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Replace zones with individually tracked physical pages.

Browse source 
It's just a simple struct { ref_count, paddr }.
This will allow me to implement lazy zeroing and COW pages.
This commit is contained in:
Andreas Kling 2018-11-05 10:23:00 +01:00
parent b5c5286ee1
commit 72cdc62155
10 changed files with 161 additions and 127 deletions
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3
AK/RetainPtr.h
View file

@ -32,6 +32,7 @@ public:
RetainPtr(RetainPtr& other) : m_ptr(other.copyRef().leakRef()) { }
RetainPtr(RetainPtr&& other) : m_ptr(other.leakRef()) { }
template<typename U> RetainPtr(RetainPtr<U>&& other) : m_ptr(static_cast<T*>(other.leakRef())) { }
RetainPtr(const RetainPtr& other) : m_ptr(const_cast<RetainPtr&>(other).copyRef().leakRef()) { }
~RetainPtr()
{
clear();
@ -121,6 +122,8 @@ public:
operator bool() { return !!m_ptr; }
bool is_null() const { return !m_ptr; }
private:
T* m_ptr = nullptr;
};

17
AK/Vector.h
View file

@ -75,6 +75,13 @@ public:
other.m_impl = nullptr;
}
Vector(const Vector& other)
{
ensureCapacity(other.size());
for (size_t i = 0; i < other.size(); ++i)
unchecked_append(other[i]);
}
Vector& operator=(Vector&& other)
{
if (this != &other) {
@ -140,16 +147,22 @@ public:
Vector<T> tmp = move(other);
ensureCapacity(size() + tmp.size());
for (auto&& v : tmp) {
uncheckedAppend(move(v));
unchecked_append(move(v));
}
}
void uncheckedAppend(T&& value)
void unchecked_append(T&& value)
{
new (m_impl->slot(m_impl->m_size)) T(move(value));
++m_impl->m_size;
}
void unchecked_append(const T& value)
{
new (m_impl->slot(m_impl->m_size)) T(value);
++m_impl->m_size;
}
void append(T&& value)
{
ensureCapacity(size() + 1);

149
Kernel/MemoryManager.cpp
View file

@ -45,12 +45,12 @@ void MemoryManager::release_page_directory(PageDirectory& page_directory)
dbgprintf("MM: release_page_directory for PD K%x\n", &page_directory);
#endif
for (size_t i = 0; i < 1024; ++i) {
auto page_table = page_directory.physical_addresses[i];
auto& page_table = page_directory.physical_pages[i];
if (!page_table.is_null()) {
#ifdef MM_DEBUG
dbgprintf("MM: deallocating process page table [%u] P%x @ %p\n", i, page_table.get(), &process.m_page_directory->physical_addresses[i]);
dbgprintf("MM: deallocating user page table P%x\n", page_table->paddr().get());
#endif
deallocate_page_table(page_table);
deallocate_page_table(page_directory, i);
}
}
#ifdef SCRUB_DEALLOCATED_PAGE_TABLES
@ -76,9 +76,9 @@ void MemoryManager::initializePaging()
// The bottom 4 MB are identity mapped & supervisor only. Every process shares these mappings.
create_identity_mapping(LinearAddress(PAGE_SIZE), 4 * MB);
// The physical pages 4 MB through 8 MB are available for Zone allocation.
// The physical pages 4 MB through 8 MB are available for allocation.
for (size_t i = (4 * MB) + PAGE_SIZE; i < (8 * MB); i += PAGE_SIZE)
m_freePages.append(PhysicalAddress(i));
m_free_physical_pages.append(adopt(*new PhysicalPage(PhysicalAddress(i))));
asm volatile("movl %%eax, %%cr3"::"a"(m_kernel_page_directory));
asm volatile(
@ -88,20 +88,29 @@ void MemoryManager::initializePaging()
);
}
PhysicalAddress MemoryManager::allocate_page_table()
RetainPtr<PhysicalPage> MemoryManager::allocate_page_table(PageDirectory& page_directory, unsigned index)
{
auto ppages = allocatePhysicalPages(1);
dword address = ppages[0].get();
auto& page_directory_physical_ptr = page_directory.physical_pages[index];
ASSERT(!page_directory_physical_ptr);
auto ppages = allocate_physical_pages(1);
ASSERT(ppages.size() == 1);
dword address = ppages[0]->paddr().get();
create_identity_mapping(LinearAddress(address), PAGE_SIZE);
memset((void*)address, 0, PAGE_SIZE);
return PhysicalAddress(address);
page_directory.physical_pages[index] = move(ppages[0]);
return page_directory.physical_pages[index];
}
void MemoryManager::deallocate_page_table(PhysicalAddress paddr)
void MemoryManager::deallocate_page_table(PageDirectory& page_directory, unsigned index)
{
ASSERT(!m_freePages.contains_slow(paddr));
remove_identity_mapping(LinearAddress(paddr.get()), PAGE_SIZE);
m_freePages.append(paddr);
auto& physical_page = page_directory.physical_pages[index];
ASSERT(physical_page);
ASSERT(!m_free_physical_pages.contains_slow(physical_page));
for (size_t i = 0; i < MM.m_free_physical_pages.size(); ++i) {
ASSERT(MM.m_free_physical_pages[i].ptr() != physical_page.ptr());
}
remove_identity_mapping(LinearAddress(physical_page->paddr().get()), PAGE_SIZE);
page_directory.physical_pages[index] = nullptr;
}
void MemoryManager::remove_identity_mapping(LinearAddress laddr, size_t size)
@ -143,20 +152,21 @@ auto MemoryManager::ensurePTE(PageDirectory* page_directory, LinearAddress laddr
pde.setPresent(true);
pde.setWritable(true);
} else {
auto page_table = allocate_page_table();
auto page_table = allocate_page_table(*page_directory, page_directory_index);
#ifdef MM_DEBUG
dbgprintf("MM: PD K%x (%s) allocated page table #%u (for L%x) at P%x\n",
page_directory,
page_directory == m_kernel_page_directory ? "Kernel" : "User",
page_directory_index,
laddr.get(),
page_table);
page_table->paddr().get());
#endif
page_directory->physical_addresses[page_directory_index] = page_table;
pde.setPageTableBase(page_table.get());
pde.setPageTableBase(page_table->paddr().get());
pde.setUserAllowed(true);
pde.setPresent(true);
pde.setWritable(true);
page_directory->physical_pages[page_directory_index] = move(page_table);
}
}
return PageTableEntry(&pde.pageTableBase()[page_table_index]);
@ -209,61 +219,18 @@ PageFaultResponse MemoryManager::handlePageFault(const PageFault& fault)
return PageFaultResponse::ShouldCrash;
}
void MemoryManager::registerZone(Zone& zone)
{
ASSERT_INTERRUPTS_DISABLED();
m_zones.set(&zone);
#ifdef MM_DEBUG
for (size_t i = 0; i < zone.m_pages.size(); ++i)
dbgprintf("MM: allocated to zone: P%x\n", zone.m_pages[i].get());
#endif
}
void MemoryManager::unregisterZone(Zone& zone)
{
ASSERT_INTERRUPTS_DISABLED();
#ifdef MM_DEBUG
for (size_t i = 0; i < zone.m_pages.size(); ++i)
dbgprintf("MM: deallocated from zone: P%x\n", zone.m_pages[i].get());
#endif
m_zones.remove(&zone);
m_freePages.append(move(zone.m_pages));
}
Zone::Zone(Vector<PhysicalAddress>&& pages)
: m_pages(move(pages))
{
MM.registerZone(*this);
}
Zone::~Zone()
{
MM.unregisterZone(*this);
}
RetainPtr<Zone> MemoryManager::createZone(size_t size)
Vector<RetainPtr<PhysicalPage>> MemoryManager::allocate_physical_pages(size_t count)
{
InterruptDisabler disabler;
auto pages = allocatePhysicalPages(ceilDiv(size, PAGE_SIZE));
if (pages.isEmpty()) {
kprintf("MM: createZone: no physical pages for size %u\n", size);
return nullptr;
}
return adopt(*new Zone(move(pages)));
}
Vector<PhysicalAddress> MemoryManager::allocatePhysicalPages(size_t count)
{
InterruptDisabler disabler;
if (count > m_freePages.size())
if (count > m_free_physical_pages.size())
return { };
Vector<PhysicalAddress> pages;
Vector<RetainPtr<PhysicalPage>> pages;
pages.ensureCapacity(count);
for (size_t i = 0; i < count; ++i) {
pages.append(m_freePages.takeLast());
pages.append(m_free_physical_pages.takeLast());
#ifdef MM_DEBUG
dbgprintf("MM: allocate_physical_pages vending P%x\n", pages.last());
dbgprintf("MM: allocate_physical_pages vending P%x\n", pages.last()->paddr().get());
#endif
}
return pages;
@ -299,17 +266,22 @@ void MemoryManager::flushTLB(LinearAddress laddr)
void MemoryManager::map_region_at_address(PageDirectory* page_directory, Region& region, LinearAddress laddr, bool user_allowed)
{
InterruptDisabler disabler;
auto& zone = *region.zone;
for (size_t i = 0; i < zone.m_pages.size(); ++i) {
for (size_t i = 0; i < region.physical_pages.size(); ++i) {
auto page_laddr = laddr.offset(i * PAGE_SIZE);
auto pte = ensurePTE(page_directory, page_laddr);
pte.setPhysicalPageBase(zone.m_pages[i].get());
pte.setPresent(true); // FIXME: Maybe we could use the is_readable flag here?
auto& physical_page = region.physical_pages[i];
if (physical_page) {
pte.setPhysicalPageBase(physical_page->paddr().get());
pte.setPresent(true); // FIXME: Maybe we should use the is_readable flag here?
} else {
pte.setPhysicalPageBase(0);
pte.setPresent(false);
}
pte.setWritable(region.is_writable);
pte.setUserAllowed(user_allowed);
flushTLB(page_laddr);
#ifdef MM_DEBUG
dbgprintf("MM: >> map_region_at_address (PD=%x) L%x => P%x\n", page_directory, page_laddr, zone.m_pages[i].get());
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
}
}
@ -369,8 +341,7 @@ void MemoryManager::remove_kernel_alias_for_region(Region& region, byte* addr)
bool MemoryManager::unmapRegion(Process& process, Region& region)
{
InterruptDisabler disabler;
auto& zone = *region.zone;
for (size_t i = 0; i < zone.m_pages.size(); ++i) {
for (size_t i = 0; i < region.physical_pages.size(); ++i) {
auto laddr = region.linearAddress.offset(i * PAGE_SIZE);
auto pte = ensurePTE(process.m_page_directory, laddr);
pte.setPhysicalPageBase(0);
@ -379,7 +350,8 @@ bool MemoryManager::unmapRegion(Process& process, Region& region)
pte.setUserAllowed(false);
flushTLB(laddr);
#ifdef MM_DEBUG
//dbgprintf("MM: >> Unmapped L%x => P%x <<\n", laddr, zone.m_pages[i].get());
auto& physical_page = region.physical_pages[i];
dbgprintf("MM: >> Unmapped L%x => P%x <<\n", laddr, physical_page ? physical_page->paddr().get() : 0);
#endif
}
return true;
@ -429,12 +401,12 @@ RetainPtr<Region> Region::clone()
KernelPagingScope pagingScope;
if (is_readable && !is_writable) {
// Create a new region backed by the same zone.
return adopt(*new Region(linearAddress, size, zone.copyRef(), String(name), is_readable, is_writable));
// Create a new region backed by the same physical pages.
return adopt(*new Region(linearAddress, size, physical_pages, String(name), is_readable, is_writable));
}
// FIXME: Implement COW regions.
auto clone_zone = MM.createZone(zone->size());
auto clone_region = adopt(*new Region(linearAddress, size, move(clone_zone), String(name), is_readable, is_writable));
auto clone_physical_pages = MM.allocate_physical_pages(physical_pages.size());
auto clone_region = adopt(*new Region(linearAddress, size, move(clone_physical_pages), String(name), is_readable, is_writable));
// FIXME: It would be cool to make the src_alias a read-only mapping.
byte* src_alias = MM.create_kernel_alias_for_region(*this);
@ -447,3 +419,26 @@ RetainPtr<Region> Region::clone()
return clone_region;
}
Region::Region(LinearAddress a, size_t s, Vector<RetainPtr<PhysicalPage>> pp, String&& n, bool r, bool w)
: linearAddress(a)
, size(s)
, physical_pages(move(pp))
, name(move(n))
, is_readable(r)
, is_writable(w)
{
}
Region::~Region()
{
}
void PhysicalPage::return_to_freelist()
{
InterruptDisabler disabler;
m_retain_count = 1;
MM.m_free_physical_pages.append(adopt(*this));
#ifdef MM_DEBUG
dbgprintf("MM: P%x released to freelist\n", m_paddr.get());
#endif
}

64
Kernel/MemoryManager.h
View file

@ -17,34 +17,50 @@ enum class PageFaultResponse {
Continue,
};
struct PageDirectory {
dword entries[1024];
PhysicalAddress physical_addresses[1024];
};
struct Zone : public Retainable<Zone> {
friend ByteBuffer procfs$mm();
class PhysicalPage {
friend class MemoryManager;
public:
~Zone();
size_t size() const { return m_pages.size() * PAGE_SIZE; }
~PhysicalPage() { }
PhysicalAddress paddr() const { return m_paddr; }
const Vector<PhysicalAddress>& pages() const { return m_pages; }
void retain()
{
ASSERT(m_retain_count);
++m_retain_count;
}
void release()
{
ASSERT(m_retain_count);
if (!--m_retain_count)
return_to_freelist();
}
private:
friend class MemoryManager;
explicit Zone(Vector<PhysicalAddress>&&);
PhysicalPage(PhysicalAddress paddr)
: m_paddr(paddr)
{
}
Vector<PhysicalAddress> m_pages;
void return_to_freelist();
unsigned m_retain_count { 1 };
PhysicalAddress m_paddr;
};
struct PageDirectory {
dword entries[1024];
RetainPtr<PhysicalPage> physical_pages[1024];
};
struct Region : public Retainable<Region> {
Region(LinearAddress, size_t, RetainPtr<Zone>&&, String&&, bool r, bool w);
Region(LinearAddress, size_t, Vector<RetainPtr<PhysicalPage>>, String&&, bool r, bool w);
~Region();
RetainPtr<Region> clone();
LinearAddress linearAddress;
size_t size { 0 };
RetainPtr<Zone> zone;
Vector<RetainPtr<PhysicalPage>> physical_pages;
String name;
bool is_readable { true };
bool is_writable { true };
@ -54,6 +70,7 @@ struct Region : public Retainable<Region> {
class MemoryManager {
AK_MAKE_ETERNAL
friend class PhysicalPage;
friend ByteBuffer procfs$mm();
public:
static MemoryManager& the() PURE;
@ -64,14 +81,9 @@ public:
PageFaultResponse handlePageFault(const PageFault&);
RetainPtr<Zone> createZone(size_t);
bool mapRegion(Process&, Region&);
bool unmapRegion(Process&, Region&);
void registerZone(Zone&);
void unregisterZone(Zone&);
void populate_page_directory(PageDirectory&);
void release_page_directory(PageDirectory&);
@ -84,6 +96,8 @@ public:
bool validate_user_read(const Process&, LinearAddress) const;
bool validate_user_write(const Process&, LinearAddress) const;
Vector<RetainPtr<PhysicalPage>> allocate_physical_pages(size_t count);
private:
MemoryManager();
~MemoryManager();
@ -96,16 +110,14 @@ private:
void flushEntireTLB();
void flushTLB(LinearAddress);
PhysicalAddress allocate_page_table();
void deallocate_page_table(PhysicalAddress);
RetainPtr<PhysicalPage> allocate_page_table(PageDirectory&, unsigned index);
void deallocate_page_table(PageDirectory&, unsigned index);
void protectMap(LinearAddress, size_t length);
void create_identity_mapping(LinearAddress, size_t length);
void remove_identity_mapping(LinearAddress, size_t);
Vector<PhysicalAddress> allocatePhysicalPages(size_t count);
struct PageDirectoryEntry {
explicit PageDirectoryEntry(dword* pde) : m_pde(pde) { }
@ -192,9 +204,7 @@ private:
LinearAddress m_next_laddr;
HashTable<Zone*> m_zones;
Vector<PhysicalAddress> m_freePages;
Vector<RetainPtr<PhysicalPage>> m_free_physical_pages;
};
struct KernelPagingScope {

12
Kernel/ProcFileSystem.cpp
View file

@ -49,7 +49,7 @@ ByteBuffer procfs$pid_vm(Process& process)
{
ProcessInspectionScope scope(process);
char* buffer;
auto stringImpl = StringImpl::createUninitialized(80 + process.regionCount() * 80, buffer);
auto stringImpl = StringImpl::createUninitialized(80 + process.regionCount() * 80 + 4096, buffer);
memset(buffer, 0, stringImpl->length());
char* ptr = buffer;
ptr += ksprintf(ptr, "BEGIN END SIZE NAME\n");
@ -59,6 +59,10 @@ ByteBuffer procfs$pid_vm(Process& process)
region->linearAddress.offset(region->size - 1).get(),
region->size,
region->name.characters());
for (auto& physical_page : region->physical_pages) {
ptr += ksprintf(ptr, "P%x ", physical_page ? physical_page->paddr().get() : 0);
}
ptr += ksprintf(ptr, "\n");
}
*ptr = '\0';
return ByteBuffer::copy((byte*)buffer, ptr - buffer);
@ -130,6 +134,8 @@ void ProcFileSystem::removeProcess(Process& process)
ByteBuffer procfs$mm()
{
// FIXME: Implement
#if 0
InterruptDisabler disabler;
size_t zonePageCount = 0;
for (auto* zone : MM.m_zones)
@ -143,9 +149,11 @@ ByteBuffer procfs$mm()
ptr += ksprintf(ptr, "\n");
}
ptr += ksprintf(ptr, "Zone count: %u\n", MM.m_zones.size());
ptr += ksprintf(ptr, "Free physical pages: %u\n", MM.m_freePages.size());
ptr += ksprintf(ptr, "Free physical pages: %u\n", MM.m_free_physical_pages.size());
buffer.trim(ptr - (char*)buffer.pointer());
return buffer;
#endif
return { };
}

23
Kernel/Process.cpp
View file

@ -17,6 +17,7 @@
//#define DEBUG_IO
//#define TASK_DEBUG
//#define FORK_DEBUG
//#define SCHEDULER_DEBUG
// FIXME: Only do a single validation for accesses that don't span multiple pages.
@ -144,11 +145,11 @@ Region* Process::allocate_region(LinearAddress laddr, size_t size, String&& name
laddr.mask(0xfffff000);
auto zone = MM.createZone(size);
ASSERT(zone);
m_regions.append(adopt(*new Region(laddr, size, move(zone), move(name), is_readable, is_writable)));
unsigned page_count = ceilDiv(size, PAGE_SIZE);
auto physical_pages = MM.allocate_physical_pages(page_count);
ASSERT(physical_pages.size() == page_count);
m_regions.append(adopt(*new Region(laddr, size, move(physical_pages), move(name), is_readable, is_writable)));
MM.mapRegion(*this, *m_regions.last());
return m_regions.last().ptr();
}
@ -1258,20 +1259,6 @@ Process* Process::kernelProcess()
return s_kernelProcess;
}
Region::Region(LinearAddress a, size_t s, RetainPtr<Zone>&& z, String&& n, bool r, bool w)
: linearAddress(a)
, size(s)
, zone(move(z))
, name(move(n))
, is_readable(r)
, is_writable(w)
{
}
Region::~Region()
{
}
bool Process::isValidAddressForKernel(LinearAddress laddr) const
{
// We check extra carefully here since the first 4MB of the address space is identity-mapped.

2
Kernel/i386.cpp
View file

@ -318,7 +318,7 @@ void gdt_init()
s_gdt_freelist = new Vector<word, KmallocEternalAllocator>();
s_gdt_freelist->ensureCapacity(256);
for (size_t i = s_gdtLength; i < 256; ++i)
s_gdt_freelist->uncheckedAppend(i * 8);
s_gdt_freelist->unchecked_append(i * 8);
s_gdtLength = 256;
s_gdtr.address = s_gdt;

1
Kernel/sync.sh
View file

@ -19,6 +19,7 @@ cp ../Userland/uname mnt/bin/uname
cp ../Userland/clear mnt/bin/clear
cp ../Userland/tst mnt/bin/tst
cp ../Userland/ft mnt/bin/ft
cp ../Userland/ft2 mnt/bin/ft2
cp ../Userland/mm mnt/bin/mm
cp ../Userland/kill mnt/bin/kill
cp ../Userland/tty mnt/bin/tty

1
Userland/.gitignore vendored
View file

@ -17,3 +17,4 @@ mm
kill
tty
ft
ft2

16
Userland/ft2.cpp Normal file
View file

@ -0,0 +1,16 @@
#include <stdio.h>
#include <unistd.h>
int main(int argc, char** argv)
{
printf("Testing fork()...\n");
pid_t pid = fork();
if (!pid) {
printf("child, pid=%d\n", getpid());
for (;;);
} else {
printf("parent, child pid=%d\n", pid);
for (;;);
}
return 0;
}