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![Liav A](/assets/img/avatar_default.png)
We add this basic functionality to the Kernel so Userspace can request a particular virtual memory mapping to be immutable. This will be useful later on in the DynamicLoader code. The annotation of a particular Kernel Region as immutable implies that the following restrictions apply, so these features are prohibited: - Changing the region's protection bits - Unmapping the region - Annotating the region with other virtual memory flags - Applying further memory advises on the region - Changing the region name - Re-mapping the region
427 lines
16 KiB
C++
427 lines
16 KiB
C++
/*
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* Copyright (c) 2021-2022, Andreas Kling <kling@serenityos.org>
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* Copyright (c) 2021, Leon Albrecht <leon2002.la@gmail.com>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <Kernel/API/MemoryLayout.h>
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#include <Kernel/Arch/CPU.h>
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#include <Kernel/Locking/Spinlock.h>
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#include <Kernel/Memory/AddressSpace.h>
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#include <Kernel/Memory/AnonymousVMObject.h>
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#include <Kernel/Memory/InodeVMObject.h>
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#include <Kernel/Memory/MemoryManager.h>
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#include <Kernel/PerformanceManager.h>
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#include <Kernel/Process.h>
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#include <Kernel/Random.h>
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#include <Kernel/Scheduler.h>
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namespace Kernel::Memory {
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ErrorOr<NonnullOwnPtr<AddressSpace>> AddressSpace::try_create(AddressSpace const* parent)
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{
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auto page_directory = TRY(PageDirectory::try_create_for_userspace());
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VirtualRange total_range = [&]() -> VirtualRange {
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if (parent)
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return parent->m_region_tree.total_range();
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constexpr FlatPtr userspace_range_base = USER_RANGE_BASE;
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FlatPtr const userspace_range_ceiling = USER_RANGE_CEILING;
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size_t random_offset = (get_fast_random<u8>() % 2 * MiB) & PAGE_MASK;
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FlatPtr base = userspace_range_base + random_offset;
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return VirtualRange(VirtualAddress { base }, userspace_range_ceiling - base);
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}();
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auto space = TRY(adopt_nonnull_own_or_enomem(new (nothrow) AddressSpace(move(page_directory), total_range)));
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space->page_directory().set_space({}, *space);
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return space;
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}
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AddressSpace::AddressSpace(NonnullLockRefPtr<PageDirectory> page_directory, VirtualRange total_range)
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: m_page_directory(move(page_directory))
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, m_region_tree(total_range)
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{
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}
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AddressSpace::~AddressSpace() = default;
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ErrorOr<void> AddressSpace::unmap_mmap_range(VirtualAddress addr, size_t size)
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{
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if (!size)
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return EINVAL;
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auto range_to_unmap = TRY(VirtualRange::expand_to_page_boundaries(addr.get(), size));
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if (!is_user_range(range_to_unmap))
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return EFAULT;
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if (auto* whole_region = find_region_from_range(range_to_unmap)) {
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if (!whole_region->is_mmap())
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return EPERM;
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if (whole_region->is_immutable())
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return EPERM;
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PerformanceManager::add_unmap_perf_event(Process::current(), whole_region->range());
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deallocate_region(*whole_region);
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return {};
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}
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if (auto* old_region = find_region_containing(range_to_unmap)) {
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if (!old_region->is_mmap())
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return EPERM;
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if (old_region->is_immutable())
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return EPERM;
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// Remove the old region from our regions tree, since were going to add another region
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// with the exact same start address.
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auto region = take_region(*old_region);
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region->unmap();
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auto new_regions = TRY(try_split_region_around_range(*region, range_to_unmap));
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// And finally we map the new region(s) using our page directory (they were just allocated and don't have one).
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for (auto* new_region : new_regions) {
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// TODO: Ideally we should do this in a way that can be rolled back on failure, as failing here
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// leaves the caller in an undefined state.
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TRY(new_region->map(page_directory()));
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}
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PerformanceManager::add_unmap_perf_event(Process::current(), range_to_unmap);
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return {};
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}
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// Try again while checking multiple regions at a time.
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auto const& regions = TRY(find_regions_intersecting(range_to_unmap));
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if (regions.is_empty())
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return {};
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// Check if any of the regions is not mmap'ed, to not accidentally
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// error out with just half a region map left.
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for (auto* region : regions) {
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if (!region->is_mmap())
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return EPERM;
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if (region->is_immutable())
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return EPERM;
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}
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Vector<Region*, 2> new_regions;
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for (auto* old_region : regions) {
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// If it's a full match we can remove the entire old region.
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if (old_region->range().intersect(range_to_unmap).size() == old_region->size()) {
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deallocate_region(*old_region);
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continue;
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}
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// Remove the old region from our regions tree, since were going to add another region
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// with the exact same start address.
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auto region = take_region(*old_region);
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region->unmap();
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// Otherwise, split the regions and collect them for future mapping.
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auto split_regions = TRY(try_split_region_around_range(*region, range_to_unmap));
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TRY(new_regions.try_extend(split_regions));
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}
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// And finally map the new region(s) into our page directory.
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for (auto* new_region : new_regions) {
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// TODO: Ideally we should do this in a way that can be rolled back on failure, as failing here
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// leaves the caller in an undefined state.
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TRY(new_region->map(page_directory()));
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}
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PerformanceManager::add_unmap_perf_event(Process::current(), range_to_unmap);
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return {};
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}
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ErrorOr<Region*> AddressSpace::try_allocate_split_region(Region const& source_region, VirtualRange const& range, size_t offset_in_vmobject)
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{
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OwnPtr<KString> region_name;
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if (!source_region.name().is_null())
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region_name = TRY(KString::try_create(source_region.name()));
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auto new_region = TRY(Region::create_unplaced(
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source_region.vmobject(), offset_in_vmobject, move(region_name), source_region.access(), source_region.is_cacheable() ? Region::Cacheable::Yes : Region::Cacheable::No, source_region.is_shared()));
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new_region->set_syscall_region(source_region.is_syscall_region());
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new_region->set_mmap(source_region.is_mmap(), source_region.mmapped_from_readable(), source_region.mmapped_from_writable());
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new_region->set_stack(source_region.is_stack());
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size_t page_offset_in_source_region = (offset_in_vmobject - source_region.offset_in_vmobject()) / PAGE_SIZE;
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for (size_t i = 0; i < new_region->page_count(); ++i) {
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if (source_region.should_cow(page_offset_in_source_region + i))
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TRY(new_region->set_should_cow(i, true));
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}
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TRY(m_region_tree.place_specifically(*new_region, range));
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return new_region.leak_ptr();
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}
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ErrorOr<Region*> AddressSpace::allocate_region(RandomizeVirtualAddress randomize_virtual_address, VirtualAddress requested_address, size_t requested_size, size_t requested_alignment, StringView name, int prot, AllocationStrategy strategy)
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{
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if (!requested_address.is_page_aligned())
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return EINVAL;
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auto size = TRY(Memory::page_round_up(requested_size));
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auto alignment = TRY(Memory::page_round_up(requested_alignment));
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OwnPtr<KString> region_name;
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if (!name.is_null())
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region_name = TRY(KString::try_create(name));
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auto vmobject = TRY(AnonymousVMObject::try_create_with_size(size, strategy));
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auto region = TRY(Region::create_unplaced(move(vmobject), 0, move(region_name), prot_to_region_access_flags(prot)));
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if (requested_address.is_null()) {
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TRY(m_region_tree.place_anywhere(*region, randomize_virtual_address, size, alignment));
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} else {
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TRY(m_region_tree.place_specifically(*region, VirtualRange { requested_address, size }));
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}
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TRY(region->map(page_directory(), ShouldFlushTLB::No));
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return region.leak_ptr();
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}
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ErrorOr<Region*> AddressSpace::allocate_region_with_vmobject(VirtualRange requested_range, NonnullLockRefPtr<VMObject> vmobject, size_t offset_in_vmobject, StringView name, int prot, bool shared)
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{
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return allocate_region_with_vmobject(RandomizeVirtualAddress::Yes, requested_range.base(), requested_range.size(), PAGE_SIZE, move(vmobject), offset_in_vmobject, name, prot, shared);
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}
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ErrorOr<Region*> AddressSpace::allocate_region_with_vmobject(RandomizeVirtualAddress randomize_virtual_address, VirtualAddress requested_address, size_t requested_size, size_t requested_alignment, NonnullLockRefPtr<VMObject> vmobject, size_t offset_in_vmobject, StringView name, int prot, bool shared)
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{
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if (!requested_address.is_page_aligned())
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return EINVAL;
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auto size = TRY(page_round_up(requested_size));
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auto alignment = TRY(page_round_up(requested_alignment));
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if (Checked<size_t>::addition_would_overflow(offset_in_vmobject, requested_size))
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return EOVERFLOW;
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size_t end_in_vmobject = offset_in_vmobject + requested_size;
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if (offset_in_vmobject >= vmobject->size()) {
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dbgln("allocate_region_with_vmobject: Attempt to allocate a region with an offset past the end of its VMObject.");
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return EINVAL;
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}
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if (end_in_vmobject > vmobject->size()) {
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dbgln("allocate_region_with_vmobject: Attempt to allocate a region with an end past the end of its VMObject.");
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return EINVAL;
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}
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offset_in_vmobject &= PAGE_MASK;
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OwnPtr<KString> region_name;
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if (!name.is_null())
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region_name = TRY(KString::try_create(name));
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auto region = TRY(Region::create_unplaced(move(vmobject), offset_in_vmobject, move(region_name), prot_to_region_access_flags(prot), Region::Cacheable::Yes, shared));
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if (requested_address.is_null())
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TRY(m_region_tree.place_anywhere(*region, randomize_virtual_address, size, alignment));
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else
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TRY(m_region_tree.place_specifically(*region, VirtualRange { VirtualAddress { requested_address }, size }));
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ArmedScopeGuard remove_region_from_tree_on_failure = [&] {
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// At this point the region is already part of the Process region tree, so we have to make sure
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// we remove it from the tree before returning an error, or else the Region tree will contain
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// a dangling pointer to the free'd Region instance
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m_region_tree.remove(*region);
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};
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if (prot == PROT_NONE) {
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// For PROT_NONE mappings, we don't have to set up any page table mappings.
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// We do still need to attach the region to the page_directory though.
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region->set_page_directory(page_directory());
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} else {
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TRY(region->map(page_directory(), ShouldFlushTLB::No));
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}
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remove_region_from_tree_on_failure.disarm();
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return region.leak_ptr();
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}
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void AddressSpace::deallocate_region(Region& region)
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{
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(void)take_region(region);
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}
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NonnullOwnPtr<Region> AddressSpace::take_region(Region& region)
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{
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auto did_remove = m_region_tree.remove(region);
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VERIFY(did_remove);
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return NonnullOwnPtr { NonnullOwnPtr<Region>::Adopt, region };
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}
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Region* AddressSpace::find_region_from_range(VirtualRange const& range)
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{
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auto* found_region = m_region_tree.regions().find(range.base().get());
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if (!found_region)
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return nullptr;
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auto& region = *found_region;
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auto rounded_range_size = page_round_up(range.size());
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if (rounded_range_size.is_error() || region.size() != rounded_range_size.value())
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return nullptr;
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return ®ion;
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}
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Region* AddressSpace::find_region_containing(VirtualRange const& range)
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{
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return m_region_tree.find_region_containing(range);
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}
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ErrorOr<Vector<Region*, 4>> AddressSpace::find_regions_intersecting(VirtualRange const& range)
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{
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Vector<Region*, 4> regions = {};
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size_t total_size_collected = 0;
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auto* found_region = m_region_tree.regions().find_largest_not_above(range.base().get());
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if (!found_region)
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return regions;
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for (auto iter = m_region_tree.regions().begin_from(*found_region); !iter.is_end(); ++iter) {
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auto const& iter_range = (*iter).range();
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if (iter_range.base() < range.end() && iter_range.end() > range.base()) {
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TRY(regions.try_append(&*iter));
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total_size_collected += (*iter).size() - iter_range.intersect(range).size();
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if (total_size_collected == range.size())
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break;
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}
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}
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return regions;
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}
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// Carve out a virtual address range from a region and return the two regions on either side
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ErrorOr<Vector<Region*, 2>> AddressSpace::try_split_region_around_range(Region const& source_region, VirtualRange const& desired_range)
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{
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VirtualRange old_region_range = source_region.range();
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auto remaining_ranges_after_unmap = old_region_range.carve(desired_range);
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VERIFY(!remaining_ranges_after_unmap.is_empty());
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auto try_make_replacement_region = [&](VirtualRange const& new_range) -> ErrorOr<Region*> {
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VERIFY(old_region_range.contains(new_range));
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size_t new_range_offset_in_vmobject = source_region.offset_in_vmobject() + (new_range.base().get() - old_region_range.base().get());
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return try_allocate_split_region(source_region, new_range, new_range_offset_in_vmobject);
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};
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Vector<Region*, 2> new_regions;
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for (auto& new_range : remaining_ranges_after_unmap) {
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auto* new_region = TRY(try_make_replacement_region(new_range));
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new_regions.unchecked_append(new_region);
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}
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return new_regions;
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}
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void AddressSpace::dump_regions()
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{
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dbgln("Process regions:");
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#if ARCH(I386)
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char const* addr_padding = "";
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#else
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char const* addr_padding = " ";
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#endif
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dbgln("BEGIN{} END{} SIZE{} ACCESS NAME",
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addr_padding, addr_padding, addr_padding);
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for (auto const& region : m_region_tree.regions()) {
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dbgln("{:p} -- {:p} {:p} {:c}{:c}{:c}{:c}{:c}{:c} {}", region.vaddr().get(), region.vaddr().offset(region.size() - 1).get(), region.size(),
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region.is_readable() ? 'R' : ' ',
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region.is_writable() ? 'W' : ' ',
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region.is_executable() ? 'X' : ' ',
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region.is_shared() ? 'S' : ' ',
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region.is_stack() ? 'T' : ' ',
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region.is_syscall_region() ? 'C' : ' ',
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region.name());
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}
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MM.dump_kernel_regions();
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}
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void AddressSpace::remove_all_regions(Badge<Process>)
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{
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VERIFY(Thread::current() == g_finalizer);
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{
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SpinlockLocker pd_locker(m_page_directory->get_lock());
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for (auto& region : m_region_tree.regions())
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region.unmap_with_locks_held(ShouldFlushTLB::No, pd_locker);
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}
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m_region_tree.delete_all_regions_assuming_they_are_unmapped();
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}
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size_t AddressSpace::amount_dirty_private() const
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{
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// FIXME: This gets a bit more complicated for Regions sharing the same underlying VMObject.
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// The main issue I'm thinking of is when the VMObject has physical pages that none of the Regions are mapping.
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// That's probably a situation that needs to be looked at in general.
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size_t amount = 0;
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for (auto const& region : m_region_tree.regions()) {
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if (!region.is_shared())
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amount += region.amount_dirty();
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}
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return amount;
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}
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ErrorOr<size_t> AddressSpace::amount_clean_inode() const
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{
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HashTable<LockRefPtr<InodeVMObject>> vmobjects;
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for (auto const& region : m_region_tree.regions()) {
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if (region.vmobject().is_inode())
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TRY(vmobjects.try_set(&static_cast<InodeVMObject const&>(region.vmobject())));
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}
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size_t amount = 0;
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for (auto& vmobject : vmobjects)
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amount += vmobject->amount_clean();
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return amount;
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}
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size_t AddressSpace::amount_virtual() const
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{
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size_t amount = 0;
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for (auto const& region : m_region_tree.regions()) {
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amount += region.size();
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}
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return amount;
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}
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size_t AddressSpace::amount_resident() const
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{
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// FIXME: This will double count if multiple regions use the same physical page.
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size_t amount = 0;
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for (auto const& region : m_region_tree.regions()) {
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amount += region.amount_resident();
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}
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return amount;
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}
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size_t AddressSpace::amount_shared() const
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{
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// FIXME: This will double count if multiple regions use the same physical page.
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// FIXME: It doesn't work at the moment, since it relies on PhysicalPage ref counts,
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// and each PhysicalPage is only reffed by its VMObject. This needs to be refactored
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// so that every Region contributes +1 ref to each of its PhysicalPages.
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size_t amount = 0;
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for (auto const& region : m_region_tree.regions()) {
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amount += region.amount_shared();
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}
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return amount;
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}
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size_t AddressSpace::amount_purgeable_volatile() const
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{
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size_t amount = 0;
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for (auto const& region : m_region_tree.regions()) {
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if (!region.vmobject().is_anonymous())
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continue;
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auto const& vmobject = static_cast<AnonymousVMObject const&>(region.vmobject());
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if (vmobject.is_purgeable() && vmobject.is_volatile())
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amount += region.amount_resident();
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}
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return amount;
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}
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size_t AddressSpace::amount_purgeable_nonvolatile() const
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{
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size_t amount = 0;
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for (auto const& region : m_region_tree.regions()) {
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if (!region.vmobject().is_anonymous())
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continue;
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auto const& vmobject = static_cast<AnonymousVMObject const&>(region.vmobject());
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if (vmobject.is_purgeable() && !vmobject.is_volatile())
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amount += region.amount_resident();
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}
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return amount;
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}
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}
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