddr) const
{
auto* region = region_from_vaddr(process, vaddr);
return region && region->is_writable();
}
void MemoryManager::register_vmo(VMObject& vmo)
{
InterruptDisabler disabler;
m_vmobjects.append(&vmo);
}
void MemoryManager::unregister_vmo(VMObject& vmo)
{
InterruptDisabler disabler;
m_vmobjects.remove(&vmo);
}
void MemoryManager::register_region(Region& region)
{
InterruptDisabler disabler;
if (region.vaddr().get() >= 0xc0000000)
m_kernel_regions.append(&region);
else
m_user_regions.append(&region);
}
void MemoryManager::unregister_region(Region& region)
{
InterruptDisabler disabler;
if (region.vaddr().get() >= 0xc0000000)
m_kernel_regions.remove(&region);
else
m_user_regions.remove(&region);
}
ProcessPagingScope::ProcessPagingScope(Process& process)
{
ASSERT(current);
MM.enter_process_paging_scope(process);
}
ProcessPagingScope::~ProcessPagingScope()
{
MM.enter_process_paging_scope(current->process());
}
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