/*
 * Copyright (c) 2018-2020 Atmosphère-NX
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
#include <mesosphere.hpp>
#include <mesosphere/kern_select_page_table.hpp>

namespace ams::kern {

    Result KPageTableBase::InitializeForKernel(bool is_64_bit, void *table, KVirtualAddress start, KVirtualAddress end) {
        /* Initialize our members. */
        this->address_space_width           = (is_64_bit) ? BITSIZEOF(u64) : BITSIZEOF(u32);
        this->address_space_start           = KProcessAddress(GetInteger(start));
        this->address_space_end             = KProcessAddress(GetInteger(end));
        this->is_kernel                     = true;
        this->enable_aslr                   = true;

        this->heap_region_start             = 0;
        this->heap_region_end               = 0;
        this->current_heap_end              = 0;
        this->alias_region_start            = 0;
        this->alias_region_end              = 0;
        this->stack_region_start            = 0;
        this->stack_region_end              = 0;
        this->kernel_map_region_start       = 0;
        this->kernel_map_region_end         = 0;
        this->alias_code_region_start       = 0;
        this->alias_code_region_end         = 0;
        this->code_region_start             = 0;
        this->code_region_end               = 0;
        this->max_heap_size                 = 0;
        this->mapped_physical_memory_size   = 0;
        this->mapped_unsafe_physical_memory = 0;

        this->memory_block_slab_manager     = std::addressof(Kernel::GetSystemMemoryBlockManager());
        this->block_info_manager            = std::addressof(Kernel::GetBlockInfoManager());

        this->allocate_option               = KMemoryManager::EncodeOption(KMemoryManager::Pool_System, KMemoryManager::Direction_FromFront);
        this->heap_fill_value               = MemoryFillValue_Zero;
        this->ipc_fill_value                = MemoryFillValue_Zero;
        this->stack_fill_value              = MemoryFillValue_Zero;

        this->cached_physical_linear_region = nullptr;
        this->cached_physical_heap_region   = nullptr;
        this->cached_virtual_heap_region    = nullptr;

        /* Initialize our implementation. */
        this->impl.InitializeForKernel(table, start, end);

        /* Initialize our memory block manager. */
        return this->memory_block_manager.Initialize(this->address_space_start, this->address_space_end, this->memory_block_slab_manager);

        return ResultSuccess();
    }

    Result KPageTableBase::InitializeForProcess(ams::svc::CreateProcessFlag as_type, bool enable_aslr, bool from_back, KMemoryManager::Pool pool, void *table, KProcessAddress start, KProcessAddress end, KProcessAddress code_address, size_t code_size, KMemoryBlockSlabManager *mem_block_slab_manager, KBlockInfoManager *block_info_manager) {
        /* Validate the region. */
        MESOSPHERE_ABORT_UNLESS(start <= code_address);
        MESOSPHERE_ABORT_UNLESS(code_address < code_address + code_size);
        MESOSPHERE_ABORT_UNLESS(code_address + code_size - 1 <= end - 1);

        /* Declare variables to hold our region sizes. */

        /* Define helpers. */
        auto GetSpaceStart = [&](KAddressSpaceInfo::Type type) ALWAYS_INLINE_LAMBDA {
            return KAddressSpaceInfo::GetAddressSpaceStart(this->address_space_width, type);
        };
        auto GetSpaceSize = [&](KAddressSpaceInfo::Type type) ALWAYS_INLINE_LAMBDA {
            return KAddressSpaceInfo::GetAddressSpaceSize(this->address_space_width, type);
        };

        /* Set our width and heap/alias sizes. */
        this->address_space_width = GetAddressSpaceWidth(as_type);
        size_t alias_region_size  = GetSpaceSize(KAddressSpaceInfo::Type_Alias);
        size_t heap_region_size   = GetSpaceSize(KAddressSpaceInfo::Type_Heap);

        /* Adjust heap/alias size if we don't have an alias region. */
        if ((as_type & ams::svc::CreateProcessFlag_AddressSpaceMask) == ams::svc::CreateProcessFlag_AddressSpace32BitWithoutAlias) {
            heap_region_size += alias_region_size;
            alias_region_size = 0;
        }

        /* Set code regions and determine remaining sizes. */
        KProcessAddress process_code_start;
        KProcessAddress process_code_end;
        size_t stack_region_size;
        size_t kernel_map_region_size;
        if (this->address_space_width == 39) {
            alias_region_size               = GetSpaceSize(KAddressSpaceInfo::Type_Alias);
            heap_region_size                = GetSpaceSize(KAddressSpaceInfo::Type_Heap);
            stack_region_size               = GetSpaceSize(KAddressSpaceInfo::Type_Stack);
            kernel_map_region_size          = GetSpaceSize(KAddressSpaceInfo::Type_32Bit);
            this->code_region_start         = GetSpaceStart(KAddressSpaceInfo::Type_Large64Bit);
            this->code_region_end           = this->code_region_start + GetSpaceSize(KAddressSpaceInfo::Type_Large64Bit);
            this->alias_code_region_start   = this->code_region_start;
            this->alias_code_region_end     = this->code_region_end;
            process_code_start              = util::AlignDown(GetInteger(code_address), RegionAlignment);
            process_code_end                = util::AlignUp(GetInteger(code_address) + code_size, RegionAlignment);
        } else {
            stack_region_size               = 0;
            kernel_map_region_size          = 0;
            this->code_region_start         = GetSpaceStart(KAddressSpaceInfo::Type_32Bit);
            this->code_region_end           = this->code_region_start + GetSpaceSize(KAddressSpaceInfo::Type_32Bit);
            this->stack_region_start        = this->code_region_start;
            this->alias_code_region_start   = this->code_region_start;
            this->alias_code_region_end     = GetSpaceStart(KAddressSpaceInfo::Type_Small64Bit) + GetSpaceSize(KAddressSpaceInfo::Type_Small64Bit);
            this->stack_region_end          = this->code_region_end;
            this->kernel_map_region_start   = this->code_region_start;
            this->kernel_map_region_end     = this->code_region_end;
            process_code_start              = this->code_region_start;
            process_code_end                = this->code_region_end;
        }

        /* Set other basic fields. */
        this->enable_aslr               = enable_aslr;
        this->address_space_start       = start;
        this->address_space_end         = end;
        this->is_kernel                 = false;
        this->memory_block_slab_manager = mem_block_slab_manager;
        this->block_info_manager        = block_info_manager;

        /* Determine the region we can place our undetermineds in. */
        KProcessAddress alloc_start;
        size_t alloc_size;
        if ((GetInteger(process_code_start) - GetInteger(this->code_region_start)) >= (GetInteger(end) - GetInteger(process_code_end))) {
            alloc_start = this->code_region_start;
            alloc_size  = GetInteger(process_code_start) - GetInteger(this->code_region_start);
        } else {
            alloc_start = process_code_end;
            alloc_size  = GetInteger(end) - GetInteger(process_code_end);
        }
        const size_t needed_size = (alias_region_size + heap_region_size + stack_region_size + kernel_map_region_size);
        R_UNLESS(alloc_size >= needed_size, svc::ResultOutOfMemory());

        const size_t remaining_size = alloc_size - needed_size;

        /* Determine random placements for each region. */
        size_t alias_rnd = 0, heap_rnd = 0, stack_rnd = 0, kmap_rnd = 0;
        if (enable_aslr) {
            alias_rnd = KSystemControl::GenerateRandomRange(0, remaining_size / RegionAlignment) * RegionAlignment;
            heap_rnd  = KSystemControl::GenerateRandomRange(0, remaining_size / RegionAlignment) * RegionAlignment;
            stack_rnd = KSystemControl::GenerateRandomRange(0, remaining_size / RegionAlignment) * RegionAlignment;
            kmap_rnd  = KSystemControl::GenerateRandomRange(0, remaining_size / RegionAlignment) * RegionAlignment;
        }

        /* Setup heap and alias regions. */
        this->alias_region_start = alloc_start + alias_rnd;
        this->alias_region_end   = this->alias_region_start + alias_region_size;
        this->heap_region_start  = alloc_start + heap_rnd;
        this->heap_region_end    = this->heap_region_start + heap_region_size;

        if (alias_rnd <= heap_rnd) {
            this->heap_region_start  += alias_region_size;
            this->heap_region_end    += alias_region_size;
        } else {
            this->alias_region_start += heap_region_size;
            this->alias_region_end   += heap_region_size;
        }

        /* Setup stack region. */
        if (stack_region_size) {
            this->stack_region_start = alloc_start + stack_rnd;
            this->stack_region_end   = this->stack_region_start + stack_region_size;

            if (alias_rnd < stack_rnd) {
                this->stack_region_start += alias_region_size;
                this->stack_region_end   += alias_region_size;
            } else {
                this->alias_region_start += stack_region_size;
                this->alias_region_end   += stack_region_size;
            }

            if (heap_rnd < stack_rnd) {
                this->stack_region_start += heap_region_size;
                this->stack_region_end   += heap_region_size;
            } else {
                this->heap_region_start  += stack_region_size;
                this->heap_region_end    += stack_region_size;
            }
        }

        /* Setup kernel map region. */
        if (kernel_map_region_size) {
            this->kernel_map_region_start = alloc_start + kmap_rnd;
            this->kernel_map_region_end   = this->kernel_map_region_start + kernel_map_region_size;

            if (alias_rnd < kmap_rnd) {
                this->kernel_map_region_start += alias_region_size;
                this->kernel_map_region_end   += alias_region_size;
            } else {
                this->alias_region_start      += kernel_map_region_size;
                this->alias_region_end        += kernel_map_region_size;
            }

            if (heap_rnd < kmap_rnd) {
                this->kernel_map_region_start += heap_region_size;
                this->kernel_map_region_end   += heap_region_size;
            } else {
                this->heap_region_start       += kernel_map_region_size;
                this->heap_region_end         += kernel_map_region_size;
            }

            if (stack_region_size) {
                if (stack_rnd < kmap_rnd) {
                    this->kernel_map_region_start += stack_region_size;
                    this->kernel_map_region_end   += stack_region_size;
                } else {
                    this->stack_region_start      += kernel_map_region_size;
                    this->stack_region_end        += kernel_map_region_size;
                }
            }
        }

        /* Set heap and fill members. */
        this->current_heap_end              = this->heap_region_start;
        this->max_heap_size                 = 0;
        this->mapped_physical_memory_size    = 0;
        this->mapped_unsafe_physical_memory = 0;

        const bool fill_memory = KTargetSystem::IsDebugMemoryFillEnabled();
        this->heap_fill_value  = fill_memory ? MemoryFillValue_Heap  : MemoryFillValue_Zero;
        this->ipc_fill_value   = fill_memory ? MemoryFillValue_Ipc   : MemoryFillValue_Zero;
        this->stack_fill_value = fill_memory ? MemoryFillValue_Stack : MemoryFillValue_Zero;

        /* Set allocation option. */
        this->allocate_option = KMemoryManager::EncodeOption(pool, from_back ? KMemoryManager::Direction_FromBack : KMemoryManager::Direction_FromFront);

        /* Ensure that we regions inside our address space. */
        auto IsInAddressSpace = [&](KProcessAddress addr) ALWAYS_INLINE_LAMBDA { return this->address_space_start <= addr && addr <= this->address_space_end; };
        MESOSPHERE_ABORT_UNLESS(IsInAddressSpace(this->alias_region_start));
        MESOSPHERE_ABORT_UNLESS(IsInAddressSpace(this->alias_region_end));
        MESOSPHERE_ABORT_UNLESS(IsInAddressSpace(this->heap_region_start));
        MESOSPHERE_ABORT_UNLESS(IsInAddressSpace(this->heap_region_end));
        MESOSPHERE_ABORT_UNLESS(IsInAddressSpace(this->stack_region_start));
        MESOSPHERE_ABORT_UNLESS(IsInAddressSpace(this->stack_region_end));
        MESOSPHERE_ABORT_UNLESS(IsInAddressSpace(this->kernel_map_region_start));
        MESOSPHERE_ABORT_UNLESS(IsInAddressSpace(this->kernel_map_region_end));

        /* Ensure that we selected regions that don't overlap. */
        const KProcessAddress alias_start = this->alias_region_start;
        const KProcessAddress alias_last  = this->alias_region_end - 1;
        const KProcessAddress heap_start  = this->heap_region_start;
        const KProcessAddress heap_last   = this->heap_region_end - 1;
        const KProcessAddress stack_start = this->stack_region_start;
        const KProcessAddress stack_last  = this->stack_region_end - 1;
        const KProcessAddress kmap_start  = this->kernel_map_region_start;
        const KProcessAddress kmap_last   = this->kernel_map_region_end - 1;
        MESOSPHERE_ABORT_UNLESS(alias_last < heap_start  || heap_last  < alias_start);
        MESOSPHERE_ABORT_UNLESS(alias_last < stack_start || stack_last < alias_start);
        MESOSPHERE_ABORT_UNLESS(alias_last < kmap_start  || kmap_last  < alias_start);
        MESOSPHERE_ABORT_UNLESS(heap_last  < stack_start || stack_last < heap_start);
        MESOSPHERE_ABORT_UNLESS(heap_last  < kmap_start  || kmap_last  < heap_start);

        /* Initialize our implementation. */
        this->impl.InitializeForProcess(table, GetInteger(start), GetInteger(end));

        /* Initialize our memory block manager. */
        return this->memory_block_manager.Initialize(this->address_space_start, this->address_space_end, this->memory_block_slab_manager);

        return ResultSuccess();
    }


    void KPageTableBase::Finalize() {
        this->memory_block_manager.Finalize(this->memory_block_slab_manager);
        MESOSPHERE_TODO("cpu::InvalidateEntireInstructionCache();");
    }

    KProcessAddress KPageTableBase::GetRegionAddress(KMemoryState state) const {
        switch (state) {
            case KMemoryState_Free:
            case KMemoryState_Kernel:
                return this->address_space_start;
            case KMemoryState_Normal:
                return this->heap_region_start;
            case KMemoryState_Ipc:
            case KMemoryState_NonSecureIpc:
            case KMemoryState_NonDeviceIpc:
                return this->alias_region_start;
            case KMemoryState_Stack:
                return this->stack_region_start;
            case KMemoryState_Io:
            case KMemoryState_Static:
            case KMemoryState_ThreadLocal:
                return this->kernel_map_region_start;
            case KMemoryState_Shared:
            case KMemoryState_AliasCode:
            case KMemoryState_AliasCodeData:
            case KMemoryState_Transfered:
            case KMemoryState_SharedTransfered:
            case KMemoryState_SharedCode:
            case KMemoryState_GeneratedCode:
            case KMemoryState_CodeOut:
                return this->alias_code_region_start;
            case KMemoryState_Code:
            case KMemoryState_CodeData:
                return this->code_region_start;
            MESOSPHERE_UNREACHABLE_DEFAULT_CASE();
        }
    }

    size_t KPageTableBase::GetRegionSize(KMemoryState state) const {
        switch (state) {
            case KMemoryState_Free:
            case KMemoryState_Kernel:
                return this->address_space_end - this->address_space_start;
            case KMemoryState_Normal:
                return this->heap_region_end - this->heap_region_start;
            case KMemoryState_Ipc:
            case KMemoryState_NonSecureIpc:
            case KMemoryState_NonDeviceIpc:
                return this->alias_region_end - this->alias_region_start;
            case KMemoryState_Stack:
                return this->stack_region_end - this->stack_region_start;
            case KMemoryState_Io:
            case KMemoryState_Static:
            case KMemoryState_ThreadLocal:
                return this->kernel_map_region_end - this->kernel_map_region_start;
            case KMemoryState_Shared:
            case KMemoryState_AliasCode:
            case KMemoryState_AliasCodeData:
            case KMemoryState_Transfered:
            case KMemoryState_SharedTransfered:
            case KMemoryState_SharedCode:
            case KMemoryState_GeneratedCode:
            case KMemoryState_CodeOut:
                return this->alias_code_region_end - this->alias_code_region_start;
            case KMemoryState_Code:
            case KMemoryState_CodeData:
                return this->code_region_end - this->code_region_start;
            MESOSPHERE_UNREACHABLE_DEFAULT_CASE();
        }
    }

    bool KPageTableBase::CanContain(KProcessAddress addr, size_t size, KMemoryState state) const {
        const KProcessAddress end = addr + size;
        const KProcessAddress last = end - 1;

        const KProcessAddress region_start = this->GetRegionAddress(state);
        const size_t region_size           = this->GetRegionSize(state);

        const bool is_in_region = region_start <= addr && addr < end && last <= region_start + region_size - 1;
        const bool is_in_heap   = !(end <= this->heap_region_start || this->heap_region_end <= addr);
        const bool is_in_alias  = !(end <= this->alias_region_start || this->alias_region_end <= addr);
        switch (state) {
            case KMemoryState_Free:
            case KMemoryState_Kernel:
                return is_in_region;
            case KMemoryState_Io:
            case KMemoryState_Static:
            case KMemoryState_Code:
            case KMemoryState_CodeData:
            case KMemoryState_Shared:
            case KMemoryState_AliasCode:
            case KMemoryState_AliasCodeData:
            case KMemoryState_Stack:
            case KMemoryState_ThreadLocal:
            case KMemoryState_Transfered:
            case KMemoryState_SharedTransfered:
            case KMemoryState_SharedCode:
            case KMemoryState_GeneratedCode:
            case KMemoryState_CodeOut:
                return is_in_region && !is_in_heap && !is_in_alias;
            case KMemoryState_Normal:
                MESOSPHERE_ASSERT(is_in_heap);
                return is_in_region && !is_in_alias;
            case KMemoryState_Ipc:
            case KMemoryState_NonSecureIpc:
            case KMemoryState_NonDeviceIpc:
                MESOSPHERE_ASSERT(is_in_alias);
                return is_in_region && !is_in_heap;
            default:
                return false;
        }
    }

    Result KPageTableBase::CheckMemoryState(const KMemoryInfo &info, u32 state_mask, u32 state, u32 perm_mask, u32 perm, u32 attr_mask, u32 attr) const {
        /* Validate the states match expectation. */
        R_UNLESS((info.state     & state_mask) == state, svc::ResultInvalidCurrentMemory());
        R_UNLESS((info.perm      & perm_mask)  == perm, svc::ResultInvalidCurrentMemory());
        R_UNLESS((info.attribute & attr_mask)  == attr, svc::ResultInvalidCurrentMemory());

        return ResultSuccess();
    }

    Result KPageTableBase::CheckMemoryState(KMemoryState *out_state, KMemoryPermission *out_perm, KMemoryAttribute *out_attr, KProcessAddress addr, size_t size, u32 state_mask, u32 state, u32 perm_mask, u32 perm, u32 attr_mask, u32 attr, u32 ignore_attr) const {
        MESOSPHERE_ASSERT(this->IsLockedByCurrentThread());

        /* Get information about the first block. */
        const KProcessAddress last_addr = addr + size - 1;
        KMemoryBlockManager::const_iterator it = this->memory_block_manager.FindIterator(addr);
        KMemoryInfo info = it->GetMemoryInfo();

        /* Validate all blocks in the range have correct state. */
        const KMemoryState      first_state = info.state;
        const KMemoryPermission first_perm  = info.perm;
        const KMemoryAttribute  first_attr  = info.attribute;
        while (true) {
            /* Validate the current block. */
            R_UNLESS(info.state == first_state,                                    svc::ResultInvalidCurrentMemory());
            R_UNLESS(info.perm  == first_perm,                                     svc::ResultInvalidCurrentMemory());
            R_UNLESS((info.attribute | ignore_attr) == (first_attr | ignore_attr), svc::ResultInvalidCurrentMemory());

            /* Validate against the provided masks. */
            R_TRY(this->CheckMemoryState(info, state_mask, state, perm_mask, perm, attr_mask, attr));

            /* Break once we're done. */
            if (last_addr <= info.GetLastAddress()) {
                break;
            }

            /* Advance our iterator. */
            it++;
            MESOSPHERE_ASSERT(it != this->memory_block_manager.cend());
            info = it->GetMemoryInfo();
        }

        /* Write output state. */
        if (out_state) {
            *out_state = first_state;
        }
        if (out_perm) {
            *out_perm = first_perm;
        }
        if (out_attr) {
            *out_attr = static_cast<KMemoryAttribute>(first_attr & ~ignore_attr);
        }
        return ResultSuccess();
    }

    Result KPageTableBase::UnlockMemory(KProcessAddress addr, size_t size, u32 state_mask, u32 state, u32 perm_mask, u32 perm, u32 attr_mask, u32 attr, KMemoryPermission new_perm, u32 lock_attr, const KPageGroup *pg) {
        /* Validate basic preconditions. */
        MESOSPHERE_ASSERT((attr_mask & lock_attr) == lock_attr);
        MESOSPHERE_ASSERT((attr      & lock_attr) == lock_attr);

        /* Validate the unlock request. */
        const size_t num_pages = size / PageSize;
        R_UNLESS(this->Contains(addr, size), svc::ResultInvalidCurrentMemory());

        /* Lock the table. */
        KScopedLightLock lk(this->general_lock);

        /* Check the state. */
        KMemoryState old_state;
        KMemoryPermission old_perm;
        KMemoryAttribute old_attr;
        R_TRY(this->CheckMemoryState(std::addressof(old_state), std::addressof(old_perm), std::addressof(old_attr), addr, size, state_mask | KMemoryState_FlagReferenceCounted, state | KMemoryState_FlagReferenceCounted, perm_mask, perm, attr_mask, attr));

        /* Check the page group. */
        if (pg != nullptr) {
            R_UNLESS(this->IsValidPageGroup(*pg, addr, num_pages), svc::ResultInvalidMemoryRegion());
        }

        /* Decide on new perm and attr. */
        new_perm = (new_perm != KMemoryPermission_None) ? new_perm : old_perm;
        KMemoryAttribute new_attr = static_cast<KMemoryAttribute>(old_attr & ~lock_attr);

        /* Create an update allocator. */
        KMemoryBlockManagerUpdateAllocator allocator(this->memory_block_slab_manager);
        R_TRY(allocator.GetResult());

        /* Update permission, if we need to. */
        if (new_perm != old_perm) {
            /* We're going to perform an update, so create a helper. */
            KScopedPageTableUpdater updater(this);

            const KPageProperties properties = { new_perm, false, (old_attr & KMemoryAttribute_Uncached) != 0, false };
            R_TRY(this->Operate(updater.GetPageList(), addr, num_pages, Null<KPhysicalAddress>, false, properties, OperationType_ChangePermissions, false));
        }

        /* Apply the memory block updates. */
        this->memory_block_manager.Update(std::addressof(allocator), addr, num_pages, old_state, new_perm, new_attr);

        return ResultSuccess();
    }

    Result KPageTableBase::QueryInfoImpl(KMemoryInfo *out_info, ams::svc::PageInfo *out_page, KProcessAddress address) const {
        MESOSPHERE_ASSERT(this->IsLockedByCurrentThread());
        MESOSPHERE_ASSERT(out_info != nullptr);
        MESOSPHERE_ASSERT(out_page != nullptr);

        const KMemoryBlock *block = this->memory_block_manager.FindBlock(address);
        R_UNLESS(block != nullptr, svc::ResultInvalidCurrentMemory());

        *out_info = block->GetMemoryInfo();
        out_page->flags = 0;
        return ResultSuccess();
    }

    Result KPageTableBase::MapMemory(KProcessAddress dst_address, KProcessAddress src_address, size_t size) {
        /* Lock the table. */
        KScopedLightLock lk(this->general_lock);

        /* Validate that the source address's state is valid. */
        KMemoryState src_state;
        R_TRY(this->CheckMemoryState(std::addressof(src_state), nullptr, nullptr, src_address, size, KMemoryState_FlagCanAlias, KMemoryState_FlagCanAlias, KMemoryPermission_All, KMemoryPermission_UserReadWrite, KMemoryAttribute_All, KMemoryAttribute_None));

        /* Validate that the dst address's state is valid. */
        R_TRY(this->CheckMemoryState(dst_address, size, KMemoryState_All, KMemoryState_Free, KMemoryPermission_None, KMemoryPermission_None, KMemoryAttribute_None, KMemoryAttribute_None));

        /* Create an update allocator for the source. */
        KMemoryBlockManagerUpdateAllocator src_allocator(this->memory_block_slab_manager);
        R_TRY(src_allocator.GetResult());

        /* Create an update allocator for the destination. */
        KMemoryBlockManagerUpdateAllocator dst_allocator(this->memory_block_slab_manager);
        R_TRY(dst_allocator.GetResult());

        /* Map the memory. */
        {
            /* Determine the number of pages being operated on. */
            const size_t num_pages = size / PageSize;

            /* Create page groups for the memory being unmapped. */
            KPageGroup pg(this->block_info_manager);

            /* Create the page group representing the source. */
            R_TRY(this->MakePageGroup(pg, src_address, num_pages));

            /* We're going to perform an update, so create a helper. */
            KScopedPageTableUpdater updater(this);

            /* Reprotect the source as kernel-read/not mapped. */
            const KMemoryPermission new_src_perm = static_cast<KMemoryPermission>(KMemoryPermission_KernelRead | KMemoryPermission_NotMapped);
            const KMemoryAttribute  new_src_attr = static_cast<KMemoryAttribute>(KMemoryAttribute_AnyLocked | KMemoryAttribute_Locked);
            const KPageProperties src_properties = { new_src_perm, false, false, false };
            R_TRY(this->Operate(updater.GetPageList(), src_address, num_pages, Null<KPhysicalAddress>, false, src_properties, OperationType_ChangePermissions, false));

            /* Ensure that we unprotect the source pages on failure. */
            auto unprot_guard = SCOPE_GUARD {
                const KPageProperties unprotect_properties = { KMemoryPermission_UserReadWrite, false, false, false };
                MESOSPHERE_R_ABORT_UNLESS(this->Operate(updater.GetPageList(), src_address, num_pages, Null<KPhysicalAddress>, false, unprotect_properties, OperationType_ChangePermissions, true));
            };

            /* Map the alias pages. */
            const KPageProperties dst_map_properties = { KMemoryPermission_UserReadWrite, false, false, false };
            R_TRY(this->MapPageGroupImpl(updater.GetPageList(), dst_address, pg, dst_map_properties, false));

            /* We successfully mapped the alias pages, so we don't need to unprotect the src pages on failure. */
            unprot_guard.Cancel();

            /* Apply the memory block updates. */
            this->memory_block_manager.Update(std::addressof(src_allocator), src_address, num_pages, src_state, new_src_perm, new_src_attr);
            this->memory_block_manager.Update(std::addressof(dst_allocator), dst_address, num_pages, KMemoryState_None, KMemoryPermission_UserReadWrite, KMemoryAttribute_None);
        }

        return ResultSuccess();
    }

    Result KPageTableBase::UnmapMemory(KProcessAddress dst_address, KProcessAddress src_address, size_t size) {
        /* Lock the table. */
        KScopedLightLock lk(this->general_lock);

        /* Validate that the source address's state is valid. */
        KMemoryState src_state;
        R_TRY(this->CheckMemoryState(std::addressof(src_state), nullptr, nullptr, src_address, size, KMemoryState_FlagCanAlias, KMemoryState_FlagCanAlias, KMemoryPermission_All, KMemoryPermission_NotMapped | KMemoryPermission_KernelRead, KMemoryAttribute_All, KMemoryAttribute_AnyLocked | KMemoryAttribute_Locked));

        /* Validate that the dst address's state is valid. */
        KMemoryPermission dst_perm;
        R_TRY(this->CheckMemoryState(nullptr, std::addressof(dst_perm), nullptr, dst_address, size, KMemoryState_All, KMemoryState_Stack, KMemoryPermission_None, KMemoryPermission_None, KMemoryAttribute_All, KMemoryAttribute_None));

        /* Create an update allocator for the source. */
        KMemoryBlockManagerUpdateAllocator src_allocator(this->memory_block_slab_manager);
        R_TRY(src_allocator.GetResult());

        /* Create an update allocator for the destination. */
        KMemoryBlockManagerUpdateAllocator dst_allocator(this->memory_block_slab_manager);
        R_TRY(dst_allocator.GetResult());

        /* Unmap the memory. */
        {
            /* Determine the number of pages being operated on. */
            const size_t num_pages = size / PageSize;

            /* Create page groups for the memory being unmapped. */
            KPageGroup pg(this->block_info_manager);

            /* Create the page group representing the destination. */
            R_TRY(this->MakePageGroup(pg, dst_address, num_pages));

            /* Ensure the page group is the valid for the source. */
            R_UNLESS(this->IsValidPageGroup(pg, src_address, num_pages), svc::ResultInvalidMemoryRegion());

            /* We're going to perform an update, so create a helper. */
            KScopedPageTableUpdater updater(this);

            /* Unmap the aliased copy of the pages. */
            const KPageProperties dst_unmap_properties = { KMemoryPermission_None, false, false, false };
            R_TRY(this->Operate(updater.GetPageList(), dst_address, num_pages, Null<KPhysicalAddress>, false, dst_unmap_properties, OperationType_Unmap, false));

            /* Ensure that we re-map the aliased pages on failure. */
            auto remap_guard = SCOPE_GUARD {
                const KPageProperties dst_remap_properties = { dst_perm, false, false, false };
                MESOSPHERE_R_ABORT_UNLESS(this->MapPageGroupImpl(updater.GetPageList(), dst_address, pg, dst_remap_properties, true));
            };

            /* Try to set the permissions for the source pages back to what they should be. */
            const KPageProperties src_properties = { KMemoryPermission_UserReadWrite, false, false, false };
            R_TRY(this->Operate(updater.GetPageList(), src_address, num_pages, Null<KPhysicalAddress>, false, src_properties, OperationType_ChangePermissions, false));

            /* We successfully changed the permissions for the source pages, so we don't need to re-map the dst pages on failure. */
            remap_guard.Cancel();

            /* Apply the memory block updates. */
            this->memory_block_manager.Update(std::addressof(src_allocator), src_address, num_pages, src_state,         KMemoryPermission_UserReadWrite, KMemoryAttribute_None);
            this->memory_block_manager.Update(std::addressof(dst_allocator), dst_address, num_pages, KMemoryState_None, KMemoryPermission_None,          KMemoryAttribute_None);
        }

        return ResultSuccess();
    }

    KProcessAddress KPageTableBase::FindFreeArea(KProcessAddress region_start, size_t region_num_pages, size_t num_pages, size_t alignment, size_t offset, size_t guard_pages) const {
        KProcessAddress address = Null<KProcessAddress>;

        if (num_pages <= region_num_pages) {
            if (this->IsAslrEnabled()) {
                /* Try to directly find a free area up to 8 times. */
                for (size_t i = 0; i < 8; i++) {
                    const size_t random_offset = KSystemControl::GenerateRandomRange(0, (region_num_pages - num_pages - guard_pages) * PageSize / alignment) * alignment;
                    const KProcessAddress candidate = util::AlignDown(GetInteger(region_start + random_offset), alignment) + offset;

                    KMemoryInfo info;
                    ams::svc::PageInfo page_info;
                    MESOSPHERE_R_ABORT_UNLESS(this->QueryInfoImpl(&info, &page_info, candidate));

                    if (info.state != KMemoryState_Free) { continue; }
                    if (!(region_start <= candidate)) { continue; }
                    if (!(info.GetAddress() + guard_pages * PageSize <= GetInteger(candidate))) { continue; }
                    if (!(candidate + (num_pages + guard_pages) * PageSize - 1 <= info.GetLastAddress())) { continue; }
                    if (!(candidate + (num_pages + guard_pages) * PageSize - 1 <= region_start + region_num_pages * PageSize - 1)) { continue; }

                    address = candidate;
                    break;
                }
                /* Fall back to finding the first free area with a random offset. */
                if (address == Null<KProcessAddress>) {
                    /* NOTE: Nintendo does not account for guard pages here. */
                    /* This may theoretically cause an offset to be chosen that cannot be mapped. */
                    /* TODO: Should we account for guard pages? */
                    const size_t offset_pages = KSystemControl::GenerateRandomRange(0, region_num_pages - num_pages);
                    address = this->memory_block_manager.FindFreeArea(region_start + offset_pages * PageSize, region_num_pages - offset_pages, num_pages, alignment, offset, guard_pages);
                }
            }
            /* Find the first free area. */
            if (address == Null<KProcessAddress>) {
                address = this->memory_block_manager.FindFreeArea(region_start, region_num_pages, num_pages, alignment, offset, guard_pages);
            }
        }

        return address;
    }

    Result KPageTableBase::AllocateAndMapPagesImpl(PageLinkedList *page_list, KProcessAddress address, size_t num_pages, const KPageProperties properties) {
        MESOSPHERE_ASSERT(this->IsLockedByCurrentThread());

        /* Create a page group to hold the pages we allocate. */
        KPageGroup pg(this->block_info_manager);

        /* Allocate the pages. */
        R_TRY(Kernel::GetMemoryManager().Allocate(std::addressof(pg), num_pages, this->allocate_option));

        /* Ensure that the page group is open while we work with it. */
        KScopedPageGroup spg(pg);

        /* Clear all pages. */
        for (const auto &it : pg) {
            std::memset(GetVoidPointer(it.GetAddress()), this->heap_fill_value, it.GetSize());
        }

        /* Map the pages. */
        return this->Operate(page_list, address, num_pages, pg, properties, OperationType_MapGroup, false);
    }

    Result KPageTableBase::MapPageGroupImpl(PageLinkedList *page_list, KProcessAddress address, const KPageGroup &pg, const KPageProperties properties, bool reuse_ll) {
        MESOSPHERE_ASSERT(this->IsLockedByCurrentThread());

        /* Note the current address, so that we can iterate. */
        const KProcessAddress start_address = address;
        KProcessAddress cur_address = address;

        /* Ensure that we clean up on failure. */
        auto mapping_guard = SCOPE_GUARD {
            MESOSPHERE_ABORT_UNLESS(!reuse_ll);
            if (cur_address != start_address) {
                const KPageProperties unmap_properties = {};
                MESOSPHERE_R_ABORT_UNLESS(this->Operate(page_list, start_address, (cur_address - start_address) / PageSize, Null<KPhysicalAddress>, false, unmap_properties, OperationType_Unmap, true));
            }
        };

        /* Iterate, mapping all pages in the group. */
        for (const auto &block : pg) {
            /* We only allow mapping pages in the heap, and we require we're mapping non-empty blocks. */
            MESOSPHERE_ABORT_UNLESS(block.GetAddress() < block.GetLastAddress());
            MESOSPHERE_ABORT_UNLESS(IsHeapVirtualAddress(block.GetAddress(), block.GetSize()));

            /* Map and advance. */
            R_TRY(this->Operate(page_list, cur_address, block.GetNumPages(), GetHeapPhysicalAddress(block.GetAddress()), true, properties, OperationType_Map, reuse_ll));
            cur_address += block.GetSize();
        }

        /* We succeeded! */
        mapping_guard.Cancel();
        return ResultSuccess();
    }

    Result KPageTableBase::MakePageGroup(KPageGroup &pg, KProcessAddress addr, size_t num_pages) {
        MESOSPHERE_ASSERT(this->IsLockedByCurrentThread());

        const size_t size = num_pages * PageSize;

        /* We're making a new group, not adding to an existing one. */
        R_UNLESS(pg.empty(), svc::ResultInvalidCurrentMemory());

        auto &impl = this->GetImpl();

        /* Begin traversal. */
        TraversalContext context;
        TraversalEntry   next_entry;
        R_UNLESS(impl.BeginTraversal(std::addressof(next_entry), std::addressof(context), addr), svc::ResultInvalidCurrentMemory());

        /* Prepare tracking variables. */
        KPhysicalAddress cur_addr = next_entry.phys_addr;
        size_t cur_size = next_entry.block_size - (GetInteger(cur_addr) & (next_entry.block_size - 1));
        size_t tot_size = cur_size;

        /* Iterate, adding to group as we go. */
        while (tot_size < size) {
            R_UNLESS(impl.ContinueTraversal(std::addressof(next_entry), std::addressof(context)), svc::ResultInvalidCurrentMemory());

            if (next_entry.phys_addr != (cur_addr + cur_size)) {
                const size_t cur_pages = cur_size / PageSize;

                R_UNLESS(IsHeapPhysicalAddress(cur_addr), svc::ResultInvalidCurrentMemory());
                R_TRY(pg.AddBlock(GetHeapVirtualAddress(cur_addr), cur_pages));

                cur_addr           = next_entry.phys_addr;
                cur_size           = next_entry.block_size;
            } else {
                cur_size += next_entry.block_size;
            }

            tot_size += next_entry.block_size;
        }

        /* Ensure we add the right amount for the last block. */
        if (tot_size > size) {
            cur_size -= (tot_size - size);
        }

        /* add the last block. */
        const size_t cur_pages = cur_size / PageSize;
        R_UNLESS(IsHeapPhysicalAddress(cur_addr), svc::ResultInvalidCurrentMemory());
        R_TRY(pg.AddBlock(GetHeapVirtualAddress(cur_addr), cur_pages));

        return ResultSuccess();
    }

    bool KPageTableBase::IsValidPageGroup(const KPageGroup &pg, KProcessAddress addr, size_t num_pages) {
        MESOSPHERE_ASSERT(this->IsLockedByCurrentThread());

        const size_t size = num_pages * PageSize;

        /* Empty groups are necessarily invalid. */
        if (pg.empty()) {
            return false;
        }

        auto &impl = this->GetImpl();

        /* We're going to validate that the group we'd expect is the group we see. */
        auto cur_it = pg.begin();
        KVirtualAddress cur_block_address = cur_it->GetAddress();
        size_t cur_block_pages = cur_it->GetNumPages();

        auto UpdateCurrentIterator = [&]() ALWAYS_INLINE_LAMBDA {
            if (cur_block_pages == 0) {
                if ((++cur_it) == pg.end()) {
                    return false;
                }

                cur_block_address = cur_it->GetAddress();
                cur_block_pages   = cur_it->GetNumPages();
            }
            return true;
        };

        /* Begin traversal. */
        TraversalContext context;
        TraversalEntry   next_entry;
        if (!impl.BeginTraversal(std::addressof(next_entry), std::addressof(context), addr)) {
            return false;
        }

        /* Prepare tracking variables. */
        KPhysicalAddress cur_addr = next_entry.phys_addr;
        size_t cur_size = next_entry.block_size - (GetInteger(cur_addr) & (next_entry.block_size - 1));
        size_t tot_size = cur_size;

        /* Iterate, comparing expected to actual. */
        while (tot_size < size) {
            if (!impl.ContinueTraversal(std::addressof(next_entry), std::addressof(context))) {
                return false;
            }

            if (next_entry.phys_addr != (cur_addr + cur_size)) {
                const size_t cur_pages = cur_size / PageSize;

                if (!IsHeapPhysicalAddress(cur_addr)) {
                    return false;
                }

                if (!UpdateCurrentIterator()) {
                    return false;
                }

                if (cur_block_address != GetHeapVirtualAddress(cur_addr) || cur_block_pages < cur_pages) {
                    return false;
                }

                cur_block_address += cur_size;
                cur_block_pages   -= cur_pages;
                cur_addr           = next_entry.phys_addr;
                cur_size           = next_entry.block_size;
            } else {
                cur_size += next_entry.block_size;
            }

            tot_size += next_entry.block_size;
        }

        /* Ensure we compare the right amount for the last block. */
        if (tot_size > size) {
            cur_size -= (tot_size - size);
        }

        if (!IsHeapPhysicalAddress(cur_addr)) {
            return false;
        }

        if (!UpdateCurrentIterator()) {
            return false;
        }

        return cur_block_address == GetHeapVirtualAddress(cur_addr) && cur_block_pages == (cur_size / PageSize);
    }

    Result KPageTableBase::SetMemoryPermission(KProcessAddress addr, size_t size, ams::svc::MemoryPermission svc_perm) {
        MESOSPHERE_UNIMPLEMENTED();
    }

    Result KPageTableBase::SetProcessMemoryPermission(KProcessAddress addr, size_t size, ams::svc::MemoryPermission svc_perm) {
        const size_t num_pages = size / PageSize;

        /* Lock the table. */
        KScopedLightLock lk(this->general_lock);

        /* Verify we can change the memory permission. */
        KMemoryState old_state;
        KMemoryPermission old_perm;
        R_TRY(this->CheckMemoryState(std::addressof(old_state), std::addressof(old_perm), nullptr, addr, size, KMemoryState_FlagCode, KMemoryState_FlagCode, KMemoryPermission_None, KMemoryPermission_None, KMemoryAttribute_All, KMemoryAttribute_None));

        /* Make a new page group for the region. */
        KPageGroup pg(this->block_info_manager);

        /* Determine new perm/state. */
        const KMemoryPermission new_perm = ConvertToKMemoryPermission(svc_perm);
        KMemoryState new_state = old_state;
        const bool is_w = (new_perm & KMemoryPermission_UserWrite)   == KMemoryPermission_UserWrite;
        const bool is_x = (new_perm & KMemoryPermission_UserExecute) == KMemoryPermission_UserExecute;
        MESOSPHERE_ASSERT(!(is_w && is_x));

        if (is_w) {
            switch (old_state) {
                case KMemoryState_Code:      new_state = KMemoryState_CodeData;      break;
                case KMemoryState_AliasCode: new_state = KMemoryState_AliasCodeData; break;
                MESOSPHERE_UNREACHABLE_DEFAULT_CASE();
            }
        }

        /* Create a page group, if we're setting execute permissions. */
        if (is_x) {
            R_TRY(this->MakePageGroup(pg, GetInteger(addr), num_pages));
        }

        /* Create an update allocator. */
        KMemoryBlockManagerUpdateAllocator allocator(this->memory_block_slab_manager);
        R_TRY(allocator.GetResult());

        /* We're going to perform an update, so create a helper. */
        KScopedPageTableUpdater updater(this);

        /* Perform mapping operation. */
        const KPageProperties properties = { new_perm, false, false, false };
        const auto operation = is_x ? OperationType_ChangePermissionsAndRefresh : OperationType_ChangePermissions;
        R_TRY(this->Operate(updater.GetPageList(), addr, num_pages, Null<KPhysicalAddress>, false, properties, operation, false));

        /* Update the blocks. */
        this->memory_block_manager.Update(&allocator, addr, num_pages, new_state, new_perm, KMemoryAttribute_None);

        /* Ensure cache coherency, if we're setting pages as executable. */
        if (is_x) {
            for (const auto &block : pg) {
                cpu::StoreDataCache(GetVoidPointer(block.GetAddress()), block.GetSize());
            }
            cpu::InvalidateEntireInstructionCache();
        }

        return ResultSuccess();
    }

    Result KPageTableBase::SetHeapSize(KProcessAddress *out, size_t size) {
        MESOSPHERE_UNIMPLEMENTED();
    }

    Result KPageTableBase::SetMaxHeapSize(size_t size) {
        /* Lock the table. */
        KScopedLightLock lk(this->general_lock);

        /* Only process page tables are allowed to set heap size. */
        MESOSPHERE_ASSERT(!this->IsKernel());

        this->max_heap_size = size;

        return ResultSuccess();
    }

    Result KPageTableBase::QueryInfo(KMemoryInfo *out_info, ams::svc::PageInfo *out_page_info, KProcessAddress addr) const {
        /* If the address is invalid, create a fake block. */
        if (!this->Contains(addr, 1)) {
            *out_info = {
                .address          = GetInteger(this->address_space_end),
                .size             = 0 - GetInteger(this->address_space_end),
                .state            = static_cast<KMemoryState>(ams::svc::MemoryState_Inaccessible),
                .perm             = KMemoryPermission_None,
                .attribute        = KMemoryAttribute_None,
                .original_perm    = KMemoryPermission_None,
                .ipc_lock_count   = 0,
                .device_use_count = 0,
            };
            out_page_info->flags = 0;

            return ResultSuccess();
        }

        /* Otherwise, lock the table and query. */
        KScopedLightLock lk(this->general_lock);
        return this->QueryInfoImpl(out_info, out_page_info, addr);
    }

    Result KPageTableBase::MapIo(KPhysicalAddress phys_addr, size_t size, KMemoryPermission perm) {
        MESOSPHERE_ASSERT(util::IsAligned(GetInteger(phys_addr), PageSize));
        MESOSPHERE_ASSERT(util::IsAligned(size,                  PageSize));
        MESOSPHERE_ASSERT(size > 0);
        R_UNLESS(phys_addr < phys_addr + size, svc::ResultInvalidAddress());
        const size_t num_pages = size / PageSize;
        const KPhysicalAddress last = phys_addr + size - 1;

        /* Get region extents. */
        const KProcessAddress region_start     = this->GetRegionAddress(KMemoryState_Io);
        const size_t          region_size      = this->GetRegionSize(KMemoryState_Io);
        const size_t          region_num_pages = region_size / PageSize;

        /* Locate the memory region. */
        auto region_it    = KMemoryLayout::FindContainingRegion(phys_addr);
        const auto end_it = KMemoryLayout::GetEnd(phys_addr);
        R_UNLESS(region_it != end_it, svc::ResultInvalidAddress());

        MESOSPHERE_ASSERT(region_it->Contains(GetInteger(phys_addr)));

        /* Ensure that the region is mappable. */
        const bool is_rw = perm == KMemoryPermission_UserReadWrite;
        do {
            /* Check the region attributes. */
            R_UNLESS(!region_it->IsDerivedFrom(KMemoryRegionType_Dram),                      svc::ResultInvalidAddress());
            R_UNLESS(!region_it->HasTypeAttribute(KMemoryRegionAttr_UserReadOnly) || !is_rw, svc::ResultInvalidAddress());
            R_UNLESS(!region_it->HasTypeAttribute(KMemoryRegionAttr_NoUserMap),              svc::ResultInvalidAddress());

            /* Check if we're done. */
            if (GetInteger(last) <= region_it->GetLastAddress()) {
                break;
            }

            /* Advance. */
            region_it++;
        } while (region_it != end_it);

        /* Lock the table. */
        KScopedLightLock lk(this->general_lock);

        /* Select an address to map at. */
        KProcessAddress addr = Null<KProcessAddress>;
        const size_t phys_alignment = std::min(std::min(GetInteger(phys_addr) & -GetInteger(phys_addr), size & -size), MaxPhysicalMapAlignment);
        for (s32 block_type = KPageTable::GetMaxBlockType(); block_type >= 0; block_type--) {
            const size_t alignment = KPageTable::GetBlockSize(static_cast<KPageTable::BlockType>(block_type));
            if (alignment > phys_alignment) {
                continue;
            }

            addr = this->FindFreeArea(region_start, region_num_pages, num_pages, alignment, 0, this->GetNumGuardPages());
            if (addr != Null<KProcessAddress>) {
                break;
            }
        }
        R_UNLESS(addr != Null<KProcessAddress>, svc::ResultOutOfMemory());

        /* Check that we can map IO here. */
        MESOSPHERE_ASSERT(this->CanContain(addr, size, KMemoryState_Io));
        MESOSPHERE_R_ASSERT(this->CheckMemoryState(addr, size, KMemoryState_All, KMemoryState_Free, KMemoryPermission_None, KMemoryPermission_None, KMemoryAttribute_None, KMemoryAttribute_None));

        /* Create an update allocator. */
        KMemoryBlockManagerUpdateAllocator allocator(this->memory_block_slab_manager);
        R_TRY(allocator.GetResult());

        /* We're going to perform an update, so create a helper. */
        KScopedPageTableUpdater updater(this);

        /* Perform mapping operation. */
        const KPageProperties properties = { perm, true, false, false };
        R_TRY(this->Operate(updater.GetPageList(), addr, num_pages, phys_addr, true, properties, OperationType_Map, false));

        /* Update the blocks. */
        this->memory_block_manager.Update(&allocator, addr, num_pages, KMemoryState_Io, perm, KMemoryAttribute_None);

        /* We successfully mapped the pages. */
        return ResultSuccess();
    }

    Result KPageTableBase::MapStatic(KPhysicalAddress phys_addr, size_t size, KMemoryPermission perm) {
        MESOSPHERE_UNIMPLEMENTED();
    }

    Result KPageTableBase::MapRegion(KMemoryRegionType region_type, KMemoryPermission perm) {
        MESOSPHERE_UNIMPLEMENTED();
    }

    Result KPageTableBase::MapPages(KProcessAddress *out_addr, size_t num_pages, size_t alignment, KPhysicalAddress phys_addr, bool is_pa_valid, KProcessAddress region_start, size_t region_num_pages, KMemoryState state, KMemoryPermission perm) {
        MESOSPHERE_ASSERT(util::IsAligned(alignment, PageSize) && alignment >= PageSize);

        /* Ensure this is a valid map request. */
        R_UNLESS(this->CanContain(region_start, region_num_pages * PageSize, state), svc::ResultInvalidCurrentMemory());
        R_UNLESS(num_pages < region_num_pages,                                     svc::ResultOutOfMemory());

        /* Lock the table. */
        KScopedLightLock lk(this->general_lock);

        /* Find a random address to map at. */
        KProcessAddress addr = this->FindFreeArea(region_start, region_num_pages, num_pages, alignment, 0, this->GetNumGuardPages());
        R_UNLESS(addr != Null<KProcessAddress>, svc::ResultOutOfMemory());
        MESOSPHERE_ASSERT(util::IsAligned(GetInteger(addr), alignment));
        MESOSPHERE_ASSERT(this->CanContain(addr, num_pages * PageSize, state));
        MESOSPHERE_R_ASSERT(this->CheckMemoryState(addr, num_pages * PageSize, KMemoryState_All, KMemoryState_Free, KMemoryPermission_None, KMemoryPermission_None, KMemoryAttribute_None, KMemoryAttribute_None));

        /* Create an update allocator. */
        KMemoryBlockManagerUpdateAllocator allocator(this->memory_block_slab_manager);
        R_TRY(allocator.GetResult());

        /* We're going to perform an update, so create a helper. */
        KScopedPageTableUpdater updater(this);

        /* Perform mapping operation. */
        const KPageProperties properties = { perm, false, false, false };
        if (is_pa_valid) {
            R_TRY(this->Operate(updater.GetPageList(), addr, num_pages, phys_addr, true, properties, OperationType_Map, false));
        } else {
            R_TRY(this->AllocateAndMapPagesImpl(updater.GetPageList(), addr, num_pages, properties));
        }

        /* Update the blocks. */
        this->memory_block_manager.Update(&allocator, addr, num_pages, state, perm, KMemoryAttribute_None);

        /* We successfully mapped the pages. */
        *out_addr = addr;
        return ResultSuccess();
    }

    Result KPageTableBase::UnmapPages(KProcessAddress address, size_t num_pages, KMemoryState state) {
        MESOSPHERE_UNIMPLEMENTED();
    }

    Result KPageTableBase::MapPageGroup(KProcessAddress *out_addr, const KPageGroup &pg, KProcessAddress region_start, size_t region_num_pages, KMemoryState state, KMemoryPermission perm) {
        MESOSPHERE_ASSERT(!this->IsLockedByCurrentThread());

        /* Ensure this is a valid map request. */
        const size_t num_pages = pg.GetNumPages();
        R_UNLESS(this->CanContain(region_start, region_num_pages * PageSize, state), svc::ResultInvalidCurrentMemory());
        R_UNLESS(num_pages < region_num_pages,                                       svc::ResultOutOfMemory());

        /* Lock the table. */
        KScopedLightLock lk(this->general_lock);

        /* Find a random address to map at. */
        KProcessAddress addr = this->FindFreeArea(region_start, region_num_pages, num_pages, PageSize, 0, this->GetNumGuardPages());
        R_UNLESS(addr != Null<KProcessAddress>, svc::ResultOutOfMemory());
        MESOSPHERE_ASSERT(this->CanContain(addr, num_pages * PageSize, state));
        MESOSPHERE_R_ASSERT(this->CheckMemoryState(addr, num_pages * PageSize, KMemoryState_All, KMemoryState_Free, KMemoryPermission_None, KMemoryPermission_None, KMemoryAttribute_None, KMemoryAttribute_None));

        /* Create an update allocator. */
        KMemoryBlockManagerUpdateAllocator allocator(this->memory_block_slab_manager);
        R_TRY(allocator.GetResult());

        /* We're going to perform an update, so create a helper. */
        KScopedPageTableUpdater updater(this);

        /* Perform mapping operation. */
        const KPageProperties properties = { perm, state == KMemoryState_Io, false, false };
        R_TRY(this->MapPageGroupImpl(updater.GetPageList(), addr, pg, properties, false));

        /* Update the blocks. */
        this->memory_block_manager.Update(&allocator, addr, num_pages, state, perm, KMemoryAttribute_None);

        /* We successfully mapped the pages. */
        *out_addr = addr;
        return ResultSuccess();
    }

    Result KPageTableBase::MapPageGroup(KProcessAddress addr, const KPageGroup &pg, KMemoryState state, KMemoryPermission perm) {
        MESOSPHERE_ASSERT(!this->IsLockedByCurrentThread());

        /* Ensure this is a valid map request. */
        const size_t num_pages = pg.GetNumPages();
        const size_t size = num_pages * PageSize;
        R_UNLESS(this->CanContain(addr, size, state), svc::ResultInvalidCurrentMemory());

        /* Lock the table. */
        KScopedLightLock lk(this->general_lock);

        /* Check if state allows us to map. */
        R_TRY(this->CheckMemoryState(addr, size, KMemoryState_All, KMemoryState_Free, KMemoryPermission_None, KMemoryPermission_None, KMemoryAttribute_None, KMemoryAttribute_None));

        /* Create an update allocator. */
        KMemoryBlockManagerUpdateAllocator allocator(this->memory_block_slab_manager);
        R_TRY(allocator.GetResult());

        /* We're going to perform an update, so create a helper. */
        KScopedPageTableUpdater updater(this);

        /* Perform mapping operation. */
        const KPageProperties properties = { perm, state == KMemoryState_Io, false, false };
        R_TRY(this->MapPageGroupImpl(updater.GetPageList(), addr, pg, properties, false));

        /* Update the blocks. */
        this->memory_block_manager.Update(&allocator, addr, num_pages, state, perm, KMemoryAttribute_None);

        /* We successfully mapped the pages. */
        return ResultSuccess();
    }

    Result KPageTableBase::UnmapPageGroup(KProcessAddress address, const KPageGroup &pg, KMemoryState state) {
        MESOSPHERE_ASSERT(!this->IsLockedByCurrentThread());

        /* Ensure this is a valid unmap request. */
        const size_t num_pages = pg.GetNumPages();
        const size_t size = num_pages * PageSize;
        R_UNLESS(this->CanContain(address, size, state), svc::ResultInvalidCurrentMemory());

        /* Lock the table. */
        KScopedLightLock lk(this->general_lock);

        /* Check if state allows us to unmap. */
        R_TRY(this->CheckMemoryState(address, size, KMemoryState_All, state, KMemoryPermission_None, KMemoryPermission_None, KMemoryAttribute_All, KMemoryAttribute_None));

        /* Check that the page group is valid. */
        R_UNLESS(this->IsValidPageGroup(pg, address, num_pages), svc::ResultInvalidCurrentMemory());

        /* Create an update allocator. */
        KMemoryBlockManagerUpdateAllocator allocator(this->memory_block_slab_manager);
        R_TRY(allocator.GetResult());

        /* We're going to perform an update, so create a helper. */
        KScopedPageTableUpdater updater(this);

        /* Perform unmapping operation. */
        const KPageProperties properties = { KMemoryPermission_None, false, false, false };
        R_TRY(this->Operate(updater.GetPageList(), address, num_pages, Null<KPhysicalAddress>, false, properties, OperationType_Unmap, false));

        /* Update the blocks. */
        this->memory_block_manager.Update(&allocator, address, num_pages, KMemoryState_Free, KMemoryPermission_None, KMemoryAttribute_None);

        return ResultSuccess();
    }

    Result KPageTableBase::MakeAndOpenPageGroup(KPageGroup *out, KProcessAddress address, size_t num_pages, u32 state_mask, u32 state, u32 perm_mask, u32 perm, u32 attr_mask, u32 attr) {
        /* Ensure that the page group isn't null. */
        MESOSPHERE_ASSERT(out != nullptr);

        /* Make sure that the region we're mapping is valid for the table. */
        const size_t size = num_pages * PageSize;
        R_UNLESS(this->Contains(address, size), svc::ResultInvalidCurrentMemory());

        /* Lock the table. */
        KScopedLightLock lk(this->general_lock);

        /* Check if state allows us to create the group. */
        R_TRY(this->CheckMemoryState(address, size, state_mask | KMemoryState_FlagReferenceCounted, state | KMemoryState_FlagReferenceCounted, perm_mask, perm, attr_mask, attr));

        /* Create a new page group for the region. */
        R_TRY(this->MakePageGroup(*out, address, num_pages));

        /* Open a new reference to the pages in the group. */
        out->Open();

        return ResultSuccess();
    }

    Result KPageTableBase::UnlockForIpcUserBuffer(KProcessAddress address, size_t size) {
        return this->UnlockMemory(address, size,
                                  KMemoryState_FlagCanIpcUserBuffer, KMemoryState_FlagCanIpcUserBuffer,
                                  KMemoryPermission_None, KMemoryPermission_None,
                                  KMemoryAttribute_All, KMemoryAttribute_AnyLocked | KMemoryAttribute_Locked,
                                  KMemoryPermission_UserReadWrite,
                                  KMemoryAttribute_AnyLocked | KMemoryAttribute_Locked, nullptr);
    }

}