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ladybird/Kernel/Memory/MemoryManager.cpp
Andreas Kling a154faebb7 Kernel: Use NonnullRefPtr<PhysicalPage> in PageDirectory::m_page_tables 
We don't care to store null page pointers in the page table map.
2021-08-15 16:53:03 +02:00

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/*
* Copyright (c) 2018-2021, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/Assertions.h>
#include <AK/Memory.h>
#include <AK/StringView.h>
#include <Kernel/BootInfo.h>
#include <Kernel/CMOS.h>
#include <Kernel/FileSystem/Inode.h>
#include <Kernel/Heap/kmalloc.h>
#include <Kernel/Memory/AnonymousVMObject.h>
#include <Kernel/Memory/MemoryManager.h>
#include <Kernel/Memory/PageDirectory.h>
#include <Kernel/Memory/PhysicalRegion.h>
#include <Kernel/Memory/SharedInodeVMObject.h>
#include <Kernel/Multiboot.h>
#include <Kernel/Panic.h>
#include <Kernel/Process.h>
#include <Kernel/Sections.h>
#include <Kernel/StdLib.h>
extern u8 start_of_kernel_image[];
extern u8 end_of_kernel_image[];
extern u8 start_of_kernel_text[];
extern u8 start_of_kernel_data[];
extern u8 end_of_kernel_bss[];
extern u8 start_of_ro_after_init[];
extern u8 end_of_ro_after_init[];
extern u8 start_of_unmap_after_init[];
extern u8 end_of_unmap_after_init[];
extern u8 start_of_kernel_ksyms[];
extern u8 end_of_kernel_ksyms[];
extern multiboot_module_entry_t multiboot_copy_boot_modules_array[16];
extern size_t multiboot_copy_boot_modules_count;
// Treat the super pages as logically separate from .bss
__attribute__((section(".super_pages"))) static u8 super_pages[1 * MiB];
namespace Kernel::Memory {
// NOTE: We can NOT use Singleton for this class, because
// MemoryManager::initialize is called *before* global constructors are
// run. If we do, then Singleton would get re-initialized, causing
// the memory manager to be initialized twice!
static MemoryManager* s_the;
RecursiveSpinLock s_mm_lock;
MemoryManager& MemoryManager::the()
{
return *s_the;
}
bool MemoryManager::is_initialized()
{
return s_the != nullptr;
}
UNMAP_AFTER_INIT MemoryManager::MemoryManager()
{
s_the = this;
ScopedSpinLock lock(s_mm_lock);
parse_memory_map();
write_cr3(kernel_page_directory().cr3());
protect_kernel_image();
// We're temporarily "committing" to two pages that we need to allocate below
auto committed_pages = commit_user_physical_pages(2);
m_shared_zero_page = committed_pages->take_one();
// We're wasting a page here, we just need a special tag (physical
// address) so that we know when we need to lazily allocate a page
// that we should be drawing this page from the committed pool rather
// than potentially failing if no pages are available anymore.
// By using a tag we don't have to query the VMObject for every page
// whether it was committed or not
m_lazy_committed_page = committed_pages->take_one();
}
UNMAP_AFTER_INIT MemoryManager::~MemoryManager()
{
}
UNMAP_AFTER_INIT void MemoryManager::protect_kernel_image()
{
ScopedSpinLock page_lock(kernel_page_directory().get_lock());
// Disable writing to the kernel text and rodata segments.
for (auto i = start_of_kernel_text; i < start_of_kernel_data; i += PAGE_SIZE) {
auto& pte = *ensure_pte(kernel_page_directory(), VirtualAddress(i));
pte.set_writable(false);
}
if (Processor::current().has_feature(CPUFeature::NX)) {
// Disable execution of the kernel data, bss and heap segments.
for (auto i = start_of_kernel_data; i < end_of_kernel_image; i += PAGE_SIZE) {
auto& pte = *ensure_pte(kernel_page_directory(), VirtualAddress(i));
pte.set_execute_disabled(true);
}
}
}
UNMAP_AFTER_INIT void MemoryManager::protect_readonly_after_init_memory()
{
ScopedSpinLock page_lock(kernel_page_directory().get_lock());
ScopedSpinLock mm_lock(s_mm_lock);
// Disable writing to the .ro_after_init section
for (auto i = (FlatPtr)&start_of_ro_after_init; i < (FlatPtr)&end_of_ro_after_init; i += PAGE_SIZE) {
auto& pte = *ensure_pte(kernel_page_directory(), VirtualAddress(i));
pte.set_writable(false);
flush_tlb(&kernel_page_directory(), VirtualAddress(i));
}
}
void MemoryManager::unmap_text_after_init()
{
ScopedSpinLock page_lock(kernel_page_directory().get_lock());
ScopedSpinLock mm_lock(s_mm_lock);
auto start = page_round_down((FlatPtr)&start_of_unmap_after_init);
auto end = page_round_up((FlatPtr)&end_of_unmap_after_init);
// Unmap the entire .unmap_after_init section
for (auto i = start; i < end; i += PAGE_SIZE) {
auto& pte = *ensure_pte(kernel_page_directory(), VirtualAddress(i));
pte.clear();
flush_tlb(&kernel_page_directory(), VirtualAddress(i));
}
dmesgln("Unmapped {} KiB of kernel text after init! :^)", (end - start) / KiB);
}
void MemoryManager::unmap_ksyms_after_init()
{
ScopedSpinLock mm_lock(s_mm_lock);
ScopedSpinLock page_lock(kernel_page_directory().get_lock());
auto start = page_round_down((FlatPtr)start_of_kernel_ksyms);
auto end = page_round_up((FlatPtr)end_of_kernel_ksyms);
// Unmap the entire .ksyms section
for (auto i = start; i < end; i += PAGE_SIZE) {
auto& pte = *ensure_pte(kernel_page_directory(), VirtualAddress(i));
pte.clear();
flush_tlb(&kernel_page_directory(), VirtualAddress(i));
}
dmesgln("Unmapped {} KiB of kernel symbols after init! :^)", (end - start) / KiB);
}
UNMAP_AFTER_INIT void MemoryManager::register_reserved_ranges()
{
VERIFY(!m_physical_memory_ranges.is_empty());
ContiguousReservedMemoryRange range;
for (auto& current_range : m_physical_memory_ranges) {
if (current_range.type != PhysicalMemoryRangeType::Reserved) {
if (range.start.is_null())
continue;
m_reserved_memory_ranges.append(ContiguousReservedMemoryRange { range.start, current_range.start.get() - range.start.get() });
range.start.set((FlatPtr) nullptr);
continue;
}
if (!range.start.is_null()) {
continue;
}
range.start = current_range.start;
}
if (m_physical_memory_ranges.last().type != PhysicalMemoryRangeType::Reserved)
return;
if (range.start.is_null())
return;
m_reserved_memory_ranges.append(ContiguousReservedMemoryRange { range.start, m_physical_memory_ranges.last().start.get() + m_physical_memory_ranges.last().length - range.start.get() });
}
bool MemoryManager::is_allowed_to_mmap_to_userspace(PhysicalAddress start_address, VirtualRange const& range) const
{
VERIFY(!m_reserved_memory_ranges.is_empty());
for (auto& current_range : m_reserved_memory_ranges) {
if (!(current_range.start <= start_address))
continue;
if (!(current_range.start.offset(current_range.length) > start_address))
continue;
if (current_range.length < range.size())
return false;
return true;
}
return false;
}
UNMAP_AFTER_INIT void MemoryManager::parse_memory_map()
{
// Register used memory regions that we know of.
m_used_memory_ranges.ensure_capacity(4);
m_used_memory_ranges.append(UsedMemoryRange { UsedMemoryRangeType::LowMemory, PhysicalAddress(0x00000000), PhysicalAddress(1 * MiB) });
m_used_memory_ranges.append(UsedMemoryRange { UsedMemoryRangeType::Prekernel, start_of_prekernel_image, end_of_prekernel_image });
m_used_memory_ranges.append(UsedMemoryRange { UsedMemoryRangeType::Kernel, PhysicalAddress(virtual_to_low_physical((FlatPtr)start_of_kernel_image)), PhysicalAddress(page_round_up(virtual_to_low_physical((FlatPtr)end_of_kernel_image))) });
if (multiboot_flags & 0x4) {
auto* bootmods_start = multiboot_copy_boot_modules_array;
auto* bootmods_end = bootmods_start + multiboot_copy_boot_modules_count;
for (auto* bootmod = bootmods_start; bootmod < bootmods_end; bootmod++) {
m_used_memory_ranges.append(UsedMemoryRange { UsedMemoryRangeType::BootModule, PhysicalAddress(bootmod->start), PhysicalAddress(bootmod->end) });
}
}
auto* mmap_begin = multiboot_memory_map;
auto* mmap_end = multiboot_memory_map + multiboot_memory_map_count;
struct ContiguousPhysicalVirtualRange {
PhysicalAddress lower;
PhysicalAddress upper;
};
Vector<ContiguousPhysicalVirtualRange> contiguous_physical_ranges;
for (auto* mmap = mmap_begin; mmap < mmap_end; mmap++) {
// We have to copy these onto the stack, because we take a reference to these when printing them out,
// and doing so on a packed struct field is UB.
auto address = mmap->addr;
auto length = mmap->len;
ArmedScopeGuard write_back_guard = [&]() {
mmap->addr = address;
mmap->len = length;
};
dmesgln("MM: Multiboot mmap: address={:p}, length={}, type={}", address, length, mmap->type);
auto start_address = PhysicalAddress(address);
switch (mmap->type) {
case (MULTIBOOT_MEMORY_AVAILABLE):
m_physical_memory_ranges.append(PhysicalMemoryRange { PhysicalMemoryRangeType::Usable, start_address, length });
break;
case (MULTIBOOT_MEMORY_RESERVED):
m_physical_memory_ranges.append(PhysicalMemoryRange { PhysicalMemoryRangeType::Reserved, start_address, length });
break;
case (MULTIBOOT_MEMORY_ACPI_RECLAIMABLE):
m_physical_memory_ranges.append(PhysicalMemoryRange { PhysicalMemoryRangeType::ACPI_Reclaimable, start_address, length });
break;
case (MULTIBOOT_MEMORY_NVS):
m_physical_memory_ranges.append(PhysicalMemoryRange { PhysicalMemoryRangeType::ACPI_NVS, start_address, length });
break;
case (MULTIBOOT_MEMORY_BADRAM):
dmesgln("MM: Warning, detected bad memory range!");
m_physical_memory_ranges.append(PhysicalMemoryRange { PhysicalMemoryRangeType::BadMemory, start_address, length });
break;
default:
dbgln("MM: Unknown range!");
m_physical_memory_ranges.append(PhysicalMemoryRange { PhysicalMemoryRangeType::Unknown, start_address, length });
break;
}
if (mmap->type != MULTIBOOT_MEMORY_AVAILABLE)
continue;
// Fix up unaligned memory regions.
auto diff = (FlatPtr)address % PAGE_SIZE;
if (diff != 0) {
dmesgln("MM: Got an unaligned physical_region from the bootloader; correcting {:p} by {} bytes", address, diff);
diff = PAGE_SIZE - diff;
address += diff;
length -= diff;
}
if ((length % PAGE_SIZE) != 0) {
dmesgln("MM: Got an unaligned physical_region from the bootloader; correcting length {} by {} bytes", length, length % PAGE_SIZE);
length -= length % PAGE_SIZE;
}
if (length < PAGE_SIZE) {
dmesgln("MM: Memory physical_region from bootloader is too small; we want >= {} bytes, but got {} bytes", PAGE_SIZE, length);
continue;
}
for (PhysicalSize page_base = address; page_base <= (address + length); page_base += PAGE_SIZE) {
auto addr = PhysicalAddress(page_base);
// Skip used memory ranges.
bool should_skip = false;
for (auto& used_range : m_used_memory_ranges) {
if (addr.get() >= used_range.start.get() && addr.get() <= used_range.end.get()) {
should_skip = true;
break;
}
}
if (should_skip)
continue;
if (contiguous_physical_ranges.is_empty() || contiguous_physical_ranges.last().upper.offset(PAGE_SIZE) != addr) {
contiguous_physical_ranges.append(ContiguousPhysicalVirtualRange {
.lower = addr,
.upper = addr,
});
} else {
contiguous_physical_ranges.last().upper = addr;
}
}
}
for (auto& range : contiguous_physical_ranges) {
m_user_physical_regions.append(PhysicalRegion::try_create(range.lower, range.upper).release_nonnull());
}
// Super pages are guaranteed to be in the first 16MB of physical memory
VERIFY(virtual_to_low_physical((FlatPtr)super_pages) + sizeof(super_pages) < 0x1000000);
// Append statically-allocated super physical physical_region.
m_super_physical_region = PhysicalRegion::try_create(
PhysicalAddress(virtual_to_low_physical(FlatPtr(super_pages))),
PhysicalAddress(virtual_to_low_physical(FlatPtr(super_pages + sizeof(super_pages)))));
VERIFY(m_super_physical_region);
m_system_memory_info.super_physical_pages += m_super_physical_region->size();
for (auto& region : m_user_physical_regions)
m_system_memory_info.user_physical_pages += region.size();
register_reserved_ranges();
for (auto& range : m_reserved_memory_ranges) {
dmesgln("MM: Contiguous reserved range from {}, length is {}", range.start, range.length);
}
initialize_physical_pages();
VERIFY(m_system_memory_info.super_physical_pages > 0);
VERIFY(m_system_memory_info.user_physical_pages > 0);
// We start out with no committed pages
m_system_memory_info.user_physical_pages_uncommitted = m_system_memory_info.user_physical_pages;
for (auto& used_range : m_used_memory_ranges) {
dmesgln("MM: {} range @ {} - {} (size {:#x})", UserMemoryRangeTypeNames[to_underlying(used_range.type)], used_range.start, used_range.end.offset(-1), used_range.end.as_ptr() - used_range.start.as_ptr());
}
dmesgln("MM: Super physical region: {} - {} (size {:#x})", m_super_physical_region->lower(), m_super_physical_region->upper().offset(-1), PAGE_SIZE * m_super_physical_region->size());
m_super_physical_region->initialize_zones();
for (auto& region : m_user_physical_regions) {
dmesgln("MM: User physical region: {} - {} (size {:#x})", region.lower(), region.upper().offset(-1), PAGE_SIZE * region.size());
region.initialize_zones();
}
}
UNMAP_AFTER_INIT void MemoryManager::initialize_physical_pages()
{
// We assume that the physical page range is contiguous and doesn't contain huge gaps!
PhysicalAddress highest_physical_address;
for (auto& range : m_used_memory_ranges) {
if (range.end.get() > highest_physical_address.get())
highest_physical_address = range.end;
}
for (auto& region : m_physical_memory_ranges) {
auto range_end = PhysicalAddress(region.start).offset(region.length);
if (range_end.get() > highest_physical_address.get())
highest_physical_address = range_end;
}
// Calculate how many total physical pages the array will have
m_physical_page_entries_count = PhysicalAddress::physical_page_index(highest_physical_address.get()) + 1;
VERIFY(m_physical_page_entries_count != 0);
VERIFY(!Checked<decltype(m_physical_page_entries_count)>::multiplication_would_overflow(m_physical_page_entries_count, sizeof(PhysicalPageEntry)));
// Calculate how many bytes the array will consume
auto physical_page_array_size = m_physical_page_entries_count * sizeof(PhysicalPageEntry);
auto physical_page_array_pages = page_round_up(physical_page_array_size) / PAGE_SIZE;
VERIFY(physical_page_array_pages * PAGE_SIZE >= physical_page_array_size);
// Calculate how many page tables we will need to be able to map them all
auto needed_page_table_count = (physical_page_array_pages + 512 - 1) / 512;
auto physical_page_array_pages_and_page_tables_count = physical_page_array_pages + needed_page_table_count;
// Now that we know how much memory we need for a contiguous array of PhysicalPage instances, find a memory region that can fit it
PhysicalRegion* found_region { nullptr };
Optional<size_t> found_region_index;
for (size_t i = 0; i < m_user_physical_regions.size(); ++i) {
auto& region = m_user_physical_regions[i];
if (region.size() >= physical_page_array_pages_and_page_tables_count) {
found_region = &region;
found_region_index = i;
break;
}
}
if (!found_region) {
dmesgln("MM: Need {} bytes for physical page management, but no memory region is large enough!", physical_page_array_pages_and_page_tables_count);
VERIFY_NOT_REACHED();
}
VERIFY(m_system_memory_info.user_physical_pages >= physical_page_array_pages_and_page_tables_count);
m_system_memory_info.user_physical_pages -= physical_page_array_pages_and_page_tables_count;
if (found_region->size() == physical_page_array_pages_and_page_tables_count) {
// We're stealing the entire region
m_physical_pages_region = m_user_physical_regions.take(*found_region_index);
} else {
m_physical_pages_region = found_region->try_take_pages_from_beginning(physical_page_array_pages_and_page_tables_count);
}
m_used_memory_ranges.append({ UsedMemoryRangeType::PhysicalPages, m_physical_pages_region->lower(), m_physical_pages_region->upper() });
// Create the bare page directory. This is not a fully constructed page directory and merely contains the allocators!
m_kernel_page_directory = PageDirectory::must_create_kernel_page_directory();
// Allocate a virtual address range for our array
auto range = m_kernel_page_directory->range_allocator().allocate_anywhere(physical_page_array_pages * PAGE_SIZE);
if (!range.has_value()) {
dmesgln("MM: Could not allocate {} bytes to map physical page array!", physical_page_array_pages * PAGE_SIZE);
VERIFY_NOT_REACHED();
}
// Now that we have our special m_physical_pages_region region with enough pages to hold the entire array
// try to map the entire region into kernel space so we always have it
// We can't use ensure_pte here because it would try to allocate a PhysicalPage and we don't have the array
// mapped yet so we can't create them
ScopedSpinLock lock(s_mm_lock);
// Create page tables at the beginning of m_physical_pages_region, followed by the PhysicalPageEntry array
auto page_tables_base = m_physical_pages_region->lower();
auto physical_page_array_base = page_tables_base.offset(needed_page_table_count * PAGE_SIZE);
auto physical_page_array_current_page = physical_page_array_base.get();
auto virtual_page_array_base = range.value().base().get();
auto virtual_page_array_current_page = virtual_page_array_base;
for (size_t pt_index = 0; pt_index < needed_page_table_count; pt_index++) {
auto virtual_page_base_for_this_pt = virtual_page_array_current_page;
auto pt_paddr = page_tables_base.offset(pt_index * PAGE_SIZE);
auto* pt = reinterpret_cast<PageTableEntry*>(quickmap_page(pt_paddr));
__builtin_memset(pt, 0, PAGE_SIZE);
for (size_t pte_index = 0; pte_index < PAGE_SIZE / sizeof(PageTableEntry); pte_index++) {
auto& pte = pt[pte_index];
pte.set_physical_page_base(physical_page_array_current_page);
pte.set_user_allowed(false);
pte.set_writable(true);
if (Processor::current().has_feature(CPUFeature::NX))
pte.set_execute_disabled(false);
pte.set_global(true);
pte.set_present(true);
physical_page_array_current_page += PAGE_SIZE;
virtual_page_array_current_page += PAGE_SIZE;
}
unquickmap_page();
// Hook the page table into the kernel page directory
u32 page_directory_index = (virtual_page_base_for_this_pt >> 21) & 0x1ff;
auto* pd = reinterpret_cast<PageDirectoryEntry*>(quickmap_page(boot_pd_kernel));
PageDirectoryEntry& pde = pd[page_directory_index];
VERIFY(!pde.is_present()); // Nothing should be using this PD yet
// We can't use ensure_pte quite yet!
pde.set_page_table_base(pt_paddr.get());
pde.set_user_allowed(false);
pde.set_present(true);
pde.set_writable(true);
pde.set_global(true);
unquickmap_page();
flush_tlb_local(VirtualAddress(virtual_page_base_for_this_pt));
}
// We now have the entire PhysicalPageEntry array mapped!
m_physical_page_entries = (PhysicalPageEntry*)range.value().base().get();
for (size_t i = 0; i < m_physical_page_entries_count; i++)
new (&m_physical_page_entries[i]) PageTableEntry();
// Now we should be able to allocate PhysicalPage instances,
// so finish setting up the kernel page directory
m_kernel_page_directory->allocate_kernel_directory();
// Now create legit PhysicalPage objects for the page tables we created, so that
// we can put them into kernel_page_directory().m_page_tables
auto& kernel_page_tables = kernel_page_directory().m_page_tables;
virtual_page_array_current_page = virtual_page_array_base;
for (size_t pt_index = 0; pt_index < needed_page_table_count; pt_index++) {
VERIFY(virtual_page_array_current_page <= range.value().end().get());
auto pt_paddr = page_tables_base.offset(pt_index * PAGE_SIZE);
auto physical_page_index = PhysicalAddress::physical_page_index(pt_paddr.get());
auto& physical_page_entry = m_physical_page_entries[physical_page_index];
auto physical_page = adopt_ref(*new (&physical_page_entry.allocated.physical_page) PhysicalPage(MayReturnToFreeList::No));
auto result = kernel_page_tables.set(virtual_page_array_current_page & ~0x1fffff, move(physical_page));
VERIFY(result == AK::HashSetResult::InsertedNewEntry);
virtual_page_array_current_page += (PAGE_SIZE / sizeof(PageTableEntry)) * PAGE_SIZE;
}
dmesgln("MM: Physical page entries: {}", range.value());
}
PhysicalPageEntry& MemoryManager::get_physical_page_entry(PhysicalAddress physical_address)
{
VERIFY(m_physical_page_entries);
auto physical_page_entry_index = PhysicalAddress::physical_page_index(physical_address.get());
VERIFY(physical_page_entry_index < m_physical_page_entries_count);
return m_physical_page_entries[physical_page_entry_index];
}
PhysicalAddress MemoryManager::get_physical_address(PhysicalPage const& physical_page)
{
PhysicalPageEntry const& physical_page_entry = *reinterpret_cast<PhysicalPageEntry const*>((u8 const*)&physical_page - __builtin_offsetof(PhysicalPageEntry, allocated.physical_page));
VERIFY(m_physical_page_entries);
size_t physical_page_entry_index = &physical_page_entry - m_physical_page_entries;
VERIFY(physical_page_entry_index < m_physical_page_entries_count);
return PhysicalAddress((PhysicalPtr)physical_page_entry_index * PAGE_SIZE);
}
PageTableEntry* MemoryManager::pte(PageDirectory& page_directory, VirtualAddress vaddr)
{
VERIFY_INTERRUPTS_DISABLED();
VERIFY(s_mm_lock.own_lock());
VERIFY(page_directory.get_lock().own_lock());
u32 page_directory_table_index = (vaddr.get() >> 30) & 0x1ff;
u32 page_directory_index = (vaddr.get() >> 21) & 0x1ff;
u32 page_table_index = (vaddr.get() >> 12) & 0x1ff;
auto* pd = quickmap_pd(const_cast<PageDirectory&>(page_directory), page_directory_table_index);
PageDirectoryEntry const& pde = pd[page_directory_index];
if (!pde.is_present())
return nullptr;
return &quickmap_pt(PhysicalAddress((FlatPtr)pde.page_table_base()))[page_table_index];
}
PageTableEntry* MemoryManager::ensure_pte(PageDirectory& page_directory, VirtualAddress vaddr)
{
VERIFY_INTERRUPTS_DISABLED();
VERIFY(s_mm_lock.own_lock());
VERIFY(page_directory.get_lock().own_lock());
u32 page_directory_table_index = (vaddr.get() >> 30) & 0x1ff;
u32 page_directory_index = (vaddr.get() >> 21) & 0x1ff;
u32 page_table_index = (vaddr.get() >> 12) & 0x1ff;
auto* pd = quickmap_pd(page_directory, page_directory_table_index);
PageDirectoryEntry& pde = pd[page_directory_index];
if (!pde.is_present()) {
bool did_purge = false;
auto page_table = allocate_user_physical_page(ShouldZeroFill::Yes, &did_purge);
if (!page_table) {
dbgln("MM: Unable to allocate page table to map {}", vaddr);
return nullptr;
}
if (did_purge) {
// If any memory had to be purged, ensure_pte may have been called as part
// of the purging process. So we need to re-map the pd in this case to ensure
// we're writing to the correct underlying physical page
pd = quickmap_pd(page_directory, page_directory_table_index);
VERIFY(&pde == &pd[page_directory_index]); // Sanity check
VERIFY(!pde.is_present()); // Should have not changed
}
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());
// Use page_directory_table_index and page_directory_index as key
// This allows us to release the page table entry when no longer needed
auto result = page_directory.m_page_tables.set(vaddr.get() & ~(FlatPtr)0x1fffff, page_table.release_nonnull());
// If you're hitting this VERIFY on x86_64 chances are a 64-bit pointer was truncated somewhere
VERIFY(result == AK::HashSetResult::InsertedNewEntry);
}
return &quickmap_pt(PhysicalAddress((FlatPtr)pde.page_table_base()))[page_table_index];
}
void MemoryManager::release_pte(PageDirectory& page_directory, VirtualAddress vaddr, bool is_last_release)
{
VERIFY_INTERRUPTS_DISABLED();
VERIFY(s_mm_lock.own_lock());
VERIFY(page_directory.get_lock().own_lock());
u32 page_directory_table_index = (vaddr.get() >> 30) & 0x1ff;
u32 page_directory_index = (vaddr.get() >> 21) & 0x1ff;
u32 page_table_index = (vaddr.get() >> 12) & 0x1ff;
auto* pd = quickmap_pd(page_directory, page_directory_table_index);
PageDirectoryEntry& pde = pd[page_directory_index];
if (pde.is_present()) {
auto* page_table = quickmap_pt(PhysicalAddress((FlatPtr)pde.page_table_base()));
auto& pte = page_table[page_table_index];
pte.clear();
if (is_last_release || page_table_index == 0x1ff) {
// If this is the last PTE in a region or the last PTE in a page table then
// check if we can also release the page table
bool all_clear = true;
for (u32 i = 0; i <= 0x1ff; i++) {
if (!page_table[i].is_null()) {
all_clear = false;
break;
}
}
if (all_clear) {
pde.clear();
auto result = page_directory.m_page_tables.remove(vaddr.get() & ~0x1fffff);
VERIFY(result);
}
}
}
}
UNMAP_AFTER_INIT void MemoryManager::initialize(u32 cpu)
{
ProcessorSpecific<MemoryManagerData>::initialize();
if (cpu == 0) {
new MemoryManager;
kmalloc_enable_expand();
}
}
Region* MemoryManager::kernel_region_from_vaddr(VirtualAddress vaddr)
{
ScopedSpinLock lock(s_mm_lock);
for (auto& region : MM.m_kernel_regions) {
if (region.contains(vaddr))
return &region;
}
return nullptr;
}
Region* MemoryManager::find_user_region_from_vaddr_no_lock(AddressSpace& space, VirtualAddress vaddr)
{
VERIFY(space.get_lock().own_lock());
return space.find_region_containing({ vaddr, 1 });
}
Region* MemoryManager::find_user_region_from_vaddr(AddressSpace& space, VirtualAddress vaddr)
{
ScopedSpinLock lock(space.get_lock());
return find_user_region_from_vaddr_no_lock(space, vaddr);
}
void MemoryManager::validate_syscall_preconditions(AddressSpace& space, RegisterState const& regs)
{
// We take the space lock once here and then use the no_lock variants
// to avoid excessive spinlock recursion in this extemely common path.
ScopedSpinLock lock(space.get_lock());
auto unlock_and_handle_crash = [&lock, &regs](const char* description, int signal) {
lock.unlock();
handle_crash(regs, description, signal);
};
{
VirtualAddress userspace_sp = VirtualAddress { regs.userspace_sp() };
if (!MM.validate_user_stack_no_lock(space, userspace_sp)) {
dbgln("Invalid stack pointer: {:p}", userspace_sp);
unlock_and_handle_crash("Bad stack on syscall entry", SIGSTKFLT);
}
}
{
VirtualAddress ip = VirtualAddress { regs.ip() };
auto* calling_region = MM.find_user_region_from_vaddr_no_lock(space, ip);
if (!calling_region) {
dbgln("Syscall from {:p} which has no associated region", ip);
unlock_and_handle_crash("Syscall from unknown region", SIGSEGV);
}
if (calling_region->is_writable()) {
dbgln("Syscall from writable memory at {:p}", ip);
unlock_and_handle_crash("Syscall from writable memory", SIGSEGV);
}
if (space.enforces_syscall_regions() && !calling_region->is_syscall_region()) {
dbgln("Syscall from non-syscall region");
unlock_and_handle_crash("Syscall from non-syscall region", SIGSEGV);
}
}
}
Region* MemoryManager::find_region_from_vaddr(VirtualAddress vaddr)
{
if (auto* region = kernel_region_from_vaddr(vaddr))
return region;
auto page_directory = PageDirectory::find_by_cr3(read_cr3());
if (!page_directory)
return nullptr;
VERIFY(page_directory->address_space());
return find_user_region_from_vaddr(*page_directory->address_space(), vaddr);
}
PageFaultResponse MemoryManager::handle_page_fault(PageFault const& fault)
{
VERIFY_INTERRUPTS_DISABLED();
if (Processor::current().in_irq()) {
dbgln("CPU[{}] BUG! Page fault while handling IRQ! code={}, vaddr={}, irq level: {}",
Processor::id(), fault.code(), fault.vaddr(), Processor::current().in_irq());
dump_kernel_regions();
return PageFaultResponse::ShouldCrash;
}
dbgln_if(PAGE_FAULT_DEBUG, "MM: CPU[{}] handle_page_fault({:#04x}) at {}", Processor::id(), fault.code(), fault.vaddr());
auto* region = find_region_from_vaddr(fault.vaddr());
if (!region) {
return PageFaultResponse::ShouldCrash;
}
return region->handle_fault(fault);
}
OwnPtr<Region> MemoryManager::allocate_contiguous_kernel_region(size_t size, StringView name, Region::Access access, Region::Cacheable cacheable)
{
VERIFY(!(size % PAGE_SIZE));
ScopedSpinLock lock(kernel_page_directory().get_lock());
auto range = kernel_page_directory().range_allocator().allocate_anywhere(size);
if (!range.has_value())
return {};
auto maybe_vmobject = AnonymousVMObject::try_create_physically_contiguous_with_size(size);
if (maybe_vmobject.is_error()) {
kernel_page_directory().range_allocator().deallocate(range.value());
// FIXME: Would be nice to be able to return a KResultOr from here.
return {};
}
return allocate_kernel_region_with_vmobject(range.value(), maybe_vmobject.release_value(), name, access, cacheable);
}
OwnPtr<Region> MemoryManager::allocate_kernel_region(size_t size, StringView name, Region::Access access, AllocationStrategy strategy, Region::Cacheable cacheable)
{
VERIFY(!(size % PAGE_SIZE));
auto maybe_vm_object = AnonymousVMObject::try_create_with_size(size, strategy);
if (maybe_vm_object.is_error())
return {};
ScopedSpinLock lock(kernel_page_directory().get_lock());
auto range = kernel_page_directory().range_allocator().allocate_anywhere(size);
if (!range.has_value())
return {};
return allocate_kernel_region_with_vmobject(range.value(), maybe_vm_object.release_value(), name, access, cacheable);
}
OwnPtr<Region> MemoryManager::allocate_kernel_region(PhysicalAddress paddr, size_t size, StringView name, Region::Access access, Region::Cacheable cacheable)
{
auto maybe_vm_object = AnonymousVMObject::try_create_for_physical_range(paddr, size);
if (maybe_vm_object.is_error())
return {};
VERIFY(!(size % PAGE_SIZE));
ScopedSpinLock lock(kernel_page_directory().get_lock());
auto range = kernel_page_directory().range_allocator().allocate_anywhere(size);
if (!range.has_value())
return {};
return allocate_kernel_region_with_vmobject(range.value(), maybe_vm_object.release_value(), name, access, cacheable);
}
OwnPtr<Region> MemoryManager::allocate_kernel_region_with_vmobject(VirtualRange const& range, VMObject& vmobject, StringView name, Region::Access access, Region::Cacheable cacheable)
{
auto maybe_region = Region::try_create_kernel_only(range, vmobject, 0, KString::try_create(name), access, cacheable);
if (maybe_region.is_error())
return {};
auto region = maybe_region.release_value();
region->map(kernel_page_directory());
return region;
}
OwnPtr<Region> MemoryManager::allocate_kernel_region_with_vmobject(VMObject& vmobject, size_t size, StringView name, Region::Access access, Region::Cacheable cacheable)
{
VERIFY(!(size % PAGE_SIZE));
ScopedSpinLock lock(kernel_page_directory().get_lock());
auto range = kernel_page_directory().range_allocator().allocate_anywhere(size);
if (!range.has_value())
return {};
return allocate_kernel_region_with_vmobject(range.value(), vmobject, name, access, cacheable);
}
Optional<CommittedPhysicalPageSet> MemoryManager::commit_user_physical_pages(size_t page_count)
{
VERIFY(page_count > 0);
ScopedSpinLock lock(s_mm_lock);
if (m_system_memory_info.user_physical_pages_uncommitted < page_count)
return {};
m_system_memory_info.user_physical_pages_uncommitted -= page_count;
m_system_memory_info.user_physical_pages_committed += page_count;
return CommittedPhysicalPageSet { {}, page_count };
}
void MemoryManager::uncommit_user_physical_pages(Badge<CommittedPhysicalPageSet>, size_t page_count)
{
VERIFY(page_count > 0);
ScopedSpinLock lock(s_mm_lock);
VERIFY(m_system_memory_info.user_physical_pages_committed >= page_count);
m_system_memory_info.user_physical_pages_uncommitted += page_count;
m_system_memory_info.user_physical_pages_committed -= page_count;
}
void MemoryManager::deallocate_physical_page(PhysicalAddress paddr)
{
ScopedSpinLock lock(s_mm_lock);
// Are we returning a user page?
for (auto& region : m_user_physical_regions) {
if (!region.contains(paddr))
continue;
region.return_page(paddr);
--m_system_memory_info.user_physical_pages_used;
// Always return pages to the uncommitted pool. Pages that were
// committed and allocated are only freed upon request. Once
// returned there is no guarantee being able to get them back.
++m_system_memory_info.user_physical_pages_uncommitted;
return;
}
// If it's not a user page, it should be a supervisor page.
if (!m_super_physical_region->contains(paddr))
PANIC("MM: deallocate_user_physical_page couldn't figure out region for page @ {}", paddr);
m_super_physical_region->return_page(paddr);
--m_system_memory_info.super_physical_pages_used;
}
RefPtr<PhysicalPage> MemoryManager::find_free_user_physical_page(bool committed)
{
VERIFY(s_mm_lock.is_locked());
RefPtr<PhysicalPage> page;
if (committed) {
// Draw from the committed pages pool. We should always have these pages available
VERIFY(m_system_memory_info.user_physical_pages_committed > 0);
m_system_memory_info.user_physical_pages_committed--;
} else {
// We need to make sure we don't touch pages that we have committed to
if (m_system_memory_info.user_physical_pages_uncommitted == 0)
return {};
m_system_memory_info.user_physical_pages_uncommitted--;
}
for (auto& region : m_user_physical_regions) {
page = region.take_free_page();
if (!page.is_null()) {
++m_system_memory_info.user_physical_pages_used;
break;
}
}
VERIFY(!committed || !page.is_null());
return page;
}
NonnullRefPtr<PhysicalPage> MemoryManager::allocate_committed_user_physical_page(Badge<CommittedPhysicalPageSet>, ShouldZeroFill should_zero_fill)
{
ScopedSpinLock lock(s_mm_lock);
auto page = find_free_user_physical_page(true);
if (should_zero_fill == ShouldZeroFill::Yes) {
auto* ptr = quickmap_page(*page);
memset(ptr, 0, PAGE_SIZE);
unquickmap_page();
}
return page.release_nonnull();
}
RefPtr<PhysicalPage> MemoryManager::allocate_user_physical_page(ShouldZeroFill should_zero_fill, bool* did_purge)
{
ScopedSpinLock lock(s_mm_lock);
auto page = find_free_user_physical_page(false);
bool purged_pages = false;
if (!page) {
// We didn't have a single free physical page. Let's try to free something up!
// First, we look for a purgeable VMObject in the volatile state.
for_each_vmobject([&](auto& vmobject) {
if (!vmobject.is_anonymous())
return IterationDecision::Continue;
auto& anonymous_vmobject = static_cast<AnonymousVMObject&>(vmobject);
if (!anonymous_vmobject.is_purgeable() || !anonymous_vmobject.is_volatile())
return IterationDecision::Continue;
if (auto purged_page_count = anonymous_vmobject.purge()) {
dbgln("MM: Purge saved the day! Purged {} pages from AnonymousVMObject", purged_page_count);
page = find_free_user_physical_page(false);
purged_pages = true;
VERIFY(page);
return IterationDecision::Break;
}
return IterationDecision::Continue;
});
if (!page) {
dmesgln("MM: no user physical pages available");
return {};
}
}
if (should_zero_fill == ShouldZeroFill::Yes) {
auto* ptr = quickmap_page(*page);
memset(ptr, 0, PAGE_SIZE);
unquickmap_page();
}
if (did_purge)
*did_purge = purged_pages;
return page;
}
NonnullRefPtrVector<PhysicalPage> MemoryManager::allocate_contiguous_supervisor_physical_pages(size_t size)
{
VERIFY(!(size % PAGE_SIZE));
ScopedSpinLock lock(s_mm_lock);
size_t count = ceil_div(size, static_cast<size_t>(PAGE_SIZE));
auto physical_pages = m_super_physical_region->take_contiguous_free_pages(count);
if (physical_pages.is_empty()) {
dmesgln("MM: no super physical pages available");
VERIFY_NOT_REACHED();
return {};
}
auto cleanup_region = MM.allocate_kernel_region(physical_pages[0].paddr(), PAGE_SIZE * count, "MemoryManager Allocation Sanitization", Region::Access::Read | Region::Access::Write);
fast_u32_fill((u32*)cleanup_region->vaddr().as_ptr(), 0, (PAGE_SIZE * count) / sizeof(u32));
m_system_memory_info.super_physical_pages_used += count;
return physical_pages;
}
RefPtr<PhysicalPage> MemoryManager::allocate_supervisor_physical_page()
{
ScopedSpinLock lock(s_mm_lock);
auto page = m_super_physical_region->take_free_page();
if (!page) {
dmesgln("MM: no super physical pages available");
VERIFY_NOT_REACHED();
return {};
}
fast_u32_fill((u32*)page->paddr().offset(physical_to_virtual_offset).as_ptr(), 0, PAGE_SIZE / sizeof(u32));
++m_system_memory_info.super_physical_pages_used;
return page;
}
void MemoryManager::enter_process_paging_scope(Process& process)
{
enter_space(process.address_space());
}
void MemoryManager::enter_space(AddressSpace& space)
{
auto current_thread = Thread::current();
VERIFY(current_thread != nullptr);
ScopedSpinLock lock(s_mm_lock);
current_thread->regs().cr3 = space.page_directory().cr3();
write_cr3(space.page_directory().cr3());
}
void MemoryManager::flush_tlb_local(VirtualAddress vaddr, size_t page_count)
{
Processor::flush_tlb_local(vaddr, page_count);
}
void MemoryManager::flush_tlb(PageDirectory const* page_directory, VirtualAddress vaddr, size_t page_count)
{
Processor::flush_tlb(page_directory, vaddr, page_count);
}
PageDirectoryEntry* MemoryManager::quickmap_pd(PageDirectory& directory, size_t pdpt_index)
{
VERIFY(s_mm_lock.own_lock());
auto& mm_data = get_data();
auto& pte = boot_pd_kernel_pt1023[(KERNEL_QUICKMAP_PD - KERNEL_PT1024_BASE) / PAGE_SIZE];
auto pd_paddr = directory.m_directory_pages[pdpt_index]->paddr();
if (pte.physical_page_base() != pd_paddr.get()) {
pte.set_physical_page_base(pd_paddr.get());
pte.set_present(true);
pte.set_writable(true);
pte.set_user_allowed(false);
// Because we must continue to hold the MM lock while we use this
// mapping, it is sufficient to only flush on the current CPU. Other
// CPUs trying to use this API must wait on the MM lock anyway
flush_tlb_local(VirtualAddress(KERNEL_QUICKMAP_PD));
} else {
// Even though we don't allow this to be called concurrently, it's
// possible that this PD was mapped on a different CPU and we don't
// broadcast the flush. If so, we still need to flush the TLB.
if (mm_data.m_last_quickmap_pd != pd_paddr)
flush_tlb_local(VirtualAddress(KERNEL_QUICKMAP_PD));
}
mm_data.m_last_quickmap_pd = pd_paddr;
return (PageDirectoryEntry*)KERNEL_QUICKMAP_PD;
}
PageTableEntry* MemoryManager::quickmap_pt(PhysicalAddress pt_paddr)
{
VERIFY(s_mm_lock.own_lock());
auto& mm_data = get_data();
auto& pte = ((PageTableEntry*)boot_pd_kernel_pt1023)[(KERNEL_QUICKMAP_PT - KERNEL_PT1024_BASE) / PAGE_SIZE];
if (pte.physical_page_base() != pt_paddr.get()) {
pte.set_physical_page_base(pt_paddr.get());
pte.set_present(true);
pte.set_writable(true);
pte.set_user_allowed(false);
// Because we must continue to hold the MM lock while we use this
// mapping, it is sufficient to only flush on the current CPU. Other
// CPUs trying to use this API must wait on the MM lock anyway
flush_tlb_local(VirtualAddress(KERNEL_QUICKMAP_PT));
} else {
// Even though we don't allow this to be called concurrently, it's
// possible that this PT was mapped on a different CPU and we don't
// broadcast the flush. If so, we still need to flush the TLB.
if (mm_data.m_last_quickmap_pt != pt_paddr)
flush_tlb_local(VirtualAddress(KERNEL_QUICKMAP_PT));
}
mm_data.m_last_quickmap_pt = pt_paddr;
return (PageTableEntry*)KERNEL_QUICKMAP_PT;
}
u8* MemoryManager::quickmap_page(PhysicalAddress const& physical_address)
{
VERIFY_INTERRUPTS_DISABLED();
auto& mm_data = get_data();
mm_data.m_quickmap_prev_flags = mm_data.m_quickmap_in_use.lock();
ScopedSpinLock lock(s_mm_lock);
VirtualAddress vaddr(KERNEL_QUICKMAP_PER_CPU_BASE + Processor::id() * PAGE_SIZE);
u32 pte_idx = (vaddr.get() - KERNEL_PT1024_BASE) / PAGE_SIZE;
auto& pte = ((PageTableEntry*)boot_pd_kernel_pt1023)[pte_idx];
if (pte.physical_page_base() != physical_address.get()) {
pte.set_physical_page_base(physical_address.get());
pte.set_present(true);
pte.set_writable(true);
pte.set_user_allowed(false);
flush_tlb_local(vaddr);
}
return vaddr.as_ptr();
}
void MemoryManager::unquickmap_page()
{
VERIFY_INTERRUPTS_DISABLED();
ScopedSpinLock lock(s_mm_lock);
auto& mm_data = get_data();
VERIFY(mm_data.m_quickmap_in_use.is_locked());
VirtualAddress vaddr(KERNEL_QUICKMAP_PER_CPU_BASE + Processor::id() * PAGE_SIZE);
u32 pte_idx = (vaddr.get() - KERNEL_PT1024_BASE) / PAGE_SIZE;
auto& pte = ((PageTableEntry*)boot_pd_kernel_pt1023)[pte_idx];
pte.clear();
flush_tlb_local(vaddr);
mm_data.m_quickmap_in_use.unlock(mm_data.m_quickmap_prev_flags);
}
bool MemoryManager::validate_user_stack_no_lock(AddressSpace& space, VirtualAddress vaddr) const
{
VERIFY(space.get_lock().own_lock());
if (!is_user_address(vaddr))
return false;
auto* region = find_user_region_from_vaddr_no_lock(space, vaddr);
return region && region->is_user() && region->is_stack();
}
bool MemoryManager::validate_user_stack(AddressSpace& space, VirtualAddress vaddr) const
{
ScopedSpinLock lock(space.get_lock());
return validate_user_stack_no_lock(space, vaddr);
}
void MemoryManager::register_vmobject(VMObject& vmobject)
{
ScopedSpinLock lock(s_mm_lock);
m_vmobjects.append(vmobject);
}
void MemoryManager::unregister_vmobject(VMObject& vmobject)
{
ScopedSpinLock lock(s_mm_lock);
m_vmobjects.remove(vmobject);
}
void MemoryManager::register_region(Region& region)
{
ScopedSpinLock lock(s_mm_lock);
if (region.is_kernel())
m_kernel_regions.append(region);
}
void MemoryManager::unregister_region(Region& region)
{
ScopedSpinLock lock(s_mm_lock);
if (region.is_kernel())
m_kernel_regions.remove(region);
}
void MemoryManager::dump_kernel_regions()
{
dbgln("Kernel regions:");
#if ARCH(I386)
auto addr_padding = "";
#else
auto addr_padding = " ";
#endif
dbgln("BEGIN{} END{} SIZE{} ACCESS NAME",
addr_padding, addr_padding, addr_padding);
ScopedSpinLock lock(s_mm_lock);
for (auto& region : m_kernel_regions) {
dbgln("{:p} -- {:p} {:p} {:c}{:c}{:c}{:c}{:c}{:c} {}",
region.vaddr().get(),
region.vaddr().offset(region.size() - 1).get(),
region.size(),
region.is_readable() ? 'R' : ' ',
region.is_writable() ? 'W' : ' ',
region.is_executable() ? 'X' : ' ',
region.is_shared() ? 'S' : ' ',
region.is_stack() ? 'T' : ' ',
region.is_syscall_region() ? 'C' : ' ',
region.name());
}
}
void MemoryManager::set_page_writable_direct(VirtualAddress vaddr, bool writable)
{
ScopedSpinLock page_lock(kernel_page_directory().get_lock());
ScopedSpinLock lock(s_mm_lock);
auto* pte = ensure_pte(kernel_page_directory(), vaddr);
VERIFY(pte);
if (pte->is_writable() == writable)
return;
pte->set_writable(writable);
flush_tlb(&kernel_page_directory(), vaddr);
}
CommittedPhysicalPageSet::~CommittedPhysicalPageSet()
{
if (m_page_count)
MM.uncommit_user_physical_pages({}, m_page_count);
}
NonnullRefPtr<PhysicalPage> CommittedPhysicalPageSet::take_one()
{
VERIFY(m_page_count > 0);
--m_page_count;
return MM.allocate_committed_user_physical_page({}, MemoryManager::ShouldZeroFill::Yes);
}
void CommittedPhysicalPageSet::uncommit_one()
{
VERIFY(m_page_count > 0);
--m_page_count;
MM.uncommit_user_physical_pages({}, 1);
}
}
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