More work on per-process page directories. It basically works now!

I spent some time stuck on a problem where processes would clobber each
other's stacks. Took me a moment to figure out that their stacks
were allocated in the sub-4MB linear address range which is shared
between all processes. Oops!
This commit is contained in:
Andreas Kling 2018-11-01 11:30:48 +01:00
parent 1da0a7c949
commit c45f166c63
5 changed files with 147 additions and 61 deletions

View file

@ -6,6 +6,8 @@
#include "StdLib.h"
#include "Task.h"
//#define MM_DEBUG
static MemoryManager* s_the;
MemoryManager& MM
@ -15,10 +17,12 @@ MemoryManager& MM
MemoryManager::MemoryManager()
{
m_pageDirectory = (dword*)0x5000;
m_kernel_page_directory = (dword*)0x5000;
m_pageTableZero = (dword*)0x6000;
m_pageTableOne = (dword*)0x7000;
m_next_laddr.set(0xd0000000);
initializePaging();
}
@ -26,12 +30,12 @@ MemoryManager::~MemoryManager()
{
}
void MemoryManager::populatePageDirectory(Task& task)
void MemoryManager::populate_page_directory(Task& task)
{
memset(task.m_pageDirectory, 0, 4096);
task.m_pageDirectory[0] = m_pageDirectory[0];
task.m_pageDirectory[1] = m_pageDirectory[1];
task.m_pageDirectory[0] = m_kernel_page_directory[0];
task.m_pageDirectory[1] = m_kernel_page_directory[1];
}
void MemoryManager::initializePaging()
@ -40,10 +44,10 @@ void MemoryManager::initializePaging()
static_assert(sizeof(MemoryManager::PageTableEntry) == 4);
memset(m_pageTableZero, 0, 4096);
memset(m_pageTableOne, 0, 4096);
memset(m_pageDirectory, 0, 4096);
memset(m_kernel_page_directory, 0, 4096);
#ifdef MM_DEBUG
kprintf("MM: Page directory @ %p\n", m_pageDirectory);
kprintf("MM: Kernel page directory @ %p\n", m_kernel_page_directory);
#endif
// Make null dereferences crash.
@ -56,7 +60,7 @@ void MemoryManager::initializePaging()
m_freePages.append(PhysicalAddress(i));
}
asm volatile("movl %%eax, %%cr3"::"a"(m_pageDirectory));
asm volatile("movl %%eax, %%cr3"::"a"(m_kernel_page_directory));
asm volatile(
"movl %cr0, %eax\n"
"orl $0x80000001, %eax\n"
@ -69,19 +73,20 @@ void* MemoryManager::allocatePageTable()
auto ppages = allocatePhysicalPages(1);
dword address = ppages[0].get();
identityMap(LinearAddress(address), 4096);
memset((void*)address, 0, 4096);
return (void*)address;
}
auto MemoryManager::ensurePTE(dword* pageDirectory, LinearAddress linearAddress) -> PageTableEntry
auto MemoryManager::ensurePTE(dword* page_directory, LinearAddress laddr) -> PageTableEntry
{
ASSERT_INTERRUPTS_DISABLED();
dword pageDirectoryIndex = (linearAddress.get() >> 22) & 0x3ff;
dword pageTableIndex = (linearAddress.get() >> 12) & 0x3ff;
dword pageDirectoryIndex = (laddr.get() >> 22) & 0x3ff;
dword pageTableIndex = (laddr.get() >> 12) & 0x3ff;
PageDirectoryEntry pde = PageDirectoryEntry(&pageDirectory[pageDirectoryIndex]);
PageDirectoryEntry pde = PageDirectoryEntry(&page_directory[pageDirectoryIndex]);
if (!pde.isPresent()) {
#ifdef MM_DEBUG
kprintf("MM: PDE %u not present, allocating\n", pageDirectoryIndex);
dbgprintf("MM: PDE %u not present, allocating\n", pageDirectoryIndex);
#endif
if (pageDirectoryIndex == 0) {
pde.setPageTableBase((dword)m_pageTableZero);
@ -95,8 +100,9 @@ auto MemoryManager::ensurePTE(dword* pageDirectory, LinearAddress linearAddress)
pde.setWritable(true);
} else {
auto* pageTable = allocatePageTable();
kprintf("MM: Allocated page table #%u (for laddr=%p) at %p\n", pageDirectoryIndex, linearAddress.get(), pageTable);
memset(pageTable, 0, 4096);
#ifdef MM_DEBUG
dbgprintf("MM: PDE %x allocated page table #%u (for laddr=%p) at %p\n", page_directory, pageDirectoryIndex, laddr.get(), pageTable);
#endif
pde.setPageTableBase((dword)pageTable);
pde.setUserAllowed(true);
pde.setPresent(true);
@ -112,7 +118,7 @@ void MemoryManager::protectMap(LinearAddress linearAddress, size_t length)
// FIXME: ASSERT(linearAddress is 4KB aligned);
for (dword offset = 0; offset < length; offset += 4096) {
auto pteAddress = linearAddress.offset(offset);
auto pte = ensurePTE(m_pageDirectory, pteAddress);
auto pte = ensurePTE(m_kernel_page_directory, pteAddress);
pte.setPhysicalPageBase(pteAddress.get());
pte.setUserAllowed(false);
pte.setPresent(false);
@ -127,7 +133,7 @@ void MemoryManager::identityMap(LinearAddress linearAddress, size_t length)
// FIXME: ASSERT(linearAddress is 4KB aligned);
for (dword offset = 0; offset < length; offset += 4096) {
auto pteAddress = linearAddress.offset(offset);
auto pte = ensurePTE(m_pageDirectory, pteAddress);
auto pte = ensurePTE(m_kernel_page_directory, pteAddress);
pte.setPhysicalPageBase(pteAddress.get());
pte.setUserAllowed(true);
pte.setPresent(true);
@ -204,7 +210,7 @@ Vector<PhysicalAddress> MemoryManager::allocatePhysicalPages(size_t count)
byte* MemoryManager::quickMapOnePage(PhysicalAddress physicalAddress)
{
ASSERT_INTERRUPTS_DISABLED();
auto pte = ensurePTE(m_pageDirectory, LinearAddress(4 * MB));
auto pte = ensurePTE(m_kernel_page_directory, LinearAddress(4 * MB));
kprintf("MM: quickmap %x @ %x {pte @ %p}\n", physicalAddress.get(), 4*MB, pte.ptr());
pte.setPhysicalPageBase(physicalAddress.pageBase());
pte.setPresent(true);
@ -213,6 +219,20 @@ byte* MemoryManager::quickMapOnePage(PhysicalAddress physicalAddress)
return (byte*)(4 * MB);
}
void MemoryManager::enter_kernel_paging_scope()
{
InterruptDisabler disabler;
current->m_tss.cr3 = (dword)m_kernel_page_directory;
asm volatile("movl %%eax, %%cr3"::"a"(m_kernel_page_directory));
}
void MemoryManager::enter_task_paging_scope(Task& task)
{
InterruptDisabler disabler;
current->m_tss.cr3 = (dword)task.m_pageDirectory;
asm volatile("movl %%eax, %%cr3"::"a"(task.m_pageDirectory));
}
void MemoryManager::flushEntireTLB()
{
asm volatile(
@ -226,6 +246,67 @@ void MemoryManager::flushTLB(LinearAddress laddr)
asm volatile("invlpg %0": :"m" (*(char*)laddr.get()));
}
void MemoryManager::map_region_at_address(dword* page_directory, Task::Region& region, LinearAddress laddr)
{
InterruptDisabler disabler;
auto& zone = *region.zone;
for (size_t i = 0; i < zone.m_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);
pte.setWritable(true);
pte.setUserAllowed(true);
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());
#endif
}
}
void MemoryManager::unmap_range(dword* page_directory, LinearAddress laddr, size_t size)
{
ASSERT((size % PAGE_SIZE) == 0);
InterruptDisabler disabler;
size_t numPages = size / 4096;
for (size_t i = 0; i < numPages; ++i) {
auto page_laddr = laddr.offset(i * PAGE_SIZE);
auto pte = ensurePTE(page_directory, page_laddr);
pte.setPhysicalPageBase(0);
pte.setPresent(false);
pte.setWritable(false);
pte.setUserAllowed(false);
flushTLB(page_laddr);
#ifdef MM_DEBUG
dbgprintf("MM: << unmap_range L%x =/> 0\n", page_laddr);
#endif
}
}
LinearAddress MemoryManager::allocate_linear_address_range(size_t size)
{
ASSERT((size % PAGE_SIZE) == 0);
// FIXME: Recycle ranges!
auto laddr = m_next_laddr;
m_next_laddr.set(m_next_laddr.get() + size);
return laddr;
}
byte* MemoryManager::create_kernel_alias_for_region(Task::Region& region)
{
InterruptDisabler disabler;
auto laddr = allocate_linear_address_range(region.size);
map_region_at_address(m_kernel_page_directory, region, laddr);
return laddr.asPtr();
}
void MemoryManager::remove_kernel_alias_for_region(Task::Region& region, byte* addr)
{
unmap_range(m_kernel_page_directory, LinearAddress((dword)addr), region.size);
}
bool MemoryManager::unmapRegion(Task& task, Task::Region& region)
{
InterruptDisabler disabler;
@ -238,7 +319,9 @@ bool MemoryManager::unmapRegion(Task& task, Task::Region& region)
pte.setWritable(false);
pte.setUserAllowed(false);
flushTLB(laddr);
//kprintf("MM: >> Unmapped L%x => P%x <<\n", laddr, zone.m_pages[i].get());
#ifdef MM_DEBUG
//dbgprintf("MM: >> Unmapped L%x => P%x <<\n", laddr, zone.m_pages[i].get());
#endif
}
return true;
}
@ -246,7 +329,6 @@ bool MemoryManager::unmapRegion(Task& task, Task::Region& region)
bool MemoryManager::unmapSubregion(Task& task, Task::Subregion& subregion)
{
InterruptDisabler disabler;
auto& region = *subregion.region;
size_t numPages = subregion.size / 4096;
ASSERT(numPages);
for (size_t i = 0; i < numPages; ++i) {
@ -257,7 +339,9 @@ bool MemoryManager::unmapSubregion(Task& task, Task::Subregion& subregion)
pte.setWritable(false);
pte.setUserAllowed(false);
flushTLB(laddr);
//kprintf("MM: >> Unmapped subregion %s L%x => P%x <<\n", subregion.name.characters(), laddr, zone.m_pages[i].get());
#ifdef MM_DEBUG
//dbgprintf("MM: >> Unmapped subregion %s L%x => P%x <<\n", subregion.name.characters(), laddr, zone.m_pages[i].get());
#endif
}
return true;
}
@ -290,27 +374,18 @@ bool MemoryManager::mapSubregion(Task& task, Task::Subregion& subregion)
pte.setPhysicalPageBase(zone.m_pages[firstPage + i].get());
pte.setPresent(true);
pte.setWritable(true);
pte.setUserAllowed(!task.isRing0());
pte.setUserAllowed(true);
flushTLB(laddr);
//kprintf("MM: >> Mapped subregion %s L%x => P%x (%u into region)<<\n", subregion.name.characters(), laddr, zone.m_pages[firstPage + i].get(), subregion.offset);
#ifdef MM_DEBUG
//dbgprintf("MM: >> Mapped subregion %s L%x => P%x (%u into region)\n", subregion.name.characters(), laddr, zone.m_pages[firstPage + i].get(), subregion.offset);
#endif
}
return true;
}
bool MemoryManager::mapRegion(Task& task, Task::Region& region)
{
InterruptDisabler disabler;
auto& zone = *region.zone;
for (size_t i = 0; i < zone.m_pages.size(); ++i) {
auto laddr = region.linearAddress.offset(i * PAGE_SIZE);
auto pte = ensurePTE(task.m_pageDirectory,laddr);
pte.setPhysicalPageBase(zone.m_pages[i].get());
pte.setPresent(true);
pte.setWritable(true);
pte.setUserAllowed(!task.isRing0()); // FIXME: This doesn't make sense. Allow USER if the TASK is RING0? Wh...what?
flushTLB(laddr);
//kprintf("MM: >> Mapped L%x => P%x <<\n", laddr, zone.m_pages[i].get());
}
map_region_at_address(task.m_pageDirectory, region, region.linearAddress);
return true;
}

View file

@ -41,7 +41,7 @@ class MemoryManager {
public:
static MemoryManager& the() PURE;
PhysicalAddress pageDirectoryBase() const { return PhysicalAddress(reinterpret_cast<dword>(m_pageDirectory)); }
PhysicalAddress pageDirectoryBase() const { return PhysicalAddress(reinterpret_cast<dword>(m_kernel_page_directory)); }
static void initialize();
@ -65,12 +65,22 @@ public:
void registerZone(Zone&);
void unregisterZone(Zone&);
void populatePageDirectory(Task&);
void populate_page_directory(Task&);
byte* create_kernel_alias_for_region(Task::Region&);
void remove_kernel_alias_for_region(Task::Region&, byte*);
void enter_kernel_paging_scope();
void enter_task_paging_scope(Task&);
private:
MemoryManager();
~MemoryManager();
LinearAddress allocate_linear_address_range(size_t);
void map_region_at_address(dword* page_directory, Task::Region&, LinearAddress);
void unmap_range(dword* page_directory, LinearAddress, size_t);
void initializePaging();
void flushEntireTLB();
void flushTLB(LinearAddress);
@ -162,10 +172,12 @@ private:
PageTableEntry ensurePTE(dword* pageDirectory, LinearAddress);
dword* m_pageDirectory;
dword* m_kernel_page_directory;
dword* m_pageTableZero;
dword* m_pageTableOne;
LinearAddress m_next_laddr;
HashTable<Zone*> m_zones;
Vector<PhysicalAddress> m_freePages;

View file

@ -61,6 +61,7 @@ ByteBuffer procfs$pid_vm(const Task& task)
ByteBuffer procfs$pid_stack(Task& task)
{
InterruptDisabler disabler;
ASSERT(false);
if (current != &task) {
MM.unmapRegionsForTask(*current);
MM.mapRegionsForTask(task);

View file

@ -228,6 +228,11 @@ int Task::sys$spawn(const char* path, const char** args)
return error;
}
struct KernelPagingScope {
KernelPagingScope() { MM.enter_kernel_paging_scope(); }
~KernelPagingScope() { MM.enter_task_paging_scope(*current); }
};
Task* Task::createUserTask(const String& path, uid_t uid, gid_t gid, pid_t parentPID, int& error, const char** args, TTY* tty)
{
auto parts = path.split('/');
@ -276,6 +281,7 @@ Task* Task::createUserTask(const String& path, uid_t uid, gid_t gid, pid_t paren
taskEnvironment.append("HOME=/");
InterruptDisabler disabler; // FIXME: Get rid of this, jesus christ. This "critical" section is HUGE.
KernelPagingScope kernelScope;
Task* t = new Task(parts.takeLast(), uid, gid, parentPID, Ring3, move(cwd), handle->vnode(), tty);
t->m_arguments = move(taskArguments);
@ -283,20 +289,21 @@ Task* Task::createUserTask(const String& path, uid_t uid, gid_t gid, pid_t paren
ExecSpace space;
Region* region = nullptr;
byte* region_alias = nullptr;
space.hookableAlloc = [&] (const String& name, size_t size) {
if (!size)
return (void*)nullptr;
size = ((size / 4096) + 1) * 4096;
size = ((size / 4096) + 1) * 4096; // FIXME: Use ceil_div?
region = t->allocateRegion(size, String(name));
ASSERT(region);
MM.mapRegion(*t, *region);
return (void*)region->linearAddress.asPtr();
region_alias = MM.create_kernel_alias_for_region(*region);
return (void*)region_alias;
};
bool success = space.loadELF(move(elfData));
if (!success) {
// FIXME: This is ugly. If we need to do this, it should be at a different level.
MM.unmapRegionsForTask(*t);
MM.mapRegionsForTask(*current);
MM.remove_kernel_alias_for_region(*region, region_alias);
delete t;
kprintf("Failure loading ELF %s\n", path.characters());
error = -ENOEXEC;
@ -321,16 +328,15 @@ Task* Task::createUserTask(const String& path, uid_t uid, gid_t gid, pid_t paren
t->m_tss.eip = (dword)space.symbolPtr("_start");
if (!t->m_tss.eip) {
// FIXME: This is ugly. If we need to do this, it should be at a different level.
MM.unmapRegionsForTask(*t);
MM.mapRegionsForTask(*current);
MM.remove_kernel_alias_for_region(*region, region_alias);
delete t;
error = -ENOEXEC;
return nullptr;
}
// FIXME: This is ugly. If we need to do this, it should be at a different level.
MM.unmapRegionsForTask(*t);
MM.mapRegionsForTask(*current);
MM.remove_kernel_alias_for_region(*region, region_alias);
MM.mapRegionsForTask(*t);
s_tasks->prepend(t);
system.nprocess++;
@ -409,7 +415,7 @@ Task::Task(String&& name, uid_t uid, gid_t gid, pid_t parentPID, RingLevel ring,
, m_parentPID(parentPID)
{
m_pageDirectory = (dword*)kmalloc_page_aligned(4096);
MM.populatePageDirectory(*this);
MM.populate_page_directory(*this);
if (tty) {
m_fileHandles.append(tty->open(O_RDONLY)); // stdin
@ -421,7 +427,7 @@ Task::Task(String&& name, uid_t uid, gid_t gid, pid_t parentPID, RingLevel ring,
m_fileHandles.append(nullptr); // stderr
}
m_nextRegion = LinearAddress(0x600000);
m_nextRegion = LinearAddress(0x10000000);
memset(&m_tss, 0, sizeof(m_tss));
@ -539,8 +545,6 @@ void Task::sys$exit(int status)
setState(Exiting);
MM.unmapRegionsForTask(*this);
s_tasks->remove(this);
notify_waiters(m_pid, status, 0);
@ -566,7 +570,6 @@ void Task::murder(int signal)
if (wasCurrent) {
kprintf("Current task committing suicide!\n");
MM.unmapRegionsForTask(*this);
if (!scheduleNewTask()) {
kprintf("Task::murder: Failed to schedule a new task :(\n");
HANG;
@ -593,8 +596,6 @@ void Task::taskDidCrash(Task* crashedTask)
notify_waiters(crashedTask->m_pid, 0, SIGSEGV);
MM.unmapRegionsForTask(*crashedTask);
if (!scheduleNewTask()) {
kprintf("Task::taskDidCrash: Failed to schedule a new task :(\n");
HANG;
@ -750,14 +751,8 @@ static bool contextSwitch(Task* t)
// mark it as runnable for the next round.
if (current->state() == Task::Running)
current->setState(Task::Runnable);
bool success = MM.unmapRegionsForTask(*current);
ASSERT(success);
}
bool success = MM.mapRegionsForTask(*t);
ASSERT(success);
current = t;
t->setState(Task::Running);

View file

@ -29,6 +29,7 @@
#define TEST_VFS
#define KSYMS
#define SPAWN_MULTIPLE_SHELLS
//#define STRESS_TEST_SPAWNING
//#define TEST_ELF_LOADER
@ -188,9 +189,11 @@ static void init_stage2()
int error;
auto* sh0 = Task::createUserTask("/bin/sh", (uid_t)100, (gid_t)100, (pid_t)0, error, nullptr, tty0);
#ifdef SPAWN_MULTIPLE_SHELLS
auto* sh1 = Task::createUserTask("/bin/sh", (uid_t)100, (gid_t)100, (pid_t)0, error, nullptr, tty1);
auto* sh2 = Task::createUserTask("/bin/sh", (uid_t)100, (gid_t)100, (pid_t)0, error, nullptr, tty2);
auto* sh3 = Task::createUserTask("/bin/sh", (uid_t)100, (gid_t)100, (pid_t)0, error, nullptr, tty3);
#endif
#if 0
// It would be nice to exit this process, but right now it instantiates all kinds of things.