/*
 * 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>

namespace ams::kern::arch::arm64 {

    void KPageTableImpl::InitializeForKernel(void *tb, KVirtualAddress start, KVirtualAddress end) {
        this->table       = static_cast<L1PageTableEntry *>(tb);
        this->is_kernel   = true;
        this->num_entries = util::AlignUp(end - start, L1BlockSize) / L1BlockSize;
    }

    L1PageTableEntry *KPageTableImpl::Finalize() {
        return this->table;
    }

    bool KPageTableImpl::ExtractL3Entry(TraversalEntry *out_entry, TraversalContext *out_context, const L3PageTableEntry *l3_entry, KProcessAddress virt_addr) const {
        /* Set the L3 entry. */
        out_context->l3_entry = l3_entry;

        if (l3_entry->IsBlock()) {
            /* Set the output entry. */
            out_entry->phys_addr = l3_entry->GetBlock() + (virt_addr & (L3BlockSize - 1));
            if (l3_entry->IsContiguous()) {
                out_entry->block_size = L3ContiguousBlockSize;
            } else {
                out_entry->block_size = L3BlockSize;
            }

            return true;
        } else {
            out_entry->phys_addr  = Null<KPhysicalAddress>;
            out_entry->block_size = L3BlockSize;
            return false;
        }
    }

    bool KPageTableImpl::ExtractL2Entry(TraversalEntry *out_entry, TraversalContext *out_context, const L2PageTableEntry *l2_entry, KProcessAddress virt_addr) const {
        /* Set the L2 entry. */
        out_context->l2_entry = l2_entry;

        if (l2_entry->IsBlock()) {
            /* Set the output entry. */
            out_entry->phys_addr = l2_entry->GetBlock() + (virt_addr & (L2BlockSize - 1));
            if (l2_entry->IsContiguous()) {
                out_entry->block_size = L2ContiguousBlockSize;
            } else {
                out_entry->block_size = L2BlockSize;
            }
            /* Set the output context. */
            out_context->l3_entry = nullptr;
            return true;
        } else if (l2_entry->IsTable()) {
            return this->ExtractL3Entry(out_entry, out_context, this->GetL3EntryFromTable(GetPageTableVirtualAddress(l2_entry->GetTable()), virt_addr), virt_addr);
        } else {
            out_entry->phys_addr  = Null<KPhysicalAddress>;
            out_entry->block_size = L2BlockSize;
            out_context->l3_entry = nullptr;
            return false;
        }
    }

    bool KPageTableImpl::ExtractL1Entry(TraversalEntry *out_entry, TraversalContext *out_context, const L1PageTableEntry *l1_entry, KProcessAddress virt_addr) const {
        /* Set the L1 entry. */
        out_context->l1_entry = l1_entry;

        if (l1_entry->IsBlock()) {
            /* Set the output entry. */
            out_entry->phys_addr = l1_entry->GetBlock() + (virt_addr & (L1BlockSize - 1));
            if (l1_entry->IsContiguous()) {
                out_entry->block_size = L1ContiguousBlockSize;
            } else {
                out_entry->block_size = L1BlockSize;
            }
            /* Set the output context. */
            out_context->l2_entry = nullptr;
            out_context->l3_entry = nullptr;
            return true;
        } else if (l1_entry->IsTable()) {
            return this->ExtractL2Entry(out_entry, out_context, this->GetL2EntryFromTable(GetPageTableVirtualAddress(l1_entry->GetTable()), virt_addr), virt_addr);
        } else {
            out_entry->phys_addr  = Null<KPhysicalAddress>;
            out_entry->block_size = L1BlockSize;
            out_context->l2_entry = nullptr;
            out_context->l3_entry = nullptr;
            return false;
        }
    }

    bool KPageTableImpl::BeginTraversal(TraversalEntry *out_entry, TraversalContext *out_context, KProcessAddress address) const {
        /* Setup invalid defaults. */
        out_entry->phys_addr  = Null<KPhysicalAddress>;
        out_entry->block_size = L1BlockSize;
        out_context->l1_entry = this->table + this->num_entries;
        out_context->l2_entry = nullptr;
        out_context->l3_entry = nullptr;

        /* Validate that we can read the actual entry. */
        const size_t l0_index = GetL0Index(address);
        const size_t l1_index = GetL1Index(address);
        if (this->is_kernel) {
            /* Kernel entries must be accessed via TTBR1. */
            if ((l0_index != MaxPageTableEntries - 1) || (l1_index < MaxPageTableEntries - this->num_entries)) {
                return false;
            }
        } else {
            /* User entries must be accessed with TTBR0. */
            if ((l0_index != 0) || l1_index >= this->num_entries) {
                return false;
            }
        }

        /* Extract the entry. */
        const bool valid = this->ExtractL1Entry(out_entry, out_context, this->GetL1Entry(address), address);

        /* Update the context for next traversal. */
        switch (out_entry->block_size) {
            case L1ContiguousBlockSize:
                out_context->l1_entry += (L1ContiguousBlockSize / L1BlockSize) - GetContiguousL1Offset(address) / L1BlockSize;
                break;
            case L1BlockSize:
                out_context->l1_entry += 1;
                break;
            case L2ContiguousBlockSize:
                out_context->l1_entry += 1;
                out_context->l2_entry += (L2ContiguousBlockSize / L2BlockSize) - GetContiguousL2Offset(address) / L2BlockSize;
                break;
            case L2BlockSize:
                out_context->l1_entry += 1;
                out_context->l2_entry += 1;
                break;
            case L3ContiguousBlockSize:
                out_context->l1_entry += 1;
                out_context->l2_entry += 1;
                out_context->l3_entry += (L3ContiguousBlockSize / L3BlockSize) - GetContiguousL3Offset(address) / L3BlockSize;
                break;
            case L3BlockSize:
                out_context->l1_entry += 1;
                out_context->l2_entry += 1;
                out_context->l3_entry += 1;
                break;
            MESOSPHERE_UNREACHABLE_DEFAULT_CASE();
        }

        return valid;
    }

    bool KPageTableImpl::ContinueTraversal(TraversalEntry *out_entry, TraversalContext *context) const {
        bool valid = false;

        /* Check if we're not at the end of an L3 table. */
        if (!util::IsAligned(reinterpret_cast<uintptr_t>(context->l3_entry), PageSize)) {
            valid = this->ExtractL3Entry(out_entry, context, context->l3_entry, Null<KProcessAddress>);

            switch (out_entry->block_size) {
                case L3ContiguousBlockSize:
                    context->l3_entry += (L3ContiguousBlockSize / L3BlockSize);
                    break;
                case L3BlockSize:
                    context->l3_entry += 1;
                    break;
                MESOSPHERE_UNREACHABLE_DEFAULT_CASE();
            }
        } else if (!util::IsAligned(reinterpret_cast<uintptr_t>(context->l2_entry), PageSize)) {
            /* We're not at the end of an L2 table. */
            valid = this->ExtractL2Entry(out_entry, context, context->l2_entry, Null<KProcessAddress>);

            switch (out_entry->block_size) {
                case L2ContiguousBlockSize:
                    context->l2_entry += (L2ContiguousBlockSize / L2BlockSize);
                    break;
                case L2BlockSize:
                    context->l2_entry += 1;
                    break;
                case L3ContiguousBlockSize:
                    context->l2_entry += 1;
                    context->l3_entry += (L3ContiguousBlockSize / L3BlockSize);
                    break;
                case L3BlockSize:
                    context->l2_entry += 1;
                    context->l3_entry += 1;
                    break;
                MESOSPHERE_UNREACHABLE_DEFAULT_CASE();
            }
        } else {
            /* We need to update the l1 entry. */
            const size_t l1_index = context->l1_entry - this->table;
            if (l1_index < this->num_entries) {
                valid = this->ExtractL1Entry(out_entry, context, context->l1_entry, Null<KProcessAddress>);
            } else {
                /* Invalid, end traversal. */
                out_entry->phys_addr  = Null<KPhysicalAddress>;
                out_entry->block_size = L1BlockSize;
                context->l1_entry = this->table + this->num_entries;
                context->l2_entry = nullptr;
                context->l3_entry = nullptr;
                return false;
            }

            switch (out_entry->block_size) {
                case L1ContiguousBlockSize:
                    context->l1_entry += (L1ContiguousBlockSize / L1BlockSize);
                    break;
                case L1BlockSize:
                    context->l1_entry += 1;
                    break;
                case L2ContiguousBlockSize:
                    context->l1_entry += 1;
                    context->l2_entry += (L2ContiguousBlockSize / L2BlockSize);
                    break;
                case L2BlockSize:
                    context->l1_entry += 1;
                    context->l2_entry += 1;
                    break;
                case L3ContiguousBlockSize:
                    context->l1_entry += 1;
                    context->l2_entry += 1;
                    context->l3_entry += (L3ContiguousBlockSize / L3BlockSize);
                    break;
                case L3BlockSize:
                    context->l1_entry += 1;
                    context->l2_entry += 1;
                    context->l3_entry += 1;
                    break;
                MESOSPHERE_UNREACHABLE_DEFAULT_CASE();
            }
        }

        return valid;
    }

    bool KPageTableImpl::GetPhysicalAddress(KPhysicalAddress *out, KProcessAddress address) const {
        /* Validate that we can read the actual entry. */
        const size_t l0_index = GetL0Index(address);
        const size_t l1_index = GetL1Index(address);
        if (this->is_kernel) {
            /* Kernel entries must be accessed via TTBR1. */
            if ((l0_index != MaxPageTableEntries - 1) || (l1_index < MaxPageTableEntries - this->num_entries)) {
                return false;
            }
        } else {
            /* User entries must be accessed with TTBR0. */
            if ((l0_index != 0) || l1_index >= this->num_entries) {
                return false;
            }
        }

        /* Try to get from l1 table. */
        const L1PageTableEntry *l1_entry = this->GetL1Entry(address);
        if (l1_entry->IsBlock()) {
            *out = l1_entry->GetBlock() + GetL1Offset(address);
            return true;
        } else if (!l1_entry->IsTable()) {
            return false;
        }

        /* Try to get from l2 table. */
        const L2PageTableEntry *l2_entry = this->GetL2Entry(l1_entry, address);
        if (l2_entry->IsBlock()) {
            *out = l2_entry->GetBlock() + GetL2Offset(address);
            return true;
        } else if (!l2_entry->IsTable()) {
            return false;
        }

        /* Try to get from l3 table. */
        const L3PageTableEntry *l3_entry = this->GetL3Entry(l2_entry, address);
        if (l3_entry->IsBlock()) {
            *out = l3_entry->GetBlock() + GetL3Offset(address);
            return true;
        }

        return false;
    }

}