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Kernel: Factor address space management out of the Process class

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This patch adds Space, a class representing a process's address space.

- Each Process has a Space.
- The Space owns the PageDirectory and all Regions in the Process.

This allows us to reorganize sys$execve() so that it constructs and
populates a new Space fully before committing to it.

Previously, we would construct the new address space while still
running in the old one, and encountering an error meant we had to do
tedious and error-prone rollback.

Those problems are now gone, replaced by what's hopefully a set of much
smaller problems and missing cleanups. :^)
This commit is contained in:
Andreas Kling 2021-02-08 15:45:40 +01:00
parent b2cba3036e
commit f1b5def8fd
27 changed files with 494 additions and 404 deletions
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171
Kernel/Process.cpp
View file

@ -116,110 +116,6 @@ bool Process::in_group(gid_t gid) const
return m_gid == gid || m_extra_gids.contains_slow(gid);
}
Optional<Range> Process::allocate_range(VirtualAddress vaddr, size_t size, size_t alignment)
{
vaddr.mask(PAGE_MASK);
size = PAGE_ROUND_UP(size);
if (vaddr.is_null())
return page_directory().range_allocator().allocate_anywhere(size, alignment);
return page_directory().range_allocator().allocate_specific(vaddr, size);
}
Region& Process::allocate_split_region(const Region& source_region, const Range& range, size_t offset_in_vmobject)
{
auto& region = add_region(
Region::create_user_accessible(this, range, source_region.vmobject(), offset_in_vmobject, source_region.name(), source_region.access(), source_region.is_cacheable(), source_region.is_shared()));
region.set_syscall_region(source_region.is_syscall_region());
region.set_mmap(source_region.is_mmap());
region.set_stack(source_region.is_stack());
size_t page_offset_in_source_region = (offset_in_vmobject - source_region.offset_in_vmobject()) / PAGE_SIZE;
for (size_t i = 0; i < region.page_count(); ++i) {
if (source_region.should_cow(page_offset_in_source_region + i))
region.set_should_cow(i, true);
}
return region;
}
KResultOr<Region*> Process::allocate_region(const Range& range, const String& name, int prot, AllocationStrategy strategy)
{
ASSERT(range.is_valid());
auto vmobject = AnonymousVMObject::create_with_size(range.size(), strategy);
if (!vmobject)
return ENOMEM;
auto region = Region::create_user_accessible(this, range, vmobject.release_nonnull(), 0, name, prot_to_region_access_flags(prot), true, false);
if (!region->map(page_directory()))
return ENOMEM;
return &add_region(move(region));
}
KResultOr<Region*> Process::allocate_region_with_vmobject(const Range& range, NonnullRefPtr<VMObject> vmobject, size_t offset_in_vmobject, const String& name, int prot, bool shared)
{
ASSERT(range.is_valid());
size_t end_in_vmobject = offset_in_vmobject + range.size();
if (end_in_vmobject <= offset_in_vmobject) {
dbgln("allocate_region_with_vmobject: Overflow (offset + size)");
return EINVAL;
}
if (offset_in_vmobject >= vmobject->size()) {
dbgln("allocate_region_with_vmobject: Attempt to allocate a region with an offset past the end of its VMObject.");
return EINVAL;
}
if (end_in_vmobject > vmobject->size()) {
dbgln("allocate_region_with_vmobject: Attempt to allocate a region with an end past the end of its VMObject.");
return EINVAL;
}
offset_in_vmobject &= PAGE_MASK;
auto& region = add_region(Region::create_user_accessible(this, range, move(vmobject), offset_in_vmobject, name, prot_to_region_access_flags(prot), true, shared));
if (!region.map(page_directory())) {
// FIXME: What is an appropriate error code here, really?
return ENOMEM;
}
return &region;
}
bool Process::deallocate_region(Region& region)
{
OwnPtr<Region> region_protector;
ScopedSpinLock lock(m_lock);
if (m_region_lookup_cache.region.unsafe_ptr() == &region)
m_region_lookup_cache.region = nullptr;
for (size_t i = 0; i < m_regions.size(); ++i) {
if (&m_regions[i] == &region) {
region_protector = m_regions.unstable_take(i);
return true;
}
}
return false;
}
Region* Process::find_region_from_range(const Range& range)
{
ScopedSpinLock lock(m_lock);
if (m_region_lookup_cache.range.has_value() && m_region_lookup_cache.range.value() == range && m_region_lookup_cache.region)
return m_region_lookup_cache.region.unsafe_ptr();
size_t size = PAGE_ROUND_UP(range.size());
for (auto& region : m_regions) {
if (region.vaddr() == range.base() && region.size() == size) {
m_region_lookup_cache.range = range;
m_region_lookup_cache.region = region;
return &region;
}
}
return nullptr;
}
Region* Process::find_region_containing(const Range& range)
{
ScopedSpinLock lock(m_lock);
for (auto& region : m_regions) {
if (region.contains(range))
return &region;
}
return nullptr;
}
void Process::kill_threads_except_self()
{
InterruptDisabler disabler;
@ -339,7 +235,7 @@ Process::Process(RefPtr<Thread>& first_thread, const String& name, uid_t uid, gi
{
dbgln_if(PROCESS_DEBUG, "Created new process {}({})", m_name, m_pid.value());
m_page_directory = PageDirectory::create_for_userspace(*this, fork_parent ? &fork_parent->page_directory().range_allocator() : nullptr);
m_space = Space::create(*this, fork_parent ? &fork_parent->space() : nullptr);
if (fork_parent) {
// NOTE: fork() doesn't clone all threads; the thread that called fork() becomes the only thread in the new process.
@ -365,28 +261,6 @@ Process::~Process()
}
}
void Process::dump_regions()
{
klog() << "Process regions:";
klog() << "BEGIN END SIZE ACCESS NAME";
ScopedSpinLock lock(m_lock);
Vector<Region*> sorted_regions;
sorted_regions.ensure_capacity(m_regions.size());
for (auto& region : m_regions)
sorted_regions.append(&region);
quick_sort(sorted_regions, [](auto& a, auto& b) {
return a->vaddr() < b->vaddr();
});
for (auto& sorted_region : sorted_regions) {
auto& region = *sorted_region;
klog() << String::format("%08x", region.vaddr().get()) << " -- " << String::format("%08x", region.vaddr().offset(region.size() - 1).get()) << " " << String::format("%08zx", region.size()) << " " << (region.is_readable() ? 'R' : ' ') << (region.is_writable() ? 'W' : ' ') << (region.is_executable() ? 'X' : ' ') << (region.is_shared() ? 'S' : ' ') << (region.is_stack() ? 'T' : ' ') << (region.vmobject().is_anonymous() ? 'A' : ' ') << " " << region.name().characters();
}
MM.dump_kernel_regions();
}
// Make sure the compiler doesn't "optimize away" this function:
extern void signal_trampoline_dummy();
void signal_trampoline_dummy()
@ -457,7 +331,7 @@ void Process::crash(int signal, u32 eip, bool out_of_memory)
}
m_termination_signal = signal;
set_dump_core(!out_of_memory);
dump_regions();
space().dump_regions();
ASSERT(is_user_process());
die();
// We can not return from here, as there is nowhere
@ -643,10 +517,7 @@ void Process::finalize()
unblock_waiters(Thread::WaitBlocker::UnblockFlags::Terminated);
{
ScopedSpinLock lock(m_lock);
m_regions.clear();
}
m_space->remove_all_regions({});
ASSERT(ref_count() > 0);
// WaitBlockCondition::finalize will be in charge of dropping the last
@ -689,8 +560,8 @@ size_t Process::amount_dirty_private() const
// The main issue I'm thinking of is when the VMObject has physical pages that none of the Regions are mapping.
// That's probably a situation that needs to be looked at in general.
size_t amount = 0;
ScopedSpinLock lock(m_lock);
for (auto& region : m_regions) {
ScopedSpinLock lock(space().get_lock());
for (auto& region : space().regions()) {
if (!region.is_shared())
amount += region.amount_dirty();
}
@ -701,8 +572,8 @@ size_t Process::amount_clean_inode() const
{
HashTable<const InodeVMObject*> vmobjects;
{
ScopedSpinLock lock(m_lock);
for (auto& region : m_regions) {
ScopedSpinLock lock(space().get_lock());
for (auto& region : space().regions()) {
if (region.vmobject().is_inode())
vmobjects.set(&static_cast<const InodeVMObject&>(region.vmobject()));
}
@ -716,8 +587,8 @@ size_t Process::amount_clean_inode() const
size_t Process::amount_virtual() const
{
size_t amount = 0;
ScopedSpinLock lock(m_lock);
for (auto& region : m_regions) {
ScopedSpinLock lock(space().get_lock());
for (auto& region : space().regions()) {
amount += region.size();
}
return amount;
@ -727,8 +598,8 @@ size_t Process::amount_resident() const
{
// FIXME: This will double count if multiple regions use the same physical page.
size_t amount = 0;
ScopedSpinLock lock(m_lock);
for (auto& region : m_regions) {
ScopedSpinLock lock(space().get_lock());
for (auto& region : space().regions()) {
amount += region.amount_resident();
}
return amount;
@ -741,8 +612,8 @@ size_t Process::amount_shared() const
// and each PhysicalPage is only reffed by its VMObject. This needs to be refactored
// so that every Region contributes +1 ref to each of its PhysicalPages.
size_t amount = 0;
ScopedSpinLock lock(m_lock);
for (auto& region : m_regions) {
ScopedSpinLock lock(space().get_lock());
for (auto& region : space().regions()) {
amount += region.amount_shared();
}
return amount;
@ -751,8 +622,8 @@ size_t Process::amount_shared() const
size_t Process::amount_purgeable_volatile() const
{
size_t amount = 0;
ScopedSpinLock lock(m_lock);
for (auto& region : m_regions) {
ScopedSpinLock lock(space().get_lock());
for (auto& region : space().regions()) {
if (region.vmobject().is_anonymous() && static_cast<const AnonymousVMObject&>(region.vmobject()).is_any_volatile())
amount += region.amount_resident();
}
@ -762,8 +633,8 @@ size_t Process::amount_purgeable_volatile() const
size_t Process::amount_purgeable_nonvolatile() const
{
size_t amount = 0;
ScopedSpinLock lock(m_lock);
for (auto& region : m_regions) {
ScopedSpinLock lock(space().get_lock());
for (auto& region : space().regions()) {
if (region.vmobject().is_anonymous() && !static_cast<const AnonymousVMObject&>(region.vmobject()).is_any_volatile())
amount += region.amount_resident();
}
@ -858,14 +729,6 @@ void Process::set_root_directory(const Custody& root)
m_root_directory = root;
}
Region& Process::add_region(NonnullOwnPtr<Region> region)
{
auto* ptr = region.ptr();
ScopedSpinLock lock(m_lock);
m_regions.append(move(region));
return *ptr;
}
void Process::set_tty(TTY* tty)
{
m_tty = tty;