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Kernel: Move VM-related files into Kernel/VM/.

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Also break MemoryManager.{cpp,h} into one file per class.
This commit is contained in:
Andreas Kling 2019-04-03 15:13:07 +02:00
parent 39fd81174e
commit b9738fa8ac
21 changed files with 630 additions and 575 deletions
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2
Kernel/VM/.gitignore vendored Normal file
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*.o
*.d

642
Kernel/VM/MemoryManager.cpp Normal file
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#include <Kernel/VM/MemoryManager.h>
#include <AK/Assertions.h>
#include <AK/kstdio.h>
#include "i386.h"
#include "StdLib.h"
#include "Process.h"
#include "CMOS.h"
//#define MM_DEBUG
//#define PAGE_FAULT_DEBUG
static MemoryManager* s_the;
unsigned MemoryManager::s_user_physical_pages_in_existence;
unsigned MemoryManager::s_super_physical_pages_in_existence;
MemoryManager& MM
{
return *s_the;
}
MemoryManager::MemoryManager()
{
// FIXME: This is not the best way to do memory map detection.
// Rewrite to use BIOS int 15,e820 once we have VM86 support.
word base_memory = (CMOS::read(0x16) << 8) | CMOS::read(0x15);
word ext_memory = (CMOS::read(0x18) << 8) | CMOS::read(0x17);
kprintf("%u kB base memory\n", base_memory);
kprintf("%u kB extended memory\n", ext_memory);
m_ram_size = ext_memory * 1024;
m_kernel_page_directory = PageDirectory::create_at_fixed_address(PhysicalAddress(0x4000));
m_page_table_zero = (dword*)0x6000;
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] = kernel_page_directory().entries()[0];
// Defer to the kernel page tables for 0xC0000000-0xFFFFFFFF
for (int i = 768; i < 1024; ++i)
page_directory.entries()[i] = kernel_page_directory().entries()[i];
}
void MemoryManager::initialize_paging()
{
static_assert(sizeof(MemoryManager::PageDirectoryEntry) == 4);
static_assert(sizeof(MemoryManager::PageTableEntry) == 4);
memset(m_page_table_zero, 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(LinearAddress(0), PAGE_SIZE);
#ifdef MM_DEBUG
dbgprintf("MM: Identity map bottom 4MB\n");
#endif
// The bottom 4 MB (except for the null page) are identity mapped & supervisor only.
// Every process shares these mappings.
create_identity_mapping(kernel_page_directory(), LinearAddress(PAGE_SIZE), (4 * MB) - PAGE_SIZE);
// Basic memory map:
// 0 -> 512 kB Kernel code. Root page directory & PDE 0.
// (last page before 1MB) Used by quickmap_page().
// 1 MB -> 2 MB kmalloc_eternal() space.
// 2 MB -> 3 MB kmalloc() space.
// 3 MB -> 4 MB Supervisor physical pages (available for allocation!)
// 4 MB -> (max) MB Userspace physical pages (available for allocation!)
for (size_t i = (2 * MB); i < (4 * MB); i += PAGE_SIZE)
m_free_supervisor_physical_pages.append(PhysicalPage::create_eternal(PhysicalAddress(i), true));
dbgprintf("MM: 4MB-%uMB available for allocation\n", m_ram_size / 1048576);
for (size_t i = (4 * MB); i < m_ram_size; i += PAGE_SIZE)
m_free_physical_pages.append(PhysicalPage::create_eternal(PhysicalAddress(i), false));
m_quickmap_addr = LinearAddress((1 * MB) - PAGE_SIZE);
#ifdef MM_DEBUG
dbgprintf("MM: Quickmap will use P%x\n", m_quickmap_addr.get());
dbgprintf("MM: Installing page directory\n");
#endif
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
}
RetainPtr<PhysicalPage> MemoryManager::allocate_page_table(PageDirectory& page_directory, unsigned index)
{
ASSERT(!page_directory.m_physical_pages.contains(index));
auto physical_page = allocate_supervisor_physical_page();
if (!physical_page)
return nullptr;
page_directory.m_physical_pages.set(index, physical_page.copy_ref());
return physical_page;
}
void MemoryManager::remove_identity_mapping(PageDirectory& page_directory, LinearAddress laddr, size_t size)
{
InterruptDisabler disabler;
// FIXME: ASSERT(laddr is 4KB aligned);
for (dword offset = 0; offset < size; offset += PAGE_SIZE) {
auto pte_address = laddr.offset(offset);
auto pte = ensure_pte(page_directory, pte_address);
pte.set_physical_page_base(0);
pte.set_user_allowed(false);
pte.set_present(true);
pte.set_writable(true);
flush_tlb(pte_address);
}
}
auto MemoryManager::ensure_pte(PageDirectory& page_directory, LinearAddress laddr) -> PageTableEntry
{
ASSERT_INTERRUPTS_DISABLED();
dword page_directory_index = (laddr.get() >> 22) & 0x3ff;
dword page_table_index = (laddr.get() >> 12) & 0x3ff;
PageDirectoryEntry pde = PageDirectoryEntry(&page_directory.entries()[page_directory_index]);
if (!pde.is_present()) {
#ifdef MM_DEBUG
dbgprintf("MM: PDE %u not present (requested for L%x), allocating\n", page_directory_index, laddr.get());
#endif
if (page_directory_index == 0) {
ASSERT(&page_directory == m_kernel_page_directory.ptr());
pde.set_page_table_base((dword)m_page_table_zero);
pde.set_user_allowed(false);
pde.set_present(true);
pde.set_writable(true);
} else {
//ASSERT(&page_directory != m_kernel_page_directory.ptr());
auto page_table = allocate_page_table(page_directory, page_directory_index);
#ifdef MM_DEBUG
dbgprintf("MM: PD K%x (%s) at P%x allocated page table #%u (for L%x) at P%x\n",
&page_directory,
&page_directory == m_kernel_page_directory.ptr() ? "Kernel" : "User",
page_directory.cr3(),
page_directory_index,
laddr.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);
page_directory.m_physical_pages.set(page_directory_index, move(page_table));
}
}
return PageTableEntry(&pde.page_table_base()[page_table_index]);
}
void MemoryManager::map_protected(LinearAddress laddr, size_t length)
{
InterruptDisabler disabler;
// FIXME: ASSERT(linearAddress is 4KB aligned);
for (dword offset = 0; offset < length; offset += PAGE_SIZE) {
auto pte_address = laddr.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, LinearAddress laddr, size_t size)
{
InterruptDisabler disabler;
ASSERT((laddr.get() & ~PAGE_MASK) == 0);
for (dword offset = 0; offset < size; offset += PAGE_SIZE) {
auto pte_address = laddr.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::region_from_laddr(Process& process, LinearAddress laddr)
{
ASSERT_INTERRUPTS_DISABLED();
// 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(laddr))
return region.ptr();
}
dbgprintf("%s(%u) Couldn't find region for L%x (CR3=%x)\n", process.name().characters(), process.pid(), laddr.get(), process.page_directory().cr3());
return nullptr;
}
const Region* MemoryManager::region_from_laddr(const Process& process, LinearAddress laddr)
{
// 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(laddr))
return region.ptr();
}
dbgprintf("%s(%u) Couldn't find region for L%x (CR3=%x)\n", process.name().characters(), process.pid(), laddr.get(), process.page_directory().cr3());
return nullptr;
}
bool MemoryManager::zero_page(Region& region, unsigned page_index_in_region)
{
ASSERT_INTERRUPTS_DISABLED();
auto& vmo = region.vmo();
auto& vmo_page = vmo.physical_pages()[region.first_page_index() + page_index_in_region];
sti();
LOCKER(vmo.m_paging_lock);
cli();
if (!vmo_page.is_null()) {
#ifdef PAGE_FAULT_DEBUG
dbgprintf("MM: zero_page() but page already present. Fine with me!\n");
#endif
remap_region_page(region, page_index_in_region, true);
return true;
}
auto physical_page = allocate_physical_page(ShouldZeroFill::Yes);
#ifdef PAGE_FAULT_DEBUG
dbgprintf(" >> ZERO P%x\n", physical_page->paddr().get());
#endif
region.m_cow_map.set(page_index_in_region, false);
vmo.physical_pages()[page_index_in_region] = move(physical_page);
remap_region_page(region, page_index_in_region, true);
return true;
}
bool MemoryManager::copy_on_write(Region& region, unsigned page_index_in_region)
{
ASSERT_INTERRUPTS_DISABLED();
auto& vmo = region.vmo();
if (vmo.physical_pages()[page_index_in_region]->retain_count() == 1) {
#ifdef PAGE_FAULT_DEBUG
dbgprintf(" >> It's a COW page but nobody is sharing it anymore. Remap r/w\n");
#endif
region.m_cow_map.set(page_index_in_region, false);
remap_region_page(region, page_index_in_region, true);
return true;
}
#ifdef PAGE_FAULT_DEBUG
dbgprintf(" >> It's a COW page and it's time to COW!\n");
#endif
auto physical_page_to_copy = move(vmo.physical_pages()[page_index_in_region]);
auto physical_page = allocate_physical_page(ShouldZeroFill::No);
byte* dest_ptr = quickmap_page(*physical_page);
const byte* src_ptr = region.laddr().offset(page_index_in_region * PAGE_SIZE).as_ptr();
#ifdef PAGE_FAULT_DEBUG
dbgprintf(" >> COW P%x <- P%x\n", physical_page->paddr().get(), physical_page_to_copy->paddr().get());
#endif
memcpy(dest_ptr, src_ptr, PAGE_SIZE);
vmo.physical_pages()[page_index_in_region] = move(physical_page);
unquickmap_page();
region.m_cow_map.set(page_index_in_region, false);
remap_region_page(region, page_index_in_region, true);
return true;
}
bool MemoryManager::page_in_from_inode(Region& region, unsigned page_index_in_region)
{
ASSERT(region.page_directory());
auto& vmo = region.vmo();
ASSERT(!vmo.is_anonymous());
ASSERT(vmo.inode());
auto& vmo_page = vmo.physical_pages()[region.first_page_index() + page_index_in_region];
InterruptFlagSaver saver;
sti();
LOCKER(vmo.m_paging_lock);
cli();
if (!vmo_page.is_null()) {
dbgprintf("MM: page_in_from_inode() but page already present. Fine with me!\n");
remap_region_page(region, page_index_in_region, true);
return true;
}
#ifdef MM_DEBUG
dbgprintf("MM: page_in_from_inode ready to read from inode\n");
#endif
sti();
byte page_buffer[PAGE_SIZE];
auto& inode = *vmo.inode();
auto nread = inode.read_bytes(vmo.inode_offset() + ((region.first_page_index() + page_index_in_region) * PAGE_SIZE), PAGE_SIZE, page_buffer, nullptr);
if (nread < 0) {
kprintf("MM: page_in_from_inode had error (%d) while reading!\n", nread);
return false;
}
if (nread < PAGE_SIZE) {
// If we read less than a page, zero out the rest to avoid leaking uninitialized data.
memset(page_buffer + nread, 0, PAGE_SIZE - nread);
}
cli();
vmo_page = allocate_physical_page(ShouldZeroFill::No);
if (vmo_page.is_null()) {
kprintf("MM: page_in_from_inode was unable to allocate a physical page\n");
return false;
}
remap_region_page(region, page_index_in_region, true);
byte* dest_ptr = region.laddr().offset(page_index_in_region * PAGE_SIZE).as_ptr();
memcpy(dest_ptr, page_buffer, PAGE_SIZE);
return true;
}
PageFaultResponse MemoryManager::handle_page_fault(const PageFault& fault)
{
ASSERT_INTERRUPTS_DISABLED();
ASSERT(current);
#ifdef PAGE_FAULT_DEBUG
dbgprintf("MM: handle_page_fault(%w) at L%x\n", fault.code(), fault.laddr().get());
#endif
ASSERT(fault.laddr() != m_quickmap_addr);
auto* region = region_from_laddr(current->process(), fault.laddr());
if (!region) {
kprintf("NP(error) fault at invalid address L%x\n", fault.laddr().get());
return PageFaultResponse::ShouldCrash;
}
auto page_index_in_region = region->page_index_from_address(fault.laddr());
if (fault.is_not_present()) {
if (region->vmo().inode()) {
#ifdef PAGE_FAULT_DEBUG
dbgprintf("NP(inode) fault in Region{%p}[%u]\n", region, page_index_in_region);
#endif
page_in_from_inode(*region, page_index_in_region);
return PageFaultResponse::Continue;
} else {
#ifdef PAGE_FAULT_DEBUG
dbgprintf("NP(zero) fault in Region{%p}[%u]\n", region, page_index_in_region);
#endif
zero_page(*region, page_index_in_region);
return PageFaultResponse::Continue;
}
} else if (fault.is_protection_violation()) {
if (region->m_cow_map.get(page_index_in_region)) {
#ifdef PAGE_FAULT_DEBUG
dbgprintf("PV(cow) fault in Region{%p}[%u]\n", region, page_index_in_region);
#endif
bool success = copy_on_write(*region, page_index_in_region);
ASSERT(success);
return PageFaultResponse::Continue;
}
kprintf("PV(error) fault in Region{%p}[%u] at L%x\n", region, page_index_in_region, fault.laddr().get());
} else {
ASSERT_NOT_REACHED();
}
return PageFaultResponse::ShouldCrash;
}
RetainPtr<PhysicalPage> MemoryManager::allocate_physical_page(ShouldZeroFill should_zero_fill)
{
InterruptDisabler disabler;
if (1 > m_free_physical_pages.size()) {
kprintf("FUCK! No physical pages available.\n");
ASSERT_NOT_REACHED();
return { };
}
#ifdef MM_DEBUG
dbgprintf("MM: allocate_physical_page vending P%x (%u remaining)\n", m_free_physical_pages.last()->paddr().get(), m_free_physical_pages.size());
#endif
auto physical_page = m_free_physical_pages.take_last();
if (should_zero_fill == ShouldZeroFill::Yes) {
auto* ptr = (dword*)quickmap_page(*physical_page);
fast_dword_fill(ptr, 0, PAGE_SIZE / sizeof(dword));
unquickmap_page();
}
return physical_page;
}
RetainPtr<PhysicalPage> MemoryManager::allocate_supervisor_physical_page()
{
InterruptDisabler disabler;
if (1 > m_free_supervisor_physical_pages.size()) {
kprintf("FUCK! No physical pages available.\n");
ASSERT_NOT_REACHED();
return { };
}
#ifdef MM_DEBUG
dbgprintf("MM: allocate_supervisor_physical_page vending P%x (%u remaining)\n", m_free_supervisor_physical_pages.last()->paddr().get(), m_free_supervisor_physical_pages.size());
#endif
auto physical_page = m_free_supervisor_physical_pages.take_last();
fast_dword_fill((dword*)physical_page->paddr().as_ptr(), 0, PAGE_SIZE / sizeof(dword));
return physical_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::enter_kernel_paging_scope()
{
InterruptDisabler disabler;
asm volatile("movl %%eax, %%cr3"::"a"(kernel_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(LinearAddress laddr)
{
asm volatile("invlpg %0": :"m" (*(char*)laddr.get()) : "memory");
}
void MemoryManager::map_for_kernel(LinearAddress laddr, PhysicalAddress paddr)
{
auto pte = ensure_pte(kernel_page_directory(), laddr);
pte.set_physical_page_base(paddr.get());
pte.set_present(true);
pte.set_writable(true);
pte.set_user_allowed(false);
flush_tlb(laddr);
}
byte* MemoryManager::quickmap_page(PhysicalPage& physical_page)
{
ASSERT_INTERRUPTS_DISABLED();
ASSERT(!m_quickmap_in_use);
m_quickmap_in_use = true;
auto page_laddr = m_quickmap_addr;
auto pte = ensure_pte(kernel_page_directory(), page_laddr);
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_laddr);
ASSERT((dword)pte.physical_page_base() == physical_page.paddr().get());
#ifdef MM_DEBUG
dbgprintf("MM: >> quickmap_page L%x => P%x @ PTE=%p\n", page_laddr, physical_page.paddr().get(), pte.ptr());
#endif
return page_laddr.as_ptr();
}
void MemoryManager::unquickmap_page()
{
ASSERT_INTERRUPTS_DISABLED();
ASSERT(m_quickmap_in_use);
auto page_laddr = m_quickmap_addr;
auto pte = ensure_pte(kernel_page_directory(), page_laddr);
#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_laddr);
#ifdef MM_DEBUG
dbgprintf("MM: >> unquickmap_page L%x =/> P%x\n", page_laddr, old_physical_address);
#endif
m_quickmap_in_use = false;
}
void MemoryManager::remap_region_page(Region& region, unsigned page_index_in_region, bool user_allowed)
{
ASSERT(region.page_directory());
InterruptDisabler disabler;
auto page_laddr = region.laddr().offset(page_index_in_region * PAGE_SIZE);
auto pte = ensure_pte(*region.page_directory(), page_laddr);
auto& physical_page = region.vmo().physical_pages()[page_index_in_region];
ASSERT(physical_page);
pte.set_physical_page_base(physical_page->paddr().get());
pte.set_present(true); // FIXME: Maybe we should use the is_readable flag here?
if (region.m_cow_map.get(page_index_in_region))
pte.set_writable(false);
else
pte.set_writable(region.is_writable());
pte.set_cache_disabled(!region.vmo().m_allow_cpu_caching);
pte.set_write_through(!region.vmo().m_allow_cpu_caching);
pte.set_user_allowed(user_allowed);
region.page_directory()->flush(page_laddr);
#ifdef MM_DEBUG
dbgprintf("MM: >> remap_region_page (PD=%x, PTE=P%x) '%s' L%x => P%x (@%p)\n", region.page_directory()->cr3(), pte.ptr(), region.name().characters(), page_laddr.get(), physical_page->paddr().get(), physical_page.ptr());
#endif
}
void MemoryManager::remap_region(PageDirectory& page_directory, Region& region)
{
InterruptDisabler disabler;
ASSERT(region.page_directory() == &page_directory);
map_region_at_address(page_directory, region, region.laddr(), true);
}
void MemoryManager::map_region_at_address(PageDirectory& page_directory, Region& region, LinearAddress laddr, bool user_allowed)
{
InterruptDisabler disabler;
region.set_page_directory(page_directory);
auto& vmo = region.vmo();
#ifdef MM_DEBUG
dbgprintf("MM: map_region_at_address will map VMO pages %u - %u (VMO page count: %u)\n", region.first_page_index(), region.last_page_index(), vmo.page_count());
#endif
for (size_t i = 0; i < region.page_count(); ++i) {
auto page_laddr = laddr.offset(i * PAGE_SIZE);
auto pte = ensure_pte(page_directory, page_laddr);
auto& physical_page = vmo.physical_pages()[region.first_page_index() + i];
if (physical_page) {
pte.set_physical_page_base(physical_page->paddr().get());
pte.set_present(true); // FIXME: Maybe we should use the is_readable flag here?
// FIXME: It seems wrong that the *region* cow map is essentially using *VMO* relative indices.
if (region.m_cow_map.get(region.first_page_index() + i))
pte.set_writable(false);
else
pte.set_writable(region.is_writable());
pte.set_cache_disabled(!region.vmo().m_allow_cpu_caching);
pte.set_write_through(!region.vmo().m_allow_cpu_caching);
} else {
pte.set_physical_page_base(0);
pte.set_present(false);
pte.set_writable(region.is_writable());
}
pte.set_user_allowed(user_allowed);
page_directory.flush(page_laddr);
#ifdef MM_DEBUG
dbgprintf("MM: >> map_region_at_address (PD=%x) '%s' L%x => P%x (@%p)\n", &page_directory, region.name().characters(), page_laddr, physical_page ? physical_page->paddr().get() : 0, physical_page.ptr());
#endif
}
}
bool MemoryManager::unmap_region(Region& region)
{
ASSERT(region.page_directory());
InterruptDisabler disabler;
for (size_t i = 0; i < region.page_count(); ++i) {
auto laddr = region.laddr().offset(i * PAGE_SIZE);
auto pte = ensure_pte(*region.page_directory(), laddr);
pte.set_physical_page_base(0);
pte.set_present(false);
pte.set_writable(false);
pte.set_user_allowed(false);
region.page_directory()->flush(laddr);
#ifdef MM_DEBUG
auto& physical_page = region.vmo().physical_pages()[region.first_page_index() + i];
dbgprintf("MM: >> Unmapped L%x => P%x <<\n", laddr, physical_page ? physical_page->paddr().get() : 0);
#endif
}
region.release_page_directory();
return true;
}
bool MemoryManager::map_region(Process& process, Region& region)
{
map_region_at_address(process.page_directory(), region, region.laddr(), true);
return true;
}
bool MemoryManager::validate_user_read(const Process& process, LinearAddress laddr) const
{
auto* region = region_from_laddr(process, laddr);
return region && region->is_readable();
}
bool MemoryManager::validate_user_write(const Process& process, LinearAddress laddr) const
{
auto* region = region_from_laddr(process, laddr);
return region && region->is_writable();
}
void MemoryManager::register_vmo(VMObject& vmo)
{
InterruptDisabler disabler;
m_vmos.set(&vmo);
}
void MemoryManager::unregister_vmo(VMObject& vmo)
{
InterruptDisabler disabler;
m_vmos.remove(&vmo);
}
void MemoryManager::register_region(Region& region)
{
InterruptDisabler disabler;
m_regions.set(&region);
}
void MemoryManager::unregister_region(Region& region)
{
InterruptDisabler disabler;
m_regions.remove(&region);
}
ProcessPagingScope::ProcessPagingScope(Process& process)
{
ASSERT(current);
MM.enter_process_paging_scope(process);
}
ProcessPagingScope::~ProcessPagingScope()
{
MM.enter_process_paging_scope(current->process());
}
KernelPagingScope::KernelPagingScope()
{
ASSERT(current);
MM.enter_kernel_paging_scope();
}
KernelPagingScope::~KernelPagingScope()
{
MM.enter_process_paging_scope(current->process());
}

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#pragma once
#include "types.h"
#include "i386.h"
#include <AK/Bitmap.h>
#include <AK/ByteBuffer.h>
#include <AK/Retainable.h>
#include <AK/RetainPtr.h>
#include <AK/Vector.h>
#include <AK/HashTable.h>
#include <AK/AKString.h>
#include <AK/Badge.h>
#include <AK/Weakable.h>
#include <Kernel/VM/PhysicalPage.h>
#include <Kernel/VM/Region.h>
#include <Kernel/VM/VMObject.h>
#include <Kernel/FileSystem/InodeIdentifier.h>
#define PAGE_ROUND_UP(x) ((((dword)(x)) + PAGE_SIZE-1) & (~(PAGE_SIZE-1)))
class SynthFSInode;
enum class PageFaultResponse {
ShouldCrash,
Continue,
};
#define MM MemoryManager::the()
class MemoryManager {
AK_MAKE_ETERNAL
friend class PageDirectory;
friend class PhysicalPage;
friend class Region;
friend class VMObject;
friend ByteBuffer procfs$mm(InodeIdentifier);
friend ByteBuffer procfs$memstat(InodeIdentifier);
public:
[[gnu::pure]] static MemoryManager& the();
static void initialize();
PageFaultResponse handle_page_fault(const PageFault&);
bool map_region(Process&, Region&);
bool unmap_region(Region&);
void populate_page_directory(PageDirectory&);
void enter_process_paging_scope(Process&);
void enter_kernel_paging_scope();
bool validate_user_read(const Process&, LinearAddress) const;
bool validate_user_write(const Process&, LinearAddress) const;
enum class ShouldZeroFill { No, Yes };
RetainPtr<PhysicalPage> allocate_physical_page(ShouldZeroFill);
RetainPtr<PhysicalPage> allocate_supervisor_physical_page();
void remap_region(PageDirectory&, Region&);
size_t ram_size() const { return m_ram_size; }
int user_physical_pages_in_existence() const { return s_user_physical_pages_in_existence; }
int super_physical_pages_in_existence() const { return s_super_physical_pages_in_existence; }
void map_for_kernel(LinearAddress, PhysicalAddress);
private:
MemoryManager();
~MemoryManager();
void register_vmo(VMObject&);
void unregister_vmo(VMObject&);
void register_region(Region&);
void unregister_region(Region&);
void map_region_at_address(PageDirectory&, Region&, LinearAddress, bool user_accessible);
void remap_region_page(Region&, unsigned page_index_in_region, bool user_allowed);
void initialize_paging();
void flush_entire_tlb();
void flush_tlb(LinearAddress);
RetainPtr<PhysicalPage> allocate_page_table(PageDirectory&, unsigned index);
void map_protected(LinearAddress, size_t length);
void create_identity_mapping(PageDirectory&, LinearAddress, size_t length);
void remove_identity_mapping(PageDirectory&, LinearAddress, size_t);
static Region* region_from_laddr(Process&, LinearAddress);
static const Region* region_from_laddr(const Process&, LinearAddress);
bool copy_on_write(Region&, unsigned page_index_in_region);
bool page_in_from_inode(Region&, unsigned page_index_in_region);
bool zero_page(Region& region, unsigned page_index_in_region);
byte* quickmap_page(PhysicalPage&);
void unquickmap_page();
PageDirectory& kernel_page_directory() { return *m_kernel_page_directory; }
struct PageDirectoryEntry {
explicit PageDirectoryEntry(dword* pde) : m_pde(pde) { }
dword* page_table_base() { return reinterpret_cast<dword*>(raw() & 0xfffff000u); }
void set_page_table_base(dword value)
{
*m_pde &= 0xfff;
*m_pde |= value & 0xfffff000;
}
dword raw() const { return *m_pde; }
dword* ptr() { return m_pde; }
enum Flags {
Present = 1 << 0,
ReadWrite = 1 << 1,
UserSupervisor = 1 << 2,
WriteThrough = 1 << 3,
CacheDisabled = 1 << 4,
};
bool is_present() const { return raw() & Present; }
void set_present(bool b) { set_bit(Present, b); }
bool is_user_allowed() const { return raw() & UserSupervisor; }
void set_user_allowed(bool b) { set_bit(UserSupervisor, b); }
bool is_writable() const { return raw() & ReadWrite; }
void set_writable(bool b) { set_bit(ReadWrite, b); }
bool is_write_through() const { return raw() & WriteThrough; }
void set_write_through(bool b) { set_bit(WriteThrough, b); }
bool is_cache_disabled() const { return raw() & CacheDisabled; }
void set_cache_disabled(bool b) { set_bit(CacheDisabled, b); }
void set_bit(byte bit, bool value)
{
if (value)
*m_pde |= bit;
else
*m_pde &= ~bit;
}
dword* m_pde;
};
struct PageTableEntry {
explicit PageTableEntry(dword* pte) : m_pte(pte) { }
dword* physical_page_base() { return reinterpret_cast<dword*>(raw() & 0xfffff000u); }
void set_physical_page_base(dword value)
{
*m_pte &= 0xfffu;
*m_pte |= value & 0xfffff000u;
}
dword raw() const { return *m_pte; }
dword* ptr() { return m_pte; }
enum Flags {
Present = 1 << 0,
ReadWrite = 1 << 1,
UserSupervisor = 1 << 2,
WriteThrough = 1 << 3,
CacheDisabled = 1 << 4,
};
bool is_present() const { return raw() & Present; }
void set_present(bool b) { set_bit(Present, b); }
bool is_user_allowed() const { return raw() & UserSupervisor; }
void set_user_allowed(bool b) { set_bit(UserSupervisor, b); }
bool is_writable() const { return raw() & ReadWrite; }
void set_writable(bool b) { set_bit(ReadWrite, b); }
bool is_write_through() const { return raw() & WriteThrough; }
void set_write_through(bool b) { set_bit(WriteThrough, b); }
bool is_cache_disabled() const { return raw() & CacheDisabled; }
void set_cache_disabled(bool b) { set_bit(CacheDisabled, b); }
void set_bit(byte bit, bool value)
{
if (value)
*m_pte |= bit;
else
*m_pte &= ~bit;
}
dword* m_pte;
};
static unsigned s_user_physical_pages_in_existence;
static unsigned s_super_physical_pages_in_existence;
PageTableEntry ensure_pte(PageDirectory&, LinearAddress);
RetainPtr<PageDirectory> m_kernel_page_directory;
dword* m_page_table_zero;
LinearAddress m_quickmap_addr;
Vector<Retained<PhysicalPage>> m_free_physical_pages;
Vector<Retained<PhysicalPage>> m_free_supervisor_physical_pages;
HashTable<VMObject*> m_vmos;
HashTable<Region*> m_regions;
size_t m_ram_size { 0 };
bool m_quickmap_in_use { false };
};
struct ProcessPagingScope {
ProcessPagingScope(Process&);
~ProcessPagingScope();
};
struct KernelPagingScope {
KernelPagingScope();
~KernelPagingScope();
};

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#include <Kernel/VM/PageDirectory.h>
#include <Kernel/VM/MemoryManager.h>
#include <Kernel/Process.h>
#include <Kernel/Thread.h>
PageDirectory::PageDirectory(PhysicalAddress paddr)
{
m_directory_page = PhysicalPage::create_eternal(paddr, true);
}
PageDirectory::PageDirectory()
{
MM.populate_page_directory(*this);
}
PageDirectory::~PageDirectory()
{
#ifdef MM_DEBUG
dbgprintf("MM: ~PageDirectory K%x\n", this);
#endif
}
void PageDirectory::flush(LinearAddress laddr)
{
#ifdef MM_DEBUG
dbgprintf("MM: Flush page L%x\n", laddr.get());
#endif
if (!current)
return;
if (&current->process().page_directory() == this)
MM.flush_tlb(laddr);
}

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#pragma once
#include <Kernel/VM/PhysicalPage.h>
#include <AK/HashMap.h>
#include <AK/Retainable.h>
#include <AK/RetainPtr.h>
class PageDirectory : public Retainable<PageDirectory> {
friend class MemoryManager;
public:
static Retained<PageDirectory> create() { return adopt(*new PageDirectory); }
static Retained<PageDirectory> create_at_fixed_address(PhysicalAddress paddr) { return adopt(*new PageDirectory(paddr)); }
~PageDirectory();
dword cr3() const { return m_directory_page->paddr().get(); }
dword* entries() { return reinterpret_cast<dword*>(cr3()); }
void flush(LinearAddress);
private:
PageDirectory();
explicit PageDirectory(PhysicalAddress);
RetainPtr<PhysicalPage> m_directory_page;
HashMap<unsigned, RetainPtr<PhysicalPage>> m_physical_pages;
};

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#include <Kernel/VM/PhysicalPage.h>
#include <Kernel/VM/MemoryManager.h>
#include <Kernel/kmalloc.h>
Retained<PhysicalPage> PhysicalPage::create_eternal(PhysicalAddress paddr, bool supervisor)
{
void* slot = kmalloc_eternal(sizeof(PhysicalPage));
new (slot) PhysicalPage(paddr, supervisor);
return adopt(*(PhysicalPage*)slot);
}
Retained<PhysicalPage> PhysicalPage::create(PhysicalAddress paddr, bool supervisor)
{
void* slot = kmalloc(sizeof(PhysicalPage));
new (slot) PhysicalPage(paddr, supervisor, false);
return adopt(*(PhysicalPage*)slot);
}
PhysicalPage::PhysicalPage(PhysicalAddress paddr, bool supervisor, bool may_return_to_freelist)
: m_may_return_to_freelist(may_return_to_freelist)
, m_supervisor(supervisor)
, m_paddr(paddr)
{
if (supervisor)
++MemoryManager::s_super_physical_pages_in_existence;
else
++MemoryManager::s_user_physical_pages_in_existence;
}
void PhysicalPage::return_to_freelist()
{
ASSERT((paddr().get() & ~PAGE_MASK) == 0);
InterruptDisabler disabler;
m_retain_count = 1;
if (m_supervisor)
MM.m_free_supervisor_physical_pages.append(adopt(*this));
else
MM.m_free_physical_pages.append(adopt(*this));
#ifdef MM_DEBUG
dbgprintf("MM: P%x released to freelist\n", m_paddr.get());
#endif
}

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#pragma once
#include <Kernel/Assertions.h>
#include <Kernel/types.h>
#include <AK/Retained.h>
class PhysicalPage {
friend class MemoryManager;
friend class PageDirectory;
friend class VMObject;
public:
PhysicalAddress paddr() const { return m_paddr; }
void retain()
{
ASSERT(m_retain_count);
++m_retain_count;
}
void release()
{
ASSERT(m_retain_count);
if (!--m_retain_count) {
if (m_may_return_to_freelist)
return_to_freelist();
else
delete this;
}
}
static Retained<PhysicalPage> create_eternal(PhysicalAddress, bool supervisor);
static Retained<PhysicalPage> create(PhysicalAddress, bool supervisor);
word retain_count() const { return m_retain_count; }
private:
PhysicalPage(PhysicalAddress paddr, bool supervisor, bool may_return_to_freelist = true);
~PhysicalPage() { }
void return_to_freelist();
word m_retain_count { 1 };
bool m_may_return_to_freelist { true };
bool m_supervisor { false };
PhysicalAddress m_paddr;
};

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#include <Kernel/VM/Region.h>
#include <Kernel/VM/VMObject.h>
#include <Kernel/VM/MemoryManager.h>
#include <Kernel/Process.h>
#include <Kernel/Thread.h>
Region::Region(LinearAddress a, size_t s, String&& n, bool r, bool w, bool cow)
: m_laddr(a)
, m_size(s)
, m_vmo(VMObject::create_anonymous(s))
, m_name(move(n))
, m_readable(r)
, m_writable(w)
, m_cow_map(Bitmap::create(m_vmo->page_count(), cow))
{
m_vmo->set_name(m_name);
MM.register_region(*this);
}
Region::Region(LinearAddress a, size_t s, RetainPtr<Inode>&& inode, String&& n, bool r, bool w)
: m_laddr(a)
, m_size(s)
, m_vmo(VMObject::create_file_backed(move(inode)))
, m_name(move(n))
, m_readable(r)
, m_writable(w)
, m_cow_map(Bitmap::create(m_vmo->page_count()))
{
MM.register_region(*this);
}
Region::Region(LinearAddress a, size_t s, Retained<VMObject>&& vmo, size_t offset_in_vmo, String&& n, bool r, bool w, bool cow)
: m_laddr(a)
, m_size(s)
, m_offset_in_vmo(offset_in_vmo)
, m_vmo(move(vmo))
, m_name(move(n))
, m_readable(r)
, m_writable(w)
, m_cow_map(Bitmap::create(m_vmo->page_count(), cow))
{
MM.register_region(*this);
}
Region::~Region()
{
if (m_page_directory) {
MM.unmap_region(*this);
ASSERT(!m_page_directory);
}
MM.unregister_region(*this);
}
bool Region::page_in()
{
ASSERT(m_page_directory);
ASSERT(!vmo().is_anonymous());
ASSERT(vmo().inode());
#ifdef MM_DEBUG
dbgprintf("MM: page_in %u pages\n", page_count());
#endif
for (size_t i = 0; i < page_count(); ++i) {
auto& vmo_page = vmo().physical_pages()[first_page_index() + i];
if (vmo_page.is_null()) {
bool success = MM.page_in_from_inode(*this, i);
if (!success)
return false;
}
MM.remap_region_page(*this, i, true);
}
return true;
}
Retained<Region> Region::clone()
{
ASSERT(current);
if (m_shared || (m_readable && !m_writable)) {
#ifdef MM_DEBUG
dbgprintf("%s<%u> Region::clone(): sharing %s (L%x)\n",
current->process().name().characters(),
current->pid(),
m_name.characters(),
laddr().get());
#endif
// Create a new region backed by the same VMObject.
return adopt(*new Region(laddr(), size(), m_vmo.copy_ref(), m_offset_in_vmo, String(m_name), m_readable, m_writable));
}
#ifdef MM_DEBUG
dbgprintf("%s<%u> Region::clone(): cowing %s (L%x)\n",
current->process().name().characters(),
current->pid(),
m_name.characters(),
laddr().get());
#endif
// Set up a COW region. The parent (this) region becomes COW as well!
for (size_t i = 0; i < page_count(); ++i)
m_cow_map.set(i, true);
MM.remap_region(current->process().page_directory(), *this);
return adopt(*new Region(laddr(), size(), m_vmo->clone(), m_offset_in_vmo, String(m_name), m_readable, m_writable, true));
}
int Region::commit()
{
InterruptDisabler disabler;
#ifdef MM_DEBUG
dbgprintf("MM: commit %u pages in Region %p (VMO=%p) at L%x\n", vmo().page_count(), this, &vmo(), laddr().get());
#endif
for (size_t i = first_page_index(); i <= last_page_index(); ++i) {
if (!vmo().physical_pages()[i].is_null())
continue;
auto physical_page = MM.allocate_physical_page(MemoryManager::ShouldZeroFill::Yes);
if (!physical_page) {
kprintf("MM: commit was unable to allocate a physical page\n");
return -ENOMEM;
}
vmo().physical_pages()[i] = move(physical_page);
MM.remap_region_page(*this, i, true);
}
return 0;
}
size_t Region::amount_resident() const
{
size_t bytes = 0;
for (size_t i = 0; i < page_count(); ++i) {
if (m_vmo->physical_pages()[first_page_index() + i])
bytes += PAGE_SIZE;
}
return bytes;
}
size_t Region::amount_shared() const
{
size_t bytes = 0;
for (size_t i = 0; i < page_count(); ++i) {
auto& physical_page = m_vmo->physical_pages()[first_page_index() + i];
if (physical_page && physical_page->retain_count() > 1)
bytes += PAGE_SIZE;
}
return bytes;
}

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#pragma once
#include <AK/AKString.h>
#include <AK/Bitmap.h>
#include <Kernel/VM/PageDirectory.h>
class Inode;
class VMObject;
class Region : public Retainable<Region> {
friend class MemoryManager;
public:
Region(LinearAddress, size_t, String&&, bool r, bool w, bool cow = false);
Region(LinearAddress, size_t, Retained<VMObject>&&, size_t offset_in_vmo, String&&, bool r, bool w, bool cow = false);
Region(LinearAddress, size_t, RetainPtr<Inode>&&, String&&, bool r, bool w);
~Region();
LinearAddress laddr() const { return m_laddr; }
size_t size() const { return m_size; }
bool is_readable() const { return m_readable; }
bool is_writable() const { return m_writable; }
String name() const { return m_name; }
void set_name(String&& name) { m_name = move(name); }
const VMObject& vmo() const { return *m_vmo; }
VMObject& vmo() { return *m_vmo; }
bool is_shared() const { return m_shared; }
void set_shared(bool shared) { m_shared = shared; }
bool is_bitmap() const { return m_is_bitmap; }
void set_is_bitmap(bool b) { m_is_bitmap = b; }
Retained<Region> clone();
bool contains(LinearAddress laddr) const
{
return laddr >= m_laddr && laddr < m_laddr.offset(size());
}
unsigned page_index_from_address(LinearAddress laddr) const
{
return (laddr - m_laddr).get() / PAGE_SIZE;
}
size_t first_page_index() const
{
return m_offset_in_vmo / PAGE_SIZE;
}
size_t last_page_index() const
{
return (first_page_index() + page_count()) - 1;
}
size_t page_count() const
{
return m_size / PAGE_SIZE;
}
bool page_in();
int commit();
size_t amount_resident() const;
size_t amount_shared() const;
PageDirectory* page_directory() { return m_page_directory.ptr(); }
void set_page_directory(PageDirectory& page_directory)
{
ASSERT(!m_page_directory || m_page_directory.ptr() == &page_directory);
m_page_directory = page_directory;
}
void release_page_directory()
{
ASSERT(m_page_directory);
m_page_directory.clear();
}
const Bitmap& cow_map() const { return m_cow_map; }
void set_writable(bool b) { m_writable = b; }
private:
RetainPtr<PageDirectory> m_page_directory;
LinearAddress m_laddr;
size_t m_size { 0 };
size_t m_offset_in_vmo { 0 };
Retained<VMObject> m_vmo;
String m_name;
bool m_readable { true };
bool m_writable { true };
bool m_shared { false };
bool m_is_bitmap { false };
Bitmap m_cow_map;
};

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#include <Kernel/VM/VMObject.h>
#include <Kernel/VM/MemoryManager.h>
#include <FileSystem/FileSystem.h>
Retained<VMObject> VMObject::create_file_backed(RetainPtr<Inode>&& inode)
{
InterruptDisabler disabler;
if (inode->vmo())
return *inode->vmo();
auto vmo = adopt(*new VMObject(move(inode)));
vmo->inode()->set_vmo(*vmo);
return vmo;
}
Retained<VMObject> VMObject::create_anonymous(size_t size)
{
size = ceil_div(size, PAGE_SIZE) * PAGE_SIZE;
return adopt(*new VMObject(size));
}
Retained<VMObject> VMObject::create_for_physical_range(PhysicalAddress paddr, size_t size)
{
size = ceil_div(size, PAGE_SIZE) * PAGE_SIZE;
auto vmo = adopt(*new VMObject(paddr, size));
vmo->m_allow_cpu_caching = false;
return vmo;
}
Retained<VMObject> VMObject::clone()
{
return adopt(*new VMObject(*this));
}
VMObject::VMObject(VMObject& other)
: m_name(other.m_name)
, m_anonymous(other.m_anonymous)
, m_inode_offset(other.m_inode_offset)
, m_size(other.m_size)
, m_inode(other.m_inode)
, m_physical_pages(other.m_physical_pages)
{
MM.register_vmo(*this);
}
VMObject::VMObject(size_t size)
: m_anonymous(true)
, m_size(size)
{
MM.register_vmo(*this);
m_physical_pages.resize(page_count());
}
VMObject::VMObject(PhysicalAddress paddr, size_t size)
: m_anonymous(true)
, m_size(size)
{
MM.register_vmo(*this);
for (size_t i = 0; i < size; i += PAGE_SIZE) {
m_physical_pages.append(PhysicalPage::create(paddr.offset(i), false));
}
ASSERT(m_physical_pages.size() == page_count());
}
VMObject::VMObject(RetainPtr<Inode>&& inode)
: m_inode(move(inode))
{
ASSERT(m_inode);
m_size = ceil_div(m_inode->size(), PAGE_SIZE) * PAGE_SIZE;
m_physical_pages.resize(page_count());
MM.register_vmo(*this);
}
VMObject::~VMObject()
{
if (m_inode)
ASSERT(m_inode->vmo() == this);
MM.unregister_vmo(*this);
}
template<typename Callback>
void VMObject::for_each_region(Callback callback)
{
// FIXME: Figure out a better data structure so we don't have to walk every single region every time an inode changes.
// Perhaps VMObject could have a Vector<Region*> with all of his mappers?
for (auto* region : MM.m_regions) {
if (&region->vmo() == this)
callback(*region);
}
}
void VMObject::inode_size_changed(Badge<Inode>, size_t old_size, size_t new_size)
{
(void)old_size;
InterruptDisabler disabler;
size_t old_page_count = page_count();
m_size = new_size;
if (page_count() > old_page_count) {
// Add null pages and let the fault handler page these in when that day comes.
for (size_t i = old_page_count; i < page_count(); ++i)
m_physical_pages.append(nullptr);
} else {
// Prune the no-longer valid pages. I'm not sure this is actually correct behavior.
for (size_t i = page_count(); i < old_page_count; ++i)
m_physical_pages.take_last();
}
// FIXME: Consolidate with inode_contents_changed() so we only do a single walk.
for_each_region([] (Region& region) {
ASSERT(region.page_directory());
MM.remap_region(*region.page_directory(), region);
});
}
void VMObject::inode_contents_changed(Badge<Inode>, off_t offset, ssize_t size, const byte* data)
{
(void)size;
(void)data;
InterruptDisabler disabler;
ASSERT(offset >= 0);
// FIXME: Only invalidate the parts that actually changed.
for (auto& physical_page : m_physical_pages)
physical_page = nullptr;
#if 0
size_t current_offset = offset;
size_t remaining_bytes = size;
const byte* data_ptr = data;
auto to_page_index = [] (size_t offset) -> size_t {
return offset / PAGE_SIZE;
};
if (current_offset & PAGE_MASK) {
size_t page_index = to_page_index(current_offset);
size_t bytes_to_copy = min(size, PAGE_SIZE - (current_offset & PAGE_MASK));
if (m_physical_pages[page_index]) {
auto* ptr = MM.quickmap_page(*m_physical_pages[page_index]);
memcpy(ptr, data_ptr, bytes_to_copy);
MM.unquickmap_page();
}
current_offset += bytes_to_copy;
data += bytes_to_copy;
remaining_bytes -= bytes_to_copy;
}
for (size_t page_index = to_page_index(current_offset); page_index < m_physical_pages.size(); ++page_index) {
size_t bytes_to_copy = PAGE_SIZE - (current_offset & PAGE_MASK);
if (m_physical_pages[page_index]) {
auto* ptr = MM.quickmap_page(*m_physical_pages[page_index]);
memcpy(ptr, data_ptr, bytes_to_copy);
MM.unquickmap_page();
}
current_offset += bytes_to_copy;
data += bytes_to_copy;
}
#endif
// FIXME: Consolidate with inode_size_changed() so we only do a single walk.
for_each_region([] (Region& region) {
ASSERT(region.page_directory());
MM.remap_region(*region.page_directory(), region);
});
}

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#pragma once
#include <AK/Badge.h>
#include <AK/Retainable.h>
#include <AK/Weakable.h>
#include <AK/RetainPtr.h>
#include <AK/Vector.h>
#include <AK/AKString.h>
#include <Kernel/Lock.h>
class Inode;
class PhysicalPage;
class VMObject : public Retainable<VMObject>, public Weakable<VMObject> {
friend class MemoryManager;
public:
static Retained<VMObject> create_file_backed(RetainPtr<Inode>&&);
static Retained<VMObject> create_anonymous(size_t);
static Retained<VMObject> create_for_physical_range(PhysicalAddress, size_t);
Retained<VMObject> clone();
~VMObject();
bool is_anonymous() const { return m_anonymous; }
Inode* inode() { return m_inode.ptr(); }
const Inode* inode() const { return m_inode.ptr(); }
size_t inode_offset() const { return m_inode_offset; }
String name() const { return m_name; }
void set_name(const String& name) { m_name = name; }
size_t page_count() const { return m_size / PAGE_SIZE; }
const Vector<RetainPtr<PhysicalPage>>& physical_pages() const { return m_physical_pages; }
Vector<RetainPtr<PhysicalPage>>& physical_pages() { return m_physical_pages; }
void inode_contents_changed(Badge<Inode>, off_t, ssize_t, const byte*);
void inode_size_changed(Badge<Inode>, size_t old_size, size_t new_size);
size_t size() const { return m_size; }
private:
VMObject(RetainPtr<Inode>&&);
explicit VMObject(VMObject&);
explicit VMObject(size_t);
VMObject(PhysicalAddress, size_t);
template<typename Callback> void for_each_region(Callback);
String m_name;
bool m_anonymous { false };
off_t m_inode_offset { 0 };
size_t m_size { 0 };
bool m_allow_cpu_caching { true };
RetainPtr<Inode> m_inode;
Vector<RetainPtr<PhysicalPage>> m_physical_pages;
Lock m_paging_lock;
};